Several immune factors should be considered as predictors of CML relapse after treatment interruption such as low levels of CD56+ cells with low expression of CD16 and CD94/NKG2 receptors, impaired synthesis of proinflammatory cytokines or cytotoxic proteases from NK and NKT cells, low levels of CD8± TCRγβ+ T cells, as well as KIR haplotype BX and homozygosis for HLA-E*0103, which is a potential predictive biomarker never explored before. The gene discussed is HLA-E; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.