Explore a New Path for Alpha-1 Liver Disease

The purpose of The Redwood Study is to evaluate the safety and effectiveness of an investigational study medicine, called TAK-999 (fazirsiran), in adults 18 to 75 years of age with Alpha-1 Antitrypsin Deficiency–Associated Liver Disease, also referred to as Alpha-1 Liver Disease or AATD Liver Disease.

The investigational study medication will be compared to placebo; both groups will receive injections, but the placebo contains no active medication. This study may help researchers understand whether TAK-999 can reduce liver scarring caused by Alpha-1 Liver Disease.

Find a participating research site

Who May Qualify

If you are between 18 and 75 years of age, and you or any of your family members have a confirmed or suspected diagnosis of Alpha-1 Liver Disease (AATD-LD with the PiZZ mutation), you may be eligible for this study. If interested, a participating research site can confirm a diagnosis of Alpha-1 Liver Disease, as well as other study criteria, to determine your/their eligibility.

About the Investigational Study Medication

There is currently no approved treatment available for Alpha-1 Liver Disease. The investigational study medicine, TAK-999, aims to reduce production of the abnormal Z-AAT protein and its build-up in the liver. The reduction in levels of the protein may result in a decrease in a decrease in liver scarring.

Researchers are investigating the safety and effectiveness of TAK-999 in adults with Alpha-1 Liver Disease. The investigational study medicine will be evaluated alongside the placebo to help researchers determine if TAK-999 may reduce liver scarring caused by Alpha-1 Liver Disease. The use of a placebo (contains no active medication) in this study will help the researchers by providing a group that does not receive medication to compare with a group that does.

There are two treatment groups in this study, with one group receiving the investigational study medicine and the other receiving the placebo. Each participant will be randomly assigned to one of the groups and will receive their assigned study treatment as an injection. During the treatment period, neither the participant nor the study doctor will know which group the participant is in, but in the case of an emergency, the study doctor can quickly find out.

Study Participation

Participation in The Redwood Study will last approximately four and a half years and consists of three periods:

Screening period

Lasts up to 10 weeks and consists of one or more study visits. During this period, the study team will perform tests and procedures to determine your eligibility for the study. The study team can confirm a diagnosis of Alpha-1 Liver Disease during this period.

Treatment period

Lasts up to four years and consists of up to 28 visits to the study site. Participants will be randomised to receive the investigational study medication or the placebo. Both the investigational study medication and the placebo are administered as injections.

Follow-up period

Participants will be followed for up to six months after their last dose of their study treatment for continued monitoring of their health.

Find a Participating Research Site

Enter your postcode to find the participating research site(s) nearest you.

About Alpha-1 Antitrypsin Deficiency–Associated Liver Disease

As you may know, Alpha-1 Antitrypsin Deficiency (AATD) is an inherited condition that can cause damage to the liver and/or affect the lungs.Footnote1 It is passed down from parents to their children. Liver disease associated with AATD (also known as Alpha-1 Liver DiseaseFootnote2) is caused by abnormal AAT protein building up in the liver.Footnote3 Not everyone who produces abnormal AAT protein develops Alpha-1 Liver Disease; but in those who do, the build-up of abnormal AAT triggers liver damage.Footnote3,Footnote4 This can lead to the development of fibrosis, which is the formation of scar tissue in the liver, and that may progress to cirrhosis, late stage of scarring of the liver, potentially necessitating a liver transplant.Footnote3,Footnote4,Footnote5,Footnote6

Currently, there is no approved treatment option for Alpha-1 Liver Disease.Footnote2

By taking part in a study that is evaluating an investigational study medicine designed to target the cause of Alpha-1 Liver Disease, participants in The Redwood Study could make a difference in the lives of others who have or may be diagnosed with Alpha-1 Liver Disease in the future.


  1. Brantly M, et al. Orphanet J Rare Dis 2020;15:96
  2. alpha1.org/newly-diagnosed/learning-about-alpha-1/liver-disease
  3. Piccolo P, et al. In: Strnad P, et al (eds). α1-Antitrypsin Deficiency (ERS) Monograph, 93–104. Sheffield: ERS, 2019.
  4. Patel D, et al., Clin Liver Dis 2018;22(4):643–655
  5. Liedtke C, et al. Front Med (Lausanne) 2022;8:814496.
  6. nejm.org/doi/full/10.1056/NEJMoa2205416

About Clinical Research Studies

Clinical research studies, also called clinical trials, look at an investigational medication or medical device to see if it is safe, how it works in the body, and if it works to treat a specific disease. Clinical research studies are conducted by doctors who are responsible for the study participants’ study-related care.

In most countries, the regulatory health authority, such as the Food and Drug Administration (FDA) in the United States or the European Medicines Agency (EMA) in Europe, requires that several phases of clinical research be performed to better understand the safety and effectiveness of new investigational medicines and certain medical devices.

Clinical research studies must be approved by an institutional review board (IRB) or ethics committee (EC). An IRB/EC is a group that is responsible for helping to protect the rights and well-being of study participants. In addition, every study participant is monitored with study-related medical tests and exams before, during and sometimes even after the study.

Participation in any clinical research study is completely voluntary, and participants may choose to leave the study at any time for any reason. If you would like to leave the study, you should discuss it with your study doctor, who will give you information about how to do this safely.

Before you can take part in The Redwood Study, you will first need to attend the screening visit(s) for initial tests and assessments to see if you are eligible to participate. After all necessary tests and assessments have been completed, and if you are eligible to participate, you may enter the treatment period of the study.

Participation in the study lasts approximately four and a half years.

Learn more about The Redwood Study.