Bluebird Bio and partner Celgene reported updated data from their CAR-T cell asset bb2121 targeting B-cell maturation antigen (BCMA), prompting talk of a looming race between anti-BCMA assets. The data were presented at the American Society of Hematology (ASH) conference in Atlanta in December. Bluebird's bb2121 are autologous T cells engineered ex vivo with an anti-BCMA02 CAR lentiviral vector to target tumor necrosis factor receptor superfamily member 17 (BCMA) and 4-1BB as a co-stimulatory domain. The Cambridge, Massachusetts–based biotech reported in its CRB-401 phase 1 dose-escalation trial in relapsing/refractory multiple myeloma an objective response rate of 94% in 18 patients at 40 weeks. These results included 7 confirmed complete responses, 3 unconfirmed complete responses and 16 good partial responses. Safety was good although cytokine release syndrome was seen in 10% of patients, and there was one case of neurotoxicity. Neither the escalation study nor the phase 2 KarMMa trial run by Celgene of Summit, New Jersey, will require BCMA expression as a criterion for enrolment; because the CAR is exquisitely sensitive it can pick up BCMA expression levels far below those detected by assays, according to bluebird's chief medical officer, David Davidson. Bluebird's competitors are Chinese firm Nanjing-based Legend, Novartis, Memorial Sloan Kettering Cancer Center and the US National Cancer Institute, all of which have BCMA-targeting CAR-T cell therapies in development. (Nat. Biotechnol. 35, 590–600, 2017).