IL17A and plasma cell myeloma: High frequencies of Th17 cells and IL-17A levels in tumor tissues, malignant ascites fluid, and PB have been previously observed in patients with solid tumors [22]–[27] as well as hematological malignancies such as acute myeloid leukemia [28], myelodysplastic syndrome [29], and multiple myeloma [30], where it correlated with markedly more favorable clinical outcomes.