Jamal, Fares

PURPOSE Gastroesophageal carcinoma (GEC) is increasingly managed using biomarker-guided therapies. Although both tissue DNA (tDNA) and circulating tumor DNA (ctDNA) testing are used clinically, the concordance of genomic alterations between primary tumors, metastatic sites, and liquid biopsy remains incompletely understood. METHODS We retrospectively analyzed 345 patients with GEC who underwent ctDNA testing at Mayo Clinic. tDNA next-generation sequencing and immunohistochemistry (IHC) for human epidermal growth factor receptor 2 (HER2)/erb-b2 receptor tyrosine kinase 2 ( ERBB2 ) and mismatch repair (MMR) were collected. Concordance was evaluated between ctDNA and tDNA, ctDNA and IHC, and across all three modalities, using 60-day and 30-day intervals. RESULTS Among 345 patients with ctDNA testing, 186 had tDNA testing, and 310 underwent IHC. ctDNA testing showed a shorter turnaround time than tDNA (median 6 v 13 days). The most frequent alteration in ctDNA, primary tDNA, and metastatic tDNA was TP53. Concordance between ctDNA and primary tDNA was ≥78.8% for key genes; between ctDNA and metastatic tDNA, it was ≥84.8%. IHC-ctDNA concordance was higher in metastatic tumors, with 91.1% for HER2/ ERBB2 and 97.7% for mismatch repair (MMR)/microsatellite instability (MSI) compared with 81.1% and 95.8%, respectively, in primary tumors. Triplet concordance for MSI/MMR was 97.6% in primary tumors and 100% in metastatic tumors, while ERBB2 /HER2 showed 84.4% and 93.9% concordance, respectively. ctDNA temporal heterogeneity analysis revealed 14 patients with fluctuating ERBB2 status and 3 with fluctuating MSI-H status. CONCLUSION ctDNA testing demonstrates high concordance with tDNA and IHC and offers faster turnaround. Given its minimally invasive nature and strong concordance with tissue-based testing, ctDNA is a reliable tool for genomic profiling and longitudinal monitoring in GEC.

Background: Perianal fistulizing Crohn’s disease (CD) is associated with significant morbidity and remains difficult to treat. Although advanced medical therapies are widely used, much of the available evidence derives from heterogeneous fistula populations or luminal CD trials, with limited perianal-specific synthesis and inconsistent outcome definitions. We conducted a systematic review focusing exclusively on perianal-specific clinical, radiologic, and composite outcomes in adults with perianal fistula (PAF) CD. Methods: We performed a systematic review in accordance with PRISMA 2020. Electronic databases were searched from inception through November 2025. We included randomized controlled trials and cohort studies enrolling adults with CD reporting outcomes specific to PAF. Interventions included biologics and small-molecule therapies, compared with placebo or other therapies. Due to substantial heterogeneity in outcome definitions and study designs, a meta-analysis was not performed. Risk of bias was assessed using Risk of Bias 2 (RoB 2) for randomized trials and the Newcastle–Ottawa Scale for observational studies. Results: Seven studies including >1200 participants with PAF-CD met inclusion criteria. Follow-up ranged from 24 weeks to 5 years. Across studies, outcome definitions and assessment modalities varied. Upadacitinib demonstrated significantly higher clinical fistula closure compared with placebo across multiple dose regimens at 52 weeks. In observational comparisons, ustekinumab and vedolizumab were associated with higher clinical closure rates than anti-TNF therapies. However, infliximab demonstrated higher closure rates than adalimumab as a first-line treatment. The definition for radiologic remission was less consistent across studies and often did not parallel clinical outcomes. Composite clinical–radiologic remission and response were reported in a limited number of studies, with filgotinib showing higher composite outcomes in comparison to placebo in a phase 2 trial. Surgical interventions, relapse outcomes, biomarkers [C-reactive protein (CRP)/fecal calprotectin (FCP)], and patient-reported outcomes were variably reported and not consistently significant across comparisons. Conclusions: Evidence for advanced therapies in PAF CD remains limited by heterogeneity in endpoint definitions, subjectivity in clinical observation, inconsistent radiologic reporting, and reliance on subgroup or observational comparisons. While anti-TNF therapy remains the most established option in guidelines, emerging data suggest significant benefits with ustekinumab, vedolizumab, and JAK inhibitors in selected patients. There is a need for PAF-specific, adequately powered randomized trials using standardized composite clinical and radiologic endpoints.

