A Study to Assess the Long-Term Safety and Efficacy of Eplontersen in Patients with Hereditary Transthyretin-Mediated Amyloid Polyneuropathy

Eligibility of study

1. Satisfactory completion of ION-682884-CS3 (NCT04136184) (Index Study) as judged by thevestigator and Sponsor, or diagnosis of hATTR-PN and satisfactory completion ofher study ISIS 420915-CS101 or study 2018-P001436 (NCT03702829) (both arevestigator-Sponsored studies with inotersen - the unconjugated version of) as judged by the Investigator and Sponsor.
2. Must have given written informed consent (signed and dated) and any authorizationsquired by local law and be able to comply with all study requirements.
3. Satisfy the following:
   1. Females: must be non-pregnant and non-lactating and either:
      • Surgically sterile (e.g., tubal occlusion, hysterectomy, bilateralgectomy, bilateral oophorectomy);
      • Post-menopausal (defined as 12 months of spontaneous amenorrhea in females >55 years of age or, in females ≤ 55 years, 12 months of spontaneoushea without an alternative medical cause and follicle-stimulatinghormone (FSH) levels in the postmenopausal range for the laboratoryvolved;
      • Abstinent*;
      • If engaged in sexual relations of child-bearing potential, agree to usehighly effective contraceptive methods from the time of signing the informeduntil at least 24 weeks after the last dose of Eplontersen andgree to receive pregnancy tests per protocol.
   2. Males: Surgically sterile (i.e., bilateral orchidectomy) or abstinent*, if
      engaged in sexual relations with a woman of child-bearing potential (WOCBP), thehe participant's non-pregnant female partner must use a highlyve contraceptive method from the time of signing the informed consent formuntil at least 24 weeks after the last dose of Eplontersen. *Abstinence (i.e.,g from heterosexual intercourse throughout the duration of study) is only acceptable as true abstinence, i.e., when this is in linewith the preferred and usual lifestyle of the participant. Periodic abstinence(e.g., calendar, ovulation, symptothermal, post-ovulation methods), declarationbstinence for the duration of a trial and withdrawal are not acceptablehods of contraception.
4. Willingness to adhere to vitamin A supplementation per protocol.

1. Have any new condition or worsening of existing condition that in the opinion of thevestigator or Sponsor would make the participant unsuitable for enrollment or couldwith the participant taking part in or completing the study.