Successful Rituximab Treatment of GPIHBP1 Autoantibody-Associated Hypertriglyceridemia

BACKGROUND: A 50-year-old woman had triglyceride values up to 1640 mg/dL on routine laboratory tests. Despite the initiation of fenofibrate, icosapent ethyl, rosuvastatin, and a low-fat diet, her triglyceride values ranged from 1200 to more than 8200 mg/dL, and she had recurrent pancreatitis. CASE SUMMARY: Testing was negative for mutations in chylomicronemia genes such as LPL, APOC2, APOA5, LMF1, and GPIHBP1. Additional testing revealed elevated autoantibodies to GPIHBP1 up to 2,336 U/mL (normal <58 U/mL) and decreased GPIHBP1 to 2.5 pg/mL (normal range 570-1,625 pg/mL), confirming GPIHBP1 autoantibody syndrome (GPIHBP1-AAS). The patient received rituximab 1000 mg infusion, with 2 doses given 3 weeks apart. Triglycerides decreased from 1,746 to 81 mg/dL within 4 months and remained normal 12 months later without repeat dosing. DISCUSSION: GPIHBP1-AAS was only recently described and is associated with severe hypertriglyceridemia and recurrent pancreatitis. In our case, treatment with rituximab was very effective. TAKE-HOME MESSAGE: GPIHBP1-AAS-associated hypertriglyceridemia should be recognized and can be successfully treated with rituximab.