According to this finding, the targeting of PI3K/AKT pathway through idelalisib results in a dual effect in patients with CLL: an on-tumor effect leading to a reduced expression of HIF-1α and its target genes in leukemic cells, and an off-tumor effect leading to decreased concentrations of CXCL12 in patients’ sera. The gene discussed is CXCL12; the disease is neoplasm.