Pfizer Inc. (PFE)’s blood-cancer drug Mylotarg, pulled from the market last year after it was linked to deaths, helped a different group of patients, a study found.
Patients newly diagnosed with acute myeloid leukemia who received Mylotarg with chemotherapy lived for 25 months after treatment, compared with 15 months for those given chemotherapy alone, according to the study released today at the American Society of Hematology meeting in San Diego. Mylotarg had previously been used in patients ages 60 and older only after their cancer had returned.
Pfizer, the world’s biggest drugmaker, will talk with U.S. regulators about whether the medicine may return to the market, said Mace Rothenberg, senior vice president of clinical development and medical affairs for the New York-based company’s oncology unit.
“We are working closely with investigators to better understand the findings from this study,” Rothenberg said in a telephone interview. The next step would be “taking these data forward as a potential new submission, working with regulators, if we choose to go that path,” he said.
The study results may presage new life for what was an $83 million product in 2009, according to Evaluate Pharma.
Pfizer pulled the drug in June 2010 after 10 years on the market. The Food and Drug Administration requested the company stop selling the therapy after a clinical trial showed it didn’t help patients and was tied to deaths from liver complications.
Mylotarg was approved in 2000 under an expedited review process, which requires companies to conduct follow-up studies. One such trial that began in 2004 was stopped early after patients died and others didn’t appear to benefit. Pfizer obtained Mylotarg in 2009 when it bought Wyeth.
The drug originally was approved for patients 60 and older who had a relapse of acute myeloid leukemia, a blood cancer that begins growing in the bone marrow. The disease will be diagnosed in 13,000 people in the U.S. this year and has a five-year survival rate of 23 percent, according to the National Institutes of Health.
Mylotarg was the first therapy approved to treat patients whose cancer had returned and was the first drug to be withdrawn after winning approval under the U.S. Food and Drug Administration’s accelerated review program.
The study released today involved 280 patients ages 50 to 70 who were first diagnosed with the disease. The group was treated with chemotherapy and some patients also received Mylotarg.
Pfizers’s drug was given to patients over a week, in 3 milligram increments, said Sylvie Castaigne, the principal investigator. “We used a small dose, and repeated the dose a short intervals,” said Castaigne, a professor in the department of hematology at Hôpital de Versailles in Versailles, France.
Next “will be to test the drug in younger patients, because we know that younger patients respond better than older patients to chemotherapy,” Castaigne said in a telephone interview from San Francisco. Researchers also examine whether they can get similar results with a lower dose. “We are right at the limit of toxicity now,” she said.
The drug must be resubmitted to the FDA with the new data before it could return to the U.S. market, Rothenberg said.
“Our knowledge is always moving forward, and sometimes we may not always have the best insights of how best to use the drug when it first arrives,” he said. “In this case, it was right on that margin, and it fell back. Now it’s just a question of finding that right dose in the right patients, and clearly demonstrating a benefit.”
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