Fernandes, B C

e15598 Background: Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape of gastrointestinal (GI) malignancies. Emerging evidence suggests that gut microbiome composition plays a critical role in modulating the efficacy of immunotherapy. Antibiotics, by disrupting intestinal microbial diversity, may attenuate antitumor immune responses and compromise ICI outcomes. We evaluated time-dependent clinical outcomes associated with antibiotic exposure using real-world data. Methods: We conducted a retrospective cohort study using a large federated real-world database (2015-2025). Adults (18–89 years) with gastrointestinal or hepatobiliary malignancies (including colorectal, gastric, esophageal, and liver cancers) treated with ICI, receiving systemic antibiotics, were compared with matched controls without antibiotic exposure. Cohorts were balanced using 1:1 Propensity score matching for demographics, comorbidities, and treatment variables. The primary outcome was all-cause mortality at 30 days of ICI initiation; the secondary outcomes were hospitalization secondary to infectious and organ-related complications, overall survival at 1 and 3 years. Pre-specified subgroup analyses were performed in older adults ( > / = 65 years). Effect estimates were reported as risk ratios( RR), hazard ratios (HR), and absolute risk differences. Survival was analyzed using Kaplan–Meier curves and Cox proportional hazards models. Results: Within 30 days, antibiotic exposure was associated with significantly increased risks of Clostridioides difficile infection (RR 2.39), pneumonia (RR 2.93), acute kidney injury (RR 1.40), acute respiratory failure (RR 2.11), and neutropenia (RR 1.18) (all p < 0.05). Absolute risk differences translated to a number needed to harm (NNH) of approximately 38 for pneumonia, 143 for acute kidney injury, and ~140 for C. difficile infection. One-month mortality was modestly higher in the antibiotic group (5.4% vs 4.5%; HR 1.22; p = 0.014). However, no significant differences in mortality were observed at 6 months, 1 year, or 3 years, and survival curves converged over time. In the subgroup analysis of adults ≥65 years, early adverse event patterns were preserved, while long-term mortality remained unchanged. One-year hospital admission rates did not differ significantly between groups. Conclusions: Antibiotic exposure is associated with substantial early infectious and organ-related harm and a small increase in short-term mortality, without improvement in long-term survival, including among older adults. These findings highlight a critical opportunity for risk-adapted antibiotic stewardship and careful reassessment of empiric antibiotic use. Key words: ICI- Immune checkpoint inhibitors, RR- Risk ratio, HR- Hazard Ratio, NNH- Number Needed to Harm.

8075 Background: The role of definitive local thoracic therapy in metastatic non–small cell lung cancer (NSCLC) remains controversial. While stereotactic body radiation therapy (SBRT) is increasingly utilized, comparative survival outcomes with surgical resection in real-world populations remain limited. We evaluated survival and pulmonary outcomes associated with surgery versus SBRT in patients with stage IV NSCLC. Methods: We conducted a retrospective cohort study using the TriNetX Research Network including adults (≥18 years) with stage IV NSCLC treated between January 2013 and December 2023 who underwent definitive local thoracic therapy with either surgical resection or SBRT. Patients with small cell lung cancer, prior lung cancer diagnoses, prior thoracic radiation, or incomplete survival data were excluded. Propensity score matching (1:1) was performed to balance demographics, comorbidities, smoking history, and exposure to systemic therapy including chemotherapy and immunotherapy within 6 months of index treatment. Primary outcomes included landmark 1-year all-cause mortality and overall survival. Secondary outcomes included pneumonia and respiratory failure. Kaplan–Meier analysis and Cox proportional hazards regression were performed. Results: After matching, 1,934 patients were included (967 per cohort). At 1 year, surgical resection was associated with significantly lower mortality compared with SBRT (17.5% vs 31.4%; RR 0.56, 95% CI 0.47–0.66; p < 0.001), corresponding to an absolute risk reduction of 13.9% and an estimated number needed to treat of approximately 7. Kaplan–Meier analysis demonstrated superior survival in the surgical cohort (log-rank p < 0.001). Surgical resection remained associated with significantly improved long-term survival, with a 64% lower hazard of death (HR 0.36, 95% CI 0.30–0.44; p < 0.001) and prolonged median survival (3,942 vs 1,182 days). Pulmonary outcomes favored surgery. Pneumonia incidence was significantly lower in the surgical cohort at both 1 year (12.9% vs 29.3%; RR 0.44; p < 0.001) and 3 years (5.9% vs 14.2%; RR 0.42; p < 0.001). Rates of respiratory failure did not differ significantly between treatment groups. Conclusions: In this large real-world propensity-matched study, surgical resection was associated with significantly improved survival compared with SBRT in carefully selected patients with stage IV NSCLC. Surgery was additionally associated with lower long-term pulmonary infectious complications without increased respiratory failure risk. These findings suggest a potential role for aggressive local therapy in selected metastatic patients and support prospective trials to refine patient selection strategies.

