ITEM 8.01. – OTHER EVENTS

On May 15, 2019, ImmunoGen, Inc. (also referred to as “we” and “us”) disclosed that the United States Food and Drug Administration (FDA) has recommended that we conduct a new Phase 3 randomized trial to evaluate the safety and efficacy of mirvetuximab soravtansine in patients with high folate receptor alpha (FRα)-positive, platinum-resistant ovarian cancer as a part of a Type C meeting held this week.

We requested the meeting to discuss the results of the Phase 3 FORWARD I trial and a potential path to registration for mirvetuximab monotherapy. FDA advised that, because FORWARD I did not meet its primary endpoint under the pre-specified statistical analysis plan, the data generated assessing the secondary endpoints from the study could not be used to support an application for accelerated approval. FDA acknowledged that platinum-resistant ovarian cancer is a disease with unmet need, provided guidance regarding the design and endpoints of a potential registration study, and encouraged us to return to discuss a proposed study design.

Based on the feedback received from FDA, we are evaluating potential next steps with mirvetuximab monotherapy in platinum-resistant ovarian cancer patients with high FRα expression levels. In parallel, we have generated encouraging data with mirvetuximab combination regimens and will evaluate our ongoing studies as an independent path forward to support a registration in ovarian cancer.

Forward-Looking Statements

This report includes forward-looking statements based on management's current expectations. These statements include, but are not limited to, our expectations with respect to the future development of mirvetuximab soravtansine as a monotherapy or in combination regimens. For these statements, we claim the protection of the safe harbor for forward-looking statements provided by the Private Securities Litigation Reform Act of 1995. Various factors could cause our actual results to differ materially from those discussed or implied in the forward-looking statements, and you are cautioned not to place undue reliance on these forward-looking statements, which are current only as of the date of this report. It should be noted that there are risks and uncertainties related to the development of novel anticancer products, including risks related to preclinical and clinical studies, their timings and results, and the potential that earlier clinical studies may not be predictive of future results. A review of these risks can be found in our Annual Report on Form 10-K for the year ended December 31, 2018 and other reports filed with the Securities and Exchange Commission.