Probable HLA-mediated immunoediting of JAK2 V617F-driven oncogenesis.

Human leukocyte antigen class I (HLA-I) genotype has been found to influence cancer development through the presentation of mutational neoepitopes. However, our understanding of its effect on the development of myeloproliferative neoplasms (MPNs) remains limited. We aimed to elucidate the putative protective role of HLA-I alleles in the development of JAK2 V617F-driven MPNs using a population genetics approach. The variability of the HLA-I genotype had no effect on the presence of JAK2 V617F mutation. However, three alleles were found to be inversely correlated with the presence of JAK2 V617F mutation: HLA-A02:01 (p = 0.036), HLA-B35:01 (p = 0.017), and HLA-C15:02 (p = 0.033). The HLA-B35:01 allele was predicted to bind to a 9-mer peptide derived from JAK2 V617F mutant protein. Gene expression analysis revealed a lower expression of HLA-A and -B in MPN CD34+ cells compared with normal CD34+ cells, which was modulated by ruxolitinib and interferon-α treatment. In summary, we provide robust evidence that specific HLA-I molecules restrict JAK2 V617F-driven oncogenesis. JAK2 V617F+ stem cells evade immune surveillance through downregulation of the HLA-I expression. Therefore, the presence of specific HLA-I alleles might be a predictive marker for response to certain immunotherapies upregulating HLA-I expression. Finally, our findings have implications in the development of mutational neoepitope-based vaccines in MPNs.