Citations

Abstract Background and Objective Management of von Hippel–Lindau (VHL) disease is challenging due to multisystem involvement and limited systemic treatment options. Belzutifan has shown promising efficacy in clinical trials; however, real-world data remain limited. We aimed to evaluate its effectiveness and safety in a real-world cohort. Methods We conducted a retrospective study of 59 patients with VHL disease treated with belzutifan between August 2021 and January 2026. Objective response rates (ORR) for renal cell carcinoma (RCC), central nervous system hemangioblastomas (CNS HB), and pancreatic neuroendocrine tumors (pNET) were assessed by an independent radiologist. Retinal hemangioblastoma outcomes were evaluated through ophthalmology records by chart review. Results Median follow-up was 29 months. ORR was 27.6%, 39.6%, and 85.7% for RCC, CNS HB, and pNET, respectively. Among 13 patients with retinal hemangioblastomas (20 eyes), 17 eyes (85%) showed improvement. At data cutoff, 47 patients (79.6%) remained on treatment, while 12 (20.3%) discontinued (7 due to adverse events, 3 to disease progression, and 2 to other reasons). The most common adverse event was anemia (86.4%). Grade ≥3 events occurred in 10 patients (16.9%). The procedure rate per patient-year decreased from 0.35 in the 3 years prior to treatment to 0.08 during follow-up (Incidence Rate Ratio, 0.23; 95% CI, 0.12–0.47; P < 0.001) Conclusions Belzutifan demonstrated efficacy across VHL-associated lesions, with favorable safety profile. Most adverse events were grade 1–2. A reduction in procedure rate was observed after treatment initiation.

21 Background: Large language models (LLMs) are becoming an increasing source of medical information for both patients and providers. Clinical decision making is occasionally complex and may use factors outside of traditional guidelines. We conducted a comparative performance evaluation of frontier models on standardized genitourinary (GU) oncology knowledge assessments derived from the American Society of Clinical Oncology Self-Evaluation Program 2025 (ASCO SEP 2025) in addition to challenging questions developed by GU oncology experts. Methods: Three frontier LLMs were selected: ChatGPT-5.2 (OpenAI, San Francisco, CA, USA), Claude Opus 4.6 (Anthropic, San Francisco, CA, USA), and Gemini 3 Pro (Google DeepMind, Mountain View, CA, USA). Model selection was based on publicly reported performance on “Humanity’s Last Exam,” a benchmark of advanced scientific reasoning (Scale AI leaderboard Jan-Feb 2026). The OpenEvidence (OpenEvidence Inc., MA, USA) search engine was also selected for evaluation. All models were asked 145 ASCO SEP 2025 GU oncology questions and 12 real world challenging scenarios using an uniform prompt. Subject matter experts peer reviewed LLM generated responses to challenging questions and credit was given only for correct rationale and option selection. Results: All models demonstrated high and comparable accuracy on Standardized knowledge assessment, with Gemini 3 Pro leading numerically at 97.24% (95% CI, 93.1% – 99.0%), OpenEvidence followed with an accuracy of 94.48% (95% CI, 89.5% – 97.3%), while Chat GPT -5.2 and Claude OPUS 4.6 scored 92.41% (95%, CI 86.9% – 95.7%) and 79.31% (95% CI, 71.9% – 85.1%) respectively. On challenging real world scenarios, ChatGPT-5.2 demonstrated the highest numerical accuracy at 100% (95% CI, 75.8% – 100%), Gemini 3 Pro and Open Evidence scored 75.0% (95% CI, 46.8%–91.1%) each, followed by Claude Opus 4.6 at 66.7% (39.1–86.3). Conclusions: