A phase II evaluation of ixabepilone in the treatment of recurrent/persistent carcinosarcoma of the uterus, an NRG Oncology/Gynecologic Oncology Group study

Background The primary objectives were to determine the objective response rate (ORR) and safety profile of ixabepilone in women with recurrent or persistent uterine carcinosarcoma (UCS). Secondary objectives included progression-free survival (PFS) and overall survival (OS). Exploratory translational objectives included characterization of class III beta tubulin expression and its association with response, PFS, and OS. Methods Patients had measurable disease; up to two prior chemotherapeutic regimens were allowed, but must have included a taxane. Women received ixabepilone 40 mg/m² as a 3 hour IV infusion on day 1 of a 21 day cycle. Treatment was continued until disease progression or unacceptable toxicity occurred. Results Forty-two women were enrolled, with 34 eligible and evaluable. Median age was 68 years. ECOG performance status was 0 in 56% of women, 38% had received radiation, and 15% had received 2 lines of chemotherapy. Overall ORR was 11.8% (4/34, 90% CI 4.2–25.1%); all were partial responses. Stable disease for at least 8 weeks was achieved in 8 patients (23.5%). Median PFS and OS were 1.7 mo and 7.7 mo, respectively, with a median follow-up of 37 mo. Six month PFS was 20.6%. Major grade ≥ 3 toxicities were neutropenia (47%), fatigue (15%), dehydration (15%), hypertension (15%), and hyponatremia (15%); grade 2 peripheral neuropathy was reported in 18%. In this small sample size, class III beta tubulin expression in the primary tumor was not associated with the response to ixabepilone, PFS, or OS. Conclusion In this cohort of women, single agent ixabepilone showed modest but insufficient clinical activity.