Clinical Insights
Central Lab for CNS Clinical Trials:
7 Criteria That Actually Predict Data Quality
Choosing a central lab for CNS clinical trials now turns on two questions most selection checklists never ask: whether the lab runs your full primary and secondary fluid biomarker menu today, and whether its operations keep that data comparable across regions and timepoints. The generic guidance stops at “scientific expertise and quality systems.” It never names a biomarker, a platform, or a single pre-analytical requirement. That vagueness is where programs get hurt. It is also important to confirm each assay’s regulatory status and intended use – whether it will support a diagnostic decision, inclusion/exclusion criterion, patient stratification, or exploratory endpoint.
CNS studies lose data in two specific places, and both are avoidable.
The fluid biomarker menu has expanded well past the core amyloid and tau panel into NfL, GFAP, sTREM2, synuclein, and multiple pTau isoforms, and a lab that lists “biomarker assays” as a category tells you nothing about which markers are actually live. The second failure mode is operational, and it is worse. Pre-analytical handling differences alone can swing CSF Aβ42 by more than 50%, which means your result can be wrong before the assay ever runs.
The seven criteria below are ordered by how hard they are to replicate. The first three separate a defensible lab from a risky one. We have written each so you can hand it straight to a vendor as a direct question.
1. Does the Lab Run Your Full CNS Fluid-Biomarker Menu Today, Not Just the Core AD Panel?
Ask for the menu analyte by analyte, because “we do neuro biomarkers” is where the risk hides. A central lab for CNS trials should run your full primary and secondary menu today, not on a roadmap, and the marker most sponsors want most, plasma GFAP, is often exactly the one still sitting at research-use-only across the industry.
Map each marker to what it actually indexes before you map it to your protocol. NfL is a non-specific marker of axonal and neuronal injury, elevated across many neurodegenerative and neurological conditions rather than any single disease. GFAP indexes astrocytic activation and neuroinflammation.
Plasma pTau217 is the more Alzheimer’s-specific signal, tracking amyloid and tau pathology. sTREM2 reflects microglial activation, with genuine diagnostic signal but directionally inconsistent findings across disease stages. A 2026 autopsy-correlation study (Kivisäkk and colleagues, in Neurology) made the same point: antemortem plasma pTau217 tracked amyloid plaque and tau tangle burden at autopsy, while GFAP and NfL reflected broader brain stress rather than one disease.
MLM’s menu covers this expanded panel: amyloid (Aβ40, Aβ42, Aβ42/40 ratio), tau variants (pTau181, pTau217, pTau231, total tau, brain-derived tau), NfL, GFAP, neuroinflammation markers (sTREM2, IL-6, TNF-α, IL-1β, CRP, CCL2), synuclein (alpha- and beta-synuclein), and synaptic markers (Neurogranin, SNAP-25, NPTX2, VAMP2), all listed on MLM’s CNS and neurodegenerative biomarker menu.
Get this wrong and it is expensive. A menu you assumed was live but is actually roadmap forces a mid-study lab add or a second vendor, and the moment you split an analyte across two labs you inherit the cross-site variance the rest of this checklist works to remove. So ask which markers run in-house today, on which matrix, and at what regulatory status. Do not accept “neuro biomarkers” as an answer.
Regulatory status should be confirmed analyte by analyte and against the assay’s intended use. An assay appropriate for exploratory use is not automatically appropriate for a diagnostic or enrollment decision, so the regulatory and validation status needs to be matched to the role that biomarker will play in the trial. For GFAP specifically, regulatory status differs by matrix: MLM offers plasma GFAP as LDT / IVDR, while CSF GFAP remains RUO.
| Biomarker | Matrix | What it indexes | Typical trial use |
| Aβ42/40 ratio | CSF, plasma | Amyloid plaque pathology | Inclusion/exclusion, target engagement |
| pTau217 | Plasma | Tau pathology tied to amyloid | AD-specific screening and staging |
| pTau181 / total tau | CSF, plasma | Neuronal injury and tau pathology | Diagnosis support, monitoring |
| NfL | Plasma, CSF | Axonal/neuronal injury (non-specific) | Safety and neurodegeneration monitoring |
| GFAP | Plasma, CSF | Astrocytic activation, neuroinflammation | Clinical-trial decisions and exploratory use |
| sTREM2 | CSF | Microglial activation | Exploratory neuroinflammation PD marker |
| Alpha-synuclein | CSF | Synucleinopathy pathology | PD and DLB stratification, exploratory |
| Neurogranin / SNAP-25 | CSF | Synaptic integrity and loss | Exploratory synaptic PD marker |
2. Which Analytical Platform, and Will They Keep You on It for the Life of the Study?
Pick the platform deliberately, then get the lab to commit to it in writing for the full study, because CNS biomarker values are platform-dependent and do not transfer, even when platforms correlate strongly. Two assays can correlate at r=0.89 and still be non-interchangeable. That single fact quietly breaks longitudinal endpoints.
