PDCD1 and myelodysplastic syndrome: Using regression analysis, we identified a negative (inverse) correlation between Casp1 and PD-L1 (rho = −0.41, p = 0.07) and a positive correlation between PD-L1 and PD1 (rho = 0.42, p = 0.07) in MDS patients (Figure 2A; Table S2).