Multiple cancer-specific antigens are targeted by a chimeric antigen receptor on a single cancer cell

Area of Science:

• Immunology
• Oncology
• Glycobiology

Background:

• Adoptive T cell transfer using chimeric antigen receptor (CAR) T cells shows promise in cancer therapy.
• CAR T cells engineered with antibodies targeting specific cancer antigens can eliminate tumors.
• Understanding CAR T cell specificity and mechanisms of tumor escape is crucial for improving efficacy.

Purpose of the Study:

• To determine the specificity of T cells transduced with a CAR derived from an antibody (237Ab) targeting murine Tn-glycosylated podoplanin (Tn-PDPN).
• To elucidate the mechanism behind the observed absence of tumor relapse in patients treated with these CAR T cells.

Main Methods:

• Generation of CAR T (CART) cells using the 237Ab specific for Tn-PDPN.
• Assessment of 237CART cell lysis against various human and murine cancer cell lines.
• Analysis of Tn glycosylation and peptide backbone recognition requirements for 237CART cell activation.

Main Results:

• 237CART cells demonstrated broad reactivity against multiple human and murine cancers, exceeding the specificity predicted by 237Ab binding alone.
• Cancer-specific recognition was maintained, as it depended on Tn glycosylation resulting from COSMC mutations absent in normal tissues.
• While Tn glycosylation was necessary, it was insufficient for activation; peptide backbone recognition was also required, with tolerance for substitutions in the recognized motif.

Conclusions:

• A novel principle of cancer targeting is demonstrated, where simultaneous recognition of multiple Tn-glycopeptide antigens by CART cells enhances specificity.
• This multi-antigen recognition mechanism is proposed to prevent tumor escape due to antigen loss, thereby reducing the likelihood of relapse.