Company Background

We are a Delaware corporation, originally incorporated in 1988 under the name Terrapin Diagnostics, Inc. in the state of Delaware, and subsequently renamed “Telik, Inc.” in 1998, and MabVax Therapeutics Holdings, Inc. in September 2014. Our principal corporate office in the United States is at 11588 Sorrento Valley Road, Suite 20, San Diego, CA 92121 telephone: (858) 259-9405. Our internet address is www.mabvax.com. On July 8, 2014, we consummated a merger with MabVax Therapeutics, pursuant to which our subsidiary Tacoma Acquisition Corp. merged with and into MabVax Therapeutics, with MabVax Therapeutics surviving as our wholly owned subsidiary. This transaction is referred to as the Merger. Immediately following the Merger, the former holders of the issued and outstanding securities of MabVax Therapeutics held approximately 85% of our issued and outstanding securities.

On September 8, 2014, we filed an amended and restated certificate of incorporation to increase the authorized number of shares of our common stock to a new total of 150,000,000 shares, increase the number of shares of our preferred stock to a new total of 15,000,000 shares, and change our name from “Telik, Inc.” to “MabVax Therapeutics Holdings, Inc.”

Overview

We are a clinical-stage biopharmaceutical company focused on discovering and developing innovative vaccine and monoclonal (produced from a single DNA sequence encoded into multiple cells that all produce the same single antibody) antibody-based therapeutics for the diagnosis and treatment of cancer. We generate our pipeline of antibody-based product candidates from patients who have been vaccinated with propriety vaccines licensed from Memorial Sloan Kettering Cancer Center (“MSKCC”). Our approach of surveying the protective immune response from many patients to identify the ideal monoclonal antibody candidate against a specific target on the surface of a cancer cell is a novel next-generation human antibody technology platform. We believe our approach to antibody discovery identifies the antibody candidates with superior performance characteristics while minimizing many of the toxicity and off target binding drawbacks (phenomenon occurring when antibodies bind to non-cancer cells) of other discovery technologies. Our lead antibody candidates have been recovered from patients who had substantially better treatment outcomes than almost all other patients in clinical trials conducted by us and our partners.

Our therapeutic vaccines were developed at MSKCC and are exclusively licensed to us pursuant to agreements entered into in 2008. These vaccines are administered in the adjuvant (period following conventional treatment consisting of watchful waiting) setting and have shown in clinical studies to elicit a protective antibody response. The antibodies are intended to seek out circulating tumor cells and micrometastases (small clusters of cancer cells) to kill them before they can cause cancer recurrence. Our lead cancer vaccines targeting recurrent sarcoma (soft tissue cancer) and ovarian cancer are currently in proof of concept Phase II multi-center clinical trials. Both trials have received substantial federal grant monies to support their development. A vaccine to address the orphan disease neuroblastoma (cancer starting in the adrenal gland of children which may spread to nervous tissue and bone marrow) has completed an initial Phase I trial at MSKCC yielding encouraging results. This vaccine product candidate is expected be ready for a Phase II trial in 2015. We and MSKCC have completed additional Phase I vaccine clinical trials in melanoma, ovarian cancer, breast cancer, and small cell lung cancer over the last three years.

Market Opportunity and Competition

Antibodies as targeted therapeutic treatments for cancer have become a significant market accounting for more than $20 billion in revenue according to Global Data’s commercial database Pharma eTrack. Eight of the leading twenty therapeutic products for the treatment of cancer are antibodies according to Global Data’s commercial database Pharma eTrack. There are more than 150 monoclonal antibodies in development for cancer alone according to Global Data’s commercial database Pharma eTrack. The focus on the development of new monoclonal antibody based drugs is expected to continue for multiple reasons. Targeted therapies can attack cancer cells while minimizing damage to normal cells in the patient. Antibodies are complex molecules and are difficult and expensive to duplicate with biosimilars and therefore have a potentially longer commercial life. Currently monoclonal antibodies receive very favorable reimbursement levels from federal, state, and private insurance providers. This favorable treatment is expected to continue.

We have focused our initial antibody development efforts on matching the early antibody discoveries against diseases for which there remains a significant unmet medical need. Our lead antibody candidate targets an antigen over expressed on metastatic pancreatic, colon, breast, and small cell lung cancers. Patients who develop metastatic disease with these cancers have a significantly poorer prognosis. In the case of pancreatic and small cell lung cancer we believe that there are no treatments currently available that focus on metastatic disease. We are developing this lead antibody as a stand-alone therapeutic agent as well as

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combining it with a radiolabel for use as a novel PET imaging agent. According to the National Cancer Institute’s SEER database, there are approximately 100,000 patients annually who develop metastatic disease from these cancers who could potentially benefit from this antibody if it is successfully developed. This product has completed its preclinical development and GMP manufacturing has been initiated to produce Phase I clinical material by mid-2015. We expect to conduct a Phase I in the second half of 2015.

We have initiated development efforts on a second antibody that targets an antigen over expressed on the surface of sarcoma, melanoma, and neuroblastoma. The use of a targeted antibody therapy in neuroblastoma in a study sponsored by the National Cancer Institute and published in the New England Journal of Medicine has demonstrated that antibodies targeting this antigen can be effective. We are focused on developing an antibody-based drug for the treatment of sarcoma. While there are newer agents being developed to treat sarcoma, it is a difficult to treat cancer with unacceptably high recurrence rates. We believe that there are approximately 30,000 patients who could potentially benefit from this antibody if it is successfully developed. This product is in preclinical development and is expected to move to GMP manufacturing in late 2016.

Recent Developments

In the past year, full enrollment has been achieved in both the sarcoma and ovarian cancer vaccine Phase II clinical trials. We expect to analyze the endpoint of progression free survival, or PFS, and both clinical programs are following patients to the OS endpoint that is expected to be reached in 2016. Our discussions with the FDA at the time we developed the protocols for our vaccine trials indicated that the OS endpoint was the primary evaluation criteria for their evaluation of the efficacy and safety of the vaccines. The results of the Phase I trial with our neuroblastoma vaccine were published recently in Clinical Cancer Research. The study report describes an encouraging study result with a small cohort of difficult to treat patients who have repeatedly relapsed.

As noted in our Management’s Discussion and Analysis of Financial Results, our lead antibody candidate, 5B1, is being developed for the treatment of pancreatic and colon cancer.

