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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.

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.

Objective: In this study, we evaluate the utility of ctDNA analysis in a large cohort of patients for whom ctDNA testing was ordered commercially with real-world application. Summary Background Data: Circulating tumor DNA (ctDNA) has emerged as a prognostic and predictive biomarker for assessing post-surgical molecular residual disease (MRD) and response to treatment. Methods: A real-world data analysis was performed using commercial ctDNA testing (SignateraTM) from patients (N=795, n=5,971 plasma samples) with stage I-III colon cancer treated at multiple US institutions. The association of ctDNA detection within the MRD window, during surveillance, and the impact of ACT was correlated with patient outcomes. Results: ctDNA-positive patients during the MRD window and surveillance showed significantly shorter DFS compared to ctDNA-negative patients (hazard ratio (HR): 9.85, P<0.0001; HR: 26.91, P<0.0001). Multivariate analysis of the MRD window revealed ctDNA-positivity as the most significant factor associated with inferior DFS (adjHR: 7.7, P<0.001). MRD-positive patients who received ACT showed improved DFS compared to patients observed post-surgery (adjHR: 6.1, FDR adj P=0.0007). No ACT benefit was observed in MRD-negative patients (adj HR: 1.20, FDR adj P=0.768). On evaluating ctDNA dynamics from MRD to surveillance, patients who remained ctDNA-positive or converted from negative to positive showed a significantly inferior DFS (HR: 34.40, P<0.0001; HR: 13.65, P<0.0001) compared to persistently ctDNA-negative patients. Conclusions: Postsurgical ctDNA detection is prognostic of relapse and potentially predictive of ACT benefit in patients with resectable colon cancer, which may enable personalized surveillance, intervention, and/or trial options, ultimately improving patient outcomes.

4123 Background: Atezolizumab plus bevacizumab is the most commonly utilized first-line therapy for advanced HCC. However, the optimal choice for second-line treatment remains uncertain, particularly between different tyrosine kinase inhibitors including lenvatinib and cabozantinib. This study aims to compare survival outcomes of patients with metastatic HCC who received either lenvatinib or cabozantinib as second-line therapy following frontline treatment with atezolizumab plus bevacizumab. Methods: This retrospective cohort study utilized the TriNetX database, a large-scale platform providing access to deidentified electronic medical records from over 130 million patients across 94 healthcare organizations in the United States. The study included patients diagnosed with metastatic HCC (ICD-10 codes: C22, C22.8) who were aged 18 years or older, diagnosed between January 2019 and October 2024, and had received first-line chemotherapy with atezolizumab and bevacizumab. The cohort was divided into two groups: one receiving lenvatinib and the other cabozantinib as second-line therapy. The primary outcome was overall survival (OS), compared between the two treatment groups using 1:1 propensity score matching (PSM) to balance baseline demographics and comorbidities. Kaplan-Meier survival analysis, log-rank tests, and hazard ratios (HR) were employed to assess differences in OS. Results: Between January 2019 and October 2024, a total of 552 patients met the study criteria, including 397 patients who received Lenvatinib and 155 patients who received cabozantinib as second-line therapy. Median age was similar in two groups (65.2 vs 65.9 yrs). There were no differences between the two groups with respect to gender, albumin or bilirubin levels. Lenvatinib group had lower proportions of white patients (44.1% vs 55.3%). After PSM (matched on age, race, gender, albumin and bilirubin), the final analysis included 151 patients in each treatment group. Kaplan-Meier survival curves demonstrated no statistically significant difference in OS between the two groups (median OS: 16.6 vs 10.9 months; HR: 0.809; 95%CI: 0.576-1.136; p=0.597). Conclusions: This retrospective cohort study found no significant difference in OS in pts with metastatic HCC treated with lenvatinib or cabozantinib as second-line therapy following atezolizumab plus bevacizumab. These findings suggest that both agents may offer comparable survival benefits, highlighting the need for further prospective studies to refine second-line treatment strategies for advanced HCC.

PURPOSE Limited treatment options exist for patients with locally advanced or metastatic biliary tract cancers (BTCs). Recently, several clinical trials provided preliminary evidence for human epidermal growth factor receptor 2 (HER2) as a new target for patients with HER2-expressing BTC. We conducted a systematic review and pooled analysis of the safety and efficacy of anti-HER2 agents in patients with advanced BTCs. METHODS A comprehensive search of PubMed/MEDLINE and EMBASE was performed to identify phase I, II, or III clinical trials published between January 2019 and March 2024 that evaluated anti-HER2 therapy in locally advanced or metastatic BTC. Participant data included in the analysis were from trials evaluating the efficacy and safety of various anti-HER2 agents. The primary end points included objective response rate (ORR), disease control rate (DCR), and progression-free survival (PFS). The secondary end points included incidence of treatment-related adverse events (TRAEs), rate of treatment discontinuation, and death. RESULTS The analysis included 368 patients from eight publications diagnosed with advanced BTC. Patients were treated with several anti-HER2 agents including zanidatamab, pertuzumab plus trastuzumab, tucatinib plus trastuzumab, trastuzumab deruxtecan, trastuzumab plus chemotherapy, trastuzumab-pkrb plus chemotherapy, and neratinib. The pooled ORR and DCR were 34% (95% CI, 24 to 44) and 64% (95% CI, 51 to 77), respectively. The pooled weighted PFS and median overall survival were 4.8 and 9.4 months, respectively. The pooled duration of response for the reporting trials was 5.0 months. In the study cohort, 82.6% of patients experienced any adverse event and 32.1% experienced a grade 3-4 adverse event. Only 5.7% of the patients discontinued treatment secondary to TRAEs. CONCLUSION In patients with HER2-expressing BTCs, anti-HER2 therapies are viable options, particularly in the second-line setting.

