PAP-1 (1) at a concentration of 20 μM, and clofazimine (3) at a concentration of 1 or 10 μM in combination with the multi-drug resistance (MDR) pump inhibitors (MDRi) cyclosporine H (4 μM) and probenecid (100 μM), which induced mild apoptosis in cancer cells (human SAOS2, mouse B16F10 melanoma, and human B-CLL) by specifically inhibiting KV1.3. The gene discussed is KCNA3; the disease is B-cell chronic lymphocytic leukemia.