Second, our RNA-seq analysis of primary human MDS HSPC treated with anti-PD-1 antibody suggests the relevance of the S100A9-PD-1/PD-L1 circuit would also affect the use of erythropoietin as a hematopoietic stimulating agent in combination with anti-PD-1/PD-L1 treatment. The gene discussed is S100A9; the disease is myelodysplastic syndrome.