A 2024 head-to-head comparison of plasma Alzheimer’s biomarkers found high correlation but a lack of concordance between platforms: Aβ42 correlated at r=0.794 and pTau181 at r=0.891, yet the Aβ42/40 ratio reached only r=0.572, and one platform read Aβ42 on average 16.157 pg/mL higher than the other in Bland-Altman analysis. A separate serum NfL comparison found one platform reading roughly 24% higher than another, with both judged equally suitable for longitudinal monitoring only when the same platform is used throughout.
Platform choice also sets your usable sensitivity floor. In subpicomolar detection comparisons, multiplex ECL methods could detect but not reliably quantify concentrations that digital immunoassays measured with the lowest imprecision, so a low-abundance marker that reads cleanly on one platform can sit below the reliable quantification range on another. That makes this criterion two questions, not one: which platform, and a documented commitment to keep you on it.
Any protocol amendment, lab transfer, or multi-region pooling that crosses platforms needs a cross-validation or bridging study budgeted up front. Correlation is not interchangeability. Cross-platform mismatches are a recurring source of pain when sponsors try to pool or compare data across sites and regions, and you pay for that pain in dollars and in timeline.
MLM names Lumipulse (including the FDA-cleared Lumipulse G pTau217/Aβ42 plasma ratio), cobas/Elecsys, MSD S-PLEX, and ELISA immunoassays as its deployed platforms.
| Platform | Method | Sensitivity note | Interchangeable? |
| Lumipulse | CLEIA | FDA-cleared pTau217/Aβ42 plasma ratio | No |
| MSD S-PLEX | ECL multiplex | Detects but under-quantifies at subpicomolar range | No |
| cobas/Elecsys | Automated immunoassay | Established automated CSF AD assays | No |
3. Is their Pre-Analytical SOP Actually Built for Fragile Neuro-Biomarkers?
Ask to review the lab’s written CNS pre-analytical requirements before study start, because for neurological blood-based biomarkers, sample handling can influence the result before the assay ever runs.
The 2025 Global Biomarker Standardization Consortium (GBSC) consensus provides an evidence-based framework for handling blood samples intended for neurological biomarker measurement. The recommendations reinforce that pre-analytical standardization should begin at the collection site, not when the sample reaches the central laboratory.
For plasma biomarker testing, key considerations include:
- Collect blood in an EDTA tube
- Centrifuge within the defined processing window
- Aliquot plasma into screw-capped, low-binding polypropylene tubes
- Store frozen samples at −80°C
- Control pre-centrifugation delays, freeze-thaw cycles, temperature excursions, and hemolysis
Example workflow for neurological blood-based biomarkers based on the evidence-based GBSC consensus sample handling protocol.
Adapted from: Verberk IMW, et al. Alzheimer’s & Dementia. 2025;21:e70752.
The tube requirement is particularly important for amyloid biomarkers. Low-binding polypropylene helps minimize protein adsorption to tube surfaces, making the choice of collection and aliquot materials part of the analytical strategy, not simply a logistics detail.
CSF requires its own matrix-specific handling procedures. Published recommendations similarly emphasize appropriate tube material and standardized collection and processing to minimize pre-analytical variability, particularly for amyloid biomarkers.
The practical question for a Sponsor is therefore not simply, “Can the lab run the assay?” It is: “Can the central lab define the pre-analytical requirements, translate them into site-level instructions and collection materials, and maintain that process consistently across every site in the study?”
That is where pre-analytical control becomes a central-lab selection criterion rather than simply a laboratory SOP.
4. Can They Run Your US and EU Patients Under One Accredited Roof?
Confirm one company can run both your US and EU patients under a single, currently accredited roof, because split labs reintroduce exactly the cross-site variance a central lab is meant to remove. The bridging study you pay for when US and EU sit in separate labs is avoidable. You just have to select for it.
A single accredited lab means one method, one reference range, and one data system across regions, which ties directly to criterion 7. Split labs mean method bias and two separate reference intervals layered onto your endpoint before analysis even begins.
