A Pilot Study to Investigate Platelet Reactivity in Patients With Elevated Lipoprotein(a) and Its Response to Antiplatelet Therapy (Lp(a)-PLAT)

A Pilot Study to Investigate Platelet Reactivity in Patients With Elevated Lipoprotein(a) and Its Response to Antiplatelet Therapy Randomised, Open-Label, Mechanistic Pilot Study With A Crossover Design

The Lp(a)-PLAT Study is designed to close a critical evidence gap in cardiovascular prevention for the roughly 20% of the population who carry genetically determined elevations in lipoprotein(a) - a recognised pro-thrombotic and pro-atherosclerotic risk factor. Its objective is to delineate the pro-thrombotic platelet phenotype driven by high Lp(a) levels and to evaluate, through pharmacodynamic comparison, how two standard-of-care antiplatelet strategies - clopidogrel, a P2Y12 ADP-receptor inhibitor, and aspirin, a COX-1 inhibitor - differ in their capacity to attenuate this platelet hyperreactivity.

This study will provide the first head-to-head mechanistic comparison of clopidogrel versus aspirin on platelet reactivity in patients with elevated plasma levels of Lp(a).

Study Overview

• Status: Not yet recruiting
• Conditions: Cardiovascular Prevention
• Intervention / Treatment: Drug: Aspirin; Drug: Clopidogrel

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Kapka Miteva, PhD; Phone Number: +41 22 379 4648; Email: Kapka.Miteva@unige.ch

Study Locations

• Switzerland
  • Geneva, Switzerland, 1205
    • Hopitaux Universitaires de Geneve
    • Contact: Véronique Menoni, PhD; Phone Number: +41 0223729195; Email: veronique.menoni@hug.ch
    • Principal Investigator: François Mach, Prof

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age ≥ 18 years at the time of informed consent.
• Ability to provide written informed consent in accordance with Swiss Human Research Act (HRA) and ICH-GCP.
• Documented plasma lipoprotein(a) [Lp(a)] concentration:

High Lp(a) cohort: ≥ 125 nmol/L (approximately ≥ 75th percentile) Low Lp(a) comparator cohort (if applicable): < 25-30 nmol/L

• Clinically stable at the time of inclusion, with no acute cardiovascular event within the previous 3 months.
• Willingness and ability to comply with all study procedures, including blood sampling and study medication intake.
• For women of childbearing potential: willingness to use adequate contraception during the study period (if applicable according to local ethics requirements).

Exclusion Criteria:

• Cardiovascular and bleeding-related conditions Active bleeding or known bleeding disorder. History of hemorrhagic stroke or intracranial hemorrhage. High risk of bleeding as judged by the investigator. Platelet count < 100 × 10⁹/L at screening. Known platelet function disorder.
• Contraindications to study medications Known hypersensitivity or contraindication to aspirin (acetylsalicylic acid) or clopidogrel.

History of aspirin-induced asthma, severe NSAID intolerance, or anaphylactic reaction to salicylates.

Active peptic ulcer disease or clinically significant gastrointestinal bleeding within the past 6 months.

- Concomitant medications and interference with platelet function Current use of dual antiplatelet therapy (DAPT), oral anticoagulants (e.g., DOACs, vitamin K antagonists), or other potent antithrombotic agents that cannot be safely interrupted.

Use of non-steroidal anti-inflammatory drugs (NSAIDs) within 7 days prior to study entry (unless discontinued per protocol).

Use of P2Y12 inhibitors or aspirin within an insufficient washout period. - Clinical conditions Severe hepatic impairment (ALT/AST > 3× ULN) or severe renal impairment (eGFR < 30 mL/min/1.73 m²).

Active malignancy requiring systemic chemotherapy. Known hematologic disorder affecting platelet function or coagulation. Acute infection or inflammatory condition likely to affect platelet function.

- Other exclusions Pregnancy or breastfeeding. Participation in another interventional clinical trial within the last 30 days or 5 half-lives of the investigational product, whichever is longer.

