An evaluation of patisiran: a viable treatment option for transthyretin-related hereditary amyloidosis

Introduction: Hereditary transthyretin-mediated amyloidosis (ATTRv; v for variant) is a rare, progressive, fatal multi-systemic disease, autosomal dominantly inherited with heterogeneous clinical phenotype caused by mutations in the TTR gene. Mutations promoting proteolytic remodeling and tetramer dissociation result in fragmented and full-length TTR monomers that misfold, aggregate and deposit at multiple sites (mainly nerves and heart) causing peripheral neuropathy and/or cardiomyopathy. Areas covered: The authors discuss patisiran, the first approved RNA interference-based therapeutic agent that suppresses the circulating levels of the amyloidogenic protein TTR both wild-type and mutant. This compound demonstrated a safe clinical profile in phase I and II studies and showed a significant clinical effect in a phase III (APOLLO) trial in ATTRv patients. An open-label-extension study is still underway but, based on the positive results, the regulatory agencies granted approval for the treatment of ATTRv with polyneuropathy in Stage I and II. Expert opinion: The patisiran program has demonstrated that substantial TTR concentration reduction is associated with significant and sustained improvement in polyneuropathy scores, quality-of-life profile and several outcome measures that capture the systemic burden of the disease. The drug resulted safe also in long term follow-up studies while its efficacy for ATTR with cardiomyopathy is under investigation.