Randomized phase 3 trial of interferon gamma-1b plus standard carboplatin/paclitaxel versus carboplatin/paclitaxel alone for first-line treatment of advanced ovarian and primary peritoneal carcinomas: results from a prospectively designed analysis of progression-free survival. Interferon-gamma in the first-line therapy of ovarian cancer: a randomized phase III trial. Maintenance treatment with interferon for advanced ovarian cancer: results of the Northern and Yorkshire gynaecology group randomised phase III study. Randomized trial of adjuvant intraperitoneal alpha-interferon in stage III ovarian cancer patients who have no evidence of disease after primary surgery and chemotherapy: An intergroup study.
Interferon gamma (IFN-gamma) is a pleiotropic cytokine with antiproliferative, immunostimulatory, and chemosensitization properties. This trial was designed to evaluate IFN-gamma 1b plus carboplatin and paclitaxel in treatment-naive ovarian cancer (OC) and primary peritoneal carcinoma (PPC) patients.
                Eligible patients were randomized to 6 cycles of carboplatin/paclitaxel every 3 weeks or the same in combination with IFN-gamma 1b (100 microg 3x/wk subcutaneously). The primary endpoint was overall survival (OS) time (target hazard ratio (HR)=0.77). Secondary endpoints included progression-free survival (target HR=0.7), based on blinded review of serial imaging scans, physical exams, and CA-125 levels.
                847 patients were enrolled (OC 774, PPC 73) in Europe (n=539) and North/South America (n=308) from January 29, 2002 to March 31, 2004 and stratified according to: optimal debulking (n=271) versus suboptimal debulking with plans for interval debulking (PID) (n=238) or no PID (n=338). The study stopped early following a protocol-defined second interim analysis which revealed significantly shorter OS time in patients receiving IFN-gamma 1b plus chemotherapy compared to chemotherapy alone (1138 days vs. not estimable, HR=1.45, 95% CI=1.15-1.83). At the time of the analysis, 169 of 426 (39.7%) patients in the IFN-gamma 1b plus chemotherapy group had died compared to 128 of 421 (30.4%) in the chemotherapy alone group. Serious adverse events were more common in the IFN-gamma 1b plus chemotherapy group (48.5% vs. 35.4%), primarily due to a higher incidence of serious hematological toxicities (34.5% vs. 22.7%).
                Treatment with IFN-gamma 1b in combination with carboplatin/paclitaxel does not have a role in the first-line treatment of advanced ovarian cancer. Intraperitoneal treatment with interferon-gamma (IFN-gamma) has been shown to achieve surgically documented responses in the second-line therapy of ovarian cancer. To assess its efficacy in the first-line therapy, we conducted a randomized controlled trial with 148 patients who had undergone primary surgery for FIGO stage Ic-Illc ovarian cancer. In the control arm women received 100 mg/m(-2) cisplatin and 600 mg/m(-2) cyclophosphamide, the experimental arm included the above regimen with IFN-gamma 0.1 mg subcutaneously on days 1, 3, 5, 15, 17 and 19 of each 28-day cycle. Progression-free survival at 3 years was improved from 38% in controls to 51% in the treatment group corresponding to median times to progression of 17 and 48 months (P= 0.031, relative risk of progression 0.48, confidence interval 0.28-0.82). Three-year overall survival was 58% and 74% accordingly (n.s., median not yet reached). Complete clinical responses were observed in 68% with IFN-gamma versus 56% in controls (n.s.). Toxicity was comparable in both groups except for a mild flu-like syndrome, experienced by most patients after administration of IFN-gamma. Thus, with acceptable toxicity, the inclusion of IFN-gamm in the first-line chemotherapy of ovarian cancer yielded a benefit in prolonging progression-free survival. A randomised phase III trial was conducted to assess the role of interferon-alpha (INFalpha) 2a as maintenance therapy following surgery and/or chemotherapy in patients with epithelial ovarian carcinoma. Patients were randomised following initial surgery/chemotherapy to interferon-alpha 2a as 4.5 mega-units subcutaneously 3 days per week or to no further treatment. A total of 300 patients were randomised within the study between February 1990 and July 1997. No benefit for interferon maintenance was seen in terms of either overall or clinical event-free survival. We conclude that INF-alpha is not effective as a maintenance therapy in the management of women with ovarian cancer. The need for novel therapeutics or strategies to prevent the almost inevitable relapse of patients despite increasingly effective surgery and chemotherapy remains. Despite the improvement in progression-free and overall survival in patients with advanced ovarian cancer associated with platinum-taxane chemotherapy, strategies are needed to prevent the greater than 70% recurrence rate.
                The Southwest Oncology Group (SWOG) initiated a phase III intergroup trial of alpha-interferon (IFNalpha-26, Schering-Plough, Kenilworth, NJ) in weekly doses of 50 x 10(6) IU (for 6 doses) versus observation only in patients with no pathological evidence of residual disease at second-look surgery in 1988.
                Patient accrual was extremely slow and the trial was permanently closed in 1999 by the SWOG Data and Safety Monitoring Committee with 74 registered patients. Of these patients, 70 were evaluable for progression-free and overall survival. There was no significant difference between the two study arms in relation to median progression-free survival (P = 0.56). The median survival duration associated with intraperitoneal alpha-interferon had not been reached versus 87 months on the observation arm. In general, intraperitoneal alpha-interferon was well tolerated. There were no treatment-related deaths or grade 4 adverse events. Although no efficacy conclusions can be drawn from this prematurely closed trial, it should be noted that 57% of the patients on the observation arm recurred and all died, whereas 63% recurred and only 43% died on the intraperitoneal alpha-interferon arm.
                Although this was a negative study, there should continue to be interest in the use of biological therapy to improve survival of patients in complete remission following primary chemotherapy.
Implications for practice

Based on low quality evidence, the addition of interferon to first-line chemotherapy did not alter the overall survival in post-surgical women with advanced EOC compared with chemotherapy alone. There is low quality evidence to suggest that interferon in combination with chemotherapy worsened the progression free survival in post-surgical women with advanced EOC compared with chemotherapy alone. There is not enough evidence that interferon therapy alone alters overall survival or progression free survival compared to observation alone in post-surgical women who have undergone first-line chemotherapy.

Implications for research

Three of the five trials included in this review were stopped early and were, therefore, underpowered to detect any true effect of the intervention. The trials did not report the results of important outcomes in a uniform manner, preventing statistical aggregation of the results. Trial methodology was poorly reported resulting in unclear risk of bias. For clear recommendations to be made regarding the effectiveness of interferon in the treatment of advanced EOC, long-term, well conducted and adequately powered RCTs would be needed. However, the available data do not suggest that interferon has an adequately advantageous effect to warrant further investigation.