A Phase III Study to Assess the Effect of AZD0780 on LDL-C in Patients With HeFH

Inclusion criteria: •≥ 18 years of age at the time of signing the ICF. * Diagnosis of HeFH by genetic confirmation or a definite clinical diagnosis, ie, a score \> x using the Dutch Lipid Network \[Nordestgaard et al 2013\] or equivalent as per internationally accepted diagnostic algorithms (AHA \[Gidding et al 2015\], US MEDPED \[Williams et al 1993\], Simon Broome \[Scientific Steering Committee on behalf of the Simon Broome Register Group 1991\], or Japanese Atherosclerosis Society Guidelines \[Okamura et al 2024\]) * Fasting serum by central laboratory at screening as follows: LDL-C ≥ 55 mg/dL (≥ 1.4 mmol/L) in participants with HeFH and clinical ASCVD or ≥ 70 mg/dL (≥ 1.8 mmol/L) in HeFH without clinical ASCVD. Clinical ASCVD is defined as MI, stable or unstable angina, coronary or other arterial revascularisation, ischaemic stroke, or peripheral artery disease. * Participants should receive a background lipid lowering regimen anticipated to achieve at least a \~50% reduction in LDL-C. Except in cases of intolerance, the regimen should include a high intensity statin therapy or lower intensity statin therapy in combination with an oral agent with proven outcome benefit (eg, ezetimibe and/or bempedoic acid). Thus, the background lipid-lowering therapy must consist of one of the following: \- A high intensity LDL lowering regimen (i) A high intensity statin regimen, as defined by country specific guidelines - Oral combination therapy with ezetimibe and/or bempedoic acid is strongly recommended OR: (ii) A lower intensity statin regimen in combination with ezetimibe and/or bempedoic acid : OR: \- A maximally tolerated statin regimen - Oral combination therapy with ezetimibe and/or bempedoic acid is strongly recommended. Participants must achieve a stable background lipid lowering therapy \> 28 days before screening. Exclusion criteria: * Homozygous familial hypercholesterolaemia, LDL apheresis or plasma apheresis within 12 months prior to screening, or any other underlying known disease or condition that may interfere with interpretation of the clinical study results as judged by the Investigator. * Any of the following laboratory values at screening: * Calculated eGFR \< 15 mL/min/1.73 m2 * AST or ALT \> 3 × ULN * TBL \> 2 × ULN (except for patients with Gilberts syndrome, where TBL 3 × ULN is acceptable provided direct bilirubin \< 1.5 × ULN) * Fasting triglycerides ≥ 400 mg/dL (≥ 4.52 mmol/L) * Creatine kinase \> 5 × ULN * Urine albumin-to-creatinine ratio ≥ 500 mg/g * Uncontrolled type 2 diabetes mellitus defined as HbA1c ≥ 9.5% at screening * Inadequately treated hypothyroidism defined as TSH \> 1.5 ULN at screening or participants whose thyroid replacement therapy was initiated or modified within the last 3 months prior to screening * Use of mipomersen or lomitapide (cholesterol-lowering medications) within 12 months prior to screening or planned use during the study. * Use of gemfibrozil within 1 week prior to screening or planned use during the study. * Use of PCSK-9 inhibitors: evolocumab/alirocumab within 12 weeks of the screening visit or planned use during the study or inclisiran within 18 months of the screening visit or planned use during the study. Any other approved PCSK-9 inhibitor use within 5 half lives prior to the screening visit or planned use during the study.