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Abstract Background Optimal treatment following first-line immunotherapy for advanced hepatocellular carcinoma (HCC) remains uncertain. This study evaluated futibatinib, a pan-FGFR inhibitor, combined with pembrolizumab in previously treated patients with FGF19-expressing HCC. Methods Eligible patients were ≥18 years old with advanced HCC, prior systemic therapy, Child-Pugh A-B7 liver function, ECOG 0–2, and FGF19 overexpression. Patients received futibatinib 20 mg orally daily plus pembrolizumab 200 mg intravenously every 3 weeks. The primary endpoint was progression-free survival at 6 months (PFS6). Secondary endpoints included overall survival (OS), objective response rate (ORR), quality of life, and safety. Results Between August 2021 and March 2024, 14 patients enrolled and 13 were evaluable. Median age was 72 years (range, 60–87), 53.8% were male, 92.3% had Child-Pugh A liver function, and all had received prior immunotherapy. Median progression-free survival was 15 weeks (95% CI, 9.0–NE), with a PFS6 rate of 23.1% (95% CI, 8.6–62.3%). ORR was 0% (95% CI, 0–24.7%), while stable disease was observed in 53.9% of patients. Median OS was 55.7 weeks (95% CI, 47.3–NE). Grade ≥3 adverse events occurred in 69.2% of patients, and grade ≥4 adverse events in 15.4%. One grade 5 event (acute-on-chronic kidney injury) was deemed unrelated to treatment. Common adverse events included hyperphosphatemia, fatigue, diarrhea, elevated transaminases, dry eye, nail changes, rash, and oral mucositis. Conclusions Futibatinib plus pembrolizumab demonstrated an acceptable safety profile but did not meet efficacy thresholds supporting further study in FGF19-expressing HCC. Effective post-immunotherapy treatment strategies remain an unmet need.

ABSTRACT Many real‐world patients with advanced biliary tract cancer (BTC) are excluded by TOPAZ‐1 criteria; this study assessed cisplatin and gemcitabine plus durvalumab (CGD) efficacy and safety in these patients. Data from 1358 patients with advanced BTC treated with first‐line CGD across 55 international centers were retrospectively analyzed. Patients were classified as TOPAZ‐1‐in (meeting all inclusion criteria) or TOPAZ‐1‐out (meeting ≥ 1 exclusion criterion). Primary endpoints were overall survival (OS) and progression‐free survival (PFS); secondary endpoints included objective response rate (ORR), disease control rate (DCR), and safety. Furthermore, OS and PFS of the TOPAZ‐1‐out cohort were compared with reconstructed survival data from the phase III trial. 912 (67.1%) patients were classified as TOPAZ‐1‐in , and 446 (32.9%) as TOPAZ‐1‐out . After a median follow‐up of 14.5 months (95% CI: 13.7–36.5), OS was 16.1 months in TOPAZ‐1‐in and 12.5 months in TOPAZ‐1‐out (HR 0.69, 95% CI: 14.6–16.5, p = 0.0001); PFS was 8.2 versus 6.5 months (HR 0.73, 95% CI: 7.1–8.1, p < 0.0001). Median OS in the TOPAZ‐1‐out cohort (12.5 months) was nearly identical to the phase III trial experimental arm (12.9 months; HR 1.15, p = 0.13); for PFS the HR was 1.12 (95% CI 0.93–1.42; p = 0.09). Among TOPAZ‐1‐out patients, active infection, elevated bilirubin, and ECOG PS > 1 were linked to poorer OS, while no detrimental impact emerged for ALT/AST abnormalities, corticosteroid use, renal or hematologic parameters, or prior surgery within 6 months, suggesting treatment effectiveness was broadly maintained across clinical subgroups. Furthermore, TOPAZ‐1‐out patients experienced no significant increase in adverse events compared with the TOPAZ‐1‐in group. Real‐world data suggest CGD may be effective in TOPAZ‐1‐out patients, with no evident increase in toxicity, supporting the potential expanded use of the regimen in clinical practice.

