New therapies are being developed for breast cancer and in this process some "old" biomarkers are re-utilized and given a new purpose. It is not always recognized that, by changing a biomarker's intended use, a new biomarker assay is created. The Ki-67 biomarker is typically assessed by immunohistochemistry (IHC) to provide a proliferative index in breast cancer. Canadian laboratories assessed the analytical performance and diagnostic accuracy of their Ki-67 IHC laboratory developed tests (LDTs), of relevance for the LDTs' clinical utility. Canadian clinical IHC laboratories enrolled in the Canadian Biomarker Quality Assurance (CBQA) Pilot Run for Ki-67 in breast cancer by invitation. The Dako Ki-67 IHC pharmDx assay was employed as a study reference assay. The Dako central laboratory (USA) was the reference laboratory. Participants received unstained slides of breast cancer tissue microarrays (TMAs) with 32 cases and performed their in-house Ki-67 assay. The results were assessed using QuPath, an open-source software for bio-image analysis. Positive percent agreement (PPA, sensitivity) and negative percent agreement (NPA, specificity) were calculated against the Dako Ki-67 IHC pharmDx assay for 5%, 10%, 20% and 30% cut-offs. Overall, PPA and NPA varied depending on the selected cut-off; participants were more successful with 5% and 10%, than with 20% and 30% cut-offs. Only four out of 16 laboratories had robust IHC protocols with acceptable PPA for all cut-offs. The lowest PPA for the 5% cut-off was 85%, for 10% was 63%, for 20% was 14%, and for 30% was 13%. The lowest NPA for the 5% cut-off was 50%, for 10% was 33%, for 20% was 50%, and for 30% was 57%. Despite many years of international efforts to standardize IHC testing for Ki-67 in breast cancer, our results indicate that Canadian clinical LDTs have a wide analytical sensitivity range and poor agreement for 20% and 30% cut-offs. The poor agreement was not due to the readout, but rather due to IHC protocol conditions. IKWG recommendations related to Ki-67 IHC standardization cannot take full effect without reliable fit-for-purpose reference materials that are required for the initial assay calibration, assay performance monitoring, and proficiency testing.

Huntington’s disease (HD) is a devastating neurodegenerative disease that results in motor, cognitive, and psychiatric impairments. HD results from an autosomal dominant polyglutamine expansion in the huntingtin (HTT) gene that results in a misfolded and aggregated protein. The disease is uniformly fatal and demonstrates characteristic neuropathological changes. While the striatum is preferentially affected, the cortex and many other brain regions are involved in pathogenesis and show progressive changes throughout the disease.

Background and Clinical Significance: DNA methylation profiling has revolutionized the classification of central nervous system (CNS) tumors, providing insights into tumor prognosis, recurrence, and personalized treatments. However, a significant challenge remains in classifying rare or molecularly undefined high-grade gliomas (HGGs) that fail to match existing methylation reference classes. This study evaluates the clinical, histopathological, and molecular characteristics of three unclassifiable cases through a retrospective analysis. Methylation profiling was performed by the National Institute of Health based on the 11b6 and 12b6 of the Heidelberg classifier, as well as the National Cancer Institute/Bethesda classifier. The cases were evaluated for histopathological features, molecular markers, and clinical outcomes. Case Presentation: We present three adult patients with histologically confirmed HGGs that were unclassifiable by standard DNA methylation profiling. All patients presented with diverse clinical and radiographic findings. Histopathological examination confirmed high-grade glial neoplasms in each case. However, methylation profiling failed to yield clear matches for any known class. Instead, profiling suggested indeterminate IDH-wildtype neoplasms with aggressive clinical courses. Following treatment, one patient experienced disease progression and died, while the other two remained without evidence of recurrence at follow-up. Conclusions: These cases underscore the persistent diagnostic challenges posed by CNS tumors that are unclassifiable by current DNA methylation, highlighting the urgent need for expanded reference datasets. While methylation profiling has transformed the field of tumor diagnostics, its limitations still exist. Enhanced collaboration to broaden diagnostic categories is essential to broaden diagnostic classifiers. Until these tools are refined, integration of clinical, histological, and molecular findings is imperative to optimize patient management, improve classification accuracy, and optimize therapeutic outcomes. Unclassifiable HGGs represent a critical gap in CNS tumor diagnostics. Addressing this requires global collaboration to enrich methylation databases. In the interim, a multimodal diagnostic strategy remains essential for the management of these challenging tumors.

Recently, more attention has been paid to identifying biomarkers for epilepsy to direct a more personalized treatment strategy, especially for patients who suffer from drug-resistant epilepsy which carries a much poorer prognosis. microRNA has emerged as an important and diverse type of biomarker that can participate in metabolic and cellular processes of the disease and, importantly, can be detected in patient’s serum. In this short review, we compile state-of-the-art evidence regarding miRNA-146a, a novel biomarker that shows high potential for studying epileptogenesis, monitoring disease progression, evaluating treatment response, and may even function as a therapeutic target given its role in the process of neuroinflammation.

Open access peer-reviewed chapter