Pfizer has put on a late spurt in the race to bring a PCSK9 blocker class to market, reporting positive phase 2b data for bococizumab, which has now entered late-stage testing.

Results from the 24-week study show that bococizumab (RN316) was significantly better than placebo in reducing elevated LDL-cholesterol, a major risk factor for cardiovascular (CV) disease, in patients also taking statin drugs.

Bococizumab was effective when given as a once- or twice-monthly injection, said Pfizer, which started two phase 3 trials looking at the drug’s benefits on CV outcomes last October along with a number of smaller lipid-lowering studies that collectively will enrol around 22,000 people.

One of the trials – called SPIRE1 – will look at the effects of lowering LDL-cholesterol levels below current recommended targets, while the second (SPIRE-2) will enrol high-risk patients whose LDL-cholesterol levels are high (above 100mg/dL) despite statin therapy.

Pfizer says its clinical programme is the only one in the PCSK9 inhibitor category that is investigating CV outcomes in both high-risk primary and secondary prevention populations.

That goes beyond what has been considered to be the minimum for approval of a PPCSK9 inhibitor – robust LDL-cholesterol lowering along with a comprehensive long-term safety database – and could help differentiate the drug in the marketplace versus its rivals.

Dr Steven Romano, global medicines development lead at Pfizer’s Global Innovative Pharmaceutical business, said: “Recent guidelines emphasise the reduction of CV risk as the primary goal of lipid therapy for patients at risk for CV events.”

At the moment, Pfizer’s main rivals are Amgen with evolocumab and Sanofi and Regeneron with alirocumab, both of which are a little further along in development as they have already reported several positive phase 3 trials.

Analysts have predicted that the leaders in the PCSK9 inhibitor class could achieve multibillion dollar sales at peak, despite competition from low-cost generic statins.

One possible obstacle for the new class could be regulatory scrutiny of their potential to cause neurocognitive adverse events, which is under investigation by the FDA at the moment, although this is a perennial concern among drugs which have a potent effect on cholesterol metabolism, including statins.