HRS-5346 – Oral Lp(a) Inhibitor Phase II Study Shows Up to 86.3% Reduction at ESC 2026

An oral small-molecule Lp(a) inhibitor demonstrates dose-dependent Lp(a) reduction of up to 86.3% in Phase II study presented as a Late-Breaking Abstract at ESC 2026.

Introduction: The Lp(a) Challenge

Lipoprotein(a) — Lp(a) — is a highly atherogenic lipoprotein that has emerged as a significant independent risk factor for cardiovascular disease. Elevated Lp(a) levels are estimated to affect 20–30% of the global population and are associated with increased risk of myocardial infarction, stroke, and aortic stenosis.

Unlike LDL cholesterol, which can be effectively lowered by statins and PCSK9 inhibitors, Lp(a) has proven remarkably resistant to pharmacological intervention. No approved therapy specifically targets Lp(a), and lifestyle modifications have minimal impact on circulating Lp(a) levels.

At the European Society of Cardiology (ESC) 2026 Congress, investigators presented the Phase II results of HRS-5346 — an oral small-molecule Lp(a) inhibitor developed by Jiangsu Hengrui Medicine — demonstrating dose-dependent Lp(a) reduction of up to 86.3%.

HRS-5346: Mechanism of Action

HRS-5346 is a first-in-class oral small-molecule that specifically targets the Lp(a) assembly process. The compound is designed to bind to apolipoprotein(a) (apo(a)) and prevent its covalent linkage to apolipoprotein B-100, thereby inhibiting the formation of mature Lp(a) particles in the liver.

Key features include:

• Oral bioavailability — once-daily oral administration, patient-friendly dosing
• Dose-dependent efficacy — predictable Lp(a) lowering with dose escalation
• Minimal off-target effects — no significant impact on other lipid parameters or coagulation factors

Phase II Study Design

The Phase II study was a randomized, double-blind, placebo-controlled, dose-ranging trial conducted at multiple centers in China.

Parameter	Details
Number of patients	120 patients with elevated Lp(a) (≥75 nmol/L)
Dosing	Oral once daily for 12 weeks
Dose cohorts	Placebo, 10 mg, 40 mg, 80 mg, and 160 mg
Primary endpoint	Percent change in Lp(a) from baseline to week 12
Secondary endpoints	Safety, tolerability, pharmacokinetics

Key Results

Efficacy: Dose-Dependent Lp(a) Reduction

Dose	Mean Lp(a) Reduction (Week 12)
10 mg	42.1%
40 mg	61.8%
80 mg	74.5%
160 mg	86.3%

The 86.3% reduction in the 160 mg cohort represents the most potent Lp(a) lowering reported to date for any oral therapeutic agent.

Safety and Tolerability

• No dose-limiting toxicity — adverse events were mild to moderate in severity
• No significant laboratory abnormalities — no hepatotoxicity, no coagulopathy
• No dose-related safety signals — the highest dose was well-tolerated
• Discontinuation rate — comparable to placebo

Significance and Clinical Implications

The Phase II results of HRS-5346 have several important implications:

• First oral Lp(a)-specific therapy — offers a convenient alternative to injectable therapies in development
• Substantial Lp(a) reduction — 86.3% exceeds the threshold expected to deliver cardiovascular benefit
• Favorable safety profile — supports continued clinical development into Phase III
• Addressing residual cardiovascular risk — Lp(a) remains a major contributor to cardiovascular events in patients already on statin therapy

Comparison with Other Lp(a)-Targeting Approaches

Agent	Type	Lp(a) Reduction	Route
HRS-5346	Small molecule	Up to 86%	Oral
Pelacarsen (ASO)	Antisense oligonucleotide	~80%	Subcutaneous
Olpasiran (siRNA)	siRNA	~90%	Subcutaneous

HRS-5346 offers the advantage of oral administration compared to injectable ASO and siRNA therapies, potentially improving patient adherence.