The full results of Eli Lilly's Phase 3 clinical trial for its new experimental weight-loss drug were published in the New England Journal of Medicine and presented at the American Diabetes Association's (ADA) annual meeting on Saturday—and researchers say the results represent "a new era for obesity treatment."

'This trial gave me back my life'

In Eli Lilly's SURMOUNT-1 clinical trial, its experimental obesity drug—a weekly injection called tirzepatide—helped clinical trial patients lose roughly one-fifth of their body weight.

On average, trial participants who received the two highest doses of the drug and followed a diet and exercise program lost an average of around 52 pounds during the 72-week trial. In comparison, participants who followed the same diet and exercise plan with a placebo lost just five pounds on average.

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In August 2019, Mary Bruehl, a 63-year-old woman with diabetes and fatty liver disease from Norman, Oklahoma, joined the tirzepadite trial after she learned weight loss was a potential side effect of the drug. According to Bruehl, after "doing everything right" for years, her diabetes and weight management had faltered.

Bruehl was nearly immobilized by a hip replacement, which led to weight gain and low energy levels. "It just seemed like there wasn't anything I could do to get it off," said Bruehl. "My stomach didn't know an end to all the food in the world."

When she started taking tirzepatide in September of 2019, she lost between five and 10 pounds a month, losing almost 60 pounds by July 1, 2020, and giving her one of the best results reported from the drug.

According to Bruehl, the more weight she lost, the better she felt. As she lost more weight, she was able to resume hiking and other physical activities, which helped her feel even better.

In addition, tirzepatide prevented her from overeating. In fact, if she ate too much, the food would come back up. "I've learned to stop before I get that feeling," Bruehl said. 

After each of her weekly injections of tirzepatide, Breuhl experienced just one negative side effect: nausea. However, she was able to quickly resolve the issue with an anti-nausea pill in the morning. 

Notably, Bruehl no longer needed to take metformin for her diabetes, and her fatty liver had been resolved.

The biggest challenge Bruehl faced was adjusting to how differently she was treated after she lost the weight. "I went to some counseling about body image and to work through some of the issues I was having," she said, noting that she needed time to accept what she saw in the mirror and to stop reacting with anger to remarks about her body. "It took a little while to get comfortable in my own skin again."

"I feel more well-rounded. I feel like I'm more myself now," she said. "This trial gave me back my life."

'A new era for obesity treatment'

On May 13, FDA approved tirzepatide, under the trade name Mounjaro, to treat Type 2 diabetes.

While the drug is not currently available for weight loss, Jeff Emmick, VP of product development for the diabetes division of Eli Lilly, said the company hopes to have an updated timeline from FDA this year.

According to Robert Gabbay, ADA's chief scientific and medical officer, the trial participants' weight loss of 15% to over 20% could change the way doctors treat diabetes, shifting from a focus on reducing blood sugar to aiming for total remission.

Notably, a previous study of tirzepatide in diabetes showed that about half the participants who were early in the onset of diabetes went into remission while they were taking the drug. 

"That is a potential game changer in how we think about therapy for people with Type 2 diabetes," Gabbay said.

However, Gabbay noted that researchers do not know whether remission achieved through tirzepatide will help reduce the common complications associated with diabetes, including cardiovascular disease, nerve and kidney damage, and limb amputations.

In addition, it is not clear whether the drug will provide the same cardiovascular benefits as other weight loss drugs, such as semaglutide, noted David Rind, a primary care physician and CMO for the Institute for Clinical and Economic Review. 

According to Rind, it would be helpful to conduct a head-to-head trial between tirzepatide and semaglutide to determine whether there are any differences in their health benefits.

"The question is, is tirzepatide a step better than all those (other weight loss) drugs?" Rind said. "There's certainly reason to think it might be, but I don't think it's been proven yet."

Still, according to study author Ania Jastreboff of the Yale University School of Medicine, "[t]hose medications are much more highly effective than any other medications we've had for the treatment of obesity right now. They are clearly exceeding the greater than or equal to 5% weight reduction target."

"What we really need to focus on is [that] this is a new era for our patients; this is a new era for physicians caring for patients with obesity -- which is all of us -- and we now have the tools, and will have more tools going forward, to be able to treat our patients with obesity," she said.

"This is a new era for obesity treatment," Jastreboff added. "There were first-generation medicines, second-generation medicines, which were about 2010 to 2020. Starting last year with semaglutide [Wegovy] and now tirzepatide, this is a new era for obesity treatment." (Weintraub, USA Today, 6/5; Monaco, MedPage Today, 6/5)