Blood-based pre-screening in the SKYLINE secondary prevention Ph3 gantenerumab study

SKYLINE was a secondary prevention study that used blood-based biomarker (BBBM) pre-screening to screen out participants with a low likelihood of amyloid positivity by positron emission tomography (PET) or cerebrospinal fluid (CSF) testing.

This retrospective analysis used data from SKYLINE (ClinicalTrials.gov: NCT05256134; terminated prematurely) and the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) study to compare predicted and actual clinical performance characteristics of various biomarker combinations using prototype Elecsys^® plasma immunoassays (Roche Diagnostics International Ltd, Rotkreuz, Switzerland).

In >3500 participants screened in SKYLINE, tau phosphorylated at threonine 181 (pTau181) and apolipoprotein E4 protein (ApoE4p) was the highest-performing BBBM combination. Actual clinical performance of the BBBM pre-screening in SKYLINE was similar to predictions based on A4 in terms of screen-out rate, positive predictive value, and 1-negative predictive value.

BBBM pre-screening in SKYLINE using prototype plasma pTau181 and ApoE4p immunoassays effectively alleviated participant burden by avoiding unnecessary PET or CSF testing.

We compared blood-based biomarker (BBBM) performance in SKYLINE and Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4). Pre-screening improved amyloid positivity (defined by positron emission tomography/cerebrospinal fluid) screen failure rate. Tau phosphorylated at threonine 181 (pTau181) and apolipoprotein E4 protein was the highest-performing combination among BBBMs tested. Pre-screening eased participant burden by reducing subsequent screening procedures.