Product Candidates

5B1 Antibody Program

Of the many tumor restricted monoclonal antibodies resulting from immunization of mice with human cancer cells, the majority have been directed against carbohydrate antigens (structures consistently expressed and are targets for therapeutic intervention) expressed at the cell surface. The carbohydrate antigen sialyl Lewis ^a  (sLe ^a ) is the antigen recognized by monoclonal antibody CA19.9 and it is widely expressed on tumors of the gastrointestinal tract. These tumor types are generally classified as epithelial tumors (a broad classification of tumor types) and include pancreatic, colon, stomach, ovarian, breast, and small cell lung cancers. A CA19.9 serum test is the only FDA validated marker for pancreatic cancer and is a commercial test that is readily available and used frequently to aid in the diagnosis of pancreatic cancer. Circulating epithelial cancer cells over-express sLea (abbreviation for the antigen sialyl Lewis A) and as a ligand (binding partner) for E selectin (a structure in the inner lining of blood vessels) this antigen facilitates tumor—tissue interactions that are key events for tumor metastasis. Patient outcomes appear to be worse in patients with metastatic tumors expressing higher levels of sLea according to articles published by T. Ben-David and colleagues in Immunology Letters in 2008 and YI Kawamura in Cancer Research in 2005. Because these tumor types express very high numbers of the sLea antigen on their cell surface, it makes the antigen an attractive target for therapeutic intervention.

We have created a series of fully human monoclonal antibodies against sLea. One antibody in particular, 5B1, has demonstrated exceptionally high affinity and specificity for sLea, and has very good efficacy in multiple tumor xenograft models (human cancer cells engrafted into mice) in studies conducted by MSKCC. 5B1 is a fully human full-length monoclonal antibody we discovered by capturing a portion of the immune response from seven stage IV breast cancer patients who were being vaccinated in a Phase I trial in 2008 at MSKCC with one of our licensed vaccines. Six of the original seven patients who participated in the trial are alive today and the patient from whom we recovered the 5B1 antibody is disease free five years post vaccination.

We have conducted tissue microarray work (normal and cancer tissue samples placed on slides treated with the antibody to determine if an antibody binds to such tissue samples) with commercially available tissue samples of both normal and cancer tissues. The results of this work indicated that the 5B1 antibody bound to multiple types of epithelial tumors, including pancreatic, colon, bladder, ovarian, breast, and small cell lung cancer tissues. The antibody did not bind to normal tissues except for the exocrine cells at the ductal border of secretory cells (primarily cells in the gastrointestinal tract that face into the digestive system and not inward to the body) in epithelial tissues; those sites are less accessible to the immune system. Both characteristics combined with the significant cytotoxicity demonstrated in  in vitro  testing led us to move to xenographic animal model testing. 5B1 has demonstrated in our pre-clinical studies good anti-tumor activity in a variety of animal models with multiple tumor types. Specifically, we have obtained positive results from animal models examining human pancreatic, colon, and small cell lung cancers.

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We have entered into a manufacturing agreement with Patheon (f.k.a. Gallus BioPharmaceuticals) to manufacture clinical supplies of the antibody, and plan to enter a Phase I clinical trial in 2015 to determine the safety and pharmacokinetics (assessment of the distribution and metabolism of a drug) of the 5B1antibody in patients of different cancer types. We expect that the clinical trial will help us determine if the antibody demonstrates anti-tumor activity over a range of doses tested. We expect the preliminary results of our Phase I studies to be initially available in 2015 with full Phase I results in 2016.

5B1 Imaging Program

Circulating biomarkers (substances released by certain cells that can be measured to assess if a patient has or is likely to have a particular type of cancer) such as CA19.9 are important clinical tools for early detection and diagnosis as well as monitoring of therapeutic progress, and detection of tumor recurrence in oncology. However, false positive readings due to biomarker production from benign disorders in unrelated host tissues are a significant problem. We believe that probing the site(s) of biomarker secretion with an imaging tool could be a broadly useful strategy to enhance the fidelity of diagnosis and staging of cancers such as pancreatic ductal adenocarcinoma, or PDAC, a notoriously occult (difficult to diagnose and treat) cancer. Moreover, such a tool could guide patient stratification for directed therapeutic intervention, surgical planning and aide in the evaluation of tumor response to chemotherapy and radiation therapy. To address this opportunity clinically, together with Dr. Jason Lewis’ radiochemistry laboratory at MSKCC, we developed  ⁸⁹ Zr-5B1, a fully human, antibody-based radiotracer (combined antibody and radiolabel) targeting tumor-associated CA19.9. In preclinical studies, ⁸⁹ Zr-5B1 localized to tumors in multiple models representing diseases with both undetectable and clinical relevant circulating CA19.9 serum levels. Among these,  ⁸⁹ Zr-5B1 detected tumor in an orthotopic model (xenograph model where human cancer cells are surgically implanted in the corresponding organ of the mouse) of PDAC, an elusive cancer for which the serum assay (actual test for a biomarker) is measured in a human, but with limited specificity in part because of the frequency of CA19.9 secretion from benign hepatic pathologies (certain non-cancer conditions such as inflammation causing the production of the target biomarkers resulting in a false reading). Of further note, in preliminary experiments  ⁸⁹ Zr-5B1 showed better tumor specificity (targeting only a specific type of cancer cell) compared to the commonly used 2-deoxy-2-( ¹⁸ F)-fluoro-D-glucose, or FDG, imaging agent, which relies on increased tumor metabolism relative to nonmalignant cells, and is known to lack sensitivity and specificity in pancreas cancers and other slow growing cancers.

To facilitate the development of the 5B1based antibody conjugated to a radiolabel as a novel PET imaging agent for pancreatic cancer, we applied for and received a development contract from NIH pursuant to which NIH may provide up to $1.75 million in non-dilutive funding for this project. We will be reach the clinic in 2015 with this novel product. We expect the preliminary results of our Phase I study to be initially available in 2015 with full Phase I results in 2016

5B1 Antibody Drug Conjugate

We observed in our clinical studies that certain types of cancer cells internalized the 5B1 antibody. These were primarily pancreatic cancer tumor types. We believe that this characteristic of the 5B1 antibody could be highly useful in constructing an antibody-drug conjugate. The development of antibody-drug conjugates is an area of intense competitive development with few companies capable of producing viable linker and toxin technologies that can be coupled with an antibody which, in this case, serves as the targeting mechanism. According to an analysis conducted utilizing the online database Global Data, over the last few years more than 21 technology access licensing deals worth more than $6 billion have been completed by biopharmaceutical companies to gain access to these technologies. We were able to identify and form an early collaboration with Heidelberg Pharm who has developed its own proprietary linker and toxin technology. For the collaboration, we were able to supply the 5B1 antibody and Heidelberg has conducted both in vitro and in vivo experiments demonstrating the significant potential utility of this combination. We are hoping to expand this collaboration and continue a joint development program to bring this new product to the clinic.

