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TPS11592 Background: Epithelioid hemangioendothelioma (EHE) is an ultra-rare vascular sarcoma with about 120 cases diagnosed in the US per year. Although it is commonly considered an indolent disease, in its aggressive form clinical outcomes are poor. Molecularly, EHE is characterized by the presence of oncogenic fusions with HIPPO pathway effectors TAZ or YAP; TAZ-CAMTA1 or YAP-TFE3. YAP/TAZ are modulators of mTORC1 in preclinical models, suggesting that mTOR inhibition may be an effective treatment mechanism for EHE. Nab-sirolimus is albumin bound sirolimus, which achieves higher intratumoral accumulation compared to oral sirolimus and has demonstrated increased antitumor activity in preclinical cancer models compared to the oral mTOR inhibitors sirolimus and everolimus. This is an open label, multi-center, single arm, phase II clinical trial with a two-stage design, testing nab-sirolimus for progressing or symptomatic EHE. The primary objective is to determine ORR of nab-sirolimus in patients with EHE who require systemic treatment. We hypothesize that nab-sirolimus will have significant clinical efficacy for EHE as measured by the primary endpoint of objective response rate, as well as by secondary outcomes including progression free survival benefit over historical controls and by improvement in patient reported outcomes (PROs). If positive, this trial could lead to a new standard of care for treating EHE. Methods: This is a single arm, multi-center, phase 2 study with a two-stage design. Key inclusion criteria include histologically or cytologically confirmed EHE that is either progressing or clinically symptomatic, not a candidate for curative intent surgery, and requires systemic therapy in the opinion of the investigator, radiographically evaluable disease by RECIST v1.1, age ≥18 years, ECOG performance status ≤ 2, and adequate end organ function. With a Simon two-stage optimal design with one sided alpha 0.10, power 90%, assuming a historical control ORR 5% to detect an ORR of 20% (alternative hypothesis), 12 patients will be included in the first stage. If there is ≥ 1 response, an additional 25 patients will be enrolled to a total of 37 patients. ≥ 4 responses are needed for a significant result. The total planned accrual is 41 patients to account for unevaluable patients who may be enrolled, 10% above the required evaluable patients. Planned post hoc subgroup analyses will include outcomes by fusion type and presence of serosal effusions at the time of study enrollment. The trial is registered at clinicaltrials.gov NCT07104331. Clinical trial information: NCT07104331 .

e23089 Background: Sodium–glucose cotransporter-2 (SGLT2) inhibitors are increasingly used for glycemic and cardiovascular benefits; however, concerns persist regarding genitourinary infections, particularly in vulnerable populations such as patients with cancer and diabetes. Real-world data evaluating the safety of SGLT2 inhibitors in this population remain limited. We evaluated the association between SGLT2 inhibitor use and genitourinary infection risk among cancer patients with type 2 diabetes. Methods: We conducted a retrospective cohort study using the TriNetX federated research network. Adult patients (≥18 years) with malignant neoplasms and type 2 diabetes mellitus were identified. Patients were stratified based on exposure to SGLT2 inhibitors and compared with cancer patients with diabetes not receiving SGLT2 inhibitors. Primary outcomes included urinary tract infection (UTI) and cystitis, identified using ICD-10 diagnostic codes. Analyses included unadjusted comparisons, 1:1 propensity score matching (PSM), and a Cox proportional hazards model as a sensitivity analysis to assess time to first UTI within one year following index exposure. Results: A total of 7,485 patients were included (7,137 without SGLT2 inhibitors and 348 with SGLT2 inhibitors). In unadjusted analyses, crude rates of UTI and cystitis were numerically higher in the SGLT2 inhibitor cohort. After 1:1 propensity score matching (312 patients per cohort), baseline characteristics were well balanced. The incidence of UTI was identical between matched cohorts (6.41% vs 6.41%, p = 1.00), with no significant differences observed for cystitis or acute cystitis. In a Cox proportional hazards sensitivity analysis, SGLT2 inhibitor use was associated with a significantly lower hazard of UTI compared with no SGLT2 inhibitor exposure (hazard ratio 0.68, 95% confidence interval 0.52–0.89; p = 0.0048). Conclusions: In this large real-world cohort of cancer patients with diabetes, SGLT2 inhibitor use was not associated with an increased risk of genitourinary infections. Propensity-matched analyses demonstrated no difference in absolute infection risk, while time-to-event analysis suggested a lower hazard of UTI among patients receiving SGLT2 inhibitors. These findings support the genitourinary safety of SGLT2 inhibitors in cancer patients with diabetes and may inform clinical decision-making in this high risk population.

