Profile fluctuation of peripheral blood in advanced melanoma patients treated with nivolumab.

Melanoma is a malignant tumor of the melanocytes with an unfavorable clinical behavior. Nivolumab, a representative anti-programmed death 1 (PD-1) antibody, has recently been used for the treatment of metastatic malignant melanoma. However, there have been few appropriate biomarkers predicting the effect of nivolumab before the administration. Furthermore, the detailed characteristics of peripheral blood mononuclear cell (PBMC) profiles during nivolumab treatment remains unclear. In this study, we investigated fluctuations of PBMC profile during nivolumab treatment. PBMC analysis showed T-helper (Th)2-dominant conditions after a first course of nivolumab treatment. In a favorable case treated with nivolumab, a Th1/T-cytotoxic 1 shift was observed after nivolumab was administrated. These results suggest that flow cytometric analysis of PBMC may be helpful for the treatment of nivolumab.