Continuous-infusion topotecan and erlotinib: a study in topotecan-pretreated ovarian cancer assessing shed collagen epitopes as a marker of invasiveness.

Background. Continuous-infusion topotecan with erlotinib has the potential to reverse topotecan resistance due to drug efflux mechanisms. We assessed the activity of such a regimen in ovarian cancer patients previously failing bolus topotecan. Assay for shed collagen epitopes recognized by antibody HU177 during treatment explored its ability to reflect tumor invasion. Methods. Topotecan 0.4 mg/m(2) per day was administered by continuous infusion for 9-10 days every 3 weeks. Erlotinib, 150 mg orally, was administered on days 1-10 of each cycle. Cycles were repeated until progression or toxicity. Serum for shed HU177 collagen epitopes was collected weekly. This was a two-stage design to detect a CA-125 response rate of at least 20% in 30 patients after completing two treatment cycles. The trial would be terminated early if there were less than two CA-125 responses in 16 patients. Four or more CA-125 responses in 30 patients would justify further study of this regimen in prior topotecan treatment failures. Results. Six patients were enrolled, with four receiving three or more cycles and one achieving a partial response by cancer antigen 125 (CA-125) criteria. Shed epitope levels became undetectable on at least one measurement in all patients who received three or more cycles (Fig. 1A) and reappeared concomitantly with rises in CA-125 and clinical progression(Fig. 1B). After logistical delays, the trial was closed by the sponsor's decision to stop developing erlotinib in ovarian cancer. Conclusion. Continuous-infusion topotecan with erlotinib was found safe in six pretreated ovarian cancer patients; one met CA-125 criteria for partial response. Serial shed epitope levels to reflect invasiveness deserve further study.