Questions and Answers

The Redwood Study is a phase 3 clinical research study evaluating whether an investigational drug called fazirsiran can reduce liver scarring (fibrosis) in adults with Alpha-1 Antitrypsin Deficiency–associated liver disease. The study is being conducted at more than 80 research sites across 19 countries and is sponsored by Takeda.

Phase 3 means the drug has already been tested in earlier studies for safety and early signs of effectiveness and is now being evaluated in a larger group of participants to confirm those findings.

Fazirsiran is an investigational drug designed to reduce the production of the abnormal Z-AAT protein in the liver. It uses RNA interference (RNAi), a natural process that already exists in cells to regulate and "dial down" certain proteins, by targeting the genetic instructions that tell liver cells to produce this protein.

Fazirsiran has not been reviewed by any regulatory authority and is currently being studied to determine whether it is safe and effective.

When a drug is described as “investigational,” it means it has not yet been reviewed by a regulatory authority (such as the FDA in the United States or the EMA in Europe) for the treatment of any condition. The drug is still being studied in clinical research to determine whether it is safe and effective. Participating in a study like The Redwood Study is one of the ways this evaluation happens.

A placebo is a substance that looks the same as the investigational study drug but does not contain any active medication. In The Redwood Study, the placebo injection is designed to be indistinguishable from the fazirsiran injection. Using a placebo allows researchers to accurately measure any effects of the investigational study drug by comparing results between the two groups.

In a double-blind study, neither you nor your study doctor knows whether you are receiving the investigational study drug or the placebo. This design helps eliminate bias and ensures that the results reflect the true effects of the drug. The information is tracked securely and can be revealed if needed for your safety.

The study is looking for adults between the ages of 18 and 75 who have the PiZZ genotype of Alpha-1 Antitrypsin Deficiency and evidence of liver fibrosis. There are additional criteria that the research site will evaluate during the screening process.

If you are unsure whether you meet the criteria, taking the prescreener can be a helpful first step.

Not necessarily. If you know you have Alpha-1 Antitrypsin Deficiency but are not sure of your specific genotype, the research site can help confirm it through testing during the screening period. The study requires the PiZZ genotype, but you do not need to have this information before reaching out.

It means that participants are assigned to a treatment group by chance, similar to flipping a coin. In The Redwood Study, you will be randomly assigned to receive either fazirsiran or a placebo. This process is managed by a computer and helps ensure that the groups are balanced, which strengthens the reliability of the study results.

You will be randomly assigned to one of the treatment groups. There is a chance you will receive fazirsiran and a chance you will receive the placebo. The specific probability depends on the study design, and the research team can provide more detail about the randomization ratio during the informed consent process.

The total duration of participation is approximately four and a half years. This includes a screening period of up to 10 weeks, a treatment period of up to four years, and a follow-up period of up to six months. Your research team will walk you through the timeline and what to expect at each stage.

During the treatment period, there can be up to 20 in-person study visits at the research site. The frequency of visits varies throughout the study, with more frequent visits early on and fewer as the study progresses. Your study team will provide a detailed visit schedule.

During the first year of the treatment period, the research team may conduct monthly phone check-ins between study visits. These calls are intended to see how you are doing, ask about any symptoms or side effects, and answer any questions you may have. They are a way for the team to stay connected with you and monitor your well-being between in-person visits.

No. All study-related tests, procedures, and the investigational study drug itself are provided at no cost to you. This includes blood tests, liver biopsies, imaging, and other assessments required by the study protocol. Costs associated with your standard medical care outside of the study are not covered.

As with any investigational drug, there may be side effects associated with fazirsiran. The specific risks and potential side effects will be thoroughly discussed with you as part of the informed consent process before you begin the study.

The research team will monitor you closely throughout the study to identify and manage any side effects that may occur.

Your safety is monitored through regular blood tests, imaging, physical exams, vital sign checks, and other assessments throughout the study. An independent committee also reviews safety data on an ongoing basis to ensure the study is being conducted safely for all participants.

If you experience any symptoms or feel unwell at any time during the study, you should contact your research site right away. The study team will provide you with contact information for reaching them between visits, including for urgent situations. Do not wait until your next scheduled visit if you have concerns about your health.

Yes. Participation in The Redwood Study is entirely voluntary. You may choose to leave the study at any time and for any reason, without affecting your regular medical care. If you decide to stop participating, the research team may ask if you would be willing to complete an end-of-study visit for safety monitoring purposes, but this is not required.

Support for travel and time may be available, depending on the research site and local regulations. This can include reimbursement for transportation, parking, or other study-related expenses. The research site will be able to provide details about what support is available in your area.

The Redwood Study is being conducted at more than 80 research sites in 19 countries worldwide, including the United States, Canada, Australia, Brazil, and numerous countries across Europe. You can use the site finder on this page to search for a research site near you.

After you complete the prescreener, your responses will be reviewed to see if you might be a potential match for the study. If so, a research site near you will reach out, typically within a few business days, to discuss the study in more detail and schedule an initial conversation. There is no commitment involved in submitting your information.

If you have questions about the study, the best resource is a research site near you. The study team at each site includes doctors, nurses, and study coordinators who are knowledgeable about the study and can answer your specific questions. You can use the site finder on this page to locate a site and its contact information.