Lynch Syndrome and Somatic Mismatch Repair Variants in Pancreas Cancer.

Importance: Microsatellite (MS) instability (MSI-H) occurs frequently in Lynch syndrome (LS)-associated tumors and is associated with response to immune checkpoint blockade (ICB) therapy. MSI-H is conferred by germline or somatic variants in mismatch repair genes. The contribution of somatic oncogenesis to MSI-H in pancreatic cancer (PC) is unknown. Objective: To evaluate an LS-related PC cohort to define clinicogenomic features, describe somatic MSI-H cases (germline negative), characterize response to ICB, and guide preferred MS testing methods. Design, Setting, and Participants: This single-institution, retrospective analysis was conducted from March 2012 to July 2023 at Memorial Sloan Kettering Cancer Center and included 55 patients with PC and either an LS germline pathogenic variant (gPV) or somatic mismatch repair (MMR) variant. Main Outcomes and Measures: Composite MMR and MS status determined using orthogonal methods. An artificial intelligence classifier was used to account for low-cellularity specimens. Demographic and clinical data were abstracted from medical record. Zygosity status and somatic comutation landscape analyzed. Results: Fifty-five patients (23 women [42%]) had PC and an MMR variant: 32 (58%) had LS (LS cohort) and 23 (42%) had a somatic MMR variant (no germline pathogenic variant, somatic MMR cohort). In the LS cohort, 10 (31%) had gMSH2, 9 (28%) gMSH6, 8 (25%) gPMS2, 4 (13%) gMLH1, 1 (3%) gEPCAM. The median age at diagnosis was 68 years (range, 45-88 years). For composite MS status, 17 (59%) were MSI-H, 12 (41%) MS stable, and 3 MS unknown. Five cases were reclassified as MSI-H by the artificial intelligence classifier. In the somatic MMR cohort, 11 (48%) had MSH6, 7 (30%) MLH1, 3 (13%) MSH2, and 2 (9%) PMS2. The median age at diagnosis was 72 years (range, 66-85 years). For composite MS status, 10 (43%) were MSI-H, 11 (48%) MS stable, and 2 (9%) MS indeterminate. Six cases were reclassified as MSI-H by the artificial intelligence classifier. For the LS and somatic MMR cohorts, 20 received ICB (n = 17 MSI-H). The median ICB duration was 27.7 months (95% CI, 11.5 to not reached); the disease control rate was 80%. Conclusion: The results of this cross-sectional study suggest that MSI-H occurs due to LS or somatic oncogenesis in PC. Orthogonal MS testing is key in PC; the artificial intelligence classifier reclassified approximately 20% of cases, most of which were low cellularity. ICB for patients with LS or somatic MSI-H PC provided significant benefit.

Precision medicine for pancreatic cancer: characterizing the clinicogenomic landscape and outcomes of KRAS G12C-mutated disease.

BACKGROUND: Mutated Kirsten rat sarcoma viral oncogene homolog (KRAS) is the most common oncogene alteration in pancreatic ductal adenocarcinoma, and KRAS glycine to cystine substitution at codon 12 (G12C) mutations (KRAS G12Cmut) are observed in 1%-2%. Several inhibitors of KRAS G12C have recently demonstrated promise in solid tumors, including pancreatic cancer. Little is known regarding clinical, genomics, and outcome data of this population. METHODS: Patients with pancreatic cancer and KRAS G12Cmut were identified at Memorial Sloan Kettering Cancer Center and via the American Association of Cancer Research Project Genomics, Evidence, Neoplasia, Information, Exchange database. Clinical, treatment, genomic, and outcomes data were analyzed. A cohort of patients at Memorial Sloan Kettering Cancer Center with non-G12C KRAS pancreatic cancer was included for comparison. RESULTS: Among 3571 patients with pancreatic ductal adenocarcinoma, 39 (1.1%) with KRAS G12Cmut were identified. Median age was 67 years, and 56% were female. Median body mass index was 29.2 kg/m2, and 67% had a smoking history. Median overall survival was 13 months (95% CI: 9.4 months, not reached) for stage IV and 26 months (95% CI: 23 months, not reached) for stage I-III. Complete genomic data (via American Association of Cancer Research Project Genomics, Evidence, Neoplasia, Information, Exchange database) was available for 74 patients. Most common co-alterations included TP53 (73%), CDKN2A (33%), SMAD4 (28%), and ARID1A (21%). Compared with a large cohort (n = 2931) of non-G12C KRAS-mutated pancreatic ductal adenocarcinoma, ARID1A co-mutations were more frequent in KRAS G12Cmut (P < .05). Overall survival did not differ between KRAS G12Cmut and non-G12C KRAS pancreatic ductal adenocarcinoma. Germline pathogenic variants were identified in 17% of patients; 2 patients received KRAS G12C-directed therapy. CONCLUSION: Pancreatic cancer and KRAS G12Cmut may be associated with a distinct clinical phenotype. Genomic features are similar to non-G12C KRAS-mutated pancreatic cancer, although enrichment of ARID1A co-mutations was observed. Targeting of KRAS G12C in pancreatic cancer provides a precedent for broader KRAS targeting in pancreatic cancer.