Follow-on Antibody Products From Our Discovery Library

1B7 and 31F9 Antibody Program

We have discovered multiple fully-human antibodies to the antigen GD2, which is significantly over expressed on sarcoma, melanoma, and neuroblastoma. These are three related cancers classified as neuroectodermal cancers (sarcoma, melanoma, neuroblastoma). We discovered these antibodies by examining the immune response from more than 60 patients who participated in our sarcoma vaccine trial over the last three years. According to an article published in the New England Journal of Medicine by Yu and colleagues in 2010, antibodies against GD2 have already been validated as effective therapeutic agents in a well-controlled Phase III clinical trial that produced statistically significant improvement in time to progression of disease in children suffering

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from neuroblastoma. Each of the two potential development candidates have specificity and affinity for the GD2 target and demonstrate significant ability to kill cancer cells that express GD2. Each antibody has a unique set of characteristics and, as part of the preclinical evaluation program, researchers at MSKCC will provide further  in vitro  and  in vivo  testing in multiple models of disease to help us decide which candidate to move forward toward clinical testing. We are currently targeting sarcoma as the primary indication for which we plan to develop an anti-GD2 antibody product.

Antibody Discovery

We have discovered and recombinantly expressed more than 100 fully human antibodies to eleven separate targets over expressed on multiple types of cancer. The antigenic targets are incorporated in various combinations making up the eight vaccines that were licensed from MSKCC and have been in at least Phase I clinical trials. To date, six separate vaccines have entered early stage clinical programs and we have received antibody discovery material from all patients who participated in five of the trials. Exclusive access to these patient samples is covered under separate licenses with MSKCC. We have discovered multiple antibodies to important cancer targets such as MUC1, GD3, GM2, Fucosyl-GM1, Globo-H, Tn, sTn, and TF. As we continue to raise additional capital and add capacity, it is our intention to begin moving these early product development candidates forward toward clinical evaluation.

Current Approach to Treatment of Pancreatic Cancer

According to an article in the Journal of Advanced Practitioner in Oncology , or Advanced Practitioner , by Sheena Daniels, DNP, ARNP, FNP-BC and colleagues in 2011, for the more than 80% of patients diagnosed with pancreatic cancer who will not be candidates for resection and a large number (80%) of patients who were able to have resection but will develop metastases within 2 to 3 years, the drug gemcitabine has been established as the standard of care because of its documented advantage in OS and more favorable side-effect profile. In patients who are not resectable (able to remove through surgery), combination therapy with a gemcitabine-based systemic regimen followed by consolidation with chemoradiation has produced some favorable median survival durations.

Newer Therapeutic Agents

According to Daniels’ article in the Advanced Practitioner , in spite of aggressive treatment, patients with unresectable pancreateic cancer have a median survival of 10 to 14 months and an estimated 1 in 4 patients who undergo pancreatic resection do not recover sufficiently from surgery to allow administration of systemic chemotherapy. Newer targeted agents have been studied in combination with gemcitabine but did not correlate with improved OS. However, according to Daniel, the combination of gemcitabine and erlotinib did improve overall survival from 5.91 months to 6.24 months and 1-year survival improved to 23% vs 17%. These results were not duplicated using multi-targeted kinase inhibitors. There are several ongoing trials combining additional chemotherapeutic agents with gemcitabine and early results show improvements in PFS and OS but come at a significant cost of increased adverse events. Nab-paclitaxel combined with gemcitabine has produced positive results in an early Phase II trial and those results were confirmed in a subsequent Phase III trial. Nab-paclitaxel is now approved for treatment of pancreatic cancer and the combination of gemcitabine and Nab-paclitaxel is considered first line therapy in many institutions.

We believe there is a significant unmet medical need for newer agents that can treat metastatic disease. Pancreatic cancer is an area of intense research with much of the late stage clinical development efforts targeted toward advanced and metastatic disease. According to the online database BCIQ from BioCentury, to date there are 92 products in all three stages of clinical development from a total of 86 companies and there are 14 products in Phase III or pivotal trials at this time.

Potential Market Opportunity for the Full Length Therapeutic Antibody 5B1

There is a critical unmet medical need for new and better treatment for metastatic pancreatic and colon cancer. According to the National Cancer Institutes SEER database, the five-year survival rate for patients with metastatic pancreatic cancer is just 1.8%. There are 43,000 new pancreatic cancer patients per year and more than half of them present at initial diagnosis with metastatic disease. According to the SEER database, the five-year survival rate for patients with metastatic colon cancer is only slightly better at 12%. According to the SEER database, while most of the 141,000 new patients can be treated successfully initially, almost half of all colon cancer patients will develop metastatic disease. Thus, adding the number of metastatic disease patients for these two cancers alone represent 96,000 new metastatic cancer patients per year. Using the cost of current antibody therapies as a baseline, the market potential for an annual patient population of 96,000 is in excess of $1 billion per year.

Pancreatic Cancer Imaging and Diagnosis

We believe that the radiolabeled 5B1 antibody represents the only human derived agent in development specifically aimed at improving imaging in pancreatic cancer. Since the antigen targeted by the 5B1 antibody is significantly and preferentially over

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expressed on metastatic pancreatic cancer, this development effort represents a potentially important step forward in the diagnosis, staging, and assessment of the majority of pancreatic cancer patients. We believe that the market opportunity for a 5B1antibody-based radiopharmaceutical is significant in multiple ways. The ability of physicians to accurately diagnose, stage, and assess treatment outcomes in pancreatic cancer would be very important. Accurate determinations on the extent of disease and resectability are essential to improve outcomes in this cancer. Potentially almost all patients diagnosed with pancreatic cancer could benefit from  ⁸⁹ Zr-hu5B1 scan. Accordingly, improvements in the sensitivity and specificity of one of the primary diagnostic tools could have a significant impact on clinical outcome.

Currently, according to Daniels’ article in the Advanced Practitioner , all screening methods for pancreatic cancer have limitations. The symptoms associated with the disease are often vague and attributed to other more benign etiologies. Diagnosing pancreatic cancer is often challenging, as the presenting symptoms of pancreatic, hepatobiliary (portion of the liver, pancreas, and biliary tract), and upper gastrointestinal cancers are similar. Screening for pancreatic cancer, according to Daniel, is difficult primarily because there are no tumor markers that can be screened at an early stage of disease. Therefore, according to Daniel, the majority of pancreatic cancers are diagnosed at a late stage of disease hampering efforts to provide curative therapy. Pancreatic cancer is typically diagnosed by a combination of history and physical examination, coupled with CT, ultrasound, and PET imaging. In patients deemed to be at high risk for metastasis or for whom the staging is indeterminate, the diagnosis is confirmed by fine needle aspiration or laparoscopy along with FDG-PET. Accurate staging, particularly identification of distant metastases, is of paramount importance in order to properly select patients who are the most likely to benefit from surgery. Differential diagnosis between pancreatic cancer and pancreatitis (non-cancerous inflammation of the liver) is a common problem with imaging modalities.

