Clinical studies with rubidazone.

One hundred and thirty-three patients, 94 with acute luekemia and 39 with solid tumors, received rubidazone, alone or in combination, at M. D. Anderson Hospital. The initial study, a phase I--II study carried out in 39 patients with acute leukemia, revealed substantial antileukemic activity with optimal results at a dose level of 450 mg/m2. Toxic manifestations included an acute reaction suggestive of histamine release with dose-limiting mucositis at a dose of 600 mg/m2. Forty-seven patients with acute leukemia were treated at phase II dose levels. Thirteen of 32 patients (42%) with acute myelogenous leukemia and seven of ten patients (70%) with acute lymphocytic leukemia achieved complete remission. Twenty-seven previously untreated patients with acute leukemia who were greater than 50 years old were treated with rubidazone in combination with cytosine arabinoside, vincristine, and prednisone. Fifteen patients (50%) achieved complete remission including 12 of 15 patients (73%) who were treated at a dose of 200 mg/m2 of rubidazone on Day 1 and a dose of 70 mg/m2/day X 7 days of cytosine arabinoside (continuous infusion). For patients with solid tumors, the dose-limiting toxic effect was myelosuppression at a dose of 200 mg/m2. Other toxicity at that dose level was minimal. The best responses were seen in patients with carcinoma of the period with two of four evaluable patients showing objective tumor regression. Of six previously untreated patients with thyroid carcinoma none responded, and in a phase II study of patients with breast cancer there were no partial remissions among 13 patients. Cardiac toxicity, manifested by congestive heart failure, occurred in seven patients at cumulative doses of 1050--2600 mg/m2 of rubidazone; all patients had had prior anthracycline therapy at low doses. Rubidazone has been shown to be an active antileukemic agent, but appears to be less active than Adriamycin in our studies of patients with solid tumors.