Experimental obesity drug yields 22% weight loss

An experimental drug has enabled people with obesity or who are overweight to lose about 22.5% of their body weight, about 52 pounds on average, in a large trial, the drug’s maker announced.

The company, Eli Lilly, has not yet submitted the data for publication in a peer-reviewed medical journal or presented it in a public setting. But the claims released last week nonetheless amazed medical experts. “Wow (and a double Wow!)” Dr. Sekar Kathiresan, CEO of Verve Therapeutics, a company focusing on heart disease drugs, wrote in a tweet. Drugs like Eli Lilly’s, he added, are “truly going to revolutionize the treatment of obesity!!!”

Kathiresan has no ties to Eli Lilly or to the drug.

Dr. Lee Kaplan, an obesity expert at Massachusetts General Hospital, said that the drug’s effect “appears to be significantly better than any other anti-obesity medication that is currently available in the U.S.” The results, he added, are “very impressive.”

Kaplan who consults for a dozen pharmaceutical companies, including Eli Lilly, said he was not involved in the new trial or in the development of the drug.

On average, participants in the study weighed 231 pounds at the outset and had a body mass index, or BMI — a commonly used measure of obesity — of 38. (Obesity is defined as a BMI of 30 and higher.)

At the end of the study, those taking the higher doses of the Eli Lilly drug, called tirzepatide, weighed about 180 pounds and had a BMI just below 30, on average. The results far exceed those usually seen in trials of weight loss medications and are usually seen only in surgical patients.

Some trial participants lost enough weight to fall into the normal range, said Dr. Louis Aronne, director of the comprehensive weight control program at Weill Cornell Medical Center in New York, who worked with Eli Lilly as the study’s principal investigator.

Most of the people in the trial did not qualify for bariatric surgery, which is reserved for people with a BMI over 40, or those with a BMI from 35 to 40 with sleep apnea or Type 2 diabetes. The risk of developing diabetes is many times higher for people with obesity than for people without it.

An Eli Lilly spokesperson said the company did not have a public timeline for seeking approval of the drug with the Food and Drug Administration.

Because obesity is a chronic medical condition, patients would need to take tirzepatide for a lifetime, as they do for blood pressure or cholesterol drugs, for example.

Dr. Robert Kushner, an obesity expert at Northwestern University’s Feinberg School of Medicine in Chicago and a paid consultant to Novo Nordisk, said the new drug along with a similar but less effective one by Novo Nordisk, can close a so-called treatment gap.

Diet and exercise, combined with earlier obesity drugs, usually yield perhaps a 10% weight loss in patients. That is enough to improve health, but not nearly enough to make a big difference in the lives of people who are obese.

The only other treatment is bariatric surgery, which can result in substantial weight loss. But many people are ineligible or simply do not want the surgery.

With the Eli Lilly drug and Novo Nordisk’s semaglutide, which was recently approved, “we really are on the cusp of a new way of treatment,” Kushner said.

But prices may be a barrier. Insurers often will not pay for weight loss drugs. The Novo Nordisk drug, whose brand name is Wegovy, has a list price of $1,349.02 per month.

Experts worry that tirzepatide, if approved, might carry a price in the same range. Many people who could most benefit from weight loss may be unable to afford such expensive drugs.

The Eli Lilly study lasted 72 weeks and involved 2,539 participants. Many qualified as obese, while others were overweight but also had such risk factors as high blood pressure, high cholesterol levels, cardiovascular disease or obstructive sleep apnea.

Dr. Nadia Ahmad, senior medical director of Eli Lilly’s obesity program, said that seeing the results was an emotional moment for her.

“I don’t think I ever imagined we could reach this degree of weight loss with a medicine,” she said.