About the DepleTTR-CM Study

The DepleTTR-CM Study is evaluating the safety and effectiveness of an amyloid depleter investigational medication in adults with transthyretin amyloid cardiomyopathy (ATTR-CM). This is a depleter study, which aims to target the active removal of pre-existing amyloids and restore heart function and elasticity.

Who May Qualify

Eligible participants must:

  • Be 18 to 90 years of age
  • Have a confirmed diagnosis of ATTR-CM with transthyretin (TTR) that is either:
    • wild-type TTR
    • a variant TTR genotype
  • Be willing to be genetically tested for mutations in the TTR gene
  • NOT have received prior treatment with an ATTR amyloid depleter

There are additional eligibility requirements that the study doctor can explain to you.

Study Participation

Participation in the DepleTTR-CM Study lasts about two and a half to four and a half years and consists of three periods:


This 35-day period will determine study eligibility.


This period lasts two to four years and has 56 study site visits. Participants will be randomized to receive either the investigational medication or a placebo. The assigned study treatment will be administered once every four weeks as a one- to two-hour infusion. All infusion visits will include a two-hour post-treatment observation period. Assessments, like a six-minute walk test to evaluate how well a participant’s body is functioning, and questionnaires about how ATTR-CM affects everyday life, will be performed at the study site.

Safety Follow-Up

After completing the treatment period, participants will enter a four-month safety follow-up period with two visits, one visit every two months, to have their health monitored by the study team.

Participants who complete the treatment period may be eligible to enter an open-label extension study, where all participants will receive the investigational medication, even if they received the placebo in the DepleTTR-CM Study.

Throughout the study, the study doctor may perform a number of tests and procedures, including but not limited to:

  • Recording medical history

  • Conducting physical exams

  • Measuring vital signs

  • Conducting pregnancy tests (if applicable)

  • Collecting blood and urine samples

  • Imaging assessments

About the Investigational Medication

In this clinical research study, the investigational medication (ALXN2220) is being compared to a placebo. A placebo is a drug that contains no active ingredients and allows researchers to understand the effects of an investigational medication more fully. During this study, neither participants nor their study doctor will know which study treatment participants have been assigned, but in case of an emergency, the study doctor can quickly find out.

The investigational medication or the placebo will be administered once every four weeks via a one- to two-hour intravenous (IV) infusion, meaning that fluids will be administered directly into a vein. The investigational medication is a transthyretin (TTR) depleter that aims to remove pre-existing amyloids, reduce stiffness of the heart muscles, and improve heart elasticity – all of which may result in improved quality of life for individuals with ATTR-CM.

During the DepleTTR-CM Study, participants may be able to remain on their existing standard-of-care therapies.

Measuring Investigational Medication Effectiveness

To measure the effectiveness of the investigational medication, the study team will review any health changes during visits by performing a wide variety of assessments, including:

Kansas City Cardiomyopathy Questionnaire Overall Score (KCCQ-OS)

By answering a 23-item questionnaire about heart failure symptoms and impact on quality of life, the study team can measure a participant’s health status as compared to the beginning of the study. This questionnaire has been used in other ATTR-CM studies.

Blood sampling

Through blood samples, the study team will measure changes in a participant’s natriuretic peptides (substances made by the heart) as compared to the beginning of the study. This will determine if amyloid deposits are being removed by the investigational medication.

Six-minute walk test

Participants will walk at a normal pace for six minutes to measure how their body systems are working while exercising. Participants that require a walking aid or oxygen will be allowed to use them during this assessment.