Celgene, bluebird bio report high response rates in early-stage study of CAR-T therapy bb2121 in myeloma

Celgene and partner bluebird bio announced Sunday updated results from an early-stage trial of bb2121, with the experimental anti-BCMA CAR T cell therapy demonstrating an overall response rate (ORR) of 86 percent in 21 patients with late-stage relapsed/refractory multiple myeloma. In addition, among 18 patients who received higher, active doses of infused CAR T cells, the ORR increased to 94 percent, with 10 patients achieving a complete response.

"We are excited about the early results in a patient population with very advanced myeloma for whom previous therapies have failed," commented senior study author James Kochenderfer. "We have patients who have a sustained response and have been able to go for over a year with no additional myeloma therapy and tolerable adverse effects," Kochenderfer added.

In June, Celgene and bluebird bio announced updated results from the Phase I study showing that all 15 evaluable patients with relapsed/refractory multiple myeloma who received an active dose of bb2121 achieved an objective response. Data, which were presented at the ASCO annual meeting, revealed that among patients assigned to active treatment, 27 percent achieved complete responses, while 47 percent achieved a very good partial response.

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The companies noted that as of the October 2 data cut-off, 21 patients had been enrolled in the trial and dosed in four dose cohorts. Patients in the study were heavily pre-treated, with a median of seven prior therapies. Celgene and bluebird bio indicated that patients received a conditioning regimen of cyclophosphamide and fludarabine, followed by an infusion of bb2121, which is produced from each patient's own blood cells, modified using a lentiviral vector encoding the anti-BCMA CAR.

Results detailed at ASH showed that nine of 10 patients who were evaluable for MRD status were found to be MRD-negative. The drugmakers added that median progression-free survival (PFS) has not been reached in the active dose cohorts, with PFS at 6 months and 9 months of 81 percent and 71 percent, respectively. Celgene and bluebird bio noted that three patients who initially responded to bb2121 subsequently experienced disease progression.

According to the companies, 71 percent of patients had cytokine release syndrome (CRS), mostly grade 1 and 2, with two patients experiencing grade 3 CRS. Lead study investigator Jesus Berdeja said bb2121 was very well tolerated for a CAR-T product, adding that the response rates are "unheard of, something that we haven't seen with any drugs approved for myeloma in this type of population."

Celgene and bluebird bio entered into an agreement in 2013 to jointly develop CAR-T therapies to target and destroy cancer cells. The partnership was amended in 2015 to focus on the development of product candidates targeting BCMA, with bluebird bio regaining rights to CAR-T products outside BCMA.

For related analysis, see ViewPoints: bluebird puts on a sheen for investors ahead of vital ASH readouts.

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