ABSTRACT Surgery after response to first‐line chemoimmunotherapy may offer a potential curative option for patients with locally advanced biliary tract cancer (BTC) initially considered unresectable. However, robust real‐world evidence in this setting remains limited. We retrospectively analyzed patients with locally advanced BTC treated with first‐line cisplatin, gemcitabine, and durvalumab (CGD) across 55 centers in 12 countries. Endpoints included overall survival (OS), progression‐free survival (PFS), disease‐free survival (DFS) among resected patients, objective response rate (ORR), and the prognostic impact of surgery. A multivariable logistic regression model was developed to predict surgical conversion using baseline clinical and laboratory variables. Among 1358 screened patients, 219 had locally advanced disease and were included in the analysis. Median follow‐up was 14.5 months. ORR was 34.6%, with median PFS and OS of 10.0 and 20.7 months, respectively. Twenty‐four patients (10.9%) underwent surgical resection after systemic therapy. Median OS was 22.5 months in resected patients versus 19.9 months in those who did not undergo surgery. Median DFS after resection was 15.8 months. Pathological lymph node involvement was independently associated with shorter DFS. Larger baseline tumor size correlated with higher odds of radiological response but not with OS. An exploratory elastic‐net model retained four baseline variables and showed moderate discriminative ability for surgical conversion, with an apparent AUC of 0.72 and an optimism‐corrected AUC of 0.65. First‐line CGD enabled secondary resection in approximately 11% of patients with locally advanced BTC. A simple baseline model may support patient selection for conversion surgery, although prospective validation is needed.

PURPOSE Deficient mismatch repair/microsatellite instability (dMMR, MSI-H) in biliary tract cancers (BTCs) is observed in 1%-5% of tumors. MSI-H across solid tumors has demonstrated durable response to immune checkpoint inhibitors (ICIs) regardless of the anatomic location. Here, we describe clinical outcomes and surgical conversion of MSI-H BTC treated with ICIs. Patients and Methods We conducted a multicenter, retrospective analysis of BTC patients with dMMR/MSI-H between 2017 and 2024 at Mayo Clinic, University of Michigan, and University Hospitals Seidman Cancer Center. Outcomes of interest were surgical resection rate, rate of pathologic response, 2-year overall survival (OS; time from initiation of treatment to death/last follow-up), and time to treatment discontinuation (TTD; time from initiation of treatment to cessation because of any cause). Analyses were descriptive. RESULTS Thirty patients with MSI-H BTC were identified: 19 with cholangiocarcinoma, three with gallbladder cancer, and 8 with BTC undefined. The median age at diagnosis was 61.5 years (range, 26-86). Twenty-six (86.7%) patients had advanced stage at diagnosis. Twenty-seven patients (90%) received first-line systemic therapy, and 13 (48.1%) continued onto second line. Six patients (23.1%) were restaged to resectable from advanced disease after ICI therapy and underwent resection; all remained recurrence-free at last follow-up. Of these six patients, 3 (50%) achieved a pathologic complete response. Among those receiving first-line therapy, the median TTD was 9.9 months (95% CI, 5.7 to 14.5 months) and the 2-year OS was 73% (95% CI, 56% to 94%). CONCLUSION ICI therapy in patients with MSI-H BTC demonstrated durable response and downstaged some BTC to a resectable stage. dMMR/MSI-H should be performed up-front to guide treatment decisions.

The recent approval of encorafenib, cetuximab, and FOLFOX based on the phase III BREAKWATER trial has introduced a new standard of care for the first-line treatment of BRAF V600E–mutated metastatic colorectal cancer (mCRC). However, its safety and efficacy in patients with significant liver dysfunction remains unclear and, as such, patients are often excluded from pivotal clinical trials. This report presents a case of BRAF V600E–mutated mCRC presenting with extensive hepatic involvement and liver dysfunction. Despite the absence of guidelines, the patient was initiated on full-dose encorafenib, cetuximab, and FOLFOX. He experienced a rapid clinical and biochemical response, with near-normalization of liver enzymes after cycle 1, and complete functional recovery by cycle 3. Treatment was well tolerated, with no significant adverse events throughout 9 cycles. He subsequently transitioned to maintenance 5-FU, cetuximab, and encorafenib. Posttreatment blood-based next-generation sequencing revealed no residual actionable mutations. The patient then successfully underwent complete surgical resection of his primary tumor and metastatic disease with negative margins. This case highlights the importance of considering encorafenib-based therapy in select patients with BRAF V600E–mutated mCRC in the setting of compromised liver function.

