Everolimus plus octreotide LAR (E+O) versus placebo plus octreotide LAR (P+O) in patients with advanced neuroendocrine tumors (NET): Updated results of a randomized, double-blind, placebo-controlled, multicenter phase III trial (RADIANT-2).

Abstract

159 Background: Octreotide LAR has been the foundation of NET therapy; however, additional treatment options are needed. Everolimus, an oral inhibitor of mTOR, demonstrated promising antitumor activity in patients with NET as a single agent and in combination with octreotide LAR in two phase II studies. Methods: Patients (n = 429) with well or moderately differentiated advanced NET and history of carcinoid symptoms received oral everolimus 10 mg/d + octreotide LAR 30 mg IM q 28 days (n = 216) or placebo + octreotide LAR (n = 213). Common primary sites included the small intestine, lung, and colon. The primary endpoint was progression-free survival (PFS) per central review by RECIST. Crossover from P+O to open-label E+O was allowed at disease progression. Results: Median PFS (95% CI) with E+O was 16.4 months (13.67-21.19) vs. 11.3 months (8.44-14.59) for P+O. E+O was associated with a 23% reduction in risk of progression: HR = 0.77; 95% CI: 0.59-1.00; one-sided p-value = .026 (pre-specified significance boundary is p ≤ .0246). A high rate of informative censoring resulted in loss of power in central review results. Correcting for the informative censoring bias, the pre-specified marginal Cox model using inverse probability of censoring weights (IPCW) analysis showed a significant 5.5-month improvement in median PFS with E+O; HR = 0.60; 95% CI: 0.44-0.84, with one-sided p-value = .0014. The benefit of E+O was seen across all patient subgroups. Updated analyses of the impact of pre-study and post-progression octreotide LAR therapy will be reported. Most frequent drug-related adverse events (AEs) with E+O were stomatitis, rash, fatigue, and diarrhea; mostly grade 1-2. Grade 3-4 AEs reported in >5% were stomatitis, fatigue, diarrhea, infections, and hyperglycemia. Conclusions: In this large phase III trial, E+O provided a 5.1-month clinically meaningful increase in median PFS compared with P+O in the central adjudicated review. Correcting for the informative censoring bias, a significant PFS improvement of 5.5 months was seen, with a p value = .0014. The safety profile of E+O was acceptable. [Table: see text]