Last updated: October 6, 2026
Patisiran sodium, marketed as Onpattro by Alnylam Pharmaceuticals, established the first FDA-approved RNA interference treatment for hereditary transthyretin-mediated amyloidosis. Its commercial position has weakened as Alnylam shifted patients toward Amvuttra, a longer-acting subcutaneous transthyretin-lowering therapy. Onpattro remains protected by formulation and use patents beyond the expiration of its U.S. orphan-drug exclusivity in 2025, but its long-term revenue trajectory depends on retention in patients who require intravenous therapy and on the pace of generic or follow-on competition.
What is patisiran sodium and how is Onpattro used?
Patisiran sodium is a small interfering RNA therapeutic formulated in a lipid nanoparticle. It targets transthyretin messenger RNA in the liver, reducing production of both mutant and wild-type transthyretin.
| Attribute |
Onpattro |
| Active ingredient |
Patisiran sodium |
| Product |
Onpattro |
| Developer and marketer |
Alnylam Pharmaceuticals |
| FDA approval |
August 10, 2018 |
| Indication |
Polyneuropathy caused by hereditary transthyretin-mediated amyloidosis in adults |
| Administration |
Intravenous infusion once every three weeks |
| Delivery technology |
Lipid nanoparticle |
| FDA review pathway |
Priority Review and Breakthrough Therapy designation |
| U.S. regulatory exclusivity |
Orphan-drug exclusivity through August 2025 |
| Key commercial limitation |
Intravenous administration and premedication burden |
Patients receive Onpattro by intravenous infusion, generally with corticosteroid, acetaminophen, and antihistamine premedication to reduce infusion-related reactions. Vitamin A supplementation is also required because transthyretin transports retinol-binding protein and vitamin A.
The FDA approved Onpattro on the basis of the APOLLO study, which showed improvement relative to placebo on neurologic impairment and quality-of-life measures in hereditary transthyretin amyloidosis with polyneuropathy (U.S. Food and Drug Administration [FDA], 2018).
How has the patisiran sodium market developed?
Onpattro created the commercial RNAi market but did not retain the most favorable dosing profile within Alnylam’s transthyretin franchise. Amvuttra, approved in 2022, is administered subcutaneously once every three months. That dosing advantage has encouraged switching from Onpattro and limited the product’s long-term growth.
Market drivers
The principal demand drivers are:
- Diagnosis of hereditary transthyretin amyloidosis in earlier disease stages.
- Greater genetic testing among patients with unexplained neuropathy or cardiomyopathy.
- Expansion of specialist treatment centers.
- Use in patients who cannot tolerate or do not respond adequately to transthyretin stabilizers.
- Clinical evidence supporting early transthyretin reduction.
The major constraints are infusion-center capacity, treatment burden, high annual cost, limited disease prevalence, payer authorization requirements, and competition from oral stabilizers and longer-acting RNA medicines.
Disease and treatment economics
Hereditary transthyretin amyloidosis is a rare disease with substantial heterogeneity. Patients may present with polyneuropathy, cardiomyopathy, autonomic dysfunction, or mixed disease. The commercial market is therefore driven less by broad primary-care prescribing and more by referral networks involving neurologists, cardiologists, geneticists, and amyloidosis centers.
Onpattro’s infused delivery system creates a recurring healthcare-services component. That can support adherence in controlled infusion settings but can reduce convenience compared with subcutaneous or oral alternatives.
What has been the financial trajectory for Onpattro?
Onpattro generated rapid post-launch growth, followed by slower expansion as Alnylam introduced Amvuttra and diversified its rare-disease portfolio.
Public filings show the following broad trajectory:
| Period |
Financial development |
| 2018 |
Commercial launch after FDA approval; initial revenue limited by launch timing |
| 2019-2020 |
Rapid uptake among hereditary transthyretin polyneuropathy patients |
| 2021 |
Continued growth, supported by wider diagnosis and treatment-center adoption |
| 2022 |
Product matured while Amvuttra entered the market |
| 2023-2024 |
Revenue pressure from patient conversion to Amvuttra and competing transthyretin therapies |
Alnylam reported Onpattro net product revenue of approximately $400 million to $470 million annually during the product’s peak period, depending on accounting period and geographic reporting. The product’s contribution has since become less important relative to Amvuttra, Givlaari, Oxlumo, and royalty income. Alnylam’s annual reports identify Onpattro as a mature product while describing Amvuttra as the strategic growth product in transthyretin amyloidosis (Alnylam Pharmaceuticals, 2023, 2024).
Revenue exposure and downside risk
Onpattro’s revenue exposure is concentrated in a rare-disease franchise with high gross-to-net variability. Discounts, government rebates, patient support programs, and international pricing controls affect reported net sales.
The main revenue risks are:
- Conversion from intravenous Onpattro to quarterly Amvuttra.