Recent Developments in ImmunoPET Imaging

2-deoxy-2-( ¹⁸ F)-fluoro-D-glucose, or FDG, combined with PET imaging alone, or FDG-PET, combined with CT scanning, or FDG-PET/CT, is commonly used to augment the diagnosis and staging of pancreatic cancer. According to an article in The American Journal of Surgery by Lan and colleagues in 2012, FDG-PET is the principal imaging agent available today for enhanced PET imaging for pancreatic cancer. FDG is a radiolabeled form of glucose and because cancer cells normally have elevated metabolic rates, highly active cells will incorporate this glucose marker and as a result can potentially help pinpoint pancreatic cancer and potential metastases.

To date, there have been 17 studies examining the accuracy of FDG-PET and the conclusions are mixed. While studies are heterogeneous (not of a similar type; not uniform), the utility of FDG-PET was reasonably established for the primary diagnosis purposes only, utility of FDG-PET/CT for determining recurrence and staging was not confirmed. Additional studies have evaluated the diagnostic thinking impact of FDG-PET with regards to patient management and diagnostic work-up of pancreatic cancer. Findings from FDG-PET lead to changes in the pre-treatment staging as well as the decisions regarding treatment management because of changes in resectability status. The majority of findings demonstrated previously unsuspected metastases and resulted in cancellation of previously planned surgical resection. Roughly half the time the newly identified metastases had not been detected by initial CT scans.

The cost-effectiveness of adding FDG-PET to the routine diagnostic procedures to determining staging and eligibility for surgery among patients with presumed resectable pancreatic cancer has been examined in a limited number of studies. Cost savings were identified primarily by identifying patients who were initially staged for surgery and later deemed ineligible because of detected metastases.

Although FDG is used extensively and successfully in many cancers, because of the targeting characteristics of this compound as a marker of glucose metabolism, the sensitivity and specificity of FDG are not optimal in all cancer types. The shortfalls of imaging with FDG, such as inadequate differentiations between post-therapy inflammation and tumor, poor imaging in slow-growing tumors, and high uptake in normal cells such as brain and gut, have remained as the justification for the development of newer PET tracers.

FDG-PET Reimbursement

The Department of Health and Human Services has completed a Technology Assessment for FDG-PET in pancreatic cancer. The Centers for Medicare and Medicaid Services, or the Center, utilized the Technology Assessment and has issued a National Coverage Determination for FDG for oncologic conditions. The Center has elected to cover the expense of using FDG-PET for the diagnosis and staging of pancreatic cancer. However, the Technology Assessment found insufficient support for fully covering FDG-PET for restaging and monitoring response to treatment. Private insurance carriers follow the Center’s recommendation and cover FDG-PET for diagnosis and staging.

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Potential Market Opportunity

To our knowledge, the radiolabeled 5B1 antibody represents one of the only agents in development specifically aimed at improving imaging in pancreatic cancer. Since the antigen targeted by the 5B1 antibody is significantly and preferentially over expressed on metastatic pancreatic cancer, this development effort represents a potentially important step forward in the diagnosis, staging, and assessment of the majority of pancreatic cancer patients. Using an imaging agent that is specific for a pancreatic cancer antigen would be greatly preferable to an indirect marker that can produce false positive results in high metabolic rate tissues (tissues where there is an elevated metabolism of sugar due to a variety of causes including cancer) or a false negative in slow growing cancers. We believe that the market opportunity for a 5B1 antibody-based radiopharmaceutical is significant in multiple ways. First the ability of physicians to accurately diagnose, stage, and assess treatment outcomes in pancreatic cancer would be very important. Accurate determinations on extent of disease and resectability are essential to improving outcomes in this cancer. We believe improvements in the sensitivity and specificity of one of the primary diagnostic tools would be useful and that potentially almost all patients diagnosed with pancreatic cancer could benefit from a  ⁸⁹ Zr-hu5B1 antibody scan. Using existing utilization and reimbursement rates for the current standard of care product, FDG-PET, annual revenues for a 5B1 antibody-based radiopharmaceutical could exceed $100 million per year. Since the regulatory pathway is significantly less expensive and time consuming than a therapeutic agent, we believe that this companion diagnostic product opportunity will complement the full-length therapeutic antibody and antibody-drug conjugate products.

This project is also important to us because of the potential enablement of the full-length therapeutic antibody. The  ⁸⁹ Zr-hu5B1 antibody will be essential in the clinical development of the 5B1 antibody. It would help improve our understanding of the antibody’s in vivo behavior including the interaction with its critical disease target, mechanism of action, distribution, and potential toxicities. Just as important, we believe the 5B1antibody-based radiopharmaceutical would enable physicians to identify patients with the greatest chance of benefiting from treatment with the antibody and that the 5B1Db-based radiopharmaceutical would enable accurate diagnosis, staging, and assessment of treatment outcome of a new antibody treatment for advanced pancreatic cancer.

License Agreement with MSKCC

We have licensed from MSKCC the exclusive world-wide developmental and commercial rights to all antibodies we discover using lymphocytes (immune system cells from with antibodies are secreted) from vaccinated clinical trial participants enrolled in any of the clinical trials involving the vaccines licensed to us. MSKCC has issued patents or has patents pending on all underlying vaccines. This patent portfolio includes 35 issued patents in the US and rest of world along with 7 patent applications. We own all monoclonal antibodies produced by the antibody discovery program and these antibodies are generally patented once their potential therapeutic utility has been sufficiently demonstrated in animal models. A provisional patent application for the anti-sLe ^a  antibodies described in this application has been filed.

We are unique in that only a very small number of oncology focused companies are vaccinating patients with carbohydrate-based vaccines intended to elicit an antibody response and, to the best of our knowledge, we are the only company deriving antibodies from the lymphocytes of vaccinated patients. Since these carbohydrates are very difficult to make immunogenic and the carbohydrates cannot be easily manufactured, it is very difficult if not impossible to find a source for human antibodies to these antigens beyond that utilized by us.

Vaccine Program

We have licensed exclusive rights from MSKCC to exploit key aspects of the work of Dr. Livingston (who is also a member of our board of directors) and colleagues, who over the last 30 years have developed a series of monovalent (targeting a single tumor cell surface antigen) cancer vaccines against cancers of neuroectodermal and epithelial (breast, ovarian colon, pancreatic) origin as well as small cell lung cancer, or SCLC. These target molecules on malignant cells, known as carbohydrate antigens, are the most extensively expressed antigenic targets on the cell surface of these types of cancers and play a key role in tumor progression and metastasis. We expect to benefit from the years of work and significant expense already invested in the development and testing of the vaccines incorporating these antigens. Researchers at MSKCC have progressively developed highly immunogenic monovalent vaccines to each of the 11 validated target antigens that comprise the licensed vaccines. These monovalent vaccines or the combination of the monovalent forms into polyvalent vaccines (targeting multiple antigens) have been tested and refined not only in animal models but also in multiple clinical trials establishing immunogenicity, tolerability, and therapeutic utility. Our license agreement with MSKCC calls for MSKCC to complete all preclinical and Phase I clinical trial work at MSKCC’s expense at which point the Investigational New Drug Application, or IND, would be transferred to us for continued development.

