Phase I study of N-(phosphonacetyl)-L-aspartic acid (PALA)

N-(Phosphonacetyl)-L-aspartic acid, an inhibitor of aspartate transcarbamylase, was administered to 25 patients with advanced cancer by 10-minute infusion daily x 5 consecutive days to determine the toxicity and to look for evidence of therapeutic effect. Planned dose escalations ranged from 100 to 1250 mg/m2 (daily dose). Nausea, vomiting, and diarrhea were the most frequent toxic effects, with three of six patients treated at a daily dose of 1250 mg/m2 having severe diarrhea. Other toxic effects were encountered rarely and were not dose-limiting; these included mild leukopenia, thrombocytopenia, rash, stomatitis, and increases in SGOT. One patient with a widely metastatic carcinoid of unknown origin had an objective response lasting 6 weeks.