Bekaii‐Saab, Tanios

4017 Background: First-line mCCA treatment is chemotherapy and immunotherapy. Based on the phase 2 FIGHT-202 trial, pemigatinib was the first FGFR1-3 inhibitor approved in second line and beyond for mCCA with FGFR2 rearrangement. Results from the phase 3, randomized, global FIGHT-302 trial evaluating pemigatinib as first-line therapy are reported here (NCT03656536). Methods: Patients (pts) aged ≥18 y with previously untreated mCCA with FGFR2 rearrangement were randomized 1:1 to receive oral pemigatinib (13.5 mg once daily q21) or intravenous chemotherapy (1000 mg/m 2 gemcitabine + 25 mg/m 2 cisplatin d1,8 q21 ≤8 cycles) stratified by previous receipt of 1 chemotherapy cycle, geographic region, and tumor burden. Pemigatinib crossover was allowed for control arm pts progressing on chemotherapy. Primary end point was progression-free survival (PFS). Secondary efficacy, safety, and exploratory end points were also analyzed. Results: After prescreening >4000 pts, only 196 had FGFR2 rearrangement and were screened; 167 were randomized to receive pemigatinib (n=83) or chemotherapy (n=84) before closing the study early due to slow accrual. Baseline characteristics and demographics were similar between arms. Median PFS (mPFS) with pemigatinib versus chemotherapy was 8.3 versus 6.8 mo, respectively (hazard ratio [95% CI], 0.58 [0.39-0.87]; nominal P =.0078); secondary efficacy endpoints generally supported primary results (Table). Median OS was similar, although these results are confounded by FGFR inhibitor administration as second-line treatment. In the crossover group (n=42, second-line pemigatinib), mPFS was 8.1 mo. Safety was consistent with previous results (Table). Exploratory analyses of genetic co-alterations associated with treatment response will be presented. Conclusions: FIGHT-302 was the first phase 3 trial of a targeted therapy for untreated mCCA. Pemigatinb demonstrated superior activity and prolonged mPFS compared with first-line chemotherapy. The results confirm the current management paradigm of pemigatinib administration after disease progression on chemotherapy. Clinical trial information: NCT03656536 . Pemigatinib Gemcitabine + cisplatin mPFS (95% CI), mo a 8.3 (6.5-12.2) 6.8 (6.1-8.3) Objective response rate, n/N (%) a 39/83 (47) 13/84 (15.5) Median duration of response (95% CI), mo a 14.2 (8.7-24.7) 6.3 (4.3-not estimable) Median overall survival (95% CI) a,b , mo 24.4 (18.6-35.9) 25.0 (18.7-34.2) Treatment related TEAEs, n/N c (%) 80/83 (96) 70/73 (96) Serious TEAEs, n/N (%) c,d 23/83 (28) 17/73 (23) Grade ≥3 TEAEs, n/N (%) c 65/83 (78) 49/73 (67) TEAEs leading to treatment discontinuation, n/N (%) c 5/83 (6) 8/73 (11) Fatal TEAE, n/N (%) c,d 3/83 (4) 0 a All randomized pts. b Interpretation limited by second-line treatment with FGFR inhibitor in gemcitabine + cisplatin arm. c Pts who received ≥1 study dose. d None deemed treatment related.

