In our multivariable regression model, adjusted for age and sex, there was no association between B2M levels and sCD25 levels (β = −0.048, p = 0.971), TIM-3 levels (β = −3.00, p = 0.196), PD-1 levels (β = 0.25, p = 0.123), or PD-L1 levels (β = −0.0065, p = 0.733) in patients with CLL (Supplementary Table S1). Here, PDCD1 is linked to B-cell chronic lymphocytic leukemia.