Sanofi's and Regeneron Pharmaceuticals' Praluent (alirocumab) and Amgen's Repatha (evolocumab) not only are the guinea pigs for how the FDA will handle the first proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitor applications, but the drugs also are expected to be trailblazers in the marketplace for what's coming behind them – notably Pfizer's bococizumab, which is catching up fast to the two leaders.