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Juno Therapeutics lab
Inside Juno Therapeutics’ lab, employees work with a patient’s genetically engineered T-cells and prepare them for infusion. (Credit: Juno Therapeutics)

Seattle-based Juno Therapeutics says it’s resuming a clinical trial of its immunotherapy treatment, a week after the Food and Drug Administration ordered a hold due to the deaths of three patients.

The FDA lifted its hold on the Phase II clinical trial for Juno’s first product, known as JCAR015, after the company removed a chemotherapy drug known as fludarabine from the treatment protocol. The deaths resulted from cerebral edema, or brain swelling, which was thought to have been caused by a toxic reaction to a drug combination including fludarabine.

Fludarabine was added to the pre-conditioning treatment regimen only recently. A different drug, known as cytoxan or cyclophosphamide, will continue to be used.

Now that the hold has been lifted, patients can once again be enrolled in the trial.

Juno’s stock dropped by 27 percent last week when the hold was announced, and rebounded on Wednesday after the resumption was announced. The stock drifted downward during today’s trading, however.

JCAR015 is one of a new class of treatments known as chimeric antigen receptor T-cell therapy, or CAR-T. Such treatments enlist the body’s own immune system to attack cancer cells. The JCAR015 treatment targets adult leukemia. The Phase I clinical trial showed encouraging results, although it also suggested there was a risk of neurotoxicity.

Before the deaths were reported, Juno said JCAR015 could win regulatory approval as early as 2017. Now the company is reassessing its timeline for testing the treatment. “We’ll get a clear sense of that over the next couple of weeks,” Juno spokesman Christopher Williams told GeekWire.

Juno says its other clinical trials weren’t affected by the FDA’s action.

Williams said the company’s workforce has been growing at a rapid clip, from 307 employees at the end of 2015 to about 450 today. Most of those new employees are involved in research.

So is this a one-time surge, or the start of a rapid upswing? “I think we’ll continue to see growth,” Williams said. “I can’t comment on how rapid that growth will be.”

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