Structural basis for oligoclonal T cell recognition of a shared NRAS cancer neoantigen

Area of Science:

• Immunology
• Structural Biology
• Computational Biology

Background:

• T cell receptors (TCRs) are crucial for recognizing cancer neoantigens, driving anti-tumor immunity and the efficacy of immunotherapies.
• Understanding the structural basis of TCR recognition of neoantigens is vital for developing effective cancer treatments.

Purpose of the Study:

• To elucidate the structural mechanisms by which TCRs recognize a specific neoantigen derived from the NRAS^Q61K mutation.
• To investigate the structural basis for distinguishing between mutant and wild-type NRAS peptides presented by HLA-A1.
• To evaluate the accuracy of AlphaFold-based modeling for TCR-peptide-MHC complexes.

Main Methods:

• X-ray crystallography was used to determine the structures of TCRs in both unbound and bound states with the NRAS^Q61K-HLA-A1 complex.
• Comparative structural analysis was performed to identify distinct binding modes and chemical strategies employed by different TCRs.
• AlphaFold-based modeling was benchmarked against experimental structures to assess predictive accuracy.

Main Results:

• Structural insights reveal distinct TCR engagement strategies for recognizing the NRAS^Q61K neoantigen versus wild-type NRAS.
• The study explains how the NRAS^Q61K mutation creates a neoantigen recognizable by T cells.
• AlphaFold model accuracy for TCR-peptide-MHC interactions was found to be variable, influenced by conformational plasticity.

Conclusions:

• The findings provide a detailed structural understanding of cancer neoantigen recognition by TCRs.
• This work offers critical insights into the molecular basis of anti-tumor immunity and immunotherapy.
• The study highlights the need for improved computational methods for modeling TCR-peptide-MHC interactions in cancer research.