Toxicity and clinical tolerance of lonidamine.

The new anticancer agent lonidamine has been recently revisited for the treatment of various solid tumors, due to its peculiar and unusual mechanism of action (ie, interference with energy metabolism of tumor cells, morphologically displayed by the appearance of "condensed mitochondria"). First generation trials have in fact demonstrated therapeutic activity and an unusual toxicity profile. Lonidamine is devoid of conventional side effects induced by antiproliferative agents (ie, myelosuppression, stomatitis, cystitis, alopecia, renal, hepatic, and cardiac toxicity). No serious or life-threatening adverse reactions have been recorded even over long term treatment periods. Given as a single agent (in daily doses ranging between 300 and 900 mg) lonidamine induces the following side effects: myalgia, testicular pain, asthenia, ototoxicity, nausea and vomiting, gastric pain, and drowsiness. Hyperesthesia and photophobia have also been reported. In combination with radiotherapy (in oral daily doses ranging between 300 and 450 mg) lonidamine was well tolerated, without any reported evidence of additional toxicity. When associated with cytotoxic agents no enhanced toxicity was observed. In particular, myelosuppression and other conventional nonhematological adverse reactions were never greater than would be expected with chemotherapy alone. The same applies to toxicity and tolerance of lonidamine when used concurrently with hypertermia. The data collected from large series of cancer patients treated with this new agent show that lonidamine is a safe drug whether used alone or in combination with other effective anticancer treatments. The reported therapeutic efficacy and the peculiar toxic profile make lonidamine an interesting new drug for future clinical trials.