FDA Approves Eli Lilly's Tirzepatide for T2D

The FDA today approved Eli Lilly’s tirzepatide for patients with type 2 diabetes (T2D). The treatment, to be sold as Mounjaro, is a novel, dual targeted, glucagon-like peptide-1 (GLP-1) receptor agonist that has been shown to improve glycemic control in this patient population when added to diet and exercise.

The treatment had previously received a priority review designation from the FDA.

T2D is the most common form of the disease and currently affects over 30 million Americans. “Today’s FDA approval underscores our commitment to the discovery and development of new treatment pathways, and we are thrilled to bring this new and innovative treatment option to people living with T2D,” said Mike Mason, president, Lilly Diabetes, in a statement.

Tirzepatide activates the GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptors, which both play a role in blood sugar control, and is administered via injection once-weekly. Doses can be adjusted to meet individual patients' blood sugar goals while 3 doses (5 mg, 10 mg, and 15 mg) were assessed in the 5 clinical trials supporting the approval.

Tirzepatide’s efficacy was compared with a placebo, the GLP-1 receptor agonist semaglutide, and 2 long-acting insulin analogues. Those randomized to 15 mg of the study treatment as a standalone therapy exhibited a 1.6% lower glycated hemoglobin (A1C) on average compared with those who received a placebo. When compared with those who received a placebo plus a long-acting insulin, A1C decreased by 1.5% on average among those taking tirzepatide.

“Patients who received the maximum recommended dose of Mounjaro had lowering of their HbA1c by 0.5% more than semaglutide, 0.9% more than insulin degludec and 1.0% more than insulin glargine,” according to the press release.

Common adverse effects associated with tirzepatide include nausea, vomiting, diarrhea, and decreased appetite, among others. As the treatment was shown to cause thyroid C-cell tumors in rats, its indication precludes treatment for patients with a family history of medullary thyroid cancer or those with Multiple Endocrine Neoplasia syndrome type 2.

Study participants had an average body mass index of 32 to 34 kg/m², while those randomized to 15 mg tirzepatide alone saw an average weight loss of 15 pounds more than placebo. When taken with insulin, those taking tirzepatide saw an average loss of 23 pounds more than those on placebo and insulin, while patients receiving insulin without tirzepatide tended to gain weight throughout the study period.

In addition, average weight loss with 15 mg of tirzepatide “was 12 pounds more than semaglutide, 29 pounds more than insulin degludec and 27 pounds more than insulin glargine.”