Phase I Study of Lenalidomide in Solid Tumors

Background The primary objectives of this phase I study were to define a tolerable dose and to describe the toxicity of lenalidomide administered as a daily oral dose for 4 weeks followed by a 2-week rest period (6-week cycle) in patients with solid tumors that were refractory to standard treatment. The secondary objective was to document any antitumor activity. Methods Key eligibility criteria included a performance status of 0–2 and acceptable hematologic, hepatic, and renal function. The dose was escalated from 5 to 10 to 25 mg/day. Nine cycles (54 weeks) were planned unless the patient developed intolerable toxicity or experienced tumor progression. Dose-limiting toxicity was defined as nonhematologic toxicity of grade 3 or higher and hematologic toxicity of grade 4 or higher occurring in cycle 1. Results Overall, 20 patients were enrolled. One patient was ineligible due to a thromboembolic event within the preceding 6 months, but this was not known at enrollment and this patient was included in the analysis. Three, five, and 12 patients were treated with 5, 10, and 25 mg/day, respectively. One patient on 25 mg/day developed grade 3 motor neuropathy in cycle 1, and this was the only dose-limiting toxicity. Moderate dose-dependent and reversible hematologic toxicity was observed. The nonhematologic toxicities were otherwise mild to moderate over multiple cycles of lenalidomide. One patient had a partial response, and three patients had stable disease; three of these patients had non-small cell lung cancer. Conclusion The recommended dose of lenalidomide for further studies in patients with solid tumors is 25 mg/day for 4 weeks followed by a 2-week rest period.