A phase II trial of capecitabine (C) in combination with the farnesyltransferase (FT) inhibitor (FTI), tipifarnib (T), in patients (pt) with metastatic breast cancer (MBC): ECOG trial 1103

Abstract

1036 Background: Approximately 30% of human cancers have mutated Ras genes that produce proteins that remain in an active state causing uncontrolled proliferative signals. Post-translational modification of Ras include farneyslation catalyzed by FT. Tipifarnib (R115777) is an oral FTI active against human tumor cell lines and exhibiting modest single agent activity in pts with previously treated MBC. A previous phase I trial reported that CT inhibited farneyslation in peripheral blood mononuclear cells without affecting the pharmacokinetics of either agent. Objective: To evaluate objective response rate (ORR) of CT in taxane refractory MBC and to secondarily evaluate associated toxicity and progression-free survival (PFS). Methods: Pt with measurable MBC, previously treated (rx) with an anthracycline and relapse on a taxane or within 30 days (d). Study rx: T- 300 mg, po BID × 14 d plus C- 1,000 mg/m2, po BID × 14 d, followed by 7 d rest. Tumor reassessment was repeated q 3 cycles. The study was designed to detect improvement in ORR from 25% with C alone to 40% for the CT combination (90.5% power; type I error rate of 9.9%; 21 responses in 64 eligible pt needed to be promising. Results: 66/71 pt are available for primary analysis. Median age 50 yrs. Performance status: 0–1, 100%. ORR: PR-4.8% (3/62) [95% CI 0.01, 0.13], SD - 21% (13/62) [ 95% CI 0.12, 0.33]. Median survival - 10.6 months. Toxicity (%): anemia - 8(G3/4), neutropenia - 30 (G3/4), thrombocytopenia - 8 (G3/4), HFS-8 (G3), nausea/vomiting - 11(G3), diarrhea - 8 (G3), sensory neuropathy - 5 (G3). Conclusion: CT in taxane -refractory MBC has low antitumor activity without excessive toxicity. More mature data, including PFS, will be presented. No significant financial relationships to disclose.