# After Amyloid, Alzheimer's Patients Ask What Comes Next - The Neuro & Alzheimer's Pipeline - Week of October 4, 2026

> The Neuro & Alzheimer's Pipeline for the week of October 4, 2026, covering September 27 to October 4, 2026. A podcast synthesis on what comes after amyloid-clearing drugs like Leqembi and Kisunla: treatment persistence, blood tests replacing follow-up PET scans, ARIA monitoring, the first clinical tau PET scans, and early tau biology.

## The Neuro & Alzheimer's Pipeline

### Week of October 4, 2026: After Amyloid, Alzheimer's Patients Ask What Comes Next

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Three weeks ago the story here was **tau**. Two weeks ago it was **cholesterol**. Last week it was the **blood test's instruction manual**. This week the most useful podcast moment came from a patient, not a doctor or a CEO.

On Being Patient's Brain Talk, a 60-year-old man described finishing 18 months of Leqembi, turning down the maintenance dose, and using a blood test to confirm his amyloid was gone. Then he hit a wall: with his amyloid cleared, he no longer qualifies for most clinical trials. "There are a bunch of us who are coming through these disease modifying drugs with really good amyloid levels," he said. "So the question is, what do we do next?"

That one sentence holds three investment questions. How long do patients actually stay on these drugs? Do blood tests replace follow-up brain scans? And who is building the drugs for after amyloid is gone?

**A note on sources.** None of the drug companies (Lilly, Biogen, Eisai, Roche, AbbVie) spoke on any of them. None came from the dedicated biotech business shows. Most are medical-education sessions or academic interviews. Two are from practitioners who sell their own products, and we treat them with caution. One more thing to know: **both Keeping Current education sessions were funded by an "independent educational grant" from Eli Lilly**, which the sessions themselves disclose. That doesn't make them wrong, but you should know who paid for them.

**(Quick vocabulary, used throughout. Amyloid and tau are the two toxic proteins that build up in an Alzheimer's brain. The two approved drugs, Eisai/Biogen's Leqembi and Eli Lilly's Kisunla, are antibodies that clear amyloid. ARIA is their main side effect: brain swelling (ARIA-E) or tiny brain bleeds (ARIA-H) seen on an MRI scan. p-tau-217 is a piece of the tau protein that can be measured in an ordinary blood sample and acts as a stand-in for a brain scan. A PET scan uses a small radioactive tracer to show amyloid or tau in the brain directly. CSF is the spinal fluid collected with a lumbar puncture. Maintenance dosing means continuing the drug at a lower frequency after the initial course.)**

## TL;DR

* **The "after amyloid" patient is real, and has a persistence problem for drug makers.** A Leqembi patient on [Brain Talk | Being Patient](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjiyImkYceMLurwElA53SlY7GsbU2NKLFkkoC4xGhgXZrVq50i9tfIxmq347zexsatHEEodhuUa2uhotuK11IMkRmPCsKQOpiI4Ko2-2BBvwQ-2Fw-3D-3DrNHg_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNmaru5R5ZnA7k-2B5mEyqofKkEfp1FIke-2FSgr32hT5v0aRHqRHf83hFUfXdTnI-2BKBIUry9o9VEp0GPLitLfLO-2Bs5zITwUEBDjOjItSE7MIv1XeULEPphoOmjAFKF99k-2FYhKA-3D-3D) stopped after 39 infusions and declined maintenance. His reason: Lilly's guidance that Kisunla patients can stop once amyloid clears. His insurer wouldn't pay for a follow-up PET scan, so a p-tau-217 blood test told him he was clear. If patients take one company's stop-dosing logic and apply it to the whole drug class, the length of treatment, and the revenue per patient, gets shorter.
* **Brain scanning is a growing bottleneck, not a dying business.** Nuclear-medicine doctors on the [SNMMI Podcast Series](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOh-2Bhu4WQsRT5dTuFWxwGc19Rc1HTFFBCei4hzKlhruEd7oTXbX8WmsjC6TuIrNmA8T4Z2dq89V-2FR0nwFsm4TKUpCzCQmGH3UV1n3I-2BHQgtKqg-3D-3DMubj_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNlEoyjChcu-2BZqAPQf879zJ0YHuUsfgCzZSnpYBKBAqmhM5gB1zRhhdjIw756rcPPIAmGoy13hsdpWo1aMTy170W1llnM8JFRRb3ZpjyajaEJWCKj0adQHMPrOqPmZBl6zg-3D-3D) said amyloid PET is now "fairly high-volume." Clinical tau PET is just starting: two major academic centers are doing "their first clinical tau scan either last week or next week." And there are "not enough nuclear medicine physicians, period." A Lilly-funded radiology session on [Keeping Current CME](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjqKLpm1GOLfL6DzQkJxlyZ4-2BeZlkRq4g4kTT6kOWJ4xU0Eu7PpNNvntqKsCpL34Kn-2F7ZCrkZvS8ki6k1DYxSW5jnr-2FinMkJgf-2F8w874sJJJA-3D-3DKcRt_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNn4dbTb6IPA3dqZT1qpd3hylVgkzts11wWkCmbyznzP0TjvBbohjcSbRP-2BRq2urYGD6upPGW014eM7KNNOLUqFeZ8yQPu8c6Ry-2BIu0f-2FQdt8NitW9LUmVq90jl2FgkuMeQ-3D-3D) said patients giving themselves at-home injections **still need scheduled safety MRIs**.
* **Tau keeps building, but only in the science.** A new Cell paper on [This Week in Neuroscience](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjA-2BgnruZxoZXINE-2B26tBYzV-2BFLWO8VXl4m5HtiWysMuNdJHPbqldbWo-2FXNpssAOPaL0cXp9t4M6HPSh-2F2xDS3NcCX18lfomMwKI1tE43IxxQ-3D-3DNpCh_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNmk3p3ViQvlqzM8YKJMX80JRw222IlydsTPCIGfSinxvpCGGEVDW67-2BlLHWwOIP2fqd-2BTaAPIpyvm-2Bnu-2FQByH4npQ84yMn0pfpdtX0HIP8MGge5NB0-2BL8aaW5NcMKivE6g-3D-3D) found a memory protein called Arc that packs toxic tau into tiny bubbles that carry it between brain cells. The author of **The Vanishing Family** said on [Causes or Cures](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjGbuMT7ot-2BdvBHbmH5wH9VoQLekNv2vtxlPh8jfSQ0AN1PLhCqwdYOsIDyqcwiiSQuf-2Fe1Tk3goWd8shk2l3vgiT9Jw8M16AnVq0-2BgKnWWEA-3D-3DhjdO_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNk5aTCUrP30S5pyhyK2EhCaqSO3AzEG8rNFRnq-2BlEBRWhGwnnInuC0LCyjMj290OYTmdL7hGpuXPEUZ8v2FDCCGlyOqZgwSh5CzDsVVYq-2FAd-2BC-2F7rFiU9ekFdV3Num1jGQ-3D-3D) that "something like seven different pharma companies" are developing drugs that lower tau. Neither podcast named a program or gave a trial result.