Pancreatic exocrine insufficiency (PEI) is an under-recognised cause of chronic diarrhoea in patients with neuroendocrine tumours (NETs). If left untreated or undertreated, PEI can lead to complications such as oxalate nephropathy (ON), which may result in loss of kidney function and potentially limit oncologic treatment options, including peptide receptor radionuclide therapy (PRRT). We present a man in his late 60s with a small bowel NET who developed persistent, uncontrolled diarrhoea for several years. The diarrhoea was attributed to multiple factors, including secretory NET (ie, carcinoid syndrome), bile acid diarrhoea and PEI secondary to somatostatin analogue therapy. Due to financial constraints, the patient was unable to consistently take pancreatic enzyme replacement therapy (PERT). Years after the diagnosis of NET, the patient developed a new onset worsening of kidney function. Further work-up, including a kidney biopsy, confirmed ON, which significantly limited subsequent treatment options, including PRRT. Routine screening for PEI and early initiation of PERT should be considered in all NET patients with chronic diarrhoea to prevent ON and preserve future treatment options.

Background: Loeys–Dietz syndrome (LDS) is an autosomal dominant aortopathy characterized by aggressive aneurysm formation and arterial dissections. Pregnancy-related outcomes and timing of LDS diagnosis remain poorly characterized. Methods: Demographics, genetic, obstetric, and vascular data was collected from genetically or clinically confirmed individuals with LDS seen at the three Mayo Clinic sites from 2018 to 2025. Aneurysm progression, new aneurysm formation, and arterial dissections were recorded across all vascular beds. Vascular events were assessed during pregnancy, within 12 months postpartum, and during breastfeeding. Comparative analyses were performed between women with and without a history of pregnancy, and a single-arm descriptive analysis was conducted among patients who experienced vascular complications during the peripartum period. Continuous variables were compared using the Mann–Whitney U test, while categorical variables were analyzed using chi-square or Fisher exact tests. Results: Of 47 women with LDS, 24 had a history of pregnancy, accounting for 54 pregnancies. In the comparative analysis, age at LDS diagnosis differed significantly between women with and without a prior pregnancy: women without prior pregnancy were diagnosed at a younger age (median 23.5 years [IQR 10.8–41.0], n = 23) than those who had been pregnant (median 53.5 years [IQR 43.0–59.3], n = 24). Among pregnant women, the median age at first pregnancy was 28 years (IQR 23–34); only 4 (16.7%) knew their diagnosis before pregnancy. Of 54 pregnancies, 40 (74.1%) resulted in live birth, with 23 (57.5%) vaginal and 17 (42.5%) cesarean deliveries; preterm delivery occurred in 1 (2.5%) pregnancy, and postpartum hemorrhage in 2 (5.0%). No maternal deaths, aortic dissections, or uterine ruptures occurred during gestation or the first postpartum year. In addition, 14 women (58.3%) developed aneurysms, 6 (25.0%) experienced at least one arterial dissection, and 7 (29.2%) required surgical repair, predominantly involving the ascending and abdominal aorta. The prevalence of vascular complications did not differ significantly between groups. Conclusions: In this LDS cohort, pregnancy and the early postpartum period were not accompanied by acute aortic catastrophes, despite frequent diagnostic delay. Although women without prior pregnancy were diagnosed at a younger age, the overall burden of vascular and morphologic complications did not differ significantly by pregnancy history. These findings highlight the importance of long-term cardiovascular follow-up in women with LDS.

