Subcutaneously administered recombinant human interleukin-2 and interferon alfa-2a for advanced breast cancer: a phase II study of the Cancer and Leukemia Group B (CALGB 9041).

New and more effective treatments are needed for metastatic breast cancer. This study aimed to determine the effectiveness of a combination of subcutaneously administered recombinant human interleukin-2 (rIL-2), 1.5 MU/m(2) for 5 consecutive days repeated for 3 weeks, and interferon alpha-2a (IFN), 7.5 MU/m(2), administered subcutaneously three times per week. Women who had previously received 1-2 prior chemotherapy regimens for measurable inoperable, recurrent, or metastatic breast cancer were eligible. Of 40 patients accrued to the study, 32 were evaluable for response assessment. Toxicities were frequent but manageable. The most common grade 3 and 4 toxicities were lymphopenia (17%) and malaise/fatigue (24%). There were no complete responses, one partial response (3%), and six patients with stable disease (19%). Of the seven patients with partial response or stable disease, all had tumors that expressed hormone receptors. The median survival was 8.9 months and all patients have died. Good performance status was the most important predictor of survival. In this group of women with metastatic breast cancer, the overall prognosis was poor. This combination of rIL-2 and IFN was ineffective.