An experimental Eli Lilly diabetes drug outperformed a long-acting form of insulin in a key clinical trial, strengthening the case that the treatment could become a successor to the company’s blockbuster seller Trulicity.
The Lilly drug, tirzepatide, led to superior reductions in both A1C, which is a measure of blood sugar, and body weight. Those reductions were reported across all three doses tested in the Phase 3 clinical trial, the last in a series of large, registrational studies. With the data in hand, Lilly said it is now preparing to seek regulatory approval later this year.
Tirzepatide has two components. The first is glucose-dependent insulinotropic polypeptide (GIP), a hormone that stimulates the secretion of insulin. The second part is a glucagon-like peptide 1 receptor agonist (GLP-1), which stimulates insulin secretion. This component also slows the emptying of food from the stomach to the small intestine, which in turn reduces a person’s food intake. Lilly’s Trulicity, a GLP-1 agonist, is the company’s top-selling product generating more than $5 billion in sales last year. Tirzepatide, a once-weekly injectable drug, combines the GIP and GLP-1 mechanisms into a single molecule.
The latest Phase 3 test for tirzepatide was an open-label study enrolling more than 2,000 people with type 2 diabetes. Those participants had an increased cardiovascular risk and were receiving treatment with oral drugs that reduce blood glucose levels. All of the patients in the treatment arms of the study started at a 2.5 mg dose, which increased every four weeks until reaching the randomized maintenance dose.
At the highest dose, the Lilly drug led to a 2.58% reduction in A1C and a body weight reduction of 13% (11.7 kg, 25.8 pounds) after 52 weeks. By comparison, those treated with long-acting insulin saw a 1.44% reduction in A1C and a 2.2% weight gain (1.9 kg, 4.2 pounds). Completion of the study was driven by the accrual of major cardiovascular events, which is a requirement for evaluating cardiovascular risk for type 2 diabetes drugs. Once the program reached a predefined number of these events, a cardiovascular analysis was conducted.
Lilly said that the overall safety of tirzepatide was consistent with the GLP-1 receptor agonist drug class in this patient population. The most common side effects were gastrointestinal, and they usually occurred in the dose escalation period and then decreased over time. Though the main goal of the study was measured at 52 weeks, many study participants continued longer, some for up to two years.
The latest study was the largest and longest clinical trial for tirzepatide, which Lilly said has been tested in more than 13,000 patients across 10 clinical trials. Five of those trials were large global studies designed to support registration of the drug. Lilly said it plans to submit the full registration package to regulators by the end of 2021.