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Breaking News on Tirzepatide – the Most Buzzworthy Drug in Development

Published: 3/5/21
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By Eliza Skoler, Matthew Garza, Ursula Biba, and Rhea Teng

Drug company Lilly released important results showing that the new therapy may be extremely effective for people with type 2 diabetes. Across three clinical trials, tirzepatide reduced A1C by an average of 2.5 percentage points and led to a weight loss of about 25 pounds.

New results from a clinical trial on tirzepatide were released just this week, showing similar findings to those released in February. Together, the results from all three clinical trials show that the new type 2 diabetes drug can lead to a sizeable A1C reduction, significant weight loss of about 25 pounds, and less hypoglycemia compared to insulin and GLP-1 agonist medication among people with type 2 diabetes. Tirzepatide combines the activity of two types of drugs into a once-weekly injectable medication. This new glucose-lowering therapy is called a “dual GIP and GLP-1 receptor agonist” and is currently in development to help people manage type 2 diabetes. 

The two previous trials, referred to as SURPASS-3 and SURPASS-5, included almost 2,000 participants with type 2 diabetes who took different doses of tirzepatide, insulin, or placebo medication. The latest results come from SURPASS-2, which included an additional 1,879 participants with type 2 diabetes who injected weekly doses of tirzepatide or semaglutide, the current "state of the art" GLP-1 agonist. The three trials investigated 5 mg, 10 mg, and 15 mg doses of tirzepatide over 40 or 52 weeks, and found that all doses led to impressive reductions in A1C and body weight.

Among participants taking 15 mg of tirzepatide, alongside strong lifestyle advice:

  • A1C levels went down nearly 2.5 percentage points from a starting point above 8%.

  • Average weight loss was 25 pounds.

The change in A1C was particularly important. About half of all participants taking the 15 mg dose of tirzepatide across both trials achieved an A1C level below 5.7% – this is the level seen in individuals without diabetes. Among participants taking any dose of tirzepatide across the three trials, more than 80% achieved an A1C below 7%, and at the highest dose of tirzepatide more than 90% saw this result. 

Here’s what the three clinical trials studied:

  • SURPASS-3 was a 52-week randomized, open-label trial, that compared the effects of tirzepatide to insulin degludec in adults with type 2 diabetes. At baseline, participants had an average duration of diabetes of eight years, an A1C of 8.2%, and weighed 207 lbs.

  • SURPASS-2 was a 40-week head-to-head clinical trial that compared tirzepatide to GLP-1 agonist semaglutide (in addition to metformin) in adults with type 2 diabetes. At baseline, participants had an average duration of diabetes of nine years, an A1C of 8.3%, and weighed 207 lbs.

  • SURPASS-5 was a 40-week, randomized, double-blind trial, that studied the effects of tirzepatide compared to a placebo in addition to insulin glargine (with or without metformin use) in adults with type 2 diabetes. At baseline, participants had an average duration of diabetes of 13 years, an A1C of 8.3%, weighed 209 lbs, and took 38 daily units of insulin.

Hypoglycemia (low blood sugar) has historically been a concerning side effect of new diabetes therapies, particularly with mealtime insulin and sulfonylureas (SFUs). GLP-1 and GIP drugs generally do not have this complication if taken without mealtime insulin or SFUs. In SURPASS-2, participants experienced almost no hypoglycemia. Even in SURPASS-3 (which included insulin) the tirzepatide group experienced less than one hour a day of hypoglycemia; those on insulin degludec showed almost seven times more hypoglycemia each day. Additional side effects were primarily gastrointestinal; people taking tirzepatide did experience more nausea and diarrhea in both trials, at levels comparable to those of currently available GLP-1 drugs.

These results are both exciting and promising, and we look for tirzepatide to be submitted to the FDA and regulatory agencies across the world for approval next year. In the meantime, we’ll continue to keep you updated as more results are released.

Editor’s note: our news on tirzepatide and the SURPASS-3 and SURPASS-5 trials was first published on February 17, 2021. More news came out on SURPASS-2 and we updated the piece on March 5 to include the results.

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