- New prescriptions for Wainua, marketed by AstraZeneca and Ionis Pharmaceuticals.
- Continued use of Pfizer’s Vyndaqel and Vyndamax in transthyretin cardiomyopathy.
- Potential entry of follow-on RNAi products after patent barriers weaken.
- Reimbursement restrictions in markets outside the United States.
The product remains economically relevant because many patients require long-term treatment and because the underlying disease is chronic. Its growth profile, however, is no longer that of a first-in-class launch product.
When does Onpattro lose exclusivity?
Onpattro’s U.S. orphan-drug exclusivity runs for seven years from the FDA approval date and therefore ended on August 10, 2025, subject to the statutory scope of the exclusivity and regulatory interpretation. Orphan exclusivity prevents approval of the same drug for the same indication when the statutory conditions are met. It does not prevent all competing products or all uses of the same active ingredient.
| Exclusivity or protection |
Date or status |
| FDA approval |
August 10, 2018 |
| Seven-year orphan-drug exclusivity |
August 10, 2025 |
| Small-molecule NCE exclusivity |
Not the principal commercial protection |
| Patent protection |
Extends beyond orphan exclusivity for selected claims |
| Generic entry before patent expiry |
Dependent on patent certifications, litigation, and product equivalence |
Because Onpattro is a complex lipid nanoparticle formulation, the end of orphan exclusivity does not automatically produce immediate generic substitution. A competitor would need to address active ingredient identity, lipid composition, particle characteristics, manufacturing controls, sterility, potency, and clinical or pharmacologic comparability.
What patents protect patisiran sodium and Onpattro?
Onpattro is protected by a combination of patents covering RNA sequences, transthyretin gene silencing, lipid nanoparticle compositions, manufacturing methods, and therapeutic use. The exact enforceability and expiration dates depend on patent-term adjustment, terminal disclaimers, patent-family continuity, and jurisdiction.
Publicly identified U.S. patent families associated with patisiran and related Alnylam RNAi technology include:
| Patent or patent family |
General subject matter |
Commercial relevance |
| U.S. Patent No. 9,428,535 |
Transthyretin-directed RNAi compositions and methods |
Active-ingredient and gene-silencing claims |
| U.S. Patent No. 10,183,013 |
RNAi therapeutic compositions and delivery technology |
Potential formulation and product coverage |
| U.S. Patent No. 10,501,546 |
Lipid nanoparticle and RNA delivery claims |
Manufacturing and composition barrier |
| Related continuation families |
Formulation, dosing, and treatment claims |
May extend protection for selected commercial uses |
Patent expiry for early RNAi and sequence claims can occur before expiry of later formulation patents. The practical launch date therefore depends on the surviving claims, not the earliest expiration in the family.
What formulations are protected by Onpattro patents?
The most commercially important formulation claims cover the lipid nanoparticle delivery system. Those claims can address:
- Specific ionizable lipids.
- Helper phospholipids.
- Cholesterol and polyethylene glycol-lipid components.
- Particle size and encapsulation characteristics.
- Ratios among lipid components.
- Encapsulation of transthyretin-directed siRNA.
- Manufacturing and purification processes.
Formulation patents are strategically important because a competitor may be unable to copy the marketed product exactly even after sequence claims expire. A non-infringing alternative formulation could require a different regulatory pathway and additional development work.
Are there method-of-use patents for Onpattro?
Method-of-use patents may cover treatment of hereditary transthyretin amyloidosis, reduction of transthyretin production, treatment of polyneuropathy, dosing schedules, and patient-selection criteria. Their commercial value is narrower than composition patents when the product has a single dominant indication, but they can delay or complicate a labeled generic launch.
What is the Orange Book status of patisiran sodium?
Onpattro is listed in the FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, commonly called the Orange Book, with patent information submitted by the sponsor. The Orange Book is relevant to an abbreviated new drug application because a generic applicant must address listed patents through Paragraph I, II, III, or IV certifications.
The commercially significant Orange Book issues are:
- Whether all relevant formulation patents are listed.
- Whether a generic applicant challenges listed patents under Paragraph IV.
- Whether Alnylam files suit within 45 days of receiving a Paragraph IV notice.
- Whether a 30-month stay delays approval.
- Whether the applicant seeks a label that avoids patented methods of use.
Patisiran sodium is a chemically defined siRNA drug rather than a protein biologic. Biosimilar terminology is therefore generally less applicable than generic, follow-on, or complex-drug terminology. FDA approval may proceed through an ANDA if the applicant can establish the required pharmaceutical equivalence and bioequivalence. A 505(b)(2) pathway could be relevant for a materially different formulation or delivery system.
Which companies are challenging or competing with Onpattro?
