Analysts flag unusually strong early demand for Mounjaro

Eli Lilly told Wall Street analysts that demand for its new diabetes drug Mounjaro (tirzepatide) was "tracking at the highest end" of the company's own expectations, according to a summary of remarks from Lilly's chief financial officer, Anat Ashkenazi, at a Morgan Stanley healthcare conference ^[1]. The drug had been approved in mid-May 2022 as an add-on to diet and exercise to help adults with Type 2 diabetes control blood sugar ^[1].

Part of that surge came from prescribing for weight loss, a use the U.S. Food and Drug Administration had not yet cleared ^[1]. Mounjaro is a once-weekly injection that activates two hormone receptors, GLP-1 and GIP, and Lilly can adjust the dose to a patient's needs ^[1]. Earlier in the summer, the drug had posted strong weight-loss results in the SURMOUNT-1 trial, meeting its main goals for both percentage of body weight lost and the share of patients who lost at least 5% of their starting weight compared with placebo ^[1].

Lilly said it was "prepared to fully supply Mounjaro" in the U.S. and planned to double its incretin manufacturing capacity — covering both Mounjaro and its older diabetes drug Trulicity — by the end of 2023 ^[1]. Even so, insurance coverage lagged behind demand. Just over 20% of prescriptions were covered by insurance at the time, meaning most patients relied on manufacturer copay cards to afford the drug, and Lilly called improving that access a "top priority" while saying it would stay disciplined about offering discounts ^[1].

Analysts also noted that most Type 2 diabetes patients switching to Mounjaro were coming from competing drugs rather than from Lilly's own Trulicity ^[1]. Outside the U.S., Lilly described a more cautious rollout, citing reported shortages of Novo Nordisk's Ozempic (semaglutide) in some markets ^[1]. Novo was separately dealing with a manufacturing problem that had constrained U.S. supply of its obesity drug Wegovy, which the company expected to resolve by the end of 2022 ^[1].

Why it matters for patients

Fast early demand combined with limited insurance coverage meant many patients seeking Mounjaro in the fall of 2022 faced high out-of-pocket costs unless they qualified for a copay card ^[1]. Because Mounjaro's approval at the time covered only Type 2 diabetes, patients using it for weight loss were doing so off-label, which can affect whether insurance will pay for it at all ^[1]. Lilly's plan to double manufacturing capacity signaled the company anticipated continued strong demand, but that expansion was not expected to be complete until the end of 2023, leaving a supply gap in the meantime ^[1]. Analysts also flagged that Mounjaro and Wegovy together could represent an obesity market worth roughly $50 billion by 2030, a sign of how much drugmakers expected demand to grow ^[1].

What happens next

Lilly's manufacturing expansion for tirzepatide and Trulicity was slated to finish by the end of 2023 ^[1]. On the obesity front, Lilly said it felt confident it could supply an early U.S. launch for weight loss in 2023 if the drug won approval, though the company's base-case plan was a 2024 launch pending additional phase 3 trial data ^[1]. Evaluate Vantage had forecast Mounjaro sales could reach $4.9 billion by 2026, a projection made before any obesity approval ^[1]. The European Medicines Agency's human medicines committee had already recommended approval for Mounjaro in Type 2 diabetes in July 2022, ahead of a formal EU authorization decision ^[1].