Bluebird bio (
BLUE +3%) and collaboration partner Bristol-Myers Squibb (
BMY +0.5%) (via its acquisition of Celgene) announce
updated results from a two-part open-label Phase 1 clinical trial,
CRB-402, evaluating BCMA-targeted CAR T candidate bb21217 in heavily pretreated patients with relapsed/refractory multiple myeloma (MM), a population with a poor prognosis. The data were presented at ASH in Orlando.
The dose-escalation portion (three dose levels) is finished. The dose-expansion phase is in process. Final enrollment should be 74 subjects.
12 patients in the 150 x 106 CAR+ T cells arm (the lowest dose) were evaluable. Mean follow-up was 17.6 months. 83% (n=10/12) showed clinical response, including four complete responders and six with very good partial responses. Median duration of response was 11.1 months.
As of the data cutoff, follow-up was still early in the other dose arms (300 x 106 CAR+ T cells and 450 x 106 CAR+ T cells) but no confirmed responders have progressed. The response rate in the 300 group was 43% (n=6/14), none complete, and 57% (n=4/7) in the 450 group with one complete responder. Median follow-up periods were 4.0 months and 3.3 months, respectively.
On the safety front, the most frequent serious/life-threatening adverse events in 38 treated patients were neutropenia (82%), leukopenia (55%), thrombocytopenia (55%), anemia (50%), lymphopenia (34%), hypophosphatemia (21%), hyponatremia (13%) and febrile neutropenia (11%). Seven patients experienced serious/life-threatening infections.
66% (n=25/38) developed bb21217-related cytokine release syndrome (CRS), most mild or moderate. There was one case of serious CRS and one death (in the 450 arm after 15 days of follow-up). 24% (n=9/38) developed neurotoxicity, two serious and one life-threatening (encephalopathy).
The estimated completion date is January 2025.
#ASH19