Phase II Trial of Sunitinib Maintenance Therapy After Platinum-Based Chemotherapy in Patients with Extensive-Stage Small Cell Lung Cancer

Introduction: The prognosis for patients with extensive-stage small cell lung cancer remains poor. This trial was designed to evaluate the efficacy and toxicity of maintenance sunitinib after platinum-etoposide chemotherapy. Methods: Patients who demonstrated objective tumor response or stable disease after four cycles of platinum plus etoposide chemotherapy were eligible. Sunitinib was given at 50 mg daily for 4 weeks of a 6-week cycle until disease progression or unacceptable toxicity. The primary end point was 4-month progression-free survival (PFS) rate from initiation of sunitinib. Results: Sixteen patients were enrolled. Responses to platinum-etoposide were complete response (CR)/partial response (PR)/stable disease (SD) = 3/11/2. The median number of weeks on sunitinib was 4 (range: 1.4-20). Reasons for sunitinib discontinuation were disease progression (50%), toxicity (31%), and patient request (19%). Median PFS from the start of sunitinib was 2.5 months (95% confidence interval [CI], 0.8-3.1). Further accrual would have failed to reach the target PFS rate, so the study was terminated. There were no objective responses to sunitinib, but four patients (25%) had disease stability for 15, 15, 17, and 20 weeks. Median PFS and overall survival from the start of chemotherapy were 6.2 months (95% CI, 4.1-6.5) and 8.2 months (95% CI, 6.2-14.7), respectively. Grade 3 to grade 4 toxicity included thrombocytopenia (25%), fatigue (19%), muscle weakness (13%), and hypothyroidism (6%). Conclusions: Sunitinib did not seem to maintain disease stability after response to chemotherapy. Sunitinib was discontinued in half of patients due to toxicity or request to stop therapy. Although disease stability with sunitinib was noted in four patients, this approach does not seem to warrant further clinical study.