Abstract Background: Humanized mouse models are critical for evaluating in vivo CAR-T therapies, but their utility is limited by rapid onset Graft-versus-Host Disease (GVHD). We employed a novel NCG-MHC-dKO model to mitigate GVHD, enabling prolonged assessment of anti-tumor efficacy for different in vivo CAR-T modalities. Methods: The NCG-MHC-dKO model was reconstituted with human PBMCs, confirming delayed GVHD. Mice bearing Nalm-6 tumors were treated with a single dose of either a lentiviral vector or an LNP formulation delivering a CD19-targeting CAR. Tumor growth was monitored via bioluminescence imaging. Results: The PBMC-NCG-MHC-dKO model demonstrated a significantly extended observation window due to postponed GVHD. In this model, both lentiviral and LNP-based in vivo CAR-T therapies potently suppressed Nalm-6 tumor growth. Functional CAR-T cells generated in vivo were detected and expanded in treated mice. Conclusion: The PBMC-reconstituted NCG-MHC-dKO model provides a robust and durable platform for in vivo CAR-T evaluation by overcoming early GVHD. We successfully validated its utility for both lentiviral and LNP delivery platforms, demonstrating significant and comparable anti-tumor efficacy. Citation Format: Hongyan Sun, Xiaoliu Yang, Shiying Guo, Yujing Zhang, Huixin Yang, Xiang Gao. Robust in vivo CAR-T efficacy evaluation in a PBMC-reconstituted NCG-MHC-dKO model with delayed GVHD abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2166.
Sun et al. (Fri,) studied this question.