Phase II trial of 5 day continuous intravenous infusion of 6-thioguanine in patients with recurrent and metastatic squamous cell carcinoma of the head and neck.

Fifteen patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck received a 5 day continuous I.V. infusion of 6-thioguanine repeated every five weeks. Dose limiting toxicity was primarily hematological with grade III/IV leucopenia and thrombocytopenia seen in seven patients. Nausea and vomiting was moderate and well controlled with antiemetics. No complete or partial responses were observed, with a median time to progression of 58 days and a median survival of 227+ days for the entire group. Based on these results we do not recommend I.V. 6-thioguanine for the treatment of this disease.