HLA-A and neoplasm: The underlying etiology for the role of HLA-A*02:01 on the worse prognosis might be attributed either to a selective sub-allele expression loss (e.g., selective gene loss, chromosome deletion/translocation, or mutation) and/or immune pressure for the selection of tumor cell clones not, or elusively, recognized through HLA-A*02:01 as a result of the heterogenic expression of tumor peptides specifically restricted by this allele.