Mixed Results for Bococizumab in PCSK9 Inhibition

Pfizer’s discontinued PCSK9 inhibitor bococizumab is no longer available, after the company pulled it from the market in November, 2016.

But in a research study presented at the American College of Cardiology’s 66^th Annual Scientific Sessions today, researchers said the drug did show significant benefit in preventing cardiac events in people with baseline LDL cholesterol higher than 100 mg/dL.

In trials known as SPIRE 1 and SPIRE 2, Paul Ridker, MD, a cardiologist at Brigham and Women’s Hospital in Boston said the drug proved safe but had mixed results on efficacy. The trials were ended early.

When Pfizer discontinued the trials, the reason given was an unanticipated attenuation of the drug’s ability to lower LDL over time. Even when it worked, however, there was wide variation in how patients responded. That could suggest genetic variations in the patients who received it, differences leading some individuals to develop antibodies to the drug.The fact that there were more injection site reactions in patients who did not see major cholesterol reductions with the drug bolstered that theory, the researchers said.

The study results “Support the general idea that further reduction in LDL, beyond what you can achieve with a statin further lowers cardiovascular event rates,” Ridker said, adding that “It is encouraging that we found a statistically significant reduction in events among the highest-risk patients who had the highest LDL levels.”

The drug trials enrolled 4,449 patients.

Subjects had a range of risk factors for heart disease. All had a known cardiovascular disease or had a combination of diabetes, chronic kidney disease or peripheral vascular disease with additional cardiovascular risk factors.

Most of the participants also took high-dose statins. The PCSK9 inhibitor was administered at a dose of 150 mg by subcutaneous injection.