Genentech receives FDA Refuse to File letter for accelerated approval of trastuzumab-DM1 BLA

ImmunoGen, Inc. (Nasdaq: IMGN), a biotechnology company that develops antibody-based targeted anticancer products, today announced that Genentech, a member of the Roche Group, today announced its receipt of a Refuse to File (RTF) letter from the US Food and Drug Administration (FDA) for the accelerated approval of the Biologic License Application (BLA) for trastuzumab-DM1, or T-DM1, submitted in July 2010. Genentech also stated that as planned, it will continue with its ongoing Phase III registrational T-DM1 trial, known as EMILIA, and that it will continue to work with the FDA and expects to submit a new T-DM1 BLA in mid-2012.

“It is a significant disappointment that there will be a delay in the opportunity for T-DM1 to be approved for patients with advanced HER2 positive breast cancer”

Genentech noted that in its review of the BLA, the FDA stated that the T-DM1 trials did not meet the standard for accelerated approval because all available treatment choices approved for metastatic breast cancer, regardless of HER2 status, had not been exhausted in the study population. Genentech re-affirmed its confidence in T-DM1 as "an important, novel HER2-targeted medicine," and indicated that it remains fully committed to its ongoing development. In particular, as noted above, it intends to continue the EMILIA study which compares T-DM1 to lapatinib in combination with capecitabine in people with advanced, HER2-positive breast cancer whose disease has worsened after receiving initial treatment.

"It is a significant disappointment that there will be a delay in the opportunity for T-DM1 to be approved for patients with advanced HER2 positive breast cancer," commented Daniel Junius, President and CEO of ImmunoGen. "In the meantime we continue to focus on the development of our robust and expanding pipeline as well as advancing our technology through new partnerships."

The BLA submitted for T-DM1 in July 2010 requested accelerated approval for T-DM1 based on the results of a single-arm Phase II study, which showed T-DM1 shrank tumors in one-third of women with advanced HER2-positive breast cancer, who had received on average seven prior medicines, including two HER2-targeted medicines.

T-DM1 consists of ImmunoGen, Inc.'s DM1 cancer-cell killing agent attached to Genentech's HER2-targeting antibody, trastuzumab, using ImmunoGen's linker and methods of attachment. T-DM1 is in global development by Roche under a collaboration agreement between Genentech and ImmunoGen.

Updated Financial Guidance

The Company indicated that the financial guidance provided for its fiscal year 2011 on August 4, 2010, is no longer valid due to the impact of Genentech's receipt of the RTF letter and that updated guidance is being developed and will be provided at a future date.