In Vitro Tumor Cell Rechallenge For Predictive Evaluation of Chimeric Antigen Receptor T Cell Antitumor Function

Area of Science:

• Immunology
• Cell Therapy
• Cancer Research

Background:

• Chimeric antigen receptor (CAR) T cell therapy is rapidly advancing.
• Current in vitro assays often fail to predict in vivo CAR T cell efficacy due to short co-culture times and high effector-to-target ratios.
• Robust assays are needed to select optimal CAR T cell products for therapeutic success.

Purpose of the Study:

• To develop and validate a novel in vitro co-culture method for assessing CAR T cell recursive killing potential.
• To evaluate CAR T cell function and phenotype over an extended period (7 days) with repeated tumor challenge.
• To differentiate functional and phenotypic characteristics of CD4+ and CD8+ CAR T cells against glioblastoma (GBM).

Main Methods:

• A 7-day in vitro co-culture assay was established with periodic addition of glioblastoma (GBM) tumor cells.
• The assay assessed long-term cytotoxic function and proliferative capacity of CAR T cells.
• T cell activation, exhaustion, and memory phenotypes were profiled alongside functional assessments.

Main Results:

• The assay successfully evaluated CAR T cell recursive killing potential at high tumor cell loads.
• Functional and phenotypic differences between CD4+ and CD8+ CAR T cells against GBM were distinguished.
• Results correlated with differential in vivo antitumor activity observed in orthotopic xenograft models.

Conclusions:

• The developed 7-day co-culture assay provides a facile approach to assess CAR T cell potency.
• This method elucidates functional variations across different CAR T cell products, aiding in the selection of superior candidates.
• The assay's findings support improved preclinical evaluation of CAR T cell therapies.