All current frontier AI models appear to provide accurate medical information and rationale on a large majority of guideline based medical knowledge assessments for GU oncology. Frontier AI models also appear to have emerging competence in highly challenging real-world scenarios. AI based tools may become a valuable and reliable tool for patients and providers. Comparative LLM performance. Model ASCO SEP 2025 % (95% CI) Real World Scenarios % (95% CI) Gemini 3 Pro 97.24% (93.1–99.0) 75.0% (46.8–91.1) OpenEvidence 94.48% (89.5–97.3) 75.0% (46.8–91.1) ChatGPT-5.2 92.41% (86.9–95.7) 100% (75.8–100) Claude Opus 4.6 79.31% (71.9–85.1) 66.67% (39.1–86.3)

e17027 Background: Guidelines recommend active surveillance for low-risk prostate cancer and definitive therapy for high-risk disease. We evaluated national patterns of risk-misaligned care and the survival consequences of undertreatment. Methods: National Cancer Database prostate cancer cases diagnosed from 2010–2022 were analyzed. Low-risk disease was defined as clinical T1–T2, Grade Group 1, and PSA < 10; overtreatment was definitive treatment vs active surveillance or no treatment. High-risk disease was defined as Grade Group ≥4, PSA ≥20, or clinical T3–T4; undertreatment was no definitive local therapy or incomplete definitive therapy. Multivariable logistic regression evaluated factors associated with misalignment. Overall survival (OS) among high-risk patients was assessed using multivariable Cox regression. Results: Among low-risk patients (N = 124,562), overtreatment occurred in 40% of cases. Overtreatment was more common among young men (adjusted odds ratio [aOR] 0.982; p < 0.001) and less common at academic centers (aOR 0.414; p = 0.015). Compared with White men, odds of overtreatment were lower among Black men (aOR 0.946; p = 0.002) and Asian men (aOR 0.827; p < 0.001), with additional variation by education and region (all p < 0.001). Among high-risk patients (N = 318,532), undertreatment affected 27.3% of patients and was more common among older men (aOR 1.061; p < 0.001). Compared with White men, undertreatment was higher among Black men (aOR 1.479; p < 0.001) and lower among Asian patients (aOR 0.863; p < 0.001) (overall race p < 0.001). Compared with private insurance, undertreatment was higher in Medicaid (aOR 2.038; p < 0.001) and uninsured patients (aOR 2.649; p < 0.001), and slightly lower with Medicare (aOR 0.931; p < 0.001) (overall insurance p < 0.001). Multiple comorbidities were associated with higher undertreatment (≥2 vs 0: aOR 1.252; p < 0.001). Facility type was not independently associated (p = 0.490), while region remained significant (overall p < 0.001). In the survival cohort (high risk) (N = 338,919), undertreatment was associated with substantially worse OS (HR 2.745, 95% CI 2.706–2.784; p < 0.001), adjusted for age (HR 1.056; p < 0.001), race (p = 0.001), insurance (p < 0.001), comorbidity (p < 0.001), income (overall p < 0.001), education (overall p < 0.001), and facility region (overall p < 0.001). Conclusions: Low-risk overtreatment remains common nationwide and varies across patient and health-system factors. In high-risk disease, undertreatment affects over one-quarter of patients and disproportionately impacts Black men and those with Medicaid or no insurance. Undertreatment confers a nearly threefold mortality hazard (adjusted HR 2.75; p < 0.001), highlighting a major national quality gap and the urgent need for system-level interventions to ensure equitable, guideline-concordant delivery of definitive therapy.