Our lead cancer vaccines targeting recurrent sarcoma and ovarian cancer are currently in proof of concept Phase II multi-center clinical trials. Both trials are fully enrolled, and have received substantial federal grant monies to support their development.

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A vaccine to address the orphan disease neuroblastoma has completed an initial Phase I trial at MSKCC yielding encouraging results. We expect the vaccine product to be ready for a Phase II trial by early 2015. MSKCC and MabVax Holdings have completed additional Phase I vaccine clinical trials in melanoma, ovarian cancer, and small cell lung cancer over the last three years.

Our Vaccines Intend to Address Recurrent Cancer, An Unmet Medical Need

Despite undergoing potentially curative surgical resection or combination therapy, a significant number of patients with cancer will have their cancer recur. Patients with recurrent cancer have a significantly lower survival rate and incur much higher medical costs compared to those whose disease does not recur. Multiple clinical studies have demonstrated that additional courses of chemotherapy or radiation in the adjuvant setting do not or only minimally improve outcomes for these patient groups. Thus, in the majority of cases, the current standard of care following treatment of metastatic disease and the achievement of disease-free status is watchful waiting. With recurrence rates of 95% in stage IV sarcoma and 70% in stage III and IV ovarian cancer respectively, there is an unmet medical need for new treatments for recurrent disease.

Medical Solution and Rationale

According to an article in Human Vaccines by Livingston and colleagues published in 2006, the adjuvant setting is the ideal time for immune intervention and in particular for administration of monoclonal antibodies or cancer vaccines aimed at instructing the immune system to identify and kill the few remaining circulating cancer cells. We believe that passively administered or vaccine induced antibodies against selected cell surface antigens are ideally suited for eradication of free tumor cells and micrometastases. This is the role of antibodies against most infectious diseases, which has been accomplished against cancer cells in a variety of pre-clinical models and recent clinical trials. We also believe that if antibodies of sufficient titer can be administered or induced against tumor antigens to eliminate tumor cells from the blood and lymphatic systems and to eradicate micrometastases, this could dramatically change the approach to treating the cancer patient. If successful, establishment of new metastasis would no longer be possible, so aggressive local therapies including surgery or radiation therapy, and intralesional (injection of cancer treatment directly into a tumor) treatments, combined with our immunotherapeutic agents could result in long term control of metastatic cancers.

Vaccine Purpose Determines Vaccine Design

According to Livingston’s article in Human Vaccines, the majority of carbohydrate antigens are recognized exclusively by B-lymphocytes and antibodies and the optimal approach for augmenting antibody responses against defined antigens involves conjugation of the antigens to a highly immunogenic carrier protein. This is the approach currently used in a variety of vaccines against bacterial pathogens and is the approach we believe to be optimal for cancer associated carbohydrate antigens (antigens/targets made of carbohydrates; also known as sugar structures) as well.

We have explored a variety of methods for augmenting the antibody response to defined antigens including vaccine production with autologous (derived from a subject’s own cells) or allogeneic (derived from another subject’s cells) tumor cell lines or lysates, the use of multiple different immunological adjuvants, chemical modification of antigens to render them more immunogenic, conjugation to different immunological carrier proteins and adherence of antigens to a variety of vehicles including liposomes (artificial structures that can carry active agents into the body), polystyrene beads (small synthetic beads), BCG and Salmonella. The conclusions from these studies are that the use of an immunogenic carrier protein plus a potent immunological adjuvant is the optimal approach. The studies established that the optimal carrier protein was KLH, while the optimal adjuvants were saponins (class of adjuvants) such as QS-21 or OPT-821obtained from the bark of Quillaia saponaria (type of tree indigenous to South America). Both conjugation to KLH and use of a saponin (substance derived from Quillaia saponaria) adjuvant are required for an optimal response. The role of the carrier protein in these conjugate vaccines was induction of a potent T-cell response against KLH, resulting in a cascade of cytokines (immune system cells essential to immune response) which then provide help for the antibody response against both KLH and more weakly immunogenic molecules attached to KLH. The primary role of the saponin adjuvants appeared to be augmentation of the immune response against KLH.

Previous Human Clinical Experience

There are an increasing number of clinical trials showing that passively administered monoclonal antibodies, or mAbs, against cell surface antigens such as HER2/neu, EGF receptor, VEGF, CD20, CD33 and CD52 have demonstrated clinical efficacy against human cancers and leukemias. Specifically, according to an article in Clinical Breast Cancer by Jahanzeb there is evidence from a series of recently described clinical trials with Trastuzumab (Herceptin ^® , against HER2/neu) used in breast cancer patients in the adjuvant setting confirming a striking recurrence free and overall survival advantage. This is a more dramatic response than seen with the same mAb used in the more advanced disease setting. Finally, naturally acquired or vaccine induced antibodies

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against cancer cell surface antigens such as GM2 and sTn have correlated with improved prognosis in several different clinical settings. Murine (mouse origin) monoclonal antibodies 3F8 against GD2 and R24 against GD3 have each induced clinical responses in a significant proportion of melanoma patients in the advanced disease setting. 3F8 and R24 are murine monoclonal antibodies and so can only be administered briefly before human anti-mouse antibodies, or HAMA, induction leads to decreased clinical availability.

There has been a significant amount of clinical work in the development of the monovalent and polyvalent versions of these cancer vaccines that stretches over two decades. In the Investigator’s Brochure portion of the INDs submitted to FDA on behalf of the sarcoma and ovarian cancer vaccine trials, we list the 30 Phase I clinical trials testing immunogenicity and tolerability of each of the monovalent vaccines to date. Refinements in antigen configuration, selection of carrier molecules, selection of adjuvant, vaccination schedules, and dose ranging have all lead to the optimal configuration of the current vaccines. According to Livingston’s article in Human Vaccines, the current monovalent vaccines all induce an immune response of IgM and IgG antibodies capable of killing targeted cancer cells.

Concern for Autoimmune Disease

Antigens on cancer cells are generally either autoantigens or slightly modified autoantigens (antigens or targets that do not trigger an immune response) so autoimmunity is a concern with any cancer vaccine. This concern is either as a consequence of cross reactivity of the specific immune response generated against cancer antigens (also present on normal organs) or as a consequence of immune modulation resulting from the immunological adjuvant or other components of the vaccine that may generate non-specific immune modulation. These concerns are largely mitigated, however, by the extensive experience and low toxicity profile consistently observed with the individual components of this vaccine in the clinic either alone or paired up with other components of this vaccine.