3592 Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent dose-limiting toxicity from oxaliplatin that impairs quality of life in gastrointestinal (GI) cancer patients (pts). While strategies to limit exposure exist, their impact on survival remains debated. We evaluated whether reduced oxaliplatin exposure (ROE) maintains survival while mitigating toxicity. Methods: We conducted a systematic review and meta-analysis (PubMed, Embase, Scopus, Web of Science, EBM Reviews) of studies comparing ROE vs standard-duration oxaliplatin-based chemotherapy in GI cancers. ROE was defined as planned limitation of oxaliplatin exposure, including shortened duration (3-4 months), maintenance-based de-escalation, or stop-and-go strategies. Primary endpoints were disease-free survival (DFS) in curative settings, progression-free survival (PFS) in palliative settings, and overall survival (OS). Secondary endpoints included grade ≥3 CIPN and grade ≥3 adverse events (AEs). Random-effects models used Hartung-Knapp-Sidik-Jonkman correction. Heterogeneity was assessed via I² and Cochran’s Q. Results: 24 studies, comprising 15 randomized controlled trials (RCTs) and 9 retrospective cohorts, were included (N = 30,404 pts; ROE: 13,348; control: 17,056). Settings included adjuvant colorectal cancer (CRC; n = 14), metastatic CRC (mCRC; n = 5), gastric cancer (GC) (adjuvant n = 1, metastatic n = 3), and metastatic pancreatic cancer (PDAC) (n = 1). ROE strategies included shortened duration (n = 14), maintenance (n = 8), and stop-and-go (n = 2). In adjuvant CRC, ROE did not compromise DFS (HR 1.07; 95% CI, 0.98-1.16; p = 0.12; I² = 21.7%), including in high-risk subgroups (HR 1.14; 95% CI, 0.93-1.40; p = 0.14; I² = 38.9%); OS was also not different between groups (HR 1.00; 95% CI, 0.94-1.07; p = 0.89; I² = 0%), including high-risk pts (HR 1.01; 95% CI, 0.93-1.10; p = 0.68; I² = 0%). In mCRC, ROE showed no detriment to PFS (HR 1.11; 95% CI, 0.99-1.25; p = 0.07; I² = 0%) or OS (HR 1.06; 95% CI, 0.92-1.23; p = 0.33; I² = 0%). Similarly, in metastatic gastric cancer, PFS (HR 0.82; 95% CI, 0.34-1.99; p = 0.44; I² = 77.3%) and OS (HR 0.90; 95% CI, 0.67-1.21; p = 0.26; I² = 0%) were comparable. Findings remained concordant after restricting the analysis to only RCTs. Pooled analysis was not feasible for PDAC and adjuvant GC studies, but individual study findings were consistent with the above. ROE significantly reduced the risk of grade ≥3 CIPN (OR 0.32; 95% CI, 0.20-0.53; p < 0.001; I² = 80.6%) and overall grade ≥3 AEs (OR 0.65; 95% CI, 0.50-0.86; p = 0.01; I² = 59.9%). Conclusions: Across GI malignancies, ROE was not associated with inferior DFS, PFS, or OS and was associated with lower rates of severe neurotoxicity and high-grade AEs. These findings support planned limitation of oxaliplatin exposure as a strategy to improve the therapeutic index of oxaliplatin-based chemotherapy across disease settings.

PURPOSE Hepatopancreatobiliary (HPB) cancers—including hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), pancreatic ductal adenocarcinoma (PDAC), and gallbladder cancer—are aggressive malignancies with limited treatment options and poor prognosis. The emergence of personalized liquid biopsy technologies, particularly bespoke circulating tumor DNA (ctDNA), offers new opportunities for improving clinical management. Traditional methods like imaging and tumor markers may miss early recurrence or evolving disease. This study explores the real-world application of ctDNA in HPB cancers, focusing on its use for surveillance, diagnostic clarification, treatment monitoring, and recurrence detection. Methods We retrospectively analyzed the use of a personalized ctDNA assay (Signatera, Natera) in 54 patients with HPB cancers at a single academic cancer center. The cohort included PDAC (22/54), HCC (11/54), and CCA (21/54). ctDNA was assessed longitudinally for surveillance, treatment monitoring, or diagnostic clarification. Concordance with imaging and tumor markers, as well as lead time to recurrence detection, was descriptively analyzed. RESULTS ctDNA was evaluable in 37/54 patients (84.6%), with ctDNA positivity in 22/37 (59.5%). Success rates by tumor type were 16/22 (72.7%) in PDAC, 10/11 (90.9%) in HCC, and 11/21 (52.4%) in CCA. ctDNA concordance with imaging was observed in 69/85 assessments (72.6%) and with tumor markers (carbohydrate antigen 19-9 or alpha fetoprotein) in 39/95 (41%). Clinical applications included disease surveillance (21/54, 38.9%), treatment monitoring (24/54, 44.4%), and diagnostic clarification (16/54, 29.6%). In patients with recurrence, ctDNA detected disease before imaging in several cases, with a median lead time of 28 days (range, 1 month to 7 months). CONCLUSION Personalized ctDNA testing demonstrated meaningful utility across HPB cancers, enabling early recurrence detection and guiding clinical decision making as a complementary tool in multidisciplinary care.