e13611 Background: Decentralized cancer care models may reduce treatment burden for patients with advanced prostate cancer (CaP), particularly those facing mobility, transportation, of scheduling challenges. However, prospective patient-reported experience and quality-of-life data comparing home- versus clinic-based oncology care remain limited. Mayo Clinic Cancer CARE Beyond Walls (CCBW) is a patient-centered program designed to deliver selected standard-of-care cancer therapies in the home with virtual clinical oversight. This observational study evaluated patient-reported experience, feasibility, safety, and quality of life among men with advanced or metastatic CaP receiving care at home. Methods: Men with advanced/metastatic CaP receiving active standard-of-care therapy including hormone-based treatments, oral anticancer therapies, anti-bone resorptive agents, or intravenous chemotherapy who were participating in a CCBW randomized trial were enrolled into a companion observational study. After confirmation of treatment tolerance in clinic, patients received home-based care for 24 weeks (Arm A) or in-clinic care for 8 weeks followed by home-based care for 16 weeks (Arm B). Patient-reported outcomes were collected at baseline and Weeks 8, 16, and 24, using CAHPS-based measures and CCBW-specific surveys assessing overall cancer care experience, patient preference for site of care, comfort with home infusions, functional/symptom assessment and quality of life. Descriptive analyses were performed. Results: Eighteen participants were analyzed (Arm A n = 10; Arm B n = 8). Participants were medically stable, and predominantly insured by Medicare. Survey completion was 100% at baseline and 83% at all follow-up time points. At Weeks 16 and 24 when all respondents had received home-based care, 100% and 92% reported being “quite a bit” or “very much” comfortable receiving treatment at home. Communication with at-home and remote nursing teams was rated highly, and most respondents reported transition, scheduling, and equipment use easy or very easy. At Weeks 16 and 24, 45% and 40% of respondents reported improved quality of life from receiving home-based care, with no reports of worsening. No emergency department visits, hospitalizations, or urgent care visits occurred in either arm. Conclusions: In this prospective, observational study, home-based oncology care delivered through CCBW was feasible, safe, and associated with high patient satisfaction among men with advanced CaP receiving diverse systemic therapies. These findings support further evaluation and expansion of decentralized care integrating home-based treatment with virtual clinical oversight.

9558 Background: Ipilimumab 3 mg/kg plus nivolumab 1 mg/kg (Ipi3+Nivo1) is the standard immunotherapy regimen for metastatic melanoma with brain metastases (MBM) but is associated with significant immune-related toxicity, particularly neurologic toxicity. Ipilimumab 1 mg/kg plus nivolumab 3 mg/kg (Ipi1+Nivo3) has demonstrated improved tolerability in extracranial melanoma, though comparative data in MBM are limited. We compared efficacy and toxicity of these dosing strategies in a multisite real-world cohort. Methods: We retrospectively identified patients with MBM treated with ipilimumab plus nivolumab across three Mayo Clinic sites between 2016 and 2024. Patients were classified by induction dosing as Ipi1+Nivo3 or Ipi3+Nivo1. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan–Meier method and compared using log-rank tests. Best overall response (BOR) and toxicity outcomes were summarized descriptively. Results: Among 147 patients (Ipi1+Nivo3 n=32; Ipi3+Nivo1 n=115), 144 were evaluable for survival. Median age was higher in the Ipi1+Nivo3 group (69.5 vs 66.0 years); males predominated in both groups (71.9% vs 61.7%), and the cohort was predominantly White (>96%). Most patients had ECOG 0–1 in both groups (84.4% in Ipi1+ Nivo3 and 90.4% in Ipi3+Nivo1). BRAF mutation status was balanced between regimens, with approximately half of patients harboring BRAF-mutant disease (51.6% vs 53.2%). Median OS was 18.5 months (95% CI, 5.7–54.7) with Ipi1+Nivo3 versus 10.6 months (95% CI, 6.5–19.1) with Ipi3+Nivo1 (log-rank p=0.25). Two-year OS was 45.9% and 35.0%, and five-year OS was 24.5% and 19.2%, respectively. Median PFS was 7.3 months (95% CI, 1.8–10.9) versus 2.8 months (95% CI, 2.1–4.4) (log-rank p=0.16). BOR was available for 138 patients; objective response rates were 35.5% and 31.8%, respectively. 3–5 adverse events occurred in 24.1% of Ipi1+Nivo3 versus 30.5% of Ipi3+Nivo1 patients. Hospitalizations were less frequent (16.7% vs 36.1%), and neurologic adverse events occurred only with Ipi3+Nivo1 (11.9% vs 0%). Conclusions: In this multisite real-world MBM cohort, Ipi1+Nivo3 demonstrated comparable efficacy, numerically longer survival, and a more favorable toxicity profile compared with standard Ipi3+Nivo1. Notably, no neurologic toxicity was observed with the Ipi1+Nivo3 regimen. These findings support further prospective evaluation of lower dose ipilimumab strategies. Response and survival outcomes. Outcome Ipi1 + Nivo3 Ipi3 + Nivo1 Complete response (CR) 2 / 31 (6.5%) 8 / 107 (7.5%) Partial response (PR) 9 / 31 (29.0%) 26 / 107 (24.3%) Objective response rate (ORR = CR+PR) 11 / 31 (35.5%) 34 / 107 (31.8%) Disease control rate (DCR = CR+PR+SD) 18 / 31 (58.1%) 51 / 107 (47.7%) Median PFS, months (95% CI) 7.3 (1.8–10.9) 2.8 (2.1–4.4) 2-year PFS 27.6% 22.3% Median OS, months (95% CI) 18.5 (5.7–54.7) 10.6 (6.5–19.1) 2-year OS 45.9% 35.0% 5-year OS 24.5% 19.2%

