208 Development of an integrated in vitro and in vivo platform for rapid evaluation of in vivo CAR-T therapies

Background In vivo CAR-T therapy, delivered via lipid nanoparticles (LNPs) or lentiviral vectors (LVVs), enables direct generation of CAR-T cells in situ, bypassing leukapheresis, ex vivo manufacturing, and autologous cell reinfusion. This approach significantly shortens production timelines, reduces costs and improves accessibility. To accelerate and de-risk development, Gempharmatech has established a comprehensive evaluation platform integrating vector functionality, in vitro human T-cell functional assays, and in vivo PK/PD models in humanized mice.Methods The platform includes complementary in vitro and in vivo modules. In vitro assessment quantified vector transduction efficiency, T-cell phenotypic composition, cytotoxicity (across multiple effector-to-target ratios, repeated antigen challenges, and antigen-density-dependent killing), proliferation, cytokine profiling, and off-target toxicity. In vivo studies utilized NCG-MHC-dKO mice reconstituted with human PBMCs and engrafted with Nalm6-luc tumors to evaluate CAR transgene expression, antitumor efficacy, survival, longitudinal cytokine levels, and off-target transduction in non-T immune cell subsets.Results Candidate 1 demonstrated high T-cell transduction efficiency, a balanced CD4/CD8 ratio, potent and durable cytotoxicity, and low secretion of IL-6 and IL-1β, indicating minimal CRS risk with no detectable off-target reactivity in vitro. In the human PBMC-reconstituted NCG-MHC-DKO mouse model bearing Nalm6-luc tumors, Candidate 1 achieved robust CAR expression on T cells, leading to significant tumor growth inhibition and prolonged survival. In vivo cytokine monitoring confirmed only transient, low-level systemic elevations, supporting a favorable safety profile with minimal CRS risk and no off-target transduction in non-T immune cell populations.Conclusions This integrated platform shows strong concordance between in vitro functional and safety readouts and in vivo therapeutic outcomes for in vivo CAR-T candidates. By bridging predictive in vitro biomarkers with authentic in vivo efficacy and safety data, the platform serves as a reliable tool for early screening, risk assessment, and prioritization of in vivo CAR-T therapies, facilitating accelerated clinical translation.