Abstract Background Impact of BRAF V600E mutations (BRAFV600E), a poor prognostic factor in metastatic colorectal cancer, is lacking in non-CRC gastrointestinal (GI) cancers including pancreatic (PDAC), gastric/gastroesophageal (GEA), hepatocellular carcinoma (HCC), and cholangiocarcinoma (CCA). Due to tumor-agnostic approvals for patients with BRAFV600E, understanding the frequency and impact of BRAF alterations across non-CRC GI cancers is essential for clinical decision-making. Methods Patients with PDAC, GEA, HCC, or CCA who had cell-free DNA detected on Guardant360 (Guardant Health) from 2020 to 2023 were queried. Prevalence of characterized BRAF genomic alterations (GA) was calculated; GAs were grouped by class (Class I/II/III). The Chi-squared test assessed differences between cancer types. A subset of patients had outcomes analysis using GuardantINFORM, a real-world clinicogenomic database, to derive real-world overall survival (rwOS). Results Of 32 480 included patients, BRAF GAs were identified in 4.4%; 19% were BRAFV600E (0.81% prevalence overall). CCA had the highest rate of BRAF GAs and BRAFV600E (P &lt; .01); HCC and GEA had the highest rates of BRAF class II/III alterations. There were no significant differences in rwOS by alteration class or cancer type; numeric differences were observed by alteration class. Few patients were treated with BRAF inhibitors (2.2%). Prevalence of co-occurring alterations was unique by cancer type. Conclusions Frequency of BRAF GAs, including BRAFV600E, in non-CRC GI cancers detected by liquid biopsy is similar to tissue-based rates and can be reliably used to assess BRAF status. BRAF GAs have mixed prognostic implications on survival for patients with non-CRC GI malignancies that warrant further exploration.

PURPOSE Immune checkpoint inhibitors (ICIs) have significantly improved outcomes in various malignancies. However, the high cost of these therapies limits access for much of the global population. This systematic review aims to evaluate the efficacy of low-dose ICIs compared with standard doses in different malignancies, addressing financial and access barriers in global cancer care. METHODS We conducted a systematic review of studies comparing the efficacy of low-dose versus standard-dose ICI regimens in advanced solid tumors. A comprehensive search was performed across multiple electronic databases, including retrospective and prospective studies. Excluded were animal studies, editorials, conference papers, book chapters, and other immunotherapy modalities. Outcomes assessed included overall survival (OS), progression-free survival, and objective response rate. Results were summarized descriptively due to study heterogeneity. RESULTS From 1,010 screened articles, four studies with 435 Asian patients were included, covering a variety of solid tumors. All included studies were with a low quality of evidence and a high risk of bias due to retrospective design. Two studies used weight-based dosing (pembrolizumab <2 mg/kg and nivolumab <2.15 mg/kg), showing similar OS to standard dosing in non–small cell lung cancer (NSCLC) and renal cell carcinoma, respectively. Flat dose regimens in two studies (nivolumab 20 mg or 100 mg once every 3 weeks and pembrolizumab 100 mg once every 3 weeks) also demonstrated comparable OS in NSCLC. CONCLUSION Low-dose ICIs may offer equivalent clinical benefits to standard dosing, potentially reducing costs and expanding access in developing countries. Although awaiting more representative randomized clinical trials, weight-based ICI regimens could be a viable alternative in low- and middle-income countries.

