Clinical Trials Arena

Ionis Pharmaceuticals to pursue approval of FCS drug after Phase III win

If given the green light, Ionis Pharmaceuticals’ olezarsen could be the first FDA-approved drug for familial chylomicronemia syndrome (FCS).

Ionis Pharmaceuticals is pursuing regulatory approval after primary candidate olezarsen met the primary endpoint in a pivotal trial in adults with familial chylomicronemia syndrome (FCS).

The Phase III Balance trial was a global, multicentre, randomised, double-blind, placebo-controlled study (NCT04568434) which enrolled 66 patients aged 18 years and older with confirmed FCS. In the study, patients were treated with olezarsen 80mg or 50mg, or placebo once every four weeks for 53 weeks.

Olezarsen 80mg met the primary endpoint of significantly reducing triglycerides (TGs) in patients with genetically validated FCS at six months. Patients in the 50mg group saw TG-reduced levels but these were not statistically significant.

The data also showed that olezarsen demonstrated robust and sustained reductions in TGs and serum apolipoprotein C-III (apoC-III) levels. It also reduced the incidence of acute pancreatitis (AP) events over the 12-month treatment period compared to placebo.

Eleven episodes of AP occurred in the placebo group versus one episode in the 80mg olezarsen group and one episode in the 50mg group.

A favourable safety and tolerability profile was observed, with a higher number of treatment-emergent adverse events (TEAEs) in the placebo group. There were no serious TEAEs related to olezarsen.

Based on these data, Ionis will be pursuing regulatory approval of olezarsen as a potential breakthrough treatment for adults with FCS.

Olezarsen is an RNA-targeted investigational ligand conjugated antisense (LICA) candidate. It acts by inhibiting the body's production of apoC-III, a protein that regulates triglyceride metabolism in the blood.

The US Food and Drug Administration (FDA) granted olezarsen fast track designation for the treatment of FCS in January 2023. The candidate then received orphan drug designation and breakthrough therapy designation in February 2024.

Ionis is also evaluating olezarsen for the treatment of severe hypertriglyceridemia (sHTG).

FCS landscape

FCS is a rare autosomal recessive disorder caused by a mutation in lipoprotein lipase. FCS is characterised by the body's inability to break down fats in the blood, leading to the accumulation of chylomicrons. This can cause severe health complications such as pancreatitis and cardiovascular disease.

Currently, there are no FDA-approved therapies to treat FCS.

One potential approach in the treatment of FCS is the development of drugs that can specifically target the metabolic pathways involved in the accumulation of chylomicrons.