Africa Guidelines for Hepatocellular Carcinoma Buildup Process.

PURPOSE: Hepatocellular carcinoma (HCC), the fourth most common cancer in Africa, has a dismal overall survival of only 3 months like in sub-Saharan Africa. This is affected by the low gross domestic product and human development index, absence of coherent guidelines, and other factors. METHODS: An open forum for HCC-experienced health care workers from Africa and the rest of the world was held in October 2021. Participants completed a survey to help assess the real-life access to screening, diagnoses, and treatment in the North and Southern Africa (NS), East and West Africa (EW), Central Africa (C), and the rest of the world. RESULTS: Of 461 participants from all relevant subspecialties, 372 were from Africa. Most African participants provided hepatitis B vaccination and treatment for hepatitis B and C. More than half of the participants use serum alpha-fetoprotein and ultrasound for surveillance. Only 20% reported using image-guided diagnostic liver biopsy. The Barcelona Clinic Liver Cancer is the most used staging system (52%). Liver transplant is available for only 28% of NS and 3% EW. C reported a significantly lower availability of resection. Availability of local therapy ranged from 94% in NS to 62% in C. Sorafenib is the most commonly used systemic therapy (66%). Only 12.9% reported access to other medications including immune checkpoint inhibitors. Besides 42% access to regorafenib in NS, second-line treatments were not provided. CONCLUSION: Similarities and differences in the care for patients with HCC in Africa are reported. This reconfirms the major gaps in access and availability especially in C and marginally less so in EW. This is a call for concerted multidisciplinary efforts to achieve and sustain a reduction in incidence and mortality from HCC in Africa.

Clinico-genomic Characterization of ATM and HRD in Pancreas Cancer: Application for Practice.

PURPOSE: Characterizing germline and somatic ATM variants (gATMm, sATMm) zygosity and their contribution to homologous recombination deficiency (HRD) is important for therapeutic strategy in pancreatic ductal adenocarcinoma (PDAC). EXPERIMENTAL DESIGN: Clinico-genomic data for patients with PDAC and other cancers with ATM variants were abstracted. Genomic instability scores (GIS) were derived from ATM-mutant cancers and overall survival (OS) was evaluated. RESULTS: Forty-six patients had PDAC and pathogenic ATM variants including 24 (52%) stage III/IV: gATMm (N = 24), and sATMm (N = 22). Twenty-seven (59%) had biallelic, 15 (33%) monoallelic, and 4 indeterminate (8%) variants. Median OS for advanced-stage cohort at diagnosis (N = 24) was 19.7 months [95% confidence interval (CI): 12.3-not reached (NR)], 27.1 months (95% CI: 22.7-NR) for gATMm (n = 11), and 12.3 months for sATMm (n = 13; 95% CI: 11.9-NR; P = 0.025). GIS was computed for 33 patients with PDAC and compared with other ATM-mutant cancers enriched for HRD. The median was lower (median, 11; range, 2-29) relative to breast (18, 3-55) or ovarian (25, 3-56) ATM-mutant cancers (P < 0.001 and P = 0.003, respectively). Interestingly, biallelic pathogenic ATM variants were mutually exclusive with TP53. Other canonical driver gene (KRAS, CDKN2A, SMAD4) variants were less frequent in ATM-mutant PDAC. CONCLUSIONS: ATM variants in PDAC represent a distinct biologic group and appear to have favorable OS. Nonetheless, pathogenic ATM variants do not confer an HRD signature in PDAC and ATM should be considered as a non-core HR gene in this disease.

