Activation priming and cytokine polyfunctionality modulate the enhanced functionality of low-affinity CD19 CAR T...

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• Second-generation CD19 chimeric antigen receptor (CAR) T cell therapies have shown promise in treating B cell malignancies.
• Tisagenlecleucel, a high-affinity CAR therapy, has demonstrated clinical efficacy but is associated with toxicities.
• A novel low-affinity CAR, CAT, was developed to potentially improve CAR T cell therapy outcomes.

Purpose of the Study:

• To investigate the molecular mechanisms underlying the enhanced in vitro and in vivo properties of the low-affinity CAT CAR T cells compared to high-affinity CAR T cells.
• To characterize the transcriptomic and proteomic changes in CAT CAR T cells following CD19 stimulation.
• To elucidate the role of antigen-dependent priming in the enhanced functionality of CAT CAR T cells.

Main Methods:

• Comparative analysis of low-affinity (CAT) and high-affinity (FMC63-based) CD19 CAR T cells.
• In vitro stimulation with CD19-expressing cells.
• Transcriptomic analysis using RNA sequencing.
• Proteomic analysis using cytometry by time of flight (CITE-seq).

Main Results:

• CAT CAR T cells exhibited enhanced activation, expansion, cytotoxicity, and antitumor efficacy in preclinical models.
• Phase 1 clinical study showed CAT CAR T cells had an excellent toxicity profile, enhanced in vivo expansion, and long-term persistence.
• Systematic in vitro characterization revealed distinct transcriptomic and protein profiles in CAT CAR T cells post-stimulation.
• CAT CAR T cells demonstrated increased activation and cytokine polyfunctionality compared to FMC63 CAR T cells.
• Enhanced functionality was attributed to antigen-dependent priming by residual CD19-expressing B cells during manufacturing.

Conclusions:

• Low-affinity CD19 CAR T cells (CAT) possess superior functional properties compared to high-affinity CAR T cells.
• The enhanced efficacy and persistence of CAT CAR T cells are linked to specific molecular changes and antigen-dependent priming.
• These findings provide mechanistic insights into the development of next-generation CAR T cell therapies with improved safety and efficacy profiles.