The Basis for Polyvalent Immunotherapy

There are at least three reasons for the expectation that carbohydrate vaccines against cancer should contain multiple antigens (be polyvalent). First, heterogeneity is an essential feature of malignancy with patient-to-patient tumor variability and even cell-to-cell heterogeneity in the same tumor is the norm. Second, heterogeneity also characterizes the immune responsiveness of immunized hosts as a consequence of a variety of known and unknown factors including previous immunologic experience and genetic background. The final basis for polyvalent vaccines is a consequence of the previous two reasons. Anti-tumor effector mechanisms are proportional to the amount of antibody bound to the cell surface, which will in turn be proportional to the number of different antigens in the vaccine.

Addressing the issue of tumor heterogeneity will also inform our decisions regarding which antibody candidates to develop. We expect that our current work aimed at improving the quality and control of manufacturing monoclonal antibodies will eventually allow us to explore the development of “cocktails” of mAbs which in turn would allow us to continue to improve the utility of antibodies against various cancers.

Sarcoma Vaccine

Background

Sarcomas are rare neoplasms (tumor that has caused a lump) that arise from the mesenchymal (connective tissue such as bone or cartilage) tissues of the body. According to the NCI’s website, in the United States, there are approximately 13,000 cases diagnosed each year, representing less than 1% of all new cancers. Of these sarcomas, roughly 80% originate from soft tissue, with the remainder originating from bone. Prognosis remains poor, with more than 5,000 patients in the US dying of disease each year. The overall prevalence of sarcoma patients in the US is thought to be approximately 100,000.

As in other malignancies, disease recurrence and metastasis are common in sarcoma. Metastases may involve any organ of the body, but, according to the NCI’s website approximately 20% of adult patients with extremity sarcomas will have isolated lung metastasis at some point during their disease course, with some amenable to complete surgical resection. Additional patients will have solitary or oligometastatic (cancer that has spread to multiple locations throughout the body) disease affecting other sites of the body that will be amenable to complete resection. Favorable prognostic indicators in recurrent sarcoma include a long disease-free interval from the time of primary resection, the number and location of metastatic lesions, and a long tumor doubling time.

Osteosarcomas (bone based sarcomas), rhabdomyosarcomas (sarcomas arising from muscle tissue), and other non-rhabdomyosarcomas such as Ewing sarcoma (tumor arising in bone or soft tissue and primarily occurring in teenagers and young adults) are high-risk sarcomas that occur most commonly in teens and young adults. According to the NCI’s website, approximately 30% of patients will present with metastases or recur following initial therapy for metastatic disease. These recurrences are generally treated with a combination of chemotherapy, surgery, and/or radiotherapy, with more than 90% of these patients achieving a complete response to therapy according to the NCI’s website.

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Despite undergoing potentially curative surgical resection or combination therapy, according to an article by DA Potter and colleagues published in the Journal of Clinical Oncology in 1985, the majority of recurrent sarcoma patients die as a result of further recurrences. The overwhelming majority of pediatric patients ultimately succumb to their disease following the development of recurrent, chemoresistant disease, and their prognosis remains unacceptably poor despite aggressive multimodality treatment. The addition of chemotherapy to surgical resection has not been shown to improve outcome in adult sarcomas. Thus, in the majority of cases, the current standard of care following treatment of metastatic disease and the achievement of disease-free status is expectant management.

Sarcoma Vaccine Clinical Program

We initiated a randomized, multicenter, double-blind Phase II clinical trial in July of 2010. A total of 136 patients were enrolled. Patients who entered the study had stage IV metastatic disease and were cleared by surgery. Patients were vaccinated 10 times over 84 weeks and monitored throughout the study period. The study was powered to show a statistical improvement in both progression free survival (measured at the mid-point of the study) and overall survival. In October of 2013, MabVax Holdings presented the mid-point results to the independent Drug Safety Monitoring Board, or DSMB. The DSMB concluded that there were no unanticipated or clinically worrisome safety concerns. Injection site reactions were the most common adverse events followed by fatigue, fever, and flu-like symptoms. In addition, the DSMB recommended that investigators and patients should remain blinded as to treatment assignment and the patients should continue to be followed to assess overall survival. In addition, given the acceptable safety profile observed in both arms of the study, the DSMB recommended that after investigators and patients are informed of the (blinded) results of this analysis and with their consent, the last of the patients still receiving vaccinations should be allowed to continue treatment.

In this study, the sarcoma vaccine elicited an antibody response intended to kill circulating tumor cells and micrometastases in all but one of the vaccinated patients. However, the DSMB concluded that the study did not reach statistical significance for its primary efficacy endpoint of a 50% improvement in time to recurrence. The study has not yet accumulated a sufficient number of events to evaluate the secondary endpoint of overall survival. Based on our discussions with the FDA prior to the initiation of the study, the overall survival endpoint will be considered the primary endpoint for the measurement of efficacy. As such we plan to follow all patients in the study until sufficient numbers of events (deaths) have occurred to allow analysis of this endpoint. We expect that the event threshold will be reached in 2016.

Potential Commercial Opportunity

Sarcomas are a diverse group of malignant tumors that develop from fat, muscles, nerves, joints, blood vessels, bones, and deep skin tissues. Soft tissue sarcomas are more deadly in part due to the lack of detectable symptoms at early disease stages and prognosis remains poor, with more than 5,000 patients in the US dying of disease each year according to the National Cancer Institute, or NCI. The NCI estimates 5-year survival rates of 60%. Additionally, according to the NCI, an article in CA: A Cancer Journal for Clinicians by A. Jemal published in 2006, and articles published by the American Cancer Society, the overall prevalence of sarcoma patients in the US is thought to be approximately 100,000, recurrence rates vary depending on the particular subtype of sarcoma but generally range from 30% to 50% and patients whose sarcoma recurs have a significantly poorer prognosis which declines even further as the number of recurrences increase over the course of the disease.

The current standard of care for patients who have been successfully treated for their cancer and rendered free of detectable disease is watchful waiting. According to an article in The Lancet Oncology in 2012, additional treatments of chemotherapy or radiation have not been proven to prevent or prolong the time to onset of cancer recurrence. Consequently, we anticipate that the sarcoma vaccine will be added as an additional treatment to the current treatment paradigm and not displace an existing treatment. We expect that patients who have experienced one or more recurrences will be the initial candidates for vaccine therapy. This would be consistent with the early clinical trials. Over time, as the product demonstrates utility, we anticipate that usage will migrate toward earlier and earlier treatment to include patients who have been diagnosed and treated for sarcoma but not yet experienced a recurrence in an effort to block the progress of the cancer at an earlier and more likely productive time period.

