ImmunoGen reports data from T-DM1 Phase III trial on HER2-positive metastatic breast cancer

ImmunoGen, Inc. (Nasdaq: IMGN), a biotechnology company with a proprietary Targeted Antibody Payload (TAP) technology, today announced results from the trastuzumab emtansine Phase III EMILIA trial conducted by Roche. Trastuzumab emtansine comprises ImmunoGen's DM1 cancer cell-killing agent linked to the trastuzumab antibody developed by Genentech, a member of the Roche Group, using ImmunoGen's method of attachment. It is in global development by Roche under an agreement between ImmunoGen and Genentech. Roche plans to apply this year for marketing approval of trastuzumab emtansine in the US and Europe using EMILIA data.    

The EMILIA 991-patient trial compares trastuzumab emtansine, used alone, to lapatinib (Tykerb®) plus capecitabine (Xeloda®) for the treatment of HER2-positive metastatic breast cancer that has progressed after treatment with trastuzumab (Herceptin®) and a taxane in any setting (early or metastatic disease).

Among the study findings reported are:

• Treatment with trastuzumab emtansine significantly improved progression-free survival (PFS) compared to treatment with lapatinib plus capecitabine, as assessed by an independent review committee. Median PFS was 9.6 months compared to 6.4 months, respectively. The hazard ratio (HR) was 0.65 (p<0.0001), meaning that trastuzumab emtansine reduced the risk of cancer progression or death by 35% relative to treatment with lapatinib plus capecitabine. PFS is a co-primary endpoint of EMILIA.
• Overall survival (OS) is also a co-primary endpoint of EMILIA, and the OS data are not mature at this time. A sufficient number of events have occurred to establish median OS for the lapatinib plus capecitabine treatment group (23.3 months) but not yet for the trastuzumab emtansine treatment group, and thus longer follow up is required.
• For trastuzumab emtansine-treated patients, estimated one-year survival was 84.7% and estimated two-year survival was 65.4%. For the patients receiving lapatinib plus capecitabine, estimated one-year and two-year survival rates were 77.0 % and 47.5%, respectively.
• Fewer trastuzumab emtansine-treated patients experienced Grade 3 or higher (severe) adverse events (AEs) than those treated with lapatinib plus capecitabine (40.8% vs. 57%, respectively). The most common of these Grade 3 or higher AEs with trastuzumab emtansine were low platelet count (12.9%), increased enzymes released by the liver/other organs (4.3% and 2.9%, depending on enzyme type), and anemia (2.7%), findings consistent with previous studies. The most common Grade 3 or higher AEs with lapatinib plus capecitabine were diarrhea (20.7%), hand-foot syndrome (16.4%), vomiting (4.5%), and neutropenia (4.3%).

The EMILIA data have been selected for presentation in a plenary session of the American Society of Clinical Oncology (ASCO) annual meeting this afternoon (Abstract #LBA1) and were also featured in the official ASCO press program.

"These results show that trastuzumab emtansine can make a notable difference for patients and their families," commented Daniel Junius, President and CEO. "We developed our TAP technology to achieve markedly better anticancer therapies and believe these data validate our approach. We look forward to Roche applying for marketing approval of trastuzumab emtansine."

In addition to EMILIA, trastuzumab emtansine is in Phase III testing for treatment of HER2-positive metastatic breast cancer in the MARIANNE and TH3RESA trials.