MLM’s accreditation detail is specific and checkable, which is the point. The Mönchengladbach, Germany lab holds CLIA accreditation (2025, valid to 2027), CAP (2024 to 2026), DIN EN ISO 15189, a GLP compliance statement, and is one of eight NGSP Level 1 certified labs in Europe. The Memphis, Tennessee lab holds a CLIA Certificate of Compliance (2025) and CAP (2025 to 2027). Being CAP and CLIA accredited as well as ISO 15189 is what lets US and EU samples run in one place, under the oversight of a single partner rather than fragmented regional vendors.
MLM’s established laboratory network, science-led service model and operational agility are now strengthened by Labcorp’s global scale, scientific breadth and operational infrastructure. The combined organization has a wholly owned laboratory network across North America, Europe, Asia and Africa, expanding its ability to support complex multinational clinical trials with consistent scientific, operational and regulatory oversight.
5. Can They Validate a Biomarker for Your Exact Context of Use, Including One With No FDA Clearance or CE-IVD Yet?
Ask what validation tier the lab will build for your specific context of use, because a biomarker does not need full diagnostic clearance to be usable in a trial, but its validation must match its intended use. An accreditation logo tells you almost nothing about whether the assay is defensible for your decision.
The framework comes from EU IVDR (Article 5(5)) and FDA-NIH BEST. Context of use defines the biomarker category plus its intended application, and fit-for-purpose means validation sufficient for that defined use, built on the V3 triad of verification, analytical validation, and clinical validation. A biomarker can fail in the clinic not because of weak scientific rationale but from poor assay choice and thin validation. The tier for an exploratory pharmacodynamic marker is not the tier for an inclusion/exclusion gate, so ask for the specific tier and the context-of-use documentation.
This is where a lab’s regulatory standing stops being a slogan and becomes one concrete proof point. In Europe, MLM can develop and validate in-house tests within the EU IVDR Health Institution framework. In the United States, MLM’s CLIA-certified laboratory can develop and analytically validate laboratory-developed tests (LDTs). This gives MLM the ability to support biomarkers for which an appropriate CE-IVD or FDA-cleared assay may not yet be available. MLM documents this as an IVDR and LDT validation capability.
The important distinction is intended use. Regulatory status and validation requirements are not interchangeable across exploratory, pharmacodynamic, screening, inclusion/exclusion, and diagnostic applications. The assay’s validation strategy therefore needs to be matched to the specific decision it will support in the trial.
6. Global Logistics, Cold Chain, and Chain of Custody at Every Site
Score the lab on cold chain, kit control, and chain of custody at every site, because criterion 3’s pre-analytical rules only hold if the sample survives transit from the site to the freezer. Ask for one thing: the chain-of-custody and temperature-monitoring record from your hardest-to-reach site.
Lab teams are often the overlooked stakeholders in multinational trials, and biomarker data that sits in separate lab systems delays safety reviews and interim analyses. For fragile neuro markers with a sub-2-hour ideal time-to-freezer, courier and customs reliability from emerging-market sites is a data-integrity variable, not a shipping detail.
MLM’s logistics stack is specific: audit-trail tracking, scalable biostorage, 24-hour temperature monitoring, kits built in the proprietary MLM Kit Manager with pre-labeled barcoded tubes shipped in the MLM Safeguard Box from Memphis or Mönchengladbach, and encrypted, 21 CFR Part 11 compliant data transfer through the mlm online portal, detailed on MLM’s sample management and logistics page. The footprint now includes wholly-owned Cytespace Africa Laboratories in the City of Tshwane, South Africa, described as the only fully CAP-accredited central lab in South Africa, which recently tripled its molecular throughput with Roche cobas 5800 systems and extends reliable cold chain into Sub-Saharan Africa.
One operational number, read precisely. Cytespace Africa Laboratories publishes a TAT Safety Testing KPI of 96.5% under 24 hours and 99% under 48 hours, plus 1% or fewer missed kit shipments per month and a cancelled-test rate at or below 1%. That is a Cytespace Africa Laboratories safety-lab metric, not a CNS-biomarker turnaround guarantee.
MLM’s global study support, strengthened by Labcorp’s broad international laboratory organization, brings greater scale and operational infrastructure to complex multinational trials while preserving the agility, scientific focus and high-touch service model that define MLM’s approach.
