The Cochrane review published on Thursday — pooled from seventeen phase-III trials covering 20,342 patients — concluded that the clinical effect of anti-amyloid Alzheimer's drugs on cognitive decline was "absent or trivial." [1] It is Monday morning. The Food and Drug Administration has not issued a statement. Biogen, which sells lecanemab as Leqembi, has not filed an 8-K or released a press notice. Eli Lilly, which sells donanemab as Kisunla, has not. The Centers for Medicare and Medicaid Services has not moved to reconsider its 2023 National Coverage Determination. The infusions scheduled for this morning in clinics across the country will proceed on the standing protocol. Medicare will pay roughly $26,500 per patient per year for each one. [2]

The paper's Sunday reporting on the fourth day of silence named the pattern: when an agency legally obliged to evaluate new evidence against an active approval does not speak, the absence is itself reportable. Monday advances that pattern to its fifth day, and Monday is the first weekday in the window where an FDA announcement, a CMS guidance document, or a congressional oversight letter could ordinarily be expected. None has appeared as of press time.

The template for this mode of reporting is the paper's ongoing coverage of a parallel silence. The April 18 feature on the National Institutes of Health's refusal to comment on the helium-MRI triage rubric — then five days in, now eight — established that institutional non-response during wartime has a measurable half-life, and that the responsible agency passes the initial news cycle with the question still unanswered. The Alzheimer's file is now the second-longest active example in the paper's war-second-order-effects thread. The consumer of the drug cannot know what the regulator thinks; the clinician administering the drug cannot know either.

What Cochrane actually wrote

The review was authored by Francesco Nonino, a neurologist and epidemiologist at Italy's IRCCS Institute of Neurological Sciences in Bologna, and Edo Richard, a professor of neurology at Radboud University Medical Centre in the Netherlands. It pooled results across seven anti-amyloid monoclonal antibodies — aducanumab, bapineuzumab, crenezumab, donanemab, gantenerumab, lecanemab, and solanezumab — in patients with mild cognitive impairment or mild Alzheimer's dementia. [3] The pooled effect on the Clinical Dementia Rating-Sum of Boxes was a standardized mean difference of -0.06, statistically significant but well below the threshold that defines a clinically meaningful change. [4] Amyloid-related imaging abnormalities — the microhemorrhages and cerebral edema the drugs produce — were more than ten times as common on active drug as on placebo for the edema category. [4]

The review's finding was unambiguous. "There is now a convincing body of evidence converging on the conclusion that there is no clinically meaningful effect," Nonino said in the Cochrane press release. [1] Edo Richard went further: "Existing approved drugs offer some benefit for some patients, but there remains a high unmet need for more effective treatments. Sadly, anti-amyloid drugs do not offer this and bring additional risks." [1]

The response to the review from within the industry has been visible. Eisai, which partners with Biogen on lecanemab, told the Associated Press the review was "scientifically deeply flawed by inappropriately combining ineffective antibodies." [5] The Alzheimer's Society in the United Kingdom issued a statement defending the two approved drugs while acknowledging the review's methodology. [6] John Hardy, the British biologist who first proposed the amyloid hypothesis and who has consulted for Biogen, Eisai, and Eli Lilly, told AFP the paper was "silly" and "should not have been published." [5] What the response has not contained is a statement from the agency that approved the drugs, the agency that pays for them, or the manufacturers whose marketing claims the review's data would bear on.

The five-day clock

Friday was the first full business day after publication. Saturday and Sunday were the weekend. Monday is the fifth day and the first weekday when the machinery of federal drug regulation is fully staffed and operational. A Center for Drug Evaluation and Research statement does not convene on 96 hours' notice; an advisory committee hearing requires weeks. But a press statement acknowledging receipt of the Cochrane review, indicating a timeline for internal analysis, or committing to a public comment would ordinarily take hours, not days. None has appeared.

Medicare's coverage decision is governed by a separate procedural architecture. The 2023 National Coverage Determination requires that patients receiving lecanemab or donanemab be enrolled in a clinical registry that captures safety and efficacy outcomes. [2] The registry mechanism was established on the premise that clinical benefit was uncertain and needed monitoring. Cochrane's review is the most comprehensive synthesis of the evidence the registry was designed to gather. A CMS technical advisory memorandum responding to new evidence of this scope has a longer procedural runway than an FDA statement, but the agency has not acknowledged the review at all. The Senate Finance Committee and the House Energy and Commerce Committee, which oversee CMS, have not announced an inquiry or requested testimony.

The infusion chair

Approximately 40,000 Americans have received lecanemab or donanemab since the 2023 approvals, according to analyst estimates pooled by the Congressional Budget Office. [2] Every one of them had a baseline MRI, a confirmatory PET scan, an intravenous line, and an infusion every two weeks for lecanemab or every four weeks for donanemab. Each infusion is billed to Medicare at a rate that produces the $26,500 annualized figure. The clinician who orders the infusion is now administering a drug the highest-ranked independent evidence body in medicine has classified as offering absent or trivial clinical benefit, with side effects serious enough that Britain and France declined to reimburse. [5] The clinician cannot point to a Monday-morning bulletin from the FDA or a Monday-morning memo from CMS. Neither has come.

The paper's position as of Sunday was that a Monday without movement would be its own response. Monday has now come. The response is the absence. Biogen's share price closed at $247.80 on Friday, up 0.4% on the session. Lilly's closed at $739.12. Neither tape reflects a market pricing in imminent regulatory action, which is itself an information signal: the institutional investors who trade these names have the Cochrane review, have the regulators' five-day silence, and are pricing the silence as continuation rather than inflection.

What it would take

Three developments could reverse the pattern. First, an FDA advisory committee could be convened on accelerated notice — the agency has done it before, last in 2021 over the aducanumab approval itself. Second, a Senate Finance or House Energy and Commerce hearing could request CMS testimony; the calendar is clear for a late-April session. Third, a major academic medical center — Johns Hopkins, UCSF, Mayo, Mass General — could issue internal guidance pausing new starts pending agency response. [7] Any of these would break the silence. None appeared in the first five days.

The war second-order thread carried six items on Sunday; it carries seven on Monday, and the seventh is the one that has changed least. [8] The helium silence is on Day 8. The Alzheimer's silence is on Day 5. The pediatric MRI patient triaged behind the adult is a concrete body. The Alzheimer's patient in the infusion chair is a concrete body too. Both are waiting for agencies whose statutory role is to speak about them. On Monday morning, both agencies continue to decline the role.

-- NORA WHITFIELD, Chicago