The competitive market includes both direct transthyretin silencers and non-silencing therapies.
| Product |
Company |
Mechanism |
Administration |
Competitive effect |
| Amvuttra |
Alnylam |
siRNA transthyretin silencing |
Subcutaneous every three months |
Primary internal substitute for Onpattro |
| Vyndaqel/Vyndamax |
Pfizer |
Transthyretin stabilization |
Oral daily |
Strong competitor, especially in cardiomyopathy |
| Tegsedi |
Ionis Pharmaceuticals |
Antisense transthyretin silencing |
Subcutaneous |
Earlier-generation RNA competitor |
| Wainua |
Ionis/AstraZeneca |
Antisense transthyretin silencing |
Subcutaneous monthly |
Newer competitor for polyneuropathy |
| Eplontersen development programs |
Ionis/AstraZeneca |
Ligand-conjugated antisense |
Subcutaneous |
Potential convenience and market-share pressure |
| Diflunisal |
Generic manufacturers |
Transthyretin stabilization, off-label |
Oral |
Low-cost alternative in selected patients |
Amvuttra is the most direct threat because it targets the same biological pathway and is controlled by the same company. Alnylam can migrate patients within its own franchise while preserving transthyretin-silencing revenue, but this process reduces Onpattro-specific sales.
How does Onpattro compare with Amvuttra?
| Factor |
Onpattro |
Amvuttra |
| Active ingredient |
Patisiran sodium |
Vutrisiran |
| Delivery |
Intravenous lipid nanoparticle |
Subcutaneous conjugated RNAi |
| Dosing |
Every three weeks |
Every three months |
| Premedication |
Generally required |
Lower infusion-related burden |
| Commercial status |
Mature product |
Growth product |
| Patient convenience |
Lower |
Higher |
| Main strategic role |
Established treatment and clinical base |
Franchise migration and market expansion |
Amvuttra’s dosing schedule is the central commercial advantage. Onpattro may remain preferred for patients who are already stable on intravenous treatment, require supervised administration, or have clinical circumstances that favor the established formulation. New starts are more likely to favor the less frequent subcutaneous option.
What patent litigation and Paragraph IV risks affect Onpattro?
No broad, high-profile U.S. generic launch against Onpattro has reshaped the market in the same way that Paragraph IV litigation has affected major oral small-molecule products. The principal litigation risk remains prospective.
A generic applicant could challenge:
- The validity of RNA sequence claims.
- Written-description or enablement of broad RNAi claims.
- Obviousness of lipid nanoparticle compositions.
- Patent-term calculations.
- The scope of listed formulation claims.
- The availability of a carve-out label for patented uses.
Alnylam’s strongest litigation position is likely to involve claims that combine the patisiran sequence with the specific lipid nanoparticle formulation. Challenges to broad platform patents may have greater commercial value for a competitor than challenges limited to the Onpattro label.
What licensing deals support the patisiran sodium franchise?
Alnylam’s RNAi platform has been supported by strategic collaborations, including its historical relationship with Sanofi. Sanofi exercised rights in Alnylam’s rare-disease programs during the development period, while Alnylam later consolidated control over its commercial RNAi portfolio. The parties’ collaboration history remains relevant to royalty economics, milestone obligations, and rights in certain territories.
Alnylam also has a broad commercial relationship with Roche for RNAi medicines in other therapeutic areas, but that relationship is not the principal commercial driver of Onpattro revenue. Onpattro economics are primarily tied to Alnylam’s own commercial organization and its transthyretin franchise.
What is the FDA regulatory status of Onpattro?
Onpattro remains an FDA-approved treatment for hereditary transthyretin-mediated amyloidosis with polyneuropathy in adults. FDA approval does not cover all forms of transthyretin amyloidosis, and Onpattro has not displaced the need for separate regulatory evidence in cardiomyopathy.
The regulatory profile includes:
- FDA approval in 2018.
- Priority Review.
- Breakthrough Therapy designation.
- Orphan-drug designation.
- Postmarketing safety monitoring for infusion reactions, liver effects, ocular effects related to vitamin A metabolism, and other risks.
The regulatory distinction between polyneuropathy and cardiomyopathy affects both market size and patent-use strategy. A successful cardiomyopathy indication could materially expand revenue, but Onpattro’s cardiomyopathy development history has not produced the same commercial position as its polyneuropathy approval.
How strong is the patent estate for patisiran sodium?
The patent estate is strong in the near term but less durable than the broader Alnylam RNAi platform.
Its strengths are:
- Multiple patent layers rather than a single composition patent.
- Formulation claims tied to lipid nanoparticle delivery.
- Manufacturing know-how that is difficult to reproduce.
- Regulatory complexity associated with a sterile injectable RNA product.
- High switching costs in a rare-disease treatment setting.
Its weaknesses are:
- Orphan exclusivity has ended.
- Early platform and sequence patents can expire before later formulation patents.
- Amvuttra reduces the commercial value of defending every Onpattro claim.
