Verapamil reversal of clinical doxorubicin resistance in human cancer. A Wilshire Oncology Medical Group pilot phase I-II study.

A pilot study of the use of verapamil and adriamycin in patients with advanced malignancy was conducted to determine if the two drugs could be safely combined and to explore whether antitumor responses were frequent. The dosage of adriamycin was 50 mg/M2 every 3 weeks. Eight doses of verapamil were given orally every 6 hours, with adriamycin being administered after the fourth dose. In five patients 240 mg of verapamil taken every 6 hours produced unacceptable nausea, vomiting, hypotension, and arrhythmia. In eight patients, 120 mg of verapamil taken every 6 hours was tolerated moderately well. In four adriamycin-resistant patients, the combination of adriamycin and verapamil produced one partial response and two minor regressions. Further studies using this combination are warranted.