Results of a Phase II Trial Testing the Resensitization With Trabectedin in Platinum-resistant Ovarian Cancer

Background/aim: In patients with advanced platinum-resistant ovarian cancer we prospectively evaluated whether trabectedin could resensitize the tumor cells to platinum rechallenge.

Patients and methods: Upon progression to platinum-based chemotherapy, trabectedin was administered as a 3-hour infusion every three weeks and subsequently crossed over to carboplatin/carboplatin-based combinations. The primary endpoints comprised objective response rate (ORR) and time to progression after trabectedin (TTP Trab). Secondary endpoints included ORR following platinum post-trabectedin, the growth modulation index (GMI) assessed as the ratio of successive TTP to platinum, given after (TTP2) and before (TTP1) trabectedin, quality of life (QoL), and ancillary translational studies.

Results: Ten patients with platinum-resistant ovarian cancer from a single institution were treated with trabectedin, one of whom achieved a partial response (PR) reaching the ORR of 10% and six had stable disease (SD) for a disease control rate (DCR) of 70%. After the treatment with platinum post-trabectedin, one patient achieved a PR and two had SD, attaining a rate of resensitization to platinum of 37.5%. The median TTP with trabectedin treatment was 15.0 weeks, while eight patients who received platinum post-trabectedin had the median TTP2 of 19.9 weeks. One patient reached the threshold of GMI >1 (12.5%) as indicator of clinical benefit. QoL of patients was not deteriorated with trabectedin. Predictive biomarkers of response to trabectedin and/or re-exposure to platinum could not be identified.

Conclusion: Although trabectedin did not achieve a wide resensitization to platinum in this heavily pretreated platinum-resistant population, a significant number of patients attained disease control.