A novel triple-knockout allogeneic BCMA CAR T cell therapy (CT0590) in multiple myeloma: preclinical and phase I study

Host-versus-graft reaction (HvGR) is a major challenge in allogeneic chimeric antigen receptor (CAR) T cell therapy. To counter host natural killer (NK) cell attacks, we armored allogeneic, human leukocyte antigen (HLA)-I deficient, B-cell maturation antigen (BCMA)-targeting CAR T cells with an NKG2A CAR. In vitro and animal studies demonstrated that allogeneic CAR-NKG2A T cells effectively resisted host NK cell-mediated killing. BCMA and NKG2A dual-targeting allogeneic CAR T cells (CT0590) resisted killing by NK cells and showed robust antitumor activity in preclinical in vivo models. On the basis of these data, a first-in-human study (NCT05066022) enrolled five patients (four with relapsed and refractory multiple myeloma [RRMM] and one with primary plasma cell leukemia [pPCL]). CT0590 was well-tolerated and caused no dose-limiting toxicities, treatment-related death, or graft-versus-host disease. Three patients achieved confirmed responses, including two with stringent complete response (sCR). Notably, sCR in the patient with RRMM was still ongoing (duration of response > 23 months) at the time of data cutoff, and sCR in the patient with pPCL lasted for 20 months. Both patients showed robust expansion of universal CAR (uCAR) T cells (Cmax > 280,000 copies/µg gDNA) and higher baseline NKG2A expression on NK cells than nonresponders. These results suggest that CAR-NKG2A technology may overcome HvGR, especially in patients with elevated NKG2A expression on NK cells. Further studies of CT0590 in RRMM and pPCL are warranted.