## What's new

### 1. A patient's exit interview: 39 infusions, no maintenance, no follow-up scan

**PATIENT (not an operator or analyst).** On [Brain Talk | Being Patient](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjiyImkYceMLurwElA53SlY7GsbU2NKLFkkoC4xGhgXZrVq50i9tfIxmq347zexsatHEEodhuUa2uhotuK11IMkRmPCsKQOpiI4Ko2-2BBvwQ-2Fw-3D-3DsJJW_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNqn3R9GS02H4i3Oaxfr46ouxp-2BGJPYD-2FCdYO8dDmsTu8o-2BLLAeye4HBHX7N2oVPDF0rAq0r4hS2pm5COV6MVUfmw8wL-2FyC-2BH-2BF58eX-2BEPTeMHYy72pqmSEkk8EHJPdNG5g-3D-3D) ("Four Years to Get a Memory Test: An Early-Onset Alzheimer's Diagnosis at 60 | Sean Terwilliger," Sep 29), Sean Terwilliger described his full journey on Leqembi. It is one person's story, so read it as a vivid example, not data. But almost every step touches something investors model.

**The diagnosis was abrupt.** His first neurologist told him, roughly, "the prognosis is eight to 10 years from diagnosis. Come back in two weeks and I'll have started the process of getting you onto the infusions. Have a good rest of your day." He wanted the drug immediately: "get me on the drug, get me into the hospital, get that stuff pumping through me." He was offered a genetic test (APOE4, the gene that raises the risk of ARIA) and turned it down: "I didn't want to know I wanted the drug. I didn't want to wait a second."

**He completed the course, then stopped.** "I did 18 months of Lakembi… two infusions a month… 39 infusions." He was offered the lower-frequency maintenance dose and declined, partly to try trials of tau or inflammation drugs, "some of which you can't do when you're taking" Leqembi.

**Here is the important part: he used a rival's playbook.** His new neurologist pointed him to Lilly's Kisunla data, "where they showed that the maintenance dose on their drug wasn't even really necessary." His reasoning: "because the two drugs, while different, do functionally the same thing… can I take the guidance from Lilly and apply it to Lakembi… and go off the drug after my 18 months." His neurologist agreed.

**The scan he wanted was not covered, so a blood test filled the gap.** He wanted a follow-up PET scan to "hold two slides up… to a light and see the change." His prescribing neurologist "didn't think it was valuable," and "I also couldn't get insurance to pay for it." Instead he took a p-tau-217 blood test, which "showed that I do not show Alzheimer's pathology any longer." **(Our note, not from the podcast: from his description, which mentions p-tau-217 and an amyloid 42/40 ratio together, this sounds like a combined test such as C2N's PrecivityAD2. He did not name the brand.)** He plans to repeat the blood test "twice a year at, at minimum."

**And then he fell into a gap in the pipeline.** "I don't have enough amyloid. I don't have enough inflammation… I can't get into any clinical trials right now." He calls it "what I consider remission, cause we haven't cured the disease."

"There are a bunch of us who are coming through these disease modifying drugs with really good amyloid levels. So the question is, what do we do next?" That was Sean Terwilliger on Brain Talk | Being Patient.

**Why it moves numbers:** there are three threads here.

* **Treatment length.** Biogen and Eisai's revenue model leans on keeping patients on maintenance dosing, which is part of the pitch for the IQLIK at-home injection. If patients and neurologists start applying Lilly's "stop when clear" approach to Leqembi, years on therapy per patient fall.
* **Monitoring is moving to blood.** A repeat PET scan that an insurer won't cover is being replaced by a blood test. That's good for the lab-test companies and a mild negative for repeat PET volume.
* **A new patient group with no drug yet.** A growing pool of people who are amyloid-cleared but still have the disease is exactly who a tau or "post-amyloid" drug would treat. Right now, he says, the trials don't have a slot for them.

### 2. Self-injecting at home doesn't remove the MRI schedule

**EXPERT/CLINICAL (Lilly-funded education session).** On [Keeping Current CME](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjqKLpm1GOLfL6DzQkJxlyZ4-2BeZlkRq4g4kTT6kOWJ4xU0Eu7PpNNvntqKsCpL34Kn-2F7ZCrkZvS8ki6k1DYxSW5jnr-2FinMkJgf-2F8w874sJJJA-3D-3DsFlY_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNmd4gPPfErwNGbVVFjRxsYt-2BVQzpNcpP26ToUswkSYJ1F8w0WozkauyII9MbQaAMiPw8hD2OlVrLM6laN5OXH8JpEt7kNeFxNxQnLvvgZ2Mf2CyML-2B2VppET2-2Fra8DGlWw-3D-3D) ("Aligning on Amyloid-Targeting Therapy Imaging Protocols: A US Radiologist's Playbook," Sep 28), three academic specialists ran through how radiologists should support these drugs: **Tammy Benzinger** (Washington University School of Medicine), **Christopher Chen** (National University of Singapore) and **Tiago Gil Oliveira** (University of Minho, Portugal). The session discloses support from "an independent educational grant from Lili [Lilly]."

**The most investable exchange came near the end.** Benzinger asked whether patients now getting "these drugs available for self-administration at home" still need scheduled MRI monitoring. Chen: "My understanding is, yes, the MRI schedule is followed. And we need to be very, very careful about how we distribute the drugs, because you can't give people medications that they will give themselves before the report comes back." His bottom line: "you must have the MRI scan report and understand it before you give the next dose."

**On ARIA, the tone was reassuring but strict.** "Approximately 80 to 90% of ARIA is asymptomatic," Oliveira said, and "most of the time on treatment, the radiological findings are mild or moderate. And it's not often that you have to take action." But ARIA "usually occurs in the first six months," so scans are more frequent early and around any dose increase. Risk rises with the APOE4 gene, blood thinners and existing blood-vessel disease. Radiologists must now **count** microbleeds rather than say "a few": 4 or fewer is mild, 5 to 9 moderate, 10 or more severe. The good news for capacity: the core MRI protocol is "a 10- or 15-minute protocol" on "most of our scanners, including older models."

**Amyloid PET's role was stated plainly.** It is "our gold standard," and is "now used to determine eligibility for the approved amyloid targeting treatments," because "many patients with typical clinical picture of Alzheimer's dementia may not have amyloid." The panel also listed "the repeat amyloid PET scan, which needs to have both a visual read as well as quantification" as part of judging response to therapy. Compare that with the Being Patient story above, where the insurer wouldn't pay for exactly that scan.

