FDA approves Mounjaro, first dual-hormone diabetes drug from Eli Lilly
Mounjaro gives adults with type 2 diabetes a new once-weekly option that lowered A1C more than several comparators, but it is not approved for weight loss and carries a boxed thyroid warning.
The FDA approved Mounjaro (tirzepatide) on May 13, 2022, making it the first US-approved diabetes drug that activates receptors for two hormones, GIP and GLP-1, instead of one [1]. Eli Lilly's once-weekly injection is cleared for adults with type 2 diabetes as an addition to diet and exercise [1]. It is not indicated for weight loss [1].
Mounjaro will be sold in six once-weekly dose strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg, in an auto-injector pen with a pre-attached, hidden needle [1]. Lilly said the drug is expected to be available in the United States "in the coming weeks" and that it plans a savings card for people who qualify [1]. A company spokesperson said Lilly has not announced a price [2].
The approval rests on the phase 3 SURPASS program, which included five global registration trials lasting 40 to 52 weeks, plus two regional trials in Japan [1]. The studies tested Mounjaro 5 mg, 10 mg and 15 mg, used alone and with commonly prescribed diabetes medicines including metformin, SGLT2 inhibitors, sulfonylureas and insulin glargine [1]. Comparators included injectable semaglutide 1 mg, insulin glargine and insulin degludec [1].
Across the trials, participants' A1C fell by an average of 1.8% to 2.1% on the 5 mg dose and 1.7% to 2.4% on the 10 mg and 15 mg doses [1]. In SURPASS-2, which enrolled adults whose blood sugar was not controlled on metformin alone, A1C fell 2.0% on 5 mg, 2.2% on 10 mg and 2.3% on 15 mg, compared with 1.9% on semaglutide 1 mg [1]. In that same trial, average body weight fell 17 lb, 21 lb and 25 lb on the three Mounjaro doses, compared with 13 lb on semaglutide [1].
Weight change was a key secondary endpoint in all of the SURPASS studies, not the main measure, and Mounjaro is not indicated for weight loss [1]. Averaged across the program, participants lost between 12 lb on 5 mg and 25 lb on 15 mg [1]. BioPharma Dive reported that advisers to the Institute for Clinical and Economic Review, an independent drug cost watchdog, found there was not sufficient evidence to prove Mounjaro provides a significant health benefit over Ozempic, Novo Nordisk's semaglutide shot [2].
Common side effects reported in at least 5% of patients included nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion and stomach pain [1]. The label carries a boxed warning about thyroid C-cell tumors seen in rodents, and the drug is contraindicated in people with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2 [1]. Other listed risks include pancreatitis, low blood sugar, serious allergic reactions, kidney problems, severe stomach problems, vision changes and gallbladder problems [1]. Mounjaro has not been studied in people with a history of pancreatitis and is not for people with type 1 diabetes; whether it is safe and effective in children under 18 has not been established [1].
Why it matters for patients
Mounjaro adds a new mechanism to the type 2 diabetes options already on the market, and it is the first new class of diabetes medicine introduced in nearly a decade, according to Lilly [1]. The company says more than 30 million Americans live with type 2 diabetes and about half are not reaching their target blood glucose levels [1].
Two details may shape what happens at the pharmacy and in the clinic. First, the approval covers blood sugar control only, so coverage for weight loss is a separate question that has not been settled [1]. Second, because of the boxed warning and the contraindication, people with a personal or family history of medullary thyroid carcinoma or with MEN 2 are not candidates for the drug [1]. Gastrointestinal side effects are the most common, similar to other medicines in this class [1][2].
What happens next
Lilly has said Mounjaro will reach US pharmacies in the coming weeks, with a savings card planned for people who qualify [1]. Pricing has not been disclosed [2]. Tirzepatide is also under regulatory review for type 2 diabetes in Europe, Japan and several additional markets, with no decision dates reported [1]. Novo Nordisk is testing a dual-acting competitor to Mounjaro, but that program is only in phase 2 testing, well behind Lilly's drug [2].
Sources
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