Phase II study of 5-azacytidine in solid tumors

One hundred and seventy-seven patients were evaluated after therapy with 5-azacytidine using a dose of 1.6 mg/kg/day X 10 days followed by a maintenance regimen. One hundred and forty-eight of the patients received the drug by rapid iv infusion and 29 received the drug daily by and infusion that lasted between 18 and 24 hours. Hematologic toxicity was significant but transient in both groups. Nausea was severe using the rapid iv infusion and minimal with the slow infusion. Antitumor effect was seen in 17% of the evaluable patients with carcinoma of the breast and 21% of the patients with malignant lymphomas. Occasional responses were seen with a variety of other solid tumors. The responses were transient, and clinically, resistance to 5-azacytidine appeared to develop quite rapidly. No clear-cut difference was seen in response rates or duration of response between the two groups of patients. Cross resistance to other anticancer agents was not noted. It is believed that the drug is only of minimal value as a single agent in solid tumors using either of the methods of administration described.