Eli Lilly mounts clinical and commercial case for tirzepatide as Mounjaro, Zepbound chalk up major gains

Locked in a heated battle with Novo Nordisk’s semaglutide franchise, Eli Lilly’s tirzepatide is beginning to come into its own—both with regards to sales and amid attempts to show the dual GIP/GLP-1 agonist can strike out beyond diabetes and obesity.

As Mounjaro, tirzepatide won its first FDA nod in Type 2 diabetes back in May 2022. An obesity approval followed last November, with that formulation of tirzepatide adopting the commercial moniker Zepbound.

In 2023’s fourth quarter, Mounjaro generated a whopping $2.2 billion in sales, a nearly eight-fold increase over the $279 million it pulled down during the same stretch in 2022. Year-to-date, the drug brought home around $5.2 billion in revenues, Lilly said in an earnings release Tuesday. Zepbound, for its part, generated $175.8 million during its first quarter on the market.

Overall, Lilly reeled in around $9.4 billion in fourth-quarter sales, growing 28% over the $7.3 billion it made for the quarter in 2022. For the entire year, Lilly achieved sales of roughly $34.12 billion.

Mounjaro and Zepbound are currently duking it out with Novo Nordisk’s respective GLP-1 counterparts, Ozempic and Wegovy, which both hit the market ahead of Lilly’s meds. Even still, many analysts have predicted Lilly’s tirzepatide will ultimately eclipse semaglutide on the highly lucrative obesity scene.

In a bid to differentiate their meds and make a case for obesity as a chronic disease, both companies have made efforts to show their GLP-1s can go far beyond simply helping patients lose weight. Novo did this with its SELECT cardiovascular outcomes data in August, and now Lilly’s efforts on tirzepatide are starting to bear fruit, too.

Tucked into its year-end earnings report, Lilly revealed positive results from Synergy-NASH—its phase 2 study of tirzepatide in adults in nonalcoholic steatohepatitis (NASH), also known as metabolic dysfunction-associated steatohepatitis (MASH). In the trial, tirzepatide met its primary endpoint, helping up to 74% of patients achieve an absence of MASH with no worsening of fibrosis at the 52-week mark, compared to just 13% of patients on placebo.

While 2023 was certainly a good year for tirzepatide, the med’s popularity has led to a protracted supply squeeze. Earlier this week, the FDA added two more doses of the drug to its shortage database, which now lists 10-mg, 12.5-mg and 15-mg doses of Mounjaro as being in limited supply through early March.

Lilly is still shipping all Mounjaro doses to wholesalers, a Lilly spokesperson confirmed via email. That said, the current market is “dynamic,” posing “ongoing fluctuation in demand,” she said. This means intermittent regional pharmacy stock outages are “still possible.”

Lilly, like Novo Nordisk, has been working intently to stand up additional manufacturing and supply capacity around the world to endure the heightened GLP-1 demand.

“The addition of our manufacturing facility in North Carolina, coupled with additional actions and expansions at other sites, will allow us to substantially expand manufacturing over the coming years,” Lilly’s spokesperson said of the latest supply shortfall.

Looking ahead, meanwhile, Lilly expects to generate revenues between $40.4 billion and $41.6 billion in 2024. Lilly said it continues to execute on its “manufacturing agenda,” but warned that strong demand and the time required to bring full capacity online means that demand for incretins—like tirzepatide—is “likely to outpace supply in 2024.”