Genentech, ImmunoGen’s Souped-Up Antibody for Breast Cancer Passes Key Test

9/24/11Follow @xconomy

The evidence is mounting to prove the point that Genentech’s scientists have been trying to make for years—that a souped-up version of its top-selling antibody drug for breast cancer can be more effective in some cases than the original.

Genentech, the South San Francisco-based unit of Roche, and its partner, Waltham, MA-based ImmunoGen (NASDAQ: IMGN), are announcing today that their experimental drug trastuzumab emtansine reached its main goal. This study enrolled 137 breast cancer patients with a mutated form of the HER2 protein who were getting a first round of treatment for disease that had spread. The trial showed that patients on the new drug (T-DM1) were alive and able to keep their tumors from further spreading for a median of 14.2 months, compared with 9.2 months for those who were randomly assigned to the standard trastuzumab (Herceptin) and chemotherapy.

What’s equally, if not more, interesting is that patients on the new medicine also reported about half as many cases of moderate to severe side effects—about 46.4 percent on the new medicine, compared with 89.4 percent on the standard drugs. And only 7.2 percent of patients on the new drug dropped out of the study because of adverse events, compared with 28.8 percent on the standard treatments.

The results are being reported today at the European Multidisciplinary Cancer Congress in Stockholm, Sweden. Hal Barron, Genentech’s chief medical officer, called the results “very exciting” in a company statement.

“Herceptin is a great drug, but we think we can be doing even more for patients,” says Genentech spokeswoman Krysta Pellegrino.

The results come from a mid-stage clinical trial, so Genentech still has to bolster its case through a series of ongoing pivotal trials before this drug can be cleared for sale by the FDA. But it’s an important step in the journey for this new drug, which is seeking to become part of an emerging class of therapies that combine an antibody’s ability to zero in specifically on cancer cells along with a toxin that’s supposed to deliver a knockout punch to tumors. If Genentech can confirm these results in these pivotal studies, then it could be in position to seek FDA approval for this “supercharged” version of Herceptin. The original has been a huge boon to the company, producing more than $5 billion in annual worldwide sales, and analysts predict this new version will be huge, too. ImmunoGen, which helped develop the technology to link the antibody to the toxin, stands to collect royalties on worldwide sales if the new drug reaches the market.

About one year ago, researchers reported some interim results that hinted that Genentech was on the right track with this drug. Back then, researchers said … Next Page »

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