Repatha vs Leqvio: Switching Between Them Explained

How Each Drug Works

Repatha and Leqvio both raise LDL receptor availability on liver cells, but they do it at completely different points in the PCSK9 pathway. Understanding those differences is the first step in deciding which agent fits a patient's situation.

Evolocumab: Protein-Level Blockade

Evolocumab is a fully human IgG2 monoclonal antibody. It binds circulating PCSK9 protein directly, preventing PCSK9 from degrading LDL receptors on hepatocytes. The effect is near-immediate: LDL-C begins falling within days of the first injection, reaches nadir around two weeks, and then partially rebounds before the next dose. The FDA approved evolocumab in August 2015 for adults with heterozygous or homozygous familial hypercholesterolemia and for clinical ASCVD requiring additional LDL-C lowering on maximally tolerated statin therapy.

Inclisiran: Gene-Silencing at the Source

Inclisiran is a synthetic small interfering RNA conjugated to triantennary N-acetylgalactosamine (GalNAc). After subcutaneous injection, GalNAc delivers the molecule selectively to hepatocytes via asialoglycoprotein receptors. Inside the cell, inclisiran silences PCSK9 messenger RNA before the protein is ever synthesized. The result is a sustained 50% LDL-C reduction that persists for roughly six months per dose, explaining the twice-yearly maintenance schedule. The FDA approved inclisiran in December 2021 for the same broad ASCVD and familial hypercholesterolemia indications as evolocumab.

Because inclisiran suppresses PCSK9 production rather than neutralizing existing protein, its LDL-lowering effect does not show the peak-and-trough fluctuation seen with monoclonal antibody dosing. That pharmacokinetic difference has practical implications when switching.

LDL-C Efficacy: How the Numbers Compare

Both agents produce substantial LDL-C reductions on top of statins, but the trial designs differ enough that direct numeric comparison requires care.

FOURIER: Evolocumab's Efficacy Data

In the FOURIER trial (N=27,564), evolocumab 140 mg every two weeks or 420 mg monthly added to statin therapy reduced LDL-C by a mean of 59% from baseline, bringing the median on-treatment LDL-C to 30 mg/dL. FOURIER, published in NEJM 2017, enrolled patients with established ASCVD and a baseline LDL-C of at least 70 mg/dL on optimized statin therapy. The primary endpoint was a composite of cardiovascular death, myocardial infarction, stroke, unstable angina requiring hospitalization, or coronary revascularization.

At 48 weeks, the LDL-C reduction was 59% (P<0.001). At the median follow-up of 2.2 years, the drug reduced the primary endpoint by 15% (hazard ratio 0.85, 95% CI 0.79 to 0.92, P<0.001) and reduced the key secondary endpoint of cardiovascular death, MI, or stroke by 20% (HR 0.80, P<0.001) [1].

ORION-10 and ORION-11: Inclisiran's Efficacy Data

ORION-10 (N=1,561, primary prevention-enriched U.S. Population) and ORION-11 (N=1,617, mixed U.S./European ASCVD population) are the twin phase 3 trials underpinning inclisiran's approval. Published together in NEJM 2020, both trials tested inclisiran 284 mg at day 1, day 90, then every six months.

In ORION-10, inclisiran reduced LDL-C by 52.3% from baseline at day 510 (P<0.001 vs. Placebo). In ORION-11, the reduction was 49.9% at day 510 (P<0.001 vs. Placebo) [2]. Neither trial was powered or designed to detect MACE reduction. The ongoing ORION-4 outcomes trial is expected to report cardiovascular event data in the mid-2020s.

The Key Gap: Proven MACE Reduction

Evolocumab has published, replicated evidence of reduced cardiovascular events. Inclisiran does not yet, at least not in a completed outcomes trial. For patients in whom the primary goal is reducing the risk of a second heart attack or stroke, that distinction matters today, not after ORION-4 reports.

Cardiovascular Outcomes: What the Trials Actually Proved

Evolocumab's 15% MACE Reduction

FOURIER's 15% relative risk reduction in the primary composite endpoint translated to an absolute risk reduction of 1.5 percentage points over 2.2 years [1]. The number needed to treat (NNT) for the primary endpoint was approximately 67 over that period. Secondary analyses showed the benefit grew over time, with the 20% reduction in cardiovascular death, MI, or stroke becoming more pronounced in the second year of follow-up.

