Purpose: To determine the maximal-tolerated dose (MTD) of infusional cyclosporine (CSA) with fixed-dose carboplatin (CBDCA).
Patients and methods: Clonogenic cytotoxicity assays were performed to assess the effect of CSA on reversal of resistance to CBDCA. The phase I study was performed in three phases. In phases 1 and 2, escalating-dose CSA (5, 7.5, 8.8, or 9.5 mg/kg/d) with fixed-dose CBDCA 300 or 250 mg/m2 were administered. Phase 3 required an initial cycle of CBDCA 250 mg/m2 alone, followed by combination therapy with CBDCA 250 mg/m2 and CSA (8.8, 9.5, or 10.0 mg/kg/d).
Results: Preincubation of platinum-resistant A2780 human ovarian cancer cells with CSA 2 micrograms/mL significantly enhanced CBDCA cytotoxicity in clonogenic assays. Fifty-one patients received 130 courses of therapy. The phase 1 MTD was thrombocytopenia (CSA 7.5 mg/kg/d and CBDCA 300 mg/m2) attributable to the effects of CBDCA alone. The phase 2 MTD was reversible nephrotoxicity (serum creatinine elevations to 3.6 and 4.4 mg/dL) and neutropenia (CSA 9.5 mg/kg/d and CBDCA 250 mg/m2). In phase 3, headache was observed in five patients and hypertension in one patient at CSA 10 mg/kg/d. The expected change in platelet count predicted for CBDCA alone was compared with the actual change; no excessive thrombocytopenia was observed with addition of CSA. Steady-state CSA levels of 2 micrograms/mL capable of reversing platinum resistance in vitro were observed. Four objective responses were observed.
Conclusion: CSA is effective in reversing CBDCA resistance in A2780 ovarian cancer cells. Short-term infusions of CSA < or = 8.8 mg/kg/d in combination with CBDCA are well-tolerated for heavily pretreated patients and result in CSA levels known to reverse CBDCA resistance in vitro.