Newsletter · · Ashutosh Agarwal

Two Alzheimer's Blood Tests Clear the FDA as a Reimbursement Cloud Forms - The Neuro & Alzheimer's Pipeline - Week of September 6, 2026

The Neuro & Alzheimer's Pipeline for the week of August 31 to September 6, 2026. Podcast synthesis on C2N's and Roche's Alzheimer's blood tests clearing the FDA, the Mayo Clinic Laboratories CEO flagging a 2027 Medicare lab-pricing cut, and a credentialed neurologist mounting a Cochrane-backed attack on anti-amyloid drug efficacy.

The Neuro & Alzheimer's Pipeline

Week of September 6, 2026: Two Alzheimer's Blood Tests Clear the FDA as a Reimbursement Cloud Forms

Last week the big Alzheimer's news was a scan: a brain-imaging company won approval for a tau dye and promptly sold itself. This week the story moved from the scanner to something far cheaper and far more scalable, the blood test. In the last seven days, two separate podcasts, one hosted by the man who actually sells these tests to hospitals, confirmed that a pair of blood tests for Alzheimer's have now cleared the U.S. Food and Drug Administration (the FDA, the agency that decides what doctors are allowed to use). And in the same week, one of the field's most prominent skeptics came out with a new book and the hardest attack yet on the drugs those tests are meant to feed patients into.

A quick honesty note on sourcing, because this newsletter lives or dies on it. This was, once again, a thin week for dedicated biotech-industry podcasts: none of the trade-press shows (Endpoints, BioCentury, STAT, Business of Biotech) surfaced Alzheimer's coverage in the window at all. But the four episodes we did get are unusually substantive, and two of them come from an actual operator, the CEO of Mayo Clinic Laboratories, rather than a pundit guessing from the outside. That is a genuine upgrade in signal quality over recent weeks.

(Quick vocabulary, used throughout. Amyloid and tau are the two toxic proteins that build up in an Alzheimer's brain. Today's approved drugs, Eli Lilly's Kisunla and Eisai/Biogen's Leqembi, try to clear amyloid. ARIA is the brain-swelling-and-bleeding side effect those drugs can cause. p-tau-217 is a specific fragment of the tau protein that shows up in the blood and tracks closely with amyloid buildup, and it has become the single most useful thing to measure in a blood sample. A blood-based biomarker is simply a signal you can read from an ordinary blood draw instead of a spinal tap or a brain scan: cheaper, easier, and far more scalable. PPV/NPV, positive and negative predictive value, are just "when the test says yes, how often is it right?" and "when it says no, how often is it right?" PAMA is a 2014 U.S. law that sets how much Medicare pays for lab tests; it matters here because looming payment cuts could squeeze the very labs running these new tests.)

TL;DR

  • Two Alzheimer's blood tests are now FDA-cleared, and one operator says the diagnostic bottleneck is finally cracking. The CEO of Mayo Clinic Laboratories confirmed that C2N Diagnostics' blood test just won FDA clearance and is being offered through Mayo; a separate neurology news podcast reported that Roche's Elecsys p-tau-217 blood test was cleared by the FDA on August 24. Both aim to replace expensive brain scans and spinal taps with a simple blood draw, the missing piece the whole anti-amyloid business has needed to find patients at scale.
  • But there is a reimbursement cloud right behind the sunshine. The same Mayo Labs CEO warned that looming Medicare lab-pricing cuts (under a law called PAMA) could hit the fee schedule in 2027 and make it "very difficult" for labs to keep offering this level of service, a direct headwind for every diagnostics name in the space.
  • The amyloid bear got louder, and better armed. Neurologist and bestselling author Dr. David Perlmutter, promoting a new book, cited a Cochrane review of 17 trials (~20,000 patients) finding the anti-amyloid drugs' benefit "trivial" while more than 20% of patients get brain bleeding or swelling. His blunt verdict: "The risk is high. The benefit is zero, virtually."

What's new

The headline: two Alzheimer's blood tests are now FDA-cleared, and the man selling one of them says the diagnostic logjam is breaking. On Becker's Healthcare Podcast ("The Future of Diagnostics, AI and Precision Medicine," Sep 1), an operator/insider segment featuring Dr. William Morice II, CEO of Mayo Clinic Laboratories, Morice singled out Alzheimer's as the area drawing the most notice right now, "where there's advancing therapies, there's advancing understanding, and there's advancing diagnostics." The concrete news: Mayo is now offering C2N Diagnostics' blood test, which "just got FDA cleared," alongside Mayo's own Alzheimer's tests. Why it moves numbers: for two years the bear case on the whole anti-amyloid franchise has rested on a bottleneck, you couldn't confirm who actually had amyloid without a PET scan or a spinal tap, so patients never got diagnosed fast enough to be treated. A cleared, scalable blood test is exactly the tool that unclogs that pipe. An operator putting it into real clinical use is a stronger signal than any analyst's forecast.

