Pfizer Inc. announced yesterday that it is discontinuing global clinical development of bococizumab, a monoclonal antibody inhibitor of PCSK9 that was being investigated as a lipid-lowering drug.  After completing the last of six planned clinical efficacy studies of bococizumab, Pfizer stated that it observed that the drug’s lipid-lowering activity declines over time and that it causes more significant adverse events compared with other drugs in its class.

The Wall Street Journal reports that drugs targeting PCSK9 were once believed to be a $20 billion market, but that Pfizer CEO Ian Read cited restrictions imposed by payers on the use of PCSK9 inhibitors as having “meaningfully dampened [Pfizer’s] initial expectations for the market potential.”  According to Mr. Read, these changes in the market also contributed to Pfizer’s decision to terminate bococizumab development.