3605 Background: Metabolic status and systemic inflammation are increasingly recognized as important modifiers of immune checkpoint inhibitor (ICI) response. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) exhibit anti-inflammatory and immunomodulatory properties and are widely used in diabetes and obesity. However, their clinical impact on immunotherapy outcomes in metastatic colorectal cancer (mCRC) remains unclear. Methods: We conducted a retrospective observational cohort study using the TriNetX Global Collaborative Network, including electronic health records from 170 healthcare organizations between 2015 and 2025. Adults with mCRC who received at least one ICI were identified. Patients prescribed GLP-1 RAs within six months before or after ICI initiation were compared with non-exposed controls. Patients with prior bariatric surgery were excluded. Cohorts were balanced using 1:1 propensity score matching for demographics, metabolic conditions, and major comorbidities. Primary endpoint was all-cause mortality at 1, 3, and 5 years. Secondary outcomes included pneumonia, heart failure exacerbation, and major abdominal surgical procedures. Survival analyses were performed using Kaplan–Meier methods and Cox proportional hazards models. Results: Among 8,304 eligible patients, 148 received GLP-1 RAs. After propensity matching, 138 patients were included in each cohort with well-balanced baseline characteristics. At 1 year, mortality was lower in the GLP-1 cohort (27.5% vs 40.6%), corresponding to a 32% relative risk reduction (RR 0.68, 95% CI 0.49–0.95) and reduced hazard of death (HR 0.67, 95% CI 0.43–1.03). This association persisted at 3 years (27.5% vs 41.3%; RR 0.67, 95% CI 0.48–0.93; HR 0.68, 95% CI 0.45–1.05) and 5 years (28.3% vs 42.0%; RR 0.67, 95% CI 0.49–0.93), with higher 5-year survival probability (50.5% vs 41.5%). Secondary outcomes favored GLP-1 exposure, including lower incidence of pneumonia (10.9% vs 17.4%; HR 0.58) and fewer heart failure exacerbations (23.9% vs 31.9%; HR 0.75). Rates of major abdominal surgical procedures were numerically lower in the GLP-1 cohort. Conclusions: In this large real-world cohort, concurrent GLP-1 RA exposure was associated with clinically meaningful and durable survival benefit in mCRC patients receiving ICIs, without increased adverse clinical outcomes. These findings suggest a potential immunometabolic interaction and support prospective evaluation of GLP-1–based strategies as adjunctive modifiers of immunotherapy response.