Abstract Medical advancements with immunotherapy have cured some patients with previously incurable metastatic renal cancer. We present the case of a 74-year-old male metastatic renal cancer patient who received only one dose of the combination of ipilimumab with nivolumab. In response to his treatment, he developed autoimmune hepatitis, myasthenia, myositis, and myocarditis. Although these serious side effects are considered to rarely occur, they can quickly become life-threatening and even fatal. These immune-related adverse events (irAEs) may further develop into secondary life-threatening symptoms such as respiratory failure due to advanced myasthenia; cardiotoxicity of myocarditis with possible cardiogenic shock, cardiac arrest, and severe heart failure; and liver failure consequently from autoimmune hepatitis. Furthermore, the ability for physicians to detect immunotherapy toxicity early is extremely important in intervening in a timely manner to avoid lethal conditions for the patient. With patients receiving immunotherapy, communication, collaboration, and multidisciplinary care are essential. Any subtle or sudden changes in their health status or symptoms should prompt further investigation. It is our purpose to highlight this patient to raise awareness of toxicity to significantly reduce the fatality rates and increase the therapy’s success rate in the years to come. Citation Format: Orianna Guarisma-Lugo, Roderick Brice, Samuel Ramirez, Winston W. Tan. The unique presentation of four immunotherapy toxicities in a single patient [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3803.

Abstract Background: Melanoma brain metastases (MBM) represent a biologically distinct and clinically aggressive subset of melanoma. Comprehensive molecular characterization focused on intracranial disease remains limited. We aimed to define the genomic landscape of MBM and compare these findings with public melanoma datasets. Methods: We retrospectively identified 166 patients with histologically confirmed MBM across Mayo Clinic tri-sites (2011-2025). Molecular testing was performed in 123 patients (74.1%). Comprehensive next-generation sequencing (NGS; ≥300-gene platforms including Tempus, FoundationOne, Caris, NeoGenomics, and MayoComplete Solid Tumor Panel) was available in 41 patients (24.7%). Intermediate-depth profiling using the MayoComplete Melanoma Panel (17 genes) was performed in 21 patients (12.7%), and a targeted 5-gene melanoma driver panel (BRAF, NRAS, KIT, GNAQ, GNA11) in 52 patients (31.3%). cfDNA-based NGS was available in 12 patients (7.2%). Genomic alterations were summarized and benchmarked against TCGA-SKCM and MSK-IMPACT datasets via cBioPortal. We considered assay heterogeneity, as Mayo panels varied in sequencing depth and CNV coverage, and hybrid-capture platforms often under-detect TERT promoter hotspots. Results: Patients had a median age of 67 years, and 63% were male. BRAF mutations occurred in 48.8% (BRAF V600E/K 41.6%; non-V600 7.2%). Additional MAPK alterations included NRAS (17.5%), KIT (5.4%), GNAQ (1.2%), and GNA11 (0.6%). In the comprehensive NGS subset, tumor-suppressor alterations included CDKN2A (17.5%), PTEN (7.8%), NF1 (9.0%), TP53 (8.4%), and TERT promoter mutations (22.9%). Median TMB was 11.55 mut/Mb (IQR 5.0-25.5). Co-alterations included BRAF+CDKN2A (7.2%), BRAF+PTEN (4.2%), NRAS+CDKN2A (4.2%), NRAS+PTEN (1.2%), and CDKN2A+PTEN (3.6%); overall, 18.1% harbored MAPK driver + tumor-suppressor co-alterations. Compared with TCGA and MSK cohorts, MBM showed similar MAPK driver frequencies but fewer MAPK + tumor-suppressor co-alterations and lower CDKN2A, PTEN, and TP53 disruption, alongside a more prevalent of TERT promoter mutations (22.9% vs 7% and 2.1%), which may partly reflect coverage differences. Conclusion: MBM exhibit a distinct genomic profile characterized by reduced tumor-suppressor loss, fewer MAPK-tumor-suppressor co-alterations, and higher prevalence of TERT promoter mutations. While assay heterogeneity limits direct cross-cohort comparisons, these patterns suggest potentially distinct biological features of intracranial melanoma and underscore the need for harmonized, MBM-specific molecular studies to guide therapeutic development. Citation Format: Dina Elantably, Joseph B. Parker, Jakob Hamilton, Ahmed Abdelhakeem, Oluwatayo Adeoye, Saivaishnavi Kamatham, Winston Tan, Arkadiusz Z. Dudek, Anastasios Dimou, Matthew S. Block, Robert McWilliams, Svetomir Markovic, Mahesh Seetharam, Roxana Dronca, Ruqin Chen. Genomic landscape of melanoma brain metastases: Real-world analysis and comparison with public melanoma cohorts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2107.

