Citations

Abstract Background: Early-onset gastrointestinal (GI) cancers are increasing globally, yet the genomic basis for age-related differences across multiple tumor types remains poorly defined. We leveraged AACR Project GENIE v18.0 (N≈34,000 GI tumors) to characterize molecular distinctions by age in colorectal, pancreatic, small bowel, and anal cancers with sufficient early-onset representation. Methods: Clinical and genomic data were extracted and tumors classified into early-onset (<50 years) and late-onset (≥50 years). Mutation frequencies were compared by cancer type and age group, focusing on recurrent drivers, DNA repair, Wnt signaling, RAS/MAPK, chromatin remodeling genes, and targetable alterations. Results: Early-onset colorectal cancer (N=5,724) showed increased Wnt/β-catenin pathway alterations: APC (+4.9%), TCF7L2 (+4.1%), and TP53 (+5.0%), while late-onset tumors (N=15,807) were enriched for BRAF (−5.4%), RNF43 (−1.9%), and GNAS (−1.1%), indicating divergent tumorigenic pathways. Early-onset pancreatic cancer (N=890) exhibited significantly lower frequencies of canonical drivers—KRAS (−24.7%), TP53 (−15.6%), CDKN2A (−6.9%), SMAD4 (−6.0%)—with enrichment of MEN1 (+3.5%), TSC2 (+3.0%), ATRX (+2.0%), DAXX (+1.9%), and CTNNB1 (+2.4%), consistent with fusion-driven, hereditary, and chromatin remodeling biology. Small bowel cancer (N=99) in early-onset patients demonstrated enrichment in DNA damage response and MAPK/RAS genes including BRCA2 (+7.2%), NF1 (+7.4%), FBXW7 (+8.8%), FLT4 (+6.5%), ARAF (+6.4%), and ALK (+5.1%), whereas late-onset tumors (N=538) were enriched for KDR (−5.1%) and MGA (−5.2%). Early-onset anal cancer (N=62) showed elevated MGA (+7.8%), WHSC1/NSD2 (+6.9%), PBRM1 (+6.2%), FANCA (+5.2%), ERCC5 (+6.2%), and MSH6 (+5.9%), highlighting chromatin remodeling and DNA repair pathways potentially related to HPV biology; late-onset tumors (N=464) had enrichment in ATM (−5.6%), PTEN (−5.5%), STK11 (−5.2%), APC (−5.2%), and KMT2C (−5.0%), reflecting age-associated genomic instability. Conclusions: This pan-GI age-stratified analysis reveals distinctive oncogenic programs in early-onset GI cancers characterized by Wnt/TP53-driven colorectal, fusion- and chromatin remodeling-driven pancreatic, DNA damage response/MAPK-driven small bowel, and chromatin-immune DDR signatures in anal cancers. These findings underscore the need for age-tailored precision oncology and support routine genomic profiling in early-onset GI malignancies to identify targetable alterations enriched in younger patients. Citation: AACR Project GENIE Consortium. AACR Project GENIE: Powering Precision Medicine Through an International Consortium. Cancer Discov. 2017;7(8):818-831. (Data: GENIE Release 18.0-public)Acknowledgement: AACR and Project GENIE registry Citation Format: Ahmed Abdelhakeem, Nency Ganatra, Dina Elantably, Tayo Adeoye, Nayef H. Abdel-Razeq, Mosalem M. Osama, Hani M. Babiker. Distinct age associated genomic landscapes in colorectal, pancreatic, small bowel, and anal cancers: A pan gastrointestinal analysis of 34,000 tumors from AACR Project GENIE v18.0 [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 4105.

