The study focuses on adults with Transthyretin-Mediated Amyloid Cardiomyopathy (ATTR-CM), a rare condition where abnormal protein builds up in the heart muscle, making it stiff and less able to pump blood. The treatment being tested combines two medicines: a subcutaneous (under‑the‑skin) injection of eplontersen, which helps reduce the problematic protein, and an intravenous (through a vein) infusion of ALXN2220, a specially designed antibody that also targets the protein. Participants will receive either this combination or the same eplontersen injection together with a placebo, which looks like the real medicine but does not contain the active drug.
The purpose of the study is to determine whether adding ALXN2220 to eplontersen improves the ability to exercise compared with eplontersen plus placebo. To assess this, participants will perform a cardiopulmonary exercise test (CPET), a breathing and exercise test that measures the maximum amount of oxygen the body can use during intense activity. The test will be done at the start of the study and again after about a year of treatment.
During the trial, participants will visit the clinic regularly for the subcutaneous injections, the intravenous infusions, and safety checks such as blood tests and heart examinations. The study will continue for roughly 52 weeks, with scheduled appointments to monitor how the heart is working and to record any side effects. All procedures are designed to follow standard safety guidelines.
France 
Sweden 
