ITEM 1. BUSINESS

Overview

We are a biopharmaceutical company focused on the development and commercialization of novel therapeutics in the areas of thrombosis, other hematologic disorders and inflammation for patients who currently have limited or no approved treatment options. We are advancing our three wholly-owned compounds using novel biomarker and genetic approaches that may increase the likelihood of clinical, regulatory and commercial success of our potentially life-saving therapies. Two of these compounds were discovered through our internal research efforts and one was discovered by Portola scientists during their time at a prior company.

Our Phase 3 programs address significant unmet medical needs in the area of thrombosis, or blood clots. Betrixaban, a U.S. Food and Drug Administration, or FDA,-designated Fast-Track novel oral once-daily inhibitor of Factor Xa, or fXa, is in a Phase 3 clinical trial for extended duration prophylaxis, or preventive treatment, of a form of thrombosis known as venous thromboembolism, or VTE, in acute medically ill patients for 35 days of in-hospital and post-discharge use. We completed enrollment of 7,514 patients in the fourth quarter of 2015 and expect to report top line data from our APEX study in early April 2016. Currently, there is no anticoagulant approved for extended duration VTE prophylaxis in the acute medically ill population. Our second Phase 3 compound Andexanet alfa, an FDA-designated  breakthrough therapy and orphan drug, is a recombinant protein designed to reverse anticoagulant activity in patients treated with a fXa inhibitor. Andexanet alfa has potential indications for patients anticoagulated with a direct or indirect fXa inhibitor when reversal of anticoagulation is needed, such as in life-threatening or uncontrolled bleeding or for emergency surgery or urgent procedures. We filed a Biologics License Application, or BLA, to the FDA in the first quarter of 2016. We have completed Phase 3 registration studies in healthy volunteers and are currently evaluating Andexanet alfa in Phase 2 clinical trials. We are also conducting a Phase 4 confirmatory trial in patients. Our third product candidate, Cerdulatinib, is an orally available dual kinase inhibitor that inhibits spleen tyrosine kinase, or Syk, and Janus kinases, or JAK, enzymes that regulate important signaling pathways.  Cerdulatinib is being developed for hematologic, or blood, cancers and inflammatory disorders. We are currently conducting a Phase 1/2a proof-of-concept study for Cerdulatinib in patients with non-Hodgkin’s lymphoma, or NHL, or chronic lymphocytic leukemia, or CLL, who have failed or relapsed on existing marketed therapies or products in development, including patients with identified mutations. In the Phase 1 dose escalation portion of the study, we have yet to reach the maximum tolerated dose and enrollment continues. Based on interim Phase 1 data, we plan to advance Cerdulatinib to the Phase 2a portion of the study, which includes expansion cohorts in select hematologic cancers. We also have a program of highly selective Syk inhibitors, one of which is partnered with Ora Inc., or Ora.

We have full worldwide commercial rights to Betrixaban and Cerdulatinib and to Andexanet alfa outside of Japan. In January 2016, we licensed commercial rights to Andexanet alfa in Japan to Bristol-Myers Squibb Company, or BMS, and Pfizer Inc., or Pfizer. We believe we can maximize the value of our company by retaining substantial commercialization rights to these three product candidates and, where appropriate, entering into additional partnerships to develop and commercialize these product candidates. We plan on building a successful enterprise to commercialize Betrixaban and Andexanet alfa, using a hospital-based sales team in the United States and possibly other major markets and with additional partners in other territories.

Betrixaban

Betrixaban is a novel oral once-daily inhibitor of fXa in development for extended duration VTE prophylaxis in acute medically ill patients for 35 days of in-hospital and post-discharge use. Acute medically ill patients are those who are hospitalized for serious non-surgical conditions, such as heart failure, stroke, infection, rheumatic disorders and pulmonary disorders. We estimate that in the G7 countries in 2014 there were 22.5 million acute medically ill patients for whom VTE prophylaxis was recommended by medical treatment guidelines. The current standard of care for VTE prophylaxis in this population is enoxaparin, an injectable low molecular weight heparin that is approved for deep vein thrombosis, or DVT, prophylaxis in medical patients who are at risk for thromboembolic complications due to severely restricted mobility during acute illness. The usual duration of administration of enoxaparin is 6 to 11 days. According to IMS Health Incorporated, or IMS, a healthcare industry information provider, worldwide sales of enoxaparin for 2015 were $2.9 billion. The use of enoxaparin in acute medically ill patients accounted for approximately $1.4 billion of these sales.

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Multiple large, global trials have demonstrated that there is substantial risk of VTE in acute medically ill patients with restricted mobility and other risk factors beyond the standard course of enoxaparin. Our Phase 3 APEX study wa s designed to use biomarkers to identify and enroll patients most likely to benefit from therapy with Betrixaban. Specifically, these patients have elevated blood levels of D-dimer or are over age 75. There have been numerous publications highlighting the role of these two prognostic markers in identifying patients at extended risk of VTE. The MAGELLAN trial sponsored by Bayer Pharma AG , or Bayer, and Janssen Pharmaceutica ls, Inc., or Janssen, which evaluated administration of rivaroxaban for an extended period , demonstrated that the incidence of VTE-related death rose four-fold over several weeks after hospital discharge and the discontinuation of treatment. However, there are no therapies approved for use beyond 14 days despite the ongoing risk of VTE faced by these patients for 35 days or more following hospital admission. We are developing Betrixa ban to be the first oral f Xa inhibitor approved for use in acute medically ill patients and the first anticoagulant approved for extended period hospital-to-home VTE prophylaxis in these patients. We believe the addressable market opportunity for Betrixaban c ould range from $3.0 billion to $4.0 billion , annually, by 2020 .

In 2012, we initiated our pivotal biomarker-based Phase 3 APEX study, a randomized, double-blind, double dummy, active-controlled, multicenter, multinational study to evaluate a once-daily dose of Betrixaban for 35 days for superiority as compared to in-hospital administration of enoxaparin once daily for 6 to 14 days followed by placebo for the remainder of the study period. Our APEX study was conducted in 35 countries worldwide. In the third quarter of 2015, we completed a planned protocol-defined sample size re-assessment and increased the size of the trial from 6,850 to approximately 7,500 patients. The increase in sample size was designed to ensure APEX statistical power for the primary efficacy analysis patient cohort and increases power in the overall patient population analysis. We have submitted our statistical analysis plan to the FDA. We completed APEX patient enrollment in the fourth quarter of 2015 and expect to report top line data from the study in early April 2016, and assuming positive trial results, we expect to submit a new drug application, or NDA, to the FDA in the third quarter of 2016. In the fourth quarter of 2015, Betrixaban received Fast-Track designation from the FDA for prevention of blood clots in acute medically ill patients. Fast-Track designation is generally intended by the FDA to facilitate the development, and expedite the review, of drugs which treat a serious or life-threatening condition and fill an unmet medical need.

We believe Betrixaban has the potential to succeed in the targeted patient population, in part due to its validated mechanism of action, but also most importantly, due to its properties that differentiate it from other anticoagulants.  First, it has the longest half-life of all the fXa inhibitors, making it a true, once-daily therapy allowing for a narrow peak-to-trough concentration ratio that helps maintain a less variable anticoagulant effect over the course of a day.  Second, it has the lowest renal clearance of all of the fXa inhibitors, which may result in a lower rate of bleeding. Finally, it is not metabolized in the liver by an enzyme called CYP 3A4, which may result in reduced potential for drug-on-drug interactions. These properties are critically important for acute medically ill patients who are often renally compromised and on multiple concomitant medications. 

In early 2013, we entered into a clinical collaboration agreement with Lee’s Pharmaceutical (HK) Ltd, or Lee’s, to jointly expand our Phase 3 APEX study of Betrixaban into China with an exclusive option for Lee’s to negotiate for the exclusive commercial rights to Betrixaban in China. We completed APEX enrollment before the parties were able to find a regulatory pathway to expand the study into China.

Andexanet alfa

Andexanet alfa, an FDA-designated breakthrough therapy and orphan drug, is a recombinant protein designed to reverse anticoagulant activity in patients treated with a fXa inhibitor. Andexanet alfa has potential indications for patients anticoagulated with a direct or indirect fXa inhibitor when reversal of anticoagulation is needed, such as in life-threatening or uncontrolled bleeding or for emergency surgery or urgent procedures. Currently, there is no antidote or reversal agent approved for use against fXa inhibitors. Leading clinicians have identified, and the FDA has recognized, the lack of an effective reversal agent for fXa inhibitors as a significant unmet clinical need. Based on industry data, we estimate that in 2020, between 23 million and 36 million patients will be treated with fXa inhibitors, including low molecular weight heparins, for short-term use or chronic conditions. Clinical trial results suggest that, depending on their underlying medical condition, annually between 1% and 4% of these patients may experience a major bleeding event and an additional 1% may require emergency surgery. We believe that Andexanet alfa, if approved, has the long-term potential to address a total worldwide market in excess of $2.0 billion.

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Andexanet alfa is the first therapy to de monstrate reversal of the a nticoagulant activity of f Xa inhibitors as measured by anti-fX a levels. We have complet ed two Phase 3 ANNEXA ^TM (Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of fXa Inhibitors) studies – one with Bristol-Myers Squibb Company, or BMS , and Pfizer Inc.’s, or Pfizer’s, f Xa inhibitor, apixaban and one with Bayer Pharma AG, or Bayer, and Janssen Pharmaceuticals, Inc., or Janssen ’s , f Xa inhibitor, rivaroxaban . Our Phase 3 studies each consist ed of two par ts. In the first part of each study, the effect of a single bolus of Andexanet alfa was evaluated in healthy volunteers who had been given apixaban or rivaroxaban . In the second part of each study, the ability of Andexanet alfa to sustain reversal of the a nticoagulant effects of apixaban and rivaroxaban was evaluated by administering a bolus plus infusion of Andexanet alfa to healthy volunteers who ha d been given apixaban or rivaroxaban . The first part of our Phase 3 ANNEXA studies of a single bolus of Ande xanet alfa with apixaban and with rivaroxaban met their primary and secondary endpoints with high statistical significance (p-values of less than 0.0001).The second part of our Phase 3 ANNEXA studies of a bolus plus infusion of Andexanet alfa with apixaban and with rivaroxaban both also met their primary and secondary endpoints with high statistical significance (p-value of less than 0.0001). In November 2015, the data from the Phase 3 studies was published in the New England Journal of Medicine. In early 2 015, we initiated a Phase 4 ANNEXA confirmatory patient study, as agreed to by the FDA and European Medicines Agency, or EMA . This study is part of an accelerated approval pathway in the United States for Andexanet alfa. This open-label, single-arm study is being conducted in patients receiving apixaban, rivaroxaban , edoxaban or enoxaparin (a low molecular weight heparin) who present with certain acute major bleed s . Pursuant to active and ongoing discussions with the FDA, we include d data from a small numb er of patients from this study in our Biologics License Application, or BLA, which we filed in early 201 6 for conditional approval.

We have also completed a series of Phase 2 proof-of-concept studies evaluating the safety and activity of Andexanet alfa in healthy volunteers who were administered one of several fXa inhibitors. Analysis of anticoagulation markers in blood samples taken from the subjects in these studies demonstrated that Andexanet alfa produced immediate reversal of anticoagulant activity of the fXa inhibitors apixaban, rivaroxaban, edoxaban and enoxaparin and that the reversal could be sustained. Additionally, we are conducting a Phase 2 proof-of-concept study evaluating the reversal of Betrixaban.

We have entered into collaboration agreements with BMS and Pfizer, Bayer and Janssen, and Daiichi Sankyo, Inc., or Daiichi Sankyo, to support Phase 2 and Phase 3 clinical studies with apixaban, rivaroxaban and edoxaban, respectively. We have also entered into licensing and collaboration agreements with BMS, Pfizer and Bayer to obtain the right to pursue final regulatory approval and commercialize Andexanet alfa as a reversal agent in Japan. We retain commercial rights with respect to Andexanet alfa outside of Japan.

Cerdulatinib

In addition to our thrombosis compounds, we are developing orally available kinase inhibitors to treat hematologic disorders and inflammation.  Cerdulatinib is an orally available, potent inhibitor of Syk and JAK, enzymes that regulate two important signaling pathways.  Scientists have demonstrated that both Syk and JAK play key roles in various hematologic cancers and inflammatory diseases. We are developing Cerdulatinib for treatment of certain B-cell hematologic cancers. We are conducting a Phase 1/2a proof-of-concept study of Cerdulatinib in NHL, and CLL, patients. In the Phase 1 dose escalation portion of the study, we have yet to reach the maximum tolerated dose and enrollment continues. We are exploring alternate dosing regimens and formulations to get a higher exposure of Cerdulatinib in patients.  Based on interim Phase 1 data we plan to advance Cerdulatinib into the Phase 2a portion of the study in 2016 which includes expansion cohorts in select hematologic cancers.

Syk-selective inhibitors

Syk is an important mediator of immune response in a number of different types of immune cells. We have a program of highly selective Syk inhibitors, one of which is partnered with Ora. Ora is leading the pre-clinical study of a selective Syk inhibitor for allergic conjunctivitis.

In May 2015, our Biogen Idec agreement was terminated in its entirety, and we entered into a license and collaboration agreement with Ora pursuant to which we granted Ora an exclusive license to co-develop and co-commercialize one of our specific Syk inhibitors, PRT02761. Ora has the primary responsibility for conducting the research and development and regulatory activities under this agreement. We are obligated to provide assistance in accordance with the agreed-upon development plan, as well as participate on various committees.

Under the terms of this risk and cost sharing agreement, each party will incur its own share of development costs. Third-party related development costs will be shared by Ora and us at approximately 60% and 40%, respectively, until an End of Phase 2 meeting with the FDA, and equally thereafter. We are entitled to receive either 50% of the profits, if any, generated by future sales of the products developed under the agreement or royalty payments on such sales, should we opt out of the agreement.

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We may opt out of the agreement any time prior to 90 days after an End of Phase 2 meeting with the FDA. The timing of the exercise of our opt out rights would impact any future royalties we would be entitled to receive from Ora. Each party may also buy out the rights and interests in the licensed compound by payi ng the greater of $6.0 million or two times the actual aggregate development cost incurred by both parties on or before the date that is 90 days after an End of Phase 2 meeting with the FDA .

