RecruitingPHASE3INTERVENTIONAL

A Study to Learn About the Study Medicine Ibuzatrelvir in Adults With COVID-19 Who Are Severely Immunocompromised

This study aims to discover if a new medicine, ibuzatrelvir, can help adults with a weakened immune system fight off COVID-19. People with weaker immune systems often struggle more with infections. The study will compare whether ibuzatrelvir, either by itself or combined with another drug called remdesivir, is more effective and safer than remdesivir alone. Participants will be adults who have COVID-19 symptoms, have a weakened immune system due to conditions like certain cancers or organ transplants, and are not so unwell that they need extra oxygen. Taking part will involve several visits over about 24 weeks for check-ups, blood tests, and nose swabs to see how the treatments are working.

At a glance

Status

Recruiting

Phase

PHASE3

Sponsor

Pfizer

Enrolment target

300

Start

14 Jul 2025

Estimated completion

25 Feb 2028

COVID-19 Infection

What is this study about?

This important study is investigating new ways to treat COVID-19, specifically for adults who have a weakened immune system. You might have a weakened immune system if you have certain health conditions like blood cancer, have had an organ transplant, or are taking specific medications. People with weakened immune systems can find it harder to fight off infections like COVID-19, and they might stay ill for longer or become more seriously unwell.

The main goal of this study is to test a new medicine called ibuzatrelvir. We want to find out if it is safe and effective when used to treat COVID-19 in this group of patients. We'll be looking to see if ibuzatrelvir, either on its own or when combined with another treatment called remdesivir, works better than just using remdesivir by itself. All treatments in this study are given to help fight COVID-19.

By comparing these different treatment approaches, the study hopes to find the best way to help adults with weakened immune systems recover from COVID-19. This could potentially lead to better care and outcomes for many people who are at higher risk from the virus.

Key takeaways

The study tests new COVID-19 treatments for people with weakened immune systems.
It compares ibuzatrelvir (new drug) with or without remdesivir (existing drug).
Participation involves about 10 clinic visits over 24 weeks.
You must have a weakened immune system and current COVID-19 symptoms (not needing oxygen).
All participants receive active COVID-19 treatment; no one receives only a dummy drug.
Your health will be closely monitored, and you can withdraw at any time.

Who may be eligible?

This study is looking for adults aged 18 or over who have had a clear diagnosis of COVID-19 within the last two days and started showing symptoms within the last five days. You must also still be experiencing at least one symptom on the day you join the study. A key part of who can join is having a severely weakened immune system. This could be due to having a solid organ transplant and taking medicines to prevent rejection, having certain blood cancers (like some types of leukaemia or lymphoma), or if you've recently had specific cell therapies or treatments that affect your immune cells.

However, some people won't be able to join. You can't participate if your COVID-19 is very severe, or if you need extra oxygen because of the virus. Also, those with severe kidney or liver problems, or anyone who has had a bad reaction to similar medicines in the past, cannot take part. If you have another serious infection or a life expectancy of less than 30 days due to another condition, you won't be eligible. The study team will check your full medical history to make sure it's safe for you to participate.

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 18 years old or older?
Have you recently tested positive for COVID-19 and still have symptoms?
Do you have a weakened immune system (e.g., from cancer, transplant, specific medicines)?
Are you NOT currently needing extra oxygen for your COVID-19?
Do you NOT have severe kidney or liver disease?

Answer every question to see your result.

What does participation involve?

If you decide to join this study, your participation will last for about 24 weeks (roughly 6 months). You will have about 10 visits to the study clinic during this time.

For the treatments, you will be assigned by chance to one of three groups. One group will receive only remdesivir, which is given into a vein (IV). Another group will get ibuzatrelvir, taken as a tablet by mouth twice a day. The third group will receive both ibuzatrelvir and remdesivir. To make sure the comparisons are fair, some treatments will also include 'placebos', which look like the actual medicines but contain no active drug. This means everyone will follow the same routine, but what medicine they actually receive will differ.

During your visits, you'll have regular health check-ups, blood tests, and swabs taken from your nose. You might also be asked to do some nose swabs at home yourself. You will also fill out some questionnaires about how you are feeling. The information gathered from these visits and tests will help the doctors understand if the new treatments are safe and working, and help decide if they should be made available to more people.

Potential risks and benefits

Taking part in any medical study has potential benefits and risks. A potential benefit of this study is that you might receive a new treatment (ibuzatrelvir) that could be more effective for your COVID-19, especially with your weakened immune system. All participants will receive an active COVID-19 treatment. However, there's no guarantee that the treatment will work for you, or that it will be better than standard care. Potential risks could include side effects from the study medicines, discomfort from blood tests or nose swabs, or inconvenience from the study visits. Your health will be carefully monitored throughout the study. You are free to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (141)

Hope Clinical Research, Inc.
Verified postcode
Canoga Park, United States· Recruiting
Amicis Research Center - Granada Hills
Verified postcode
Granada Hills, United States· Recruiting
Jacobs Medical Center at UC San Diego Health
Verified postcode
La Jolla, United States· Recruiting
UC Davis CTSC Clinical Research Center
Verified postcode
Sacramento, United States· Recruiting
University of California Davis Health
Verified postcode
Sacramento, United States· Recruiting
UC San Diego Medical Center - Hillcrest
Verified postcode
San Diego, United States· Recruiting
University of California San Diego Health
Verified postcode
San Diego, United States· Recruiting
UCHealth Anschutz Inpatient Pavilion - Anschutz Medical Campus
Verified postcode
Aurora, United States· Recruiting
University of Colorado Anschutz Medical Campus
Verified postcode
Aurora, United States· Recruiting
University of Colorado Clinical and Translational Research Center
Verified postcode
Aurora, United States· Recruiting
University of Colorado Hospital
Verified postcode
Aurora, United States· Recruiting
Georgetown University Medical Center
Verified postcode
Washington D.C., United States· Recruiting

Common questions

What is ibuzatrelvir?

Ibuzatrelvir is a new medicine being tested in this study to see if it can help treat COVID-19, especially in people with weakened immune systems.

What is a 'weakened immune system'?

It means your body's natural defense against infections isn't as strong as usual, often due to conditions like certain cancers, organ transplants, or some medications.

Will I get a 'dummy' pill?

To ensure accurate results, some participants receive placebo pills or infusions that look like the study medicines but contain no active drug. This helps us compare the real effects of the active medicines.

How long will the study last for me?

If you join, your involvement in the study will be for about 24 weeks, which is roughly six months.

Will my regular doctor know I'm in the study?

Yes, it's very important to keep your regular doctor informed about all your medical care, including participating in a study. The study team can help with this.

How to find out more

Pfizer CT.gov Call Center

clinicaltrials.gov_inquiries@pfizer.com 1-800-718-1021 Official trial record

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