How Does Leqvio Work? Mechanism of Action Explained in Plain English

Leqvio (inclisiran) belongs to a class of medicines that didn't exist in clinical practice until very recently — small interfering RNA (siRNA) therapeutics. The science behind it is genuinely fascinating, and understanding it can help you appreciate why this medication works so differently from a statin or a traditional cholesterol pill. Here's the plain-English version.

Start With the Problem: Why LDL Cholesterol Gets Too High

LDL cholesterol (the "bad" kind) builds up in your blood and leads to plaques in your arteries — the root cause of heart attacks and strokes. Your liver is the main organ responsible for clearing LDL from your blood, and it does this through special docking points on liver cells called LDL receptors.

Here's where the problem comes in: there's a protein called PCSK9 (proprotein convertase subtilisin/kexin type 9) that acts like a wrecking ball. PCSK9 binds to LDL receptors on liver cells and destroys them. Fewer receptors means less LDL is cleared from the blood — and cholesterol levels rise.

The Role of PCSK9 — and Why Blocking It Lowers Cholesterol

People with naturally low PCSK9 activity have been found to have very low LDL levels and an extremely low risk of heart disease. This discovery, made in the early 2000s, sparked a wave of drug development targeting PCSK9. The first drugs to come out of this were monoclonal antibody injections (Repatha and Praluent) that block PCSK9 after it's been made. Leqvio takes a completely different approach.

How RNA Interference Works: Targeting PCSK9 at the Source

Every protein your body makes starts with a genetic instruction written in DNA. When your cells need to make a protein, they create a temporary copy of the DNA instruction called messenger RNA (mRNA). This mRNA travels out of the nucleus and acts as the blueprint for making the protein.

Leqvio (inclisiran) is designed to intercept and destroy the specific mRNA that carries the instructions for making PCSK9. No mRNA blueprint = no PCSK9 protein produced. No PCSK9 = LDL receptors stay intact = more LDL cleared from your blood.

This process — using small RNA molecules to interfere with gene expression — is called RNA interference (RNAi). The Nobel Prize in Physiology or Medicine was awarded for the discovery of RNA interference in 2006, reflecting how groundbreaking this science is.

How Does Leqvio Get Into Liver Cells?

Getting RNA molecules into the right cells is technically challenging. Leqvio solves this cleverly. The inclisiran molecule is conjugated (attached) to a compound called GalNAc (triantennary N-acetylgalactosamine). Liver cells have special receptors (ASGPR) that actively grab and import GalNAc-tagged molecules. This means Leqvio selectively enters liver cells, exactly where the PCSK9 mRNA needs to be targeted.

Once inside the liver cell, inclisiran loads into a protein complex called RISC (RNA-Induced Silencing Complex), which then seeks out and catalytically destroys the PCSK9 mRNA. Because this process is catalytic (one RISC complex can destroy many mRNA copies), the effects are sustained long after the drug has cleared from plasma.

Why Does Leqvio Last 6 Months?

This is the key pharmacological advantage of Leqvio over PCSK9 monoclonal antibodies. Monoclonal antibodies like Repatha and Praluent work by blocking PCSK9 in the bloodstream after it's made. PCSK9 keeps being produced, so the antibody has to be re-administered every 2–4 weeks to maintain blockade.

Leqvio stops PCSK9 from being made at all. Once RISC is loaded with inclisiran inside a liver cell, it continues silencing PCSK9 mRNA for months. This is why a single injection maintains LDL-C reduction for approximately 6 months, allowing for the remarkable twice-yearly dosing schedule.

What Happens to LDL-C After Leqvio?

After a single 284 mg injection of Leqvio, LDL-C reduction is detectable within 14 days. Mean LDL-C reductions of 38–51% are observed between Days 30–180 following each dose. At Day 180 (the 6-month mark), LDL-C levels are still reduced by approximately 53% — demonstrating how durable the effect is.

PCSK9 levels in the blood are also reduced — by approximately 75% at Day 120 after two doses. Less PCSK9 means more active LDL receptors, and more LDL receptors means more cholesterol is cleared.

Does Leqvio Affect DNA?

No. Leqvio works on messenger RNA (mRNA), which is a temporary copy of genetic instructions, not on DNA itself. It does not alter your genes, does not integrate into your genome, and does not cause any permanent genetic changes. This is an important distinction from gene therapy, which modifies DNA directly.

For a broader overview of Leqvio including dosage and uses, read our guide: What Is Leqvio?.

Curious about side effects? Read Leqvio side effects: what to expect.