**Why it moves numbers:** at-home injections were supposed to ease the infusion-chair bottleneck. This session says the **MRI bottleneck stays**, and adds a new logistics problem: making sure the drug doesn't reach a patient's fridge before the safety report is read. That matters for how fast IQLIK and any future at-home Kisunla can grow, and it supports steady MRI demand (GE HealthCare makes MRI scanners as well as PET tracers).
### 3. PET doctors say demand is outrunning readers, and tau PET is just starting

**EXPERT/CLINICAL, sponsored by GE HealthCare.** On the [SNMMI Podcast Series](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOh-2Bhu4WQsRT5dTuFWxwGc19Rc1HTFFBCei4hzKlhruEd7oTXbX8WmsjC6TuIrNmA8T4Z2dq89V-2FR0nwFsm4TKUpCzCQmGH3UV1n3I-2BHQgtKqg-3D-3DT-mU_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNtG19G93z7UE5IX3hY6iyf89cc49AW3XvMGJyBxKa90e9aNjlO-2BH9qFApPKSHgldGOfcsZJiO2adGsPqbG4g4BAw-2BhftN8kZn2tLtRgOHz-2FiJxe2fUubJJCVGCuxFS9nZA-3D-3D) ("How Long is Your Reading List? Brain Imaging in High-Volume Clinics," Sep 30), two nuclear-medicine physicians at academic and tertiary-care centers spoke. One is a neurologist by training; neither is fully named in the transcript we reviewed. The episode carries an advertisement for GE HealthCare's **Vizamyl** amyloid PET tracer.

**Why demand changed.** "Up until 2024, really for the last 120 years… this has been a clinical syndrome and a clinical diagnosis." The 2024 shift to defining Alzheimer's by biology (a positive amyloid test) "has driven a renewed interest in a lot of these PET images." Amyloid PET is now "a fairly high-volume practice because nowadays it's answering the question, does this patient have Alzheimer's disease?"

**Tau PET is at the very start of its curve.** "I'm aware of at least two major academic institutions that have told me they're doing their first clinical tau scan either last week or next week. And I bet that's just the tip of the iceberg across the country." Under the official guidelines for appropriate use, tau PET's distinct job is **prognosis**: showing how far tau has spread, which predicts how fast a patient will decline. "That is a piece of information we really don't have another way to get." The older FDG brain scan (which measures sugar use) is holding on: "I don't believe that our internal FDG practice has been diminished by the advent of tau imaging."

**The bottleneck is people.** "I would love to be reading amyloid PET and tau PET all day, every day. But even if I did, it would be the tip of the iceberg." And: "I don't think there are enough nuclear medicine physicians, period, to meet all this demand." The fix will be "a collaborative effort between nuclear medicine, neuroradiology, and others."

**Reports are getting more detailed.** "If you're getting into this for the first time in 2026, you not only need to be providing that visual read, but you need to be providing a Centiloid value." (A **Centiloid** is a standard 0-to-100 score for how much amyloid is present, comparable across tracers.) That's what lets doctors track how well a drug is clearing amyloid over time. One technical snag: the official FDA reading instructions for tau tracers don't always match what clinicians want to know, so a reader who follows the package insert exactly "could be doing it right, but still not providing the clinicians with the information they want." **(Our note: the two tau tracers they discussed are flortaucipir, Lilly/Avid's Tauvid, and one transcribed as "fluorquinolactone," which we believe is florquinitau (MK-6240), the tau tracer Lantheus owns.)**

They also cited Alzheimer's Association figures: **about 7.4 million Americans over 65** live with Alzheimer's (1.9 million aged 65–74, 2.9 million aged 75–84, 2.6 million over 85).

**Why it moves numbers:** this is the clearest picture we've had of PET demand from the people reading the scans. Amyloid PET volume is high, tau PET is just opening, and the binding limit is trained readers. That backs a volume story for tracer makers (Lantheus, GE HealthCare, Lilly's Avid), plus reading software and AI-assisted reads, more than a scanner story.

### 4. Europe's version of the blood-test playbook is more cautious

**EXPERT/ACADEMIC (Lilly-funded education session).** On [Keeping Current](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOhrtCDAiWOiyj39XmYEUKrL64RYUNuRg-2FAZ3fSgbyopW7BAn1GKMaCYBGk8pScRfLcQstJ5wU317AUDuLBkxzDNy3mtorLzt2-2BOKfiin-2Fp6dg-3D-3DIPHb_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNhMscky8Ph586lk3hDfbkJPKcZzQdbjKDjdypG-2FleidU2c1i33RKF-2BgWwAs9gj-2F5Ww8CdyinSS3ocGbNtetBiWMfirlsgJaTrEDY7cxUclJDg38nLxhV8qPjWI34NBhmAA-3D-3D) ("Solving the Alzheimer's Disease Biomarker Puzzle: Live, European Peer Workshop," Sep 28), **Charlotte Teunissen**, professor of neurochemistry at Amsterdam UMC, set out the European view. Also supported by "an independent educational grant from Lili."

**Why p-tau blood tests work, in one number.** In Alzheimer's, blood p-tau levels rise **"400% to 700%."** In routine labs, a change "must be more than 10 or 15%" to stand out from normal measurement noise. The older amyloid 42/40 ratio, by contrast, moves only about "10 to 50%," which is close to that noise. For p-tau-217 she showed accuracy scores (AUC, where 1.0 is perfect) of **"0.92 up to 0.96"** for detecting amyloid.

**But Europe still keeps it in the specialist clinic.** In primary care, adding blood tests to a family doctor's judgment lifted diagnostic accuracy to about **90%** in early studies, "but of course we need a few more studies to validate this. So the current intended use of blood-based biomarkers is in the specialist setting." In Europe, she says, CSF remains "the first-line test to accurately confirm AD diagnosis," while plasma "has the potential to replace CSF or amyloid PET imaging."

**Her warnings.** "The costs and reimbursements and the workflows are as yet unclear." She warned against "internet based testing, which leads to too many false positive results," and said testing "should be guided by the healthcare professional." She also gave a clean example of why **who** gets tested matters. With the same 90%-accurate test, a positive result is right **90%** of the time in a high-risk group, but only **69%** of the time in a lower-risk group.

**Why it moves numbers:** last week's US session described an FDA-cleared blood test for primary-care triage. This week's European view is a step behind: specialists first, primary care after more studies. For Roche and Fujirebio, which sell in both regions, Europe's adoption curve looks slower and more CSF-heavy. For the US lab companies, the warning about unguided testing matters too (see item 7).
### 5. A new tau biology paper: how the toxic protein travels

**EXPERT/ACADEMIC.** On [This Week in Neuroscience](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjA-2BgnruZxoZXINE-2B26tBYzV-2BFLWO8VXl4m5HtiWysMuNdJHPbqldbWo-2FXNpssAOPaL0cXp9t4M6HPSh-2F2xDS3NcCX18lfomMwKI1tE43IxxQ-3D-3DymVV_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNrNlPS-2BNLUij9b-2BrDCec0PwHi0Z38QOIR6QVFTvZhCO-2B2cXFy-2BVJMjKeQVxUX7ozoCK2QFb80UYxGgAjFOD7V9S-2B6axrIr0etPItjtLXI-2FOuVBxgltn2ANOpqXmgIABnEQ-3D-3D) ("Arc, tau, and Alzheimer's," Sep 29), **Jason Shepherd** of the University of Utah walked hosts **Vincent Racaniello** and **Tim Cheung** through his lab's Cell paper, "Arc mediates intercellular tau transmission via extracellular vesicles." It drew on Alzheimer's brain tissue from **Brad Hyman's** group at Mass General and was funded partly by the Chan Zuckerberg Initiative.

