Obesity shots like Wegovy are already a cultural phenomenon. Now it’s looking like pill forms of the drugs from Eli Lilly & Co. and Novo Nordisk A/S are just as good at helping people lose weight, setting the stage for even more explosive growth in the years ahead.

Novo and Lilly’s experimental obesity pills helped people lose about 15% of body weight, similar to weight-loss shots on the market already, according to findings presented at the American Diabetes Association’s conference over the weekend. Meanwhile, Pfizer Inc. said it will discontinue one of its weight loss pills under development as safety concerns arose.

Drugmakers have been rushing to develop obesity drugs, angling for a piece of a market that some estimate will one day be worth as much as $100 billion. Novo’s Wegovy injection has been available since 2021 and Lilly’s diabetes shot Mounjaro could be cleared on the US market for obesity soon: now, the next frontier is developing easy-to-take pill versions.

Read More: Pfizer Drops as Obesity Drug Halted on Safety Concerns (1)

“Lilly and Novo remain at the forefront” in developing pill forms of weight-loss drugs, said Richard DiMarchi, an obesity researcher at Indiana University. He worked at Lilly for more than 20 years and later sold a company he founded to Novo, but has no current ties to either company. For other companies trying to catch up, “It will be hard but not impossible,” he said.

Lilly released its strongest results of any of its treatments yet in a test of retatrutide, a shot that could further boost its efforts to dominate the burgeoning obesity drug market. People with obesity shed an average of 24.2% of their body weight, about 58 pounds, on the highest dose of the drug after 48 weeks, according to a study released Monday by the New England Journal of Medicine.

All the new drugs mimic GLP-1, a hormone that makes people feel full and eat less. But each company’s pill version takes a different approach.

Novo’s oral drug is a higher dose of an approved pill, the diabetes medication Rybelsus. Adapting a drug that’s already on the market reduces the risk of a surprise safety problem, said DiMarchi.

Lilly’s pill looks safe and effective so far, but a lot will depend on what come out of larger, late-stage trials.

“It still needs to be proven that this is truly effective and truly safe for long term use,” DiMarchi said.

Pfizer Fumble

Pfizer had a setback on its road to developing an obesity pill Monday, halting development of an experimental drug called lotiglipron after seeing high levels of liver enzymes in patients on the drug. Few details are known about precisely what level of enzymes Pfizer saw. Evercore ISI analyst Umer Raffat called it a “big setback” for the company.

Pfizer is continuing to test another pill called danuglipron that outperformed a placebo in a recent study, producing around 9 more pounds of weight loss at the highest dose. “Sure they’ll move ahead with danuglipron,” Raffat said in a note to investors, “but it’s not the best shot they had.”

Experts say what happened with Pfizer’s pill isn’t a sign of trouble ahead for the other companies’ oral treatments. Still Pfizer’s shares were down as much as 5.6% Monday, as investors considered other issues with the therapy.

Danuglipron currently must be taken twice a day, and that could “prove challenging, assuming all else is equal, leaving Pfizer’s $10 billion peak sales estimate for danuglipron looking optimistic,” Bloomberg Intelligence analysts John Murphy and Mila Bankovskaia said. Pfizer said it sticks by its estimate for peak sales.

Read More: Lilly Experimental Weight-Loss Pill Gets Rapid Results in Study

The company is also looking at developing a once-daily version that could be moved into late-stage testing, a Pfizer spokesperson said.

Wall Street analysts don’t expect Lilly and Novo’s pills to have the same problems as Pfizer’s drug. And all the oral drugs are likely years away from becoming commercially available. But major differences already emerging between the two could set Lilly’s medicine up for greater success.

Lilly’s pill, for instance, helped patients lose as much as 15% of their body weight after around eight months of treatment. Longer use could help patients slim down even more, perhaps losing as much as 20% of their body weight, said Daniel Drucker, a co-discoverer of the GLP-1 hormone who’s a professor of medicine at the University of Toronto.

Drucker called the drug “the star of the show” at the conference. He said it was unprecedented for a pill to produce so much weight loss so quickly.

‘Thumbs Up’

“In terms of hot new data that was not previously disclosed before, thumbs up to Lilly,” he said.

Read More: Lilly’s Mounjaro Gives Positive Results in Obese Diabetic People

The Lilly medication also helped reduce levels of certain liver enzymes, Bloomberg Intelligence analyst Michael Shah said. It’s difficult to compare its findings with Pfizer’s given the lack of detail in company releases.

Novo’s drug, meanwhile, has other limitations. Oral semaglutide uses high doses of a main ingredient, so it’s likely to be harder and more expensive to manufacture large amounts. Also, in studies of Novo’s pill, patients had to fast before taking the drug and then a half an hour afterwards, issues that don’t affect Lilly’s pill.

--With assistance from Nacha Cattan.

(Updates with Lilly study in fifth paragraph.)

Author: Emma Court, Robert Langreth and Matthew Griffin