RecruitingPHASE1INTERVENTIONAL

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

This study is looking into a new medicine called CITY-FXI for the very first time in people. We want to see if it's safe and how the body handles it. It's being tested in two groups: healthy adults and adults who have a higher risk of blood clots due to conditions called Factor V Leiden or Prothrombin G20210A mutation. Participants will be given either the new medicine or a dummy medicine (placebo). This is a 'Phase 1' study, which means it's an early step to understand the medicine before larger studies can happen. The main goal is to check for side effects and how the medicine works in the body.

At a glance

Status

Recruiting

Phase

PHASE1

Sponsor

City Therapeutics

Enrolment target

128

Start

22 Jan 2026

Estimated completion

01 Oct 2027

Factor V Leiden Prothrombin G20210A

What is this study about?

You might have heard of conditions like Factor V Leiden or Prothrombin G20210A mutation. These are genetic conditions that can make your blood clot more easily than usual, which can sometimes lead to serious health problems. Scientists are always looking for new ways to help manage these conditions and prevent complications.

This study is an important early step in testing a new medicine called CITY-FXI. Think of it like taking a brand new car for its first test drive – we want to make sure it's safe and see how it performs. The main aims are to understand if CITY-FXI is safe for people to take, how well the body tolerates it (meaning, how many side effects people experience), and how the medicine moves through and works in the body. This information is really important for deciding if the medicine should be tested further.

The study involves two main groups: healthy volunteers and people who have either Factor V Leiden or Prothrombin G20210A mutation. This allows researchers to compare how the medicine affects different people. By testing it in this way, we can learn more about its potential to help people with these specific genetic conditions in the future.

Key takeaways

This is an early-stage study testing a new medicine called CITY-FXI.
It aims to check if the medicine is safe and how our bodies react to it.
The study includes healthy adults and those with specific blood clotting conditions.
Participants will receive either the new medicine or a dummy medicine.
Your participation helps to advance medical knowledge for future treatments.
You can withdraw from the study at any time.

Who may be eligible?

To join this study, you need to be an adult between 18 and 60 years old. Your weight should be within a healthy range for your height (your Body Mass Index, or BMI, should be between 18 and 25 kg/m2) and you must weigh at least 50 kg.

For the group focusing on healthy adults, participants need to be between 18 and 45 years old. If you have Factor V Leiden or Prothrombin G20210A mutation, you must have had a genetic test to confirm this. Women who could become pregnant and are in the group with the genetic conditions must agree to use highly effective birth control throughout the study. Unfortunately, if you have a severe existing health condition, a bleeding disorder, or a history of significant unexpected bleeding, you wouldn't be able to join.

Also, if you have two copies of the Factor V Leiden or Prothrombin G20210A mutation (called homozygous) or have several blood clotting problems at once, you wouldn't be able to take part in the study that includes people with these conditions. If you've recently taken part in another clinical trial with a new medicine, you also won't be eligible for this study.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 18 and 60 years old?
Is your weight (BMI) within a healthy range (18-25) and do you weigh at least 50 kg?
Do you have Factor V Leiden or Prothrombin G20210A mutation (if applying for that group)?
Do you have any serious existing health problems or a history of bleeding disorders?
Are you willing and able to follow all study instructions and attend appointments?
Have you recently taken part in another study with a new medicine?

Answer every question to see your result.

What does participation involve?

If you decide to take part, you'll visit a single study centre. You'll either receive the new medicine, CITY-FXI, or a dummy medicine (placebo). Neither you nor the study team will know which you are receiving – this is called a 'double-blind' study. The study involves a single dose of the medicine. After taking the medicine, the study team will carefully monitor you. They will check your health, take blood samples, and ask about any side effects you might experience. This will help them understand how your body reacts to the medicine and how it works. The exact number of visits and the total length of your participation will be explained in detail by the study team, but it typically involves an initial screening, the day you receive the medicine, and several follow-up appointments.

Potential risks and benefits

Taking part in any research study has potential benefits and risks. While you might not directly benefit from receiving the study medicine, your participation is incredibly valuable. It helps researchers gather essential information that could lead to new treatments for people with blood clotting conditions in the future. Potential risks include side effects from the study medicine, which could be mild, like a headache, or more serious, though serious side effects are carefully monitored and rare in early-stage studies. There are also risks associated with study procedures, like blood draws. You have the right to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

Richmond Pharmacology
Verified postcode
London, United Kingdom· Recruiting

Common questions

What is a 'Phase 1' study?

Phase 1 studies are the first time a new medicine is given to people. They mainly check if the medicine is safe and how the body handles it.

What is a placebo?

A placebo is a dummy medicine, like a sugar pill or a saline injection, that looks like the real medicine but contains no active drug. It helps compare the effects of the actual medicine.

What are Factor V Leiden and Prothrombin G20210A?

These are genetic conditions that can make your blood clot more easily than usual, increasing the risk of blood clots.

Will I know if I'm getting the real medicine or the placebo?

No, this is a 'double-blind' study, meaning neither you nor the study team will know who is getting the real medicine until the study is over.

Is travel to the study site covered?

You should discuss any costs, including travel, with the study team before you agree to take part.

How to find out more

City Therapeutics

clinicaltrials@citytx.com 857-219-5440 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.