Genentech, ImmunoGen Souped-Up Breast Cancer Drug Extends Lives

Xconomy San Francisco — 

Genentech dominated the headlines with its “souped-up” breast cancer drug at the big American cancer meeting in the spring. Now it’s making headlines again this fall at a European cancer meeting with some new details about the drug.

The South San Francisco-based biotech company said today that its experimental drug trastuzumab emtansine (T-DM1) was able to extend lives in a study of 991 women with breast cancer that overexpresses the HER2 protein, and who have previously been treated with the original trastuzumab (Herceptin) and a taxane chemotherapy. People who got the new drug lived a median time of 30.9 months, compared with 25.1 months for those who were randomly assigned to get GlaxoSmithKline’s lapatinib (Tykerb) and Roche’s chemo drug capecitabine (Xeloda). Researchers reported that about 40.8 percent of patients suffered moderate to severe side effects on the new drug, compared with 57 percent in the comparison group.

The 5.8 extra months of median survival time is significant by cancer drug development standards, and the trial results are now the centerpiece of applications for approval in the U.S. and Europe. The drug is important for Genentech as the first in a new wave of antibody-drug combo molecules that are designed to be more potent than conventional targeted antibodies, and because the product should build on its success with the original trastuzumab (Herceptin). The product is also being closely watched by Waltham, MA-based ImmunoGen (NASDAQ: IMGN), which provided Genentech a technology license to help develop T-DM1, and it stands to collect a royalty on worldwide sales of the drug.

The new drug has created a lot of buzz this year, after researchers reported in June at the American Society of Clinical Oncology that the drug met its main goal of slowing the spread of tumors. The trends at that time suggested the drug would also extend lives, but researchers said more follow-up time was required before the full statistical analysis could be done. The final survival data was presented today at the European Society of Medical Oncology in Vienna, Austria.

Simos Simeonidis, an analyst with Cowen & Co., said in a note to clients that he expects the drug to win FDA approval by the end of February, when the agency has a deadline to complete its review. Genentech has already reported that the drug showed a survival advantage in the trial, but today’s presentation is the first time it has disclosed the magnitude of the benefit compared with standard treatments.

“The robustness of the data, resulting in almost a 6-month improvement in overall survival, is one more datapoint supporting our view of T-DM1 as a very active drug, with an improved safety profile,” Simeonidis said.