639 Background: Limited treatment options exist for patients with locally advanced or metastatic biliary tract cancers (BTCs). Recently, several clinical trials provided preliminary evidence for human epidermal growth factor receptor-2 (HER2) as a new target for patients with HER2 expressing BTC. We conducted a systematic review and pooled analysis of the safety and efficacy of anti-HER2 agents in patients with advanced BTC. Methods: A comprehensive search of PubMed/MEDLINE and EMBASE was performed to identify phase 1, 2, or 3 clinical trials published between January 2019 and March 2024 that evaluated anti-HER2 therapy in locally advanced or metastatic BTC. Primary endpoints included objective response rate (ORR), disease control rate (DCR), and progression-free survival (PFS). Secondary endpoints included the incidence of treatment-related adverse events (TRAEs), rate of treatment discontinuation, and death. Forest plots were generated to summarize the results and demonstrate the effect size estimates for each study, along with their confidence intervals and the pooled estimate from the random-effects model. The random-effects models were configured to use the Restricted Maximum Likelihood method for estimating between-study variance for all analyses. Results: After excluding duplicate and irrelevant articles, data extraction and analysis were performed on eight selected clinical trials. The analysis included 368 patients with a median age of 64 (range 49-68), with 55% being female. Patients were treated with several anti-HER2 agents, including zanidatamab, pertuzumab plus trastuzumab, tucatinib plus trastuzumab, trastuzumab deruxtecan, trastuzumab plus chemotherapy, trastuzumab-pkrb plus chemotherapy and neratinib. The pooled ORR and DCR were 34% (95% CI 24-44) and 64% (95% CI 51-77) respectively. The pooled weighted PFS and median OS survival were 4.8 and 9.4 months, respectively. The pooled duration of response was 5.0 months. In our subset analysis, which included only patients who had received ≥1 prior therapy, the pooled ORR was 30% (95% CI 22-39), the pooled DCR was 62% (95% CI 48-75), and the pooled median PFS was 4.4 months. In the study cohort, 82.6% of patients experienced any adverse event, and 32.1% experienced a grade 3-4 adverse event. Only 5.7% of the patients discontinued treatment secondary to TRAEs. Conclusions: In patients with HER2 expressing BTCs, anti-HER2 therapies demonstrated preliminary signals of efficacy with manageable toxicities, particularly in the second-line setting.

Colorectal cancer (CRC) represents a heterogeneous group of diseases that imposes a considerable global and national health burden. Although most CRC patients are diagnosed at an early stage and undergo potentially curative treatment, a significant proportion experience recurrence. Currently, adjuvant chemotherapy decisions are primarily based on clinicopathological characteristics, which have well-recognized limitations in accurately identifying patients harboring minimal residual disease (MRD), often resulting in unnecessary chemotherapy exposure. Circulating tumor DNA (ctDNA) has emerged as a promising surrogate marker for MRD, offering a more precise approach to identifying patients at risk of recurrence after curative-intent surgery and refining adjuvant chemotherapy decisions. Growing evidence from multiple studies has demonstrated that ctDNA outperforms traditional clinicopathological factors as a marker for MRD. This review synthesizes key studies supporting the role of ctDNA in MRD detection for CRC patients and evaluates clinical trials investigating the application of ctDNA in guiding adjuvant therapy decisions. This emerging strategy holds the potential to transform the adjuvant treatment paradigm in colorectal cancer by optimizing therapeutic precision and minimizing unnecessary treatment.

50 Background: A+B is commonly used as first line systemic therapy in HCC patients with CP-B liver function, although in the IMbrave150 clinical trial, its efficacy was only assessed in patients with CP-A liver function. We evaluated outcomes in patients with CP-B liver function and compared to those with CP-A. Methods: We completed a multi-institution, retrospective review of patients with HCC from Mayo Clinic and University Hospitals Seidman Cancer Center, who had received A+B in the first line setting between March 2018 and November 2023. CP score was calculated at time of treatment, response was assessed, and progression free (PFS) and overall (OS) survival were determined using the Kaplan Meier method. Results: Among 322 patients with HCC, median age was 66.5 years, 78.6% were male, and 82.6% were white. Eighty-six patients (27%) had CP-B liver function, while 226 (70%) had CP-A and 10 (3%) had CP-C. Etiology of liver disease in patients with CP-B included hepatitis B in 7.0%, hepatitis C in 38.4%, alcohol use in 30.2%, and metabolic associated steatohepatitis in 20.9%. Median OS in patients with CP-B liver function was 6.4 months, while mOS was 21.6 months for those with CP-A ( p<0.0001). Further stratifying, mOS in those with CP-B7 was 9.1 months, CP-B8 was 5.5 months, and CP-B9 was 4.0 months. 12-month OS in patients with CP-B was 32.4%, compared to 69.3% in CP-A. Median PFS was 4.8 months in those with CP-B and 8.9 months in those with CP-A. Median PFS in those with CP-B7, -B8, and -B9 was 6.4 months, 2.7 months, and 2.7 months, respectively. Among those with CP-B, 1 patient had a complete response, 17 (19.8%) had a partial response, 29 (33.7%) had stable disease, and 37 (43.0%) had progressive disease. Adverse events in CP-B patients included hypertension in 14.0% (grade 3 in 1 patient), bleeding in 16.3% (grade 3 or greater in 11.6%), fatigue in 38.4%, and an immune-related adverse event in 17.4% (grade 3 in 5.8%). Conclusions: Patients with advanced HCC and CP-B7 liver function may still benefit from A+B. Importantly, no additional safety risks were identified in this subgroup. Those with CP-B8 and CP-B9 have significantly worse survival than those with CP-B7 and the likelihood of benefit from systemic therapy is minimal. It is important for providers to address the impact of baseline liver function on expected outcomes in patient with HCC.