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PURPOSE: Panel-based comprehensive genomic profiling (CGP) is used in clinical practice worldwide; however, large real-world data (RWD) of patients with advanced small intestine cancer have not been characterized. We investigated differences in the prevalence of clinically relevant alterations across molecularly defined or age-stratified subgroups. PATIENTS AND METHODS: This was a collaborative biomarker study of RWD from CGP testing (Foundation Medicine, Inc). Hybrid capture was conducted on at least 324 cancer-related genes and select introns from up to 31 genes frequently rearranged in cancer. Overall, 1,364 patients with advanced small intestine cancer were available for analyses and were stratified by age (≥40 years/<40 years), microsatellite instability (MSI) status, tumor mutational burden (TMB) status (high ≥10/low <10 Muts/Mb), and select gene alterations. The frequency of alterations was analyzed using a chi-square test with Yate's correction. RESULTS: Genes with frequent alterations included TP53 (59.8%), KRAS (54.8%), APC (27.7%), and CDKN2A (22.4%). Frequent genes with amplifications were MYC (6.7%), MDM2 (5.9%), GATA6 (5.5%), and CCND1 (3.4%). Patients younger than 40 years had significantly lower frequency of APC mutations than those 40 years and older (10.4% v 28.7%; P =.0008). Druggable genomic alterations were detected in 22.3% of patients: BRAF V600E (1.2%), BRCA1 (1.8%), BRCA2 (3.2%), ERBB2 amplification (3.2%), KRAS G12C (3.3%), NTRK1/2/3 fusion (0.07%), MSI-high (7.0%), and TMB-high (12.2%), with no significant differences in the frequency according to age (<40 years v ≥40 years; 22.1% v 22.3%). TMB of 10-20 Mut/Mb was observed in 4.8% of patients, and TMB ≥20 Mut/Mb was seen in 7.3% of the cohort. CONCLUSION: RWD from clinical panel testing revealed the genomic landscape in small intestine cancer by subgroup. These findings provide insights for the future development of treatments in advanced small intestine cancer. [ABSTRACT FROM AUTHOR]

PURPOSE: ERBB2 copy number (CN), measured using next-generation sequencing, is a predictive biomarker for trastuzumab efficacy in human epidermal growth factor receptor 2 (HER2)–positive advanced esophagogastric and gastric cancer (AGC). We aimed to investigate the association of ERBB2 amplification and gene coalterations with response and resistance to trastuzumab-combined chemotherapy. METHODS: The SCRUM-Japan GI-SCREEN was a comprehensive genomic profiling project of GI cancer tissues using Oncomine Cancer Research Panel and Oncomine Comprehensive Assay. From 885 patients with AGC who successfully underwent gene profiling, 74 with ERBB2 amplification (CN ≥ 4.0) and who received first-line trastuzumab-combined chemotherapy were selected, and ERBB2 CN and gene coalterations were assessed. RESULTS: ERBB2 CN did not differ in tumor response to trastuzumab-combined chemotherapy (one-way analysis of variance test, P =.37). Multivariate analysis using the Cox proportional hazard model revealed that ERBB2 CN (continuous log2-converted CN, hazard ratio, 0.76; 95% CI, 0.62 to 0.93; P <.01) and receptor/oncogene amplifications in the HER2 signaling pathway (hazard ratio, 2.5; 95% CI, 1.2 to 5.3; P =.01) were significant predictors for progression-free survival (PFS). ERBB2 variants coexisted in five patients (7%) and were missense mutations. Two patients with low variant allele frequencies (VAFs; 8%, 12%) showed high ERBB2 CN (55, 80) and durable response (≥ 20 months), whereas three patients with high VAFs (66%–90%) showed low ERBB2 CN (8-11) and no response with short PFS (1-10 months). CONCLUSION: ERBB2 CN and gene coamplification in the HER2 signaling pathway were positive and negative predictors of PFS in trastuzumab-treated HER2-positive AGC patients, respectively. HER2-positive AGC patients with a high VAF of ERBB2 showed poor outcomes and may need HER2 tyrosine kinase inhibitors and trastuzumab deruxtecan. ERBB2 CN and gene coamplification on the HER2 pathway in gastric cancer are predictors for trastuzumab response. [ABSTRACT FROM AUTHOR]