Investigational PCSK9 inhibitor significantly reduces LDL cholesterol in phase 3 trials

Adults at high risk for cardiovascular events who received an investigational medication had significant reductions in low-density lipoprotein (LDL) cholesterol after 12 weeks of treatment, according to two phase 3 studies.

Pfizer, Inc. announced the top-line results on June 28. Patients enrolled in the study were randomized to receive placebo or bococizumab, a Pfizer drug that has not yet been FDA-approved.

Pfizer said it planned on presenting the full results at upcoming medical conferences, although the company did not provide information on the specific meetings. Pfizer also did not say when it would file a new drug application with the FDA for the drug’s approval.

The two trials were the third and fourth studies in Pfizer’s SPIRE program, which enrolled approximately 32,000 patients. The company expects the two remaining lipid-lowering trials to be complete by the end of 2016. So far, all four studies have met their primary endpoints. The program also includes two cardiovascular outcome studies, which will track the outcomes associated with bococizumab.

Bococizumab is part of a medication class known as proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors. Last summer, the FDA approved the first two PCSK9 inhibitors: alirocumab (Praluent, Regeneron Pharmaceuticals and Sanofi Aventis) and evolocumab (Repatha and Amgen).

The SPIRE-HR study enrolled 711 adults with primary hyperlipidemia or mixed dyslipidemia who had an LDL cholesterol level of at least 70 mg/dL while taking statins. They also had a known history of cardiovascular disease.

The SPIRE-FH study enrolled 370 adults with heterozygous familial hypercholesterolemia (HeFH) who were taking statins. They were eligible for the trial if they had a known history of cardiovascular disease, diabetes or chronic kidney disease and an LDL cholesterol level of at least 70 mg/dL or if they had an LDL cholesterol level of at least 100 mg/dL without a history of those conditions.

Pfizer said both studies met their primary endpoint, which was a significant reduction in LDL cholesterol from baseline. The company added that bococizumab was safe and tolerable in most patients.

“Overall, the proportion of patients experiencing adverse events was similar among treatment groups, with one exception of a higher incidence of injection site reactions seen for patients on bococizumab compared to those on placebo in both trials,” Pfizer said in a news release. “The majority of reported injection site reactions were mild.”