Phase I trial of retinol in cancer patients.

Vitamin A (all-trans-retinol) and its analogues are undergoing evaluation as antineoplastic and chemoprevention agents. Because its toxicity and activity are poorly defined, we have completed a phase I trial of retinol. Retinol was administered to 13 cancer patients in daily doses ranging from 100,000 units/m2 to 350,000 units/m2. Neuropsychiatric changes were the earliest dose-limiting symptomatic toxicities, noted in 3 of 5 patients receiving more than 240,000 U/m2 for 3-4 months. Two patients receiving more than 270,000 U/m2 developed hepatomegaly after 3 and 4 months. Liver biopsies were consistent with vitamin A toxicity. Three patients receiving 200,000 U/m2 developed an increase in serum triglycerides concentration. Mild skin and mucous membrane dryness occurred in most patients receiving more than 150,000 U/m2. A mixed response was seen in one patient with melanoma. Because of neuropsychiatric and hepatic toxicity a retinol dose of 200,000 U/m2/day is recommended for future phase II trials.