To investigate the presence of CD8+ T cell populations reactive to HERV-derived peptides as a consequence of the malignant transformation and to further evaluate if HMA therapy impacts the T cell reactivity to our selected group of HERVs, we analyzed samples from 34 patients before and after AZA treatment (MDS, AML, and CMML; Supplementary Table 1). Here, CD8A is linked to chronic myelomonocytic leukemia.