Intraperitoneal interferon-alpha in residual ovarian carcinoma: a phase II gynecologic oncology group study

The purpose of this study was to confirm the activity of interferon-alpha intraperitoneally in minimal residual epithelial ovarian cancer in a Phase II multi-institutional trial and to investigate the activity of the agent based on prior response to first-line platinum compounds.

Ninety-two patients with minimal residual (<0.5 cm) epithelial ovarian cancer at reassessment laparotomy were entered into a multicenter trial of intraperitoneal interferon-alpha given for 12 cycles unless disease progression or unacceptable toxicity occurred first. Patients were considered favorable if they were platinum sensitive and/or relapsed 6 months or longer after completing treatment and unfavorable if they were platinum insensitive and/or relapsed shorter than 6 months after completing treatment and/or had stable or progressive disease during initial therapy. A third-look laparotomy was performed within 12 weeks of completion of treatment in those patients who were in clinical remission.

Eighty patients were clinically evaluable for toxicity only (48 favorable, 32 unfavorable) and 46 of them were evaluable for response, of whom 25 were favorable (platinum sensitive) and 21 unfavorable (platinum resistant). In the favorable group, there was a 28% surgically documented response rate (7/25 patients): 16% (4/25) had complete responses (negative reassessment operation), 12% (3/25) had partial responses, 32% (8/25) were nonresponders, and 40% (10 patients) developed progressive disease before planned reassessment operation. In the unfavorable group, there were no responding patients: 6 were nonresponders at reassessment operation and 15 developed progressive disease before planned reassessment operation. Of the 80 patients evaluable for toxicity, the most common adverse effects that were more than grade 2 were gastrointestinal (12; 15%), fever (8; 10%), neutropenia (7;9%), and leukopenia (6; 8%). Grade 4 toxicity was seen in 5 patients; each had fever and gastrointestinal toxicity, and 1 each had neutropenia and thrombocytopenia.

Interferon-alpha is an active and generally well-tolerated agent in favorable patients with minimal residual epithelial ovarian cancer at second-look surgery. These results are comparable to those achieved with cytotoxic chemotherapy. If Phase III trials are considered in the patients with minimal residual ovarian cancer, they should be limited to the platinum-sensitive patient population.