Our strategy

Our goal is to build an enduring biopharmaceutical company with a foundation of products and product candidates that significantly advance patient care in the areas of thrombosis, other hematologic disorders and inflammation. We have a clear strategy focused on biomarker or genetic approaches to clinical development that we believe will increase the probability of clinical, regulatory and commercial success of our first-in-class therapies. Key elements of our strategy are as follows:

Complete the clinical development of Betrixaban . We completed enrollment in our global pivotal Phase 3 clinical study, APEX, in the fourth quarter of 2015 and plan to release top line data from this study in early April 2016. APEX, is evaluating the efficacy and safety of our lead product candidate Betrixaban for extended duration VTE prophylaxis during a hospital stay as well as post-discharge for 35 days in acute medically ill patients with restricted mobility and other risk factors. If APEX is successful and we receive regulatory approval, Betrixaban will be the first anticoagulant approved based on a biomarker approach for the multi-billion dollar market for extended VTE prophylaxis in acute medically ill patients, both in the hospital and after discharge.

Advance Andexanet alfa through an expedited development and approval process . We are pursuing an Accelerated Approval pathway for our FDA-designated breakthrough therapy and orphan drug, Andexanet alfa. Based on clinical trial results and discussions with the FDA, we believe that the FDA supports our pursuit of this approval pathway. Based on our Phase 3 ANNEXA clinical studies in healthy volunteers, we filed a BLA for conditional approval in the first quarter of 2016, which included a small amount of patient data from our Phase 4 ANNEXA-4 confirmatory study, which was initiated in early 2015. Additionally, we are in the process of scheduling meetings with our appointed rapporteurs representing the EMA regarding our plan to submit a Marketing Authorization Application, or MAA, through a centralized procedure for conditional approval in Europe.

Commercialize Betrixaban and Andexanet alfa, if approved, in the United States using a hospital-focused sales force . We plan to commercialize both of our thrombosis product candidates with a U.S. hospital-based sales force of approximately 100 to 150 sales representatives. We believe we will be able to address the multi-billion dollar markets for our thrombosis products with a targeted sales and marketing effort because hospitals represent a concentrated customer base as compared to primary care or specialty physicians. We have licensed commercial rights to Andexanet alfa in Japan to BMS and Pfizer. Outside the United States, we are evaluating our commercial strategy.

Advance Cerdulatinib for treatment of hematologic cancers . We are currently evaluating Cerdulatinib in a Phase 1/2a proof-of-concept study in NHL and CLL. In the Phase 1 dose escalation portion of the study, we have yet to reach the maximum tolerated dose and enrollment continues. Based on interim Phase 1 data, we plan to advance Cerdulatinib into the Phase 2a portion of the study in 2016 which includes expansion cohorts in select hematologic cancers. Cerdulatinib targets two key signaling pathways that can promote cancer cell growth. This product candidate has the potential for broad activity in hematologic cancers because it blocks the B-cell receptor pathway via Syk and key cytokine receptors via JAK. Our strategy for Cerdulatinib is to focus on patients that have shown limited response to other therapies or have relapsed or do not respond due to mutations.

Deploy capital strategically to develop our portfolio of product candidates and create value . We expect to continue to deploy most of our capital resources to develop and commercialize Betrixaban and Andexanet alfa and to a lesser extent, advance Cerdulatinib into clinical expansion cohorts. It is our strategy to leverage established clinical trial design principles as well as proactive engagement with relevant regulatory authorities to advance these candidates towards key value inflection points in a capital-efficient manner. In parallel with these efforts, we have entered into and anticipate that we will continue to seek and evaluate partnerships that provide support for the further development of our product candidates while retaining significant economic and commercial rights. We believe that this combination of independent development and partnering activity may allow us to realize the substantial potential value of our product candidates while reducing our capital requirements.

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Product candidates

Our development pipeline, summarized in the table below, includes three wholly owned compounds and one partnered program.

Betrixaban

We are developing Betrixaban to be the first anticoagulant approved for extended duration VTE prophylaxis in acute medically ill patients both in-hospital and after discharge for 35 days. Acute medically ill patients are patients hospitalized for non-surgical conditions, such as heart failure, stroke, infection, rheumatic disorders and pulmonary disorders. Acute medically ill patients with restricted mobility and other risk factors are known to be at increased risk for VTE, both in the hospital and after discharge. Each year, more than 150,000 acute medically ill patients worldwide die of VTE and not from their underlying medical condition. Pulmonary embolism is the most common preventable cause of hospital death and a leading cause of increased length of hospital stay. The average annual direct medical cost of treating VTE in a hospital setting in the United States is between $7,500 and $16,500 per patient and is even greater for elderly, higher risk patients. Both the National Quality Forum and the Joint Commission on Accreditation of Healthcare Organizations include the utilization of VTE prevention measures as a leading indicator of quality of patient care.

While there are a number of anticoagulants approved for short-duration VTE prophylaxis in acute medically ill patients during the typical hospitalization period, there is no anticoagulant approved for extended duration VTE prophylaxis in this population. Acute medically ill patients at risk for VTE are typically treated with intravenous or injectable heparin or an injectable low molecular weight heparin, such as enoxaparin, marketed as Lovenox® and also available in generic form, while in the hospital but are often either not used, or are used only for a short period following discharge. Multiple large regional and global studies have demonstrated that there is a substantial risk of VTE after hospital discharge in acute medically ill patients with restricted mobility and other risk factors. For example, the MAGELLAN trial of 8,101 patients showed that the rate of VTE-related death for the 10-day period while the patients were in the hospital receiving anticoagulation therapy was 0.2%, while the rate of VTE-related death for the 25-day post-discharge period when the patient did not receive anticoagulation treatment, was 0.8%, a four-fold increase. One academic study examined the medical records of approximately 11,000 acute medically ill patients for a period of 180 days after hospital admission and determined that 56.6% of VTE events in this population occurred after discharge. These studies highlight the need for more effective extended duration prophylaxis therapies.

We are developing Betrixaban to be the first oral fXa inhibitor approved for use in acute medically ill patients and the first anticoagulant approved for extended duration VTE prophylaxis in those patients. We are evaluating Betrixaban in APEX, a global Phase 3 clinical study using a biomarker approach by focusing on patients that are most likely to benefit, specifically those with elevated D-dimer blood levels or those over the age of 75. In the field of thrombosis, it is well established that the outcomes of Phase 3 trials are significantly influenced by three factors: drug properties, dose selection and selection of the patients who will benefit most from treatment. Applying our knowledge of Betrixaban’s properties, our clinical experience with Betrixaban and learnings from fXa inhibitor clinical trials conducted by other companies, we believe we have designed the APEX study to enhance the likelihood of its success, despite the lack of success of other fXa inhibitors in this indication, based on the following factors:

Drug properties . Betrixaban’s unique pharmacodynamic and pharmacokinetic properties compared to other oral fXa inhibitors include a long half-life suitable for once-daily dosing, low renal clearance, which reduces the risk of drug accumulation, and low drug-drug interaction potential due to lack of metabolism by the CYP3A4 pathway, a key metabolic route for many other drugs.

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Dosing . The dosing regimen in our APEX study is designed to provide immediate anticoagulation for patients in the hospital and to maintain a therapeutic level of anticoagulation over 24 hours with each oral once-daily dose for 35 days to reduce variab ility and potential for increased bleeding risk from supratherapeutic drug levels or increased VTE risk from subtherapeutic drug levels. We chose the dosing regimen of Betrixaban administered in APEX based on extensive modeling from our preclinical and cli nical experience with Betrixaban and analysis of efficacy, safety and pharmacokinetic data from clinical trials of ot her f Xa inhibitors.

Patient population . The APEX patient population, which is based on extensive review of epidemiologic studies and data from multiple large trials in acute medically ill patients, targets the specific patients with certain risk factors who are at an increased risk for VTE and can potentially benefit from extended duration VTE prophylaxis both during a hospital stay and post-discharge for 35 days, while excluding those at increased risk of bleeding, the main side effect of all anticoagulants.

Overview of thrombosis

Thrombosis is the leading cause of mortality and morbidity in the western world. Thrombosis arises from an abnormal or excessive activation of the body’s natural clotting process, resulting in the formation of a clot inside a blood vessel that disrupts normal blood flow. If the clot detaches from the blood vessel wall and travels through the body, known as thromboembolism, it can damage vital organs, such as the brain, heart and lungs. Clots that block arteries can lead to myocardial infarctions, more commonly referred to as heart attacks, or a form of stroke known as ischemic strokes. Our Betrixaban development efforts are currently focused on VTE, with the two most common conditions being deep vein thrombosis, or DVT, which typically leads to pain and swelling in the leg, and pulmonary embolism, which occurs when a clot disrupts blood flow to the lungs, leading to lung damage or even death. In the United States, on an annual basis, 1.2 million people have a new or recurrent heart attack, 700,000 people suffer an ischemic stroke and 350,000 to 600,000 people have a VTE.

Thrombosis is generally prevented or treated using either anticoagulants, commonly known as blood thinners, or another class of drugs known as antiplatelet agents. The specific drug, dose and dosing frequency and duration of treatment depends on a patient’s underlying disease and treatment setting, such as during surgery, in the hospital or at home. In some cases, these agents may be used in sequence or combination.

Prophylaxis against all forms of thrombosis is a major medical need throughout the developed world. For example, in the G7 countries, the United States, Japan, France, Germany, Italy, Spain and the United Kingdom, existing medical guidelines recommend that a population of approximately 46.4 million patients receive some form of anticoagulation drug therapy to reduce their risk of thrombosis. The largest category of patients at risk for thrombosis is the acute medically ill, whose risk is increased for those patients immobilized for more than a few days or with other risk factors. In addition to acute medically ill patients, populations at risk for thrombosis include patients with atrial fibrillation, acute coronary syndrome, recent VTE and certain genetic mutations, as well as surgical patients undergoing orthopedic or abdominal procedures.

The table below shows our estimate of the number of patients in the G7 countries, categorized by medical condition or procedure, for whom a Class I medical guideline recommendation of anticoagulation drug therapy would apply. A Class I medical guideline recommendation represents the highest level of recommendation that patients receive specified medical treatment based on the evidence of the relative risks and benefits of such treatment.

Patients with Class I medical guideline recommendation to receive anticoagulation drug therapy

The population of acute medically ill patients represents the largest patient segment in the anticoagulant market, accounting for nearly half of patients in the G7 countries. Despite the short duration of current VTE prophylaxis for the acute medically ill, typically 6 to 11 days, we believe that at its peak, annual worldwide sales of enoxaparin for use in acute medically ill patients were at least $1.4 billion.

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VTE in acute medically ill patients

The standard of care for VTE prophylaxis in acute medically ill patients is to treat those patients who have certain risk factors with an anticoagulant, such as heparin or enoxaparin, for 6 to 14 days, primarily while the patient is in the hospital. Factors that have been identified as increasing the risk of VTE include several days of restricted mobility, age, an elevated blood marker known as D-dimer, previous VTE event, family history of VTE, smoking, hormonal therapy and others. Almost all hospitalized non-surgical patients have at least one of these risk factors, and approximately two-thirds have two or more risk factors. In-hospital use of anticoagulation has been shown to reduce the incidence of VTEs by approximately 63% and have a net clinical benefit; however, recent registry studies and clinical trials have shown that acute medically ill patients remain at a high risk of VTE for an extended period after discharge.

For example, one academic study examined the medical records of approximately 11,000 acute medically ill patients for a period of 180 days after hospital admission and determined that 56.6% of VTE events in this population occurred after discharge. In the MAGELLAN trial sponsored by Bayer and Janssen, 5.7% of enoxaparin-treated patients experienced a significant thrombotic event during the trial period, and, in higher risk sub-populations, such event rate was 7% to 9%. In the ADOPT trial sponsored by BMS, the combined incidence of symptomatic VTE and VTE-related death was twice as high during the period after cessation of enoxaparin treatment as it was during the treatment period.

Currently, there are no anticoagulants approved for extended duration VTE prophylaxis in acute medically ill patients for more than a 14-day period, and most patients receive anticoagulation therapy only while in the hospital. Heparin and enoxaparin are generally not often used after hospital discharge due to the difficulty of administering the therapies and lack of data showing a benefit beyond the currently approved duration of therapy. Warfarin has not been studied in a large randomized trial and is not indicated for VTE prophylaxis in acute medically ill patients. Both rivaroxaban and apixaban have been evaluated in large Phase 3 trials of VTE prophylaxis in acute medically ill patients, both in the hospital and after discharge. The MAGELLAN trial, which evaluated rivaroxaban, demonstrated efficacy but failed to demonstrate an acceptable benefit-to-risk profile due to increased bleeding, and the ADOPT trial, which evaluated apixaban, showed a reduction in VTE events, but failed to demonstrate statistically significant efficacy. Importantly, the results of these trials showed that acute medically ill patients with restricted mobility and other risk factors treated with standard duration enoxaparin therapy for 6 to 14 days continue to be at increased risk of VTE post-hospital discharge for at least 35 days.

Leading clinicians have identified the lack of an appropriate therapy to prevent VTE in acute medically ill patients after discharge as a significant unmet clinical need. Such a therapy should be easy to administer both within and outside of the hospital setting and would need to show a robust reduction in the incidence of VTE and an acceptable bleeding profile compared to the current standard of care. The therapy would also need to have other properties appropriate for use in acute medically ill patients. These patients are typically frail and elderly and often cannot tolerate drugs that are significantly cleared through the kidneys. Moreover, they are often taking multiple medications for concomitant conditions and need a therapy that has a low potential to interact with other medications and a simple dosing regimen.

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Betrixaban for extended duration VTE prophylaxis in acute medically ill patients

We believe that Betrixaban is well suited for use in extended duration VTE prophylaxis in acute medically ill patients, both in the hospital and after discharge. Our preclinical and clinical studies suggest that it has antithrombotic activity similar to that of enoxaparin and certain other anticoagulants (dabigatran, an anti-thrombin drug and fXa inhibitors; rivaroxaban, apixaban and edoxaban). In addition, it has a number of characteristics that differentiate it from these compounds that we believe are particularly relevant to acute medically ill patients, including:

Betrixaban clinical experience

Betrixaban has been evaluated in 22 Phase 1 and Phase 2 clinical studies involving 1,411 human subjects, 1,200 of whom received Betrixaban, including more than 100 subjects for six months or more. A series of 19 Phase 1 and clinical pharmacology studies provided substantial information regarding its safety, dosage and use in specific sub-populations. In three Phase 2 studies, Betrixaban was evaluated in specific patient populations relative to commonly used anticoagulants. Consistent with the development of other antithrombotic agents, these studies were not designed to demonstrate a statistically significant difference between groups for the studied outcomes. The Betrixaban Phase 2 studies were instead designed to demonstrate evidence of an anticoagulant effect and relative safety compared to an established comparator. In these clinical studies:

As is typical in the development of anticoagulants, our initial Phase 2 study was conducted in patients undergoing elective total knee replacement surgery. This patient population has a very high incidence of VTE, making it an excellent population in which to evaluate the relative effectiveness and safety of different doses as compared to the standard of care. In our 215-patient EXPERT study, two different doses of Betrixaban, 15 mg and 40 mg each given twice daily, were evaluated against a U.S. standard twice-daily dose of 30 mg of enoxaparin in patients undergoing this surgery. The incidence of VTE in the Betrixaban groups was comparable to that in the enoxaparin group and lower than the rates historically observed in placebo groups, although these results were not statistically significant. In addition, the only incidence of major bleeding seen in the study was in the enoxaparin group.

