A trial of Juno Therapeutics’s genetically engineered cancer therapy, known as JCAR015, was put on hold by U.S. regulators after three leukemia patients died from side effects, the company said on Thursday.
Shares of Juno (JUNO) fell 30% to $28.50 in after-hours trading on the Nasdaq.
The U.S. Food and Drug Administration halted the trial after a patient died in May and two more died last week, Juno Chief Executive Officer Hans Bishop told reporters on a conference call. All three were in their 20s, and the deaths were linked to swelling in the brain, the company said.
JCAR015 is an experimental chimeric antigen receptor T-Cell, or CAR-T, therapy, requiring a complicated process of extracting immune system T cells from an individual patient, altering their DNA to sharpen their ability to spot and kill cancer cells, and infusing them back into the same patient.
Seattle-based Juno said the deaths occurred after the chemotherapy agent fludarabine was added to the trial program. The company said it has proposed to the U.S. Food and Drug Administration that the trial be continued using JCAR015 with just cyclophosphamide as a “pre-conditioning agent.”
Patients receiving CAR-T therapies typically receive doses of chemotherapy beforehand, meant to make the tumor more vulnerable to the CAR-T cell.
In the results so far of some early-stage clinical trials, CAR-T therapies eliminated all trace of leukemia and lymphoma in 40% to 90% of patients who had run out of other options. But the experimental medicines can cause cytokine release syndrome, a dangerous buildup of toxic debris from killed tumor cells, and damage to healthy tissue.
Juno said the FDA asked the company to submit a revised patient consent form, investigator brochure, trial protocol, and a copy of the presentation made to the agency on Wednesday. Juno said it plans to submit the requested information this week.
CEO Bishop said the company will have more clarity in the next few weeks on when the results of the halted trial can be expected. Juno had planned to seek its first drug approval—JCAR015 for adult patients with relapsed acute lymphoblastic leukemia—by early 2017. The company is testing other CAR-T cells for pediatric ALL, non-Hodgkins lymphoma and other cancers.
Bishop said Juno’s other products, including CAR-T therapy JCAR017, are not affected by the trial hold.
Other companies developing CAR-T therapies include Kite Pharma (KITE), Bluebird Bio (BLUE), Celgene (CELG) and Novartis AG (NVS).
In after hours trading, shares of Kite were down about 9%, Bluebird shares fell 3.5% and Celgene fell 1.4%. Novartis shares were flat.
The CAR-T technique is being tested against a range of different cancer types, but first in blood cancers.
Cowen & Co analyst Eric Schmidt said he does not expect Juno’s disruption to affect Kite, which uses less intensive chemotherapy regimens in its trials. “We continue to expect positive data from the pivotal ZUMA-1 trial in DLBCL (diffuse large B-cell lymphoma) this fall,” he said, referring to Kite’s study.