ION-682884 in Patients With TTR Amyloid Cardiomyopathy

Transthyretin is a protein produced in the liver that transports thyroid hormone and vitamin A. A single substitution of an amino acid in the structure of TTR can result in a relatively unstable protein, the breakdown products of which (predominantly monomers) aggregate abnormally and produce proteinaceous deposits in nerves and the heart. These deposits are known as amyloid and produce progressive nerve and heart damage. Amyloidosis due to a mutant TTR is usually an autosomal dominant and hence is a familial condition. Wild-type TTR is also capable of producing amyloid deposits which predominantly involves the heart (rather than the nervous system) resulting in a progressive decrease in cardiac function with increasing signs of heart failure. This study aims to determine whether subcutaneous injection of an antisense oligonucleotide drug, known as ION-682884, that has been specifically designed to reduce production of the protein transthyretin by the liver, can slow or stop the progression of TTR amyloid cardiomyopathy as compared to historical controls, using advanced echocardiography and cardiac MRI. This study drug will only be administered to patients who have completed a 24-month study of a similar drug, inotersen (clinicaltrials.gov identifier NCT037028289).The study also aims to determine the tolerability and safety of this drug when administered over a 36+-month period to patients with TTR amyloid cardiomyopathy. The study duration is open-ended and will continue either until this agent is approved by the FDA, or production is discontinued based on results of ongoing double-blinded studies.