The 2022 ACC/AHA Guideline on Cardiovascular Risk Reduction gives PCSK9 inhibitors a Class I recommendation for patients with very high-risk ASCVD whose LDL-C remains 70 mg/dL or higher on maximally tolerated statin plus ezetimibe therapy. The guideline states: "In very high-risk patients with clinical ASCVD, if the LDL-C level remains 70 mg/dL or higher while receiving maximally tolerated statin and ezetimibe therapy, adding a PCSK9 inhibitor is recommended (Class I, LOE: A)."

Inclisiran's Outcomes Gap

Inclisiran's approval rested on LDL-C reduction as a surrogate endpoint, consistent with FDA's approach to prior PCSK9 inhibitor applications. The FDA review memorandum for inclisiran acknowledges this explicitly, noting that LDL-C reduction is an established surrogate for cardiovascular events. Whether the twice-yearly siRNA approach translates to the same or better MACE reduction than the monoclonal antibody approach remains an open question until ORION-4 reports. Observational analyses and network meta-analyses have not identified a safety signal with inclisiran, but they cannot confirm equivalence of clinical benefit.

Dosing Schedules and Adherence

Evolocumab's Biweekly or Monthly Rhythm

The 140 mg every-two-weeks regimen uses a single autoinjector pen. The 420 mg monthly dose requires three 140 mg pens administered within 30 minutes at a single sitting. Patients self-inject at home after training. Missing a dose by more than seven days requires restarting the dosing schedule rather than simply catching up, per the prescribing label. That requirement makes adherence a genuine clinical concern: real-world data from commercial claims databases suggest 12-month persistence rates for PCSK9 monoclonal antibodies range from 30% to 60%, depending on the population and payer mix. A 2019 analysis published in JAMA Cardiology found that only 45.7% of patients initiated on a PCSK9 inhibitor remained on therapy at one year.

Inclisiran's Twice-Yearly Office Model

Inclisiran is designed to be administered by a healthcare provider, not self-injected at home, at least under the current U.S. Prescribing model. That structure eliminates patient-level adherence decisions between office visits. A patient who shows up for their six-month appointment gets their dose; the next decision point is six months away.

The tradeoff is scheduling dependency. Patients who travel frequently, live in rural areas, or have limited access to infusion centers or physician offices may find the office-visit requirement burdensome. Some practices administer inclisiran during routine cardiology follow-up, bundling the injection with the visit, a model that fits patients who see their cardiologist twice a year anyway.

Choosing Based on Adherence Profile

A practical way to think about the choice:

• Patients with demonstrated self-injection adherence on another biologic (e.g., adalimumab, semaglutide) are reasonable candidates for evolocumab's home-dosing model.
• Patients with a history of stopping oral or injectable medications within six months are better served by inclisiran's provider-administered structure.
• Patients in very high-risk ASCVD categories, two or more major ASCVD events, or one major event plus multiple high-risk conditions, should receive whichever PCSK9 inhibitor they will actually continue, because some LDL-C lowering sustained over years beats optimal LDL-C lowering abandoned at month four.

Side Effects and Safety

Both drugs carry a similar injection-site reaction profile. Across FOURIER, injection-site reactions occurred in 2.1% of evolocumab patients vs. 1.6% of placebo patients [1]. In ORION-10 and ORION-11, injection-site reactions were reported in 2.6% of inclisiran patients vs. 1.4% of placebo patients [2]. Neither drug has shown a clinically meaningful increase in liver enzyme elevation, muscle toxicity, or neurocognitive adverse events in randomized trial data.

Neurocognitive Concerns

Early pooled analyses raised a hypothesis that PCSK9 inhibition might affect neurocognitive function, given PCSK9's role in synaptic plasticity. The EBBINGHAUS sub-study of FOURIER (N=1,204) found no difference in neurocognitive function between evolocumab and placebo over a median of 19 months, using the Cambridge Neuropsychological Test Automated Battery. Inclisiran's trials did not show a neurocognitive signal either, though the follow-up duration in ORION-10 and ORION-11 was limited to 18 months.

Renal and Hepatic Considerations

Neither drug requires dose adjustment for mild to moderate renal impairment. Evolocumab's prescribing label notes no dedicated pharmacokinetic studies in severe renal impairment (eGFR <30 mL/min/1.73 m²), though the monoclonal antibody is unlikely to accumulate given its catabolism pathway. Inclisiran's GalNAc conjugate is taken up almost exclusively by hepatocytes; patients with severe hepatic impairment (Child-Pugh C) were excluded from ORION trials, so data are limited in that subgroup. The inclisiran prescribing information advises against use in severe hepatic impairment.

Cost, Prior Authorization, and Access

Both drugs carry list prices above $6,000 per year in the U.S., with evolocumab's list price approximately $5,800, $6,400 annually and inclisiran's approximately $3,250 per dose (roughly $6,500 annually after the two-dose induction phase).

