High-Sensitivity HLA-I Immunopeptidome Profiling from Limited Clinical PBMC Samples

Human leukocyte antigen (HLA) molecules are central to immune surveillance, presenting antigenic peptides from self and non-self proteins to T cells, and directing adaptive immune responses. Assessment of HLA-presented peptides is increasingly critical in oncology, both for understanding tumor immunogenicity and for guiding immunotherapy strategies. Peripheral blood mononuclear cells (PBMCs) offer a minimally invasive and clinically accessible matrix for such analyses, enabling serial sampling and longitudinal monitoring in clinical trials.

Application of the immunopeptidomics profiling (IMPX) to PBMC samples has demonstrated clinical relevance, as exemplified by its use in the EMITT-1 trial where pharmacodynamic modulation of the immunopeptidome was observed in patients treated with an ERAP1 inhibitor (ESMO 2024, ASCO 2025). Despite these advances, isolating HLA-associated peptides from limited PBMC material remains technically challenging, underscoring the need for more sensitive and robust methods suitable for routine use in clinical settings.