Abstract Purpose This analysis aims to provide a comprehensive overview of lung transplantation trends in the United States from January 1, 1988, through January 31, 2025. By examining key variables such as recipient ABO blood group, donor type (deceased or living), demographic factors, and geographic distribution, the goal is to highlight the evolution and current state of lung transplantation practices. Methods Data were obtained from the Organ Procurement and Transplantation Network (OPTN), encompassing all reported lung transplants during the specified time period. Relevant metrics included the number of transplants per year, recipient characteristics (blood type, race/ethnicity, gender, and age), donor type (deceased versus living), and state-level transplant volumes. Simple descriptive statistics (e.g., frequencies and percentages) were used to identify trends and capture the distribution of transplants among different demographic groups and geographic regions. Results A total of 55,435 lung transplants were performed in the United States between 1988 and early 2025. The vast majority (over 99%) utilized deceased donors, underscoring the limited role of living-donor lobar transplantation, with only 253 procedures reported nationally. Among recipients, ABO blood group O was the most common (∼45%), followed by group A (∼40%), group B (∼11%), and group AB (∼4%). Male recipients represented approximately 57% of transplants, while females accounted for 43%. Regarding race/ethnicity, White non-Hispanic patients constituted roughly 80% of all recipients, with Black non-Hispanic (8%) and Hispanic/Latino (8%) recipients forming smaller but significant proportions. Age distribution data revealed that individuals aged 50 to 64 years received nearly half of all lung transplants, and those over 65 years composed about a quarter of total recipients, reflecting a gradual shift in acceptance criteria favoring older adults. Geographically, California reported the highest volume of lung transplants, attributable to its large population and multiple high-volume transplant centers, while other states such as Florida, Ohio, North Carolina, and Missouri also demonstrated notable activity. Conclusion Lung transplantation in the United States has witnessed substantial expansion in both volume and scope since 1988, with the majority of procedures involving deceased donor lungs. A small number of living-donor lung transplants, while demonstrating innovative clinical possibilities, remains limited. The demographic profile of recipients continues to shift, evidenced by a growing proportion of older adults and a predominance of ABO type O and White, non-Hispanic recipients. Despite these advancements, persistent gaps in access, particularly among underrepresented racial and ethnic groups, highlight the need for further refinement in organ allocation policies and broader support services. This abstract is funded by: None

Abstract Purpose This study aimed to analyze mortality trends among patients with pneumonia and chronic kidney disease in the United States from 1999 to 2020. By examining patterns across urbanization levels, racial and ethnic groups, geographic regions, and sex, the study sought to identify significant changes over time and potential disparities in mortality outcomes. Methods Mortality data were extracted from the CDC WONDER database for patients diagnosed with pneumonia (ICD-10: J09-J18) and chronic kidney disease (ICD-10: N18). Trends were analyzed using Annual Percent Change (APC) with 95% confidence intervals (CI). Joinpoint regression was utilized to identify significant shifts in mortality trends over time. The analysis was stratified by urbanization level (Large Central Metro, Large Fringe Metro, Medium Metro, Small Metro, Micropolitan), ethnicity (American Indian or Alaska Native, Asian or Pacific Islander, Black or African American, White), census region (Northeast, Midwest, South, West), Hispanic origin (Hispanic or Latino, Not Hispanic or Latino), and sex (Female, Male). Results From 2018 to 2020, significant increases in mortality were observed across all demographic and geographic categories. Urban areas, particularly Large Central Metro (APC = 39.4026%, p = 0.0008) and Small Metro (APC = 37.0284%, p = 0.0004), experienced the most pronounced rises. Ethnic disparities were evident, with Black or African American (APC = 49.9199%, p &lt; 0.000001) and Hispanic or Latino (APC = 61.5742%, p &lt; 0.000001) populations showing the highest mortality increases. By census region, the Midwest (APC = 35.7843%, p = 0.0004) and South (APC = 34.7972%, p = 0.0016) had the most significant spikes. Both females (APC = 36.0664%, p = 0.0004) and males (APC = 35.1504%, p &lt; 0.000001) experienced substantial mortality increases, with females showing slightly higher rates. Conclusion The findings reveal significant increases in mortality from 2018 to 2020 across all analyzed categories, with notable disparities among racial, ethnic, and geographic groups. These trends highlight the need for further investigation into underlying causes and targeted interventions to address inequities. Clinical implications The results underscore the importance of addressing disparities in healthcare access and outcomes, particularly for Black or African American and Hispanic or Latino populations. Clinicians should focus on early diagnosis, effective management of comorbidities, and equitable resource distribution to mitigate mortality risks in high-risk groups. This abstract is funded by: None