Prior authorization requirements are substantial for both. A 2021 analysis in Circulation found that prior authorization denials for PCSK9 inhibitors were reversed on appeal in 56% of cases, suggesting that persistence through the appeals process meaningfully improves patient access. Manufacturer copay assistance programs (Amgen's Repatha SupportPlus, Novartis's Leqvio support program) can reduce out-of-pocket costs to near zero for commercially insured patients who qualify.

Medicare Part B covers inclisiran as a provider-administered drug, which may reduce cost-sharing compared to Part D for evolocumab in some Medicare beneficiaries. That difference alone leads some cardiologists to prefer inclisiran in their Medicare patient panels.

Switching Between Repatha and Leqvio

No published randomized trial has directly tested a structured switch protocol between evolocumab and inclisiran. The guidance below is based on each drug's pharmacokinetics, the prescribing labels, and expert consensus, and should be discussed with a prescribing physician before implementation.

Switching FROM Evolocumab TO Inclisiran

Evolocumab's half-life is approximately 11 to 17 days. After stopping evolocumab, PCSK9 protein levels begin recovering within two to three weeks, and LDL-C starts rising back toward baseline over four to eight weeks. The practical approach endorsed informally by lipid specialists is to administer the first inclisiran dose at the time the next evolocumab injection would have been due, no formal washout is required. This minimizes the window of uncontrolled LDL-C. Because inclisiran takes approximately 30 days to achieve its full nadir effect after the day-1 dose, the transition window carries some LDL-C rise, typically 10 to 15 mg/dL above evolocumab's nadir, before inclisiran reaches its steady-state effect. The ORION-3 open-label extension showed that patients previously on evolocumab who transitioned to inclisiran maintained LDL-C reductions of approximately 44% from original baseline at one year.

Switching FROM Inclisiran TO Evolocumab

This direction is less common but arises when a patient needs home self-injection capability (e.g., travel, office-visit access issues) or when their insurer switches formulary tier status. Inclisiran's silencing effect persists for approximately five to six months after a dose. Starting evolocumab before inclisiran's effect has fully waned means both mechanisms are active simultaneously. That overlap is not dangerous, both drugs lower LDL-C through the same downstream receptor pathway, but it does mean LDL-C may fall more than expected during the overlap period. Physicians should check a lipid panel four to six weeks after starting evolocumab in this scenario. Once inclisiran's effect has waned (roughly six months post-last-dose), evolocumab operates on its own normal pharmacokinetics.

When a Switch Is Warranted

Common clinical triggers for switching:

• Payer formulary change making one drug non-preferred
• Patient relocation removing access to a provider-administered injection site (favors switch to evolocumab)
• Demonstrated non-adherence with biweekly self-injection (favors switch to inclisiran)
• Pregnancy planning (both are Pregnancy Category not established; switch decisions are individualized)
• LDL-C goal not met, though in this scenario, investigating statin dose, ezetimibe addition, and medication adherence should precede a switch between two agents with similar LDL-C lowering magnitude

No published evidence supports the idea that one drug lowers LDL-C meaningfully more than the other in head-to-head conditions. The approximately 9-percentage-point difference in LDL-C reduction seen in cross-trial comparisons (59% for evolocumab in FOURIER vs. 50 to 52% for inclisiran in ORION-10/11) reflects different trial populations, different baseline LDL-C levels, and different statin use at baseline, not proven pharmacological superiority of evolocumab [1][2].

Which Patients Should Get Which Drug: A Clinical Summary

Evolocumab Is Preferred When:

• Proven MACE reduction is the primary clinical goal and the patient cannot wait for ORION-4 data
• The patient has a reliable self-injection history with another biologic
• Rapid LDL-C lowering is needed (acute post-ACS initiation, for example, where effect within days matters)
• Medicare Part D coverage is more favorable than Part B for that patient

Inclisiran Is Preferred When:

• Adherence history with self-injectables is poor
• The patient attends regular cardiology follow-up and fits injections into visit schedule
• Medicare Part B coverage reduces cost-sharing significantly
• The prescriber wants to eliminate biweekly injection burden for a patient already managing multiple chronic disease injectables

Neither drug replaces maximally tolerated statin therapy plus ezetimibe. Both drugs are add-on agents, not monotherapy substitutes. The 2022 ACC Expert Consensus Decision Pathway on PCSK9 inhibitor use is explicit: statin and ezetimibe should be optimized before a PCSK9 inhibitor is added.