Phase II study of everolimus (RAD001) in previously treated small cell lung cancer

Purpose: Mammalian target of rapamycin (mTOR) is a promising target in small cell lung cancer (SCLC). We designed a phase II study of everolimus, an mTOR inhibitor, in previously treated, relapsed SCLC. Experimental Design: Patients were treated with everolimus 10 mg orally daily until disease progression. The primary endpoint was disease control rate (DCR) at 6 weeks. PI3K/Akt signaling pathway biomarkers were evaluated on baseline tumor tissue. Results: A total of 40 patients were treated: 23 had 1 prior regimen/sensitive relapse, 4 had 1 prior regimen/refractory, and 13 had 2 prior regimens. Twenty-eight patients received 2 or more cycles of everolimus, 7 received 1 cycle, and 5 did not complete the first cycle. Best response in 35 evaluable patients: 1 (3%) partial response (in sensitive relapse), 8 (23%) stable disease, and 26 (74%) progression; DCR at 6 weeks was 26% (95% CI = 11-40). Median survival was 6.7 months and median time to progression was 1.3 months. Grade 3 toxicities included thrombocytopenia (n = 2), neutropenia (n = 2), infection (n = 2), pneumonitis (n = 1), fatigue (n = 1), elevated transaminases (n = 1), diarrhea (n = 2), and acute renal failure (n = 1). High phosphorylated AKT expression was modestly associated with overall survival (HR = 2.07; 95% CI = 0.97-4.43). Baseline S6 kinase protein expression was significantly higher in patients with disease control versus patients with progression (P = 0.0093). Conclusions: Everolimus was well tolerated but had limited single-agent antitumor activity in unselected previously treated patients with relapsed SCLC. Further evaluation in combination regimens for patients with sensitive relapse may be considered.