New Pipeline Identifies a Spliced Peptide That Could Target KRAS-Mutant Cancers in More Patients

The researchers developed an in silico-in vitro pipeline that first computationally predicted which spliced peptides carrying the KRAS G12V mutation would bind strongly to HLA-A*02:01. They then validated the candidates experimentally, confirming that the identified peptide is produced by proteasomes, transported by TAP proteins, and efficiently presented on HLA-A*02:01 complexes. The study used structural modeling and binding assays as part of the validation.

KRAS mutations are among the most common cancer-driving mutations, found in pancreatic, colorectal, and lung cancers. However, targeting them with immunotherapy has been challenging because the mutated peptides don't display well on common HLA types. This pipeline opens up a new strategy — using spliced peptides — that dramatically expands the pool of targetable epitopes and the number of patients who could benefit from KRAS-directed immunotherapy.

Proteasome-generated spliced peptides represent a vastly underexplored source of immune targets. While most cancer immunotherapy research focuses on conventional peptides, spliced peptides could exponentially increase the number of targetable epitopes. This study provides proof of concept that a systematic pipeline can identify clinically relevant spliced epitopes, with implications not just for KRAS-mutant cancers but for immunotherapy design more broadly.

This is a proof-of-principle study; the identified spliced epitope has not been tested for its ability to activate T cells in cancer patients. The pipeline's predictions need validation in clinical settings. The study focused on a single mutation (KRAS G12V) and a single HLA allele (HLA-A*02:01). The efficiency of spliced peptide generation by proteasomes in tumor cells in vivo remains to be confirmed. No clinical or animal model data were presented.