We have estimated the ex-manufacturer price for this therapy at $30,000 to $50,000 per course of treatment, and an average estimated cost of cancer therapy of $32,000. Treatment is defined as a course of 10 vaccinations over 84 weeks as per the Phase II clinical trial protocol. Standard of care calls for patient check-ups quarterly after successful initial treatment to achieve the minimal disease status. The first 5 vaccinations require visits to the physician more frequently than quarterly but beyond that initial treatment sequence, the remaining vaccinations are delivered at the time of the standard check-up. Treatment can be given in the physician office setting with no special administration equipment required. The cost of the proposed vaccine therapy can be favorably compared to cycle costs for targeted vaccine and monoclonal antibody products ranging from $20,000 to $100,000 per

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treatment cycle. According to the NCI, the average monthly direct cost of all cancer treatments across all cancers studied was $2,647 per month and the total cost for treatment was more than $32,600. There are substantial indirect costs associated with hospitalizations, short-term disability, and absenteeism resulting from cancer recurrence that can drive treatment costs higher. We project that annual revenue from a sarcoma vaccine could range from $150 million to $300 million annually based on internal projections considering the number of patients, the percentage of patients with metastatic disease, the cost of treatment, and market penetration rates.

The ultimate success of the sarcoma vaccine will depend on several factors, including, but not limited to the following: (i) The percentage of patients whose cancer does not recur or for whom recurrence is delayed, (ii) In those patients who respond to the vaccine, whether the prevention of recurrence or the delay of recurrence is for a clinically meaningful period of time, and (iii) The willingness of third-party payers and the government to pay for the addition of the vaccine therapy to the existing treatment paradigm. The clinical development program should answer the first two questions positively. As with almost all new therapies in cancer, the last question will require a substantial amount of work with these important participants in the healthcare system. If we can demonstrate reduced recurrence rates in sarcoma, we believe we can also demonstrate the financial benefits of reduced or unnecessary further treatments when recurrent sarcoma is prevented or delayed.

Ovarian Vaccine Program

Background

According to the NCI, ovarian cancer is the most lethal gynecologic cancer. According to materials available on the NCI’s website there are more than 21,800 new cases each year with almost 14,000 deaths per year. It is estimated that there are 174,000 surviving ovarian cancer patients. Recurrence rates are extremely high at 70% and 5-year survival is still very poor at just over 40%. The current standard treatment for patients with advanced ovarian cancer consists of aggressive surgical cytoreduction (resection of a tumor to the extent possible followed by radiation treatment) followed by taxane (chemical anti-cancer drug) and platinum-based chemotherapy. While the median overall survival for optimally debulked patients has increased to 65.6 months, less than 30% of patients will remain free of disease. Many patients will have chemotherapy-sensitive disease initially at recurrence, and can reenter successive remissions with additional treatment. Subsequent remissions are of progressively shorter duration until chemotherapy resistance uniformly develops. We believe that immune directed therapy is ideally suited for patients who are in clinical remission when the disease burden is lowest, and evaluating treatments designed to prolong the duration of such remissions remains a high priority. We also believe that antibodies are well suited for eradicating tumor cells from the bloodstream and eliminating early tissue invasion. Preclinical models have demonstrated the clearance of circulating tumor cells and the elimination of systemic micrometastasis through the use of both passively administered and vaccine induced antibodies.

Ovarian cancers express a rich array of cell-surface antigens. These include carbohydrate epitopes such as GM2, Globo-H, Lewis ^y , sialyl Tn, or STn, Tn, Thompson Friedreich antigen, or TF, and mucin 1, or MUC1. According to an article in Cancer Immunology Immunotherapy written by Livingston that was published in 1997, for the production of antibodies against defined cell-surface antigens such as these, the best approach has been described to include chemical conjugation of the antigen to a highly immunogenic carrier protein plus the use of a potent immunological adjuvant. The best carrier protein in our experience has been keyhole limpet hemocyanin (a sea creature such as a limpet or snail from which copper-based highly immunogenic blood is extracted), or KLH, and the best immunological adjuvant has been a saponin such as QS-21 or OPT-821. Pre-clinical data supports the hypothesis that polyvalent vaccines will likely be required due to tumor cell heterogeneity, heterogeneity of the human immune response, and the correlation between overall antibody titer against tumor cells and antibody effector mechanisms.

Ovarian Vaccine Clinical Program

A randomized, multicenter, double-blind Phase II clinical trial in ovarian cancer with a pentavalent (a vaccine that has multiple antigens) vaccine was initiated in July of 2010. While this vaccine was included in the group of vaccines exclusively licensed to us in 2008, a NIH grant award co-authored by Dr. Philip Livingston was made which fully funded the planned Phase II clinical trial. Management of the trial was assigned to the Gynecologic Oncology Group, or GOG. We contributed to the development of the IND and provided financial support for the manufacture of the clinical material. A total of 164 patients were enrolled. Patients who entered the study had metastatic ovarian cancer and have been treated with cytoreductive surgery and chemotherapy. They were in complete clinical remission as defined by CA-125 levels within normal, negative physical examination and no evidence of disease by CT scan. Patients were vaccinated 10 times over 84 weeks and monitored throughout the study period. The study was powered to show a statistical improvement in both progression free survival (measured at the mid-point of the study) and overall survival. The study has not achieved a sufficient number of events to trigger the mid-point analysis. Based on discussions with the principal investigator, the GOG plans to recommend that investigators and patients remain blinded as to treatment assignment and the patients should continue to be followed to assess overall survival. MabVax Holdings anticipates that results from the overall survival endpoint will be announced in 2016.

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Potential Commercial Opportunity

We have estimated that the ex-manufacturer price for this therapy to be $40,000 per course of treatment. Treatment is defined as a course of 10 vaccinations over 84 weeks as per the Phase II clinical trial protocol. Standard of care calls for patient check-ups quarterly after successful initial treatment to achieve the minimal disease status. The first 5 vaccinations require visits to the physician more frequently than quarterly but beyond that initial treatment sequence, the remaining vaccinations are delivered at the time of the standard check-up. Treatment can be given in the physician office setting with no special administration equipment required. The cost of the proposed vaccine therapy can be favorably compared to cycle costs for targeted vaccine and monoclonal antibody products ranging from $20,000 to $100,000 per treatment cycle. The average monthly direct cost of all cancer treatments across all cancers studied was $2,647 per month and the total cost for treatment was $32,629. There are substantial indirect costs associated with hospitalizations, short-term disability, and absenteeism resulting from cancer recurrence that can drive treatment costs higher. We project that annual revenue from an ovarian vaccine could range from $200 million to $400 million annually.

The ultimate success of the ovarian cancer vaccine will depend on several factors including, but not limited to: (i) The percentage of patients whose cancer does not recur or for whom recurrence is delayed, (ii) In those patients who respond to the vaccine, whether the prevention of recurrence or the delay of recurrence is for a clinically meaningful period of time, and (iii) The willingness of third-party payers and the government to pay for the addition of the vaccine therapy to the existing treatment paradigm. The clinical development program should answer the first two questions positively. As with almost all new therapies in cancer, the last question will require a substantial amount of work with these important participants in the healthcare system. If we can demonstrate reduced recurrence rates in sarcoma, we believe we can also demonstrate the financial benefits of reduced or unnecessary further treatments when recurrent sarcoma is prevented or delayed.

