Medically reviewed by Dr. Jyoti Rao, Consultant, Medical Affairs | Last reviewed August 2026
Key Takeaways
- Gene silencers reduce hepatic transthyretin production (siRNA or ASO), which is a different mechanism from stabilizers as it doesn't clear amyloid already deposited in the heart.
- Patisiran is approved for the polyneuropathy of hereditary ATTR; it was studied in the APOLLO-B cardiomyopathy trial but didn’t receive an FDA cardiomyopathy indication.
- Eplontersen is approved for the polyneuropathy of hereditary ATTR; its cardiomyopathy use is investigational in the ongoing CARDIO-TTRansform trial.
- Vutrisiran is currently the only gene silencer with a U.S. FDA-approved indication for ATTR-CM.
- Stabilizer plus silencer combination therapy is an investigational concept, not an approved regimen.
Gene Silencers Lower Transthyretin Production, Not Deposited Amyloid
Gene silencers act upstream of amyloid formation by reducing how much transthyretin the liver makes. Two approaches are used: small interfering RNA (siRNA), as with patisiran and vutrisiran, and antisense oligonucleotides (ASO), as with eplontersen. This is mechanistically distinct from the stabilizer strategy, which holds the existing transthyretin tetramer together. The shared limitation is important to state plainly: lowering production reduces the supply of transthyretin available for amyloid formation; it shouldn’t be described as directly clearing established myocardial amyloid. So expectations should be framed around slowing the disease rather than reversing established damage. The same evidence discipline applies across emerging ATTR-CM therapies and the mechanistic reading in ATTR-CM preclinical research.
Patisiran Is Approved for Polyneuropathy, Not Cardiomyopathy
Patisiran is an siRNA approved in the United States for the polyneuropathy of hereditary ATTR amyloidosis. It was also evaluated in cardiomyopathy; in the APOLLO-B trial, the primary endpoint was change in six-minute walk distance at 12 months, and patisiran was reported to preserve functional capacity compared with placebo. Although APOLLO-B showed preservation of functional capacity and other clinical measures, patisiran didn’t receive a U.S. FDA indication for ATTR-CM. Patisiran shouldn’t be described as an approved ATTR-CM therapy, and any cardiomyopathy use would be off-label and would need to be interpreted separately from its approved polyneuropathy indication and the APOLLO-B evidence.
Eplontersen Is Approved for Polyneuropathy, with Cardiomyopathy Under Study
Eplontersen is an antisense oligonucleotide approved in the United States for the polyneuropathy of hereditary ATTR amyloidosis. Its role in cardiomyopathy is investigational and is being tested in the dedicated phase 3 cardiomyopathy trial CARDIO-TTRansform, which enrolled a large cardiomyopathy population with a primary composite of cardiovascular mortality and recurrent cardiovascular events. As of the time of publication, the trial results had not been reported and eplontersen isn't approved for ATTR-CM, so its cardiomyopathy use should be described as investigational pending the trial readout rather than as established therapy.
Vutrisiran Is the Gene Silencer Currently Approved for ATTR-CM
Among the gene silencers, vutrisiran is the one currently approved in the United States for transthyretin amyloid cardiomyopathy, with an indication to reduce cardiovascular outcomes in eligible patients. Importantly, the gene-silencer class isn't uniformly approved for cardiomyopathy, and clinicians should read each agent against its own label and phenotype rather than treating the class as interchangeable.
Regulatory status differs by agent and by phenotype, as summarized below.
| Agent | Class | Polyneuropathy (PN) | Cardiomyopathy (CM) | Key CM trial |
|---|---|---|---|---|
| Patisiran (ONPATTRO) | siRNA | Approved | Not approved (CRL 2023) | APOLLO-B |
| Eplontersen (WAINUA) | Antisense oligonucleotide | Approved | Investigational | CARDIO-TTRansform (ongoing) |
| Vutrisiran (AMVUTTRA) | siRNA | Approved | Approved (2025) | HELIOS-B |
Combination Therapy Is an Investigational Concept
Because stabilizers and silencers act through different mechanisms, combining them—stabilizing existing transthyretin while lowering new production—is a logical hypothesis that has drawn interest. It remains an investigational concept rather than an established regimen, with no approved combination product or combination indication in ATTR-CM. Any discussion of combination therapy should be framed as forward-looking, with efficacy and safety to be defined by dedicated study rather than inferred from the single-agent data for each class.
Clinical Decision Point
The key discipline with gene silencers in ATTR-CM is to read each agent against its own label and phenotype rather than generalizing from the class. Patisiran and eplontersen are approved for polyneuropathy, not cardiomyopathy; vutrisiran is the silencer currently approved for cardiomyopathy; and combination therapy is investigational. Because regulatory status in this space is evolving, the current product label and trial status should be confirmed before treatment decisions are made.
Frequently Asked Questions
What are gene silencers in ATTR-CM?
Gene silencers are therapies that lower the liver's production of transthyretin, using either small interfering RNA (patisiran, vutrisiran) or antisense oligonucleotides (eplontersen). They differ from stabilizers, which hold the existing transthyretin protein together, and they don't clear amyloid already deposited in the heart.
Is patisiran approved for ATTR-CM?
No. Patisiran is approved for the polyneuropathy of hereditary ATTR amyloidosis. It was studied in the APOLLO-B cardiomyopathy trial and showed preservation of six-minute walk distance versus placebo, but it didn’t receive an FDA cardiomyopathy indication, and the manufacturer didn’t pursue that indication in the United States.
Is eplontersen approved for ATTR-CM?
No, not for cardiomyopathy. Eplontersen is approved for the polyneuropathy of hereditary ATTR amyloidosis. Its cardiomyopathy use is investigational and is being evaluated in the phase 3 CARDIO-TTRansform trial, which remains investigational and has not yet reported results at the time of publication.
Which gene silencer is approved for ATTR-CM?
Among the gene silencers, vutrisiran is currently approved in the United States for transthyretin amyloid cardiomyopathy, with an indication to reduce cardiovascular outcomes in eligible patients. Patisiran and eplontersen remain approved for the polyneuropathy of hereditary ATTR rather than for cardiomyopathy.
Can stabilizers and silencers be combined?
Combining a stabilizer with a silencer is a plausible, investigational concept because the two act through different mechanisms, but there’s no approved combination product or combination indication in ATTR-CM. It should be treated as forward-looking rather than established care.
Related Reading
Part of the Spotlight On ATTR-CM resource center.
Related Emerging and Alternative Topics
See the Evidence
References:
- World Heart Federation Consensus on Transthyretin Amyloidosis Cardiomyopathy (ATTR-CM). Global Heart
- ONPATTRO (patisiran) prescribing information. U.S. Food and Drug Administration
- Patisiran Treatment in Patients with Transthyretin Cardiac Amyloidosis (APOLLO-B). New England Journal of Medicine
- WAINUA (eplontersen) prescribing information. U.S. Food and Drug Administration
- CARDIO-TTRansform: A Study of Eplontersen in Participants With Transthyretin-Mediated Amyloid Cardiomyopathy (ATTR-CM). ClinicalTrials.gov NCT04136171
- AMVUTTRA (vutrisiran) prescribing information. U.S. Food and Drug Administration
This content is intended for healthcare professionals for educational purposes and isn't a substitute for individual clinical judgment. It was developed with AI assistance and reviewed by a qualified healthcare professional for clinical accuracy prior to publication.