7. Turnaround Time and Central Versus Local Testing for Longitudinal Endpoints
Treat turnaround time and the central-versus-local choice as one decision, because when a CNS biomarker gates enrollment, TAT is a recruitment cost, and when it is a longitudinal endpoint, only a single central lab keeps the numbers comparable. The 30-versus-14-day screening gap a gating assay quietly adds is real, and it lands on your timeline.
Turnaround gates enrollment. Trials requiring a mandatory fresh biomarker or biopsy test had a median screening duration of 30 days versus 14 days without one, and centralized testing ensures standardization but carries longer turnaround that can stretch timelines. One case study predicted a screen-fail rate above 80% on an expensive gating assay until optimized screening let non-randomizing patients learn within minutes instead of waiting on lab TAT.
Central beats local for comparability. Central labs use one method, one reference range, and one data system, whereas local reference-interval differences can cause more than 30% variability in normal-versus-abnormal classification. That variance lands directly on a longitudinal CNS endpoint, where a shift in classification between visits can read as a treatment effect that is really an artifact of which lab ran the sample. It is preventable, but only if one lab runs the marker for the whole study.
Central testing is preferred when data consistency and comparability matter, such as multicountry and biomarker-driven trials. This compounds criterion 2: one platform and one lab for the life of the endpoint.
The honest limit is this: no central lab in this space, MLM included, publishes a CNS-biomarker-specific TAT guarantee. The only public proxy is the Cytespace Africa Laboratories safety-lab KPI from criterion 6. So make CNS-assay TAT a direct question to the lab, and weight central-lab comparability over raw speed for any longitudinal marker.
Frequently Asked Questions
Can one central lab run both my US and EU trial patients under a single accredited roof?
Yes in MLM’s model. Wholly-owned, separately accredited labs in Germany (CAP 2024 to 2026, CLIA valid to 2027, ISO 15189) and Memphis (CAP 2025 to 2027, CLIA 2025) operate under one company, with the wholly-owned Cytespace Africa Laboratories in the City of Tshwane, South Africa extending the footprint across the US, Europe, and Africa under a single partner.
MLM’s global footprint is further strengthened by Labcorp’s wholly owned laboratory network spanning North America, Europe, Asia and Africa.
Do biomarker values from one platform transfer to another if I switch labs or platforms mid-study?
No. Head-to-head studies consistently show strong correlation but poor concordance, including plasma Alzheimer’s markers across two platforms and serum NfL reading roughly 24% higher on one platform than another. Stay on one platform and one lab for a longitudinal endpoint, and budget a cross-validation bridging study up front if a platform or lab change is genuinely unavoidable.
How do I run a biomarker with no FDA clearance or CE-IVD yet, like plasma GFAP or sTREM2?
Use a fit-for-purpose, context-of-use approach: match the validation strategy to the biomarker’s intended role rather than waiting for full diagnostic clearance. In Europe, MLM can develop and validate in-house tests within the EU IVDR (Article 5(5)) Health Institution framework. In the United States, MLM’s CLIA-certified laboratory can develop and analytically validate LDTs. Ask for the assay’s specific regulatory status, validation approach, and intended-use documentation—not just an accreditation logo.
What turnaround time should I expect when a CNS biomarker gates enrollment?
No central lab, MLM included, publishes a CNS-specific TAT guarantee. The closest public proxy is Cytespace Africa Laboratories’ safety-testing KPI of 96.5% under 24 hours and 99% under 48 hours, which is a safety-lab figure, not a CNS one. Ask directly, since a mandatory gating assay pushes median screening from 14 to 30 days and drives screen-fail cost.
Does MLM offer newer markers like sTREM2 or alpha-synuclein, or just the standard AD panel?
MLM’s CNS and neurodegenerative page lists sTREM2 and both alpha- and beta-synuclein among its offered analytes, alongside NfL, GFAP, and the pTau isoforms.
If you are scoping a central lab for CNS clinical trials and want to pressure-test your fluid-biomarker menu against your protocol, let’s start that conversation. Every one of these seven criteria is really one question about your program’s risk, and it is cheaper to answer before a bridging study lands on the invoice.
MLM Medical Labs has built its CNS approach around scientific depth, direct access to specialists and the operational agility to respond when a study changes. Those strengths remain distinctly MLM – and are now strengthened by Labcorp’s broader global reach, scientific capabilities and operational infrastructure.
For sponsors, that creates a more powerful proposition: specialized CNS expertise and high-touch execution, supported by the scale of a much larger global laboratory organization.
You shouldn’t have to choose between expertise, agility and scale. Demand all three.
Begin with MLM’s CNS and neurodegenerative biomarker services, then bring us your hardest analyte.