Phase II study of the farnesyl transferase inhibitor R115777 in patients with sensitive relapse small-cell lung cancer

Background: R115777 (tipifarnib, Zarnestra ™) is a farnesyl transferase inhibitor that blocks the farnesylation of proteins involved in signal transduction pathways critical for cell proliferation and survival. This multicenter phase II study was conducted to determine the efficacy, tolerability and pharmacokinetics of R115777 in patients with relapsed small-cell lung cancer (SCLC). Patients and methods: Patients who had a partial or complete response to their initial chemotherapy regimen, followed by at least 3 months off treatment before relapse (sensitive relapse) were eligible. R115777 was administered in 3-week cycles at a dose of 400mg orally twice daily for 14 consecutive days followed by 7 days off treatment. Results: Twenty-two patients were enrolled. The median progression-free survival was 1.4 months and median overall survival was 6.8 months. Non-hematological toxicities were predominantly grade 1-2 and included nausea (64%) and fatigue (60%). Grade 3-4 granulocytopenia and thrombocytopenia occurred in 27% and 23% of patients, respectively. Febrile neutropenia was not observed. Pharmacokinetic studies demonstrated peak plasma concentrations of R115777 2.6-4.5h after oral dosing and no significant drug accumulation. The trial was terminated because no objective responses were observed in 20 patients evaluable for response. Conclusions: R115777 showed no significant antitumor activity as a single agent in sensitive-relapse SCLC.