One of the main human MHC class I genes; HLA-A alleles such as HLA-A*02:01 determine which tumor peptides can be displayed to CD8+ T cells.
HLA-A is a highly variable class I HLA gene. Its protein products sit on the surface of most cells and display short intracellular peptides, giving CD8+ T cells a way to inspect what the cell is making.
In neoantigen vaccine work, HLA-A matters because each allele has its own peptide-binding preferences. HLA-A*02:01 is especially common in published datasets and TCR programs, so many prediction models and engineered TCR examples are richest for A*02:01-presented targets.
That data abundance is useful but also a bias. A vaccine or TCR workflow has to run against the patient's actual HLA type, not just the easiest allele to model; otherwise promising mutations may be invisible in one patient and actionable in another.
HLA-A*02:01 is a common allele of the HLA-A class I gene. It is heavily represented in immunology datasets and cancer-immunotherapy studies, which is why many neoantigen and TCR examples use A*02:01-presented peptides.
A neoantigen can only be targeted if one of the patient's HLA molecules presents it. HLA-A alleles define part of that presentation space, so the same tumor mutation may be targetable in an HLA-A*02:01 patient and not in someone with a different allele.