The success of the Reveal trial might go down as the clinical surprise of 2017. Merck & Co's (NYSE:MRK) anacetrapib, the last CETP inhibitor left standing, has significantly reduced major coronary events in a huge outcomes study, confounding widely held pessimism.

The news initially sent the company's stock higher this morning, but a notably cautious statement quickly restrained excitement. The fact that Merck has not committed to file for approval hints at a result that might not be clinically relevant, whatever the statistics are saying.

Full data are being held back for the ESC meeting at the end of August, so firm conclusions are impossible to draw at this stage - the company only said that the primary endpoint was met. However, headlining a press release with "provides update" is rarely a signal of good news.

And Merck has little reason to overstate its opportunity here; after the failure of three previous agents in this class hopes were low, while the huge success of Keytruda has relegated much else in its portfolio to a footnote.

Salvaging a signal

Developing the only successful CETP inhibitor would still be a coup, though. Lilly, Roche and Pfizer all invested heavily in their own agents, and their collective failure was costly, as well as dealing a heavy blow to the HDL hypothesis.

Little faith remains in the clinical benefits of this mechanism, and if anacetrapib starts to look more like a statin - in that it works by lowering LDL - Merck will have to consider that its rivals on the market are largely generic.

Anacetrapib, like Lilly's evacetrapib, aggressively lowers LDL while hiking HDL. However Merck opted to run a much longer and larger outcomes study than Lilly, a bold strategic decision that ultimately might have paid off.