Background@#
Plasma cell myeloma (PCM) is caused by immune dysregulation. We evaluated the expression of immune checkpoint
programmed cell death protein-1 (PD-1) on
T cell subsets in PCM
patients according to
disease course and
cytogenetic abnormalities.This study aimed to find a target group suitable for
therapeutic use of PD-1 blockade in PCM. @*
Methods@#A total of 188
bone marrow (BM) samples from 166 PCM
patients and 32 controls were prospectively collected between May 2016 and May 2017. PD-1 expression on BM
T cell subsets was measured using
flow cytometry. @*Results@#At
diagnosis, the median PD-1 expression on CD4+
T cells was 24.6%, which did not significantly differ from that in controls. After
stem cell transplantation, PD-1 expression on CD4+
T cells was higher than that at
diagnosis (P < 0.001), regardless of residual
disease. PD-1 expression on CD4+
T cells in
patients with residual
disease after
chemotherapy was significantly higher than that at
diagnosis (P = 0.001) and after complete remission following
chemotherapy (P = 0.044). PD-1 expression on CD8+
T cells was higher in PCM
patients with
cytogenetic abnormalities, including
monosomy 13, 1q gain, complex
karyotype, and hypodiploidy. @*Conclusions@#PD-1 blockade might have
therapeutic potential in refractory PCM
patients after
chemotherapy, especially in those with high- or intermediate-
risk cytogenetic abnormalities.