Any condition that, in the opinion of the investigator, would interfere with study participation, compliance, or interpretation of results.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Aspirin → Clopidogrel Sequence; Participants receive aspirin 100 mg once daily for 14 days, followed by a 14-day washout period, then clopidogrel 75 mg once daily for 14 days. Platelet function is assessed at baseline and after each treatment period.	Drug: Aspirin; Aspirin 100 mg administered orally once daily for 14 consecutive days during one treatment period of the randomized crossover study. Participants receive aspirin either during Period 1 or Period 2 depending on the randomized treatment sequence. A 14-day washout period separates the two treatment periods.; Drug: Clopidogrel; Clopidogrel 75 mg administered orally once daily for 14 consecutive days during one treatment period of the randomized crossover study. Participants receive clopidogrel either during Period 1 or Period 2 depending on the randomized treatment sequence. A 14-day washout period separates the two treatment periods.
Experimental: Clopidogrel → Aspirin Sequence; Participants receive clopidogrel 75 mg once daily for 14 days, followed by a 14-day washout period, then aspirin 100 mg once daily for 14 days. Platelet function is assessed at baseline and after each treatment period.	Drug: Aspirin; Aspirin 100 mg administered orally once daily for 14 consecutive days during one treatment period of the randomized crossover study. Participants receive aspirin either during Period 1 or Period 2 depending on the randomized treatment sequence. A 14-day washout period separates the two treatment periods.; Drug: Clopidogrel; Clopidogrel 75 mg administered orally once daily for 14 consecutive days during one treatment period of the randomized crossover study. Participants receive clopidogrel either during Period 1 or Period 2 depending on the randomized treatment sequence. A 14-day washout period separates the two treatment periods.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in collagen-induced platelet aggregation after aspirin versus clopidogrel treatment	Within-participant change from baseline in collagen-induced platelet aggregation measured by light transmission aggregometry (LTA) after 14 days of aspirin 100 mg once daily compared with 14 days of clopidogrel 75 mg once daily in the randomized crossover design.	Baseline and Day 14 of each treatment period (up to 42 days)
Change in soluble platelet activation biomarkers after aspirin versus clopidogrel treatment	Within-participant change from baseline in soluble platelet activation biomarkers (including soluble P-selectin/CD62P, soluble CD40 ligand [sCD40L], platelet factor 4 [PF4], and related biomarkers) following 14 days of aspirin 100 mg once daily compared with 14 days of clopidogrel 75 mg once daily.	Baseline and Day 14 of each treatment period (up to 42 days)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Agonist-specific platelet aggregation	Change from baseline in platelet aggregation measured by light transmission aggregometry following stimulation with arachidonic acid, ADP, and TRAP-6 after each treatment period.	Baseline and Day 14 of each treatment period (up to 42 days)
Platelet surface activation markers	Change from baseline in platelet surface expression of CD62P (P-selectin) and activated GPIIb/IIIa measured by flow cytometry following aspirin and clopidogrel treatment.	Baseline and Day 14 of each treatment period (up to 42 days)
Biochemical verification of aspirin pharmacodynamic effect	Serum thromboxane B2 (TxB2) concentration measured to verify cyclooxygenase-1 inhibition during aspirin treatment.	Day 14 of the aspirin treatment period
Biochemical verification of clopidogrel pharmacodynamic effect	Vasodilator-stimulated phosphoprotein (VASP) platelet reactivity index (PRI) measured to verify P2Y12 receptor inhibition during clopidogrel treatment.	Day 14 of the clopidogrel treatment period
Association between plasma lipoprotein(a) concentration and platelet function	Correlation between plasma lipoprotein(a) concentration and platelet function parameters measured by light transmission aggregometry, flow cytometry, and soluble biomarkers.	Baseline and Day 14 of each treatment period (up to 42 days)
Baseline comparison of platelet reactivity between participants with high and low lipoprotein(a)	Comparison of baseline platelet function parameters between participants with elevated lipoprotein(a) (>125 nmol/L) and matched participants with low lipoprotein(a) (<25 nmol/L).	Baseline (Day 0)
Plasma proteomic profile associated with lipoprotein(a) and antiplatelet therapy (Exploratory)	Exploratory analysis of plasma proteins measured using the Olink® proximity extension assay platform to identify proteins associated with elevated lipoprotein(a), platelet reactivity, and treatment with aspirin or clopidogrel.	Baseline and Day 14 of each treatment period (up to 42 days)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Identification of candidate biomarkers associated with lipoprotein(a)-related platelet hyperreactivity	Exploratory identification of circulating protein biomarkers associated with platelet hyperreactivity and pharmacodynamic response to aspirin and clopidogrel using Olink® proteomic analysis. Results are hypothesis-generating only.	Baseline and Day 14 of each treatment period (up to 42 days)

Collaborators and Investigators

• Sponsor: François MACH
• Collaborators: University Hospital, Geneva
• Investigators: Principal Investigator: François Mach, Prof, HUG

Study record dates

Study Major Dates

• Study Start (Estimated): November 1, 2026
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): November 1, 2027

Study Registration Dates

• First Submitted: July 17, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 17, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Lipoprotein(a)
• Additional Relevant MeSH Terms: Sulfur Compounds; Organic Chemicals; Pyridines; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Hydrocarbons; Hydrocarbons, Cyclic; Hydrocarbons, Aromatic; Phenols; Benzene Derivatives; Thiophenes; Salicylates; Hydroxybenzoates; Ticlopidine; Thienopyridines; Clopidogrel; Aspirin
• Other Study ID Numbers: 2026-01415

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

IPD Plan Description

Individual participant data collected during the Lp(a)-PLAT study, including clinical data, laboratory results, and platelet function measurements, will not be shared in public data repositories.

Given the mechanistic nature of the study and the small sample size, there is a potential risk of indirect re-identification of participants even after standard anonymisation procedures. Therefore, raw participant-level datasets will remain under controlled access within the Sponsor institution (Hôpitaux Universitaires de Genève, HUG).

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No