Cell Therapeutics said late Friday it has halted enrollment in its most important clinical trial because of premature deaths among patients taking its experimental cancer drug.
James Bianco, chief executive of the Seattle company, said the deaths do not appear related to any safety problems with its drug, Xyotax.
In an interview, Bianco would not say how many patients enrolled have died among the 200 women with lung cancer. But he acknowledged there were more deaths in the group receiving Xyotax than another receiving a standard chemotherapy drug. Further analysis is needed to sort out the reasons, he said.
Bianco said most of the deaths have been attributed to disease progression — meaning the advancement of the patient's cancer. The study's patients have advanced lung cancer, with a life expectancy of 8 to 10 weeks.
The company said it expects results from the study to be delayed by at least six months while the data is studied. That could have a financial impact on the company, which has regularly run low on cash.
Cell Therapeutics said it made the decision to halt enrollment voluntarily after getting advice from doctors on the study and an independent safety-monitoring committee.
The study, known as Pioneer, has the unusual feature of being limited exclusively to women with lung cancer. It began enrollment at 170 medical centers around the world in April, and is designed for up to 600 patients.
The company is testing whether Xyotax can prolong patients' lives. Xyotax uses a common chemotherapy agent and modifies it with a polymer intended to make it more tolerable.
Last year, the drug failed to show a survival benefit in three major lung-cancer trials, but the company thought it saw some positive signs in women.
Women who have already enrolled in the study will be able to continue receiving treatment, the company said.
Bianco said the company expects to revise the study when it resumes, to focus on women with normal estrogen levels. He said earlier that Xyotax studies had found a better effect in such women.
Also, said Bianco, "Some of the women in the trial are entering when they are sicker than they probably should be."
The halted trial isn't the first in the company's history. In October 2003, it halted a Xyotax trial in lung cancer and reduced the dose, after "a handful" of patients suffered premature deaths when their infection-fighting white blood cells were wiped out.
This time, Bianco said, his company is using a lower dose from the start, and it thinks the premature deaths are not related to drug toxicity.
Bianco said the delay will not affect the company's newly signed partnership with Swiss drug giant Novartis.
The news was released after markets had closed. Cell Therapeutics shares ended trading unchanged at $1.66.