e19046 Background: While outcomes in pts with R/R FL have improved with current SOC treatments (Tx), there remains a need for safe, efficacious, and convenient Tx options. GOLCA is a potential, first-in-class, oral CELMoD designed for Tx of lymphoma, with preferential distribution to lymphoid organs and enhanced activity in lymphoma cell lines. GOLCA induces rapid and deep degradation of Ikaros and Aiolos, leading to direct cell killing and immunomodulatory activity. GOLCA + R was well tolerated and effective in heavily pretreated pts in the two-part Ph 1/2 study, CC-99282-NHL-001. Here, we provide longer f/u in pts with R/R FL from Part B of the study. Methods: Pts with R/R FL with ≥2 prior lines of Tx (≥1 if prior anti-CD20 Tx) received GOLCA orally, once daily at 0.2 mg (n=22) or 0.4 mg (n=38) ± R for up to 2 y or until progressive disease (PD)/unacceptable toxicity. Primary endpoints included safety and RP2D determination; secondary endpoints are preliminary efficacy and PK. Results: As of September 15, 2025, 60 pts were enrolled. In 0.2 and 0.4 mg groups, median prior Tx lines were 3 and 3, 32% and 32% had prior lenalidomide (LEN), 27% and 29% had prior T-cell–redirecting Tx (CAR T and/or bispecific antibody) and 32% and 32% were refractory to last regimen. Tx is ongoing in 6 (27%) and 17 (45%) pts at 0.2 and 0.4 mg, respectively; discontinuations (d/c) were mostly due to PD. Neutropenia, an on-target side effect of GOLCA, was the most common grade 3/4 Tx-emergent adverse event (TEAE) occurring in 59% and 68% of pts at 0.2 and 0.4 mg, followed by anemia (9% and 16%) and febrile neutropenia (9% and 8%). Median time to resolution of neutropenia was 8 days. Dose reductions occurred in 14% and 37% of pts at 0.2 and 0.4 mg, most commonly due to neutropenia (5% and 21%) and febrile neutropenia (5% and 5%). No d/c or deaths were from GOLCA-related TEAEs. Non-hematologic TEAEs were infrequent and mostly low grade. In efficacy-evaluable pts (GOLCA 0.2 and 0.4 mg + R, n=22 and n=36), median f/u was 14.03 months (mo), overall response rate (ORR) was 77% (complete response rate [CRR], 41%) at 0.2 mg, and 97% (CRR, 78%) at 0.4 mg. In the 0.4 mg group, responses were consistent in high-risk subsets including pts with prior LEN (ORR, 100%; CRR, 75%) and/or T-cell–redirecting Tx (ORR, 91%; CRR, 64%). GOLCA 0.4 mg + R demonstrated durable responses (median DOR, 9.17 mo; 91% of pts who achieved a CR remained in CR at cutoff). Conclusions: With longer f/u, GOLCA + R demonstrated promising efficacy with durable responses and no new safety signals. The 0.4 mg group had higher ORR and CRR than 0.2 mg, including in pts with prior LEN-based and/or T-cell–redirecting Tx, with a manageable safety profile at both doses. The results support the development of GOLCA + R as a fixed-duration, chemotherapy-free outpatient Tx in the Ph 3 GOLSEEK-4 study in 2L+ FL (NCT06911502). Clinical trial information: NCT03930953 .

