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FDA OK’s breast cancer drug created in part by ImmunoGen

Federal regulators approved a highly anticipated breast cancer drug Friday, two and a half years after they sparked patient protests by refusing to grant it a speedy review.

The drug, which will be sold under the brand name Kadcyla, is considered a breakthrough treatment because it deploys a potent toxin that combines with an existing drug, Herceptin, to kill breast cancer cells. It could initially benefit as many as 15,000 patients who have a particularly aggressive form of the disease.

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Kadcyla will be marketed by the Genentech unit of Swiss drug maker Roche AG, which launched Herceptin in the 1990s as one of the first personalized medicines. But key components of Kadcyla were developed by Waltham biotechnology company ImmunoGen Inc., including a proprietary cancer-killing agent and a “linker” that binds the medicine to a type of chemotherapy drug.

“This is certainly good news for a lot of patients who have run out of options,” said Phil McCartin of Hanson, whose wife, Lorraine Heidke-McCartin, has taken the drug for more than two years through a “compassionate use” program that allows some people who didn’t participate in clinical trials to get access to experimental drugs.

Kadcyla was approved for sale to patients with HER2-positive breast cancer — affecting 20 to 25 percent of patients — who have received prior treatment with Herceptin together with chemotherapy. In clinical studies, the treatment was shown to extend the survival of patients with such advanced breast cancer.

It will cost about $9,800 a month, covered largely by insurance for most patients, about double the cost of Herceptin.

Genentech, which will start selling Kadcylas immediately in the United States, has applied for approval to sell it in Europe and Japan.

It also plans to sponsor new clinical trials in an effort to extend the therapy to HER2-positive patients with earlier stages of the disease.

The drug will come with the Food and Drug Administration’s most serious warning label: a so-called boxed warning alerting patients and doctors that it can cause life-threatening liver toxicity, heart toxicity, and birth defects.

Such potential side effects are not unusual in treatments that target aggressive cancers. More common side effects include nausea, fatigue, and muscle or joint pain.

Kadcyla is the first in a promising class of treatments known as antibody-drug conjugates that has been approved by the FDA to treat solid-tumor cancers.

ImmunoGen is developing nine other drugs using its proprietary technology — three by itself and six in partnership with pharmaceutical firms.

“This is the first of what I expect to be many (drug) approvals for this company,” Daniel Junius, chief executive of ImmunoGen, said Friday. “There’s an expectation that this will be a very significant drug over time. It’s a little bit of icing on the cake in terms of validating our technology.”

ImmunoGen will receive a $10.5 million milestone payment and royalties on commercial sales of Kadcyla. The company, founded in 1981, has about 200 employees at its Waltham headquarters and research complex, along with a manufacturing site in Norwood that produces small quantities of Kadcyla and other compounds for use in clinical trials.

After jumping about 4 percent when Kadcyla’s approval was disclosed Friday morning, shares of ImmunoGen closed up 1.8 percent at $14.56, a gain of 26 cents on the Nasdaq exchange.

ImmunoGen’s stock took a 38.5 percent hit on Aug. 27, 2010, when the FDA surprised investors and the breast cancer patient community by rebuffing a bid to fast-track Kadcyla -- then known as T-DM1. FDA officials would not explain their action, citing “commercial confidential information.”

Since then, breast cancer patients and advocates have petitioned the agency to reverse its decision and push the drug review forward, protesting outside the FDA's offices and at the annual convention of the Biotechnology Industry Organization in Boston last year.

The delay hurt thousands of women with advanced cases of HER2-positive breast cancer, said McCartin, co-founder with his wife of the activist group Our HER2 Cancer Struggle.

“This drug is arguably the best breast cancer drug since Herceptin,” McCartin said. “But the FDA ignored the top breast cancer researchers in the country and they ignored the patients who knew this was a special drug that deserved accelerated approval.”

Ultimately, however, the FDA said it approved Kadcyla under a separate “priority review program” that hastens the regulatory process when drugs offer significant improvement compared with other products on the market or when there are no satisfactory alternative treatments available.

FDA spokeswoman Stephanie Yao would not comment specifically Friday on why the agency’s approval of Kadcyla took as long as it did.

“The agency strives to work quickly and closely with sponsors to approve innovative new therapies to treat serious diseases, and we are committed to approving drugs needed by patients who have late-stage breast cancer,” Yao said.

Securities analysts have estimated Kadcyla could ring up annual sales of nearly $2 billion as its use expands to more patients in more countries. ImmunoGen’s share would amount to 3 to 5 percent under the royalty agreement with Genentech. The 5 percent level would be triggered when sales top $700 million in either the US or the rest of the world.

“We don’t speculate on sales, but we’re very excited about the approval,” said Susan Willson, a spokeswoman at Genentech’s headquarters in South San Francisco, Calif. “HER2 breast cancer is a very aggressive disease where new treatments are badly needed. Our hope is that Kadcyla will have a big impact for people with this disease.”

Robert Weisman can be reached at weisman@
globe.com
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