Abstract Background: PARP inhibitors are restricted to a subset of BRCA-associated cancers, but homologous recombination repair (HRR) deficiency signifies a broader genomic vulnerability that may extend therapeutic opportunities across diverse malignancies. We utilized AACR Project GENIE v18.0-public to define the pan-cancer prevalence of HRR gene alterations. Methods: Somatic mutation and clinical sample data from GENIE v18.0-public were analyzed. HRR genes included BRCA1, BRCA2, ATM, CHEK2, PALB2, RAD51B/C/D, RAD51L1, BARD1, BRIP1, and core FANC genes. HRR alteration rates were calculated by tumor type using unique samples; only de-identified aggregate results are reported. Results: Among 101,240 tumors, HRR gene alterations were frequent in multiple non-BRCA-associated cancers. Highest rates were seen in sialoblastoma (100%), large cell medulloblastoma (50%), malignant glomus tumor (50%), lung cancer (46.0%), infantile fibrosarcoma (42.9%), liver (40%), kidney (40%), non-melanoma skin (36.9%), colorectal (36.6%), melanocytoma (34.2%), biliary tract (33.3%), bladder (31.5%), and ovarian/fallopian tube (30.2%). Notably, lung, bladder, hepatobiliary, renal, gastrointestinal, and some sarcoma subtypes showed HRR mutation prevalence equal or higher than current PARP indications, yet lack FDA approval. Conclusions: HRR alterations are widespread across solid tumors, often surpassing rates in cancers eligible for PARP treatment. These findings support expanding tumor-agnostic HRR genomic testing beyond BRCA-linked malignancies and warrant prospective trials of PARP inhibitors in HRR-enriched tumor types such as lung, bladder, hepatobiliary, renal, gastrointestinal, and pediatric/rare cancers. Impact: Large-scale genomic profiling from AACR Project GENIE demonstrates that HRR gene alterations are common across diverse solid tumors, with prevalence in multiple cancer types surpassing those currently eligible for PARP inhibitor therapy. These findings support broad implementation of HRR genomic testing in routine molecular diagnostics and provide a rationale for expanding PARP inhibitor use beyond BRCA-associated malignancies. The data justify prospective tumor-agnostic clinical trials of PARP inhibitors in HRR-enriched cancers such as lung, bladder, hepatobiliary, renal, gastrointestinal, and select pediatric and rare tumors; this could transform therapeutic decision-making and accelerate development of synthetic lethality-based targeted therapies Citation: AACR Project GENIE Consortium. Cancer Discov. 2017;7(8):818-831 Acknowledgement: AACR and Project GENIE Citation Format: Ahmed Abdelhakeem, Nency Ganatra, Dina Elantably, Tayo Adeoye, Nayef H. Abdel-Razeq, Osama M. Mosalem, Hani M. Babiker. Pan cancer enrichment of homologous recombination repair (HRR) gene alterations in 101,240 tumor samples from AACR Project GENIE: Implications for tumor-agnostic PARP inhibitor expansion [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 4106.

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.

Liver transplantation has emerged as a curative treatment option for selected patients with unresectable hepatic malignancies beyond hepatocellular carcinoma, marking a paradigm shift in transplant oncology. For colorectal cancer liver metastases (CRLM), prospective trials have demonstrated that highly selected patients achieve 5-year OS rates of 60–83%, with the Oslo score identifying optimal candidates for transplantation. Perihilar cholangiocarcinoma (pCCA) has been successfully treated using strict patient selection criteria combined with neoadjuvant therapy, achieving 5-year OS rates of 50–68%, though emerging data suggests chemotherapy-based approaches may be preferable to radiation in selected cases. Intrahepatic cholangiocarcinoma (iCCA), previously considered a contraindication to transplantation, can now achieve excellent long-term outcomes (79.5% 5-year OS) in patients demonstrating sustained response to neoadjuvant chemotherapy and radioembolization, with metabolic tumor volume < 70 cm3 serving as an objective prognostic marker. Across these three emerging indications, successful outcomes depend on strict patient selection based on tumor biology, intensive multimodal neoadjuvant therapy, multidisciplinary evaluation in high-volume centers, and careful observation during treatment to exclude patients with aggressive disease. This evolution in transplant practice offers curative intent therapy to patients that previously only had palliative therapeutic options, fundamentally transforming hepatobiliary and oncologic surgery.