e16598 Background: Brain metastases occur in a substantial proportion of patients with renal cell carcinoma (RCC) and are associated with poor prognosis. Stereotactic radiosurgery (SRS) is frequently used for intracranial disease control; however, contemporary real-world survival outcomes and the influence of systemic therapy exposure and metastatic burden remain incompletely characterized. Methods: We conducted a retrospective observational study using the TriNetX global federated health research network. Adult patients (≥18 years) with RCC and documented brain metastases who underwent stereotactic radiosurgery between January 2013 and December 2023 were identified. The index date was defined as the date of first SRS. Baseline demographics, comorbidities, and prior systemic therapy exposure including immune checkpoint inhibitors and VEGF-targeted therapies within 6 months before SRS were assessed. Metastatic burden was approximated using the number of distinct extracranial metastatic organ sites (single-organ vs multi-organ involvement). Overall survival (OS) was evaluated using Kaplan–Meier methods. Results: A total of 232 patients with RCC and brain metastases treated with SRS were included. Mean age was 61.2 ± 10.6 years, and 72% were male. Common comorbidities included hypertension (53%), diabetes mellitus (30%), chronic kidney disease (28%), and cerebrovascular disease (26%). Prior to SRS, 78% of patients received systemic therapy, including immune checkpoint inhibitors (49%) and VEGF-targeted therapies (46%). Using organ-site count as a proxy for disease burden, 59% demonstrated single-organ extracranial metastatic involvement. During follow-up, 95 patients (40.9%) experienced all-cause mortality. Median overall survival was 967 days (31.8 months). Estimated long-term survival probability at maximum follow-up was 21.2%. Kaplan–Meier analysis demonstrated early survival attrition followed by prolonged survival in a subset of patients. Patients receiving immunotherapy and those with limited extracranial metastatic burden demonstrated more favorable survival patterns. Conclusions: In this large contemporary real-world cohort of RCC patients with brain metastases treated with stereotactic radiosurgery, median overall survival exceeded 2.5 years, providing important modern survival benchmarks. Favorable outcomes were observed among patients receiving systemic immunotherapy and those with limited metastatic burden, supporting the continued role of SRS within multidisciplinary management strategies for selected patients with metastatic RCC.

e16469 Background: Pancreatic cancer remains among the most lethal malignancies worldwide, with limited improvement in survival despite therapeutic advances. Contemporary real-world data characterizing recent diagnosis acceleration, demographic disparities, and future burden remain limited. We evaluated national trends in pancreatic cancer burden using a large federated electronic health record (EHR) network. Methods: We conducted a retrospective multicenter real-world cohort analysis using the TriNetX Research Network. Adult patients (≥18 years) with pancreatic cancer were identified using ICD-10-CM code C25. Annual newly recorded diagnosis proportions, prevalence, and incidence rates were calculated for calendar years 2020–2024 and stratified by age, sex, race, and ethnicity. New diagnoses were defined as first recorded pancreatic cancer encounters within each calendar year. Exploratory future burden projections were generated through 2028 using autoregressive integrated moving average (ARIMA) time-series modeling. Results: Between 2020 and 2024, newly recorded pancreatic cancer diagnoses increased from 0.032% (21,118 cases) to 0.046% (23,660 cases), representing a descriptive relative increase exceeding 40%. Prevalence increased from 0.101% (65,971 cases) to 0.145% (74,139 cases), reflecting rapid expansion of disease burden. Diagnosis burden increased markedly with advancing age, with the highest burden observed among individuals aged ≥65 years. Males consistently demonstrated higher diagnosis proportions compared with females. Racial stratification demonstrated higher recorded diagnosis proportions among White and Asian populations, while substantial prevalence burden persisted across all racial groups, potentially reflecting differences in healthcare utilization and access. Non-Hispanic individuals exhibited higher diagnosis and prevalence proportions compared with Hispanic individuals. Exploratory ARIMA forecasting projected continued growth in pancreatic cancer burden through 2028, with widening uncertainty intervals over time, indicating escalating long-term healthcare demand. Conclusions: Pancreatic cancer burden in the United States is rapidly increasing, with disproportionate impact among older adults and males and persistent demographic disparities. Exploratory projection modeling suggests continued expansion of disease burden in the near term. These findings highlight the urgent need for earlier detection initiatives, risk-adapted screening strategies, and healthcare system preparedness to address the growing national impact of pancreatic cancer.

