Peripheral blood CD4+CD25+ T lymphocytes and TGF-β predict the prognosis in relapsed/refractory multiple myeloma treated with daratumumab.

For patients with relapsed/refractory multiple myeloma (R/RMM), it is indispensable to choose a combination regimen based on Daratumumab, a kind of CD38-targeting monoclonal antibody (mAb), which has prominent therapeutic advantages. However, a few patients still experienced rapid progression, and the predictors of prognosis are little known. Thus, we analyzed peripheral blood (PB) CD4+CD25+ T lymphocytes and transforming growth factor-β (TGF-β) of R/RMM patients before Daratumumab treatment, to clarify their correlation with survival. Flow cytometry (FCM) was employed to detect, analyze, and compare CD4+CD25+T lymphocytes. Enzyme-linked immunosorbent assay (ELISA) was utilized to quantify serum TGF-β. Clinical indicators were gathered and classified into quartiles. In R/RMM patients' PB, we compared these markers between the upper and lower three quartiles. We found that CD4+CD25+ T lymphocytes (pcs/µL) and TGF-β in the PB of the R/RMM patients were higher than those of the newly diagnosed MM (NDMM) patients. Additionally, serum TGF-β of R/RMM patients was positively correlated to serum creatinine (Scr) (P < 0.05). Finally, high CD4+CD25+ T lymphocytes (pcs/µL, 95% confidence interval [CI], 4.312-7.028, P = 0.001), CD4+CD25+ T lymphocytes (%, median PFS: 5.67 months, P = 0.043), and Scr (µmol/l, 95% CI, 5.378-7.422, P = 0.005) of R/RMM patients were significantly associated with inferior progression-free survival (PFS). These results suggest that patients with R/RMM are rich in CD4+CD25+ T lymphocytes and TGF-β. Additionally, R/RMM patients with elevated CD4+CD25+ T lymphocytes, TGF-β, and Scr before the treatment of daratumumab are more likely to have a poor prognosis.