**The plain-English version.** Alzheimer's spreads through the brain in a predictable pattern, between connected neurons. Tau tangles sit **inside** cells, so something has to carry the toxic tau from one cell to the next. Shepherd's lab found a likely courier. **Arc** is a protein involved in memory that, oddly, evolved from an ancient virus-like element and can form virus-like shells. It packs toxic tau into tiny bubbles (called extracellular vesicles) that leave the cell.

* In rat neurons and in mice lacking Arc, "there was very little release of tau in extracellular vesicles." In the mouse brain, "we actually couldn't see any tau in these extracellular vesicles."
* Bubbles from normal mice could trigger tau clumping in a lab test; bubbles from Arc-lacking mice produced "no aggregation."
* Arc "seems to preferentially bind the phosphorylated version of tau, which is the toxic version."
* In human Alzheimer's brain tissue, "whenever there was a high level of tau, there were also high levels of ARC in these vesicles."

He framed the bigger picture this way: tau "is actually the culprit that kills the cell in the end, not the amyloid," which "seems to be almost a bystander to some degree." He was also candid about limits: "we did everything in mice," and the mouse model is "a sledgehammer" that produces far more tau than a human brain. The hosts also spent time on the US science-funding climate, calling it "a very, very tough time in science" amid fights over NIH grants.

**Why it moves numbers:** nothing here is near a drug. But it adds to the case behind antibodies that try to catch tau **between** cells, such as Eisai's E2814 and UCB/Roche's bepranemab. It also points to a possible new target: block the courier, not the cargo. Call it early science that supports the tau thesis, not a catalyst.
### 6. "Something like seven" companies are working on tau-lowering drugs

**PUNDIT/AUTHOR.** On [Causes or Cures](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjGbuMT7ot-2BdvBHbmH5wH9VoQLekNv2vtxlPh8jfSQ0AN1PLhCqwdYOsIDyqcwiiSQuf-2Fe1Tk3goWd8shk2l3vgiT9Jw8M16AnVq0-2BgKnWWEA-3D-3DUqCk_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNv91fFusHYLLzxy1uxfpcZMEkQAB6wW0GO942N7-2BW9S771-2BaHfcpARXYL7QYA54l-2Bl8ib9yVtCD8z8TYt8qC-2BXH99ZR5OfUznWYhlOGtqNyQBrErerduKKSPNdFCWZRx0A-3D-3D) ("Would You Want to Know? A Family's 50% Chance of Inheriting Dementia, with Robert Kolker," Sep 29), journalist **Robert Kolker** discussed his book **The Vanishing Family**, about a family carrying a mutation in the MAPT gene, which makes tau. It causes an inherited form of frontotemporal dementia (FTD).

His history of the field is blunt. Researchers put "all their chips on beta amyloid," partly through "groupthink" and grant incentives: "anybody who wanted to build a career trying to cure Alzheimer's disease was only going to get a grant if they were studying amyloid." On today's drugs: they "only reduce it by a little bit. And the disease seems to be slowing down, but it's certainly not a game changer."

His investable point is about **trial design**. Families with tau mutations are "very interesting potential test kitchens." "Let's say you wanted to knock out tau with a drug. Wouldn't you want to test it on this family to see if it worked?" They offer "a backdoor, a secret passageway" to an Alzheimer's treatment. And: "There are a lot of tau knockdown and knockout drugs that are in the pipeline by something like seven different pharma companies." He said first trials for this family's form of FTD "are coming soon," though "it's slow going."

**Why it matters:** a journalist, not a scientist or investor, so take the "seven companies" figure as a rough count. But the strategy he describes is real and worth watching: test tau-lowering drugs (such as Biogen's BIIB080) first in genetic tau diseases, where the biology is cleaner, then move into Alzheimer's.
### 7. Two cautionary podcasts from practitioners with something to sell

**PRACTITIONER WITH COMMERCIAL INTEREST: a lone case study, not evidence.** On [The Smartest Doctor in the Room](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOgOqR6PiuPELT-2BW4JbdXiu5R0H-2BGQFcpEl26vCfhRtLaURDPzhSE84ylgsIfFYPQBTe1H7Wtp7p86nPOobrwhQ1SMYfMYy7IyUbkC5YLwMcWw-3D-3DJkhF_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNhyfEBC3Sj-2B9ZONeh-2B2j73UtM20FsL5x8P4AWIaDBKllYxQZ4HdQV1r5sD-2FZd4cjHG2EDKBkP6KDo2KjCRsjWXK57pGtGBpOOnQJRcV603uE51V4hmHRIVDKhfF78NqMOg-3D-3D) ("Ep. 243 – Dr. Richard Horowitz's New Book on Ending Chronic Illness," Sep 29), Lyme-disease physician **Richard Horowitz** promoted his new book. He described a single patient whose blood p-tau-217 fell **63% in nine weeks** after his antibiotic protocol built around the old leprosy drug dapsone. He compared that to his own garbled reading of a recent Cochrane review of anti-amyloid drugs. He also said "about half" of his chronic-Lyme patients tested positive on Alzheimer's blood markers. **Treat all of this with real skepticism.** It's one patient, the author is selling a book and protocol, the episode carries a sponsor ad for a mold-testing company, and the claim that amyloid is mainly a response to Lyme infection is far outside the mainstream. The useful signal is a different one: "Quest Labs and LabCorp… started making available these Alzheimer's biomarkers," and practitioners well outside memory clinics are now ordering them. That is exactly the unguided testing Teunissen warned about in item 4.

**PRACTITIONER WITH COMMERCIAL INTEREST, plus an academic guest.** On [Alzheimer's Breakthrough with Dr. Josh Helman, MD](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOhp20DS5chpHtYcbhKU0XHQGaOkNNbPyYau-2FsJaTT5dumz8vwPu0KNxBCTm0KjOzkQyI9DPfPgwFHQLEg5fMwaDm4d0NaH1PzhneqGZF8Uv2Q-3D-3Dwkdj_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNutdYgIW9MqiejThAJO0xkoIBPyXGS9sZAjgb3bSY1ujTHzFBABl72Iemb94suEEmgck0ACqi1As3zi37AgFjg07bxlgZrar6UQMvETesfX0spp6avsf3qtdUQPKtIwXLg-3D-3D) ("Do You Really Need a Brain Scan When Memory Starts to Slip? | Dr. Bob Bilder, PhD #83," Oct 1), UCLA neuropsychologist **Bob Bilder** was skeptical of brain scans and of the drugs. The approved antibodies are "extremely expensive," "not really, you know, universally helpful," and "sometimes associated with side effects." On PET: "if there's no treatment that's going to help me really get better, why does it help me to know that I'm 90% confident I have Alzheimer's disease as opposed to 20% confident?" He prefers ruling out other causes, especially blood-vessel disease, and pushing lifestyle changes. Two caveats. First, his description of FDA-approved Alzheimer's PET (glucose or blood flow) leaves out the amyloid PET scans that actually decide drug eligibility. Second, the host advertises his own supplement line mid-episode. **Why it matters:** this is the consumer-facing skeptic view. It is a real drag on demand for testing and treatment among some patients, and the opposite of Terwilliger's "get me on the drug."
## The debate

