ABtest-MS is a new option within ABtest Service based on mass spectrometry that allows the simultaneous determination of Aβ1-40 and Aβ1-42 from just 250 microliters of plasma.
ABtest-MS does not require enzymatic digestion or prior immuno-precipitation of samples, substantially shortening the turnaround time and reducing costs compared to other similar assays.
Because of its robustness to interference from other plasma components, particularly anti-Aβ antibody, and to variations in pre-analytical sample handling, ABtest-MS may be particularly suitable to assist in the recruitment and follow-up of patients in connection with clinical trials or in a patient care setting.
Unlike other similar assays, ABtest-MS does not require prior immuno-precipitation of the sample with anti-Aβ antibodies making it particularly suitable for quantifying amyloid peptides in plasma in the framework of clinical trials of immunotherapies or other anti-β-amyloid treatments.
ABtest-MS has already been tested in several clinical trials with which we have collaborated (BioFINDER, BioFINDER 2, DPUK-Korea). The results will be published very soon confirming its usefulness to determine the Aβ42/Aβ40 ratio in plasma with the ability to predict brain amyloid status and predict the course of the disease.

Determination of the Aβ42/Aβ40 ratio by ABtest-MS in a subgroup of 74 MCI patient samples from the phase II trial of ABvac40 (active anti-Aβ40 vaccine).

The Aβ42/Aβ40 ratio in plasma differs significantly between amyloid-PET positive and negative individuals (P <0.0001).

The Aβ42/Aβ40 ratio in plasma discriminates positive and negative amyloid-PET with high accuracy (AUC = 0.872; 0.881 for the model adjusted for APoE genotype) and balanced sensitivity (80.4%) and specificity (94.4%) values.