Purpose: Neuroendocrine neoplasms (NENs) are increasingly recognized to have a hereditary predilection, yet the prevalence and clinical relevance of pathogenic germline variants (PGVs) in unselected patients with NEN remain poorly defined. This prospective, multicenter study aimed to evaluate the prevalence and clinical utility of PGVs through universal multigene panel testing in a diverse cohort of patients with NENs. Patients and Methods: Between 2018 and 2024, we enrolled unselected patients with NENs from 3 Mayo Clinic Cancer Centers. Germline genetic testing was performed using a next-generation sequencing panel of up to 84 cancer predisposition genes. Patients were not selected based on age, disease stage, ethnicity, or family history. Variants were classified as PGVs, variants of uncertain significance (VUS), or negative. Clinical and demographic data were analyzed descriptively. Results: Among 88 patients, PGVs were identified in 15.9% (n=14), most frequently in high- or moderate-penetrance genes including MEN1 , CHEK2 , MITF , and MUTYH . PGVs were most commonly found in pancreatic NENs [n=12/55 (21.8%)], followed by small bowel NENs [n=2/20 (10%)], with no PGVs detected in lung NENs. Mismatch repair (MMR) gene alterations were identified in 5.7% of patients, including 1 MLH1 PGV and 4 MSH2/MSH6 VUS, 2 of which demonstrated MMR deficiency by protein testing. VUS were reported in 34.1% of patients. Notably, 35.7% of PGV-positive patients did not meet current NCCN or ACMG testing criteria, and 53.9% had PGVs in genes outside of cancer-specific guideline recommendations. Conclusions: Universal germline testing in unselected patients with NEN identified clinically relevant PGVs in over 15% of cases. These findings support broader genetic testing approaches to guide treatment, enhance familial risk assessment, and inform cascade testing—regardless of traditional clinical selection criteria.

PURPOSE Cholangiocarcinoma is a rare cancer associated with poor prognosis. Pemigatinib was the first FGFR1-3 inhibitor approved for second-line therapy and beyond, on the basis of the phase II FIGHT-202 trial. Here, we assess efficacy and safety of first-line pemigatinib. METHODS FIGHT-302 is a phase III, randomized, global trial evaluating pemigatinib as first-line therapy (ClinicalTrials.gov identifier: NCT03656536 ). Adults with advanced cholangiocarcinoma with FGFR2 rearrangement were randomized 1:1 to receive pemigatinib (13.5 mg once daily) or chemotherapy (1,000 mg/m 2 gemcitabine plus 25 mg/m 2 cisplatin once per day on days 1 and 8 of every 3-week cycle for ≤8 cycles) and were stratified by prior receipt of chemotherapy, geographic region, and tumor burden. Pemigatinib crossover was allowed for patients progressing on chemotherapy. The primary end point was progression-free survival (PFS). Secondary efficacy, safety, and exploratory end points were also analyzed. RESULTS Overall, 4,563 patients were prescreened, 196 were screened, and 167 randomly assigned to receive pemigatinib (n = 83) or chemotherapy (n = 84) before early closure of the study because of a change in standard of care. The median PFS was 8.3 months in the pemigatinib group versus 6.8 months in the chemotherapy group (hazard ratio, 0.58 [95% CI, 0.39 to 0.87]; nominal P = .0078); objective response rate was 47% versus 15%, and the median duration of response was 14.2 versus 6.3 months. Median overall survival was similar (24.4 v 25.0 months, respectively). In the crossover group (n = 42, second-line pemigatinib), the median PFS was 8.1 months. Safety was consistent with the known profile of pemigatinib. CONCLUSION To our knowledge, this was the largest, first-line, randomized, phase III trial of a targeted therapy for advanced FGFR2- rearranged cholangiocarcinoma. Pemigatinib demonstrated prolonged median PFS compared with chemotherapy, with no new safety findings.

