Background: Anticoagulants are routinely used by millions of patients worldwide to prevent blood clots. Yet, problems with anticoagulant therapy remain, including a persistent and cumulative bleeding risk in patients undergoing prolonged anticoagulation. New safer anticoagulant targets are needed. Methods: We performed two-sample Mendelian randomization (MR) and genetic colocalization to prioritize anticoagulant targets with the strongest efficacy (venous thromboembolism [VTE] prevention) and safety (low bleeding risk) profiles. We leveraged three large-scale plasma protein datasets (deCODE, n=35,559; Fenland n = 10,708; ARIC n= 7,213) and one liver gene expression dataset (n =246) to evaluate evidence for a causal effect of 26 coagulation cascade plasma proteins on VTE from a new genome-wide association meta-analysis of 44,232 VTE cases and 847,152 controls (from the UK Biobank, FinnGen and Estonian Biobank), stroke subtypes (from UK Biobank and International Stroke Genetics consortium 73,652 cases and 1,234,808 controls), bleeding outcomes (FinnGen, n=309,154) and over one million parental lifespans (UK Biobank and LifeGen consortium). Results: Genetically predicted reductions in F2 blood levels were associated with lower VTE risk (OR [odds ratio] per 1 standard deviation [SD] lower F2=0.44, 95% CI=0.38-0.51, p=2.6E-28) and cardioembolic stroke risk (OR = 0.55, 95% CI=0.39-0.76, p=4.2e-04) but not with bleeding (OR = 1.13, 95% CI=0.93-1.36, p=2.2e-01). Genetically predicted F11 reduction were associated with lower risk of VTE (OR = 0.61, 95% CI=0.58-0.64, p=4.1e-85) and cardioembolic stroke (OR = 0.77, 95% CI=0.69-0.86, p=4.1e-06), but not with bleeding (OR = 1.01, 95% CI=0.95-1.08, p=7.5e-01) (Figure 3). These MR associations were concordant across the three blood protein datasets and the hepatic gene expression dataset as well as three different MR and colocalization analyses. Conclusion: These results provide strong genetic evidence that F2 and F11 may represent safe and efficacious therapeutic targets to prevent VTE and cardioembolic strokes without substantially increasing bleeding risk.

BJA is a consultant for Eli Lilly, Silence Therapeutics, Editas Medicine and Novartis and has received research contracts from Pfizer, Ionis Pharmaceuticals, Eli Lilly and Silence Therapeutics. AT receives research funding from Johnson & Johnson, Medtronic, and G.I. windows for studies related to bariatric surgery as well as consulting fees from Bausch Health and Novo Nordisk. The remaining authors disclose no conflicts

We would like to thank all study participants as well as all investigators of the studies that were used throughout the course of this investigation. EG holds a doctoral research award from the Fonds de recherche du Québec: Santé (FRQS). JB both hold a master research award from the FRQS. BJA holds a senior scholar award from the FRQS. MCV is Canada Research Chair in Genomics Applied to Nutrition and Metabolic Health.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

This research project has been approved by the ethical committee of the Quebec Heart and Lung institute.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

The GWAS summary statistics for VTE will be deposited on the GWAS catalog upon acceptation of the manuscript. All other genome-wide summary statistics used in this study are in the public domain.