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In our 508-patient Phase 2 EXPLORE-Xa study, we evaluated the use of Betrixaban for ischemic stroke prevention in elderly patients with nonvalvular atrial fibrillation. Three different once-daily doses of Betrixaban, 40 mg, 60 mg and 80 mg, were evaluated against dose-adjusted warfarin. Patients with a median age of 74 years received treatment for at least 90 days and as long as 12 months. The incidence of ischemic stroke, as well as major bleeds and clinically relevant non-major bleeds, was comparable across the warfarin and Betrixaban treatment groups, suggesting similar anticoagulant activity and bleeding risk acros s all groups. In addition, we measured D-dimer levels. D-dimer is a byproduct of coagulation, and elevated levels have been shown to be indicative of an increased risk of thromboembolism. In those patients receiving Betrixaban who had not previously been t aking warfarin, we observed a dose-related decrease in D-dimer levels. We believe the results of the EXPLORE-Xa study, although not statistically significant, provide evidence of the anticoagulant activity of Betrixaban and indicate that the long-term use of Betrixaban is well tolerated in an elderly population, including those with moderate to severe kidney disease.

Our Phase 2 DEC study evaluated the utility of adjusting the dose of Betrixaban based on a patient’s weight. The study indicated that making such adjustments is not necessary and it provided additional evidence of the safety and activity of Betrixaban.

All of our clinical studies to date have indicated that Betrixaban is well tolerated. Subjects taking Betrixaban had an increased rate of gastrointestinal issues, such as diarrhea, nausea and vomiting, as compared to subjects taking placebo, but these increased rates appear to be similar to those of patients taking other fXa inhibitors. Patients taking Betrixaban also had an increased incidence of other side effects such as back pain, dizziness, headaches, rashes and insomnia as compared with patients taking a placebo or an active comparator. These side effects do not appear to have a substantial impact on patients’ tolerance of Betrixaban. There is no evidence that Betrixaban has negative effects on heart rhythm or liver function. As discussed earlier, the most significant side effect of all anticoagulants is major bleeding. While definitive conclusions cannot be drawn from our Phase 2 studies, it does not appear from the study results that patients taking Betrixaban face a greater risk of major bleeding than patients taking warfarin or enoxaparin.

Clinical experience of fXa inhibitors in acute medically ill patients

Direct fXa inhibitors rivaroxaban and apixaban have been studied in large Phase 3 trials for VTE prophylaxis in acute medically ill patients. Neither trial was successful in showing a balanced result of VTE reduction relative to major bleeding events, referred to as net clinical benefit. The MAGELLAN trial, which evaluated rivaroxaban, met its primary efficacy endpoint of decreased VTE in acute medically ill patients but achieved this result with an unfavorable bleeding risk. By comparison, the ADOPT trial, which evaluated apixaban, did not demonstrate significant clinical efficacy, although the rates of VTE in its study population were significantly lower than those observed in MAGELLAN, which we believe reflects the lower risk patient population enrolled in ADOPT. Despite the lack of efficacy observed in ADOPT, the incidence of major bleeding was lower than that observed in MAGELLAN. Although neither MAGELLAN nor ADOPT was successful, both highlighted the continuing risk of VTE after hospital discharge and illustrated two major lessons that have informed the clinical development plan for Betrixaban for acute medically ill patients.

Dose selection : In the MAGELLAN trial, rivaroxaban was dosed once daily despite having a half-life of only between 5 to 9 hours. To achieve adequate therapeutic coverage in a once-daily regimen, MAGELLAN may have studied a rivaroxaban dose that produced supratherapeutic drug levels for a period after dosing, possibly explaining the unfavorable bleeding risk observed in that trial. In the ADOPT trial, apixaban with a half-life of 12 hours, was dosed twice daily in order to maintain more consistent drug levels, which may have been responsible for its relatively lower rate of bleeding than was seen in MAGELLAN.

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Patient selection : Multiple studies of the acute medically ill have demonstrated that VTE incidence increases as the number of risk factors that a patient has incre ases. In the ADOPT trial, where enrollment was open to a broad set of acute medically ill patients, including a large number of subjects who were not at high risk of VTE, there were too few VTE events to create a statistically significant separation betwee n the control and treatment arms. In contrast to ADOPT, MAGELLAN enrolled patients with higher levels of VTE risk and treatment with rivaroxaban produced a significant reduction in the 35-day incidence of VTE compared to standard of care treatment with eno xaparin. Neither MAGELLAN nor ADOPT excluded patients whose medical history or concurrent use of anti-platelet therapy placed them at a substantially higher risk of severe bleeding. In MAGELLAN, this failure to exclude certain high risk patients combined w ith the dosing regimen used may have contributed to the relatively high level of bleeding events observed in the trial and the lack of net clinical benefit.

Phase 3 APEX study

We believe that for an anticoagulant to demonstrate efficacy and safety for extended duration VTE prophylaxis in acute medically ill patients, it must have the right drug properties, be dosed at appropriate levels and target the right patient population. As discussed above, we believe that Betrixaban has a number of key pharmacokinetic and pharmacodynamic properties that make it well suited for use with the frail and elderly patients that comprise a significant portion of the acute medically ill patient population. In addition, using the data from our extensive clinical and preclinical studies of Betrixaban and learnings from ADOPT and MAGELLAN, we believe that we have designed APEX with a dosing regimen for a study population focused on patients with certain biomarkers, that we believe will increase the probability that Apex will demonstrate both safety and efficacy in VTE prophylaxis in acute medically ill patients both in the hospital and after discharge.

Dose selection . Based on standard pharmacometric modeling that integrated preclinical and clinical studies of fXa inhibitors, we believe that we have identified a dosing regimen (80 mg oral once-daily dose for 35 days following a 160 mg oral loading dose on day one; 40mg dose for patients with severe renal impairment) that will produce clinically meaningful anticoagulant effects in the APEX trial. In our clinical studies, we measured the concentration of Betrixaban achieved at different dose levels and observed in Phase 2 studies that at total daily doses of 30 mg and 80 mg Betrixaban had anticoagulant activity, measured by standard imaging tests to detect VTE, comparable to standard of care enoxaparin. We also observed that bleeding and anticoagulant activity, as measured by a common blood marker D-dimer, of once-daily 40 mg, 60 mg and 80 mg doses of Betrixaban were comparable to standard doses of warfarin in patients with non-valvular atrial fibrillation. We correlated those doses with levels of thrombin generation inhibition, a common pharmacodynamic measurement used to compare anticoagulant activity of different drugs, and compared those levels with those produced by other fXa inhibitors, including enoxaparin, rivaroxaban and apixaban. For patients with severe renal impairment and those taking agents that are strong inhibitors of PGP enzymes, the dose of Betrixaban will be reduced to 40 mg daily, which targets a level of anticoagulant activity consistent with the overall patient population.

The following diagram depicts pharmacometric modeling of thrombin generation inhibition over time for rivaroxaban, apixaban and Betrixaban, reflecting the dosing regimen used in MAGELLAN, ADOPT and APEX, respectively:

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Patient selection: efficacy . We used the findings of MAGELLAN, ADOPT and other trials to help define the population of patients that are more likely to demonstrate clinical ben efit from extended duration VTE prophylaxis to be included in APEX. APEX enroll ed patients that have a combination of specific medical conditions and risk factors that put them at an elevated risk of VTE for post-hospital discharge and thus a need for VTE prophylaxis during this period . The APEX inclusion criteria specify that patients must be admitted to the hospital with one of five categories of acute medical illness: heart failure, respiratory failure, infection, rheumatic disease or stroke. The inclusi on criteria also require that patients have a high degree of immobilization. Further, a patient must meet one of the following three additional criteria: be over 75 years of age, be over 60 years of age and have a D-dimer level of at least twice the upper limit of normal, or be over 40 years of age and have elevated D-dimer blood levels of at least twice the upper limit of normal and have at least one additional major risk factor for VTE.

Patient selection: safety . Consistent with our approach to enroll patients into the APEX study that are at an elevated risk for VTE for 35 days or more, we likewise designed the trial to exclude patients at high risk for bleeding. We believe this further increases the probability that APEX will demonstrate a net clinical benefit for Betrixaban. For example, we exclude patients with a historian admitting diagnosis which will likely require major surgery, gastrointestinal bleeding, hemorrhagic stroke or bleeding pulmonary lesions. In addition, patients taking daily doses of aspirin are limited to low doses and must also take a proton-pump inhibitor to reduce the risk of gastrointestinal bleeding.

Other study design features and operations measures. We have implemented various measures to improve data quality, ensure we maintain a high degree of statistical power and reduce confounding clinical and statistical issues compared to MAGELLAN and ADOPT. For example, we are transmitting ultrasound images electronically rather than by mail so that quality can be assessed in real time. We do not require an ultrasound at day 10, which was required in an earlier study and that we believe led to patients failing to return for a second ultrasound at day 35. We also instituted patient outreach measures intended to increase patient compliance with follow-up appointments after hospital discharge. We expect our approach to result in a relatively lower occurrence of missing data in the primary endpoint analysis and therefore increase study power and minimize potential bias for a given number of patients.

We designed our Phase 3 APEX study to demonstrate the safety and efficacy of Betrixaban for extended duration VTE prophylaxis during a hospital stay and post-discharge for 35 days in acute medically ill patients with restricted mobility and certain biomarkers and additional risk factors. If APEX is successful, we expect it to be sufficient to support global regulatory approvals. We can provide no assurance that APEX will be successful and, if APEX is not successful, our ability to commercialize Betrixaban would be materially adversely affected. APEX is a randomized, double-blind, double-dummy, active-controlled, multicenter, multinational study comparing a once-daily dose of 80 mg of Betrixaban for 35 days (including both in the hospital and after discharge) with in-hospital administration of 40 mg of enoxaparin once daily for 6 to 14 days followed by placebo for the remainder of the study period. In the third quarter of 2015, we completed a planned protocol defined sample size re-assessment and increased the size of the trial from 6,850 to approximately 7,500 patients. The increase in sample size was designed to ensure APEX statistical power for the primary efficacy analysis patient cohort and increases power in the overall patient population analysis. We have finalized our statistical analysis plan in agreement with the FDA. We completed APEX patient enrollment in the fourth quarter of 2015, and expect to report top line data in early April 2016 and, assuming positive trial data, we expect to file the NDA in the third quarter of 2016. In the fourth quarter of 2015, Betrixaban received Fast Track designation from the FDA for prevention of blood clots in acute medically ill patients.  Fast-Track designation is generally intended by the FDA to facilitate the development, and expedite the review, of drugs which treat a serious or life-threatening condition and fill an unmet medical need.

The primary APEX study objective is to demonstrate superiority of inpatient followed by post-hospitalization VTE prophylaxis with Betrixaban as compared to a current standard of care (enoxaparin given for VTE prophylaxis only during hospitalization) in the reduction of VTE-related events at 35 days while maintaining a favorable benefit to risk profile. The APEX study is adequately powered to show a clinically relevant benefit on the primary endpoint of occurrence of one or more of the following: asymptomatic proximal DVT (as detected by ultrasound), symptomatic DVT (proximal or distal), non-fatal PE, and VTE-related death.

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The following schematic depicts the APEX study design:

We believe that Betrixaban’s unique pharmacological profile combined with APEX’s study design positions Betrixaban to be the first novel anticoagulant approved for use in acute medically ill patient who require extended duration VTE prophylaxis. We anticipate that such an approval, if obtained, would be for the use of Betrixaban in those acute medically ill patients with medical profiles consistent with those of patients enrolled in APEX. Based upon a review of epidemiological data, we believe that such patients constitute approximately two thirds of the acute medically ill patient population subject to a medical guideline recommendation to receive pharmacological VTE prophylaxis, or approximately 14 million patients in the G7 countries.

Betrixaban pharmacoeconomics

Oral drugs are typically less expensive than injectable agents. Currently in thrombosis, based on our research, we estimate that the average daily wholesale acquisition cost of a 40 mg Lovenox pre-filled syringe in the United States is $33.08 compared to rivaroxaban at $10.49 per day for both the 10 mg and 20 mg strengths.  In addition, the cost to treat a VTE in a hospital setting in the United States can reach $16,500 per patient in direct medical expenses. Therefore, we believe that, if our APEX Phase 3 study is successful, Betrixaban could represent a cost-effective preventive therapy against VTE in acute medically ill patients as compared to the current standard of care. We estimate that by 2016, the total potential market for VTE prophylaxis in the acute medically ill population, including extended duration VTE prophylaxis, will be $3 billion to $4 billion.

Andexanet alfa

Major bleeding is the most clinically meaningful side effect of oral and injectable fXa inhibitors, including apixaban, rivaroxaban, edoxaban, Betrixaban and enoxaparin. Andexanet alfa is a recombinant protein designed to reverse anticoagulant activity in patients treated with a fXa inhibitor. Andexanet alfa has potential indications to treat patients’ anticoagulated with a direct or indirect fXa inhibitor when reversal of anticoagulation is needed, such as in life-threatening or uncontrolled bleeding or for emergency surgery/urgent procedures.

Overview of anticoagulant-related bleeding

In patients using anticoagulation therapy, there is an increased risk of major bleeding, which is common across all anticoagulants regardless of the reason for anticoagulation therapy, the patient setting or the duration of therapy. For patients at an elevated risk of thrombosis, the benefits provided by anticoagulation products generally outweigh the related risk of bleeding, however, major bleeding remains a significant cause of morbidity and mortality in these patients. For example, atrial fibrillation patients taking fXa inhibitors on a chronic basis had a 1% to 4% annual rate of a major bleed in the Phase 3 ARISTOTLE trial of apixaban, sponsored by BMS and Pfizer, and the Phase 3 ROCKET trial of rivaroxaban, sponsored by Bayer and Janssen. Based on other clinical trials, we believe that annually an additional 1% of patients taking fXa inhibitors will require emergency surgery. Patients on anticoagulation who suffer trauma have a higher risk of death than similar patients not on anticoagulation. The cost of treating a major bleed may exceed $100,000 in direct medical expenses.

