Lomitapide-induced fatty liver is a reversible condition: evidence from a case of familial chylomicronemia syndrome

: Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive disorder characterized by severe hypertriglyceridemia. It is caused by loss-of-function variants in the genes encoding the lipoprotein lipase (LPL) enzyme and its cofactors, which severely impair the hydrolysis of triglycerides (TG). Its main complication is represented by acute pancreatitis (AP), a potentially life-threatening condition. Conventional TG-lowering therapies are poorly effective in FCS, thus requiring the search of novel treatments. Lomitapide, an inhibitor of microsomal triglyceride transfer protein (MTP), has demonstrated efficacy in reducing TG levels in FCS. However, it is associated with hepatic side effects, namely liver fat accumulation. Here we present a case study of a 71-year-old female patient with genetically confirmed FCS, baseline TG level of 2300 mg/dL (25.97 mmol/L) and a history of AP, who was treated with lomitapide for almost 5 years. The treatment allowed a marked reduction of TG (about 90%) and no recurrence of AP. However, hepatic monitoring during treatment revealed a progressive worsening of liver fat accumulation as detected by magnetic resonance imaging (MRI), which was associated with pronounced increases in liver transaminases and liver stiffness (up to 15 kPa). Due to these hepatic adverse events, it was decided to discontinue therapy with lomitapide. An MRI scan repeated after 70 days of drug withdrawal revealed complete resolution of fatty liver disease associated with normalization of liver stiffness (4.1 kPa) and liver transaminases. This case demonstrates the reversibility of lomitapide-induced fatty liver and underscores the importance of regular monitoring of the liver safety during lomitapide to guide timely interventions.