A Study to Investigate the Effect of AZD0780 Tablets in Combination With Rosuvastatin Tablets on Low Density Lipoprotein Cholesterol Levels (LDL-C) in Adult Participants With Dyslipidaemia

Inclusion Criteria: * ≥ 18 years of age at the time of signing the ICF * History of clinical Atherosclerotic cardiovascular disease (ASCVD) or at risk for a first ASCVD event: 1. Clinical ASCVD is defined as MI, stable or unstable angina, coronary or other arterial revascularisation, ischaemic stroke, or peripheral artery disease. 2. A participant is considered at risk for a first ASCVD event if the participant has one or more of the following conditions: atherosclerotic vascular disease (≥ 50% stenosis in ≥ 2 coronary artery territories or in ≥ 2 vascular beds \[coronary, carotid, lower extremity\], diagnosed by any imaging modality), diabetes mellitus, hypertension, cigarette smoking, chronic kidney disease (moderate to severe stage), or obesity. Investigators can also use the ACC/AHA or ESC or national clinical guidelines for risk assessment to identify participants with at least moderate risk for ASCVD. * Fasting serum LDL-C by central laboratory at screening as follows: LDL-C ≥ 55 mg/dL (≥ 1.4 mmol/L) in participants with clinical ASCVD or ≥ 70 mg/dL (≥ 1.8 mmol/L) in participants without clinical ASCVD but at risk for a first ASCVD event * Participants should meet 1 of the following before screening: 1. On a stable dose of Lipid-lowering therapy (LLTs) including moderate statins. 2. On a stable dose of LLTs without any statins (either have been previously treated or be statins treatment naïve). 3. Not received treatment with any LLTs (either have been previously treated or be LLTs treatment naïve). Exclusion Criteria: * Homozygous familial hypercholesterolaemia, known diagnosis of heterozygous familial hypercholesterolaemia (HeFH), 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: 1. Calculated eGFR \< 15 mL/min/1.73 m2 2. AST or ALT \> 3 × ULN 3. TBL \> 2 × ULN (except for patients with Gilberts syndrome, where TBL 3 × ULN is acceptable provided direct bilirubin \< 1.5 × ULN) 4. Fasting triglycerides ≥ 400 mg/dL (≥ 4.52 mmol/L) 5. Creatine kinase \> 5 × ULN 6. 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.