New Oral Peptide Pills Could Replace Injectable Cholesterol-Lowering Antibodies

This was a medicinal chemistry optimization study. The team designed and synthesized a series of bi- and tricyclic peptide PCSK9 inhibitors, refining their chemical structures to improve potency and oral absorption. They used X-ray crystallography to understand how the peptides bind their target. The best candidates were tested in rats and cynomolgus monkeys for oral bioavailability, and the lead compound was evaluated in monkeys for its ability to engage PCSK9 and lower LDL cholesterol levels.

Millions of people worldwide take injectable PCSK9 antibodies like Repatha (evolocumab) and Praluent (alirocumab) to manage high cholesterol and reduce heart disease risk. However, the need for regular injections limits who is willing to use them. A once-daily oral pill that works just as well could dramatically increase the number of patients who benefit from PCSK9-targeted therapy, similar to how statins became widely used because of their convenience.

This work sits at the cutting edge of peptide drug delivery — the long-standing challenge of making peptides survive the gut and reach the bloodstream. If successful in humans, oral PCSK9 peptide inhibitors could join the growing wave of oral peptide drugs (like oral semaglutide) that are replacing injectable treatments. It also validates macrocyclic peptide chemistry as a platform for targeting protein-protein interactions that were previously considered 'undruggable' by small molecules.

All testing was done in animals (rats and monkeys), with no human data yet available. The oral formulation required special 'enabled' delivery technology, meaning a standard pill might not work. Long-term safety has not been established. Sample sizes for the animal studies were not specified in the abstract, and it remains to be seen whether the results will translate to humans.