The purpose of this study was to estimate the response rate of 26-h continuous infusion cyclosporine A (CSA) combined with carboplatin (CBDCA) and subcutaneous alpha-interferon (IFN), in recurrent ovarian cancer (OC), and to measure their effects on CBDCA pharmacokinetics. OC patients relapsing following platinum-based chemotherapy received CBDCA area under the curve (AUC 3) with CSA and IFN, every 3 weeks. The pharmacokinetics of CSA and CBDCA were determined in a subset of patients. Thirty patients received 84 courses of therapy. Three partial responses were observed. Nine patients were stable for >4 months. Toxicity was similar to that observed in our previously reported phase I study and consisted of myelosuppression, nausea, vomiting, and headache. The mean end of infusion CSA level (high-performance liquid chromatographic assay [HPLC]) was 1109 +/- 291 microg/mL (mean +/- SD). CBDCA pharmacokinetics revealed a measured AUC of 3.61 versus a targeted AUC of 3, suggesting a possible effect of IFN on CBDCA levels versus errors in the estimation of CBDCA clearance using measured creatinine clearance. Steady-state levels of >1 microg/mL CSA (HPLC assay) are achievable in vivo. Insufficient clinical resistance reversal was observed in this study to warrant further investigation of this combination.