Mohamed, Amr

733 Background: Glucagon-like peptide-1 receptor agonists (GLP-1 RA) have advanced the treatment of type 2 diabetes mellitus (T2DM) yet their association with cancer risk remains subject of ongoing research. While case reports and pharmacovigilance data have linked GLP-1RA’s to pancreatitis, large randomized trials and observational studies have not consistently shown an increased risk of pancreatic cancer. Chronic pancreatitis (CP) is a well-established risk factor for pancreatic cancer, yet the impact of GLP-1 RA therapy in this high-risk population is unknown. In this study, we aim to evaluate the association between GLP-1 RA use and pancreatic cancer incidence among patients with CP, and among those with CP and T2DM. Methods: We performed a retrospective cohort study using ICD-10 codes within TriNetX, a healthcare database of over 150 million patients in the United States. In the first analysis, adult patients with pre-existing CP were identified, and the 5-year incidence of pancreatic cancer between GLP-1 RA (semaglutide, dulaglutide, tirzepatide, exenatide, liraglutide, and lixisenatide) users and non-users was compared from 2015-2025. In the subsequent analysis, we restricted the cohort to adults with CP and T2DM and repeated the comparison. Patients with prior diagnosis of pancreatic cancer were excluded from both analyses. All cohorts were propensity score matched (PSM) on age, sex, race, tobacco use, alcohol use, hypertension, hyperlipidemia, obesity, and pancreatic cysts. Results: We identified 95,391 with CP, including 3,139 GLP-1 RA users and 92,252 non-users. After PSM, GLP-1 RA use was associated with a lower incidence of pancreatic cancer (0.6% vs. 1.5%, OR 0.39 [0.22, 0.67]). Similarly, amongst patients with CP and T2DM, GLP-1 RA use was associated with a lower incidence of pancreatic cancer (0.7% vs. 1.6%, OR 0.44 [0.25, 0.75]). Conclusions: GLP-1 RA use was associated with a significantly reduced incidence of pancreatic cancer in all patients with CP and in those with CP and T2DM. Given the elevated cancer risk in CP, these findings suggest a potential protective effect of GLP-1RA use in this high risk population. Prospective studies will be important to further analyze and confirm this potential benefit.

632 Background: Paltusotine is an oral, nonpeptide, selective somatostatin receptor 2 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 effect of paltusotine on biomarkers of serotonin and 5-hydroxyindoleacetic acid (5-HIAA) was further explored. Methods: This exploratory study, without formal power calculations, included an 8-week randomized treatment phase (completed) and a 102-week open-label extension phase (currently ongoing). The purpose was to evaluate safety, pharmacokinetics, and exploratory efficacy endpoints, including changes in biomarkers of paltusotine treatment. Enrolled patients were adults with a stable, documented grade 1 or 2 neuroendocrine tumor (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 a 2-week period) or washed out of SRL therapy (symptoms previously controlled on SRL), with demonstrated symptom worsening after washout. Patients were randomized to once-daily paltusotine 40 mg or 80 mg; one optional uptitration (from 40 mg to 80 mg or 80 mg to 120 mg) was permitted. Blood samples for assessment of biomarkers (serum serotonin and plasma 5-HIAA) were collected longitudinally from screening to end of treatment. Upper limit of normal was prespecified as 541 ng/mL for serotonin and 22 ng/mL for 5-HIAA. This analysis focuses on changes in biomarker from baseline to the end of 8-week randomized treatment phase and after approximately one year (48 weeks). Results: Thirty-six patients (n=9 untreated; n=27 SRL washout) were randomized. Mean age was 60.8 years (range 35-83), and 52.8% were female. Nineteen patients had grade 1 NETs, and 17 had grade 2 NETs. As reported previously, treatment with once-daily, oral paltusotine was well tolerated and reduced the frequency and severity of CS symptoms, justifying further clinical development of the 80 mg dose. Mean serum serotonin decreased from 1553.0 ng/mL at baseline to 643.9 ng/mL at Week 8, and mean plasma 5-HIAA decreased from 245.1 ng/mL to 159.7 ng/mL. There was a trend of untreated patients achieving a greater reduction in comparison to washout patients. At 48-week follow-up, mean serum serotonin was stabilized at 791.50 ng/mL (n=20), and mean plasma 5-HIAA was stabilized at 190.45 ng/mL (n=20). Conclusions: Paltusotine significantly reduced serotonin and 5-HIAA levels, with effects maintained at 48 weeks. Biomarker reductions paralleled reductions in BM and flushing frequency. These findings support further investigation in the ongoing phase 3 study (CAREFNDR, NCT07087054). Clinical trial information: NCT05361668 .

605 Background: Multiple treatment modalities are available for localized hepatocellular carcinoma (HCC), and current Barcelona Clinic Liver Cancer (BCLC) guidelines recommend ablation for patients with a limited number of small tumors, not amenable to resection or transplantation. However, in recent years, stereotactic body radiation therapy (SBRT) has been increasingly used for localized disease. Patient outcomes based on treatment modality are not well understood. Methods: We conducted a retrospective analysis using the National Cancer Database (NCDB) to identify patients with a history of stage I/II HCC with tumors ≤ 5 cm who had received local therapy with either radiofrequency ablation (RFA) or SBRT between 2006 and 2021. A propensity score matched analysis was conducted accounting for patient demographics, facility region and tumor level characteristics, as well as an inverse probability of treatment weight-adjusted (IPTW) analysis. Overall survival was estimated using the Kaplan-Meier method. Results: We identified 14,516 patients meeting inclusion criteria, including 13,036 who received RFA and 1,480 who received SBRT. Demographic factors associated with receipt of SBRT included age >50 years, female sex, and treatment in the Middle Atlantic and East North Central regions, as well as clinical factors including larger tumor size (>3 to 5 cm), severe fibrosis/cirrhosis, and stage II disease ( p <0.05 for all). Factors associated with receipt of RFA include black race, higher Charlson-Deyo Comorbidity Scores, treatment at a comprehensive cancer program or integrated network cancer program, and treatment in the East South Central, West North Central, West South Central, Mountain, and Pacific Regions ( p <0.05 for all). Median time from diagnosis to treatment initiation was longer for those who received SBRT (66.3 vs 84.6 days, p <0.001). In a propensity matched analysis, mOS was 45.1 months for those receiving RFA vs 30.8 months for those receiving SBRT ( p <0.001). An IPTW analysis showed similar survival benefit with RFA over SBRT (mOS 51.0 vs 30.5 months, p <0.001). This OS benefit was observed in subset of patients with tumors <3cm in size. Conclusions: In this propensity matched analysis controlling for relevant patient and tumor factors, RFA was associated with improved survival. Prospective studies will be important to further analyze differences in patient outcomes.