Inclisiran Cardiovascular Outcomes Trials
The effect of inclisiran on cardiovascular morbidity and mortality has not yet been definitively established, as the two major cardiovascular outcomes trials—ORION-4 and VICTORION-2 PREVENT—are still ongoing with results expected in 2026-2029. 1
Current Evidence Status
Completed Phase III Trials (LDL-C Reduction Only)
The ORION-9, -10, and -11 trials demonstrated robust LDL-C lowering efficacy but were not designed as cardiovascular outcomes trials. These studies showed:
- Mean placebo-corrected LDL-C reduction of 50.7% at day 510 1
- Pooled analysis of 3,660 patients over 18 months
- Primary endpoint was LDL-C reduction, not cardiovascular events
Exploratory Cardiovascular Event Analysis
A post-hoc patient-level analysis of the Phase III trials provided early signals but cannot be considered definitive evidence:
- Inclisiran significantly reduced composite MACE with OR 0.74 (95% CI: 0.58-0.94) 2
- However, no significant reduction in fatal/non-fatal MI (OR 0.80,95% CI: 0.50-1.27) or stroke (OR 0.86,95% CI: 0.41-1.81) 2
- These were non-adjudicated events collected as safety data, not primary outcomes
- Follow-up was only 18 months—insufficient duration for robust cardiovascular outcomes assessment
Ongoing Cardiovascular Outcomes Trials
ORION-4 Trial Design 1
- Population: ~15,000 participants aged ≥55 years with pre-existing ASCVD and LDL-C ≥100 mg/dL on maximally tolerated statin therapy
- Sites: 180 clinical sites in UK and United States
- Intervention: Inclisiran 300 mg vs placebo subcutaneously at baseline, 3 months, then every 6 months
- Duration: Median 5 years
- Primary endpoint: Composite of coronary heart disease death, nonfatal MI, fatal/nonfatal ischemic stroke, or urgent coronary revascularization
- Expected results: 2026 (recruitment completed September 2023)
VICTORION-2 PREVENT Trial Design 1, 3
- Population: ~15,000 participants aged ≥40 years with established ASCVD on high-intensity statin therapy (±ezetimibe) with LDL-C ≥70 mg/dL
- Sites: United States, Canada, and Europe
- Primary endpoint: 3-point MACE (CV death, nonfatal MI, nonfatal ischemic stroke)
- Expected completion: October 2027
VICTORION-1 Trial 4
- Expected completion: April 2029
- Limited design details provided in available evidence
Critical Clinical Implications
The FDA label explicitly states: "The effect of inclisiran on cardiovascular morbidity and mortality has not been determined." 5
This is a crucial distinction from PCSK9 monoclonal antibodies (evolocumab and alirocumab), which have demonstrated cardiovascular outcomes benefits in dedicated trials (FOURIER and ODYSSEY OUTCOMES).
Current Clinical Use
Despite lack of outcomes data, inclisiran received FDA approval in December 2021 based on:
- Robust LDL-C lowering efficacy (~50% reduction) 1
- Favorable safety profile comparable to placebo 1
- Unique twice-yearly dosing after initial loading (Day 1, Day 90, then every 6 months)
Important Caveats
- LDL-C reduction ≠ proven cardiovascular benefit: While LDL-C lowering is an established surrogate marker, only dedicated outcomes trials can definitively prove mortality/morbidity benefits
- Comparison to PCSK9 mAbs: Inclisiran appears to produce approximately 10% less LDL-C reduction than PCSK9 monoclonal antibodies in similarly designed trials 1
- Duration of follow-up matters: The 18-month exploratory analysis is insufficient—cardiovascular benefits typically require 2-5 years to manifest robustly
Bottom Line for Clinical Practice
Until ORION-4 and VICTORION-2 PREVENT results are available, inclisiran should be prescribed primarily for its proven LDL-C lowering efficacy, not for assumed cardiovascular outcomes benefits. The twice-yearly dosing offers a significant adherence advantage, particularly valuable in patients with documented statin non-adherence. However, for patients requiring immediate proven cardiovascular risk reduction, PCSK9 monoclonal antibodies with established outcomes data may be preferred despite more frequent dosing requirements.