Genentech, ImmunoGen 'Smart Bomb' for Breast Cancer Clears Big ...

Luke Timmerman3/30/12

Genentech has been saying for years that it has confidence in a?supercharged version of its hit breast cancer drug, and today it cleared a?major hurdle on the way to making it?a?reality.

The South San Francisco-based company, a?unit of Roche, said today that trastuzumab emtansince (T-DM1) passed its biggest clinical trial yet, a?study of 991 women with metastatic breast cancer that overexpresses the HER2 protein, and who have previously been treated with the original trastuzumab (Herceptin) and a?taxane chemotherapy. The trial, called Emilia, randomly assigned women to get either T-DM1 or a?combination of GlaxoSmithKline?s lapatinib (Tykerb) and a?chemo drug called capecitabine (Xeloda).

Full details weren?t released today, but Genentech said its new drug met the study?s goal, keeping tumors from spreading for a?significantly longer time than the drugs in the control group. Safety results were consistent with what was seen in prior studies, the company said. Even though the company hasn?t yet followed patients long enough to see if the new drug can extend lives, Genentech said the data was compelling enough for the company to file an application seeking FDA approval of T-DM1 this year, and Roche plans to do the same in Europe. About 229,000 women in the U.S. are diagnosed with breast cancer each year, and the new drug, if approved, could be a?potent new option for about one-fourth of patients whose tumors overexpress the HER2?protein.

?While prior data clearly showed the efficacy and safety of T-DM1 in both first and third line breast cancer, no data was previously available to directly compare the efficacy of T-DM1 to Tykerb/Xeloda,? said Jason Kantor, an analyst with RBC Capital Markets, in a?note to clients today. ?While we believe most investors assume EMILIA would be positive, for us, the results are an important derisking?event.?

T-DM1 is interesting not only for breast cancer patients, but for scientists, because of its unusual way of attacking cancer cells. Genentech has had huge success over the years with its original antibody, trastuzumab (Herceptin), which precisely targets the HER2 protein. But scientists there, along with collaborators at Waltham, MA-based ImmunoGen, believed they could give the drug even more tumor-killing punch if they could attach a?potent toxin to the antibody, making it sort of like a?heat-seeking missile.

Genentech previously sought FDA approval on a?smaller body of evidence from mid-stage clinical trials, and was turned down in August 2010. Since then, Genentech has beefed up the body of evidence for the drug, showing T-DM1 beat its own original product in a?head-to-head study of 137 patients, in addition to the results from today?s bigger Emilia study. And the company isn?t stopping there, running two more Phase III clinical trials of T-DM1 in a?couple different?settings.

Even though Genentech is responsible for development, and will keep the vast majority of product revenues for itself, today?s result is an important moment for ImmunoGen. The company stands to collect a ?mid-single digit? percentage royalty on worldwide sales from T-DM1, because of its contribution to help link the antibody to the toxin. ImmunoGen has no products of its own on the market, and the approval of T-DM1 would provide a?significant percentage from a?potential multi-billion dollar?seller.

Shares of ImmunoGen (NASDAQ: IMGN) climbed 9?percent to $15 at 10:19 am Eastern?time.

Luke Timmerman is the National Biotech Editor of Xconomy. E-mail him at ltimmerman@xconomy.com or follow him on Twitter at @ldtimmerman.

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