AZ's Onglyza has most to lose at FDA safety confab, analysts say

FDA experts will grill a couple of diabetes meds next Tuesday, and the outcome of that debate could put a damper on sales. The drugs: AstraZeneca's ($AZN) Onglyza and Takeda's Nesina, both DPP-4 blood sugar-fighters. The questions: Do they really increase the risk of heart failure? And if so, what's to be done about it?

There's a broader question, too. If these meds ratchet up the risk of heart failure, what does that say about the DPP-4 meds as a group, which includes Merck & Co.'s ($MRK) blockbuster Januvia franchise.

The FDA is convening an advisory committee to consider data from the SAVOR outcomes trial, which suggested that Onglyza patients were more likely to be hospitalized with heart failure. In the 16,000-patient study, 27% more Onglyza patients ended up in the hospital with heart failure, compared with patients in the control arm.

Meanwhile, in a Nesina outcomes trial dubbed EXAMINE, heart-failure hospitalizations were apparently higher in some groups of patients on the Takeda drug, but the increase for all patients wasn't statistically significant.

Leerink analyst Seamus Fernandez figures that Onglyza has the most to lose from this advisory panel meeting. If the experts affirm the heart-failure risks and suggest AstraZeneca change the drug's label accordingly, then doctors might well switch Onglyza patients to other meds. And Onglyza brought AstraZeneca $820 million last year.

AstraZeneca CEO Pascal Soriot

Plus, Onglyza is a key cog in AstraZeneca's diabetes machine. The U.K.-based company won full control of the drug in its 2013 buyout of Bristol-Myers Squibb's ($BMY) share in their longstanding diabetes partnership. Over the past couple of years, in deals with Bristol-Myers, the U.K.-based drugmaker has staked more than $7.5 billion on growing its diabetes franchise, and CEO Pascal Soriot calls diabetes one of AstraZeneca's top growth platforms.

But as important as it might be for AstraZeneca, Onglyza and its combo cousin Kombiglyze aren't the dominant players in the DPP-4 class. Those would be Januvia and Janumet, which make up a big chunk of Merck's revenue. And Januvia's cardiovascular outcomes data aren't yet available. The TECOS trial is set for presentation at the American Diabetes Association meeting in June.

Bernstein analyst Tim Anderson figures that the FDA has some idea of what the TECOS data shows. Otherwise, why schedule the AdComm for next week, rather than after the Merck trial reads out?

As Fernandez notes, Onglyza works in a slightly different manner from Januvia, so even if the panel affirms that SAVOR safety signal, that doesn't mean all DPP meds have the same problem. And Anderson points out that if TECOS clears the Merck drug, then Onglyza and Nesina might get label changes, without any changes for the rest of the class. 

If TECOS shows CV problems for Januvia, though, all bets are off. The DPP-4 class could see sales shrink by up to 15%, Anderson wrote in a recent note.

We'll have some answers when the FDA releases briefing documents for Tuesday's meeting, and even more than that next week. Until then, it's all about the questions.

Special Reports: The top 10 best-selling diabetes drugs of 2013