Esperion shares have fallen over 8% today as The Medicines Co and Alnylam released early data on their RNAi candidate, ALN-PCSsc, targeting PCSK9. The drug was shown to efficiently and safely reduce LCL-C when given subcutaneously. It was shown to maintain LCL-C suppression 140 days after a single 1.5 ml injection. The long duration of response may allow for a quarterly and potentially bi-annual dosing schedule.

Such convenience not only presents a challenge to other PCSK9 inhibitors but also encroaches on one of Esperion’s major selling points for its oral drug ETC-1002. This news only serves to reinforce worries that the market for ETC-1002 is much smaller than anticipated- a principal concern driving down ESPR shares following its End Of Phase 2 (EOP2) FDA meeting update.

Since this August 17 update, Esperion has lost over one-third of its value.

Author is Long ESPR