Multimodal molecular profiling of invasive ductal carcinoma: High concordance of qPCR with FISH in HER2 assessment and exomic landscape of high-risk subtypes.
Summary
This study evaluates the efficacy of qPCR for HER2 status assessment in invasive ductal carcinoma of the breast, comparing it with IHC and FISH. Results demonstrate high concordance between qPCR and FISH, particularly in resolving equivocal IHC 2+ cases. Furthermore, exploratory genomic profiling via WES on high-risk subtypes (HER2 3+ and TNBC) revealed somatic mutations in key genes such as TP53, BRCA1, and MYCN, as well as AR expression in TNBC. These findings highlight qPCR's potential as an accurate diagnostic tool and provide a foundation for future precision oncology strategies.
Analysis
Clinique: This study establishes qPCR as a robust and accurate diagnostic tool for HER2 status in invasive ductal carcinoma of the breast, showing 96.4% sensitivity and a kappa of 0.94 compared to FISH. Its immediate clinical impact lies in effectively resolving equivocal IHC 2+ cases (identifying definitive HER2 amplification in 41.3% of these cases), which can alter targeted therapeutic management. The identification of AR expression within the TNBC subtype suggests the presence of the clinically actionable Luminal Androgen Receptor (LAR) subtype, justifying clinical trials evaluating anti-androgen therapies. The time to clinical impact for qPCR is 1-3 years, as it could be rapidly integrated into existing diagnostic algorithms. Biomol: The primary discovery is the high diagnostic concordance of qPCR with FISH for HER2 gene amplification, validating qPCR as a reliable method. The technologies employed include IHC, FISH, qPCR, and whole-exome sequencing (WES). qPCR demonstrated excellent analytical validity (96.4% sensitivity) for HER2 amplification diagnosis. Exploratory WES, though on a small subset, identified pathogenic variants in TP53, BRCA1, and MYCN in TNBCs, and in PAK1, CUL3, and TP53 in HER2 3+ cancers. These findings of mutations in key genes provide leads for novel predictive or prognostic biomarkers and could justify the development of targeted sequencing panels for these aggressive subtypes, with implications for early-phase clinical trials testing therapies targeting these alterations.