On Jul. 15, 2025, C2N Diagnostics (C2N), announces the launch of two new highly anticipated plasma assays for Research Use Only: C2N eMTBR-tau243 and C2N %p-tau MAA.

C2N eMTBR-tau243 (endogenous Microtubule Binding Region) is a unique blood test that selectively detects a specific region of tau; this fragment has been shown to closely track insoluble tau aggregates within neurofibrillary tangles in Alzheimer’s disease. C2N cites research that says this may provide the potential to improve the diagnostic evaluation of Alzheimer’s pathology in clinical trials, supporting essential disease staging, predicting disease progression and response to treatment, and monitoring treatment efficacy.

This new plasma assay builds on the existing C2N eMTBR-tau243 test in cerebrospinal fluid launched by C2N nearly two years ago and is available for Research Use Only. C2N obtained the exclusive rights for these technologies from the Bateman Lab at WashU Medicine. With funding from the GHR Foundation, the C2N team optimized and industrialized these assays using rigorous analytical methods to bring them to their current state. The company aims to integrate the new plasma C2N eMTBR-tau243 assay into clinical routine in the future.

 C2N is also launching a novel p-tau multi-analyte assay (MAA). This assay uses high-resolution mass spectrometry (LC-MS/MS) to precisely quantitate six analytes related to phosphorylated and nonphosphorylated forms of tau (%p-tau181, %p-tau205 and %p-tau217). The C2N %p-tau MAA measures multiple phosphorylated tau forms from a single sample and, therefore, enables greater efficiencies. This test is likewise available for Research Use Only.

 C2N’s LC-MS/MS methodologies enable a ratio of phosphorylated tau divided by non-phosphorylated tau (%p-tau) that previously has been shown to mitigate for confounding factors such as age and medical comorbidities like kidney disease. The Journal of the American Medical Association (JAMA) published a large clinical study that found C2N’s PrecivityAD2™ test accuracy was not impacted in the primary care arm of the study despite having patients of older age and with higher prevalence of comorbidities.  

The company believes the C2N %p-tau MAA and C2N eMTBR-tau243 assays will play a key role in biopharma clinical trials, enabling better assessment of Alzheimer’s disease pathology and supporting a precision medicine approach to novel treatment strategies. The assays will cover both early-stage and late-stage tau pathology identification, providing a robust marker for disease identification, staging, and stratification.

The Precivity™ line of blood tests currently available clinically to aid healthcare providers in the detection of amyloid plaques in the brain, a pathological hallmark of Alzheimer’s disease, and inform medical management and treatment decisions