Introduction/Background Platinum-free interval predicts subsequent platinum sensitivity and is a prognostic factor in ovarian cancer. The aim of the study is to investigate response to non platinum-agents in platinum-resistant disease and the effect of prolonging the platinum-free interval.

Methodology The case records of patients treated with pegylated liposomal doxorubicin (PLD), weekly paclitaxel (WP) and weekly paclitaxel/2 weekly bevacizumab (WP/B) were reviewed. All patients had progressed within 6 months of prior platinum therapy. Response to chemotherapy was defined as Ca125 reduction from the baseline of more than 50%, clinical or radiological response.

Results A total of 103 patients were identified (69 had PLD, 26 had WP and 8 had WP/B). The median age was 62 years (range: 38 - 78). Only 11 patients had previous PARP-inhibitors. The response rates for PLD, WP and WP/B were 21.7%, 34.6% and 37.5%, respectively. Median overall survival times were 54 weeks for PLD, 58.7 weeks for WP and 62.5 weeks for WP/B. For the PLD treated patients, the Ca125 response increased progressively with each cycle; at cycle 2 = 6%; cycle 3 = 11%; cycle 4 = 17%; cycle 5 = 20% (trend significant between cycles 2 and 4, P = 0.03).

Nineteen patients were rechallenged with a platinum regime after progression with 36.8% (7/19) of the patients responding. The median duration of response in this group was 5 months (range: 2 - 16). Responses were only seen in patients with at least 6 months platinum-free interval.

Conclusion Rechallenge with platinum after PLD or weekly paclitaxel/bevacizumab resulted in a good response rate in selected patients. Prolongation of the platinum-free interval may lead to a partial reversal of acquired drug resistance. The sole use of early Ca125 to assess response in patients on PLD treatment before cycle 4 may result in discontinuation of the treatment in potential responders.

Disclosures None