bluebird bio announced that the expansion cohort of the CRB-401 Phase 1 study of bb2121, an anti-BCMA CAR T therapy, has been initiated. The objective of the CRB-401 study is to evaluate the safety and efficacy of bb2121 in patients with relapsed/refractory multiple myeloma and determine a recommended Phase 2 dose. bluebird bio and Celgene are jointly developing bb2121.

"The high response rate and sustained benefit seen with bb2121 in the recent data presented at the ASCO annual meeting in June are particularly gratifying given the limited therapeutic options available for the heavily pretreated patients with relapsed/refractory multiple myeloma participating in our study," said David Davidson, MD, chief medical officer, bluebird bio. "In the expansion stage of the CRB-401 study, we will be treating an additional cohort of patients with a dose range shown to be active in the prior dose escalation stage of the study to gain more experience with the safety, efficacy and durability of response of bb2121."

Patients in the expansion cohort will be treated at a dose range of 150 to 450 x 106 CAR+ T cells and will be required to have prior exposure to a proteasome inhibitor, an immunomodulatory agent and daratumumab.