Cell Therapeutics Shares Fall as FDA Says Lymphoma Drug Has “Substantial” Side Effects

2/8/10Follow @xconomy

Seattle-based Cell Therapeutics’ experimental drug for non-Hodgkin’s lymphoma was tested in “substantially fewer” patients than planned in a pivotal clinical trial, and the data that it gathered to support its application shows the treatment has “substantial” toxicity to blood cells and the heart, according to an analysis by FDA staff posted online today. The FDA’s statements sent shares of the company down 38 percent at the opening of today’s trading.

Cell Therapeutics (NASDAQ: CTIC), in its own briefing document, said the clinical data to support the drug is “comprehensive” and that it shrank tumors without causing cumulative heart damage like other drugs in its class.

The documents appeared online in advance of the company’s big appearance before an FDA advisory panel. The meeting starts at 8 am Eastern time/5 am Pacific on Wednesday, February 10. That’s when the Oncologic Drugs Advisory Committee, a panel of cancer drug experts that advises the FDA, will gather in a suburban Washington, DC, hotel. While investors often (correctly) focus on the panel vote as an all-important indicator of whether a new drug will be approved, the FDA itself has the ultimate authority, and isn’t required to follow the committee’s advice.

The FDA’s review of pixantrone is vital for the future of Cell Therapeutics. The company, founded in 1991, has a long and controversial history of ups and downs. It currently has no marketed products, and pixantrone represents its only imminent hope of getting a revenue-generating product on the U.S. market. The drug, a modified form of an anthracycline chemotherapy, was shown to completely eliminate tumors in about 20 percent of patients, compared with 5.7 percent on a standard chemotherapy, based on a single pivotal trial. If the treatment is approved, Cell Therapeutics officials estimate the company can tap into a market of about 10,000 U.S. patients each year who are on at least their third round of treatment for aggressive non-Hodgkin’s lymphoma.

The FDA noted in its analysis that Cell Therapeutics planned to enroll 320 patients in its pivotal trial, known as PIX301 or Extend, but the study was stopped early at an unplanned point because of poor enrollment. The trial ultimately enrolled 140 patients. “A higher level of evidence is usually required” in trials that are stopped short before a final analysis, the FDA staff said.

The FDA report includes details on how many patients died in the PIX301 study. A total of 12 out of 68 (17.6 percent) who got pixantrone died from an adverse event during the trial, while five out of 67 (7.5 percent) in the comparison group died, the FDA said. A total of 25 out of 68 pixantrone patients dropped out of the study because of adverse events, and 21 of the 67 in the control group quit early, the FDA staff said. Most patients dropped out because of bone marrow suppression or toxicity to the heart, the FDA said.

The FDA is asking the panel to respond to two questions. The first question notes that the pivotal trial was halted early after less than half of the planned number of patients enrolled, and given that, the FDA wants to know if the data is strong enough to support approval. The second question is whether the benefits of the treatment outweigh the risks. We’ll find out what the panel says on Wednesday.

Shares of Cell Therapeutics fell 41 cents, or 38 percent, to 65 cents at 9:37 am Eastern time today.

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