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The current standard treatment for patients taking established anticoagulants who experience major bleeding is to administer products that directly or indirectly support clotting, such as Vitamin K; fresh frozen plasma, or FFP; prothrombin complex concentrates, or PCCs; protamine; and recombinant Factor VIIa, or rFVIIa. Which of these approaches is used for a given patient depends on the particular anticoagulant being taken. For example, common treatments for warfarin reversal are Vitamin K, FFP and, more recently, PCCs, while low molecular weight heparin patients needing reversal are often managed with FFP or protamine. While the existing reversal agents are effective to varying degrees to reverse the effects of established anticoagulants, they can have potentially serious side effects, including in some cases increased risk of prothrombotic effects such as ischemic stroke and myocardial infarction.

There are, however, no approved antidotes or reversal agents for the new oral fXa inhibitors. Moreover, the reversal agents used for established anticoagulants have not been extensively studied in clinical trials of oral fXa inhibitor treated patients, and preliminary data suggest that they may not be effective to treat major bleeding in these patients. The existing reversal agents work mostly in the early steps of the coagulation cascade prior to the involvement of fXa and simply supplement the factor deficiency caused by established anticoagulants. For the reversal agents to affect bleeding in patients taking oral fXa inhibitors, sufficiently large quantities would need to be given to overwhelm the inhibitor, an approach that we believe could lead to dangerous prothrombotic effects. As there are no currently approved therapies designed to reverse or overcome fXa inhibitors, patients taking those therapies face a risk of major bleeding. Leading clinicians have identified, and the FDA has recognized, the lack of a reversal agent for fXa inhibitors as a significant unmet clinical need.

The following diagram depicts where the existing reversal agents and novel oral anticoagulants interact with the coagulation cascade:

Despite the risk of major bleeding, sales of fXa inhibitors are expected to increase dramatically in the coming years as they have significant clinical benefits over standard products for preventing thrombosis, such as warfarin or enoxaparin. Based on our research and relevant market data, we estimate that by 2020, fXa inhibitors will have a majority share of the market in each major anti-coagulation indication. As sales of fXa inhibitors increase, the need for an effective antidote or reversal agent will correspondingly increase. We estimate that by 2020, over 500,000 patients annually in the G7 will need a fXa reversal agent, with approximately 300,000 of these cases arising from a major bleeding episode, approximately 100,000 of these cases arising from emergency surgery and approximately 100,000 of those cases arising from traumatic injury.

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Andexanet alfa — a universal antidote for f Xa inhibitors

Building on the insights gained during the development of Betrixaban, we designed Andexanet alfa as a universal reversal agent for direct fXa inhibitors, such as rivaroxaban, apixaban, edoxaban and Betrixaban, as well as indirect fXa inhibitors, such as enoxaparin. Andexanet alfa is structurally very similar to native fXa, but it has a number of limited modifications intended to restrict its biological activity to reversing the effects of fXa inhibitors. Andexanet alfa acts as a fXa decoy that binds to fXa inhibitors in the blood. Once bound to Andexanet alfa, the inhibitors are unable to bind to and inhibit native fXa. The native fXa then becomes available to participate in the coagulation process and restore hemostasis, or normal clotting.

In designing Andexanet alfa, we started with native fXa protein and used our knowledge of its functional domains to make three changes by protein engineering. First, we made a small modification to the active site, or catalytic pocket, of native fXa so that Andexanet alfa cannot drive the coagulation process but still binds to fXa inhibitors with high affinity. Second, we removed most of the section of the native fXa that facilitates binding to the thrombin activating complex to reduce the risk that Andexanet alfa would interfere with the activity of native fXa. Importantly, while removing this section we retained a small portion at the end so that Andexanet alfa looks more like native fXa to the immune system, thereby decreasing the likelihood of an immune system response against Andexanet alfa. Third, we made a minor modification in the peptide section that links the two parts of fXa to facilitate Andexanet alfa’s manufacture using standard processes. The end result is a recombinant protein that we believe can bind with and sequesters any direct or indirect fXa inhibitor, thereby allowing native fXa to drive coagulation and restore hemostasis.

Andexanet alfa preclinical results

We have evaluated Andexanet alfa in numerous in-vitro and animal studies and have developed substantial evidence regarding the safety, efficacy and rapid activity of Andexanet alfa. Key findings from this preclinical program include:

Taken together, these and other studies suggest, but do not prove, that Andexanet alfa will be a safe and effective fXa reversal agent.

Andexanet alfa clinical results and development strategy

In November 2013, the FDA granted breakthrough therapy designation for Andexanet alfa and we are pursuing an Accelerated Approval pathway for Andexanet alfa. Typically the FDA requires at least one large-scale, randomized, placebo controlled study for the approval of a new therapeutic. However, under the FDA’s Accelerated Approval pathway, therapies targeting a significant unmet clinical need may be approved based upon their showing adequate safety as well as efficacy against a surrogate biomarker endpoint in a clinical trial. Utilizing this expedited approval process should significantly decrease the time and expense associated with our development program. In February 2015, the FDA granted orphan drug designation to Andexanet alfa.

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We have completed a series of Phase 2 studies and two Phase 3 studies (ANNEXA - Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of f Xa Inhibitors) studies using biomarker endpoints for Andexanet alfa . These biomarkers include anti- f Xa levels, plasma free fraction of the anticoagulant and thrombi n generation. We are currently evaluating Andexanet alfa in a Phase 2 proof-of-concept study with Betrixaban and a Phase 4 confirmatory study . The results from our Phase 3 studies along with data from a limited number of patients in the ongoing Phase 4 confirm atory study were included in our BLA filing in the f irst quarter of 201 6 . In the second half of 2014, we obtained formal scientific advice from the EMA that we believe supports using the same c linical data package for submitting for regulatory appro val in Europe. We have entered into collaboration agreements with BMS and Pfizer, and Bayer to obtain the right to pursue final regulatory approval and commercialize Andexanet alfa in Japan.

Andexanet alfa Phase 2 studies

We have completed a series of Phase 2 proof-of-concept studies evaluating the safety and activity of Andexanet alfa in healthy volunteers who were administered one of several fXa inhibitors. The purpose of these studies is to evaluate the safety of Andexanet alfa and to determine the dose of Andexanet alfa required to reverse the effect of each anticoagulant as measured by multiple pharmacokinetic and pharmacodynamic endpoints.  Results from our Phase 2 studies with apixaban, rivaroxaban, edoxaban and enoxaparin, demonstrated a bolus of Andexanet alfa immediately reversed the anticoagulation activity of each fXa inhibitor and that the reversal could be sustained with a continued infusion of Andexanet alfa.  Andexanet alfa was shown to be well tolerated with no thrombotic events or antibodies to fXa or Factor X detected.

In these studies the fXa inhibitor was dosed in healthy volunteers for five or six days to achieve steady-state drug levels.  Andexanet alfa was then administered intravenously in a range of bolus only and bolus plus infusion dose regimens. Pharmacodynamic and safety data were collected through Day 48 with pharmacokinetic data through Day 10.  The primary endpoint for each of these studies is the percent reversal of anti-fXa activity after dosing.  

In the Phase 2 studies Andexanet alfa was generally well tolerated with no apparent safety signals. Importantly, none of the subjects receiving Andexanet alfa generated detectable levels of antibodies against either Factor X or fXa and there have been no neutralizing antibodies against Andexanet alfa detected. The most common drug-related side effect was mild infusion-related reactions, which are not unexpected for a biological agent, such as Andexanet alfa. In the Phase 2 studies, there was also a dose-dependent restoration of thrombin generation with no clinical evidence of thrombosis.

Phase 3 ANNEXA-A (Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of fXA Inhibitors – Apixaban) Study Design and Results

The randomized, double-blind, placebo-controlled Phase 3 ANNEXA-A study is evaluating the safety and efficacy of Andexanet alfa in reversing apixaban-induced anticoagulation in older healthy volunteers. Efficacy is being evaluated using biomarker endpoints, including anti-fXa levels as the primary endpoint. Secondary endpoints include levels of plasma unbound (free fraction) of apixaban and thrombin generation.

In the first part of the Phase 3 ANNEXA-A trial, 33 healthy volunteers (ages 50 to 73) were given apixaban 5 mg twice daily for 3.5 days and then randomized in a 3:1 ratio to Andexanet alfa administered as a 400 mg IV bolus (n=24) or to placebo (n=9). The study achieved all of its primary and secondary endpoints with statistical significance (p value <0.0001). In the study, two to five minutes after completion of a bolus dose of Andexanet alfa, the anticoagulant activity of apixaban was reversed by approximately 94 percent (p value <0.0001) compared with placebo as measured by anti-fXa activity. Every subject treated with Andexanet alfa had between 90 and 96 percent reversal of the anticoagulant activity of apixaban. The reversal of anti-fXa activity correlated with a significant reduction in the level of free, unbound apixaban in the plasma, consistent with the mechanism of action of Andexanet alfa. Additionally, Andexanet alfa restored thrombin generation to baseline normal levels (prior to apixaban therapy) in 100 percent of subjects (p<0.0001 vs. placebo). In this study, no serious adverse events, thrombotic events, or antibodies to Factor X or Xa were reported following Andexanet alfa administration. Mild infusion reaction was reported in three subjects.  

In the second part of the ANNEXA-A study, 31 healthy volunteers were given apixaban 5 mg twice daily for four days and then randomized in a 3:1 ratio to receive either andexanet alfa administered as a 400 mg IV bolus followed by a continuous infusion of 4 mg/min for 120 minutes (n=24) or placebo (n=8). Andexanet alfa significantly reduced anti-fXa activity by 92 percent compared with placebo (p<0.0001), with reversal persisting for 1 to 2 hours after completion of the infusion. The reduction in free unbound apixaban was sustained with the bolus plus infusion, which significantly reduced the mean plasma concentration of free unbound apixaban compared with placebo (p=0.0002). Andexanet alfa also restored thrombin generation to normal in all subjects who received the compound (p<0.0001 vs. placebo). In this study, Andexanet alfa was well tolerated. No serious or severe adverse events, no thrombotic events, and no antibodies to Factor X or Xa were reported. All adverse events related to Andexanet alfa administration were non-serious and mild.

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The following diagram depicts the data from the second part of our Phase 3 ANNEXA-A study of Andexanet alfa in subjects taking apixaban.

Phase 3 ANNEXA-R (Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of FXa Inhibitors – Rivaroxaban) Study Design and Results

The randomized, double-blind, placebo-controlled Phase 3 ANNEXA-R study is evaluating the safety and efficacy of Andexanet alfa in reversing rivaroxaban-induced anticoagulation in healthy volunteers ages 50 to 75 years. Efficacy is being evaluated using biomarker endpoints, with anti-fXa levels as the primary endpoint. Secondary endpoints include plasma levels of plasma unbound (free fraction) of rivaroxaban and thrombin generation levels.

In the first part of the ANNEXA-R study, 41 healthy volunteers were given rivaroxaban 20 mg once daily for four days and then randomized in a 2:1 ratio to receive at Cmax either Andexanet alfa administered as an 800 mg IV bolus (n=27) or to placebo (n=14). The study achieved its primary endpoint with high statistical significance. Within two to five minutes of completion of the bolus dose, Andexanet alfa significantly reversed the anticoagulant activity of rivaroxaban (by 92 percent) compared with placebo (p<0.0001), as measured by anti-fXa activity; significantly reduced the level of free (unbound) rivaroxaban in the plasma compared with placebo (p<0.0001); and fully restored thrombin generation in 96 percent of subjects (p<0.0001 vs. placebo). Andexanet alfa was shown to be well tolerated.

In the second part of the ANNEXA-R study, 39 healthy volunteers were given rivaroxaban 20 mg once daily for four days and then randomized in a 2:1 ratio to receive either Andexanet alfa administered as an 800 mg IV bolus followed by a continuous infusion of 8 mg/min for 120 minutes (n=26) or placebo (n=13). Andexanet alfa significantly reduced anti-fXa activity by 97 percent compared with placebo (p<0.0001), with reversal persisting for 1 to 2 hours after completion of the infusion. The reduction in free unbound rivaroxaban was sustained with the bolus plus infusion, which significantly reduced the mean plasma concentration of free unbound rivaroxaban compared with placebo (p<0.0001). Andexanet alfa also restored thrombin generation to normal in all subjects who received the compound (p<0.0001 vs. placebo).

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The following diagram depicts the data from the second part of our Phase 3 ANNEXA- R study of Andexanet alfa in subjects taking rivarox aban.

Our Phase 4 ANNEXA-4 study, which was initiated in early 2015, is an open-label, single-arm study being conducted in patients receiving apixaban, rivaroxaban, edoxaban or enoxaparin (a low molecular weight heparin) who present with an acute major bleed. Acute major bleeding includes life-threatening bleeding, bleeding associated with very low blood counts, or bleeding that occurs in a critical area such as the brain or surrounding the heart. The trial excludes bleeding due to major trauma and large blood vessel rupture. Patients will receive Andexanet alfa as an intravenous (IV) bolus followed immediately by a continuous infusion. The study is evaluating Andexanet alfa’s ability to decrease anti-fXa activity and restore hemostasis in patients. Safety endpoints include overall 45 day safety, including an evaluation of thrombotic activity and antibody development. Data from a small number of patients in this study was included in our BLA filing in the first quarter of 2016 as part of an Accelerated Approval pathway for Andexanet alfa.

If the registration studies are successful, we believe these data could be sufficient to obtain approval for Andexanet alfa from the FDA and the EMA.

Collaboration with BMS and Pfizer

In October 2012, we entered into a three-way agreement with BMS and Pfizer to include subjects dosed with apixaban, their jointly owned product candidate, in one of our Phase 2 proof-of-concept studies of Andexanet alfa. The total consideration under this agreement of $6.0 million was received and recognized as revenue on a straight-line basis over the estimated performance period through the fourth quarter of 2013. This agreement will continue in force until our anticipated meeting with the FDA or termination by either party pursuant to the agreement. BMS and Pfizer may terminate this agreement if the parties cannot agree on certain changes to the development plan, for convenience with 60 days’ advance written notice or for our bankruptcy or change of control. In addition, either party may terminate this agreement for the other party’s uncured material breach or for material safety issues.

In January 2014, we entered into a second collaboration agreement with BMS and Pfizer to further study the safety and efficacy of Andexanet alfa as a reversal agent to apixaban in our Phase 3 studies.  Under the terms of the agreement, we received an upfront payment of $13.0 million and are eligible to receive additional development and regulatory milestone payments of up to $12.0 million. These payments represent the total consideration under this agreement. BMS and Pfizer will continue to provide development and regulatory guidance for the program.