837 Background: A recent randomized trial suggested that CR may influence ICI activity in patients with lung cancer. However, the same has not been established in GI cancers, where reports have shown mixed results with variable definitions of 'early' vs 'late' IT. We evaluated multiple approaches to assess the impact of CR on first-line ICI in GI malignancies. Methods: This retrospective study included patients from three Mayo Clinic sites (N=455). Both previously reported IT cutoffs and a new cutoff derived from ROC analysis were evaluated. Patients were categorized by the median of all ITs, the median of the first four ITs, and whether ≥20% of ITs occurred before the identified cutoff. Univariate and multivariate Cox regression (adjusting for age, MSI status, type of cancer, metastasis status, number of cycles, and receipt of chemotherapy with ICI) assessed associations with OS. KM analyses were performed to illustrate survival differences. The primary endpoint was OS. Results: When patients were categorized based on whether ≥20% of infusions occurred before 14:00 (ROC-derived cutoff), a significant association with OS was observed. On univariate analysis, early infusion timing was associated with improved survival (HR 2.30, 95% CI 1.58–3.32, p <0.001). This remained significant after multivariable adjustment (HR 2.11, 95% CI 1.41–3.16, p < 0.001). Median OS was 14.2 months in the early group vs 3.8 months in the late group (log-rank p < 0.001). Using previously defined cutoffs, categorization by the median IT of all infusions or the median of the first four infusions did not demonstrate a significant association with OS in either univariate or multivariate Cox regression analyses. Conclusions: These findings highlight the potential role of infusion timing as a chronotherapy factor in GI cancers. Given the retrospective design and heterogeneous population, prospective studies are warranted to validate this signal and clarify its clinical relevance. Baseline demographics of patients by infusion timing (early vs late). Variables Early N=412 (%) LateN=43(%) Total N=455(%) p-value Age <70 249(60.4) 21(48.8) 270 (59.3) 0.1 >70 163(39.6) 22(51.2) 185 (40.7) Gender F 118(28.6) 16(37.2) 134 (29.5) 0.3 M 294(71.4) 27(62.8) 321 (70.5) Cancer Type Gastroesophageal 109 (26.5) 8 (18.6) 117 (25.7) 0.1 Hepatocellular 159 (38.6) 24 (55.8) 183 (40.2) Biliary 86 (20.9) 4 (9.3) 90 (19.8) MSI-H 58 (14.1) 7 (16.3) 65 (14.3) Metastasis No 150 (36.4) 22 (51.2) 172 (37.8) 0.1 Yes 262 (63.6) 21 (48.8) 283 (62.2) Immunotherapy Cycle Number <6 189 (45.9) 33 (76.7) 222 (48.8) <0.001 >6 223 (54.1) 10 (23.3) 233 (51.2)

629 Background: NENs are a heterogeneous group of tumors with variable clinical behavior. While most NENs occur sporadically, a subset arises in the context of germline cancer predisposition syndromes. The prevalence of GPVs in NENs is increasingly recognized, but the reported frequency and spectrum of genes involved remain inconsistent across studies. Therefore, systematic review and meta-analysis is helpful to clarify the prevalence and clinical significance of PGVs in pts with NENs. Methods: A systematic review with meta-analysis of prospective and retrospective studies reporting germline testing in pts with NENs was conducted according to the PRISMA guidelines. The primary outcome was the prevalence of GPVs. Random-effects models (GLMM) with logit transformation were applied to estimate pooled prevalence with 95% confidence intervals (CIs). Results: Nine studies comprising 1304 patients with NENs were included. The median age was 53.8 (10-88.5) years, 52% were female (n=678/1304), and 56% (n=736/1304) were unselected cohorts (all-comers) and 44% (568/1304) were selected cohorts (testing based on clinical suspicion and high-risk features defined by each study). Across all cohorts, the pooled prevalence of PGVs was 19.6% (95% CI: 10.68–33.15%), with high heterogeneity (I² ≈ 96%). Subgroup analyses demonstrated comparable GPV prevalence between selected (13.2%, 95% CI 6.3–25.8) and unselected cohorts (23.0%, 95% CI 12.0–39.6) (p=0.25). GPV prevalence stratified by pancreatic NENs (17.8%, 95% CI 12.6–24.5) and other NENs (10.6%, 95% CI 6.5–17.0) was also not statistically different (p=0.08). The most altered genes involved DNA repair and cellular signaling pathways, including APC, ATM, BRCA1/2, BAP1, CHEK2, MEN1, MUTYH, VHL, RET, and TSC1/2. Germline variants in mismatch repair (MMR) genes were reported in approximately 2.5% of cases. Conclusions: This study represents the first systematic review and meta-analysis evaluating the prevalence of germline mutations in NENs. Approximately 20% of pts with NENs harbor a germline pathogenic variant, underscoring the importance of genetic counseling and germline testing. The wide variability across studies highlights the need for standardized genetic testing approaches. These findings support routine referral for genetic counseling and panel testing in patients with NENs to guide management and familial risk assessment.

