https://www.selleckchem.com/ and everolimus. 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. 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. 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 ( <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 ( =0.001) and after complete remission following chemotherapy ( =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. PD-1 blockade might have therapeutic potential in refractory PCM patients after chemotherapy, especially in those with high- or intermediate-risk cytogenetic abnormalities. PD-1 blockade might have therapeutic potential in refractory PCM patients after chemotherapy, especially in those with high- or intermediate-risk cytogenetic abnormalities. Chromosomal analysis is essential for the diagnosis and risk stratification of all leukemia patients. Not surprisingly, racial differences in chromosomal aberrations (CA) in hematological malignancies could be found, and CA incidence in leukemia might change over time, possibly due to environmental and lifestyle changes. Thus, we compared the frequency and range of CA in patients with acute leukemia (AL) during two time periods (