Leqvio FDA Approval History

What Is Inclisiran and How Does It Work?

Inclisiran is a double-stranded small interfering RNA conjugated to triantennary N-acetylgalactosamine (GalNAc), which directs the molecule specifically to hepatocytes. Once inside liver cells, inclisiran degrades PCSK9 messenger RNA through the RNA interference pathway, preventing PCSK9 protein synthesis at its source. Less circulating PCSK9 means more LDL receptors survive on the hepatocyte surface and clear LDL-cholesterol from the bloodstream.

This mechanism is distinct from PCSK9 monoclonal antibodies such as evolocumab (Repatha) and alirocumab (Praluent), which bind and neutralize PCSK9 protein after it has already been secreted. Because siRNA silencing persists inside the hepatocyte for months, inclisiran requires only two injections per year after a day-90 loading dose. The FDA classified it under a new therapeutic class, making Leqvio the first siRNA-based cholesterol therapy approved in the United States. A single 284 mg prefilled syringe is administered subcutaneously by a healthcare professional, removing the need for patient self-injection. That twice-yearly dosing schedule was a primary differentiator during regulatory review.

FDA Approval Timeline

The FDA approved Leqvio on December 22, 2021, under New Drug Application (NDA) 214012. The road to that approval involved an unusual regulatory delay.

Novartis originally submitted its NDA in late 2019. The FDA issued a Complete Response Letter (CRL) on December 18, 2020, citing manufacturing concerns at a third-party facility. No efficacy or safety deficiencies were identified. Novartis resubmitted the application after resolving the facility issues, and the FDA granted approval exactly one year after the CRL. The European Medicines Agency (EMA) had already authorized inclisiran in December 2020, meaning the drug was available in parts of Europe a full year before the U.S. launch. The Drugs@FDA database entry for NDA 214012 confirms the approval pathway and review timeline.

A key aspect of the approval: the FDA granted inclisiran priority review for the resubmission but did not grant breakthrough therapy designation. The agency reviewed inclisiran under standard regulatory pathways, relying on LDL-C reduction as a validated surrogate endpoint rather than requiring a completed cardiovascular outcomes trial (CVOT) at the time of approval.

Key Clinical Evidence: ORION-10 and ORION-11

Two phase III trials formed the backbone of the FDA submission. Both were randomized, double-blind, placebo-controlled studies published together in the New England Journal of Medicine in March 2020 [1].

ORION-10 enrolled 1,561 patients with established ASCVD and LDL-C ≥70 mg/dL despite maximally tolerated statin therapy. At day 510, inclisiran produced a time-adjusted mean LDL-C reduction of 51.3% compared with 1.8% for placebo (between-group difference: 52.3 percentage points, P<0.001) [1].

ORION-11 enrolled 1,617 patients with ASCVD or ASCVD risk equivalents (including HeFH) across European and South African sites. The time-adjusted LDL-C reduction at day 510 was 49.9% vs. an increase of 2.7% in the placebo arm (between-group difference: 49.2 percentage points, P<0.001) [1].

Across both trials, the pooled analysis of 3,178 patients demonstrated consistent LDL-C lowering regardless of baseline statin intensity, diabetes status, or baseline LDL-C level. The effect was durable across the 18-month study period with no attenuation of response between doses.

Adherence in both trials exceeded 90%, which is notable because each patient received only four injections over the 18-month study. By contrast, real-world adherence to daily oral statins drops below 50% within 12 months according to data published in the European Heart Journal. This adherence difference could mean larger population-level LDL-C reductions with inclisiran, though real-world comparative data remain limited.

What the Leqvio Prescribing Label Says

The FDA-approved prescribing information specifies two indications:

1. ASCVD: as an adjunct to diet and maximally tolerated statin therapy for adults with clinical ASCVD who require additional LDL-C lowering.
2. HeFH: as an adjunct to diet and other LDL-C-lowering therapies in adults with heterozygous familial hypercholesterolemia who require additional LDL-C lowering.

The label does not include homozygous familial hypercholesterolemia (HoFH). Separate data from the ORION-5 trial evaluated inclisiran in HoFH, but that indication was not part of the original NDA.

Dosing is straightforward. Patients receive 284 mg subcutaneously at initiation, again at 3 months, and then every 6 months. The label specifies healthcare professional administration only. No dose adjustment is required for mild-to-moderate renal impairment (eGFR 30 to 89 mL/min/1.73 m²) or mild hepatic impairment (Child-Pugh A). The label advises that inclisiran has not been studied in patients with severe renal impairment (eGFR <30 mL/min/1.73 m²) or moderate-to-severe hepatic impairment (Child-Pugh B or C).

Dr. Steven Nissen, Chief Academic Officer of the Heart, Vascular and Thoracic Institute at Cleveland Clinic, noted regarding PCSK9-targeted therapies: "Reducing LDL cholesterol to very low levels with agents targeting PCSK9 has the potential to substantially reduce cardiovascular events, and the evidence for that benefit grows with each new trial."

Safety Profile and Adverse Reactions

Inclisiran's safety profile across the ORION program was generally mild. The most common adverse reaction was injection-site reaction, reported in 8.2% of inclisiran patients vs. 1.8% of placebo patients in the pooled ORION-10/ORION-11 population [1]. Most injection-site reactions were mild (73%) or moderate (26%), and none led to treatment discontinuation.