**Do blood tests, at-home injections and broader coverage make anti-amyloid drugs a multi-billion-dollar franchise? Or do modest benefit, ARIA monitoring and diagnostic bottlenecks keep uptake structurally weak, while tau bets remain unproven?**

**Bull:** The machinery around these drugs is maturing fast. PET doctors call amyloid scanning "high-volume," and tau PET is just starting ([SNMMI](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOh-2Bhu4WQsRT5dTuFWxwGc19Rc1HTFFBCei4hzKlhruEd7oTXbX8WmsjC6TuIrNmA8T4Z2dq89V-2FR0nwFsm4TKUpCzCQmGH3UV1n3I-2BHQgtKqg-3D-3DApVr_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNttiEKctraFi92W5jQZipAHB5nMVNimvgSiLkw5d-2FHt6sUx-2B-2Bk0lkVT3aZDRGo-2BlpyHNVcacEOYgspTDAVmR9bjbUPhfTJulWxIQ261BO8hXPAv68g-2FPzUmyWUTujAysqg-3D-3D)). Blood p-tau rises "400% to 700%" in disease, with accuracy of 0.92–0.96 ([Keeping Current](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOhrtCDAiWOiyj39XmYEUKrL64RYUNuRg-2FAZ3fSgbyopW7BAn1GKMaCYBGk8pScRfLcQstJ5wU317AUDuLBkxzDNy3mtorLzt2-2BOKfiin-2Fp6dg-3D-3DsNTU_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNhXQtkmU997Gt0p4wL-2F0p48mIZb-2B00J-2B-2Fegqa3WQWe6W0SUUJtc0vDYvKuaXqoTs7dvfSqO-2BHv0AfYoP36WgeQ1RQq0IbuKxhTv5bCYc5j0BGqUq-2BTQfwzbv3cjpJX10Eg-3D-3D)). ARIA is "80 to 90%" symptom-free, mostly mild, and handled with a 10–15 minute MRI ([Keeping Current CME](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjqKLpm1GOLfL6DzQkJxlyZ4-2BeZlkRq4g4kTT6kOWJ4xU0Eu7PpNNvntqKsCpL34Kn-2F7ZCrkZvS8ki6k1DYxSW5jnr-2FinMkJgf-2F8w874sJJJA-3D-3DF1NR_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNg-2FbzbGqXobJ-2F4xHl8XlJGETCEeKMsL1gtflMlQiahRVPjRIYCggqAqYS4MwxYDAvg5TiXItlJ25jIj7uWENFqTzhD1DwBCn3Iv0YDrSlpk9GIRMWhtn8onG7kXhaySUJA-3D-3D)). Patients like Terwilliger are eager to start, and a blood test showed that his amyloid had cleared. The pool of 7.4 million Americans with the disease is large. And the next layer is coming: a cleared-amyloid group that needs a follow-on drug, a strong biological case for tau ([TWIN](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjA-2BgnruZxoZXINE-2B26tBYzV-2BFLWO8VXl4m5HtiWysMuNdJHPbqldbWo-2FXNpssAOPaL0cXp9t4M6HPSh-2F2xDS3NcCX18lfomMwKI1tE43IxxQ-3D-3DP6OS_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNvsZtGkwvuCVMcCs8k6RuXs45325CwPW7XNiAD1xbKYLnnLHXur3vLOrMCPVtHn18U3uZ03zFi1HSRu4nj7I6mKveLNPBaESdh3Ohl1-2BhKqOtcJ1LvMtEcAIa6eUGbM5pA-3D-3D)), and "something like seven" companies working on tau-lowering drugs ([Causes or Cures](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjGbuMT7ot-2BdvBHbmH5wH9VoQLekNv2vtxlPh8jfSQ0AN1PLhCqwdYOsIDyqcwiiSQuf-2Fe1Tk3goWd8shk2l3vgiT9Jw8M16AnVq0-2BgKnWWEA-3D-3DoljF_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNs5Hl2Hhq5LLdJyUN1Y1-2BfqzqD0TG3bmlilnhUgjEJ5VZyFYyheS-2FjQsbzt1yG9kONRr-2Bt9-2BKGnSfri0Et5ilkvF-2FIseKC05KhWOoIOpC7-2BIyMVS8iCYvFZ1HagEcmh3OQ-3D-3D)).

**Bear:** Every podcast this week also described friction. Readers are scarce: "not enough nuclear medicine physicians, period." At-home dosing still needs an MRI report "before you give the next dose." Insurers wouldn't pay for a follow-up PET. Europe still limits blood tests to specialists, with reimbursement "as yet unclear." The one real patient on a drug stopped after 18 months and copied a rival's stop-dosing guidance, which caps revenue per patient. Outside the specialist world, skeptics call the drugs "not really… universally helpful," and fringe practitioners are ordering blood tests on their own terms. Tau is still a story told in mice and book interviews. And once again there was **not one** Kisunla or Leqembi sales figure, patient-start number or IQLIK ramp data point on any podcast.

**Net:** Infrastructure is improving, and that is a real long-term positive for how many patients get diagnosed. But this week added a quieter concern about **how long patients stay on these drugs**. The more blood tests show amyloid has cleared, the easier it becomes to stop, and that cuts both ways for Biogen and Eisai. The next things that matter: actual uptake and persistence numbers, IQLIK's ramp, and the first named tau trial results.

