Implementation of a comprehensive genomic profiling (CGP) panel for precision oncology at a cancer center in Brazil.
Authors: Brianese Rafael Canfield Brianese , Santiago Karina , Miguez Ana Carolina Kerekes , Osorio Cynthia Bueno de Toledo , De Brot Marina , Andrade Louise De Brot , Torrezan Giovana Tardin , Loureiro Livia Oliveira , Carraro Dirce Maria 
Published: June 2024

e23520

Background: Assessing molecular alterations in solid tumors is essential for providing the best care in precision oncology. CGP tests utilize next-generation sequencing (NGS) to detect clinically relevant alterations and molecular signatures that are increasingly utilized in cancer careand can be performed in-house, which decreases test turnaround time (TAT) and costs. A paucity of studies have documented the experience of in-house testing at academic centers in Brazil. Methods: The TruSight Oncology (TSO) 500 assay/TSO 500 HRD are research use only (RUO) CGP assays that were validated for the detection of small variants (SVs), copy number variants (CNVs), microsatellite instability (MSI), tumor mutation burden (TMB) and genomic instability score (GIS) in DNA and gene fusions/splice variants in RNA in the NextSeq 500 system. Secondary analysis was performed with Illumina Connected Analytics. Tertiary analysis was performed with Illumina Connected Insights (ICI) and Sophia DDM. TMB ≥ 10mut/Mb was defined as TMB-High and GIS ≥ 42 was homologous recombination deficient (HRD). Results: We performed CGP on 40 FFPE samples (16 with HRD) with variable quality and block age most of which had known alterations detected by other genomics/molecular tests: 17 TNBC (16 paired DNA and RNA, 1 DNA only), 18 lung cancer (13 paired DNA and RNA, 5 DNA only), 1 endometrium cancer (DNA only, POLE mutated, 4 replicates), 1 colorectal cancer (DNA only, MSI unstable) and 11 sarcomas (RNA only). 84%, 84%, 90% and 89% of samples with DNA integrity number (DIN) > 2.5 were qualified for analysis of SVs/TMB, MSI, CNVs, and GIS, respectively, while for samples with DIN < 2.5 these values felt to 47%, 74%, 68% and 43%, respectively. RNA isolated from blocks dated up to 5 y.o. were qualified in 90% of cases while from older blocks only 6%. The 4 replicate (single sample) analysis showed 82% and 83% overall variant concordance in the ICI and Sophia DDM software, respectively. All previously known oncogenic alterations (SVs ≥5% VAF, fusions/splice, MSI, TMB) were detected (qualified samples) and with similar performance in ICI and Sophia, respectively: concordance 0.91/p < 0.0001 vs 0.94/p < 0.0001; sensitivity 100% vs 100%; specificity 98% vs 100%. TMB had 100% concordance with previous TMB results. Of note, 73% (8/11) TNBC samples analyzed for GIS were HRD and 75% (6/8) explained by BRCA1 germline mutation (25%) and BRCA1or RAD51C somatic promoter methylation (75%). Conclusions: This study demonstrates the utility of CGP and HRD testing in identifying multiple molecular alterations in FFPE tissue samples with high sensitivity and specificity. Pre-analytical variables directly impact data generation. BRCA1/RAD51C promoter methylation showed to be a potential biomarker for selecting metastatic TNBC patients for PARP inhibitor therapies. Offering CGP can potentially bring precision oncology to more patients with cancer in Brazil.