Open-Label Extension and Safety Monitoring Study of Acoramidis (AG10) in Participants with Symptomatic Transthyretin Amyloid Cardiomyopathy Who Completed the Phase 3 ATTRibute-CM Trial (AG10-301)

The primary objective of this prospective, multi-center, open-label study is to evaluate the long-term safety and tolerability of acoramidis in patients with an established diagnosis of ATTR-CM and heart failure who are concomitantly treated with currently recommended heart failure therapies. Secondary efficacy and PD objectives will be assessed. Exploratory objectives may also be assessed.

All participants who complete 30 months of blinded study treatment and the Month 30 assessments of the double-blind treatment period of the Phase 3 ATTRibute-CM trial (AG10-301) may be eligible to participate in this Open Label Extension (OLE) study of acoramidis. The Day 1 visit in Study AG10-304 may be the same as the Month 30 visit in Study AG10-301. Under these circumstances, the last dose of Investigational Medicinal Product (IMP) in Study AG10-301 (either blinded acoramidis or matching placebo) will be the night before the day of the Month 30 visit. The first dose of open-label acoramidis in Study AG10-304 will be during the Study AG10-304 Day 1 visit after baseline assessments have been completed.

Currently, tafamidis is approved for the treatment of ATTR-CM in some regions. Participants are not allowed to be treated with tafamidis or any other ATTR-CM-specific approved or investigational treatment, or therapies used off-label or as non-prescription supplements for ATTR-CM at any time during the study. If participants choose treatment with an alternative treatment as described above, they will be asked to discontinue acoramidis and complete an End of Treatment (EoT) form, and they may be asked to discontinue/withdraw from the study. If a participant discontinues/withdraws from the study, the participant will be asked to complete an early termination visit and a safety follow-up visit.

Participants are not permitted to participate in another interventional clinical trial (except Study AG10-301) within 30 days prior to dosing and throughout Study AG10-304. Participants who choose to participate in another interventional clinical trial will be asked to withdraw from acoramidis and complete an EoT form, and they may be asked to discontinue/withdraw from the study. If a participant discontinues/withdraws from the study, the participant will be asked to complete an early termination visit and a safety follow-up visit. Participation in observational and/or registry studies should be discussed with the Medical Monitor.

Inclusion Criteria:

1. Completed 30 months of the blinded study treatment in Study AG10-301 and the Study AG10-301 Month 30 visit including assessments and procedures.
2. Have the ability to understand and sign a written informed consent form, which must be obtained prior to initiation of study procedures.
3. Female participants of childbearing potential who engage in heterosexual intercourse must agree to use a highly effective method of contraception beginning with enrollment and continuing for 30 days after the last dose of acoramidis. Female participants using oral contraceptives must agree to use an additional birth control method. While not considered highly effective, a double-barrier method is acceptable. A male participant who is sexually active with a female of childbearing potential and has not had a vasectomy must agree to use a double-barrier method of birth control.

Exclusion Criteria:

1. Acute myocardial infarction, acute coronary syndrome or coronary revascularization within 90 days prior to Day 1 stroke or transient ischemic attack (TIA) within 90 days prior to Day 1.
2. Has hemodynamic instability, that in the judgment of the Investigator, would pose too great a risk for participation in the study.
3. Has had a heart and/or liver transplant or is on the heart transplantation list within the year prior to Day 1
4. Has had implantation of a cardiac mechanical assist device (CMAD) or is scheduled for implantation of a CMAD
5. Has confirmed diagnosis of light-chain (AL) amyloidosis at any time during Study AG10-301.
6. Has estimated glomerular filtration rate (eGFR) by modification of diet for renal disease (MDRD) formula < 15 mL/min/1.73 m2 at Month 27 of Study AG10-301 or at any subsequent central lab value prior to Day 1.
7. Known hypersensitivity to acoramidis, its metabolites, or formulation excipients.
8. At the end of Study AG10-301 or at Day 1 of Study AG10-304 (or any time during the study), participant is on prohibited medication.
9. Females who are pregnant or breastfeeding. A negative urine pregnancy test at the Day 1 visit and at each study visit are required for female participants of childbearing potential.
10. In the judgment of the Investigator or Medical Monitor, has any clinically important ongoing medical condition or laboratory abnormality or condition that might jeopardize the participant's safety, increase their risk from participation, or interfere with the study.
11. Participation in another interventional clinical trial (with the exception of Study AG10-301) within 30 days prior to dosing. Participation in observational and/or registry studies should be discussed with the Medical Monitor.
12. Has any condition that in the opinion of the Investigator or Medical Monitor would preclude compliance with the study protocol such as a history of substance abuse, alcoholism, or a psychiatric condition.