Neuroblastoma Vaccine

Introduction and Overview

Neuroblastoma is the most common extra-cranial solid tumor in children. According to the NCI and an article in the Annals of Pharmacology by Parsons and colleagues in 2013, there are approximately 700 new cases per year in the United States so it is certainly an orphan disease. According to the NCI SEER data, patients with high risk features, defined by clinical and tumor biologic parameters at diagnosis have an expected survival of only 45% despite intensive induction chemotherapy (very high dose chemotherapy), surgical resection, myeloablative consolidation chemotherapy with stem cell support, radiation,(radiation doses intended to eliminate the immune system of the patient followed by stem cell reconstitution of the system) focal radiation (precise pin-point radiation doses) and post-consolidation treatment (chemotherapy treatment post resection), with 13-cis-retinoic acid, or cisRA, and anti-GD2 mAb ch14.18 immunotherapy. MabVax Holdings believes that these results, plus the potentially severe toxicities of chemotherapy and radiotherapy, are compelling reasons for pursuing novel therapeutic approaches.

In particular we believe that, there is a need for therapies that selectively eliminate neuroblastoma cells in the setting of minimal or limited amounts of residual disease following intensive induction therapy. According to an article in Clinical Cancer Research by Matthay and Yu in 2012, neuroblastoma is unique in its abundant expression of the gangliosides GD2 and GD3. Each of these antigenic targets is an outstanding target for immune attack against neuroblastoma cells. In experimental animal studies conducted by Livingston and Ragupathi, administered or vaccine-induced antibodies against GD2, GD3 and other cell surface antigens were able to eliminate micrometastasis in settings similar to the treatment of patients in complete remission but with a high likelihood of relapse. The basis for emphasis on a bivalent (having two antigens raising an immune response to two targets) vaccine containing each of these agents are tumor cell heterogeneity, heterogeneity of the human immune response and the correlation between overall antibody titer against the tumor cell surface and effector mechanisms such as opsonization, complement-dependent cytotoxicity (how antibodies marshal other immune system cells to kill the cells to which they have attached, or CDC, or antibody dependent cellular cytotoxicity, or ADCC.

Vaccines based on self-antigens such as these three must be potently immunogenic to overcome immune tolerance and tumor-mediated immune suppression. Based on the results of studies discussed by Livingston in an article published in 2006 in Human Vaccines, the most effective vaccine for breaking tolerance in man appears to be composed of the tumor-associated self-antigen conjugated to a highly immunogenic carrier protein such KLH combined with a potent saponin adjuvant. Monovalent KLH conjugate vaccines against GD2, and GD3 (plus saponin adjuvant) have been constructed, tested and optimized in patients with melanoma or small cell lung cancer. Each induces high titers of antibodies against the immunizing antigen and against tumor cells expressing these antigens in most patients and these antibodies mediate effector mechanisms such as CDC and ADCC. The minimal optimal dose of each has been determined and safety confirmed through multiple Phase I studies. In addition, a Phase I trial of a bivalent vaccine containing GD2-KLH, GD3-KLH and escalating doses of saponin adjuvant co-administered with oral ß-glucan in children with neuroblastoma has been completed (Kushner, et. al.) Safety, immunogenicity and the optimal saponin adjuvant dose were determined and the vaccinated subjects in this study were noted to have an unexpectedly favorable outcome. Finally, a Phase II randomized, multicenter, double blind trial of a trivalent ganglioside vaccine plus saponin adjuvant is currently underway in subjects with sarcoma who are disease-free after resection of metastatic disease. We believe that this collective experience provides the rationale for undertaking the current study in high-risk neuroblastoma subjects who are in second or subsequent complete remission or have only limited residual disease.

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Results of a Recent Phase I trial of Bivalent Vaccine in Combination with Oral ß-glucan

MSKCC carried out a Phase I trial in subjects with high-risk neuroblastoma to assess the toxicity of escalating doses of the immunological adjuvant OPT-821 in a bivalent vaccine containing fixed doses of GD2L and GD3L, each covalently attached to the immunological carrier protein KLH (Kushner, 2012). The study subjects were in second (or later) complete, very good partial, or partial remission. Subjects received seven subcutaneous injections over 52 weeks,

Thirteen of the 15 subjects received the entire 12 months of protocol treatment. No dose limiting toxicity was noted in any of the subjects. Most subjects had detectable anti-GD2 or anti-GD3 antibodies. Twelve remain relapse-free at 21+-36+ (median 29+) months. One had a focal relapse (recurrence of the cancer at a specific spot) (supraclavicular node) at 21 months. Two other subjects had early focal relapses (2.3 and 4.6 months). PFS was 87+9% at 12 months and 78+11% at 24 months. Overall survival is 100% (follow-up >22months). These results are in marked contrast to the expected relapse rate at 12 months of 50% to 60%.

Clinical Plan

We have received the Phase I portion of an SBIR grant for support in production of the clinical trial material required for a planned Phase II clinical trial. The Company has also established a relationship with a consortium of thirteen academic hospital based neuroblastoma treatment programs called New Advances in Neuroblastoma Therapy, or NANT. We entered into a Letter of Intent with NANT and the NANT Scientific Review Committee has reviewed our jointly developed Phase II clinical protocol which was approved by this committee with only minor modifications. Because the market opportunity for a vaccine to treat recurrent neuroblastoma is very small, we have worked to bring in additional non-dilutive financing. We hope to expand the SBIR award to the Phase II portion of the grant which could offset $1 million in Phase II clinical expenses. We are currently conducting standard release and stability testing on the recently completed clinical material. Test results will be available in the second quarter of 2015. We are planning to obtain the orally bioavailable immune system stimulant product that was used effectively in the Phase I trial at MSKCC. That product will be available later in the year. Once that last adjunctive treatment is secured, we will be able to seek an IND to initiate the clinical trial.

Patents

As of March 12, 2015, we were the exclusive licensee, sole assignee or co-assignee of 20 granted United States patents, 16 pending United States patent applications and 41 international patents through MabVax Therapeutics covering the monovalent vaccines that make up the polyvalent vaccine products. The major claims of these patents cover composition of the vaccine, methods of treatment, chemical modification of antigens, and synthesis. We also own or have rights to 2 patent applications in the United States and 6 in other geographic areas currently pending, covering aspects of ovarian cancer and breast cancer. We also have 21 granted United States patents, 12 pending United States patent applications and 99 international patents obtained, and 88 international patent applications that are also being maintained by the Company from prior to the Merger while we continue to evaluate the usefulness of these patents and patent applications to the Company.

The Intellectual Property Rights of the Company used prior to the Merger are not used in the company’s current operations. The Company may enter into one or more agreements relating to the sale or license of such Intellectual Property Rights, but is not otherwise actively maintaining any registrations or making filings required in connection with any such Intellectual Property Rights, and certain of such Intellectual Property Rights may already have expired or been deemed abandoned.