Oral Squamous Cell Carcinoma as a Complication of Treatment for Recurrent High-Grade Serous Cancer.

OBJECTIVES/HYPOTHESIS: Advances in cancer treatment have increased survival for many patients, prompting a need for greater recognition of the long-term complications of treatment. Chemotherapy agents have the potential to induce carcinogenesis and can increase the risk of secondary malignancy. Pegylated liposomal doxorubicin (PLD) used for maintenance treatment of recurrent high-grade serous cancers has been associated with the development of oral cavity squamous cell carcinoma (SCC). STUDY DESIGN: Retrospective review. METHODS: Cases of oral cavity SCC in patients with recurrent high-grade serous cancer treated with PLD between 1997 and 2017 at a single institution were reviewed. RESULTS: Eight of 16 patients treated with PLD developed oral cavity SCC. The duration of PLD use ranged from 1.3 to 15 years (mean = 5.8 years) and cumulative dose ranged from 405 to 3,000 mg/m2 (mean = 1,542 mg/m2 ). Seven patients tested positive for BRCA mutations (four BRCA 1+, three BRCA 2+). No patients had a history of alcohol or tobacco use. All had early-stage oral cavity disease; five were T1N0, two were T2N0, and one had carcinoma in situ. All patients underwent surgery, and two received adjuvant radiation. Four developed locoregional recurrence requiring additional treatment. Of these, one patient died from complications of oral SCC, one developed recurrent ovarian cancer, and two had no evidence of disease of the oral cavity or ovarian cancer at the last follow-up. CONCLUSIONS: Long-term PLD therapy may be associated with the development of oral cavity SCC. A high index of suspicion and routine head and neck examination should be included in follow-up for exposed patients. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:2607-2610, 2020.

DNA resection proteins Sgs1 and Exo1 are required for G1 checkpoint activation in budding yeast.

Double-strand breaks (DSBs) in budding yeast trigger activation of DNA damage checkpoints, allowing repair to occur. Although resection is necessary for initiating damage-induced cell cycle arrest in G2, no role has been assigned to it in the activation of G1 checkpoint. Here we demonstrate for the first time that the resection proteins Sgs1 and Exo1 are required for efficient G1 checkpoint activation. We find in G1 arrested cells that histone H2A phosphorylation in response to ionizing radiation is independent of Sgs1 and Exo1. In contrast, these proteins are required for damage-induced recruitment of Rfa1 to the DSB sites, phosphorylation of the Rad53 effector kinase, cell cycle arrest and RNR3 expression. Checkpoint activation in G1 requires the catalytic activity of Sgs1, suggesting that it is DNA resection mediated by Sgs1 that stimulates the damage response pathway rather than protein-protein interactions with other DDR proteins. Together, these results implicate DNA resection, which is thought to be minimal in G1, as necessary for activation of the G1 checkpoint.

Mutations in a gene encoding a novel protein containing a phosphotyrosine-binding domain cause type 2 cerebral cavernous malformations.

Cerebral cavernous malformations (CCMs) are congenital vascular anomalies of the central nervous system that can result in hemorrhagic stroke, seizures, recurrent headaches, and focal neurologic deficits. Mutations in the gene KRIT1 are responsible for type 1 CCM (CCM1). We report that a novel gene, MGC4607, exhibits eight different mutations in nine families with type 2 CCM (CCM2). MGC4607, similar to the KRIT1 binding partner ICAP1alpha, encodes a protein with a phosphotyrosine-binding domain. This protein may be part of the complex pathway of integrin signaling that, when perturbed, causes abnormal vascular morphogenesis in the brain, leading to CCM formation.