We also checked BM levels of the main MM pro-survival cytokine, IL-6, which is known to be higher in MM patients as compared with HDs (23); our data confirmed the increased BM IL-6 levels in patients with advanced stage of disease (SMM vs. MMD vs. MMR pg/ml: 2.830 vs. 8.270 vs. 7.625, Kruskal-Wallis test, p = 0.03) (Figure 4B); however, we did not find any correlation with PD-L1/PD-1 expression on PCs (Spearman r: 0.042, p = 0.77) and BM microenvironment cells (data not shown). This evidence concerns the gene PDCD1 and Miyoshi myopathy.