## Stocks in play

**No company spoke on any podcast this week.** Everything below is a read-through from what was said, labeled as such.

* **BIIB (Biogen) / Eisai (4523 JP): read-through, mixed to negative on how long patients stay on treatment.** **Bull:** a patient eager to start, completing the full 18-month course, with a blood test showing amyloid cleared ([Brain Talk | Being Patient](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjiyImkYceMLurwElA53SlY7GsbU2NKLFkkoC4xGhgXZrVq50i9tfIxmq347zexsatHEEodhuUa2uhotuK11IMkRmPCsKQOpiI4Ko2-2BBvwQ-2Fw-3D-3DB-FT_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNnPPmlt5WOMD0hQxFoLq2bCYA617HSgty0GFiWMeq3IEqReJPq1QFYYoFwaaZUw7DPfT6aHY3KSDMj3ax5ogpcK2pWytcTAxkAqOxSZvP0b6-2BFTfpLAcmQQ0N1anB2tyRA-3D-3D)). That's a good efficacy anecdote. Tau science keeps building in support of Eisai's E2814 and Biogen's BIIB080 ([TWIN](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjA-2BgnruZxoZXINE-2B26tBYzV-2BFLWO8VXl4m5HtiWysMuNdJHPbqldbWo-2FXNpssAOPaL0cXp9t4M6HPSh-2F2xDS3NcCX18lfomMwKI1tE43IxxQ-3D-3DTHvV_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNpagalaZEJ8-2FpHqq9fJIIEsAZlKA8i8JoKO3z4C7Heq8jGtQJMIYV-2BdJMNvgIqQdLILqI9KLNcxzoJqv191oVxTzOd1FgoFXR3XqWqm25jq29ZrnFs1Sxr4DtAikFxiPCg-3D-3D)). **Bear:** he declined maintenance by applying Lilly's stop-dosing logic to Leqembi. At-home IQLIK still needs scheduled MRIs and careful distribution "before the report comes back" ([Keeping Current CME](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjqKLpm1GOLfL6DzQkJxlyZ4-2BeZlkRq4g4kTT6kOWJ4xU0Eu7PpNNvntqKsCpL34Kn-2F7ZCrkZvS8ki6k1DYxSW5jnr-2FinMkJgf-2F8w874sJJJA-3D-3DeZGO_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNi-2BimGPCPSVvBjy6fCy2gebD7n6mNyrFgbzUJd02GKEURtVos9-2BDFtp-2F7milPXwdfBaUYXLuZoEOpEHRZ-2FfBhXigYHJx1IdYow0X7OmpdupAOUacbVmclaxMKTViO0yJZQ-3D-3D)). **Next catalyst:** data on maintenance persistence and IQLIK uptake.
* **LLY (Eli Lilly): read-through, positive on Kisunla's message, neutral for the class.** **Bull:** its "you can stop once amyloid clears" message is reaching patients and neurologists, and is being used as the benchmark for the whole class. Lilly is also funding the doctor education that builds out the imaging and blood-test pathway (both Keeping Current sessions). Its Avid unit makes Tauvid, one of the two tau tracers discussed ([SNMMI](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOh-2Bhu4WQsRT5dTuFWxwGc19Rc1HTFFBCei4hzKlhruEd7oTXbX8WmsjC6TuIrNmA8T4Z2dq89V-2FR0nwFsm4TKUpCzCQmGH3UV1n3I-2BHQgtKqg-3D-3D16tW_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNuC-2BbiICpweXUT-2FGBJD6mLrPckwGD-2FleVVMt32veKb6NvdGVOgVyBaXLYh9dgcKb1gqDVbXJ-2B-2BYfNNAvP3OwZgQwdBYniGPnM46VS-2B3mqb2HP4-2B4G8wOuVWUmDcPZtqvkg-3D-3D), our note on the tracer). **Bear:** a time-limited course means less revenue per patient for Kisunla too. No sales, patient-start or infusion-capacity commentary for another week. **Next catalyst:** Kisunla uptake numbers and any at-home dosing progress.
* **LNTH (Lantheus): read-through, positive.** **Bull:** tau PET is "the tip of the iceberg," with major centers doing first clinical scans, and its prognostic role is "a piece of information we really don't have another way to get" ([SNMMI](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOh-2Bhu4WQsRT5dTuFWxwGc19Rc1HTFFBCei4hzKlhruEd7oTXbX8WmsjC6TuIrNmA8T4Z2dq89V-2FR0nwFsm4TKUpCzCQmGH3UV1n3I-2BHQgtKqg-3D-3DEsMY_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNlKhABZbcc2veOs2Lpa70vk4rMhm0TExPc0cWUZ3TuI8g-2Fj5Gd9uKvjOPPwRx7E9fVMf9T30bkINayXBLQH6hAFnzz9j04wRTgyu6GypgesCdN7ceartgp-2Fstx-2BlJHhjBg-3D-3D)). One of the two tau tracers discussed appears to be MK-6240 (our note). **Bear:** the bottleneck is readers, not tracer supply. Blood tests are replacing follow-up PET in at least some patients ([Brain Talk](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjiyImkYceMLurwElA53SlY7GsbU2NKLFkkoC4xGhgXZrVq50i9tfIxmq347zexsatHEEodhuUa2uhotuK11IMkRmPCsKQOpiI4Ko2-2BBvwQ-2Fw-3D-3D9UKG_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNuvuSz9fln-2F7dmf0OqVFI2I2LdxbGQE8MvAA8KBtFUXYD9I9J1WLxOkmbFlwa5vDCOn0W4KqvJj106femJBRzooD27Ou8RbvT1eXW-2FNuB7pYPKsHnmYszcwDweMrCHTR5Q-3D-3D)). **Next catalyst:** tau PET reimbursement and adoption data.
* **GEHC (GE HealthCare): read-through, positive.** **Bull:** it sponsored the SNMMI episode for its Vizamyl amyloid tracer. Amyloid PET is "high-volume," and safety MRIs remain mandatory even for at-home dosing ([Keeping Current CME](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjqKLpm1GOLfL6DzQkJxlyZ4-2BeZlkRq4g4kTT6kOWJ4xU0Eu7PpNNvntqKsCpL34Kn-2F7ZCrkZvS8ki6k1DYxSW5jnr-2FinMkJgf-2F8w874sJJJA-3D-3DunZ8_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNg39v2MA6ZMG9nJzuzw7HibHKyEFnV4PX0YLVihcZ45sc4oLfkt4dBj1fC0H2JErWnrofGZwG-2BG9TIaR9W6wmytqwCIbIaYQ9IetrSlOBonh1tkWuBYPYti6hJHtrouURg-3D-3D)). **Bear:** the MRI protocol runs fine on "older models," which limits any scanner upgrade cycle. **Next catalyst:** amyloid PET volume trends.
* **Roche (RHHBY / ROG SW) and Fujirebio (H.U. Group, 4544 JP): read-through, mixed.** **Bull:** strong expert validation that p-tau blood tests work (400–700% rises, AUC 0.92–0.96) ([Keeping Current](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOhrtCDAiWOiyj39XmYEUKrL64RYUNuRg-2FAZ3fSgbyopW7BAn1GKMaCYBGk8pScRfLcQstJ5wU317AUDuLBkxzDNy3mtorLzt2-2BOKfiin-2Fp6dg-3D-3Dsh5Y_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNqjMozEuDMR74e2axJ4xAzexb7Cf7-2BMoCDBt-2BMtPpQ-2BiXMIyYLeypNtxI1HUQ9ojThkkrvePAaDOPjCnliulh-2BU462PxQFEU8m98Wv9GNe-2BXqI5ySOksMs1y1hCy9nphrg-3D-3D)). **Bear:** in Europe, CSF is still "first-line," blood tests stay in specialist clinics, and reimbursement is "unclear." Nothing on Roche's trontinemab or bepranemab drug programs. **Next catalyst:** European guideline and reimbursement moves; any trontinemab update.
* **DGX (Quest) / LH (Labcorp) / QTRX (Quanterix) / C2N (private): read-through, positive volume, rising quality risk.** **Bull:** blood tests are being used for treatment monitoring when follow-up PET isn't covered, with repeat testing "twice a year at, at minimum" ([Brain Talk](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjiyImkYceMLurwElA53SlY7GsbU2NKLFkkoC4xGhgXZrVq50i9tfIxmq347zexsatHEEodhuUa2uhotuK11IMkRmPCsKQOpiI4Ko2-2BBvwQ-2Fw-3D-3DDp6v_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNrnX1gEqExidKh7K0aOALB10kxG7J2HiWh0y4DjJC2LeGU0seZY4xDqmesMWssGZZPlrciQfz2ZMZMQeIHTWqyfsAw8Pt2g-2BinEiTRyrdDPyhilkwLBNB8VIIYBPHJ6GDw-3D-3D)). Quest and Labcorp were named as making the tests widely available ([The Smartest Doctor in the Room](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOgOqR6PiuPELT-2BW4JbdXiu5R0H-2BGQFcpEl26vCfhRtLaURDPzhSE84ylgsIfFYPQBTe1H7Wtp7p86nPOobrwhQ1SMYfMYy7IyUbkC5YLwMcWw-3D-3DyT7c_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNjLb9-2B1ay1vPZI7GLFMQzIdyl7-2F-2F5nNmYOL-2FcUISFLk8zFTgx-2BW1-2FpH5-2FZBZyFAdLfks6YDNhCmPrJghhHKZlnBGgqbT-2BEFH3OyD1gTEPosPQbfu8sWPfW9JdUCcs-2BVtmw-3D-3D)). **Bear:** that same episode shows tests being ordered and read far outside mainstream guidance, the "too many false positive results" risk Teunissen flagged. Any backlash could bring tighter ordering rules. **Next catalyst:** payer coverage decisions for blood tests.
* **No podcast coverage this week (flagged, not invented):** Kisunla/Leqembi sales or patient-start figures; IQLIK ramp numbers; Roche trontinemab/bepranemab clinical data; AbbVie neuroscience (emraclidine, Vyalev, Cerevel assets); named tau programs with data (E2814, remternetug, BIIB080, ACI-35), TREM2 or complement; CMS coverage decisions, registry or prior-authorization changes; infusion centers/specialty pharmacy (OPCH); Cobenfy/KarXT, Parkinson's, Huntington's, ALS.

