Everolimus in Neuroendocrine Tumors of the Gastrointestinal Tract and Unknown Primary

Purpose: The RADIANT-4 randomized phase 3 study demonstrated significant prolongation of median progression-free survival (PFS) with everolimus compared to placebo (11.0 [95% CI 9.2-13.3] vs. 3.9 [95% CI 3.6-7.4] months) in patients with advanced, progressive, nonfunctional gastrointestinal (GI) and lung neuroendocrine tumors (NET). This analysis specifically evaluated NET patients with GI and unknown primary origin.

Methods: Patients in the RADIANT-4 trial were randomized 2:1 to everolimus 10 mg/day or placebo. The effect of everolimus on PFS was evaluated in patients with NET of the GI tract or unknown primary site.

Results: Of the 302 patients enrolled, 175 had GI NET (everolimus, 118; placebo, 57) and 36 had unknown primary (everolimus, 23; placebo, 13). In the GI subset, the median PFS by central review was 13.1 months (95% CI 9.2-17.3) in the everolimus arm versus 5.4 months (95% CI 3.6-9.3) in the placebo arm; the hazard ratio (HR) was 0.56 (95% CI 0.37-0.84). In the unknown primary patients, the median PFS was 13.6 months (95% CI 4.1-not evaluable) for everolimus versus 7.5 months (95% CI 1.9-18.5) for placebo; the HR was 0.60 (95% CI 0.24-1.51). Everolimus efficacy was also demonstrated in both midgut and non-midgut populations; a 40-46% reduction in the risk of progression or death was reported for patients in the combined GI and unknown primary subgroup. Everolimus had a benefit regardless of prior somatostatin analog therapy.

Conclusions: Everolimus showed a clinically meaningful PFS benefit in patients with advanced progressive nonfunctional NET of GI and unknown primary, consistent with the overall RADIANT-4 results, providing an effective new standard treatment option in this patient population and filling an unmet treatment need for these patients.