465 Background: Molecular testing is crucial in advancing precision medicine, enabling oncologists to tailor targeted treatment strategies for cancer patients (pts). The National Comprehensive Cancer Network (NCCN) and ASCO guidelines recommend comprehensive biomarker testing for pts with mPC. However, compliance can vary considerably among institutions. This study aimed to assess current practices of molecular testing in diverse healthcare settings across the state of Florida and identify opportunities for improvement to optimize outcomes for pts diagnosed with mPC. Methods: We conducted a detailed 12-question survey, distributed both electronically and in-person to evaluate the molecular testing practices of healthcare providers throughout the state. The survey assessed multiple parameters including adherence to testing, reviewing test results to guide treatment decisions, and the availability of different supportive resources in biomarker testing. This initiative was executed in partnership with the Florida Society of Clinical Oncology and industry partners. Results: A total of 40 responses were collected from 11 institutions in Florida, including 5 academic centers and 6 community-based hospitals. Notably, 22.5% of respondents reported that their institutions either do not fully comply with NCCN guidelines or lack protocols to identify eligible pts and 67.5% stated they are responsible for their own biomarker education and updates. Only 56.4% consistently review molecular testing results during disease progression to guide treatment decisions. Nearly all institutions lack clinical decision support tools in the electronic medical records (EMR) to support testing, and 82.5% receive biomarker results outside the EMR. Additionally, 38.5% lack a standard process for obtaining prior authorization for testing. Furthermore, 38.5% lack a multidisciplinary review process for genetic test results, and 76.3% reported that their biomarker testing process does not involve geneticists or genetic counselors. Conclusions: Our study identified critical gaps in adherence to biomarker testing guidelines with many practices lacking decision support tools across healthcare institutions in Florida. Potential areas for improvement include better standardization of result integration into EMR, targeted educational initiatives, and stronger multidisciplinary collaborations. The implementation of these measures aims to improve the quality of care and outcomes for pts with mPC.

