Hello, my name is Charlotte Teunissen, Professor of neurochemistry, and I will talk to a poster that I’m presenting at CTAD next week in San Diego. And the poster has a title “High diagnostic performance of the random-access Sysmex HISCL pTau217, Aβ42 and Aβ40 plasma assays for detecting amyloid pathology across the Alzheimer’s disease spectrum”. And in this poster, so as the title says, we validated novel assays that have been developed on the Sysmex HISCL instrument...
Hello, my name is Charlotte Teunissen, Professor of neurochemistry, and I will talk to a poster that I’m presenting at CTAD next week in San Diego. And the poster has a title “High diagnostic performance of the random-access Sysmex HISCL pTau217, Aβ42 and Aβ40 plasma assays for detecting amyloid pathology across the Alzheimer’s disease spectrum”. And in this poster, so as the title says, we validated novel assays that have been developed on the Sysmex HISCL instrument. And we exactly, precisely, we validated three assays, pTau217, one for Aβ42, and one for Aβ40. And we validated it analytically, so we evaluated sensitivity, specificity, the CV, intra-assay CV and inter-assay CV, lower limit of detection and parallelism and also recovery. And all analytical variables were very good in this assay. And in terms of precision, so intra-assay CV, the levels were very low. So they were on average below 5% for all of the assays, all three assays. For pTau217, in a very low range, we saw some increase in concentrations, but still below 20% and that’s very exceptional. And the higher levels are related to the low concentrations and that’s what you typically see in such assays for pTau217. So the performance was very good. And next we validated these assays in clinical patients so we compared this Hiscl pTau217 assay to the LumiPulse pTau217 assay. And we also compared the discriminatory value of the pTau217 ratio over Aβ42, both on the Hiscl and also on the LumiPulse assays. And for the discrimination of AD patients from controls. And let me check just shortly, because we included quite a lot of patients. Yeah, 100 controls and 180, 150 AD even. So also 50 MCI patients who were amyloid positive and 50 MCI who were amyloid negative and then 50 AD dementia. And so you should say I have to correct myself 100 MCI or AD who were amyloid positive and 50 MCI who were amyloid negative. And for the discrimination AD from control, as I already said, we looked at the discriminative value and the best performing assay was the Hiscl, either pTau217 alone or as a ratio to Aβ42 and areas on the curve were 0.93 and 0.94, so really high. LumiPulse also performed good, but slightly less. There we had the area under the curve 0.90 and 0.91. For Aβ42, we again observed that the best discriminative performance was obtained with the Hiscl assay for the Aβ42/40 ratio for discriminating AD from controls. Area under the curve was 0.80, so not as nice as for pTau217. For comparison with LumiPulse and Simoa, those areas under the curve were below 0.70 on average. So we also defined the cutoffs, also to discriminate between all those different clinical subgroups where we measured also Aβ42-positivity or negativity and using the Hiscl assay pTau217 ratio to Aβ42 an intermediate zone defined by the 90% specificity and sensitivity values and that led to a 12 percent, 12.1 percent to be precise, of patients that were in the intermediate zone. For comparison on Aβ42/40 ratio the discrimination was less good similar to cutoff approach but their high number of 39 patients fell into the intermediate or indiscriminate zone so for those we don’t have a very clear result. So this again talks to the high diagnostic value of pTau217 and the small intermediate zone of 12.1% is really promising and for use of this highly accurate assay for clinical practice.
This transcript is AI-generated. While we strive for accuracy, please verify this copy with the video.
