Phase II study of everolimus with biomarker exploration in patients with advanced gastric cancer refractory to chemotherapy including fluoropyrimidine and platinum

Background: To evaluate the activity and safety of everolimus and identify potential biomarkers for efficacy of everolimus in patients with advanced gastric cancer (AGC), who failed both fluoropyrimidine and platinum. Methods: Fifty-four patients received everolimus (10 mg day ^-1). The primary objective was to determine the 4-month progression-free survival (PFS) rate, assumed to be 30%. We additionally investigated the potential biomarkers for everolimus as an exploratory endpoint in those who underwent tumour biopsies. Results :Two patients (3.7%) achieved partial response and the disease control rate (DCR) was 38.9%. At a median follow-up duration of 8.7 months, the 4-month PFS rate was 18.4%, not fulfilling the primary hypothesis, with a median PFS of 1.7 months and a median overall survival of 8.3 months. The high expression of pS6 ^Ser240/4 at baseline was significantly associated with higher DCR (P=0.043) and prolonged PFS (P=0.001). Grade 1/2 asthenia (96.3%) recorded as the leading toxicity and hyperglycaemia (20.4%) was the most common non-hematological grade 3/4 toxicity. Three patients experienced grade 3/4 pneumonitis. Notably, two experienced treatment-related deaths. Conclusion: Everolimus is active against a limited number of patients with AGC. pS6 ^Ser240/4 may be a potential predictive biomarker for everolimus, which requires validation. Careful monitoring is necessary despite generally favourable toxicity profile.