Phase II trial of the dopaminergic inhibitor pimozide in previously treated melanoma patients.

Pimozide, a potent neuroleptic which inhibits the release of pituitary releasing factors and is an effective dopamine antagonist, was administered to 30 patients with previously treated metastatic melanoma. Six patients were inevaluable because of poor drug tolerance (two), disease progression within 1 week and death within 2 weeks (three), and death from other causes (one). Among the 24 evaluable patients, two had complete response, two had partial response, and two had disease stabilization. Responses were observed in soft tissue, lymph nodes, liver, and lung. Toxic effects consisted of extrapyramidal manifestations in nine patients and malaise in seven. Pimozide has activity in patients with previously treated metastatic melanoma (17% response rate in evaluable patients) and merits consideration of further study in combination regimens.