TPS3675 Background: Multi-agent chemotherapy regimens (eg, mFOLFOX6) ± anti-vascular endothelial growth factor (VEGF) or anti-epidermal growth factor regimens are currently the standard of care for patients (pts) with mCRC without targetable mutations. However, the 5-year survival rate remains low at approximately 16% (SEER, 2025). The addition of biological therapies (eg, bevacizumab [bev], an anti-VEGF monoclonal antibody) to immune checkpoint inhibitors (ICIs) has demonstrated a synergistic antitumor effect in solid tumors. However, ICI monotherapy has limited activity in mismatch repair proficient (pMMR)/microsatellite stable (MSS) mCRC. Simultaneous bispecific targeting of programmed death 1 (PD-1) and VEGF in conjunction with cytotoxic chemotherapy has the potential to enhance antitumor activity. PF-08634404 is a fully human immunoglobulin G4 (IgG4) bispecific antibody targeting PD-1 and VEGF. A phase 2 study of PF-08634404 with XELOX or mFOLFOX6 demonstrated promising antitumor activity with a manageable safety profile in first-line (1L) mCRC (Xu X, ESMO 2025; Abstract 796P). Methods: Symbiotic-GI-03 (NCT07222800) is an ongoing, double-blind, randomized, phase 3 study evaluating the efficacy and safety of 1L PF-08634404 + mFOLFOX6 vs bev + mFOLFOX6. Inclusion criteria are age ≥18 y; mCRC with measurable disease per RECIST 1.1; no prior systemic therapy for metastatic disease; ECOG PS 0 or 1; and adequate hematologic, hepatic, and renal function. Pts with BRAF V600E-mutant or mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) CRC, active central nervous system metastases, or clinically significant risk of hemorrhage/fistula will be excluded. Approximately 800 pts will be randomized 1:1 to receive PF-08634404 + mFOLFOX6 or bev + mFOLFOX6 until disease progression, unacceptable toxicity, withdrawal of consent, or death. Randomization will be stratified by region (North America, Europe, or rest of world), RAS status (mutant or wildtype), and presence of liver metastasis (yes or no). The dual primary endpoints are progression-free survival (PFS) by blinded independent central review and overall survival; for each, a stratified log-rank test will be used to compare arms. Hazard ratios with corresponding 2-sided 95% CIs will be estimated using a stratified Cox proportional hazards model, and medians will be estimated using the Kaplan-Meier method with corresponding 2-sided 95% CIs calculated using the log(-log) method. Secondary endpoints include PFS by investigator, objective response rate, duration of response, PFS after next-line therapy, safety/tolerability, pharmacokinetics, immunogenicity, and patient-reported outcomes. Enrollment began in December 2025. Clinical trial information: NCT07222800 .

