Roche/Genentech's breakthrough T-DM1 wins blockbuster OK for breast cancer

Hal Barron, CMO, head of global product development, Roche/Genentech

The FDA today approved T-DM1, a breakthrough antibody drug conjugate from Roche/Genentech widely expected to quickly become a new blockbuster treatment for breast cancer.

Roche ($RHHBY) will market the newly approved drug as Kadcyla. Its partner ImmunoGen ($IMGN) stepped up with the ADC technology and stands to gain a small, single-digit royalty stream from the therapy.

The drug will cost $9,800 a month,or about $94,000 for a 9.5-month course of therapy. Analysts' peak sales projections for this drug have ranged from $2 billion to $5 billion a year.

"Kadcyla is an antibody-drug conjugate representing a completely new way to treat HER2-positive metastatic breast cancer, and it helped people in the EMILIA study live nearly six months longer," said Hal Barron, Roche's chief medical officer and head of global product development.

In early October Roche revealed that the armed antibody delivered a 32% reduction in the risk of death among patients in the pivotal Phase III study when compared to the standard-of-care arm. The median overall survival rate for T-DM1 patients hit an impressive 30.9 months, while patients taking a combination of Tykerb and Xeloda achieved a 25.1-month OS rate.

T-DM1 has helped inspire a whole new wave of antibody-drug conjugates, many of which use technology from either ImmunoGen or Seattle Genetics. Roche/Genentech now has 25 ADCs in their pipeline, including 9 in clinical trials. And dozens more are in or near the clinic at other biopharma companies anxious to match T-DM1's targeting capabilities with a powerful drug payload. 

"Kadcyla delivers the drug to the cancer site to shrink the tumor, slow disease progression and prolong survival," said Dr. Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research. "It is the fourth approved drug that targets the HER2 protein."

Fewer people who received Kadcyla experienced severe side effects compared to those receiving standard therapy (40.8 percent vs. 57.0 percent), the FDA noted. But as expected a boxed warning will apply,noting that the drug can cause liver toxicity, heart toxicity and death. "The drug can also cause severe life-threatening birth defects, and pregnancy status should be verified prior to starting Kadcyla treatment."

"The biggest news in today's press release, given that approval was expected, was that the label allows for use in front-line HER-2 positive metastatic breast cancer," says Cowen's Simos Simeonidis in a note this morning. "This was not a major surprise, since EMILIA included about 12% front-line mBC patients (about 60 1st-line mBC patients in the T-DM1 arm of the EMILIA trial), but it was definitely not a given."

- here's the FDA's release
- get the release from Roche

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