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.
Jin et al. (2026) studied this question.