Quitting Lilly's obesity drug tirzepatide may be difficult for many patients, exec says

On a day when Eli Lilly revealed stellar trial results for its obesity hopeful tirzepatide and spent more than half of its quarterly earnings presentation discussing the drug's prospects, there was a disquieting side note. 

Using tirzepatide might be a lifetime decision.

“Unfortunately, tirzepatide is probably like every other drug we have which requires you to take it to continue to get the benefits,” Dan Skovronsky, M.D., Ph.D., Lilly’s chief scientific and medical officer, said during a conference call.

With the success of Novo Nordisk’s diabetes and obesity duo, Ozempic and Wegovy—which have been fueled by impressive efficacy—Lilly has generated similar interest with its rival treatment.

Tirzepatide, which Lilly has commercialized as diabetes drug Mounjaro, won an FDA approval last May after it topped Ozempic in a head-to-head trial. In the first quarter, Mounjaro raked in $568 million in sales, with all but $32 million coming from the United States.

In trial results posted early on Thursday, overweight and obese diabetes patients lost an average of 15.7% of their body weight, for a median loss of 34 pounds, over 72 weeks when taking the medicine.

Analysts have pegged its peak sales in this indication at a staggering $25 billion. But because it is relatively new, little is known about the rebound effects when patients go off the drug.

“My expectation is that many patients may try coming off the drug completely to see what happens,” Skovronsky said. “Maybe some will be successful maintaining their weight, but many of them will probably experience some regression of their weight back toward baseline and this could prompt them to come back on the drug.”

Lilly has all the evidence it needs for an FDA submission to get an obesity approval, Lilly CEO David Ricks told CNBC. And the company is doing all it can to speed the process as it will use a priority review voucher to slice appraisal of the application from 10 to six months.

"We think the FDA will act quickly with a fast-track designation but we want to remove any uncertainty so we will be using a PRV and expect that we will get approval as early as the end of this year," Mike Mason, Lilly's diabetes chief, said. 

Mounjaro’s performance helped Lilly generate $6.96 billion in revenue during the first quarter, an 11% drop from the same period last year. The decline came thanks to a $1.5 billion drop in sales from COVID-19 antibodies.

Subtracting the COVID revenue from the equation produces a 10% revenue increase year over year. As a result, Lilly jacked up its 2023 revenue guidance to a range of $31.2 billion to $31.7 billion, up from its previous estimate of $30.3 billion to $30.8 billion.

Diabetes treatment Trulicity generated sales of $1.98 billion for the quarter, up 14% from $1.74 billion a year ago.

Also making impressive gains was breast cancer treatment Verzenio, which generated $751 million in sales, a 60% increase. Further, diabetes drug Jardiance delivered a 38% revenue increase to $577 million for the quarter.