Genentech announces positive results from Phase II study of T-DM1

Genentech, Inc., a wholly owned member of the Roche Group (SIX: RO, ROG; OTCQX: RHHBY), today announced positive results from a Phase II study of trastuzumab-DM1 (T-DM1). As assessed by independent review, T-DM1 shrank the tumors (also known as objective response) in 33 percent of women with advanced (metastatic) HER2-positive breast cancer that had worsened following previous treatment. Women in the study had already received an average of seven drugs for metastatic disease, including chemotherapy, trastuzumab and lapatinib, prior to receiving T-DM1. No new or unexpected safety signals were observed. Results were presented today at the 32nd Annual San Antonio Breast Cancer Symposium (Abstract #710).

“Despite major advances in HER2-positive breast cancer, the disease may still progress after multiple treatments, to the point where there are no approved HER2-targeted medicines,” said Hal Barron, M.D., executive vice president, Global Development and chief medical officer, Genentech. “Results from this study are promising for women who need new treatment options, and we will discuss next steps of the T-DM1 development program with the FDA.”

“These results are significant because they demonstrate that T-DM1 was effective at shrinking tumors in women whose cancer had progressed following prior treatment with standard therapies for HER2-positive breast cancer,” said Ian Krop, M.D., Ph.D., a medical oncologist at Dana-Farber Cancer Institute, and lead investigator on the study.

In this single-arm study, 45 percent of women experienced a clinical benefit (defined as a complete or partial tumor response, or stable disease, maintained for at least six months), as assessed by independent review. Adverse events were similar to those observed in previous clinical trials of T-DM1. The most common severe adverse events included thrombocytopenia (a low level of platelets in the blood, 5.5 percent) and back pain (3.6 percent), and the most common adverse events were fatigue (59.1 percent) and nausea (37.3 percent). No severe (Grade 3 or higher) cardiac-specific side effects were observed. One patient with pre-existing, non-alcoholic fatty liver disease died with hepatic failure.