Seattle Genetics' Experimental Drug Shrinks Hodgkin's Tumors, Study Shows

Seattle Genetics Inc. and Takeda Pharmaceutical Co.’s experimental drug wiped out tumors in one- third of patients with hard-to-treat Hodgkin’s lymphoma and reduced the cancer by half in another 40 percent, a study found.

Overall, 94 percent of 102 patients had their tumors shrink by at least a quarter, an “unheard-of” level of improvement in people who had failed other treatments, said study leader Robert Chen, an assistant professor at City of Hope, a nonprofit cancer center in Duarte, California. He presented the study today at the American Society of Hematology meeting in Orlando, Florida.

Results for the drug, SGN-35, drew mixed responses from analysts about the therapy’s potential for hard-to-treat Hodgkin’s lymphoma and pushed shares down as much as 6.6 percent. While the data should support approval, the drug may have a “limited market opportunity,” George Farmer, an analyst with Canaccord Genuity in New York, said today in a note to investors.

“We believe shares are overvalued,” Farmer wrote. The 34 percent complete response rate fell short of what was hoped for by some investors, he said.

Seattle Genetics fell 64 cents, or 4 percent, to $15.23 at 4 p.m. New York time in Nasdaq Stock Market composite trading.

‘Widely Adopted’

“Some investors are concerned that the size of the market for SGN-35 is small,” said Jason Kantor, an analyst with RBC Capital Markets in San Francisco, in an e-mail. “I believe that a targeted agent with this level of efficacy and tolerability will be widely adopted in Hodgkin’s lymphoma and anaplastic large cell lymphoma, and there are other market opportunities.”

Seattle Genetics may have annual worldwide revenue from SGN-35 of $425 million in 2015, Kantor said.

The treatment uses an antibody to target and bind with a protein on the surface of lymphoma cells, then blasts them with a cancer-killing chemical. This keeps the drug out of the bloodstream and away from healthy tissue, avoiding the side effects of standard chemotherapy, Chen said.

The drug’s effectiveness “met our expectations,” said Bret Holley, an analyst for Oppenheimer & Co., in an analyst note released today. The low rate of side effects “likely exceeded expectations,” Holley wrote.

Earlier ‘Hint’

“We had a hint this was going to be an effective agent from an earlier trial but we had no idea it was going to be this good,” said Chen, who also works as a consultant for Seattle Genetics. “Patients tolerated this drug very well.”

About 8,500 people in the U.S. are diagnosed every year with Hodgkin’s lymphoma and 1,300 of them die, according to the National Cancer Institute. The disease attacks the lymphatic system, part of the body’s disease-fighting mechanism, and can lead to enlargement of the spleen, the lymph nodes and other tissues. It also causes night sweats, fever, weight loss and fatigue in about 40 percent of patients, Chen said.

Patients tend to develop lymphoma either as young adults in their 20s or 30s or when they’re in their 60s. While the disease can be cured in about 70 percent of patients, Chen said, his study tested the drug in people who relapsed or didn’t respond to treatment.

The patients were mostly young, with a median age of 31, and had advanced cases of the disease, Chen said. All had been treated with chemotherapy and stem cell transplants drawn from their own blood.

New Option

“When patients have failed multiple lines of treatment, as these patients had, it’s usually a very difficult discussion,” Chen said. “It’s tough for the patients and for us because there’s no standard therapy. The only options are palliative care or clinical trials.”

Seattle Genetics plans to apply to the Food and Drug Administration for approval of the medicine in the first half of 2011, said chief executive officer Clay Siegall. SGN-35 would be the company’s first marketed product.

The combination drug works like a guided missile, using an antibody to spot a protein called CD-30 found only on the surface of lymphoma cells. When it finds them, it delivers the anticancer agent, which disrupts cell division to destroy the cancer.

In the study, patients were given SGN-35 by infusion every three weeks for up to 16 cycles. Each infusion takes about a half an hour and can be administered by a nurse, Chen said.

Some patients responded almost immediately, he said. Several “had really enlarged lymph nodes and you could see them shrink in a week,” he said.

Side Effects

Patients maintained the reduction of their tumors for a median of 29 weeks, according to independent reviewers, Chen said. The most common serious side effects were a lowering of white blood cells in 20 percent of patients, low blood platelet counts and nerve pain in 8 percent and anemia in 6 percent, Seattle Genetics said in a statement.

Seattle Genetics has exclusive North American marketing rights and Osaka, Japan-based Takeda can sell the drug everywhere else, the companies said in December 2009 when they announced the partnership. The companies share development costs equally, except in Japan, where Takeda is solely responsible.

To contact the reporter on this story: Rob Waters in San Francisco at rwaters5@bloomberg.net.

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net.

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