The detail on the C2N test, and it is a good one. On Answers from the Lab ("Unlock the Full Potential of Research Data," Sep 3), another operator/insider segment with Morice and Mayo's Dr. Bobbi Pritt, Morice explained what C2N actually does. The company is "spun out of Washington University," and it uses mass spectrometry (a lab technique that weighs molecules very precisely) to measure "proteins in the blood and ratios of protein in the blood that are associated with amyloid deposition in the brain." The performance number is the one to write down: the test "has greater than 90% positive predictive value and negative predictive value," and works "even in patients down to the age of 40 with symptoms of cognitive decline." Morice named C2N's CEO (Dr. Joel Braunstein) and Mayo collaborators including the well-known Alzheimer's researcher Dr. Ronald Petersen. He also let slip a telling aside about the drug side of the story, recalling that the first wave of interest came "like five, six years ago when... the Biogen drug, which didn't really take off," a quiet reminder that the diagnostics have, so far, outrun the drugs' commercial success.

The operator's framing of the week: a blood test that is right more than 90% of the time, in patients as young as 40, now available through Mayo Clinic Laboratories. The tools to find Alzheimer's patients are arriving faster than the drugs to treat them.

The second clearance: Roche's p-tau-217 blood test. On NeurologyLive® Mind Moments® ("Dual Therapy and the Changing Treatment Landscape of SMA," Sep 4), the episode itself is mostly about a different disease (spinal muscular atrophy), but its "Neurology News Minute" segment carried the fact that matters to us: "on August 24th, the FDA cleared Roche's [Elecsys] p-tau-217, a blood test that uses a single biomarker to both rule in and rule out amyloid pathology in adults 55 years and older... being evaluated for Alzheimer's disease." Roche describes it as "the first and only FDA-cleared single-biomarker blood test that supports both rule-in and rule-out assessment of amyloid pathology using the same validated cutoffs across primary and specialty care." Why it matters: "rule in and rule out" using one marker and the same cutoffs in a regular doctor's office (not just a specialist clinic) is the holy grail for primary care, it is how you screen millions of people cheaply. Two cleared blood tests in one newsletter, from two different companies, is the clearest sign yet that the diagnostic layer is maturing fast.

The reimbursement headwind hiding behind the good news. Back on Becker's, Morice, who also chairs the board of the American Clinical Laboratory Association, the labs' trade group, named the biggest headwind for the whole diagnostics industry: PAMA, the law governing how Medicare prices lab tests. Labs "just got done with our last round of data collection," and if the law stands, "we'll be facing likely a round of cuts that will be coming for the fee schedule in 2027, which would be very difficult for us... to really honestly maintain the level of service" against falling reimbursement. A remedy bill (the "Results Act") has been introduced, and he said "everyone... in the diagnostic space" is watching it. Why it matters: the same week the FDA blesses two new Alzheimer's blood tests, the person running one of the country's biggest reference labs is flagging that Medicare may pay labs less starting in 2027. Great new tests do not help much if the economics of running them are getting squeezed.

Meanwhile, the amyloid skeptics found a sharper knife. On Health Longevity Secrets ("The Alzheimer's Lie: It's Not The Amyloid," Sep 1), a pundit, but a credentialed one, Dr. David Perlmutter, a board-certified neurologist and six-time bestselling author, promoting his new book Brain Defenders, with host Dr. Robert Lufkin, the argument was that the field has been "fighting the wrong enemy." Perlmutter's headline claim: Alzheimer's isn't primarily caused by amyloid buildup at all, but by the brain's own immune cells (called microglia) flipping from a protective mode into a destructive one when the body's metabolism goes bad. On the drugs specifically, he was scathing and, importantly, specific. He pointed to "a Cochrane analysis from several months ago that reviewed 17 studies... [encompassing] 20,342 individuals," roughly 18 months long, and said the drugs' effect on slowing decline was, in the reviewers' own word, "trivial." Meanwhile, he said, "more than 20% of individuals taking these drugs will develop either bleeding and/or swelling into the brain... and in fact some people have died getting these drugs." His verdict: "The risk is high. The benefit is zero, virtually." He argued the drugs were approved "not because of their clinical effectiveness... but [because] the drug manufacturers were able to convince the FDA that... beta-amyloid is the cause of Alzheimer's disease, and this drug lowers beta-amyloid." Why it matters: none of this is investable news, but it is the most concrete version of the bear case this newsletter has captured, and it lands in the same week two companies just bet real money that finding amyloid faster is worth it.

