An approach for improvement of the accuracy of cancer gene panel testing.

BACKGROUND: Tissue-based comprehensive genomic profiling (CGP) is increasingly being employed for genotype-directed therapies in patients with advanced cancer. However, tissue availability may limit their potential applications. In Japan, the cost of cancer gene panel tests is covered by public insurance for patients diagnosed with advanced solid tumors once in their lifetime. Therefore, it is essential to improve the success rate (reportability) and accuracy of CGP tests. The purpose of this study was to identify the factors associated with efficient and accurate CGP testing using relevant information obtained from real-world data. METHODS: This study included 159 samples analyzed using tumor-only panel FoundationOne® CDx cancer genome profiling (F1CDx) and 85 samples analyzed using matched-pair panel OncoGuide™ NCC Oncopanel system (NCCOP) at St. Marianna University Hospital. Sample characteristics (fixation conditions, storage period, histology, tumor cell ratio, and genomic tumor cell content), CGP performance, and quality control status were evaluated across all 244 tested samples. RESULTS: In 237/244 samples (97.1%), CGP testing results were successfully obtained [F1CDx, 99.4% (158/159) and NCCOP, 92.9% (79/85)]. An increased number of fibroblasts, inflammatory cells, and necrotic tumor cells, long-term storage, and/or prolonged fixation of tissue sections were involved in the unreported results and/or qualified CGP results. In addition, a negative correlation between median insert size values and ΔΔCq was observed in the NCCOP system. CONCLUSION: We identified various factors associated with efficient and accurate CGP testing using relevant information obtained from real-world data, suggesting that thorough selection and preparation of tissue sections could optimize CGP and maximize useful information.

Clinical Utility of Genomic Profiling Tests in Patients with Advanced Gastrointestinal Cancers.

BACKGROUND: Comprehensive analyses of cancer-related genomic alterations are expected to lead to increased availability of targeted therapies. However, in patients with gastrointestinal (GI) cancers, the utility of genomic profiling is unclear because of common non-druggable alterations and rapid disease progression that prevent a sufficient time period to seek targets. OBJECTIVE: The aim of this study was to determine the utility of genomic profiling tests in patients with GI cancers. METHODS: The subjects of this retrospective study were patients with GI cancers and patients with non-GI cancers who underwent tissue-based genomic profiling at a single institution from April 2017 to October 2020. The profile of gene alterations, frequency of tumor mutational burden-high (≥ 10 Muts/Mb), and accessibility of recommended molecular targeted therapy were compared between patients with GI cancers and patients with non-GI cancers. RESULTS: In all, 133 patients with GI cancers and 63 patients with non-GI cancers were included. The genomic profiles of GI cancers showed the highest frequencies of TP53, KRAS, and APC mutations and a significantly lower frequency of PIK3CA mutations than those of non-GI cancers. Tumor mutational burden-high was significantly less prevalent in GI cancers (4% vs 20%, p = 0.008). Twenty-nine patients with GI cancers (40%) and 35 patients with non-GI cancers (56%) were recommended for targeted therapies based on the findings. Among them, seven patients each with GI cancers and non-GI cancers received the recommended therapy on their genomic findings, which showed similar treatment accessibility between the GI and non-GI cancer groups (10% vs 11%, p = 0.791). HER2-targeted and BRAF-targeted therapies were the primary treatments administered to patients with GI cancers. CONCLUSIONS: Although their genomic profiles revealed fewer druggable sites, patients with GI cancers accessed targeted therapies similarly to patients with non-GI cancers. The utility of genomic profile testing in patients with GI cancers was highlighted to determine if patients can receive specific treatments, such as HER2-targeted and BRAF-targeted therapies.