BACKGROUND:Severe hypertriglyceridemia (HTG), defined as a serum triglyceride (TG) concentration ≥500 mg/dl, is present in approximately 1 in every 100 individuals and carries direct clinical consequences, including pancreatitis, which can be life-threatening. Olezarsen is an investigational antisense oligonucleotide targeted to the mRNA for apolipoprotein C-III (apoC-III), a protein known to impair TG clearance by inhibiting lipoprotein lipase and the hepatic uptake of triglyceride-rich remnants. No dedicated trial has tested olezarsen in patients with severe HTG. METHODS:In these 2 pivotal phase 3 trials, CORE-TIMI 72a and CORE2-TIMI 72b, patients with severe HTG were randomized in a 2:1 fashion to either olezarsen (80 mg or 50 mg dose) or matching placebo. Patients will be treated for a total of 12 months and evaluated for the primary endpoint of percent change in TGs from baseline to 6 months compared with placebo. Pooled analyses of CORE and CORE2 will also assess olezarsen's effect on acute pancreatitis events and change in hepatic steatosis. RESULTS:A total of 617 subjects in CORE-TIMI 72a and 446 subjects in CORE2-TIMI 72b were randomized. In these 2 trials, the median age was 54 and 55 years, women made up 24% and 23% of the study population, and the baseline TGs were 836 mg/dl and 749 mg/dl, respectively. A total of 333 subjects, 129 from CORE-TIMI 72a and 204 from CORE2-TIMI 72b, were enrolled in the hepatic MRI substudy. DISCUSSION:Together, CORE-TIMI 72a and CORE2-TIMI 72b are designed to establish the efficacy and safety of olezarsen in patients with severe HTG. TRIAL REGISTRATION:Clinicaltrials.gov: NCT05079919 and NCT05552326.