Phase II study of BKM120 in patients with advanced esophageal squamous cell carcinoma (EPOC1303)

BACKGROUND: PI3K/AKT/mTOR pathway is frequently overactive in esophageal squamous cell carcinoma (ESCC), making it an attractive treatment target. BKM120 is an oral pan-class I PI3K inhibitor with promising activity in several cancers. We prospectively investigated efficacy, safety, and biomarkers of BKM120 in advanced ESCC. We conducted a multicenter phase II study of BKM120 monotherapy in patients with pretreated advanced ESCC. METHODS: BKM120 (100 mg/day) was administered orally in a 28-day cycle. The primary end point was disease control rate (DCR). Tumor samples for all patients were collected for gene alteration analysis in a comprehensive genomic profiling assay. RESULTS: Of 42 patients enrolled, 20 had stable disease and two had confirmed partial response. One ineligible patient was excluded from the primary analysis, which met the primary end point (DCR 51.2%; 95% confidence interval [CI], 35.1–67.1). In the 42 patients, median progression-free survival and overall survival were 2.3 (95% CI 1.8–3.2) and 9.0 (95% CI 6.5–11.4) months, respectively. Common grade 3 or 4 adverse events were rash, anorexia, hyponatremia, and abnormal hepatic function; profiles of these events in this study were similar to those in previous studies of BKM120 monotherapy. No treatment-related deaths occurred. PI3K pathway activation was observed in patients with good clinical response. CONCLUSIONS: BKM120 monotherapy showed promising efficacy and a manageable toxicity profile even in patients with pretreated advanced ESCC. This study showed the potential target PI3K for ESCC, and further confirmatory trial will be necessary to confirm it. Unique ID issued by UMIN: UMIN 000011217.