LBA1551 Background: Traditional cancer therapy is primarily delivered in clinical settings, imposing logistical, emotional, and financial burdens, particularly on rural and underserved patients. While international studies have demonstrated the safety of home-based chemotherapy, no randomized U.S. trials have evaluated this approach. Mayo Clinic’s CCBW program aims to expand access to high-quality cancer care by providing in-home cancer treatment, lab testing, telemedicine, remote patient monitoring, command center and paramedic support. This pragmatic randomized controlled trial evaluates feasibility and impact of home-based versus in-clinic cancer directed therapy on patient preference, acceptability, safety, and patient-reported outcomes. Methods: Adult patients (ECOG 0-2) receiving chemotherapy or hormonal therapy at Mayo Clinic Florida were randomized 1:1 after confirmation of treatment tolerance in clinic to receive (1) home-based care for 24 weeks or (2) in-clinic care for 8 weeks followed by home-based care for 16 weeks. Target accrual is 200 patients. A planned interim analysis after 50 enrollments assessed accrual, data completeness, technical challenges, safety, and study outcomes. The primary endpoint is patient ratings of their overall cancer care experience (0–10 scale, CAHPS Cancer Care Survey) at 8 weeks. 200 patients provide 80% power to detect a 0.45 standard deviation difference in mean ratings between arms with a 2-sided 2-sample t-test (α=0.05) and 20% missing data rate. Secondary endpoints are patient preference, comfort with home infusions, treatment worthwhileness, functional/symptom assessments (EORTC QLQ-F17, PRO-CTCAE, GP5), grade ≥3 AEs, hospitalizations, and overall survival. Cost is a tertiary endpoint. The trial is IRB-approved (#23001719) and registered (NCT05969860). Results: Enrollment began 8/23/23. As of 2/21/25, 52 patients (26 per arm) were enrolled and 36 started protocol treatment. Common cancers were breast (38%), colorectal (21%), prostate (19%), and multiple myeloma (14%). 64% (28/44) of patients were female; 84% identified as White, 14% as Black, and 2% as multiple races. Median distance to clinic was 20 miles (range 2-66). After 8 weeks, patients in both arms rated their overall cancer care experience highly (mean [SD]=9.69 [0.85] versus 9.54 [0.66] for home-based vs. in-clinic care, n=26). After 24 weeks, 73% preferred home-based care, 18% had no preference, and 9% preferred in-clinic care; 100% felt comfortable with home infusions. No grade ≥3 AEs related to location of care have occurred. Conclusions: Early findings support the feasibility, safety, and high patient acceptability of home-based cancer therapy. No safety concerns related to care location were observed and most patients preferred home-based treatment. Ongoing accrual and analysis will assess clinical outcomes and cost implications. Clinical trial information: NCT05969860 .

TPS1657 Background: Cancer treatments are traditionally administered in clinical settings, which can isolate patients from their familiar environments and exacerbate physical, psychosocial, and financial burdens. Travel requirements further amplify these challenges, particularly for underserved populations. Studies indicate that patients prefer receiving care at home, and international models have demonstrated the safety of home-delivered chemotherapy since the 1990s; however, no U.S. clinical trial data exists. In response, Mayo Clinic has developed the Cancer CARE (Connected Access and Remote Expertise) Beyond Walls (CCBW) program, a distributed cancer care delivery model that expands access to quality cancer care by bringing it to the home environment, providing in-home cancer treatment, lab testing, telemedicine, and community paramedic support. This trial evaluates the safety, acceptability, and impact of home-based subcutaneous (SC) nivolumab (Nivo) administration compared to in-clinic treatment within the CCBW initiative. Methods: This open-label, single-arm trial evaluates the impact of SC Nivo administration location—home versus infusion center—on patient reported cancer care experience, patient-preferred treatment location, acceptability, safety, and patient-reported outcomes. Eligible adult patients (ECOG 0-1) receiving IV Nivo for an FDA-approved indication and residing within 75 miles of Mayo Clinic Florida will transition to SC Nivo, receiving two initial in-clinic cycles. If tolerated without injection reactions, four cycles will be administered at home before resuming in-clinic treatment. Exclusion criteria include concurrent investigational/standard treatments or contraindications to immunotherapy. Fifty patients will be enrolled, with an estimated 75% (n=38) providing cancer care ratings after 8 weeks in-clinic and 8 weeks at-home, offering 85% power to detect a mean difference in ratings of 0.50 standard deviations. The primary endpoint is within-patient change in cancer care rating (0–10 scale, CAHPS Cancer Care Survey) comparing 8 weeks of in-clinic vs. at-home care. Secondary endpoints include patient-preferred treatment location, comfort with home injections, safety (grade 3+ adverse events), function (EORTC QLQ-F17), symptoms (PRO-CTCAE), side effect impact (GP5), and healthcare utilization (ER visits, hospitalizations). Cost will be assessed as a tertiary endpoint. The trial has FDA approval (IND #170079), Mayo Clinic IRB approval (#23009663), and ClinicalTrials.gov registration (NCT06265285). Enrollment began in April 2024, with an expected accrual period of 24 months. To date, 10 patients have been enrolled, and final analysis is expected 2.5 years after trial activation. Clinical trial information: NCT06265285 .