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Publication
Scientific Reports

Evaluation of serum as an alternative matrix to plasma for NULISA‑based proteomic blood biomarker measurements

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  • April 18, 2026
Topic/Product:
CNS, Neurology
Disease Area:
Alzheimer's Disease
Sample Type:
Plasma, Serum

Abstract

The NULISAseq CNS Disease Panel has high potential for AD diagnosis, but the comparability of serum vs. plasma remains unclear. We compared its performance on 43 matched serum-plasma pairs from a memory clinic cohort. The panel reproducibly quantified 124 targets (mean CV = 4.9%) with high detectability (mean = 95.7%). Serum-plasma correlations were strong (ρ > 0.7) for 79 targets. 48 targets had significant NULISA Protein Quantification (NPQ) differences, with 32 higher in plasma. Plasma had more erythrocyte-enriched proteins (HBA1, PGK1, SOD1, PRDX6), while serum had more platelet-derived proteins (CD40LG, BDNF, VEGFA, Aβ40). For classical AD biomarkers, serum-plasma correlations were stronger for p-tau, GFAP, and NfL (ρ > 0.9) than for Aβ targets (ρ = 0.594–0.785). Tau levels were higher in plasma; GFAP and NfL were similar, and Aβ peptides were mixed. Twelve targets, along with p-tau217/Aβ42, were linked to AD diagnosis, with plasma generally showing stronger effects. Our results support serum use but suggest plasma performs better for AD using this panel.

Authors:

  • Marissa F. Farinas, 
  • Yijun Chen, 
  • Xuemei Zeng, 
  • Michel N. Nafash, 
  • Ann D. Cohen, 
  • Oscar L. Lopez & 
  • Thomas K. Karikari

    Authors and Affiliations

    1. Department of Psychiatry, School of Medicine, University of Pittsburgh, 3811 O’Hara Street, Pittsburgh, PA, 15213, USA

      Marissa F. Farinas, Xuemei Zeng, Michel N. Nafash, Ann D. Cohen, Oscar L. Lopez & Thomas K. Karikari

    2. Biofluid Biomarker Laboratory, Western Psychiatric Hospital, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213, USA

      Marissa F. Farinas, Xuemei Zeng, Michel N. Nafash & Thomas K. Karikari

    3. Alzheimer’s Disease Research Center, University of Pittsburgh, Pittsburgh, PA, 15213, USA

      Marissa F. Farinas, Xuemei Zeng, Michel N. Nafash, Ann D. Cohen, Oscar L. Lopez & Thomas K. Karikari

    4. Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15213, USA

      Yijun Chen

    5. Department of Neurology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA

      Oscar L. Lopez

    6. UPMC Western Psychiatric Hospital, 3811 O’Hara Street, Pittsburgh, PA, 15213, USA

      Thomas K. Karikari

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Steve Williams, MD, PhD

CSO

Dr. Willams serves as the company’s Chief Scientific Officer. He was previously Chief Medical Officer at Standard Biotools and at SomaLogic where he pioneered the discipline for discovery and validation of predictive, diagnostic and prognostic models using machine-learning applied to large-plex proteomics. 20 such tests were used for drug characterization, safety and efficacy when incorporated in clinical drug trials at Pharma/Biotech and 17 different multivariate tests were validated and translated into regulated healthcare uses. Prior to SomaLogic, Dr. Williams was at Pfizer in the UK and the USA as a clinical triallist in Translational Medicine, and subsequently as VP, Global Clinical Technology. He sat on the National Advisory Council for the National Institute of Biomedical Imaging and Bioengineering, the Executive Committee for the FNIH Biomarkers Consortium, and worked with FDA and PhRMA on developing evidentiary standards for biomarker qualification. Dr. William’s medical training was in London, at Charing Cross and Westminster Medical School, followed by a PhD in medicine/physiology at the same institution and training in Radiology at the University of Newcastle Upon Tyne. Steve is co-inventor on 26 proteomics patents and author/coauthor on multiple foundational proteomics manuscripts.

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Justin McAnear

CFO

Mr. McAnear serves as the company’s Chief Financial Officer. He brings over 25 years of operational and financial leadership experience across various sectors and was instrumental in taking 10x Genomics public in 2019, serving as its CFO for over five years. Mr. McAnear served for over 3 years as Tesla’s VP of Worldwide Finance and Operations, supporting landmark initiatives such as the Model X and Model 3 launches and Solar City acquisition.  He also held various roles at Apple and J&J earlier in his career and served as a naval officer and aviator for over 9 years.