Post-heparin plasma lipase activities in patients with severe hypertriglyceridemia treated with evinacumab

Patients with severe hypertriglyceridemia (sHTG) have variable lipoprotein lipase (LPL) activity levels that may influence therapeutic response. This exploratory analysis investigated post-heparin triglyceride lipase and phospholipase activities in three cohorts of patients with sHTG who received evinacumab (angiopoietin-like 3 inhibitor) for 12 or 24 weeks during a phase 2 trial: cohort 1, familial chylomicronemia syndrome with bi-allelic loss-of-function (LOF) LPL pathway mutations; cohort 2, multifactorial chylomicronemia syndrome (MCS) with heterozygous LOF LPL pathway mutations; and cohort 3, MCS without LPL pathway mutations. Post-heparin plasma samples were obtained at baseline and at week 24 (end of the treatment period). Triglyceride lipase activities (LPL and hepatic lipase [HL]) were measured using both a colorimetric and a scintillation assays. Phospholipase activities (HL and endothelial lipase [EL]) were measured using a colorimetric assay. Baseline post-heparin LPL triglyceride lipase activity was lowest in cohort 1; treatment with evinacumab for 12 or 24 weeks did not alter activity at week 24 versus baseline across cohorts using the colorimetric assay. Non-HL triglyceride lipase activity (mostly LPL) assessed using the scintillation assay showed a significant increase in cohort 1 at 24 weeks versus baseline (P = 0.04). Neither HL nor EL phospholipase activities differed among cohorts or changed with evinacumab treatment. High intra- and inter-patient variability in lipase activity was observed with all methods. Post-heparin LPL triglyceride lipase activity was lower in patients with sHTG with bi-allelic LPL pathway mutations and increased in that group with evinacumab. The high variability in lipase activities observed via differing methods supports the need for more robust assays.