## Read-throughs

* **PET imaging (LNTH, GEHC, Lilly's Avid):** the best week for PET in a month. Amyloid PET is "high-volume," tau PET is just starting, and the constraint is trained readers ([SNMMI](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOh-2Bhu4WQsRT5dTuFWxwGc19Rc1HTFFBCei4hzKlhruEd7oTXbX8WmsjC6TuIrNmA8T4Z2dq89V-2FR0nwFsm4TKUpCzCQmGH3UV1n3I-2BHQgtKqg-3D-3DrmdT_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNgOf9g-2Bzvb3QwydvZ-2BF3mgv35vsiYI60mdyFZslmFk5DqWY3VnCoG5zVd6MMUb91V4yD8I3rJVx2Ky83YtDuj8OOOF1jvCo0dBYQhndU4LZklZSv4QbImkDV6MGKf-2BMWjg-3D-3D)). The offset: follow-up scans to check response are being replaced by blood tests when insurers say no ([Brain Talk](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjiyImkYceMLurwElA53SlY7GsbU2NKLFkkoC4xGhgXZrVq50i9tfIxmq347zexsatHEEodhuUa2uhotuK11IMkRmPCsKQOpiI4Ko2-2BBvwQ-2Fw-3D-3DhQZh_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNkX7dgYPCrv1ayeEUxoMrrxvomhG9kCCbXO2R3nyoNzXoDXaK-2FQ-2FpHfcAnzSG9V0CjkBjuBCXLrX76GOApUlKyO2leEeoVlhLWGWBS5qpACAyvQ-2BE6VxYr8gmIcnjPsDEA-3D-3D)). A fair summary: more first scans and tau scans, fewer repeat amyloid scans.
* **MRI (GEHC and peers):** an overlooked, steady winner. Every patient on these drugs needs a baseline MRI and scheduled safety scans, even at home ([Keeping Current CME](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjqKLpm1GOLfL6DzQkJxlyZ4-2BeZlkRq4g4kTT6kOWJ4xU0Eu7PpNNvntqKsCpL34Kn-2F7ZCrkZvS8ki6k1DYxSW5jnr-2FinMkJgf-2F8w874sJJJA-3D-3DGbuP_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNpEVWlZyel6KULqJnMy-2BVEN-2F0ukx893D2JtFrb7UoQ68hKrAKbGHJkcar-2BS3Wrt7dDjWIn-2FCTttZfQF-2BzRLMgfKHhxfFAzkDGYGRhZj-2FmIo-2FqkzNg43VL9ZtekLsryP9Rw-3D-3D)). AI tools for counting microbleeds and grading ARIA were mentioned as something reports should now disclose.
* **Blood diagnostics (Roche, Fujirebio, QTRX, C2N, DGX, LH):** use is spreading into three areas: diagnosis, monitoring after treatment, and (less helpfully) alternative-medicine practices. The US is moving faster than Europe ([Keeping Current](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOhrtCDAiWOiyj39XmYEUKrL64RYUNuRg-2FAZ3fSgbyopW7BAn1GKMaCYBGk8pScRfLcQstJ5wU317AUDuLBkxzDNy3mtorLzt2-2BOKfiin-2Fp6dg-3D-3DBMSN_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNh2OxoziFS3YjvY8lbbCiPub-2FBOUcJsm1SshNFA-2BRgXEl9fUxWRm1WXPwdCyiesowGcOZELk3GYH8rre7BQdAu8NY3OB9hWG3drjp0Vkgxc7WZJUl3FHssSYDv1yQD7reg-3D-3D)).
* **Infusion centers (OPCH):** nothing direct. Two small negatives by inference: patients stopping after the first 18 months instead of moving to maintenance, and the long-run shift to at-home injections. One small positive: the MRI-before-dose rule keeps the treatment in a supervised, scheduled setting.
* **Partners (Eisai, Roche):** Eisai faces the same persistence question as Biogen. Roche's diagnostics arm gains validation, but in Europe it competes with CSF testing.
* **Broader CNS pipeline:** tau biology is getting more concrete (the Arc courier finding), and genetic tau families are being lined up as early test groups ([Causes or Cures](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjGbuMT7ot-2BdvBHbmH5wH9VoQLekNv2vtxlPh8jfSQ0AN1PLhCqwdYOsIDyqcwiiSQuf-2Fe1Tk3goWd8shk2l3vgiT9Jw8M16AnVq0-2BgKnWWEA-3D-3Dzjid_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNhAp6enSd4iY3xSEgxZDu2n8E8baJ5oAhy4SyDFK2P7t84kEyq-2FTKbj0eKjqLAsYgHmXFWEvK00va6XPomDp6Np0BkqlPkoc-2BDUBq4KIEyEOxYM7y-2F9wG40-2FRWD1GAMaDA-3D-3D)). Nothing on psychiatry, Parkinson's or Huntington's this week.

## What changed vs last week

**No company-level news, but the conversation moved from diagnosis to what happens after treatment.** Last week's podcasts were about getting patients **into** the funnel. This week's best material was about what happens at the far end: stopping treatment, checking whether amyloid is gone, and the trial gap afterward.