e16377 Background: 1L systemic treatment of mPDAC can lead to severe adverse events (AEs). To contextualize the safety profile of irinotecan-based regimens, real-world data were used to characterize AEs and their management in patients receiving 1L mPDAC treatment with FOLFIRINOX (FFX) or gemcitabine+Nab-paclitaxel (Gem+NabP). Methods: De-identified data from Mayo Clinic electronic health records (all sites; records collected 2010–2023) were used. Natural language processing was leveraged to confirm staging and metastatic classification and to extract treatment data. Adults with mPDAC with stage IV and/or TNM staging of M1 who received ≥ 1 dose of FFX or Gem+NabP were included. Primary endpoint: proportion of patients with AEs of interest (diarrhea, nausea, vomiting, neuropathy, and neutropenia) following initiation of 1L treatment. Secondary endpoints: proportion of patients who received treatment for each AE of interest, median time to resolution and treatment of each AE of interest, and proportion of patients who switched mPDAC treatment or had dose reductions due to AEs. Results: In total, 405 patients (FFX, 197; Gem+NabP, 208) were identified. The proportions of patients who experienced and were treated for any-grade AEs of interest are reported in the Table. Of the AEs of interest, neutropenia resolved most quickly (median time from onset to resolution, FFX: 9.5 days; Gem+NabP: 12.5 days); neuropathy took the longest time to resolve (FFX: 44.0 days; Gem+NabP: 74.0 days). Median time to AE treatment was shortest for nausea and vomiting (both 0.0 days for FFX and for Gem+NabP). Time to treatment was longest for neuropathy (FFX: 158.5 days; Gem+NabP: 70.0 days). Only 5.1% of patients on FFX and 13.4% on Gem+NabP received treatment for neuropathy. Of patients in the FFX group who switched/reduced treatment (n=140), 58.6% received a dose reduction and 7.1% switched to Gem+NabP due to AEs. Conclusions: At the Mayo Clinic sites, incidence of any-grade AEs associated with 1L mPDAC treatment were similar or higher than rates of any-grade or ≥ 2/3–4 grade AEs reported in the literature. Nausea, vomiting and diarrhea were the most commonly treated AEs for both irinotecan-based (FFX) and non-irinotecan-based (Gem+NabP) 1L regimens; neutropenia and neuropathy were less commonly treated. FFX dose reductions were commonly attempted before switching regimens. Proportion experiencing any-grade AE (AE incidence in the literature) Proportion experiencing AE treated for an AE FFX Gem+NabP FFX Gem+NabP Diarrhea 74.6% (50–80%, any grade) 43.8% (< 5%, any grade) 92.5% 56.0% Nausea 81.7% (45%, any grade) 72.1% (20%, grade ≥ 2) 98.8% 96.7% Vomiting 54.8% (10%, any grade) 42.8% (20%, grade ≥ 2) 98.1% 98.9% Neutropenia 58.9% (45%, grade 3–4) 48.1% (12–21%, grade 3–4) 62.1% 46.0% Neuropathy 59.9% (25%, grade 3–4) 32.2% (30%, grade 3–4) 5.1% 13.4%

4219 Background: Pancreatic ductal adenocarcinoma (PDAC) remains a notoriously difficult-to-treat malignancy, with limited therapy options for patients with advanced disease. While KRAS mutations are the dominant oncogenic driver in PDAC, next-generation sequencing has enabled the identification of rare, targetable alterations such as the BRAF V600E mutation, which occurs in approximately 2-3% of cases. BRAF mutant cell lines are responsive to MEK and RAF inhibitors. This study evaluates the efficacy of the combination of encorafenib and binimetinib as ≥ 2nd line therapy in this specific molecular subgroup of pancreatic cancer patients. Methods: This study used a planned two-stage design. Seven patients were pre-registered; one did not meet eligibility criteria and was excluded. Six patients were enrolled in Stage 1, which required an objective response (OR) in 40% of patients to proceed to Stage 2. Stage 2 was planned to enroll an additional 16 patients, contingent on meeting this efficacy threshold. Enrolled patients received treatment in 28-day cycles until disease progression or for a maximum of 36 cycles. Patients self-administered encorafenib (450 mg orally once daily) and binimetinib (45 mg orally twice daily) starting on Day 1 of each cycle. Objective responses were assessed using RECIST version 1.1 over 24 weeks. Results: The median number of cycles was 8. The objective response rate at 24 weeks was 33.33%. The overall objective response rate was 50%. The median time to response for progression-free survival, overall survival, duration of response, and time to response was 7.1, 15.0, 9.9, and 3.9 months respectively, with 95% CI in all categories. 50% of patients experienced at least one Grade ≥3 adverse event, including anemia, thromboembolic events, and acute kidney injury. Conclusions: The six BRAF-V600E-mutated PDAC patients in our cohort demonstrated meaningful antitumor activity with a manageable safety profile after treatment with encorafenib and binimetinib. Although the study was prematurely terminated due to limited accrual, observed objective responses and survival outcomes suggest that dual RAF/MEK inhibition may represent a feasible therapeutic strategy in this rare molecular subgroup. Larger studies are warranted to further define the efficacy and safety of this treatment combination in BRAF-V600E-mutated pancreatic cancer. Clinical trial information: NCI-2020-02972 .