619 Background: Well-differentiated G3 GEP-NETs are rare and heterogeneous diseases, limiting phase III trials and definition of clear standards of care. Building upon our preliminary cohort of 76 patients (pts), we present an updated and expanded retrospective analysis across three Mayo Clinic tertiary centers. Methods: We included pts with histologically confirmed well-differentiated G3 GEP-NETs diagnosed since 2017 (new WHO classification) from the three Mayo Clinic sites (Rochester, Phoenix, Jacksonville). Endpoints were ORR, DCR, PFS, and OS across treatment lines. PFS/OS were estimated by Kaplan-Meier. OS was defined from treatment start. Multivariate Cox regression was used to evaluate the association of clinic-pathologic features (age, sex, tumor functionality, Ki-67, primary tumor site, stage at diagnosis, presence of liver metastasis, number of metastatic sites at diagnosis) with OS (p<0.05). Results: 111 pts (median age 62 y, range 22–83). Primary sites were pancreas (58%), small bowel (19%), unknown (9%), and rectum (5%). Most tumors were G3 at diagnosis (88%); the remainder evolved from prior G1/G2. Ki-67 was 20–55% in 83% of cases. Most were nonfunctional (70%); functional subtypes included carcinoid (13%) and gastrinoma (8%). Median plasma 5-HIAA was 38.5 ng/ml (5–1394). Advanced disease was present in 85%. Common metastatic sites included liver (85%), lymph nodes (32%), bone (26%), peritoneum (10%), and lung (9%). Median number of metastatic sites was 1 (range 0–5). Median number of systemic treatment lines was 2 (range 0–8). The most frequent regimens and outcomes are shown in the Table. Insulin-secreting tumors (HR 2.16, 95% CI 1.33–25.73, p=0.019) and ≥2 metastatic sites (HR 2.13, 95% CI 1.05–4.31, p=0.035) were associated with inferior OS. Conclusions: This represents one of the largest real-world datasets of well-differentiated G3 GEP-NETs and provides a deeper evaluation of treatment strategies and prognostic factors. CAPTEM, SSAs, and PRRT with Lu-177 emerged as the most commonly used therapies, with PRRT showing the most favorable outcomes. Insulin secretion and higher metastatic burden were confirmed as adverse prognostic factors. CAPTEM SSAs PRRT Lu-177 Carboplatin plus etoposide FOLFOX Everolimus Sunitinib N of pts (%) 64 (58) 44 (40) 37 (33) 24 (19) 18 (13) 11 (10) 8 (7) Line of therapy (%) First 36 (56.3) 27 (61.4) 5 (13.5) 13 (59.2) 5 (7.2) 1 (9.0) 1 (12.5) Second 15 (23.4) 13 (29.5) 13 (35.2) 3 (13.6) 5 (35.7) 3 (27.3) 2 (37.5) Third or higher 13 (20.3) 4 (9.1) 19 (51.3) 6 (27.2) 8 (57.1) 7 (63.7) 5 (62.5) DCR (%) 60.9 56.8 75.0 52.2 71.4 45.5 37.5 ORR (%) 34.4 13.6 44.4 30.4 35.7 18.2 12.5 mPFS (95% CI) 8.0 (5.3-10.6) 6.2 (2.8-9.5) 11.2 (9.1-13.3) 7.3 (2.8-11.8) 4.4 (2.4-6.4) 3.9 (2.2-5.6) 3.9 (1.54-6.26) mOS (95% CI) 40.1 (23.0-57.2) 50 (22.6-77.4) 76.1 (16.3-135.8) 33.0 (21.0-45.0) 21.1 (15.0-27.2) NE NE

103 Background: Clinicians spend significant time extracting and synthesizing information to risk-stratify and make adjuvant chemotherapy (AC) recommendations for CRC. By automating parts of this process, LLMs could help reduce documentation burden and variability in decision-making. Methods: We selected 144 stage III, pMMR CRC patients treated at Mayo Clinic (2017–2021). HIPAA-compliant Gemini-2.0-Flash-001 and GPT-4o extracted clinical variables (age, neuropathy grade, pathological stage) from EHRs and generated AC recommendations. Two approaches were compared: (1) a rule-based algorithm with nested if/else statements translating variables into NCCN-based recommendations, and (2) a dynamic LLM agent generating recommendations using a structured prompt informed by NCCN guidelines. Concordance with treating physicians was assessed, with disagreements reviewed by a blinded GI oncologist. Results: The dataset included 144 patients with median age 67 (IQR 66–68), 48.6% female. The LLM pipeline extracted neuropathy grade with 100% accuracy and pathological T/N stages with 99.3% accuracy. Concordance with physician recommendations was 93.1% for the rule-based algorithm and 62.5% for the LLM agent. In discordant cases, blinded adjudication by a GI oncologist favored the algorithm and LLM agent over physicians in most cases (Table 1). Conclusions: This exploratory work shows LLM agents can reliably extract variables and generate evidence-based treatment recommendations for stage III CRC. The high rate of expert preference for LLM recommendations in discordant cases is intriguing but limited by small sample size and possible adjudicator bias. Discordant physician recommendations reflect the complexity of decision-making, including patient preferences, performance status, comorbidities, and subtle findings not fully captured in EHRs. Rather than replacing judgment, we envision LLMs as decision support tools—analogous to an advanced trainee reviewing charts and presenting evidence-based recommendations to the attending physician with ultimate authority. Larger multi-institutional studies with multiple adjudicators are needed to validate these findings and clarify AI’s role in oncology. Patient characteristics, LLM extraction accuracy, and concordance with physician recommendations. Metric Result Total patients 144 Median age (IQR) 67 (66-68) Female (%) 48.6% LLM extraction accuracy – Neuropathy grade 100% LLM extraction accuracy – Pathological T and N stages 99.3% Primary Concordance – Rule-based algorithm vs. physician 93.1% Adjudicator preference of rule-based algorithm over treating physician for discordant cases 100% Concordance – LLM agent vs. physician 62.5% Adjudicator preference of LLM agent over treating physician for discordant cases 82.0%

