Researchers from Hiroshima University have introduced a groundbreaking framework aimed at enhancing the identification of pathogenic variants among the numerous variants of uncertain significance (VUS) found in comprehensive genomic profiling (CGP) of cancers. This novel approach promises to refine the accuracy of precision oncology by enabling more effective prioritization of these VUS.
The Challenge of Comprehensive Genomic Profiling
Comprehensive genomic profiling has revolutionized cancer diagnostics by allowing for the detection of a wide array of genomic alterations across various cancer types. This method facilitates the use of genome-matched therapies, which can significantly improve patient outcomes. However, it has also led to a significant challenge: the increasing prevalence of VUS. These genetic alterations, whose clinical implications remain ambiguous, require careful interpretation and management within clinical settings. The preference for the term “variant” over “mutation” is intentional, aiming to avoid any preconceived notions of pathogenicity.
The Framework for Prioritization
The research team at Hiroshima University created a structured framework to identify candidate variants for further functional analysis, specifically focusing on the BRCA1 and BRCA2 genes. These genes are well-known for their association with Hereditary Breast and Ovarian Cancer (HBOC) due to the presence of pathogenic germline variants.
The findings of this study were published in the European Journal of Human Genetics on March 2, 2026. Since the introduction of CGP into clinical practice in Japan in 2019, more than 100,000 patients have undergone this testing, significantly advancing the integration of genomic data into cancer care.
Clinical Observations Driving Research
The impetus behind this research stemmed from a compelling clinical case. A patient exhibited an extraordinary response to platinum-based chemotherapy, despite a grim prognosis characterized by postoperative recurrence in multiple organs. This patient’s prolonged remission prompted further investigation into the underlying genetic factors contributing to their response.
Data Collection and Analysis
The research team gathered data from 2,172 CGP tests conducted across 13 institutions in the Chugoku-Shikoku region of Japan, between September 2019 and July 2025. Among the 526 variants detected in the BRCA1/2 genes, there were 130 known pathogenic variants and 396 classified as VUS, encompassing 153 unique variants. To assess the pathogenicity of these 153 VUS, the team employed ten in silico predictors—validated computational methods designed to evaluate the potential impact of genetic variants on protein function or RNA splicing.
Prioritization of Variants for Functional Investigation
The analysis led to the selection of ten VUS for further functional assessment. This group included eight missense variants, which alter a single amino acid within a protein, and two splicing variants that may disrupt normal RNA splicing and, consequently, protein function. While these variants had been documented in laboratory studies, their clinical significance remained unestablished.
The goal of the researchers was to systematically prioritize variants that warranted additional functional evaluations.
Focus on a Specific Variant
Among the prioritized variants, the team zeroed in on BRCA2:c.67 G>C, which had been identified in multiple CGP tests, including in the patient with the notable chemotherapy response. Functional analysis demonstrated that this variant disrupts the normal splicing of BRCA2, leading to the skipping of exon 2 and potential alteration of the reading frame. This discovery provides a plausible explanation for the patient’s remarkable reaction to treatment.
The findings, alongside a concurrent laboratory study, support the classification of BRCA2:c.67 G>C as a pathogenic heritable variant.
Future Directions and Applications
Looking ahead, the research team aims to explore whether this prioritization framework can be applied to variants identified in other hereditary cancer syndromes or inherited genetic disorders. Additionally, they are interested in integrating insights from in silico prediction tools into the routine interpretation of CGP results.
Key Takeaways
- Hiroshima University researchers developed a framework to prioritize variants of uncertain significance in cancer diagnostics.
- Comprehensive genomic profiling aids in detecting genetic alterations but presents challenges due to the prevalence of VUS.
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The study utilized data from 2,172 CGP tests, identifying 526 variants in BRCA1/2, with a focus on ten selected for functional evaluation.
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The variant BRCA2:c.67 G>C was linked to an exceptional patient response to chemotherapy, underscoring the importance of accurate variant classification.
In conclusion, this innovative framework has the potential to significantly enhance the landscape of genomic diagnostics in oncology. By effectively prioritizing VUS, it paves the way for more personalized and effective cancer treatment strategies, ultimately improving patient care in the era of precision medicine.
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