The debate

Does cheap, FDA-cleared blood testing plus broader coverage finally turn anti-amyloid into a genuine multi-billion-dollar franchise, or do modest drug benefit, brain-bleed risk, and now a reimbursement squeeze keep uptake structurally weak while the "it's not amyloid" camp gains ground?

Bull: The single biggest bottleneck is cracking in real time. Two Alzheimer's blood tests cleared the FDA in one fortnight, C2N's mass-spec test (>90% predictive value, now live through Mayo) and Roche's p-tau-217 (cleared to both rule in and rule out, in primary and specialty care). Blood beats scans and spinal taps on cost, speed, and scale, which means far more patients can be identified and, if the amyloid thesis holds, funneled toward Kisunla and Leqembi. When the CEO of Mayo Clinic Laboratories is the one telling you the diagnostics are maturing and being adopted, that is an operator signal, not a pundit's hope. The tools to find the patients are finally here.

Bear: Look at what actually happened. Two diagnostics got cleared, not a single new sales number for an amyloid drug. Once again this week produced zero Kisunla launch color, zero Leqembi ramp, zero coverage decision. Morice himself, unprompted, recalled that "the Biogen drug... didn't really take off." And a credentialed neurologist just cited a 20,000-patient Cochrane review calling the drugs' benefit "trivial" against a >20% rate of brain bleeding or swelling. A perfect test that finds amyloid faster does not help if clearing that amyloid barely moves the patient, you have just built a very efficient funnel into a disappointing drug. Layer on the PAMA reimbursement cuts threatened for 2027, and even the diagnostics economics face a headwind.

Net: For the second week running, the hard, dollar-relevant events in this space are in the plumbing, first tau imaging (last week), now blood diagnostics (this week), not in the drugs. The diagnostic layer is clearly maturing faster than the commercial drug story it is meant to serve. The referees that decide how big this franchise gets, actual Kisunla and Leqembi sales prints, a clean Medicare path, and hard evidence that clearing amyloid changes lives, are all still ahead. And a lab-pricing cut in 2027 now sits on the risk list too.

Stocks in play

No drugmaker reported Alzheimer's commercial data on a podcast this week. Every real corporate development was in diagnostics. Flagged for what it is.

  • Roche (RHHBY / ROG SW), the week's cleanest public read. Bull: its Elecsys p-tau-217 blood test is now FDA-cleared as "the first and only" single-biomarker blood test to both rule in and rule out amyloid across primary and specialty care (NeurologyLive), a genuine land-grab in primary-care Alzheimer's screening, on top of Roche's own drug pipeline. Bear: a diagnostic test is a modest revenue line for a company Roche's size, and the whole complex faces the PAMA pricing risk. Next catalyst: real-world ordering volumes and any payer-coverage decisions for blood-based AD testing.
  • C2N Diagnostics, private, but the name to know. Bull: FDA-cleared, mass-spec blood test with >90% positive and negative predictive value, working in patients as young as 40, now distributed through Mayo Clinic Laboratories (Answers from the Lab). Bear: not investable in public markets, and it competes directly with Roche, Fujirebio, and every reference lab building its own assay. Next catalyst: commercial uptake and any strategic/financing news. A WashU spinout with a cleared, high-accuracy test is exactly the kind of asset a larger diagnostics player might one day covet.
  • Mayo Clinic Laboratories (private, part of Mayo Clinic), the distributor and the operator's voice. Bull: positioning itself as the trusted "platform" that bundles its own tests with partners' like C2N; strong volume and revenue growth this year per its CEO (Becker's). Bear: directly exposed to the 2027 PAMA fee-schedule cuts it is warning about. Next catalyst: the fate of the "Results Act" reimbursement-fix bill.
  • LLY (Eli Lilly), read-through / absent again. Bull: cheaper, scalable blood diagnostics should, in theory, widen the funnel of diagnosed patients eligible for Kisunla. Bear: Kisunla went unmentioned in the podcasts for yet another week, no launch metrics, no infusion color, and a prominent neurologist just called the whole anti-amyloid class's benefit "trivial." Next catalyst: actual Kisunla patient-start or sales data (none, again, this week).
  • BIIB (Biogen) / Eisai, read-through / absent, with a small sting. Bull: same funnel logic, more diagnosed patients could help the Leqembi ramp. Bear: Mayo's CEO offhandedly noted "the Biogen drug... didn't really take off" (Answers from the Lab), a reference to the earlier Aduhelm era, but not the endorsement bulls want to hear. Next catalyst: Leqembi/IQLIK sub-Q ramp numbers (none this week).
  • No coverage this week (flagged, not fabricated): Roche pipeline drugs (trontinemab, gantenerumab successors, bepranemab/UCB); ABBV (AbbVie) neuroscience, emraclidine, Vyalev, Cerevel assets; named tau/non-amyloid drug programs, E2814, remternetug, diranersin/BIIB080, ACI-35, TREM2, complement therapeutics; QTRX (Quanterix), Fujirebio, LH (LabCorp), DGX (Quest) by name; LNTH (Lantheus) and GEHC (GE HealthCare) follow-up on last week's tau-imaging deal; OPCH (Option Care Health) and infusion/specialty pharmacy; BMY (Bristol Myers Squibb) Cobenfy and the muscarinic/psychiatry story; Parkinson's and Huntington's; and any specific CMS coverage decision. None appeared in this week's podcasts.

