AMBIGUOUS RESULTS

Clene plans ALS accelerated-approval NDA built on a biomarker, not survival data

FDA told Clene an NfL biomarker signal from small, partly aged trials may support filing, but the agency wants proof the biomarker predicts clinical benefit before approval.

By AppliedXLJuly 13, 2026Trial NCT04098406

Executive Summary

Clene intends to file for accelerated approval of its ALS drug on the strength of a blood biomarker, after the FDA signaled that pathway may be viable, but the agency has not called the biomarker validated and wants more evidence connecting it to patient benefit.
The filing leans on a set of small trials, including one whose own primary motor-neuron endpoint did not separate drug from placebo, so the case for approval rests on a biomarker readthrough rather than a demonstrated clinical effect.
No ALS drug has ever reached approval through a neurofilament-based surrogate pathway, so this filing would set precedent for the mechanism rather than follow one.
Clene also plans to start a confirmatory Phase 3 trial shortly after filing, the study that would need to convert the biomarker signal into a measured clinical outcome if accelerated approval is granted.

The catalyst

Clene Inc., through its subsidiary Clene Nanomedicine, said the FDA's final minutes from a recent Type C meeting (a mid-development regulatory discussion) stated the company's "proposed data may be capable of supporting the submission and review of an under the accelerated approval pathway" for CNM-Au8 in ALS. The agency separately noted that NfL, a blood marker of nerve-cell damage, "could potentially serve as a reasonably likely surrogate endpoint" for that pathway. Clene said it intends to file in the third quarter of 2026 under the Subpart H accelerated approval pathway (21 CFR 314.510), and to start a Phase 3 confirmatory trial in the first quarter of 2027. [NDA, DOC-1]

The condition attached

The FDA's minutes carried a specific instruction: the submission must show that the magnitude of NfL reduction is reasonably likely to predict clinical benefit in ALS patients, not simply that NfL moved. The agency separately asked Clene to include additional analyses connecting the reported NfL reduction to clinical outcomes, which the company said it has prepared for the filing. "The filing of an NDA submission represents an important milestone for CNM-Au8 and for the ALS community," said Rob Etherington, Clene's President and CEO. That statement describes the filing step; whether the underlying data satisfy the FDA's own condition is the question the review will resolve. After

The supporting trial

One of the trials underpinning the filing, RESCUE-ALS (NCT04098406), completed with 45 patients randomized to CNM-Au8 or placebo, a modest upward revision from its original 42-patient target. Its registered primary endpoint measured electromyography-based motor-neuron loss (Motor Unit Number Index) over 36 weeks, and the trial's own posted results describe least-squares mean differences between arms without establishing separation that met the primary endpoint. The trial's primary completion date moved from April 2021 to July 2021 during conduct, a three-month shift, and results were not posted to the registry until July 2024, three years after completion. The NDA plan also draws on the Phase 2 HEALEY ALS Platform Trial and its open-label extension, and an NIH-sponsored expanded-access protocol for CNM-Au8, per the company's disclosure. NCT04098406+1

Regulatory context

CNM-Au8 already holds Orphan Drug Designation from the FDA for ALS, a designation tied to unmet need in a rare disease rather than to any judgment about approvability. No approval history for CNM-Au8 exists yet, and no ALS therapy has previously reached approval through a neurofilament-based accelerated pathway, so this filing would be a first test of that regulatory route in this disease rather than a follow-on to an established one. After

The competitive field

CNM-Au8's mechanism, targeting mitochondrial function and the NAD pathway, has no other industry-sponsored trial registered against the same target in ALS. The closest named ALS programs in active development, tofersen from Biogen and masitinib from AB Science, work through different mechanisms, an antisense approach against SOD1 mRNA and a small-molecule KIT inhibitor, respectively, so neither serves as a direct comparator to CNM-Au8's biomarker claim. That leaves the accelerated-approval question resting on Clene's own data rather than on a body of comparable biomarker precedent in this indication.

This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.