Juno Therapeutics (NASDAQ: JUNO), a developer of experimental “CAR-T” cancer therapies derived from a patient’s own immune cells, reported this morning that two more patients have died during a trial of its most advanced product, a treatment for adults with acute lymphoblastic leukemia (ALL). The Phase 2 trial, dubbed Rocket, is now on hold for the second time this year.
On a conference call with analysts Wednesday morning, Juno executives did not indicate when the trial would restart. “Adult ALL is proving to be a difficult disease,” CEO Hans Bishop said. “Despite the challenges finding a therapeutic index”— that is, making a drug strong enough to fight disease but not so strong that it poisons patients—“we think we can find a way forward in ALL.”
The cause of death was cerebral edema, or swelling in the brain. It was the same condition that killed three patients earlier this year and forced Juno to stop the trial in July. At the time, the Seattle company blamed the deadly reaction on one of the chemotherapy drugs that Juno was using to “precondition,” or prepare the patients for the Juno product JCAR015. The FDA allowed Juno to restart the trial in short order, however, without the chemo drug, called fludarabine.
The company said its other CAR-T treatments that attack the same target on cancer cells are not on hold. All of Juno’s products use a patient’s own T cells, genetically modify them outside the body to become better cancer killers, then reintroduce them into the patient.
It’s been a rocky year for the cutting-edge cancer therapy. Healthcare giant Novartis (NYSE:NVS) said this summer it would disband its R&D group dedicated to cell and gene therapy. Novartis said it would press on with its top CAR-T programs, but the fate of its other work is unclear.
Juno shares are down nearly 28 percent, to $21.50, in early trading. CAR-T competitor Kite Pharma (NASDAQ: KITE), which is expected to ask the FDA next year to approve its cell therapy for non-Hodgkins lymphoma, saw its shares drop more than five percent to $48.84.
Kite, Juno, and many other CAR-T developers are expected to update their programs at the upcoming annual meeting of the American Society for Hematology. Xconomy has a CAR-T resource that compiles notable trial data here; look for updates with the Juno news and much more next week.