By Saumya Joseph

(Reuters) – Bluebird bio Inc and Bristol-Myers Squibb Co on Monday reported encouraging initial data from an ongoing early-stage study testing their experimental therapy for multiple myeloma in patients who did not respond to prior treatments.

The lowest dose of the therapy, bb21217, had a median duration of response of 11.1 months and an overall response rate of 83% in heavily pre-treated patients with at least three prior lines of therapy, according to data presented at the American Society of Hematology Conference.

Bb21217 belongs to a class of drugs called CAR-T therapies that involve drawing white blood cells from a patient, processing them to target cancer cells, and infusing them back into the patient.

Typically with CAR-T cell therapy, after around six months of receiving the treatment, the presence of CAR-T cells available to fight the tumor cells diminishes to levels that are no longer measurable, bluebird Chief Medical Officer Dave Davidson told Reuters.

With bb21217, the companies are looking to prolong the persistence of CAR-T cells in the body, which could translate into more durable clinical responses following treatment, he added.

Bluebird and Bristol-Myers on Friday reported positive results from a mid-stage trial for another CAR-T therapy, Ide-cel, for multiple myeloma. [nL4N28G3QL]

The safety profile of bb21217, which targets a protein linked to multiple myeloma known as BCMA, was consistent with the known toxicities of CAR-T therapies, regardless of dosage, the companies said.

(Reporting by Saumya Sibi Joseph in Bengaluru; Editing by Shinjini Ganguli)