High rates of response that were both deep and durable were seen at the highest dose levels.
Median PFS of approximately one year achieved in heavily pre-treated patients in the active doses of the dose escalation cohort
Consistent response observed for both low and high BCMA expression levels
Adverse events have been manageable across doses
“We are encouraged by the continuing deep and durable responses seen in this study and look forward to the results of our pivotal study, KarMMa, which is currently enrolling,” said
“To see a median PFS of 11.8 months in this heavily pretreated patient population is very encouraging,” said
The open-label phase I CRB-401 study (NCT02658929) is evaluating the preliminary safety and efficacy of bb2121 anti-BCMA CAR T cell therapy in patients with relapsed/refractory multiple myeloma.
Patients in the study were heavily pre-treated, with a median of seven prior myeloma treatment regimens (min, max: 3,14) in the dose escalation cohort (n=21) and eight prior regimens (min, max: 3, 23) in the dose expansion cohort (n=22). More than 90% of patients had received prior treatment with two IMiD® therapies, two proteasome inhibitors, daratumumab and an autologous stem cell transplant.
As of the
Patients received a lymphodepleting conditioning regimen of fludarabine and cyclophosphamide, followed by an infusion of bb2121 anti-BCMA CAR T cells. The CAR T cells were produced from each patient’s own blood cells, which were modified using a proprietary lentiviral vector encoding the anti-BCMA CAR.
Response outcomes in efficacy evaluable patients* in the study were as follows:
50 x 106 (n=3),
median follow-up 84
150 x 106 (n=14),
median follow-up 87
>150 x 106 (n=22),
median follow-up 194
days (46, 556)
Very good partial
Median duration of
|1.9 months||Not estimable||10.8 months|
*Patients with ≥2 months of response data or PD/death within <2 months
Responses were dose-related and observed for both low and high BCMA expression levels. In patients treated with 450 x 106 CAR+ T cells whose myeloma cells expressed low levels of BCMA (0 to 50% of cells BCMA positive), 8 of 8 had a response. In those expressing high BCMA (≥50% BCMA positive), 10 of 11 had a response.
The median progression-free survival (PFS) estimate for patients in the dose-escalation phase treated at active doses (≥150 x 106 CAR+ T cells) was 11.8 months (95% CI 8.8, NE), while patients receiving 50 x 106 CAR+ T cells had a median PFS of 2.7 months (95% CI 1.0, 2.9).
In the dose-escalation and expansion phase of the study, all patients who responded and were evaluable for minimal residual disease (MRD as measured by adaptive next-generation sequencing assay) (n=16) were MRD negative at one or more time points. Additionally, two patients who did not have a response and were evaluated for MRD were MRD positive at month one. The median PFS estimate in MRD negative responders was 17.7 months (95% CI: 5.8, NE).
Among all infused patients (n=43), 63% had cytokine release syndrome (CRS), mostly Grade 1 & 2, with 2 patients experiencing Grade 3 CRS (5%). Nine patients (21%) received tocilizumab, including 4 patients (9%) who also received steroids and the median duration of CRS was 6 days (1,32). For patients receiving 150 x 106 CAR+ T cells (n=18), the rate of CRS was 39% with no grade 3 cases. For patients receiving ≥150 x 106 CAR+ T cells (n=22), the rate of CRS was 82% with 9.1% of patients experiencing grade 3 events. Also among all infused patients, there were 14 patients (33%) who experienced neurotoxicity, with one patient experiencing a grade 3 or higher event. Other frequent Grade 3/4 AEs included cytopenias commonly associated with lymphodepleting chemotherapy such as neutropenia (79%), thrombocytopenia (51%) and anemia (44%), as well as infection (any grade) with a frequency of 61% overall and 23% in the first month. Grade 3 or higher infection occurred with a frequency of 21% overall and 5% in the first month.
“The continuing high, durable response rates and MRD-negative results in this heavily pre-treated population of multiple myeloma patients further illustrates BCMA as a promising target in this incurable disease and bb2121 as an investigational therapy of great potential in patients with relapsed and refractory multiple myeloma with both high and low BCMA expression,” said Dr. Raje., Professor of Medicine at
bb2121 is an investigational compound that is not approved for any use in any country. bb2121 received Breakthrough Therapy Designation from the U.S.
About bluebird bio, Inc.
With its lentiviral-based gene therapies, T cell immunotherapy expertise and gene editing capabilities, bluebird bio has built an integrated product platform with broad potential application to severe genetic diseases and cancer. bluebird bio's gene therapy clinical programs include Lenti-D™ for the treatment of cerebral adrenoleukodystrophy, and LentiGlobin™ for the treatment of transfusion-dependent β-thalassemia, also known as β-thalassemia major, and severe sickle cell disease. bluebird bio's oncology pipeline is built upon the company's leadership in lentiviral gene delivery and T cell engineering, with a focus on developing novel T cell-based immunotherapies, including chimeric antigen receptor (CAR T) and T cell receptor (TCR) therapies. bluebird bio's lead oncology programs, bb2121 and bb21217, are anti-BCMA CAR T programs partnered with
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