Abstract 6122: Off-the-shelf BCMA/GPRC5D dual targeted CAR-NK cell therapy combined with Daratumumab in treating multiple myeloma

Abstract B cell maturation antigen (BCMA), and Orphan G protein-coupled receptor, class C group 5-member D (GPRC5D) targeted chimeric antigen receptor (CAR) T cell therapies have been successful as treatment options for refractory/relapse multiple myeloma (RRMM) patients. BCMA/GPRC5D dual-targeting CAR-T to address antigen loss is also being explored. However, CAR-T cell manufacturing and potential toxicities have prevented broad patient access. Natural killer (NK) cells have demonstrated an allogeneic cell therapy modality showing promising antitumor efficacy while exhibiting a more favorable safety profile in clinical testing. We have previously shown the successful engineering of IL15 armored BCMA/GPRC5D dual targeted CAR-NK cell therapy for treating MM (AACR 2023; clinical candidate SNC112). To target MM in a broader and more comprehensive manner, SNC112 were tested in combination with Daratumumab (DARA). To improve antibody-dependent cellular cytotoxicity (ADCC) response, high-affinity variants of CD16 (158V/V polymorphism) peripheral blood donors were selected for manufacturing. To avoid self-inflicted NK-cell-mediated fratricide, the stimulation and expansion protocols were optimized to limit CD38 expression on NK cells without inducing gene editing into scaled manufacturing process. In vitro short-term and serial killing assays were performed against MM cell lines to verify CAR functions and evaluate ADCC responses between different manufacturing protocols. The NK purity and surface markers expression were characterized by flow cytometry. The combinational antitumor efficacy was assessed in vivo in multiple xenograft models using NPG mice. SNC112 induced near 100% in vitro specific cytotoxicity using luciferase-label MM cell lines while non-transduced NK showed no cytotoxicity. SNC112 displayed dual-targeted repetitive tumor-killing potential with a RTCA based serial killing assay using CHOK1-BCMA and/or CHOK1-GPRC5D cells. SNC112 manufactured with optimized protocols showed significantly decrease of CD 38 expression (10% vs 80%), improved freeze/thaw recovery, prolonged in vivo persistence, and enhanced ADCC responses. In a CD38-low expression animal model, a sub-optimal dose of SNC112 combined with DARA displayed synergistic increase in tumor targeting through various tumor associated antigens, whereas SNC112 solo and DARA solo resulted in no significant antitumor activity. In a CD38-high expression animal model, both of SNC112+DARA and Non-transduced NK+DARA combos were able to achieve complete clearance of tumor cells. However, only SNC112+DARA could achieve sustained tumor control against re-challenge tumor cells. Studies presented demonstrate the potential of SNC112+DARA combo as a highly effective multi-antigen targeting and a cost-effective off-the-shelf cell therapy in treating MM. Citation Format: Chao Wang, Tingting Liu, Qin Wang, Yanxue Gong, Fanxiang Gao, Feng Zhou, Zhuoxiao Cao. Off-the-shelf BCMA/GPRC5D dual targeted CAR-NK cell therapy combined with Daratumumab in treating multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6122.