In the wake of the imbroglio over pricing of hep.-C drugs and subsequent payer pushback, the pharma world steeled itself for a second wave of battles over PCSK9 drug prices. It was expected that the new class of cholesterol-lowering products, the first two of which were approved by the FDA in July (Sanofi/Regeneron’s Praluent) and August (Amgen’s Repatha), would reopen old wounds that hadn’t yet healed.

And yet here we are, several months later, and many payers haven’t yet anointed one PCSK9 over the next. Nor have they publicly taken the makers to task over pricing, positioning or anything else. If one were to characterize payer response so far in a word, it would be “measured.”

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There are plenty of reasons for this, of course. The primary one may be method of administration: Unlike the great majority of cholesterol drugs, Praluent and Repatha are injectibles. No data yet exist on whether injected cholesterol drugs improve patient compliance—and thus there’s no true urgency for payers to green-light a shift away from existing treatment regimens.

“Compliance is such a problem with cholesterol patients,” says Melinda Haren, senior director of access strategies at Zitter Health Insights. “When I was a nurse, patients would come in and say, ‘Of course I took the pill every day—except on Sunday, because I was going out to dinner with my family after church, and sometimes on Tuesday, because it was Bingo Night.’ That’s a long way of saying that with PSCK9s, what could change the equation is if we see better adherence [with Praluent and Repatha]. I mean, nobody’s saying the drugs don’t do what they claim to do.”

Ultimately, it’s possible that payers won’t prove the wild card in the PCSK9 derby. Instead, physician preference—and the handful of unpredictabilities that comes with it—may do more to shape the market and maybe even force payers’ hands. At the same time, it’s worth noting that cardiologists don’t have much experience with injectible cholesterol drugs like Praluent and Repatha, so it’s anybody’s guess how this will play out vis-à-vis their interaction with patients.

“Everybody talks about the payers, but there’s a momentum that starts with physicians. Doctors, just like all of us, are creatures of habit. If they’ve had success with a drug they prescribed, they’ll stick with it,” Haren says.

Too, Haren believes that payers’ experience with transformative hep.-C products from AbbVie and Gilead Sciences has informed their less aggressive approach to PCSK9s. “What happened with HPV reminded payers that it’s easier to get rebates on a drug being prescribed than to attempt to dictate a plan,” she explains. “Take Express Scripts—for hep. C they chose the wrong horse [AbbVie’s Viekira Pak]. Doctors were saying, ‘It’s a great new therapy, but there are multiple pills a day and the number of pills you take at different times is different. I’d rather prescribe Harvoni.’ With the PCSK9s, payers are saying, ‘Let the market decide’ and then they’ll go and try to get rebates on the quote-unquote winner.”

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This dynamic could be complicated, or upended altogether, if Pfizer’s new anticholesterol drug passes FDA muster and makes it to market later this year. “Three is the magic number for payers to get more aggressive. When there are three products, somebody like CVS or Express Scripts can officially prefer two and exclude the other,” Haren notes. “That’s why those early-review vouchers are so valuable—it’s why Sanofi bought one [for $67 million, to secure priority review of Praluent]. They would’ve been significantly behind if they hadn’t.”

The last product to market tends to be the one left without a chair when the music stops, but that assumes no significant differentiating factors. If the third-to-market next-gen cholesterol drug boasts a distinct clinical advantage or easier method of administration, or if Pfizer offers significant price discounts and/or patient support programs, all bets are off.