Abstract Background The increasing reliance on accelerated approvals and surrogate endpoints for Food and Drug Administration (FDA) approvals of gastrointestinal (GI) cancer therapies raises concerns about their clinical benefit and long-term patient outcomes. The shift toward single-arm trials in regulatory decisions further complicates treatment evaluation. Material and Methods This retrospective observational study evaluated all FDA approvals for GI cancer therapies from January 2006 through January 2025. Data were extracted from FDA archives, ClinicalTrials.gov, and PubMed. Approvals were categorized by regulatory pathway (accelerated vs regular), trial design (single-arm vs randomized), and primary endpoint (surrogate vs overall survival [OS]). Clinical benefit was assessed based on OS improvement and the European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS). The primary outcome was the proportion of approvals based on surrogate versus OS endpoints. Secondary outcomes included use of single-arm designs, frequency of accelerated approvals, OS gain, and the proportion meeting ESMO-MCBS substantial benefit (score ≥ 4). Results The FDA granted 60 GI cancer drug approvals from 67 trials. Approvals rose from 15 (25%) in 2006-2014 to 45 (75%) in 2015-2025. Single-arm trials increased to 24%, and surrogate endpoints were used in 41.8% (ORR 20.9%, PFS 19.4%). Median OS improvement was 2.1 months (IQR: 1.6-2.65). Only 24.3% of trials met ESMO-MCBS substantial benefit. Of 15 accelerated approvals, 66.7% remained pending, 13.3% received full approval, and 20% were withdrawn. Conclusion Expedited approvals have improved drug access in GI oncology, but modest benefits highlight the need to balance speed with outcomes that truly matter to patients.

PURPOSE Neoadjuvant immune checkpoint inhibitors (nICIs) have demonstrated high response rates in deficient mismatch repair/microsatellite instability–high (dMMR/MSI-H) gastroesophageal adenocarcinoma (GEA). The NEONIPIGA and INFINITY trials demonstrated high rates of pathologic complete response (pCR) in this patient population. Furthermore, the INFINITY trial explored the feasibility of managing these patients nonoperatively, demonstrating promising results. This study aimed to evaluate clinical outcomes of nICIs in resectable dMMR/MSI-H GEA, with a focus on the feasibility of nonoperative management (NOM). MATERIALS AND METHODS This retrospective cohort study included patients with resectable dMMR/MSI-H GEA and treated with nICIs ± surgery at the Mayo Clinic. Patients were identified from institutional records, and clinical data were retrospectively reviewed. Primary outcomes were clinical complete response (cCR) and pCR. Secondary outcomes included event-free survival (EFS), radiologic complete response (rCR), and immune-related adverse events (irAEs). RESULTS A total of 26 patients treated between April 1, 2017, and July 30, 2025, were identified. Nine patients (34.6%) underwent surgery, of whom six (66.7%) achieved pCR. Seventeen patients (65.4%) pursued NOM, with 10 (71.4%) of 14 evaluable patients achieving cCR and 14 (82.4%) of 17 evaluable achieving rCR. One patient who initially achieved cCR had a local recurrence on surveillance endoscopy and underwent salvage endoscopic resection. At a median follow-up of 19.3 months, 15 (88.2%) of 17 patients in the NOM cohort were alive and metastasis-free, with EFS rates of 87.3% at 12 and 24 months for all patients. irAEs occurred in nine patients (34.6%), with no grade ≥3 toxicities. CONCLUSION In this retrospective cohort study, nICIs led to high cCR and pCR rates in resectable dMMR/MSI-H GEA, supporting the use of immune checkpoint inhibitors in this setting and the feasibility of NOM in select patients.