SEATTLE, July 8 (UPI) -- A clinical trial for a new immunotherapy drug for leukemia was halted by the U.S. Food and Drug Administration after two patients died last week, the company developing the drug reported this week.
Juno Therapeutics stopped its phase 2 "ROCKET" trial for JCAR015 under instruction from the FDA after the two recent deaths, which follow another earlier this year -- though the company hopes to restart the trial after making changes to how the drug is delivered.
JCAR015, a treatment for adult patients with relapsed or refractory B cell acute lymphoblastic leukemia, is part of a class of drugs opening up new treatment avenues for difficult cancers by retraining the immune system to fight cancer itself.
Immunotherapy drugs involve removing T cells from a patient's body, reprogramming them to hunt cancerous cells and returning them to the patient.
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The three patients who died during the trial all had cerebral edema, or brain swelling caused by excess fluid, which Hans Bishop, chief executive officer of Juno, said in a teleconference with reporters was likely caused by pre-treatment with fludarabine.
Before patients are treated with JCAR015, they receive a dose of chemotherapy -- in this case fludarabine -- to kill off existing immune cells in the body and allow the re-engineered cancer-killing cells to be more effective.
After the first patient died in May, neither the company nor the agency understood what caused the cerebral edema, though with two further deaths, the FDA placed the trial on clinical hold.
While fludarabine was not used in the phase 1 trial for JCAR015, meant to test the treatment's safety, the company added it to the drug regimen because it improved patient outcome in other immunotherapy trials without additional side effects. In this case, Juno executives think the chemotherapy interacted poorly with JCAR015.
Juno has proposed to the FDA that it continue the trial without fludarabine, instead only using the drug cyclophosphamide, as it did in the safety trial.
The agency has requested, and Juno has already submitted, a revised patient informed consent form, a revised investigator brochure and a revised trial protocol before possibly allowing it to continue enrolling patients.
