A Single Ascending Dose Study to Assess the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of CITY-FXI in Healthy Adults and Adults With FV Leiden or Prothrombin G20210A Mutation

A Phase 1, Randomised, Double-Blind, Placebo-Controlled Single Ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of CITY-FXI, a FXI Targeting siRNA, Administered Subcutaneously in Healthy Adults and Adults With Factor V Leiden or Prothrombin G20210A Mutation

This is a first-in-human (FIH), single-center, randomised, double-blind, placebo-controlled, single ascending dose (SAD) study evaluating the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of CITY-FXI in healthy adults and adults with Factor V Leiden (FVL) or prothrombin G20210A mutation.

The study will be conducted in two parts:

• Part A: Single Ascending Dose in Healthy Adults
• Part B: Single Ascending Dose in Adults with Factor V Leiden (FVL) or Prothrombin G20210A Mutation

Inclusion Criteria:

• Males and women of non-childbearing potential (WONCBP) aged 18 to 45 years (Part A only)
• Male and female participants aged 18 to 60 (Part B only)
• Body Mass Index (BMI) between 18 and 25 kg/m2 (inclusive) and a minimum weight of 50 kg
• Ability and willingness to comply fully with all study procedures and lifestyle considerations
• Confirmed diagnosis of FVL or prothrombin G20210A mutation via genetic testing (Part B only)
• Women of childbearing potential (WOCBP) must agree to use acceptable highly effective contraceptive methods (Part B only)

Exclusion Criteria:

• Any clinically significant systemic disease or disorder, including but not limited to cardiovascular, hepatic, or oncological conditions
• History or evidence of any bleeding disorders
• History of clinically significant spontaneous bleeding
• Prior treatment with an investigational agent
• Confirmed diagnosis of homozygous mutations, or combined thrombophilic defects of (Part B only)