317 Advancing allogeneic CARMAIT cell therapy: isolation, expansion, and engineering for cancer and immune disorders
Year: 2026
Type: conference-abstract
Abstract: Background Unconventional T cells, also referred to as innatelike T cells, including iNKT cells, γδ T cells, and MAIT cells, play a critical role in bridging innate and adaptive immunity. These cell types possess intrinsic tumorhoming capacity, strong infiltration into solid tumors, and the ability to reshape the tumor microenvironment (TME), making them highly attractive modalities for solid tumor immunotherapy. They respond rapidly to diverse stimuli, with MAIT cells uniquely recognizing microbederived vitamin B metabolites presented by MR1. Importantly, because these cells do not induce graftversushost disease (GvHD), CARengineered MAIT cells are particularly well suited for allogeneic, offtheshelf therapeutic applications across both cancer and autoimmune diseases.Methods Using a novel feeder-free proprietary method, Mucosal-Associated Invariant T (MAIT) cells were isolated from human peripheral bloods and stimulated in the G-Rex 6-well plates via MR1-restricted stimulation with 5-amino-6-(D-ribitylamino) uracil (5-A-RU). The expanding cultures were maintained over 14 days with recombinant human IL-7 and IL-15. Cell fold-expansion, viability, and immunophenotypic purity longitudinally monitored via flow cytometry. Following robust expansion, the activated MAIT cells were genetically engineered using a modified lentiviral vector to express either anti-CD19 or anti-GPC3 CAR constructs; conventional CD8 + T cells were engineered in parallel to serve as a control. Finally, the functional profiles of the CAR-MAIT cells were characterized through in vitro co-culture with corresponding tumor targets, where antigen-specific cytotoxicity and IFNγ secretion were assessed to evaluate their therapeutic potency.Results Following the optimized expansion protocol in a small scale, MAIT cultures within 2 weeks currently achieved a >600-fold expansion with over 95% purity based on Vα7.2 staining. The expanded CD19 and GPC3 CARMAIT cell populations exhibited high CAR expression and demonstrated antigenspecific cytotoxicity and inhibition against malignant targets, although their activity was comparatively lesser than that of corresponding conventional CARexpressing CD8 + T cells.Conclusions Our expansion strategy reliably generates clinically relevant quantities of highly pure MAIT cells. These preclinical findings demonstrate that scalable, CARengineered MAIT cells represent a promising allogeneic, offtheshelf platform for the treatment of cancers and immunemediated diseases, supporting their continued advancement toward clinical development.
Language: English
Topic: CAR-T cell therapy research
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,490
OpenAlex ID: W7225155113