March 1 (Reuters) - Juno Therapeutics Inc on Wednesday said it decided to shut down development of an experimental leukemia treatment from a highly promising new class of immunotherapy following an investigation into toxicity that led to a handful of patient deaths.
The drug, JCAR015, uses a technology known as CAR-T being pursued by other companies as well. CAR-T therapy removes a key component of the immune system called T cells from a patient's blood and re-engineers them to more efficiently attack cancer before returning them to the patient.
JCAR015 was being tested in adults with relapsed acute lymphoblastic leukemia (ALL), a rare and deadly blood cancer.
The company's Phase II program was twice halted last year by the U.S. Food and Drug Administration and remained on hold due to severe neurotoxicity that led to five patient deaths from cerebral edema.
"Juno, in collaboration with partner Celgene, has made a strategic decision to cease development of JCAR015 at this time," Juno said in a statement, adding that it would redirect resources to development of another product for relapsed or refractory ALL.
Juno said its internal investigation identified multiple factors that increased the risk of severe toxic reactions, including "factors related to the product."
The biotechnology company announced the decision in conjunction with release of its fourth quarter financial results.
Other companies developing CAR-T therapies against blood cancers include Kite Pharma Inc and Swiss drugmaker Novartis. Kite this week released highly promising early data for its CAR-T drug against non-Hodgkin lymphoma.
Juno shares fell about 2 percent to $24.64 in extended trading.
(Reporting by Bill Berkrot; Editing by Sandra Maler)