Pfizer announced plans to discontinue the development of bococizumab, an investigational proprotein convertase subtilisin kexin type 9 inhibitor (PCSK9i). 

All of the available clinical data on bococizumab, taken with other lipid-lowering drugs, shows that it is not likely to be valuable to patients, physicians, or shareholders. Accordingly, Pfizer has decided to discontinue the global development program, which includes two ongoing cardiovascular outcome studies. 

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After the completion of six lipid-lowering studies under the Phase 3 SPIRE program, the Company noted several effects in the clinical profile of bococizumab: an attenuation of low-density lipoprotein cholesterol (LDL-C) lowering over time, a higher level of immunogenicity, and higher incidence of injection-site reactions vs. other agents in the PCSK9i class. Top-line data had shown all six studies had met their primary endpoints resulting in a significant reduction in the percent change from baseline in LDL-C at 12 weeks vs. placebo in adults with primary hyperlipidemia or mixed dyslipidemia at high and very high risk for cardiovascular events who were receiving statin therapy.

Bococizumab was being investigated for its potential to lower LDL-C and improve cardiovascular outcomes. PCSK9i drugs work by blocking the function of the PCSK9 protein, which interferes with the clearance of LDL-C. 

Pfizer will now stop the two ongoing cardiovascular outcome studies, SPIRE-1 and SPIRE-2. Scientific data will be made available for independent analysis and public presentation. 

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