Early clinical investigation of sulofenur with a daily schedule in advanced solid tumours

Sulofenur, a sulfonylurea, has demonstrated antitumour effect in preclinical studies. A phase I trial was initiated to study the clinical aspects. Sulofenur was given p.o. daily for a period of 28 days in 5-week courses. The initial dosage was 250 mg/m2 escalating to 700 mg/m2 daily with no dose modification for the individual patient at any given dose level; 38 patients with advanced solid malignant tumours were enrolled. Haemolytic anaemia was the main side effect. The toxicity was marked at dose levels of 600 and 700 mg/m2. Moderate methaemoglobinaemia also occurred. One case of reversible toxic hepatitis was observed. Generally was ALAT, and more moderately basic phosphatases, and LDH elevated. Tumour regression was not observed but one patient had stable disease throughout nine courses. The maximal detected plasma concentration of Sulofenur in this study was 348 x 10(-6) g/ml. In the present study the maximum tolerated dose (MTD) of Sulofenur was defined to 600 mg/m2. One conclusion from this study is that even at doses above that recommended for future studies-5-600 mg/m2-with this schedule, the suggested effective plasma level from preclinical studies could not be reached. The overall conclusion is that this schedule should not be recommended at all for future studies and the recommendation should be to try to find a schedule in which higher plasma levels can be achieved at a clinically tolerated dose.