Read-throughs

  • Blood diagnostics (QTRX/Quanterix, C2N, Roche Elecsys, LH/LabCorp, DGX/Quest): this was the week's center of gravity. Two FDA clearances (C2N and Roche p-tau-217) plus an operator confirming real clinical adoption (Becker's; Answers from the Lab; NeurologyLive). The investable read: the blood-test market is real and moving from "will doctors order it?" to "which platform wins?" Quanterix wasn't named this week, but it competes in exactly this p-tau-217 lane and rides the same adoption wave, and the same PAMA risk.
  • Lab reimbursement (a new read-through for the whole complex): the PAMA fee-schedule cuts threatened for 2027 (Becker's) are a genuine, dated risk for every name that runs Medicare-reimbursed lab tests, LabCorp, Quest, Quanterix, and the reference labs. Watch the "Results Act."
  • PET imaging (LNTH, GEHC): quiet this week after last week's Curium/Lantheus deal and the tau-scan approval. The read-through, though, is competitive: if a $20-ish blood draw with >90% accuracy can rule amyloid in or out, the economic case for a pricey PET scan narrows to confirmation and trial-selection roles. Blood is the volume play; scans become the specialist tool.
  • Anti-amyloid drugs (LLY Kisunla, BIIB/Eisai Leqembi): the diagnostic funnel is widening, but the drugs themselves got no fresh commercial data and a fresh, well-sourced attack on their efficacy (Health Longevity Secrets). Better patient-finding only pays off if the drugs deliver, still the open question.
  • Non-amyloid mechanisms (microglia, metabolism): Perlmutter's microglia thesis (Health Longevity Secrets) is years from anything investable, but it keeps the "wrong target" narrative alive and points where the next generation of drug bets (immune-modulating, mitochondrial) may eventually go.

What changed vs last week

Last week was an imaging week, a tau scan approval and an $8 billion acquisition of Lantheus by Curium. This week the diagnostics story jumped a layer, from the scanner to the blood test: two FDA clearances (C2N and Roche Elecsys p-tau-217) and an operator confirming real adoption (Becker's; Answers from the Lab; NeurologyLive). That is a meaningful upgrade in relevance: last week's tau scan is a specialist tool; a blood test is a mass-market one.

A new item on the risk list: the PAMA lab-pricing cut threatened for 2027 (Becker's) is the first concrete reimbursement headwind this newsletter has logged for the diagnostics complex. Worth tracking against the "Results Act" fix.

The bear case sharpened, and stayed consistent. Last week the "wrong target" argument came from the pathobiome/amyloid-as-antimicrobial angle. This week Perlmutter extended the same thesis from a different direction, microglia and metabolism, and, crucially, backed it with harder numbers: a 20,342-patient Cochrane review calling the drugs' benefit "trivial" and a >20% rate of brain bleeding/swelling (Health Longevity Secrets). Two weeks running, the skeptics have brought the more specific evidence.

What we did not get: any Kisunla launch metrics or infusion-capacity color, nothing; any Leqembi/IQLIK sub-Q ramp or international numbers, nothing; any Roche drug pipeline update (trontinemab, gantenerumab successors, bepranemab/UCB), nothing; anything on AbbVie's neuroscience assets, nothing; any tau-drug program news (E2814, remternetug, diranersin/BIIB080, ACI-35), nothing; a hard CMS coverage decision on the drugs, nothing; the muscarinic/psychiatry story (BMY Cobenfy), nothing; Parkinson's and Huntington's, nothing; infusion/specialty pharmacy (OPCH), nothing; any follow-up on last week's Lantheus/Curium tau-imaging deal, nothing. It was a blood-diagnostics-and-reimbursement week, with no fresh drug-sales or clinical-trial facts.