Verapamil inhibits B-cell proliferation and tumor necrosis factor release and induces a clinical response in B-cell chronic lymphocytic leukemia.

Four B-CLL patients, treated with verapamil for cardiac problems, showed substantial reduction of lymphadenopathy in one, a 3- and 5-year stabilization of B-CLL in two patients, and a dramatic decrease in lymphocyte count, lymphadenopathy and splenomegaly in one stage IV patient. We therefore studied the effects of verapamil on B-CLL cells in vitro. In 13 samples we observed that verapamil strongly inhibited in vitro proliferation of pokeweed mitogen (PWM) stimulated and unstimulated cells. Using a cytotoxic bioassay, we found that verapamil markedly inhibited the spontaneous and PMW-induced release of tumor necrosis factor (TNF) by B-CLL cells. These findings suggest that verapamil may block B-CLL cell proliferation through inhibition of TNF release and thereby may contribute to the management of B-CLL.