A selective nonpeptide somatostatin receptor 5 agonist effectively decreases insulin secretion in hyperinsulinism

Congenital hyperinsulinism (HI), a beta cell disorder most commonly caused by inactivating mutations of beta cell K(ATP) channels, results in dysregulated insulin secretion and persistent hypoglycemia. Children with K(ATP)-HI are unresponsive to diazoxide, the only FDA-approved drug for HI, and utility of octreotide, the second-line therapy, is limited because of poor efficacy, desensitization, and somatostatin receptor type 2 (SST2)-mediated side effects. Selective targeting of SST5, an SST receptor associated with potent insulin secretion suppression, presents a new avenue for HI therapy. Here, we determined that CRN02481, a highly selective nonpeptide SST5 agonist, significantly decreased basal and amino acid–stimulated insulin secretion in both Sur1(−/−) (a model for K(ATP)-HI) and wild-type mouse islets. Oral administration of CRN02481 significantly increased fasting glucose and prevented fasting hypoglycemia compared to vehicle in Sur1(−/−) mice. During a glucose tolerance test, CRN02481 significantly increased glucose excursion in both WT and Sur1(−/−) mice compared to the control. CRN02481 also reduced glucose- and tolbutamide-stimulated insulin secretion from healthy, control human islets similar to the effects observed with SS14 and peptide somatostatin analogs. Moreover, CRN02481 significantly decreased glucose- and amino acid-stimulated insulin secretion in islets from two infants with K(ATP)-HI and one with Beckwith-Weideman Syndrome-HI. Taken together, these data demonstrate that a potent and selective SST5 agonist effectively prevents fasting hypoglycemia and suppresses insulin secretion not only in a K(ATP)-HI mouse model but also in healthy human islets and islets from HI patients.