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This Phase 3 collaboration agreement will continue in force until the approval of Andexanet alfa as a reversal agent for apixaban by the FDA and EMA.  BMS and Pfizer may terminate this agreement for convenience with 60 days’ advance written notice or for our bankruptcy or change of control. In addition, either party may terminate this agreement for the other party’s unc ured material breach, material safety issues, or failure of the Phase 3 studies.

In January 2016, we entered into collaboration agreements with BMS and Pfizer to obtain the right to pursue final regulatory approval and commercialize Andexanet alfa as a reversal agent in Japan.

Collaboration with Bayer and Janssen

In February 2013, we entered into a three-way agreement with Bayer and Janssen to include subjects dosed with rivaroxaban, their fXa inhibitor product, in one of our Phase 2 proof-of-concept studies of Andexanet alfa. We are responsible for the cost of conducting such clinical studies. Pursuant to the agreement, Bayer and Janssen will work closely with us on both development and regulatory aspects of Andexanet alfa in connection with our Phase 2 proof-of-concept studies. Under the agreement, Bayer and Janssen have each provided us with an upfront and non-refundable fee of $2.5 million, for an aggregate fee of $5.0 million, and will each provide us with an additional payment of $250,000, for an aggregate fee of $500,000, following the delivery of the final written study report of our Phase 2 proof-of-concept studies of Andexanet alfa, as further specified in the agreement. This agreement will continue in force until the later of the completion of the studies and the fulfillment of certain other conditions set forth in the agreement, unless earlier terminated by either party pursuant to the agreement. This agreement may be terminated by either party for material safety issues or the other party’s uncured material breach. In addition, Bayer and Janssen may terminate this agreement with 60 days’ advance written notice for convenience at any time, or immediately for our bankruptcy or change of control.

In February 2014, we entered into a second collaboration agreement with Bayer and Janssen to further study the safety and efficacy of Andexanet alfa as a reversal agent to rivaroxaban through our Phase 3 studies. Our original collaboration agreement with Bayer and Janssen covers the conduct of a Phase 2 proof-of-concept study. The second collaboration agreement covers the conduct of Phase 3 studies of Andexanet alfa with rivaroxaban and any potential U.S. and EU regulatory approval of Andexanet alfa as reversal agent of rivaroxaban. The Phase 3 studies are ongoing. Under this Phase 3 collaboration agreement, we received an upfront payment of $10.0 million and are eligible to receive additional development and regulatory milestone payments of up to $15.0 million. These payments represent the total consideration under this agreement. Bayer and Janssen will continue to provide development and regulatory guidance for the program.

This Phase 3 collaboration agreement will continue in force until the approval of Andexanet alfa as a reversal agent for rivaroxaban by the FDA and EMA.  Bayer and Janssen may terminate this agreement for convenience with 60 days’ advance written notice or for our bankruptcy or change of control.  In addition, either party may terminate this agreement for the other party’s uncured material breach or material safety issues or we can also terminate this agreement for failure of the Phase 3 studies.

In January 2016, we entered into collaboration agreements with Bayer to obtain the right to pursue final regulatory approval and commercialize Andexanet alfa as a reversal agent in Japan.

Collaboration with Daiichi Sankyo

In June 2013, we entered into an agreement with Daiichi Sankyo, to include subjects dosed with edoxaban, Daiichi Sankyo’s fXa inhibitor product, in one of our proof-of-concept studies of Andexanet alfa. We are responsible for the cost of conducting this clinical study. Under the terms of the agreement, Daiichi Sankyo provided us with an upfront fee of $6.0 million. Daiichi Sankyo may terminate the agreement at any time. We are obligated to perform preclinical proof-of-concept studies and participate on a JCC with Daiichi Sankyo to oversee the collaboration activities under the agreement. The total non-contingent consideration under this agreement of $3.0 million was fully recognized as revenue on a straight-line basis over the estimated non-contingent performance period through the first quarter of 2014. In February 2014, we resolved the contingent portion of the arrangement which was tied to pre-clinical studies. The contingent consideration under this agreement of $3.0 million is being recognized over the remaining estimated period of performance through the first quarter of 2015.

In July 2014, we entered into a second collaboration agreement with Daiichi Sankyo to evaluate Andexanet alfa as a reversal agent for the oral fXa inhibitor edoxaban through Phase 3 studies.  The second collaboration agreement covers the conduct of Phase 3 studies of Andexanet alfa with edoxaban and any potential U.S. and EU regulatory approval of Andexanet alfa as a reversal agent for edoxaban.  Under this Phase 3 collaboration agreement we received an upfront payment of $15.0 million and are eligible to receive additional development and regulatory milestone payments of up to $25.0 million.  These payments represent the total consideration under this agreement.  Daiichi Sankyo will continue to provide development and regulatory guidance for the program.

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This Phase 3 collaboration agreement w ill continue in force until the approval of Andexanet alfa as a reversal agent for edoxaban by the FDA and EMA.   Daiichi Sankyo may terminate this agreement for convenience with 60 days’ advance written notice or for our bankruptcy or change of control.  I n addition, either party may terminate this agreement for the other party’s uncured material breach or material safety issues, and we can also terminate this agreement for failure of the Phase 3 studies.

Andexanet alfa pharmacoeconomics

Major bleeding is the most clinically relevant side effect of anticoagulant treatment across all anticoagulants and clinical settings. Clinical trial results suggest that the frequency of major bleeding associated with the administration of fXa inhibitors ranges from 1% to 4% per year, depending on the underlying medical condition and the specific fXa inhibitor. The clinical costs of a major bleeding event in fXa inhibitor treated patients are estimated to be $28,000 per patient on average and $135,000 per patient for the top 10%. Based on the frequency of bleeding rates suggested by clinical trials and our projection of 36 million to 43 million patients treated annually with fXa inhibitors in the G7 countries, we believe that by 2020, the annual costs to the healthcare system to treat major bleeding episodes in patients treated with a fXa inhibitor may exceed $10 billion. We believe that an effective fXa antidote represents a potentially cost-effective way to manage these healthcare system costs.

Our hematologic cancer and inflammation product candidates

Our early stage development programs are focused on developing small molecule kinase inhibitors for the treatment of hematologic cancers and inflammatory diseases. Kinases are enzymes that act on and modify the activity of different proteins. Syk and JAK are clinically validated kinase targets involved in key signaling pathways that are important in certain hematologic cancers and inflammatory disorders. We have focused on the discovery and development of specific inhibitors of Syk and dual inhibitors of both Syk and JAK based on the unique roles of these kinases in NHL, CLL, allergic asthma, rheumatoid arthritis, or RA, and other inflammatory diseases.

Syk overview

Syk is a cell signaling enzyme that is found in certain white blood cells, including B-cells, basophils, neutrophils, monocytes, and tissue macrophages and mast cells, and is important for controlling the activity and recruitment of these cells. Scientists have focused on the role of Syk in B-cell cancers, such as NHL and CLL, as well as certain inflammatory diseases, such as allergic asthma and RA. B-cell activation is driven by the B-cell receptor, or BCR, whose signaling promotes cell proliferation, adhesion and survival in NHL and CLL. Syk acts downstream of the BCR, and blocking Syk activity in preclinical models results in an inhibition of proliferation, a disruption of tumor cell adhesion and cell death in malignant B-cells. Inhibitors of the BCR pathway, including the Syk inhibitor fostamatinib being developed by Rigel Pharmaceuticals, Inc. and the Syk inhibitor entospletinib being developed by Gilead Sciences, Inc., or Gilead, have been shown to have activity in NHL and CLL

JAK overview

The JAK kinases are a family of related tyrosine kinases that play key roles in cytokine signaling involved in immune processes. JAK activation and signaling is directly downstream from receptors for several cytokines that are integral to normal lymphocyte activation, proliferation and function. JAK also plays a role in malignant lymphocytes, including the survival and proliferation of CLL cells as well as cytokine signaling in certain NHL and other cancers. Leading clinicians have hypothesized that these JAK-related cytokines play a key role in promoting tumor survival and growth and that JAK inhibition may be effective in interrupting signaling processes involved in tumor cells that have mutated and are no longer entirely dependent on B-cell signaling via BCR.

Cerdulatinib—dual Syk/JAK inhibitor

The lead compound in our kinase development effort, Cerdulatinib, is a potent inhibitor of both Syk and JAK. We believe that Cerdulatinib may be able to treat certain diseases that involve Syk-BCR signaling and cytokine-JAK signaling. Based on the inhibition of these key pathways, we are currently focused on developing Cerdulatinib for NHL, CLL and other hematologic cancers, with a focus on patients with certain treatment-resistant mutations, including those targeting the BTK and PI3K kinases, and certain inflammatory diseases. We are currently conducting a Phase 1/2a proof-of-concept study of Cerdulatinib in NHL, and CLL, patients. In the Phase 1 dose escalation portion of the study, we have yet to reach the maximum tolerated dose and enrollment continues. We are exploring alternate dosing regimens and formulations to get a higher exposure of Cerdulatinib in patients.  Based on interim Phase 1 data we plan to advance Cerdulatinib into the Phase 2a portion of the study in 2016 which includes expansion cohorts in select hematologic cancers.

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NHL and CLL

Lymphoma is a large class of hematologic cancer that affects the B-cell and T-cell lymphocytes in lymph nodes. In 2015, lymphoma affected an estimated 760,000 people in the United States, with 580,000 of them suffering from the NHL varieties of the disease. NHL is often aggressive, marked by rapidly growing tumors in the lymph nodes, spleen, liver, bone marrow and other organs.

CLL is also a hematologic cancer that affects B-cell lymphocytes in the blood and bone marrow and is the most common type of leukemia. In 2011, approximately 100,000 patients had CLL in the United States. As it advances, usually slowly, CLL results in swollen lymph nodes, spleen and liver and eventually in anemia and infections.

Despite the introduction of novel therapies for B-cell NHL and CLL, some patients fail to go into remission and of those who do attain remission, many relapse and develop refractory disease and therefore need alternative therapies. The heterogeneity and severity of B-cell malignancies may warrant simultaneous targeting of multiple disease-relevant pathways. Dual inhibition of Syk and JAK represents such a strategy and may have several benefits relative to selective kinase inhibition, such as gaining control over a broader array of disease etiologies, reducing the probability of selection of alternate disease growth mechanisms, and the potential that an overall lower level suppression of multiple targets may be sufficient to modulate disease activity.

Cerdulatinib is a highly potent inhibitor of Syk and JAK activity in blood cells from human volunteers. In preclinical studies, inhibition of Syk and JAK, via Cerdulatinib, was active in a broad panel of B-cell lymphoma cell lines. Cerdulatinib was more effective than Syk-specific inhibition in these cell lines, suggesting that Cerdulatinib may be useful in the treatment of a broad range of B-cell lymphomas, including patients with diffuse large B-cell lymphoma, or DLBCL, an aggressive form of NHL that affects over 80,000 patients in the G7 countries, and patients with hard to treat mutations. For example, Cerdulatinib was shown to be effective in cell lines dependent on NFkB mutations for their survival. Current therapies and those in development, including those targeting the BTK and PI3K kinases, have limited activity in DLBCL patients with these mutations. In addition, preclinical data suggest that dual Syk/JAK inhibition with Cerdulatinib may also have activity in patients with an inadequate response to novel specific kinase inhibitors in development for NHL and CLL. Our strategy includes targeting Cerdulatinib for certain CLL and NHL patient populations, such as those with specific genetic mutations or those who have not responded adequately to other treatments. For example, it is estimated that approximately one third of patients become refractory to standard CLL therapy. We believe these indications could potentially represent a significant commercial opportunity if we are able to develop an effective therapy.

Based on the preclinical data and our understanding of the role of Syk and JAK signaling in B-cell cancers, we initiated an open label Phase 1/2a proof-of-concept study in October 2013 in NHL and CLL patients who have failed or relapsed on existing marketed therapies or products in development, including patients with identified mutations. In the Phase 1 dose escalation portion of the study, we have yet to reach the maximum tolerated dose, and enrollment continues. Interim results from the Phase 1 dose-escalation portion of the study demonstrated that Cerdulatinib is active and well tolerated, including patients who have received prior BTK and P13K inhibitor therapies. We are exploring alternate dosing regimens and formulations to get a higher exposure. Based on interim Phase 1 data, we plan to advance Cerdulatinib to the Phase 2a portion of the study, which includes expansion cohorts in select hematologic cancers. Depending on the overall results of the study, we would expect to further study Cerdulatinib in CLL and/or NHL either alone or in combination with other approved products or with other drugs in development.

Selective Syk inhibitors

Syk is an important mediator of immune response in a number of different types of immune cells. Ora is leading the pre-clinical study of a selective Syk inhibitor for allergic conjunctivitis.

In May 2015, our Biogen Idec agreement was terminated in its entirety, and we entered into a license and collaboration agreement with Ora pursuant to which we granted Ora an exclusive license to co-develop and co-commercialize one of our specific Syk inhibitors, PRT02761, which is currently in a pre-clinical study targeting allergic conjunctivitis. Ora has the primary responsibility for conducting the research and development and regulatory activities under this agreement. We are obligated to provide assistance in accordance with the agreed-upon development plan, as well as participate on various committees.

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Sales and marketing

Assuming Betrixaban and Andexanet alfa are approved by the FDA and other regulatory authorities, we intend to commercialize both molecules using a hospital-based sales force in the United States, and possibly marketing in other major markets. To achieve global commercialization, we anticipate using a variety of distribution agreements and commercial partnerships in those territories where we do not establish a sales force. We expect to target our U.S. sales and marketing efforts at the approximately 1,500 hospitals and out-patient acute care settings that would account for the large majority of the prescribing base for our product candidates, if approved. We plan to commercialize both of our thrombosis product candidates in the U.S. with a hospital-based sales force of approximately 100 to 150 sales representatives. We expect that our commercial infrastructure would be comprised of several proven, experienced marketing and sales management professionals along with a reimbursement support and hospital formulary specialist team. In addition, we intend to develop and publish health economic models demonstrating the value of Betrixaban and Andexanet alfa to hospital administrators and third party payors.

