Gastroesophageal adenocarcinoma (GEA) is a lethal disease where targeted therapies, even when guided by genomic biomarkers, have had limited effi cacy. A potential reason for the failure of such therapies is that genomic profi ling results could commonly differ between the primary and metastatic tumors. To evaluate genomic heterogeneity, we sequenced paired primary GEA and synchronous metastatic lesions across multiple cohorts, fi nding extensive differences in genomic alterations, including discrepancies in potentially clinically relevant alterations. Multiregion sequencing showed signifi cant discrepancy within the primary tumor (PT) and between the PT and disseminated disease, with oncogene amplifi cation profi les commonly discordant. In addition, a pilot analysis of cell-free DNA (cfDNA) sequencing demonstrated the feasibility of detecting genomic amplifi cations not detected in PT sampling. Lastly, we profi led paired primary tumors, metastatic tumors, and cfDNA from patients enrolled in the personalized antibodies for GEA (PANGEA) trial of targeted therapies in GEA and found that genomic biomarkers were recurrently discrepant between the PT and untreated metastases. Divergent primary and metastatic tissue profi ling led to treatment reassignment in 32% (9/28) of patients. In discordant primary and metastatic lesions, we found 87.5% concordance for targetable alterations in metastatic tissue and cfDNA, suggesting the potential for cfDNA profi ling to enhance selection of therapy. SIGNIFICANCE:We demonstrate frequent baseline heterogeneity in targetable genomic alterations in GEA, indicating that current tissue sampling practices for biomarker testing do not effectively guide precision medicine in this disease and that routine profi ling of metastatic lesions and/or cfDNA should be systematically evaluated. Cancer Discov; 8(1);[37][38][39][40][41][42][43][44][45][46][47][48]

Previous anti-EGFR trials in unselected gastroesophageal adenocarcinoma (GEA) patients were resoundingly negative. We identified EGFR amplification in 5% (19/363) of patients at the University of Chicago, including 6% (8/140) who were prospectively screened with intention-to-treat using anti-EGFR therapy. Seven pts received >1 dose of treatment: three first line FOLFOX plus ABT-806, one second line FOLFIRI plus cetuximab, and three third/fourth line cetuximab alone. Treatment achieved objective response in 58% (4/7) and disease control in 100% (7/7) with a median progression-free survival of 10 months. Pre and post-treatment tumor NGS, serial plasma ctDNA NGS, and tumor IHC/FISH for EGFR revealed pre-existing and/or acquired genomic events including EGFR negative clones, PTEN deletion, KRAS amplification/mutation, NRAS, MYC and HER2 amplification, and GNAS mutations serving as mechanisms of resistance. Two evaluable patients demonstrated interval increase of CD3+ infiltrate, including one who demonstrated increased NKp46+, and PD-L1 IHC expression from baseline, suggesting an immune therapeutic mechanism of action. EGFR amplification predicted benefit from anti-EGFR therapy, albeit until various resistance mechanisms emerged. Statement of Significance: This paper highlights the role of EGFR inhibitorsin EGFR amplified GEA -despite negative results in prior unselected phase III trials. Using serial ctDNA and tissue NGS, we identified mechanisms of primary and acquired resistance in all patients, as well as potential contribution of antibody-dependent cell-mediated cytotoxicity (ADCC) to their clinical benefit.

This cohort study provides valuable insights into the characteristics of HCC in Korean patients. Our findings may help develop clinical trials, treatment strategies, and prognosis systems for HCC patients in HBV-endemic areas.

Previous studies have shown a correlation between pre-transplant conditioning intensity, intestinal barrier loss, and graft-versus-host disease (GVHD) severity. However, since irradiation and other forms of pre-transplant conditioning have pleiotropic effects, the precise role of intestinal barrier loss in GVHD pathogenesis remains unclear. We developed GVHD models that allowed us to isolate the specific contributions of distinct pre-transplant variables. First, intestinal damage was required for the induction of minor mismatch (MHC-matched) GVHD, but was not necessary for major mismatch GVHD, demonstrating fundamental pathogenic distinctions between these forms of disease. Moreover, recipient NK cells prevented minor mismatch GVHD by limiting expansion and target organ infiltration of alloreactive T cells via a perforin-dependent mechanism, revealing a previously unrecognized immunoregulatory function of recipient NK cells in GVHD. Minor mismatch GVHD required MyD88-mediated TLR4 signaling on donor cells, and intestinal damage could be bypassed by parenteral LPS administration, indicating a critical role for the influx of bacterial components triggered by intestinal barrier loss. In all, the data demonstrate that pre-transplant conditioning plays a dual role in promoting minor mismatch GVHD by both depleting recipient NK cells and inducing intestinal barrier loss.

Most GCs in Korea without current Hp infection showed evidence of past Hp infection. The proportion of GCs with diffuse-type histology decreased in patients with past infection.