Safety and efficacy of NAD depleting cancer drugs: results of a phase I clinical trial of CHS 828 and overview of published data
Depletion of cellular nicotinamide adenine dinucleotide (NAD) by inhibition of its synthesis is a new pharmacological principle for cancer treatment currently in early phases of clinical development. We present new and previously published data on the safety and efficacy of these drugs based on early clinical trials. A phase I clinical trial of CHS 828 in patients with advanced solid tumours was performed. Published clinical trials on NAD depleting drugs for cancer treatment were summarised for safety and efficacy. Seven patients with previously treated solid tumours received oral administration of CHS 828 in the dose range 20–80 mg once weekly for 3 weeks in 4 weeks cycles. Toxicity was dominated by gastrointestinal symptoms including nausea, vomiting, diarrhoea, constipation, subileus and gastric ulcer. One patient had thrombocytopenia grade 2. There were two cases each of grade 3–4 hyperuricemia and hypokalemia. Safety and efficacy of the NAD depleting drugs CHS 828 and FK866 have been reported from four phase I clinical trials, including a total of 97 patients with previously treated solid tumours. Outstanding toxicity reported was thrombocytopenia and various gastrointestinal symptoms. No objective tumour remission has been observed in the total of 104 patients treated in the above early trials. Critical toxicity from NAD depleting cancer drugs to consider in future trials seems to be thrombocytopenia and various gastrointestinal symptoms. Efficacy of NAD depleting drugs when used alone is expected to be low.