Research is expected to continue in an emerging field of cancer treatment despite the deaths of three people in a clinical trial.
Officials at Juno Therapeutics announced on Thursday that the Food and Drug Administration (FDA) had temporarily halted the company's trial of a treatment for adult lymphoblastic leukemia because of the trio of deaths.
They blamed the deaths on a chemotherapy drug that was added to the treatment.
"This is a humbling experience," said Hans Bishop, Juno's chief executive officer, in a conference call. "No doubt it is difficult for the physicians who are looking after these patients and their families. Clearly these therapies are potent, that's why they offer the potential for cures."
Bishop said his Seattle-based company has asked the FDA for permission to continue the trial without the drug in question.
The usual FDA review period is 30 days, but Bishop said the agency has indicated it would process the request quickly.
Bishop said the postponement may derail plans to have this particular treatment available sometime next year, but he still sees "a clear path forward."
Juno executives added they don't think it will affect eight similar programs the company is currently pursuing.
"I don't think this is a huge setback," Dr. Otis Brawley, chief medical officer for the American Cancer Society, told Healthline. "This kind of thing happens. It's unfortunate, but it happens."
New approach to treatment
The drug trial is for a treatment known as chimeric antigen receptor T-cell (CART).
In simple terms, it works by removing t cells from a patient and then re-engineering them to fight cancer.
A chemotherapy cocktail is then given to the patient to attack the cancer but also to kill existing t cells. That's done so when the genetically engineered t cells are reintroduced into the patient, they have room to grow.
Those new t cells are targeted to attack so-called b cells that become malignant in many types of blood cancer.
This particular CART treatment, known as JCAR015, was expected to be Juno's first product on the market, according to a Forbes article.
It is part of a new field of cancer treatment that involves microbiology and immunology.
Juno is in a three-way race with Kite Pharma and Novartis to be the first company to successfully produce this kind of treatment, according to a New York Times story.
What went wrong
The first death in the trials happened in May. The other two occurred last week.
Juno executives said they believe a new chemotherapy drug called fludarabine caused these deaths.
It was added because it allows the re-engineered t cells to take root more quickly.
However, Juno executives said it appears the fludarabine produced some neurological toxicity that caused the deaths.
Fludarabine was given to a handful of the 20 patients enrolled in the phase II study known as ROCKET.
Juno executives said they proposed to the FDA that they continue the CART trial without fludarabine. They plan to use another drug called Cytoxan that has been used in previous CART experiments.
They added they plan to still use fludarabine in other types of CART studies where the drug has not produced any serious side effects.
Death a part of science
Deaths in clinical trials are nothing new.
Also this week an experitmental treatment for a potential leukemia drug was halted after two patient deaths.
At least two other major cancer treatment trials also have been halted earlier this year due to death.
In February, the FDA shut down CTI BioPharma's clinical trial of a drug called pacritinib after patients died from hemorrhage, cardiac failure, and cardiac arrest.
In March, FDA officials also put a stop to a clinical trial being run by Gilead Sciences for a drug called Zydelig after reports of multiple deaths and serious side effects.
Brawley said deaths are not only a part of cancer research trials, but they have also occurred in experiments for medications for hay fever and other conditions.
"We conduct trials because we don't know an answer to something," he said.
He said people also die while being treated with "approved therapies" as well as surgery and other procedures.
Brawley noted that many times people in cancer drug trials have been through other treatments without success.
Indeed, Juno executives said Thursday the people in the CART trials had exhausted all other avenues of treatment.
By David Mills