PURPOSE Homologous recombination deficiency (HRD) is a key determinant of sensitivity to DNA-damaging agents; however, its genomic characterization in colorectal cancer (CRC) remains limited. This study investigated whether low RNA expression of homologous recombination (HR) genes identifies patients with metastatic CRC who derive survival benefit from oxaliplatin- or irinotecan-based therapy. METHODS A total of 22,957 metastatic CRC samples were subjected to DNA and RNA sequencing (Caris Life Sciences, Dallas, TX). Patients with microsatellite instability–high or pathogenic HR gene mutations were excluded to define a HR-proficient cohort. Overall survival (OS) was compared between patients with low (bottom 25%) versus high (top 25%) RNA expression of HR genes after oxaliplatin or irinotecan exposure. Validation was performed in the PARADIGM phase III trial cohort (n = 262) of first-line modified fluorouracil, leucovorin, and oxaliplatin-treated patients with available RNAseq data. RESULTS In the discovery cohort, low expression of core HR genes correlated with significantly longer OS after oxaliplatin or irinotecan exposure, specifically RAD51 (43.0 v 36.3 months; P < .005) and BLM (42.9 v 34.2 months; P < .005). Similar associations were observed for RAD51 (28.1 v 22.9 months; P = .02) and BLM (29.1 v 23.2 months; P < .005) in irinotecan-treated patients. In the PARADIGM validation cohort, low BLM expression was associated with improved OS (41.5 v 22.4 months; HR = 0.52; P = .002), whereas RAD51 showed a favorable but nonsignificant trend. These findings remained significant after adjustment for treatment arm, tumor sidedness, and metastatic burden. CONCLUSION Low BLM RNA expression is associated with improved survival after treatment with DNA-damaging agents, whereas low RAD51 expression shows a favorable but nonsignificant trend. These findings are exploratory and suggest that RNA-based HR gene expression may warrant further investigation as a potential prognostic biomarker in metastatic CRC.

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.

PURPOSE For patients with advanced biliary tract cancer (BTC), cancer-related time spent in health care systems, time toxicity, represents a critical but understudied burden affecting quality of life. This study aimed to quantify time toxicity in patients receiving first-line systemic therapy and evaluate whether the addition of durvalumab to gemcitabine plus cisplatin (GC) increases health care contact time. METHODS This international, multicenter, retrospective cohort study included patients with advanced BTC seen between January 2019 and April 2024 at Mayo Clinic Enterprise (US), and between January 2021 and April 2024 at Kyorin University Hospital (Japan), and Hospital Israelita Albert Einstein (Brazil). Patients received GC plus durvalumab (GCD) or GC. Time toxicity was recorded from treatment initiation until discontinuation or last follow-up during first-line systemic therapy. Multiple regression analysis identified factors associated with high time toxicity. RESULTS Among 193 patients (102 GCD, 91 GC; median age 65 years; 50% male; 49% Eastern Cooperative Oncology Group performance status [PS] 0), median time on treatment (TOT) was 156 days (95% CI, 122 to 190). The median proportion of total time toxicity was 14.4% (IQR, 10.9-20.6). Planned visits accounted for 11.9%, while unplanned visits were infrequent (1.8%). Time toxicity strongly correlated with TOT ( r = 0.824) and progression-free survival ( r = 0.827). Despite longer treatment in the GCD group than the GC group (212 v 134 days; P = .027), total time toxicity was similar (27 v 18 days; P = .19). Younger age and poor PS were independent factors of higher time toxicity. CONCLUSION Time toxicity represents a meaningful metric that allows for more comprehensive integration of the net benefit in patients with advanced BTC with a limited lifespan.

Background and Aims: Cholangiocarcinoma (CCA) is a rare but aggressive malignancy with poorly understood genetic susceptibility. To date, genome-wide association studies (GWAS) investigating germline variants associated with CCA risk remain limited. We aimed to identify genetic risk loci for CCA and its clinical subtypes through comprehensive GWAS and post-GWAS analyses. Approach and Results: We conducted a GWAS of 2366 CCA cases and 11,750 controls of European ancestry. Genome-wide significant loci ( p <5×10 −8 ) were identified and further examined through fine-mapping, functional annotation, and HLA imputation. Subgroup analyses were conducted by CCA subtypes and primary sclerosing cholangitis (PSC) status. Cross-trait linkage disequilibrium score regression and Mendelian randomization were employed to investigate the shared genetic architecture and potential causal relationships with a diverse range of traits. We identified 1 new genome-wide significant variant, rs535777 (OR=1.44), near HLA-DRB1/DQA1 associated with CCA, and 2 variants associated with extrahepatic CCA: rs116224263 (OR=0.17) in LINC02506 at 4p15.1 and rs6914950 (OR=1.63) near HLA-DRB1/DQB1 . Stratified analyses revealed rs2395184 (OR=3.51) near HLA-DRA/DRB5 associated with PSC-related CCA, and rs142674434 (OR=2.98) in THSD7A at 7p21.3 associated with non-PSC-related CCA. HLA imputation uncovered new amino acid residues associated with disease risk. Cross-trait analyses identified shared genetic signals between CCA and anthropometric, lipidemic, lifestyle, and medical traits. Mendelian randomization supported putative causal associations for 12 traits with CCA or its subtypes. Conclusions: Our large-scale GWAS highlights new genetic variants and HLA-linked mechanisms underlying CCA susceptibility. Integrating multi-step post-GWAS approaches enhances understanding of CCA pathogenesis and may facilitate the development of risk biomarkers for early detection and precision prevention strategies.