- A competitor may pursue a differentiated formulation rather than copy the product exactly.
- The product has a narrow labeled population.
The estate is therefore more effective at delaying direct substitution than at preserving Onpattro’s historical growth rate.
What generic launch scenarios exist for Onpattro?
Three launch scenarios are commercially plausible:
Scenario 1: No near-term direct generic
A competitor avoids Onpattro because of formulation complexity, limited market size, and the need to compete against Amvuttra. Onpattro declines gradually through patient switching and continued use in established patients.
Scenario 2: Paragraph IV challenge followed by settlement
A generic applicant files an ANDA with Paragraph IV certifications. Alnylam sues, triggering a potential 30-month stay. The parties settle for a future launch date, possibly with a license, supply arrangement, or restrictions on the competing formulation.
Scenario 3: Follow-on formulation
A competitor develops a different siRNA delivery system and pursues an ANDA or 505(b)(2) application. This pathway could avoid some formulation patents but would require substantial analytical, clinical, and manufacturing support.
The highest probability commercial threat is gradual erosion from competing therapies rather than an immediate, high-volume generic launch.
How does Onpattro compare with competing transthyretin drugs?
Onpattro remains clinically important but commercially disadvantaged on administration frequency. Amvuttra offers a more convenient version of the same therapeutic strategy. Pfizer’s Vyndaqel franchise has a major position in transthyretin cardiomyopathy and benefits from oral administration. Wainua expands the antisense category with a less burdensome delivery profile than Tegsedi.
Alnylam’s economic objective is therefore likely to maximize the transthyretin franchise rather than preserve Onpattro as a standalone growth product. Onpattro provides clinical experience, physician relationships, and a treatment base, while Amvuttra captures new starts and conversions.
Key Takeaways
- Patisiran sodium is marketed as Onpattro by Alnylam Pharmaceuticals.
- FDA approval occurred on August 10, 2018, for hereditary transthyretin-mediated amyloidosis with polyneuropathy in adults.
- Seven-year U.S. orphan-drug exclusivity ended on August 10, 2025.
- Onpattro generated several hundred million dollars in annual revenue at peak but has entered a mature-to-declining phase.
- Amvuttra is the principal commercial substitute and is likely to accelerate patient switching because it is administered subcutaneously once every three months.
- Patent protection extends beyond orphan exclusivity through RNAi, formulation, lipid nanoparticle, manufacturing, and method-of-use claims.
- Generic entry is technically difficult because Onpattro is a complex sterile lipid nanoparticle product.
- The principal competitive risks are Amvuttra, Wainua, Vyndaqel/Vyndamax, and future follow-on RNA therapies.
- Onpattro’s future value lies more in durable treatment of established patients and franchise support than in new-patient growth.
FAQs About Patisiran Sodium and Onpattro
Is patisiran sodium a biologic or a generic drug?
Patisiran sodium is a chemically defined siRNA drug delivered through a lipid nanoparticle. It is generally evaluated as a complex drug rather than a conventional protein biologic. Biosimilar terminology is less applicable than generic or follow-on product terminology.
Does Onpattro treat transthyretin cardiomyopathy?
Onpattro’s FDA-approved indication is hereditary transthyretin-mediated amyloidosis with polyneuropathy in adults. It should not be treated as having the same approved cardiomyopathy indication as products specifically authorized for that use.
Can patients switch from Onpattro to Amvuttra?
Switching is clinically possible, but the decision depends on physician assessment, disease status, tolerability, payer coverage, and treatment history. Amvuttra’s quarterly subcutaneous dosing is its principal convenience advantage.
What is the annual cost of Onpattro treatment?
The commercial cost varies by country, negotiated payer discounts, patient weight, dosing, and infusion charges. List-price comparisons do not represent net manufacturer revenue or total treatment cost.
Will a generic version of Onpattro launch immediately after orphan exclusivity expires?
No. Orphan exclusivity expiration removes one regulatory barrier but does not eliminate listed patents, formulation complexity, manufacturing requirements, or litigation risk. A generic or follow-on launch would depend on the approval pathway and surviving patent claims.
References
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Alnylam Pharmaceuticals, Inc. (2023). 2022 annual report. U.S. Securities and Exchange Commission.
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Alnylam Pharmaceuticals, Inc. (2024). 2023 annual report. U.S. Securities and Exchange Commission.
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U.S. Food and Drug Administration. (2018, August 10). FDA approves first-of-its-kind targeted RNA-based treatment for rare disease. https://www.fda.gov
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U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA Orange Book.
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U.S. Patent No. 9,428,535. (2016). Compositions and methods for inhibiting expression of transthyretin.
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U.S. Patent No. 10,183,013. (2019). RNA interference compositions and methods.
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U.S. Patent No. 10,501,546. (2019). Lipid nanoparticle compositions and methods of use.
