Fixed-dose combination of obicetrapib and ezetimibe for LDL cholesterol reduction (TANDEM): a phase 3, randomised, double-blind, placebo-controlled trial

Background: Reducing LDL cholesterol prevents atherosclerotic cardiovascular disease (ASCVD) events. The aim of this study was to evaluate the LDL cholesterol-lowering efficacy of a fixed-dose combination (FDC) of obicetrapib, a CETP inhibitor, and ezetimibe. Methods: This randomised, double-blind trial across 48 US sites including hospitals, private and group practices, and independent research centres included participants at least 18 years old with pre-existing or high risk for ASVCD or heterozygous familial hypercholesterolaemia with LDL cholesterol concentrations of 1·8 mmol/L (70 mg/dL) or greater despite maximally tolerated lipid-lowering therapy excluding ezetimibe, or having statin intolerance. Participants were randomly assigned (1:1:1:1) to obicetrapib 10 mg plus ezetimibe 10 mg FDC, obicetrapib 10 mg monotherapy, ezetimibe 10 mg monotherapy, or placebo administered daily for 84 days. The co-primary endpoints in the intention-to-treat population were the percent LDL cholesterol changes in the FDC group compared with placebo, ezetimibe monotherapy, and obicetrapib monotherapy, and the placebo-adjusted change in the obicetrapib monotherapy group. The trial was prospectively registered (NCT06005597) and is completed. Findings: Between March 4 and July 3, 2024, 407 participants were randomly assigned. The median age was 68·0 years (IQR 62·0–73·0) and 177 (43%) were female. Mean baseline LDL cholesterol was 2·4 mmol/L, 2·5 mmol/L, 2·6 mmol/L, and 2·5 mmol/L in the placebo (n=102), ezetimibe monotherapy (n=101), obicetrapib monotherapy (n=102), and FDC groups (n=102), respectively. At day 84, percent differences in LDL cholesterol reduction with the FDC were –48·6% (95% CI –58·3 to –38·9) versus placebo, –27·9% (–37·5 to –18·4) versus ezetimibe, and –16·8% (–26·4 to –7·1) versus obicetrapib. Obicetrapib monotherapy decreased LDL cholesterol by 31·9% (22·1 to 41·6) versus placebo. Adverse event rates were similar in the FDC (52 [51%] of 102), obicetrapib (55 [54%] of 102), and ezetimibe (54 [53%] of 101) groups and lowest with placebo (38 [37%] of 102). Serious adverse event rates were generally similar across FDC (three [3%] of 102), obicetrapib (six [6%] of 102), ezetimibe (seven [7%] of 101), and placebo (four [4%] of 102) groups. Deaths occurred in one [1%] of 102 participants with FDC, one [1%] of 102 with obicetrapib, one [1%] of 101 with ezetimibe, and none with placebo. Interpretation: Combination therapy of obicetrapib and ezetimibe significantly reduced LDL cholesterol. This oral, single-pill therapy could improve LDL cholesterol management in patients with pre-existing or high risk for ASCVD. Funding: NewAmsterdam Pharma.