Research and development

We invest significant effort defining and refining our research and development process and internally teaching our approach to drug development. We favor programs with early decision points, well-validated targets, predictive preclinical models and clear paths to regulatory approval, all in the context of a target product profile that can address significant unmet or underserved clinical needs. Members of our discovery, research and development team have played central roles in discovering and developing a number of promising candidates over the past 20 plus years while at Portola, and while at Millennium Pharmaceuticals, Inc., or Millennium, and COR Therapeutics, Inc., two early developers of thrombosis therapies. They have used unique biological insights to develop in vitro and in vivo models that speed development. We also selectively leverage outside collaborators to expand into potential additional indications. As our product candidates progress through clinical development, we have focused and will increasingly focus our scientific efforts on supporting that development.

We emphasize data-driven decision making, strive to advance or terminate projects early based on clearly defined go/no go criteria, prioritize programs at all stages and allocate our capital to the most promising programs. Our current development-stage portfolio consists of three compounds discovered through our internal research efforts and one discovered by Portola scientists during their time at a prior company. In addition we are actively seeking to identify attractive external opportunities. We utilize the same critical filters for investment when evaluating external programs as we do with our own, internally-derived candidates.

Collaboration and license agreements

Betrixaban

Millennium agreements

In November 2003, we entered into an asset purchase agreement to acquire patent rights and intellectual property to an ADP Receptor Antagonist Program, or the ADP Program, and a Platelet Research Program from Millennium. We are obligated to pay to Millennium royalties at tiered single-digit percentages of net sales of certain ADP Program products if product sales are ever achieved, which royalty payments will continue until the expiration of the relevant patents or ten years after launch, whichever is later.

In August 2004, we entered into an agreement to license from Millennium certain exclusive rights to research, develop and commercialize certain compounds that inhibit fXa, including Betrixaban, or the fXa Program. The license agreement requires us to make certain license fee, milestone, royalty and sublicense sharing payments to Millennium as we develop, commercialize or sublicense Betrixaban and other products from the fXa Program. The Millennium license agreement further provides for additional payments to Millennium of up to $35.0 million based on the achievement of regulatory filing and approval milestones related to the fXa Program. In addition, we are obligated to pay Millennium royalties at tiered single-digit percentages of net sales of any fXa Program products if product sales are ever achieved. This license agreement will continue in force, on a product-by-product and country-by-country basis, until the expiration of the relevant patents or ten years after the launch, whichever is later, or termination by either party pursuant to the agreement. This license agreement may be terminated by either party for the other party’s uncured material breach. In addition, we may terminate this agreement for convenience with 30 days’ advance written notice.

In December 2005, we amended both the asset purchase agreement for the ADP Program and the license agreement for the fXa Program. In connection with this amendment, we have made aggregate cash payments to Millennium of $6.0 million and issued to Millennium equity securities with an aggregate value of $1.8 million through December 31, 2015.

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Lee’s agreement

In January 2013, we entered into a clinical collaboration agreement with Lee’s to jointly expand our Phase 3 APEX study of Betrixaban into China. Under the agreement, Lee’s provided us with an upfront and non-refundable payment of $700,000 and agreed to reimburse our costs in connection with the study to support the expansion of the APEX study into China. Lee’s also agreed to lead regulatory interactions with China’s State Food and Drug Administration for the study. We granted Lee’s an exclusive option to negotiate for the exclusive commercial rights to Betrixaban in China, which may be exercised by Lee’s for 60 days after it receives the primary data analysis report from the study. We may, at any time prior to the unblinding of the APEX study data, terminate the option and the agreement by providing Lee’s with written notification and making a termination payment. We reserved the right to terminate Lee’s option under certain specified circumstances. If the parties fail to reach agreement on the terms of the commercial rights and we commercialize Betrixaban in China ourselves or grant a third party the right to do so, or if we terminate Lee’s option under the agreement, we are required to make certain payments to Lee’s.

Unless earlier terminated, this agreement will continue until superseded by the execution of the agreement that grants to Lee’s the commercial rights to Betrixaban in China. This agreement may be terminated by Lee’s for convenience with 90 days’ advance written notice, or by either party for the other party’s uncured material breach or any material safety issue of Betrixaban. In addition, this agreement will automatically terminate if we fail to reach agreement to grant Lee’s the commercial rights to Betrixaban in China, or if we terminate Lee’s option. We completed APEX enrollment before the parties were able to find a regulatory pathway to expand the study into China.

Andexanet alfa

BMS and Pfizer agreements

In October 2012, we entered into a collaboration agreement with BMS and Pfizer, to include subjects dosed with apixaban, their jointly owned product candidate, in one of our Phase 2 proof-of-concept studies of Andexanet alfa. We are responsible for the cost of conducting such clinical studies. This agreement will continue in force until the completion of the studies or termination by either party pursuant to the agreement.

In January 2014, we entered into a second collaboration agreement with BMS and Pfizer to further study the safety and efficacy of Andexanet alfa as a reversal agent to apixaban through our ongoing Phase 3 studies. Under the terms of the Phase 3 agreement, we received an upfront payment of $13.0 million and are eligible to receive additional development and regulatory milestone payments of up to $12.0 million. These payments represent the total consideration under this agreement. BMS and Pfizer will continue to provide development and regulatory guidance for the program.

This Phase 3 collaboration agreement will continue in force until the approval of Andexanet alfa as a reversal agent for apixaban by the FDA and EMA.  BMS and Pfizer may terminate this agreement for convenience with 60 days’ advance written notice or for our bankruptcy or change of control. In addition, either party may terminate this agreement for the other party’s uncured material breach, material safety issues, or failure of the Phase 3 studies.

In January 2016, we entered into collaboration agreements with BMS and Pfizer to obtain Japanese regulatory approval and commercialize Andexanet alfa in Japan. Under the terms of the agreement we will receive an upfront payment of $15.0 million and are eligible to receive potential regulatory and sales-based milestone payments totaling $90.0 million, as well as double-digit royalties based on Andexanet alfa net sales in Japan. BMS and Pfizer will be responsible for all development and regulatory activities for Andexanet alfa in Japan and for commercializing the drug in Japan.

Bayer and Janssen agreements

In February 2013, we entered into a clinical collaboration agreement with Bayer and Janssen to include subjects dosed with rivaroxaban, their fXa inhibitor product, in one of our Phase 2 proof-of-concept studies of Andexanet alfa. We are responsible for the cost of conducting such clinical studies. This agreement will continue in force until the later of the completion of the studies and the fulfillment of certain other conditions set forth in the agreement, unless earlier terminated by either party pursuant to the agreement.

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In February 2014, we entered into a second collaboration agreement with Bayer and Janssen to further study the safety and efficacy of Andexanet alfa as a reversal agent to rivaroxaban through our ongoing Phase 3 studies. Our original collaboration agreement with Bayer and Janssen covers the conduct of a Phase 2 proof-of-concept study. The second collaboration agreement cover s the conduct of Phase 3 studies of Andexanet alfa with rivaroxaban and any potential U.S. and EU r egulatory approval of Andexanet alfa as reversal agent of rivaroxaban. Under this Phase 3 collaboration agreement, we receive d an upfront payment of $10 million and are eligible to receive additional development and regulatory milestone payments of up to $ 15.0 million. These payments represent the total consideration under this agreement. Bayer and Janssen will continue to provide development and regulatory guidance for the program.

This Phase 3 collaboration agreement will continue in force until the approval of Andexanet alfa as a reversal agent for rivaroxaban by the FDA and EMA.  Bayer and Janssen may terminate this agreement for convenience with 60 days’ advance written notice or for our bankruptcy or change of control.  In addition, either party may terminate this agreement for the other party’s uncured material breach or material safety issues or we can also terminate this agreement for failure of the Phase 3 studies.

In January 2016, we entered into collaboration agreements with Bayer to include rivaroxaban in the clinical studies for approval of Andexanet alfa in Japan. Under the terms of the agreement, we will receive an upfront payment of $5.0 million and are eligible to receive an additional milestone payment based on Japanese regulatory approval of Andexanet alfa as an antidote for rivaroxaban. Bayer will provide technical support as well as fund clinical studies of Andexanet alfa with rivaroxaban in Japan. Bayer received no commercial rights under this agreement.

Daiichi Sankyo agreement

In June 2013, we entered into an agreement with Daiichi Sankyo to include subjects dosed with edoxaban, their fXa inhibitor product, in one of our proof-of-concept studies of Andexanet alfa. We are responsible for the costs of conducting this clinical study. This agreement will continue in force until the later of the completion of the studies and the fulfillment of certain other conditions set forth in the agreement, unless earlier terminated by either party pursuant to the agreement. This agreement does not grant Daiichi Sankyo any other rights with respect to the development or commercialization of Andexanet alfa.

In July 2014, we entered into a second collaboration agreement with Daiichi Sankyo to further study the safety and efficacy of Andexanet alfa as a reversal agent to edoxaban through Phase 3 studies.  The second collaboration agreement covers the conduct of Phase 3 studies of Andexanet alfa with edoxaban and any potential U.S. and EU regulatory approval of Andexanet alfa as a reversal agent for edoxaban.  Under this Phase 3 collaboration agreement we received an upfront payment of $15.0 million and are eligible to receive additional development and regulatory milestone payments of up to $25.0 million.  These payments represent the total consideration under this agreement.  Daiichi Sankyo will continue to provide development and regulatory guidance for the program.

This Phase 3 collaboration agreement will continue in force until the approval of Andexanet alfa as a reversal agent for edoxaban by the FDA and EMA.  Daiichi Sankyo may terminate this agreement for convenience with 60 days’ advance written notice or for our bankruptcy or change of control.  In addition, either party may terminate this agreement for the other party’s uncured material breach or material safety issues, and we can also terminate this agreement for failure of the Phase 3 studies.

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Syk S elective Inhibitors

Biogen Idec agreement

In October 2011, we entered into an exclusive worldwide license and collaboration agreement with Biogen Idec to develop and commercialize PRT2607 and certain highly selective Syk inhibitors. Biogen Idec made an upfront cash payment to us of $36.0 million and purchased 636,042 shares of our Series 1 convertible preferred stock for an aggregate purchase price of $9.0 million. Pursuant to the agreement, we had an option to lead development and commercialization efforts in the United States for select smaller indications, as well as discovery efforts for follow-on Syk inhibitors and an option to co-promote the drug alongside Biogen Idec with major indications in the United States. In November 2012, we elected to exercise our option to convert the agreement to a fully out-licensed agreement. After such election, we relinquished our right to share profits from sales of products related to Syk inhibitors, but are entitled to receive tiered royalties at low-double-digit percentages (not greater than 20%) from sales of these products by Biogen Idec if product sales are ever achieved. We no longer have an obligation to fund the program under the agreement. The agreement also provides for additional payments to us of up to approximately $370 million based on the occurrence of certain development and regulatory events. Biogen Idec has elected to assume all future development work for Syk inhibitors, including the major indications, such as rheumatoid arthritis and allergic asthma. To date, no development or regulatory events provided by the agreement have occurred and no royalties have been triggered under our agreement with Biogen Idec. This agreement will continue in force until either party terminates the agreement pursuant to the agreement or until the expiration of Biogen Idec’s royalty obligations pursuant to the agreement, which is the later of the expiration of all relevant patents and regulatory exclusivities or 10 years after first commercial sale. Biogen Idec may terminate the agreement without cause upon 120 days’ written notice or for cause if Portola commits a material breach of its obligations under the agreement and fails to cure the breach. We may terminate the agreement with proper written notice for cause if Biogen Idec commits a material breach of its obligations under the agreement and fails to cure the breach for 90 days (or 60 days for nonpayment of an amount due) after written notice is given, if Biogen Idec commences a legal action challenging the validity, enforceability or scope of any of the patents subject to the agreement or in the event of bankruptcy, reorganization, liquidation or receivership of Biogen Idec. In such event, we would regain all development rights and Biogen Idec would have no further payment obligations pursuant to the agreement. In May 2015, the Biogen Idec agreement was terminated in its entirety.

Astellas agreement

In June 2005, we entered into an agreement to license certain exclusive rights to research, develop and commercialize Syk inhibitors from Astellas Pharma, Inc., or Astellas, which agreement was subsequently amended and restated in December 2010. The agreement with Astellas, as amended, requires us to make certain milestone, royalty and sublicense revenue sharing payments to Astellas as we develop, commercialize or sublicense Syk inhibitors. Pursuant to our agreement with Astellas, we made cash milestone payments to Astellas of $500,000 in May 2005, $500,000 in May 2006 and $1.0 million in December 2008, as we elected to continue our development of Syk inhibitors. In addition, for each Syk inhibitor product, we may be required to make up to $71.5 million in additional milestone payments to Astellas if the product is approved for multiple distinct indications in the United States, Europe and Japan and the product attains certain sales levels. If we grant a sublicense to develop and commercialize Syk inhibitors, we are required to pay Astellas 20% of any payments (excluding royalties) received under the sublicense agreement. In 2011, in connection with our receipt of the upfront payment under our agreement with Biogen Idec, we made a cash payment to Astellas of $7.2 million. In addition, we are required to pay Astellas royalties at low single-digit percentages for worldwide sales for any Syk inhibitor product made by us or our sublicensees. This agreement will continue in force, on a product-by-product and country-by-country basis, until the expiration of relevant patents or ten years after the launch, whichever is later, or termination by either party pursuant to the agreement. The agreement may be terminated by us for convenience upon 60 days’ written notice to Astellas or immediately upon written notice if all major claims of all of the patents covered by the agreement are invalidated by competent judicial or administrative authorities in the U.S. and no measure has been taken to appeal the invalidation. Either party may terminate the agreement upon written notice if the other party is in material breach of its obligations under the agreement for reasons within its control and responsibility and has not remedied the breach within 30 days of receiving written notice or in the event of bankruptcy, liquidation or receivership of the other party.

Cerdulatinib

Aciex agreement (Nicox)

In February 2013, we entered into a license and collaboration agreement with Aciex Therapeutics, Inc., or Aciex, pursuant to which we granted Aciex an exclusive license to co-develop and co-commercialize Cerdulatinib and certain related compounds for nonsystemic indications, such as the treatment and prevention of ophthalmological diseases by topical administration and allergic rhinitis by intranasal administration. In April 2014, this agreement was amended to release all rights for Cerdulatinib to us. The collaboration is now focused on development of other related compounds for topical ophthalmic indications. Under the agreement, we will share development costs with Aciex and be entitled to receive either a share of the profits generated by any eventual products or royalty payments. We retain rights to other indications, including dermatologic disorders.

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Ora agreement

In May 2015, we entered into a license and collaboration agreement with Ora pursuant to which we granted Ora an exclusive license to co-develop and co-commercialize one of our specific Syk inhibitors, PRT02761. Ora has the primary responsibility for conducting the research and development and regulatory activities under this agreement. We are obligated to provide assistance in accordance with the agreed-upon development plan, as well as participate on various committees.

