Inotersen and Eplontersen: Antisense Therapies for hATTR Polyneuropathy
Antisense oligonucleotides (ASOs) are a second class of gene-silencing therapy for hATTR, working through RNA degradation at the cellular level rather than the RNAi pathway used by patisiran and vutrisiran. Two ASOs have been developed for hATTR: inotersen (Tegsedi, Ionis/Akcea) and the next-generation eplontersen (Wainua, AstraZeneca/Ionis). Inotersen was FDA-approved in 2018 for hATTR polyneuropathy based on the NEURO-TTR trial, which showed significant preservation of neurological function vs. placebo at 65 weeks. It's administered as a weekly subcutaneous injection. However, it carries a black box warning for thrombocytopenia (low platelets) and nephrotoxicity — patients require weekly platelet and renal monitoring, particularly in the first year. It is available through a REMS program. Eplontersen, approved by the FDA in December 2023, is an enhanced-generation ASO conjugated to GalNAc (liver-targeting ligand) allowing monthly subcutaneous dosing versus weekly for inotersen. The CARDIO-TTRansform trial showed a >80% TTR reduction and significantly improved neurological outcomes with a more favorable safety profile than inotersen — no mandatory REMS requirement. Eplontersen is now considered a leading option for patients preferring an injection over IV infusion and where vutrisiran is not the preferred choice.
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