Anal squamous cell carcinoma (ASCC) is a rare malignancy of the lower gastrointestinal tract, with distant metastases typically involving the liver and lungs. Metastasis to the kidneys is uncommon, and only one prior case has been reported in the literature. Herein, we report a rare presentation of a patient with biopsy-confirmed metastatic ASCC presenting as bilateral renal lesions. We then provide a review of the literature for rare metastatic presentations of ASCC, highlighting all the cases described in the literature. Clinicians should maintain a high index of suspicion for unusual metastatic sites, perform targeted imaging and biopsy when indicated, and consider systemic therapies to optimize outcomes in rare metastatic presentations.

741 Background: IP strategies directly target the peritoneal compartment in PDAC, where systemic chemotherapy alone demonstrates poor efficacy. Approaches include HIPEC, normothermic intraperitoneal paclitaxel (NIPEC/IP-PTX) given with systemic therapy, and PIPAC. This systematic review synthesizes evidence on feasibility, perioperative safety, and clinical outcomes of IP therapy in PDAC. Methods: We conducted a systematic search in PubMed, Embase, Scopus, and Cochrane databases for studies published through August 2025. Eligible studies included prospective or retrospective studies evaluating HIPEC, NIPEC/IP-PTX, or PIPAC with extractable safety or oncologic outcomes. Outcomes included feasibility, 30-day mortality, perioperative complications, locoregional recurrence (LRR) in the adjuvant setting, overall survival (OS) from peritoneal metastasis (PM) diagnosis or first IP therapy, conversion-to-resection, and histologic/radiologic response. Results: Sixteen studies met criteria, including 7 on HIPEC, 5 on NIPEC/IP-PTX, and 4 on PIPAC. In the adjuvant setting, 2 HIPEC studies demonstrated high feasibility (>85%), 0–5% 30-day mortality, and complication rates comparable to pancreatectomy. A randomized trial reported significantly lower LRR with adjuvant gemcitabine HIPEC. Median OS in treated arms was ~17–18 months, with 1-year OS ~63%. In the cytoreductive surgery (CRS) plus HIPEC setting for isolated peritoneal metastases, patients achieved CC-0/1 cytoreduction in most cases, with median OS ~24–41 months and 1-, 2-, and 3-year OS ranging 60–91%, 33–66%, and 39–59%, respectively. Thirty-day mortality was 0–4.3%, and major morbidity 20–43%. For NIPEC/IP-PTX, multicenter and single-institution cohorts consistently reported median OS ~14–16 months, 1-year OS ~60%, and conversion-to-resection rates of 17–24%. Ascites control and feasibility were reproducible, and device-related adverse events were generally manageable. PIPAC programs established oxaliplatin at 120 mg/m² as the recommended dose, with ~50–60% histologic regression by PRGS and disease stabilization in 50–60% after 1–2 cycles. Median OS in PDAC subsets was ~9–13 months, with low major toxicity, though early discontinuation was frequent in progressive disease. Conclusions: Intraperitoneal therapies for PDAC are feasible and show promising biologic and clinical signals. Adjuvant HIPEC reduces locoregional recurrence without excess mortality; CRS plus HIPEC can achieve multi-year survival in selected patients with isolated PM metastases; NIPEC/IP-PTX offers reproducible survival and conversion-to-resection; and PIPAC provides histologic regression with acceptable safety.

