ImmunoGen and Genentech “Empowered Antibody” Cancer Drug Fails to Garner Accelerated Approval from FDA

8/27/10Follow @xconomy

[Updated, 8/27/10 at 5:00pm] The FDA has refused to review an application for accelerated approval of the breast cancer drug T-DM1, developed by Genentech, the South San Francisco unit of Swiss drug giant Roche, with technology from ImmunoGen (NASDAQ: IMGN), a Waltham, MA-based maker of cancer-fighting therapies, the companies announced today. [Editors Note: This sentence has been updated to clarify that ImmunoGen is not directly a developer of T-DM1 but has licensed its technology to Genentech.]

T-DM1, known as an “empowered antibody,” combines Genentech’s existing antibody drug trastuzumab (Herceptin) with ImmunoGen’s cancer-killing toxin DM1, for an added punch. The FDA stated that the souped-up drug did not meet the requirements for accelerated approval because all other treatments choices had not been exhausted for the patients with metastatic breast cancer who participated in the clinical trials of the drug.

Genentech submitted its application for accelerated approval for T-DM1 in July, based on clinical trial data showing that the drug had helped partially or completely shrink tumors in roughly one out of every three patients, in a group of volunteers who had already received an average of seven different drugs for their cancer. The data was presented in December at the San Antonio Breast Cancer Symposium.

ImmunoGen stock had fallen more than 35 percent as of 12:57pm today, to $5.43 per share. ImmunoGen also stated that the financial guidance it previously announced for fiscal year 2011 was no longer applicable due to the FDA “refuse to file” letter.

“It is a significant disappointment that there will be a delay in the opportunity for T-DM1 to be approved for patients with advanced HER2 positive breast cancer,” Daniel Junius, president and CEO of ImmunoGen, said in the press release. “In the meantime we continue to focus on the development of our robust and expanding pipeline as well as advancing our technology through new partnerships.”

Following today’s FDA decision, Genentech indicated that it will continue its ongoing Phase III trial of T-DM1, as planned, and expects to submit a new application for the treatment in mid-2012, using a different data set than it had submitted for the accelerated approval application this summer.

“We firmly believe in the potential of T-DM1 as a novel HER2-targeted option and remain fully committed to its ongoing development,” said Hal Barron, Genentech executive vice president of product development and chief medical officer, in a company announcement of the news.

On its own, trastuzumab, which nabbed FDA approval as a breast cancer treatment in 1998, generates more than $5 billion in annual sales worldwide.

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