Interestingly, this dual action on HIF-1α, which reflects on-tumor and off-tumor effects, was also confirmed on a small cohort of idelalisib-treated patients, who showed, in parallel to a decreased expression of the pro-survival factor HIF-1α in the leukemic cell compartment, a reduction in CXCL12 serum concentrations and a modification of the monocytic and endothelial architecture in the BM microenvironment. The gene discussed is CXCL12; the disease is neoplasm.