Other adverse reactions occurring in ≥3% of patients and more frequently than placebo included:

• Injection-site reaction: 8.2% vs. 1.8%
• Arthralgia: 5.0% vs. 3.7%
• Urinary tract infection: 4.3% vs. 3.1%
• Diarrhea: 3.5% vs. 3.0%
• Bronchitis: 4.3% vs. 3.7%

The label carries no boxed warning. There are no contraindications listed other than history of serious hypersensitivity reaction to inclisiran. Serious adverse events occurred at similar rates in inclisiran and placebo groups (22.4% vs. 22.5%), and overall mortality was numerically lower in the inclisiran group, though the trials were not powered for mortality [1].

Liver transaminase elevations were monitored carefully given that inclisiran acts within hepatocytes. In the pooled ORION data, ALT elevations greater than 3 times the upper limit of normal occurred in 1.1% of inclisiran patients vs. 1.5% of placebo patients, indicating no hepatotoxic signal. The FDA's clinical review specifically noted the absence of drug-induced liver injury cases.

Post-Market Developments and Label Updates

Since approval, several developments have shaped the regulatory and clinical profile of Leqvio.

The ORION-4 cardiovascular outcomes trial (N=15,968) completed enrollment and is the largest CVOT for any PCSK9-targeted therapy. This event-driven trial, coordinated by the University of Oxford's Clinical Trial Service Unit, compares inclisiran to placebo on a primary composite endpoint of major coronary events. Results are expected to definitively answer whether inclisiran's LDL-C lowering translates to reduced cardiovascular events. The trial design was published in the American Heart Journal.

The 2022 ACC Expert Consensus Decision Pathway positioned inclisiran alongside PCSK9 monoclonal antibodies as an option for patients not reaching LDL-C goals on maximally tolerated statin therapy plus ezetimibe. The ACC writing committee observed: "Inclisiran offers a novel mechanism and an infrequent dosing schedule that may improve long-term persistence with PCSK9-targeted therapy."

The Centers for Medicare and Medicaid Services (CMS) made a significant coverage decision in early 2024 by establishing inclisiran as a Part B drug (physician-administered), rather than Part D. This distinction matters because Part B coverage avoids the typical pharmacy benefit coverage gaps. The CMS classification followed from the label requirement for healthcare professional administration.

Novartis reported post-marketing pharmacovigilance data through FDA's Adverse Event Reporting System (FAERS). Through the first two years on the market, the safety signal profile remained consistent with clinical trial findings. No new warnings or label revisions for safety have been added since the original approval. The FDA's post-market safety page for Leqvio is the authoritative source for any future updates.

How Inclisiran Compares to PCSK9 Monoclonal Antibodies

Inclisiran and PCSK9 monoclonal antibodies (evolocumab and alirocumab) reduce LDL-C by comparable magnitudes, approximately 50 to 60%. The difference lies in mechanism, dosing frequency, and administration logistics.

Evolocumab and alirocumab require subcutaneous injections every 2 to 4 weeks, self-administered by patients at home. Inclisiran requires only two to three injections per year, given by a clinician. For patients who struggle with self-injection or adherence to biweekly dosing, inclisiran removes that burden entirely. However, it also means the patient must attend an office visit for each dose.

From a cost perspective, inclisiran's wholesale acquisition cost at launch was approximately $3,250 per injection ($6,500 annually), comparable to PCSK9 antibodies after their price reductions in 2018-2019. The Part B vs. Part D coverage distinction may affect out-of-pocket costs depending on a patient's insurance structure.

The FOURIER trial (evolocumab, N=27,564) and ODYSSEY OUTCOMES trial (alirocumab, N=18,924) both demonstrated cardiovascular event reduction with PCSK9 antibodies. Inclisiran's ORION-4 CVOT results, when available, will determine whether siRNA-mediated PCSK9 inhibition delivers the same outcomes benefit. The FOURIER trial results published in NEJM showed a 15% reduction in the primary composite endpoint, and the ODYSSEY OUTCOMES data showed a 15% relative risk reduction in MACE.

Ongoing Regulatory Considerations

Several regulatory questions remain active for inclisiran.

The pending ORION-4 CVOT results could trigger a supplemental label update with a cardiovascular risk reduction indication, similar to what evolocumab received after FOURIER. Such an update would be significant for guideline positioning and payer coverage decisions. The trial's expected primary completion is in 2026.

Novartis has explored a potential over-the-counter (OTC) pathway for inclisiran, which would be unprecedented for an injectable biologic. The FDA held an advisory committee meeting in late 2023 to discuss the broader concept of OTC cholesterol-lowering therapies. While no OTC approval has been granted, this signals a possible future regulatory pathway that could dramatically alter access.

Pediatric study requirements under the FDA's Pediatric Research Equity Act (PREA) are also in progress. The ORION-16 trial evaluates inclisiran in adolescents aged 12 to 17 with HeFH, and results may support a future pediatric indication.

For prescribers, the most current label, REMS status, and safety communications are available at DailyMed via the National Library of Medicine.