**Blood tests picked up a new job.** Last week, blood tests were a diagnosis tool, with a US specialist describing a primary-care rule-out test and a specialist rule-in test. This week a patient used one as a **monitoring tool** after his insurer wouldn't cover a follow-up PET ([Brain Talk](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjiyImkYceMLurwElA53SlY7GsbU2NKLFkkoC4xGhgXZrVq50i9tfIxmq347zexsatHEEodhuUa2uhotuK11IMkRmPCsKQOpiI4Ko2-2BBvwQ-2Fw-3D-3D7aJu_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNmiYHRsj2hIWjXoyYhFNmz45db4XCp-2FKVhJ9sukNV4qXWvwuou9gk5mA55K3UMBf35FEOjKdTmDVedB4ncpsioltiqVEiQcol1S0uSQq-2FsiSRbRfe5TnVdNljRsVl1x7jA-3D-3D)). That's new, and it matters for both lab and PET volumes.

**A regional difference, not a contradiction.** Last week's US session described an FDA-cleared blood test for primary care. This week's European workshop said "the current intended use of blood-based biomarkers is in the specialist setting," with CSF still "first-line" ([Keeping Current](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOhrtCDAiWOiyj39XmYEUKrL64RYUNuRg-2FAZ3fSgbyopW7BAn1GKMaCYBGk8pScRfLcQstJ5wU317AUDuLBkxzDNy3mtorLzt2-2BOKfiin-2Fp6dg-3D-3DHNRx_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNpwWH-2BfDCCJYNtXLE8z0-2Bb-2BKWjWMPy6JeOkKo4U6MzXk48381pRehT-2FyZ4dnXG50MBNBo47raA6cfkIIPE-2BVtYQp4ckVswnAaDrklq6JTfOxoWc7sUb7J-2F1ymA-2Fcbljzrg-3D-3D)). Both are true; Europe is simply further behind.

**PET's outlook improved again.** Two weeks ago a CEO mused that PET could become "archaic." Last week a specialist pushed back: PET is the tie-breaker for unclear blood results. This week nuclear-medicine doctors described high amyloid volume, a tau PET market just opening, and a shortage of readers ([SNMMI](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOh-2Bhu4WQsRT5dTuFWxwGc19Rc1HTFFBCei4hzKlhruEd7oTXbX8WmsjC6TuIrNmA8T4Z2dq89V-2FR0nwFsm4TKUpCzCQmGH3UV1n3I-2BHQgtKqg-3D-3DkHiN_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNmQb6hVohZx-2B0PTdokdLnGM2sgsTm5e6cpsemq6lY3Ja7JxZd0RbV-2FCN1u2pKsIzoy13GOGIgrAL2ko-2BTE1Nc0LNqh6sCWojQxJRkDAXOFIASaRYA3OMrHtPo8tTdqM7JA-3D-3D)). The "PET is dying" idea looks increasingly wrong for first scans. Repeat scans are a different story.

**At-home dosing got a new caveat.** We had treated at-home injections as a fix for the infusion bottleneck. This week a radiology panel said the MRI schedule still applies, and drug shipments must be timed to the safety reports ([Keeping Current CME](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjqKLpm1GOLfL6DzQkJxlyZ4-2BeZlkRq4g4kTT6kOWJ4xU0Eu7PpNNvntqKsCpL34Kn-2F7ZCrkZvS8ki6k1DYxSW5jnr-2FinMkJgf-2F8w874sJJJA-3D-3Dw6dC_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNsrlsBmx-2BXCZ1J2o0dOh09j1XmWz9obPlCB40DN-2B158gLWd4WEmsF4GOGcOeb00OOq8t4iBTEXChvkTe-2F-2F4JAIP5TkXHrs2aJujyIyfs7qC9eZ-2FSxHHTkyy8mzfC49BmQQ-3D-3D)). That's the first time this caveat has surfaced in our coverage.

**Tau, week three.** Three weeks ago Biogen's CEO said lowering tau moved cognition "for the very first time." Last week an Edinburgh scientist called tau-lowering drugs "super exciting and promising." This week brought a mechanism paper ([TWIN](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjA-2BgnruZxoZXINE-2B26tBYzV-2BFLWO8VXl4m5HtiWysMuNdJHPbqldbWo-2FXNpssAOPaL0cXp9t4M6HPSh-2F2xDS3NcCX18lfomMwKI1tE43IxxQ-3D-3DAaCG_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNvsg9iA6kg5hQclFupDbzLzjfrGdg2REcxdlBJcMxqEu4TCp-2FMTX6nIRc5fid1EaBa9QXJGwWxWd-2BbePFo5SuXbEf06k9nxn6TxPT33oE3q-2FScr16Q4mjaPR6N5yGapM8g-3D-3D)) and a rough count of "something like seven" companies in the race ([Causes or Cures](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOjGbuMT7ot-2BdvBHbmH5wH9VoQLekNv2vtxlPh8jfSQ0AN1PLhCqwdYOsIDyqcwiiSQuf-2Fe1Tk3goWd8shk2l3vgiT9Jw8M16AnVq0-2BgKnWWEA-3D-3DZUC__7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNtBjW1ZEShpodPCO0TG8hxO1lf3Jd0PZtHNqljY-2Bo4SZ1ic-2F9OXNb-2BzOk5xbocyYD2QxfNP6jt7XfFyCnRnfRKdE7IFZ0-2BCtPSPk08Z0jXFufbl7WAsKjNlDaAbgU1lw5A-3D-3D)). Still no named program, no new data.

**A tension on inflammation.** Last week Prof. Spires-Jones said "all of the anti-inflammatories tested have failed" in Alzheimer's. This week a Lyme physician promoted an anti-inflammatory antibiotic based on one patient ([The Smartest Doctor in the Room](http://url7324.matterfact.com/ls/click?upn=u001.idHmPrr2Geh7KYLAsTy7NkrIVb-2FgA4pmf2rMXQwGcOgOqR6PiuPELT-2BW4JbdXiu5R0H-2BGQFcpEl26vCfhRtLaURDPzhSE84ylgsIfFYPQBTe1H7Wtp7p86nPOobrwhQ1SMYfMYy7IyUbkC5YLwMcWw-3D-3DinYQ_7mLGwmUci-2BLaXswv9WX1yTgqn3Wad-2FotHhzHgSNAZbW4MfeJYIjqfdhx-2FqVs-2FVJ3ZYORWBFVRFj-2FIM-2BwtIjLNpc5O-2FNch7zXspngcVt6WLYjMxY5YOooerbIj-2Fe1Jeucj2AySy2GmIouARVVVQQQwml5UTEz1J7yGxx38RO5gAvh4cj7rhOitjZT-2FyB-2BCCRnr0oBh15mkAQTYQ0R50Id1g-3D-3D)). We side with the controlled-trial record.

**The honest gap list:** no Kisunla or Leqembi launch or sales figures; no IQLIK ramp numbers; no Roche drug data; no AbbVie neuroscience update; no named tau program with data; no CMS coverage or prior-authorization news; nothing on infusion-center economics, Cobenfy, Parkinson's, Huntington's or ALS.

---

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