Objectives: The pharmacodynamic effects of everolimus on gastrointestinal hormone levels have not been described in patients with pancreatic neuroendocrine tumors (pNETs). We report the effects of everolimus on gastrin and glucagon levels in patients with progressive pNET in RADIANT-1 (a single-arm phase II trial) and RADIANT-3 (a placebo-controlled, randomized, phase III trial).
Methods: Serum gastrin and glucagon levels were determined by immunoassay at baseline and at predose in subsequent treatment cycles in patients with elevated baseline hormone levels. The analyses included 158 patients from RADIANT-1 and 404 patients from RADIANT-3.
Results: In RADIANT-1, everolimus induced a rapid, sustained decrease in median gastrin and glucagon levels to approximately 60% and 70% of baseline levels, respectively. In RADIANT-3, everolimus consistently reduced median gastrin and glucagon levels by greater than 50% and approximately 40%, respectively (everolimus vs placebo, P < 0.0001), whereas with placebo, both hormones at each time point were essentially the same as their baseline levels. In patients with concomitant octreotide long-acting repeatable treatment, the moderate pharmacodynamic effect on lowering gastrin was greater than that seen with everolimus alone.
Conclusions: In addition to prolonging progression-free survival in patients with pNET, everolimus down-regulates excess production of 2 gastrointestinal hormones, which may help control their associated clinical syndromes.