117 Background: Oxaliplatin remains a cornerstone of colorectal cancer (CRC) chemotherapy but is frequently complicated by chemotherapy-associated liver injury (CALI). This manifests as sinusoidal obstruction syndrome (SOS), nodular regenerative hyperplasia (NRH), or porto-sinusoidal vascular disorder (PSVD). These microvascular changes lead to portal hypertension (PH), splenomegaly, and thrombocytopenia, interrupting chemotherapy delivery and compromising survivorship. Despite increasing recognition, the incidence, spectrum, and management of oxaliplatin-induced portal hypertension (OIPH) remain undefined. Methods: We systematically reviewed PubMed, Embase, and Cochrane through August 2025 for prospective and retrospective cohorts of oxaliplatin-treated CRC patients reporting OIPH incidence, pathology, radiology, or interventional management. Case reports were excluded. Outcomes included incidence, latency, complications, misdiagnosis, and interventions such as bevacizumab and partial splenic embolization (PSE). Results: Eight studies including 730 patients were analyzed. OIPH developed in ~20–30% of patients, with 2–5% progressing to clinically overt disease requiring variceal banding, Transjugular Intrahepatic Portosystemic Shunt (TIPS), PSE, or management of liver failure. Latency to presentation was typically 4–10 years after oxaliplatin exposure. Common features included splenomegaly, thrombocytopenia, varices, and ascites. Histopathology consistently showed sinusoidal dilatation, congestion, perisinusoidal fibrosis, NRH, and microthrombi, confirming endothelial-mediated injury. Up to half of chronic cases were misclassified as metabolic dysfunction–associated steatotic liver disease (MASLD/NAFLD) or cryptogenic cirrhosis. Bevacizumab demonstrated consistent hepatoprotection, delaying splenic enlargement and reducing thrombocytopenia, likely via preservation of sinusoidal endothelial integrity and reduction of von Willebrand factor–mediated platelet microthrombi. Interventional radiology provided therapeutic options: in a prospective phase II study, PSE restored platelet counts >130×10⁹/L in 94% and enabled chemotherapy resumption within a median of 14 days, with no grade ≥3 adverse events. Conclusions: OIPH is an under-recognized complication of CRC chemotherapy, with latency spanning years after treatment. Splenomegaly and thrombocytopenia serve as early clinical signals, while misdiagnosis as MASLD or cirrhosis is common. Bevacizumab provides hepatoprotection, and PSE offers a safe and effective option for chemotherapy-limiting thrombocytopenia. Routine monitoring of spleen volume and platelet trends should be integrated into follow-up, and prospective validation of prophylactic and interventional strategies is urgently needed.

Background: Peritoneal metastasis represents an aggressive disease pattern in pancreatic ductal adenocarcinoma (PDAC), traditionally associated with poor survival and limited therapeutic options. Emerging intraperitoneal chemotherapy strategies—including hyperthermic intraperitoneal chemotherapy (HIPEC), normothermic intraperitoneal paclitaxel (NIPEC/IP-PTX), and pressurized intraperitoneal aerosol chemotherapy (PIPAC)—have been investigated to improve local tumor control and survival outcomes. Methods: We systematically reviewed published studies evaluating HIPEC, NIPEC/IP-PTX, and PIPAC in PDAC, including adjuvant, cytoreductive, and palliative settings. Study characteristics, feasibility, perioperative outcomes, oncologic outcomes, and risk of bias were analyzed. Results: Across modalities, intraperitoneal treatment strategies demonstrated acceptable feasibility and safety profiles in appropriately selected patients. Adjuvant HIPEC following pancreatectomy showed reduced local–regional recurrence signals in limited cohorts. CRS + HIPEC among patients with isolated peritoneal metastases yielded encouraging multi-year survival in highly selected candidates achieving complete cytoreduction. NIPEC/IP-PTX demonstrated favorable ascites control, symptom relief, and potential conversion to resection in select patients. PIPAC was primarily used in unresectable, heavily pretreated, palliative peritoneal metastasis settings, with goals centered on disease stabilization, histologic regression, and symptom control rather than curative intent. Conclusions: Intraperitoneal chemotherapy strategies in PDAC appear feasible with signals of meaningful clinical benefit in select settings. While CRS + HIPEC may benefit carefully selected metastatic patients, NIPEC/IP-PTX and PIPAC hold value primarily in symptom control and disease stabilization. Larger prospective trials are needed to define patient selection, optimize treatment protocols, and clarify survival benefit.