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)

830 Background: Immune checkpoint inhibitors (ICIs) are standard therapy for MSI-H GI cancers. Lynch syndrome, caused by germline mutations in mismatch repair (MMR) genes, leads to MSI-H tumors and robust ICI responses, but its effect on irAEs remains poorly defined. Clarifying this risk may inform treatment selection and toxicity monitoring. Methods: We retrospectively reviewed MSI-H or MMR-deficient (dMMR) GI cancer patients (pts) treated with ICIs across Mayo Clinic (AZ, MN, FL) from January 2017 to June 2025. Eligible pts were identified using Mayo Data Explorer. Demographics, treatment, and irAEs (graded per CTCAE v5.0) were collected. Lynch status was determined by germline testing when available. Logistic regression estimated odds ratios (ORs) for any grade and grade ≥3 irAEs, adjusting for age, cancer type, prior chemotherapy, and treatment regimen. Results: A total of 209 pts with dMMR/MSI-H GI cancer were included: 61 with Lynch syndrome and 148 without. Lynch pts were younger (median 58 vs 76 years, p < 0.001) and more likely to have received prior chemotherapy (62% vs 43%, p = 0.009). Colorectal cancer was the predominant cancer type (74%), but Lynch pts had proportionally more non-colorectal GI cancers (15% vs 2.7%, p = 0.007). Overall, 29% of pts experienced an irAE, with rates significantly higher in Lynch vs non-Lynch pts (43% vs 24%, p = 0.005). The most frequent irAEs were gastrointestinal, endocrine, and dermatologic, followed by hepatic and pulmonary events. Grade ≥3 irAEs occurred in 16% overall, with no significant difference between groups (p = 0.124). In adjusted models, Lynch syndrome was independently associated with a higher risk of any grade irAE (OR 2.14, 95% CI 1.09 - 4.19, p = 0.026), while risk of severe irAEs was not increased (OR 1.55, 95% CI 0.64 - 3.59, p = 0.316). Lynch syndrome pts were more likely to have combination therapy (17% vs 6.8%, p = 0.029). However, there were no differences observed in any grade irAE between monotherapy and combination immunotherapy (OR 1.36, 95% CI 0.49 - 3.54, p = 0.535). Conclusions: Lynch syndrome is associated with a higher prevalence of any-grade irAEs among dMMR/MSI-H GI cancer pts treated with ICIs, though severe events were not increased. Incorporating Lynch status into immunotherapy planning may improve risk stratification and guide regimen selection.

817 Background: Universal germline sequencing is increasingly utilized in practice, but existing evidence and guidelines are based on studies in predominantly white populations. This study aims to compare the prevalence of genetic alterations in white vs underrepresented minority (URM) populations and assess incremental findings discovered with universal testing beyond current guidelines. Methods: This prospective, multicenter study analyzed genetic alterations in white and URM cohorts with primary GI malignancies receiving care at Mayo Clinic cancer centers between April 2018 and April 2025. Patients underwent germline sequencing using a next-generation sequencing (NGS) platform targeting over 80 genes. We compared the distribution of results between white and URM populations. Concordance with NCCN testing guidelines and incremental findings were assessed. Results: A total of 1128 patients were studied, of which 758 were white and 370 were URM, (47.6% Hispanic, 22.7% Black, 13.8% Asian, 10.5% American Indian, 0.8% Pacific Islander, and 6.8% other). Pathogenic variants (PGV) were more common in the white population (16.1% vs 9.2% P < 0.001). Variants of uncertain significance (VUS) were more common in the URM population (53.2 vs 43.5%, P<0.001). A total of 156 patients were found to have a PGV. PGVs outside primary cancer genes were more common in white patients (57.4% vs. 32.4%; p=0.0241). Incremental findings from universal testing were higher in white patients (66.4% vs 35.3%; p=0.0011). Conclusions: This study reveals a significant difference in the prevalence of PGV and VUS between white and URM patients with primary GI malignancies. The higher rate of PGVs in white patients and VUS in URM patients highlights potential inequities in both detection and interpretation of genetic results. These findings emphasize the need for broader representation in genetic databases to ensure equitable access to precision oncology. Screening guidelines met by patients with PGV. White (N=122) URM (N=34) Total (N=156) p value Did they meet NCCN testing guidelines for their primary cancer? 0.0991 Yes 87 (71.3%) 29 (85.3%) 116 (74.4%) No 35 (28.7%) 5 (14.7%) 40 (25.6%) Was the PGV outside of the primary genes recommended for their primary cancer? 0.0241 Yes 70 (57.4%) 11 (32.4%) 81 (51.9%) No 47 (38.5%) 22 (64.7%) 69 (44.2%) Incremental Finding 0.0011 Yes 81 (66.4%) 12 (35.3%) 93 (59.6%) No 41 (33.6%) 22 (64.7%) 63 (40.4%)