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Genentech nabs FDA approval for T-DM1 cancer killer

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Roche's ($RHHBY) Genentech picked up FDA approval for its late-stage breast cancer therapy Kadcyla, formerly T-DM1, which uses antibodies to deliver cancer drugs directly to the offending cells.

The treatment combines ImmunoGen's ($IMGN) taxane chemotherapy drug, DM1, with an antibody, trastuzumab, that targets the cell-growth protein HER2. The result: a combo cancer 'smart bomb' that homes in on tumors.

In 20% of breast cancer patients, tumor cells show elevated levels of the HER2 biomarker, allowing Kadcyla to bind to them specifically and safely release the toxic drug. Because it's designed for the later stages of the disease, Kadcyla is intended only for HER2-positive patients that responded to neither trastuzumab nor chemotherapy alone.

Kadcyla isn't the first HER2 drug on the map, with Genentech's pertuzumab and GlaxoSmithKline's ($GSK) lapatinib on the market already. Trastuzumab, the antibody used with Kadcyla, is also used alone as a HER2 drug, but the new compound represents the first time it has been combined with chemotherapy.

The FDA placed the treatment under its priority review program, completing the process within 6 months. The U.S. authorities do this for "drugs that may provide safe and effective therapy when no satisfactory alternative therapy exists, or offer significant improvement compared to marketed products."

Patients in a Phase III clinical trial survived a median of 30.9 months, as opposed to 25.1 months with the alternative treatment. The drug comes with a laundry list of side effects, though, including liver toxicity, heart toxicity and death, the FDA reports. It also comes with a price tag of $9,800 a month, or about $94,000 for 9.5 months of therapy.

Kadcyla is Genentech's fourth advanced-cancer treatment to be approved by the FDA in two years.

- here's the release
- get a HER2 rundown from Genentech

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