Endocrine Abstracts

Background: Paltusotine is an oral, nonpeptide, selective SST2 receptor agonist. In a phase 2 study, treatment with once-daily paltusotine reduced the frequency and severity of carcinoid syndrome (CS) symptoms and was well tolerated. The anti-tumor effects of paltusotine were further explored.

Methods: This study included an 8-week randomized treatment phase and a 102-week open-label extension phase (OLE; currently ongoing). Enrolled patients were adults with a stable documented grade 1 or 2 NET and CS. These patients were actively symptomatic and either untreated with somatostatin receptor ligand (SRL) therapy (average of ≥4 bowel movements [BMs] per day or >2 flushing episodes per day in ≥2 days over 2-week period) or washed out of SRL therapy (symptoms previously controlled on SRL), with demonstrated symptom worsening after washout. Patients had stable disease in the 6 months prior to study entry. Patients were randomized to once-daily paltusotine 40 mg or 80 mg; one optional uptitration of 40 mg (to 80 mg or 120 mg) was permitted. Patients who completed the randomized treatment phase were eligible to enter the OLE. Radiographic tumor assessments (CT or MRI) were conducted pretrial, at week 10, week 36, week 70, week 110, and at end of treatment. At each assessment, investigators reported (yes/no) whether imaging represented disease progression, and “investigator-assessed progression-free survival (PFS)” was based on the overall impression of imaging results. This preliminary analysis (data cutoff: May 21, 2025) assessed tumor progression per investigator’s assessment; the Kaplan-Meier method was used to calculate the PFS.

Results: Thirty-six patients (n = 9 untreated; n = 27 SRL washout) were randomized (paltusotine 40 mg/day, n = 18; paltusotine 80 mg/day, n = 18). This analysis included 32 patients with baseline CT/MRI scans who continued into the OLE. Median age was 60 years (range 35-83); 53.1% were female; 8 untreated and 24 SRL washout; and 16 with grade 1 NETs and 16 with grade 2 NETs. At the data cutoff, the median follow-up was 14 months and median PFS had not been reached. The overall PFS rate at 12 months was 74%. The PFS rate was similar in untreated (75%) and washout (72%) patients. PFS rate by tumor grade was 82% for grade 1 and 65% for grade 2.

Conclusions: The observed PFS rate (74%) after 1 year of treatment with paltusotine, in this preliminary analysis of a phase 2 study, is encouraging data and warrants further investigation in the ongoing CAREFNDR Phase 3 study.

Abstract ID #33401