A phase I study of imatinib mesylate and paclitaxel in patients with advanced (stage IIIC/IV) or recurrent uterine papillary serous carcinoma (UPSC)

Abstract

16025 Background: Uterine serous carcinoma (USC) is a rare, aggressive uterine tumor biologically distinct from typical endometrial cancers. Imatinib mesylate (IM)-associated kinases (kit, abl, PDGFR-B) are overexpressed and activated in most tumors from patients (pts) with USC. Single agent paclitaxel (TAX) has a good response rate but short duration of response in pts with USC. The purpose of this study was to determine the maximum tolerated dose (MTD) and dose limiting toxicity (DLT) of escalated doses of IM with a fixed dose of TAX. Methods: Pts with newly diagnosed (stage IIIC/IV) or recurrent USC were eligible (pts were required to have tumors that expressed at least one of the IM-targeted kinases by immunohistochemistry). Measurable disease was not required. TAX was administered at 175 mg/m2 every three weeks. One dose reduction to 135 mg/m2 was allowed. IM was given daily (400 mg, 500 mg or 600 mg). A 3+3 design was implemented. Pts with measurable disease were treated until progression or treatment associated toxicity. Pts with no measurable disease were treated for six cycles. Results: 11 pts were enrolled. The median age was 62 years (47–79). A total of 50 cycles were administered. Three pts were treated at the first dose level (400 mg), 6 pts treated at the second dose level (500 mg), and 2 pts were treated at the highest dose level (600 mg). Three DLTs were observed (1 at 500 mg level and 2 at 600 mg level) including: rash, neutropenia, and fatigue. IM 500 mg daily and TAX 175 mg/m2 every three weeks was the MTD. There were 3 serious adverse events not related to treatment (infection, dyspnea, pain). Neutropenia was the most common grade 3 or 4 toxicity but only one patient required TAX dose reduction. 8 pts were evaluated for efficacy (2 with measurable disease, 6 with no measurable disease). 1 (of 2) pts with measurable disease had a partial response and was treated for 13 cycles. Of the 6 pts with no measurable disease, 2 recurred (5 and 10 months). The median disease free interval for the pts without recurrent disease was 22 months (6–30). Conclusion: Combination therapy of IM and TAX is well tolerated with minimal side effects in pts with advanced or recurrent USC. Initiation of the phase II component of this study is warranted to better evaluate efficacy. No significant financial relationships to disclose.