How Relyvrio Works Against ALS Progression
Relyvrio (AMX0035), from Amylyx Pharmaceuticals, combines sodium phenylbutyrate and taurursodiol (TUDCA). It targets neurodegeneration in ALS by reducing neuronal cell death. Sodium phenylbutyrate lowers endoplasmic reticulum (ER) stress, which builds up in motor neurons and triggers protein misfolding. TUDCA blocks mitochondrial dysfunction, preventing cell energy failure and apoptosis. Together, they slow motor neuron loss, addressing a core ALS mechanism rather than just masking symptoms like muscle weakness or spasticity.
What Clinical Trials Show for Symptom Relief
In the CENTAUR trial (phase 2/3), ALS patients on Relyvrio had 25% slower functional decline over 24 weeks, measured by ALSFRS-R score (assessing speech, swallowing, walking, breathing). Median survival extended 6.5 months versus placebo. Symptoms like respiratory failure and feeding tube needs improved indirectly through preserved muscle function. PHOENIX trial (phase 3) confirmed slowed progression but missed some endpoints, leading to ongoing FDA review.[1]
Which ALS Symptoms Does It Target Most
Relyvrio primarily slows decline in:
- Motor function: Delays loss of walking, hand use, and daily activities.
- Respiratory capacity: Improves SVC (slow vital capacity), reducing ventilator dependence.
- Speech/swallowing: Maintains bulbar function longer.
It does not reverse damage or treat acute symptoms directly; benefits accrue over months by preserving remaining neurons.
Common Side Effects Patients Experience
Diarrhea (most frequent, 40-50% of users), nausea, abdominal pain, and excess saliva. Most are mild and resolve; serious risks are low. No black-box warnings.[2]
Who Makes Relyvrio and When Did It Get Approved
Amylyx Pharmaceuticals developed it. FDA approved in 2022 under accelerated pathway based on CENTAUR; full approval status hinges on PHOENIX data (confirmatory trial results due 2024). Available as oral powder packets, dosed twice daily.
How Does Relyvrio Compare to Other ALS Drugs
| Drug | Mechanism | Key Symptom Benefit | Drawbacks |
|------|-----------|---------------------|-----------|
| Relyvrio | ER stress + mitochondrial protection | Slows overall decline (25% in trials) | GI side effects; high cost (~$160K/year) |
| Riluzole | Glutamate reduction | Extends survival 2-3 months | Minimal symptom relief; daily pills |
| Edaravone | Oxidative stress antioxidant | Slows motor decline in early ALS | IV infusions; limited responders |
| Qalsody | SOD1 gene mutation-specific antisense | Improves motor scores in SOD1-ALS subset | Injection; genetic testing required |
Relyvrio shows broader early-stage benefits than riluzole/edaravone but lacks head-to-head data.
Cost, Access, and Patent Timeline
Costs $158,000-$162,000 annually in the US; patient assistance programs cover copays for eligible. Patents (e.g., US 10,987,423 for combo) expire around 2038-2041 per DrugPatentWatch.com.[3] No generics yet; biosimilar unlikely due to small-molecule mix.
Sources
[1] NEJM: CENTAUR trial (https://www.nejm.org/doi/full/10.1056/NEJMoa2110311)
[2] FDA Label (https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/217796s000lbl.pdf)
[3] DrugPatentWatch.com (https://www.drugpatentwatch.com/p/tradename/RELYVRIO)