e16322 Background: Small intestine neuroendocrine carcinoma (NEC) is a rare, aggressive malignancy comprising less than 0.1% of gastrointestinal cancers. Population-level data remain limited, restricting understanding of long-term survival patterns, demographic disparities, and evolving disease burden. We evaluated survival outcomes, demographic predictors, and incidence trends of small intestine NEC in the United States. Methods: We conducted a retrospective population-based cohort study using SEER Research Data (17 registries, November 2024 submission). Patients diagnosed with malignant small intestine NEC (ICD-O-3 morphology code 9.3.3.1.2) between 2000 and 2022 were identified using SEER*Stat (v9.0.4.2). Variables including age group, sex, race, year of diagnosis, survival time, and vital status were analyzed in R (v4.5.1). Overall survival (OS) was estimated using Kaplan–Meier methods and compared using log-rank testing. Cox proportional hazards models identified independent predictors of OS. Annual case counts were modeled using time-series forecasting to project future incidence. Results: A total of 506 patients were included. Estimated OS was 94.4% (95% CI 92.4–96.4) at 1 year, 88.1% (85.3–91.0) at 3 years, and 82.4% (79.0–85.9) at 5 years, with a subset demonstrating survival beyond 15 years. Increasing age was associated with worse survival (log-rank p = 0.058). Significant racial differences in OS were observed (log-rank p < 0.0001). In multivariable analysis, race remained independently associated with OS. Incidence forecasting projected a modest increase in annual case burden over the next decade. Conclusions: Small intestine NEC demonstrates heterogeneous survival outcomes, significant demographic disparities, and projected growth in disease burden. These findings highlight the need for improved risk stratification, equitable access to care, and integration of molecular and treatment-level data to optimize management of this rare malignancy

e16246 Background: First line systemic therapy for advanced hepatocellular carcinoma (HCC) includes immune checkpoint inhibitor (ICI) combination therapy, with tyrosine kinase inhibitors (TKIs), lenvatinib or cabozantinib, commonly used as second line therapy. However, there is limited data comparing efficacy of TKIs following first line ICI therapy. In the present study, we compared survival and risk of hospitalization in a propensity score matched analysis of patients who received lenvatinib or cabozantinib following progression on first line ICI therapy in patients with advanced HCC. Methods: We performed a retrospective cohort study using data from TriNetX, a healthcare database of over 150 million patients in the United States. We identified adult patients with a history of HCC who received atezolizumab plus bevacizumab (A+B) or durvalumab plus tremelimumab (D+T) as first line treatment. We then stratified patients by use of lenvatinib or cabozantinib in the subsequent line setting. Propensity score matching (PSM) was conducted between those who received lenvatinib and those who received cabozantinib, matching for demographic factors (age, sex, race), clinical characteristics (history of alcohol use, ascites, esophageal varices, or viral hepatitis), and laboratory parameters [platelets, albumin, bilirubin, INR and alpha-1-fetoprotein (AFP)]. Results: We identified 416 patients who were initially treated with either A+B or D+T, with 327 patients receiving A+B and 89 patients receiving D+T. Of these, 336 patients (80.8%) subsequently received lenvatinib and 80 patients (19.2%) received cabozantinib. Baseline characteristics of demographic factors, clinical characteristics, and laboratory parameters were comparable between patients in the lenvatinib arm and cabozantinib arm with all standardized mean differences (SMD) < 0.10. After PSM, 76 patients were included in the analyses, with all variables adequately balanced. There was no significant difference in the risk of hospitalization between those receiving lenvatinib or cabozantinib at 3 months [31.6% vs 34%, odds ratio (OR) 1.13, 95% confidence interval (CI) 0.57-2.2]. There was also no significant difference in mOS between those receiving lenvatinib and cabozantinib [9.5 vs 9.0 months, hazard ratio (HR) 1.03, 95% CI 0.62-1.7]. Conclusions: In patients with HCC who received lenvatinib or cabozantinib as second-line therapy following first-line ICI combination therapy, we found no significant differences in rate of hospitalization or survival. These findings suggest that either option may be appropriate, and decisions may be based in side effect profile and patient preferences. Prospective studies will be important to further assess differences in patient outcomes.

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.

