Effects of bortezomib on Treg cells in multiple myeloma and its relationship with tumor burden and chemoresponse

AIM: To investigate the changes of regulatory T (Treg) cells in peripheral blood from multiple myeloma (MM) patients with bortezomib-based treatment, and to analyze the effects of bortezomib on Treg cells in MM and the relationship with tumor burden and chemoresponse. METHODS: Treg cells from 30 newly-diagnosed MM patients were detected by flow cytometry before and after bortezomib-based treatment. Meanwhile, 12 cases with conventional treatment were enrolled as controls. The correlation of Treg cell count with the levels of M protein and serum β₂-microglobulin (β₂-MG) was then statistically analyzed. RESULTS: The patients in early disease stage had lower Treg cell count. Decreased Treg cell count was found in 31 cases with chemoresponse (P<0.01), which did not exist in the 11 cases without chemoresponse. The patients achieved >50% serum β₂-MG reduction showed more obvious changes of Treg cell count than those achieved ≤50% serum β₂-MG reduction (P<0.05). The patients with bortezomib-based treatment showed more apparent decline in Treg cell count than the patients with conventional treatment, which were related to chemoresponse and serum β₂-MG reduction (P<0.05). CONCLUSION: Treg cell count is a reliable index of tumor budern. Both bortezomib-related treatment and conventional treatment can reduce Treg cell count, but the reduction is more obvious in bortezomib-related treatment. Such reduction is related to chemoresponse and tumor burden, suggesting the mechanism of bortezomib curing MM may be by the way of Treg suppression.