Under the terms of this risk and cost sharing agreement, each party will incur its own share of development costs. Third-party related development costs will be shared by Ora and us at approximately 60% and 40%, respectively, until an End of Phase 2 meeting with the FDA, and equally thereafter. We are entitled to receive either 50% of the profits, if any, generated by future sales of the products developed under the agreement or royalty payments on such sales, should we opt out of the agreement.

We may opt out of the agreement any time prior to 90 days after an End of Phase 2 meeting with the FDA. The timing of the exercise of our opt out rights would impact future royalties we would be entitled to receive from Ora. Each party may also buy out the rights and interests in the licensed compound by paying the greater of $6.0 million or two times the actual aggregate development cost incurred by both parties on or before the date that is 90 days after an End of Phase 2 meeting with the FDA.

Manufacturing and clinical research agreements

CMC Biologics manufacturing agreement

In July 2014, we entered into an agreement with CMC ICOS Biologics, Inc., or CMC Biologics, a subsidiary of CMC Biologics S.à.r.l., a privately-held contract manufacturing organization, pursuant to which CMC Biologics will manufacture clinical and commercial supply of Andexanet alfa and perform pre-validation and validation work on our behalf. Andexanet alfa used in our clinical studies is currently produced for us by CMC Biologics, who will also support our initial BLA submission and initial commercial launch in the U.S.

Under the agreement, we are required to purchase an aggregate fixed number of batches of Andexanet alfa from CMC Biologics beginning in 2015 through 2021. Total batch commitments under the agreement can be increased or decreased based on the achievement of milestones relating to the regulatory approval process for Andexanet alfa, expansion of existing manufacturing capacity and operational qualification of CMC Biologics’ manufacturing facilities. We made an upfront payment to CMC Biologics in the amount of $10.0 million in July 2014 and made a reservation payment to CMC Biologics of $4.6 million in November 2014. Both payments will be credited against our future purchases of batches under the agreement.

Total fixed commitments under the agreement for the purchases of clinical and commercial batches, not taking into account possible price and batch adjustments per the terms of the agreement, are approximately $276.1 million. CMC Biologics also conducts pre-validation and validation work pursuant to work orders under the arrangement.

The term of the agreement is seven years and may be early terminated by either party for the other party’s uncured material breach or insolvency. We may also terminate the agreement if CMC Biologics is unable to add additional manufacturing capacity on a timely basis, if certain manufacturing-related regulatory events do not occur before certain deadlines, or if the batch yield is below a certain threshold, in which case we are not obligated to pay CMC Biologics a termination payment and CMC Biologics will be obligated to refund the uncredited amounts of the upfront payment and reservation payment. In addition, we may terminate the agreement unilaterally if we discontinue the development and commercialization of Andexanet alfa for regulatory, safety, efficacy or other commercial reasons, or if the projected market demand or gross margin of Andexanet alfa is below a minimum threshold. A termination agreement under these provisions will obligate us to pay CMC Biologics a termination fee between $5.0 million and $30.0 million, depending on the date of termination. The termination fee is highest from 2015 through 2017, and then decreases through 2021. Any remaining upfront payments or reservation payments we have made, not yet credited against the purchase of batches, at the time of termination will be applied against the termination fee.

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Lonza manufacturing agreement

We do not anticipate that supply from CMC Biologics, even as expanded, will be sufficient to meet projected worldwide demand for Andexanet alfa, therefore, we are developing an improved and more cost-effective process at Lonza Group Ltd, or Lonza. In June 2013, we signed an agreement with Lonza to develop a commercial-scale manufacturing process for Andexanet alfa. However, the first commercial material from Lonza will not become available until after our expected U.S. launch. In 2014 we completed our first 10,000 liter scale engineering batch with Lonza. The run successfully produced bulk drug substance that met our specifications and it appeared highly comparable to previously manufactured material. However, the yield was lower than we expected and we determined that the timeline needed to improve product yield at Lonza would result in a significant delay to our BLA submission on our intended timeline. As a result, our BLA submission used material from our ongoing CMC Biologics manufacturing process at an expanded production facility being constructed at CMC Biologics. Our broader worldwide commercial supply of Andexanet alfa is still expected to be manufactured by Lonza using what we anticipate will be an improved and more cost-effective process, with the first commercial material from Lonza becoming available following our U.S. launch.

In October 2014, we entered into a new commercial manufacturing agreement with Lonza, replacing the 2013 agreement, to produce commercial quantities of Andexanet alfa using the improved and more-cost-effective process and perform pre-validation and validation work on our behalf following our U.S. launch.

Under this new agreement, we are required to purchase at least seven commercial batches of Andexanet alfa per year from Lonza, over a period of five years following first regulatory approval of the product from Lonza’s facility. We may cancel these orders upon written notice to Lonza, in which case, we will be obligated to pay a cancellation fee ranging from between €10.0 million (or $10.9 million based on the exchange rate as of December 31, 2015) and €13.3 million (or $14.5 million based on the exchange rate as of December 31, 2015), depending on the time of cancellation and any applicable costs related to raw materials and certain pass-through costs.

The agreement will terminate on the fifth anniversary of the date of the first regulatory approval and may be early terminated by either party for the other party’s uncured material breach or insolvency or, prior to the first regulatory approval for any reason on not less than twelve months prior written notice. In addition, we may also terminate the agreement if we discontinue the development or commercialization of Andexanet alfa for regulatory, safety, efficacy or other commercial reasons and for technical reasons after delivery of the first engineering batch but before delivery of the second engineering batch. In such circumstance we will be obligated to pay a termination payment ranging from between €10.0 million (or $10.9 million based on the exchange rate as of December 31, 2015) and €15.0 million (or $16.4 million based on the exchange rate as of December 31, 2015), depending on the time of termination, which includes the cancellation fee, and any applicable costs related to raw materials.

Hovione manufacturing agreement

In January 2007, we entered into a development and manufacturing service agreement with Hovione Inter Limited, or Hovione, as amended on February 1, 2013, pursuant to which Hovione is producing the active pharmaceutical ingredient, or API, for Betrixaban for use in our APEX study. Under the agreement, Hovione produces the API using our proprietary process and to our specified quality standards and in compliance with applicable regulations. Hovione produces the API pursuant to work orders submitted by us and agreed to by Hovione, though Hovione is not under any obligation to enter into any work order.  The agreement remains in effect until the later of seven years after its effective date or the completion of any outstanding work orders. The agreement may be extended continuously for additional two-year periods upon agreement of the parties. We may terminate the agreement for convenience with 60 days’ written notice and either party may terminate the agreement with 60 days’ written notice upon the bankruptcy of the other party, the failure of the other party to cure a material breach of the agreement within 30 days of receiving notice of such breach, the occurrence of events that prevents the other party from performing its obligations or if either party determines that the agreement is detrimental to its interests and can demonstrate that it would be in the best interests of both parties to terminate the agreement.

PPD development agreement

In January 2012, we entered into a master contract services agreement with PPD Development, LP, or PPD, under which PPD provides administrative, data management and statistical analysis services relating to our APEX study. Pursuant to this agreement as amended, PPD is responsible for overseeing and managing the conduct of the APEX study in Latin America. We will remain ultimately responsible for the study and have separate agreements with the sites performing the study, other clinical research organizations and other third party vendors. This agreement will remain in effect until the later of three years after its effective date or the completion of services by PPD. Portola may terminate the agreement with 30 days’ notice or immediately upon a material breach of the agreement by PPD that cannot be cured. PPD may terminate the agreement immediately upon a material breach of the agreement by us that cannot be cured or, 30 days after giving notice of a curable material breach of the agreement by us, if we have not cured such breach.

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Competition

Our industry is highly competitive and subject to rapid and significant technological change. While we believe that our development experience and scientific knowledge provide us with competitive advantages, we may face competition from large pharmaceutical and biotechnology companies, smaller pharmaceutical and biotechnology companies, specialty pharmaceutical companies, generic drug companies, academic institutions, government agencies and research institutions and others.

Many of our competitors may have significantly greater financial, technical and human resources than we have. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors. Our commercial opportunity could be reduced or eliminated if our competitors develop or market products or other novel technologies that are more effective, safer or less costly than any that will be commercialized by us, or obtain regulatory approval for their products more rapidly than we may obtain approval for ours. Our success will be based in part on our ability to identify, develop and manage a portfolio of drugs that are safer, more efficacious and/or more cost-effective than alternative therapies.

Betrixaban

In the market for VTE prophylaxis in acute medically ill patients, Betrixaban, if approved, will compete with enoxaparin, which is marketed as Lovenox by Sanofi-Aventis U.S. LLC and as a generic pharmaceutical by several manufacturers, and to a lesser extent with other low molecular weight heparins. In addition, Betrixaban may face competition in the market for acute medically ill patients from other fXa inhibitors including apixaban, which is marketed by BMS and Pfizer, edoxaban, which is marketed by Daiichi Sankyo, rivaroxaban, which is marketed by Bayer and Janssen, and the direct thrombin inhibitor dabigatran, which is marketed by Boehringer Ingelheim GbmH, although none of these molecules is currently approved for use in that population. We believe, that in light of the significant opportunity in this acute medically ill population, other agents will likely be tested in a Phase 3 study. For example, in 2014, Janssen initiated a Phase 3 study designed to evaluate the efficacy and safety of rivaroxaban compared with placebo in the prevention of symptomatic VTE events and VTE-related death post-hospital discharge in high-risk, medically ill patients. Janssen also announced in 2014 that it had initiated a Phase 3 study designed to evaluate the efficacy and safety of rivaroxaban to reduce the risk of deep vein thrombosis, or DVT, and pulmonary embolism, or PE, due to a concurrent medical illness for up to 45 days after hospital discharge. As the dosing regimen for an anticoagulant typically varies based on the indication in which it is used and anticoagulants often work in one indication but not another, we and our clinical advisors think it is unlikely that a significant number of physicians will choose to prescribe a fXa inhibitor in the acute medically ill patient population absent a relevant regulatory approval or clinical evidence supporting its use. In the future, owners of approved direct fXa or thrombin inhibitors may decide to develop them for VTE prophylaxis in the acute medically ill patient population although nothing is in development for that indication to our knowledge. In addition, they or other competitors may decide to develop new therapies for VTE prophylaxis in acute medically ill patients.

Andexanet alfa

Currently there are no therapies approved as antidotes for fXa inhibitors. However, Andexanet alfa, if approved, may compete with currently approved treatments designed to enhance coagulation including fresh frozen plasma, prothrombin complex concentrates, rFVIIa, Vitamin K, protamine or whole blood. In addition, several companies have conducted clinical research on compounds that are intended to reverse the effects of one or more direct fXa inhibitors and which, if developed, may be competitive with Andexanet alfa. One of these companies, Perosphere Inc., is in Phase 2 clinical development of its compound.

Cerdulatinib

In the market for the treatment of CLL and NHL, Cerdulatinib, if approved, will compete with existing therapies, such as rituximab, and obinutuzumab which are marketed by Chugai Pharmaceutical Co., F. Hoffmann-LaRoche Ltd. and Genentech, Inc., ibrutinib, which is marketed by Janssen and Pharmacyclics, Inc. idelalisib, which is marketed by Gilead; and potentially other therapies currently in development by a number of different companies.

Syk Selective Inhibitors

In the market for treatment of allergic conjunctivitis, PRT2761, if approved, will compete with existing products, such as topical antihistamines, corticosteroids, and mast cell stabilizers and potentially with other products currently in development by a number of different companies.

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Intellectual property

Our success will significantly depend upon our ability to obtain and maintain patent and other intellectual property and proprietary protection for our drug candidates, including composition-of-matter, dosage and formulation patents, as well as patent and other intellectual property and proprietary protection for our novel biological discoveries and other important technology inventions and know-how. In addition to patents, we rely upon unpatented trade secrets, know-how, and continuing technological innovation to develop and maintain our competitive position. We protect our proprietary information, in part, using confidentiality agreements with our commercial partners, collaborators, employees and consultants and invention assignment agreements with our employees. We also have confidentiality agreements or invention assignment agreements with our commercial partners and selected consultants. Despite these measures, any of our intellectual property and proprietary rights could be challenged, invalidated, circumvented, infringed or misappropriated, or such intellectual property and proprietary rights may not be sufficient to permit us to take advantage of current market trends or otherwise to provide competitive advantages. For more information, please see “Risk factors—Risks related to intellectual property.”

As of December 31, 2015, we owned 41 issued U.S. patents, 31 U.S. patent applications and 158 issued patents and 180 patent applications in other jurisdictions. We also co-owned 10 additional patents and patent applications. In addition, as of December 31, 2015, we have licensed 198 issued patents and 32 patent applications from third parties, mostly on an exclusive basis. The patent portfolios for our leading product candidates as of December 31, 2015 are summarized below:

Betrixaban

Our Betrixaban patent portfolio includes 22 issued U.S. patents and 4 U.S. patent applications covering the composition of and methods of making and using Betrixaban or its analogs, including those owned by us and those licensed from Millennium. The U.S. issued patents relating to the composition of matter of Betrixaban are not due to expire before September 2020 and may be extended up to September 2025, if Betrixaban receives regulatory approval and if the necessary eligibility requirements are met, pursuant to the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Act. Betrixaban may also be eligible for an additional six months of pediatric exclusivity under the Best Pharmaceuticals for Children Act as described below. Related international patent applications have issued or been allowed in 35 countries and are pending in Europe and a number of other countries. These international patents and patent applications, if issued, would not be due to expire before September 2020.

In the United States, the Hatch-Waxman Act permits a patent term extension of up to five years for one patent related to an approved therapy. The length of the extension is based upon the period of time the therapy has been under regulatory review. We believe that, if Betrixaban is approved, we will be eligible for a full five year patent term extension for one patent relating to Betrixaban.

In addition, in the United States, the Best Pharmaceuticals for Children Act provides that the period of patent exclusivity for a drug may be extended for six months if the owner of the drug conducts studies of the drug in children pursuant to a request from the FDA. We believe that there may be pediatric applications for Betrixaban and, therefore, that it may be possible for us to obtain an additional six months of pediatric exclusivity of Betrixaban by conducting FDA-requested studies in children.

Andexanet alfa

Our fXa inhibitor antidote patent portfolio is wholly owned by us and includes nine issued U.S. patents and 13 U.S. patent applications covering the composition of and methods of making and using Andexanet alfa or its analogs. We retain full commercialization rights to Andexanet alfa on a worldwide basis except for Japan where commercial rights have been licensed to BMS and Pfizer.

