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FDA Approves T-DM1 as Kadcyla for Breast Cancer

By Randy Osborne
Staff Writer

Beating its next-Tuesday decision deadline, the FDA cleared for marketing the antibody-drug conjugate (ADC) Kadcyla (ado-trastuzumab emtansine or T-DM1) for HER2-positive metastatic breast cancer (mBC) previously treated with Herceptin (trastuzumab) and a taxane chemotherapy. Kadcyla – developed like Herceptin, by Genentech, part of Roche AG – is the fourth advanced-cancer drug from Genentech to win FDA approval for people with advanced cancers within the past two years, and the first-ever ADC to gain the go-ahead in the U.S. for HER2-positive mBC.

Genentech expects to launch the drug within two weeks.

In line for a $10.5 million milestone payment as a result of the FDA’s action, plus royalties, is partner ImmunoGen Inc., which came up with the idea of pairing its DM1 maytansinoid cell-killing agent to Genentech’s blockbuster Herceptin. In 2000, Genentech licensed from ImmunoGen exclusive rights to use the company’s maytansinoid TAP technology, and by 2006, T-DM1 (as the compound long was known) had reached the clinic. Various Phase III trials are under way or planned to test Kadcyla in other HER2-positive breast cancer indications.

Kadcyla wowed attendees of the European Society of Medical Oncology in Vienna, Austria, last fall, when promise over the summer – when some data were unveiled at the American Society of Clinical Oncology – came to even more satisfying fruition. Results from a trial in 991 women showed they lived a median of 30.9 months, compared to 25.1 months on Tykerb (lapatinib, GlaxoSmithKline) with Xeloda (capecitabine, Roche). The Kadcyla group showed fewer severe side effects, too: 40.8 percent vs. 57.0 percent. The biologics license application was submitted last August. (See BioWorld Today, Oct. 2, 2012, and Aug. 28, 2012.)

With the survival advantage comes a significant price hike. A course of Kadcyla will cost $9,800, which means the 9.6-month stint of therapy adds up to about $94,000, as compared to the Tykerb/Xeloda tag of about $10,460 per month. Genentech said its patient assistance programs will help people who might not be able to afford the drug. Those without health insurance, or who have reached the lifetime limit set by their provider, could get Kadcyla free.

Jefferies analyst Thomas Wei, in a research report earlier this month, anticipated the pricing benefit for ImmunoGen’s shareholders, and pinned the stock with a “buy” rating. “We note many recently launched cancer drugs (including many with no overall survival benefit) have been priced at a premium to the $60,000/per patient that we have assumed, and believe there could be considerable upside on the high end,” Wei wrote. “Furthermore, we may have been conservative in our assumptions for first-line penetration of T-DM1.”

ImmunoGen’s stock (NASDAQ:IMGN) was trading Friday morning at $14.77, up 47 cents. See Monday's BioWorld Today for More on This Story.