Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio

The Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio is an in vitro diagnostic test that measures phosphorylated tau-217 and beta-amyloid 1-42 in blood plasma using chemiluminescent enzyme immunoassay (CLEIA) on the LUMIPULSE G1200 System. It is intended to aid healthcare providers in identifying adult patients aged 50+ with signs/symptoms of cognitive decline who have amyloid pathology associated with Alzheimer's disease, using predefined cutoffs to classify results as negative, indeterminate, or positive for amyloid pathology.

Both the proposed device and predicate (Lumipulse G β-Amyloid Ratio 1-42/1-40) are in vitro diagnostic ratio tests using automated CLEIA technology on the LUMIPULSE G1200 System with two-step sandwich immunoassays. The key difference is specimen type: the proposed device uses blood plasma (K₂EDTA), while the predicate uses cerebrospinal fluid (CSF). The proposed device measures different analytes (pTau217 and Aβ1-42) versus the predicate (Aβ1-42 and Aβ1-40), and uses different cutoff thresholds reflecting the different specimen matrices and target populations.

CLSI EP05-A3 (precision), CLSI EP06-Ed2 (linearity), CLSI EP07 and EP37 (interference testing), CLSI EP17-A2 (detection limits), CLSI EP34 (measuring interval), CLSI EP28-A3c (reference intervals), CLSI EP35 (specimen type equivalence), and CLSI EP39 (surrogate sample selection).

The proposed device is substantially equivalent to the predicate because both are Class II in vitro diagnostic ratio tests using identical CLEIA technology and the same instrument platform (LUMIPULSE G1200), with identical regulatory classification and product code structure. Although they differ in specimen type (plasma vs. CSF) and specific analytes measured, they serve the same clinical purpose—identifying amyloid pathology in cognitive decline patients—using comparable two-step immunoassay methodology. The clinical performance data from 499 patients showed strong agreement with amyloid PET/CSF reference standards (91.8% positive predictive value for positive results, 2.7% for negative results), demonstrating performance suitable for the intended use despite the different specimen and analyte combination.