Objectives To evaluate whether extracellular volume (ECV) fraction derived from contrast‐enhanced computed tomography (CT) is associated with recurrence risk in patients with treatment‐naïve high‐risk non‐muscle‐invasive bladder cancer (HR‐NMIBC) receiving intravesical gemcitabine/docetaxel (Gem/Doce) therapy. Patients and Methods This retrospective cohort study, conducted at a tertiary referral centre, included 103 patients with HR‐NMIBC treated with intravesical Gem/Doce between 2012 and 2024. All patients underwent pre‐resection contrast‐enhanced CT with an equilibrium phase (~3 min post‐injection). Tumour ECV fraction (%) was calculated using the formula: ECV = (ΔHUtumour/ΔHUaorta) × (1 − haematocrit) × 100, where Δ Hounsfield units (HU) represents the change in attenuation between non‐contrast and equilibrium phases. Regions of interest were manually placed in the tumour and abdominal aorta, and haematocrit values obtained within ±10 days were used. Associations between clinical variables, ECV, and recurrence were evaluated using Cox proportional hazards models, with discrimination assessed by Uno's C‐statistic. Results The median (interquartile range) follow‐up was 17 (10–25) months. High‐grade recurrence‐free survival (HG‐RFS) was 76% at 12 months and 69% at 24 months. CT‐derived ECV was the only variable significantly associated with HG‐RFS (hazard ratio 1.05, 95% confidence interval 1.03–1.08), demonstrating strong discrimination (C‐statistic, 0.81; P < 0.01). A 15% threshold offered the best sensitivity–specificity trade‐off (~70% each) for predicting HG‐RFS at 12 and 24 months. Patients with ECV ≤15% had markedly better HG‐RFS than those with ECV >15% at 24 months (88% vs 41%). Conclusions The CT‐derived ECV is a practical, first‐of‐its‐kind imaging biomarker associated with recurrence risk and useful for risk stratification in patients with HR‐NMIBC treated with intravesical Gem/Doce, a regimen increasingly used in the setting of global Bacillus Calmette‐Guérin shortages and intolerance. ECV can be rapidly quantified from routine contrast‐enhanced CT using standard picture archiving and communication system (PACS) tools, without additional imaging or proprietary software, making it a feasible metric for integration into risk‐adapted management pending large‐scale validation with extended follow‐up.

9525 Background: Melanocortin-1 receptor (MC1R) is a novel target for radiopharmaceutical therapy and is highly expressed on melanoma tumor cells. VMT01 is an MC1R-targeted peptide. 203 Pb is used for patient selection via SPECT imaging. Peptide radiolabeling with 212 Pb delivers alpha-particle therapy. Here, we present data on the treatment of adult patients with MC1R-positive metastatic melanoma receiving [ 212 Pb]VMT01 either as a monotherapy or in combination with the programmed death-1 (PD-1) checkpoint inhibitor, nivolumab. Methods: This is an ongoing phase I/IIa, first-in-human, prospective, multicenter, open-label, radioactive dose-finding and dose-expansion trial. The objectives are to investigate safety, pharmacokinetics, dosimetry, and efficacy. Participants receive up to 3 treatment cycles with either [ 212 Pb]VMT01 3 mCi, 5 mCi, or 1.5 mCi monotherapy, or combination therapy with [ 212 Pb]VMT01 (1.5 mCi) + nivolumab (480 mg, Q4W) or [ 212 Pb]VMT01 (3 mCi) + nivolumab. Participants are evaluated for any DLTs for the first 6 weeks after cycle 1. Efficacy is assessed by RECIST v1.1 criteria by the investigator. Results: As of 24 December 2025, 26 participants (53.8% male; median age: 68 years [range: 27-81]) with MC1R-positive metastatic melanoma were enrolled. The median prior systemic therapies was 4. All 26 enrolled participants received ≥1 dose of [²¹²Pb]VMT01. No DLTs were reported. All SAEs (including one grade 5 SAE) were attributed to disease progression. Most TEAEs were grade 1 (19.2%) and grade 2 (34.6%). Grade 3 TEAEs occurred in 8 participants (30.8%), 5 on monotherapy and 3 on combination therapy (3 mCi + nivolumab). Of the 22 evaluable participants, 1 PR, 9 SD, and 12 PD were reported. Four participants had progression-free survival of ≥6 months. Conclusions: [ 212 Pb]VMT01 as a monotherapy and in combination with nivolumab was generally safe and well-tolerated in 26 enrolled participants, with antitumor activity observed at the 3 mCi dose level. These data may be supplemented with a more complete follow-up at the time of the meeting. Clinical trial information: NCT05655312 .