The U.S. issued patents are not due to expire before June 2030. A related international patent application has issued in Australia, New Zealand, China, Japan, Mexico, and Singapore, another related international patent application has issued in China, Japan, New Zealand, Mexico and Singapore and international patent applications are pending in Europe and a number of other countries. These international patents and patent applications, if issued, would not be due to expire before September 2028.

Cerdulatinib

Our dual Syk-JAK inhibitor patent portfolio is owned in part by us and licensed in part from Astellas and includes five issued U.S. patents covering the composition of and methods of making and using Cerdulatinib or its analogs. The last to expire of the U.S. patents is not expected to expire before July 2029. Related international patent applications have issued or been allowed in 16 countries and are pending in Europe and a number of other countries. These international patents and patent applications, if issued, would not be due to expire before April 2029.

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Syk Selective Inhibitors

Our Syk-specific inhibitor patent portfolio is owned by us and includes four issued U.S. patents covering the composition of and methods of making and using PRT2607 or its analogs. The last to expire of the U.S. patents is currently expected to expire in July 2029. Related international patent applications have issued or been allowed in 26 countries and, have been granted in Europe and are pending in a number of other countries. These international patents and patent applications, if issued, would not be due to expire before April 2029.

Manufacturing

We rely on contract manufacturing organizations, or CMOs, to produce our drug candidates in accordance with the FDA’s and EMA’s current Good Manufacturing Practices, or cGMP, regulations for use in our clinical studies. The manufacture of pharmaceuticals is subject to extensive cGMP regulations, which impose various procedural and documentation requirements and govern all areas of record keeping, production processes and controls, personnel and quality control. Our small molecule drug candidates, Betrixaban and Cerdulatinib, are manufactured using common chemical engineering and synthetic processes from readily available raw materials. We rely on Hovione to produce API for Betrixaban for our APEX study. Pursuant to a development and manufacturing service agreement between us and Hovione, Hovione produces the API for Betrixaban using our proprietary process and to our specified quality standards and in compliance with applicable regulations. Hovione produces the API pursuant to work orders submitted by us and agreed to by Hovione, though Hovione is not under any obligation to enter into any work order and may terminate the agreement under certain conditions. Andexanet alfa is a recombinant biologic molecule produced in living cells, a process that is inherently complex and requires specialized knowledge and extensive process optimization and product characterization to transform laboratory scale processes into reproducible commercial manufacturing processes.

Our current Phase 4 ANNEXA study is using clinical material with bulk drug substance manufactured by CMC Biologics. We are currently continuing and expanding our ongoing work with CMC Biologics from clinical supply to commercial supply for our potential U.S. launch. Under our commercial supply agreement, CMC Biologics plans to increase production capacity at a lower cost than that of our current clinical supply for Andexanet alfa. We are also working with Lonza Group Ltd., or Lonza, to develop a large-scale commercial manufacturing process. Under our manufacturing supply agreement with Lonza, we plan to further increase our production capacity and to enhance our manufacturing process at Lonza to provide broader worldwide supply following our potential U.S. launch.

We currently have no plans to build our own clinical or commercial scale manufacturing capabilities. To meet our projected needs for clinical supplies to support our activities through regulatory approval and commercial manufacturing, the CMOs with whom we currently work will need to increase scale of production or we will need to secure alternate suppliers. We believe that there are multiple potential sources for our contract manufacturing, but we have not engaged alternate suppliers in the event that our current CMOs are unable to scale production. Our relationships with CMOs are managed by internal personnel with extensive experience in pharmaceutical development and manufacturing.

If we are unable to obtain sufficient quantities of drug candidates or receive raw materials in a timely manner, we could be required to delay our ongoing clinical studies and seek alternative manufacturers, which would be costly and time-consuming.

Government regulation

The FDA and comparable regulatory agencies in state and local jurisdictions and in foreign countries impose substantial requirements upon the clinical development, manufacture and marketing of pharmaceutical products. These agencies and other federal, state and local entities regulate research and development activities and the testing, manufacture, quality control, safety, effectiveness, labeling, storage, record keeping, approval, advertising and promotion of our products.

The process required by the FDA before product candidates may be marketed in the United States generally involves the following:

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The testing and approval process requires substantial time, effort and financial resources. Prior to commencing the first clinical trial with a product candidate, we must submit an IND to the FDA. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day time period, raises concerns about the supporting safety data or questions about the design of the clinical trial and imposes a clinical hold. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. Submission of an IND may not result in FDA authorization to commence a clinical trial. A separate submission to the existing IND must be made for each successive clinical trial conducted during product development. Further, an independent institutional review board for each medical center proposing to conduct the clinical trial must review and approve the plan for any clinical trial and its informed consent form before the clinical trial commences at that center. Regulatory authorities or an institutional review board or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the subjects or patients are being exposed to an unacceptable health risk. Some studies also include an Independent Data Monitoring Committee, or IDMC, which receives special access to unblinded data during the clinical trial and may halt the clinical trial if it determines that there is an unacceptable safety risk for subjects or other grounds, such as no demonstration of efficacy. The IDMC may halt a trial if it feels that the data demonstrate efficacy of the drug and it is no longer ethical to withhold the drug from patients in the control arm of the study.

For purposes of NDA or BLA approval, human clinical trials are typically conducted in three sequential phases that may overlap.

Concurrent with clinical trials, companies usually complete additional animal studies and must also develop additional information about the chemistry and physical characteristics of the product candidate as well as finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, the sponsor must also develop methods for testing the identity, strength, quality and purity of the final product. Additionally, appropriate packaging must be selected and tested and stability studies must be conducted to establish an appropriate shelf life for the product candidate including data demonstrating that the product candidate does not undergo unacceptable deterioration over its shelf life.

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NDA or BLA submission and review by the FDA

The results of product development, nonclinical studies and clinical trials are submitted to the FDA as part of an NDA or BLA. The submission of an NDA or BLA requires payment of a substantial User Fee to FDA. The FDA may convene an advisory committee to provide independent expert clinical opinion on application review questions. The FDA reviews applications to determine, among other things, whether a product is safe and effective for its intended use and whether the manufacturing controls are adequate to assure consistent batch to batch purity, identity, potency, and strength of the product candidate. Before approving an NDA or BLA, the FDA will inspect the facility or facilities where the product is manufactured. The FDA has informed us that our BLA for Andexanet alfa may also be subject to prior review by an advisory committee. The FDA will not approve an application unless it determines that the manufacturing processes, equipment and facilities are in compliance with cGMP requirements. Once the NDA submission has been accepted for filing (sixty days post receipt of the application by the FDA), the FDA typically takes ten months to review the application and respond to the applicant, which can take the form of either a Complete Response Letter or Approval. The review process is often significantly extended by FDA requests for additional information or clarification. The FDA may delay or refuse approval of an NDA if applicable regulatory criteria are not satisfied, require additional testing or information and/or require post-marketing testing and surveillance to monitor safety or efficacy of a product. FDA approval of any NDA or BLA submitted by us will be at a time the FDA chooses. Also, if regulatory approval of a product is granted, such approval may entail limitations on the indicated uses for which such product may be marketed and require post-marketing requirements such as a Risk Evaluation and Mitigation Procedure or a Phase 4 study. Once approved, the FDA may withdraw the product approval if compliance with pre- and post-marketing regulatory standards is not maintained or if problems occur after the product reaches the marketplace. In addition, the FDA may require Phase 4 post-marketing studies to monitor the effect of approved products, and may limit further marketing of the product based on the results of these post-marketing studies.

The FDA has a fast track program that is intended to expedite or facilitate the process for reviewing new drugs and biological products that meet certain criteria. Specifically, new drugs and biological products are eligible for fast track designation if they are intended to treat a serious or life-threatening condition and demonstrate the potential to address unmet medical needs for the condition. Fast track designation applies to the combination of the product and the specific indication for which it is being studied. For a fast track product, the FDA may consider review of completed sections of an NDA or BLA on a rolling basis provided the sponsor provides, and the FDA accepts, a schedule for the submission of the completed sections of the NDA or BLA. Under these circumstances, the sponsor pays any required user fees upon submission of the first section of the NDA or BLA. A fast track designated drug candidate may also qualify for priority review, under which the FDA reviews the NDA or BLA in a total of six months rather than ten months after it is accepted for filing.

Post-approval requirements

Any products manufactured or distributed by us pursuant to FDA approvals are subject to continuing regulation by the FDA, including record-keeping requirements and reporting of adverse experiences. Drug and biologic manufacturers and their subcontractors are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with GMP, which impose certain procedural and documentation requirements upon us and our third-party manufacturers. We cannot be certain that we or our present or future suppliers will be able to comply with the GMP regulations and other FDA regulatory requirements. If our present or future suppliers are not able to comply with these requirements, the FDA may halt our clinical trials, require us to recall a product from distribution, or withdraw approval of the NDA or BLA.

The FDA closely regulates the marketing and promotion of drugs. A company can make only those claims relating to safety and efficacy, purity and potency that are approved by the FDA. Failure to comply with these requirements can result in adverse publicity, warning letters, corrective advertising and potential civil and criminal penalties. Physicians may prescribe legally available products for uses that are not described in the product’s labeling and that differ from those tested by us and approved by the FDA. Such off-label uses are common across medical specialties. Physicians may believe that such off-label uses are the best treatment for many patients in varied circumstances. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, restrict manufacturer’s communications on the subject of off-label use.

Healthcare and reimbursement regulation

Our sales, promotion, medical education and other activities following product approval will be subject to regulation by numerous regulatory and law enforcement authorities in the United States in addition to FDA, including potentially the Federal Trade Commission, the Department of Justice, the Centers for Medicare and Medicaid Services, other divisions of the Department of Health and Human Services and state and local governments. Our promotional and scientific/educational programs must comply with the anti-kickback provisions of the Social Security Act, the Foreign Corrupt Practices Act, the False Claims Act, the Veterans Health Care Act and similar state laws.

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Depending on the circumstances, failure to meet these applicable regulatory requirements can result in criminal prosecution, fines or other penalties, injunctions, recall or seizure of products, total or partial suspension of production, denial or withdrawal of pre-marketing product approvals, private “qui tam” actions brought by individual whistleblowers in the name of the gov ernment or refusal to allow us to enter into supply contracts, including government contracts.

Sales of pharmaceutical products depend significantly on the availability of third-party reimbursement. Third-party payors include government health administrative authorities, managed care providers, private health insurers and other organizations. We anticipate third-party payors will provide reimbursement for our products. However, these third-party payors are increasingly challenging the price and examining the cost-effectiveness of medical products and services. In addition, significant uncertainty exists as to the reimbursement status of newly approved healthcare products. We may need to conduct expensive pharmacological studies to demonstrate the cost-effectiveness of our products. The product candidates that we develop may not be considered cost-effective. It is time consuming and expensive for us to seek reimbursement from third-party payors. Reimbursement may not be available or sufficient to allow us to sell our products on a competitive and profitable basis.

The United States and some foreign jurisdictions are considering or have enacted a number of legislative and regulatory proposals to change the healthcare system in ways that could affect our ability to sell our products profitably. Among policy makers and payors in the United States and elsewhere, there is significant interest in promoting changes in healthcare systems with the stated goals of containing healthcare costs, improving quality and/or expanding access. In the United States, the pharmaceutical industry has been a particular focus of these efforts and has been significantly affected by major legislative initiatives.

Foreign regulation

In addition to regulations in the United States, we will be subject to a variety of foreign regulations governing clinical trials and commercial sales and distribution of our products to the extent we choose to develop or sell any products outside of the United States. The approval process varies from country to country and the time may be longer or shorter than that required to obtain FDA approval. The requirements governing the conduct of clinical trials, product licensing, pricing and reimbursement vary greatly from country to country.

EU member states require both regulatory clearances by the national competent authority and a favorable ethics committee opinion prior to the commencement of a clinical trial. Under the EU regulatory systems, we may submit marketing authorization applications either under a centralized or decentralized procedure. The centralized procedure provides for the grant of a single marketing authorization that is valid for all EU member states. The centralized procedure is compulsory for medicines produced by certain biotechnological processes, products with a new active substance indicated for the treatment of certain diseases, such as neurodegenerative disorder or diabetes and products designated as orphan medicinal products and optional for those products which are highly innovative or for which a centralized process is in the interest of patients. The decentralized procedure of approval provides for approval by one or more other, or concerned, member states of an assessment of an application performed by one member state, known as the reference member state. Under the decentralized approval procedure, an applicant submits an application, or dossier, and related materials (draft summary of product characteristics, draft labeling and package leaflet) to the reference member state and concerned member states. The reference member state prepares a draft assessment and drafts of the related materials within 120 days after receipt of a valid application. The sponsor responds to any inquiries and the final report is issued on the 120 ^th day from submission of application. The final report is forwarded to the EMA for review and approval. Within 90 days of receiving the reference member state’s assessment report, each concerned member state must decide whether to approve the assessment report and related materials. If a member state cannot approve the assessment report and related materials on the grounds of potential serious risk to public health, the disputed points may eventually be referred to the European Commission, whose decision is binding on all member states.

Employees

As of December 31, 2015, we had 137 full-time employees, 26 of whom hold Ph.D. degrees and 6 of whom hold M.D. degrees. Of the full-time employees, 91 employees are engaged in research and development and 46 are engaged in general administration, business development, sales and marketing. Our employees are not represented by labor unions or covered by collective bargaining agreements. We consider our relationship with our employees to be good.

Facilities

We lease approximately 74,000 square feet of research and office space in South San Francisco, California under a lease that expires in March 2020. Thereafter, at our option, we may extend the term for an additional three years through March 2023. We believe that our existing facilities are sufficient for our current needs for the foreseeable future.

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Legal proceedings

We are not currently a party to any material legal proceedings.

Corporate and Available Information

Our principal corporate offices are located at 270 E. Grand Avenue, South San Francisco, California 94080 and our telephone number is (650) 246-7000. We were incorporated in Delaware in September 2003. Our internet address is www.portola.com. We make available on our website, free of charge, our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and any amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, as soon as reasonably practicable after we electronically file such material with, or furnish it to, the Securities and Exchange Commission, or the SEC. Our SEC reports can be accessed through the Investors section of our internet website. Further, a copy of this Annual Report on Form 10-K is located at the SEC’s Public Reference Rooms at 100 F Street, N.E., Washington, D. C. 20549. Information on the operation of the Public Reference Room can be obtained by calling the SEC at 1-800-SEC-0330. The SEC maintains a website that contains reports, proxy and information statements and other information regarding our filings at http://www.sec.gov. The information found on our internet website is not incorporated by reference into this Annual Report on Form 10-K or any other report we file with or furnish to the SEC.