Purpose: Pyrazoloacridine (PZA) is an investigational nucleic acid binding agent that inhibits the activity of topoisomerases 1 and 2. We conducted a phase II clinical study to determine the efficacy and toxicities of PZA in patients with metastatic breast cancer (MBC).
Experimental design: In this phase II multicenter study, patients who were treated with no more than one prior chemotherapy for MBC were treated with 750 mg/m² of PZA given as a 3-hour intravenous infusion every 3 weeks. Treatment cycles were continued until disease progression or unacceptable toxicities. The study was designed to distinguish between a response rate of < 15% vs > 30% (alpha = 0.10, beta = 0.10) using Simons optimal 2-stage design. At least 2 responses were required in the first 12 patients in the 1st stage and 6 of 35 in the 2nd stage to recommend the agent for further study.
Results: Two patients in the first stage had a response allowing accrual to second stage. A total of 15 patients (out of 35 planned) were treated on the study prior to premature closure. Three patients had a partial response (20%) lasting 4.5-6 months. Two patients had stable disease for 3 and 5 months. The dose limiting toxicity was granulocytopenia with ten patients requiring dose reduction or dose delay for grade 4 neutropenia. Other grade 3 and 4 toxicities include vomiting (n = 2), nausea (n = 2), neurotoxicity (n = 1), fatigue (n = 1), anemia (n = 1), dyspnea 9n = 1) and renal (n = 1).
Conclusions: Pyrazoloacridine demonstrated modest activity in patients with metastatic breast cancer.