Pfizer has said an experimental weight loss injection taken once a month has shown encouraging results in a mid-stage clinical trial, as competition grows in the fast-expanding obesity drug market.
The US pharmaceutical company said on Tuesday that adults with obesity who received the drug lost up to 12.3% of their body weight after 28 weeks. People who received a placebo did not see similar results.
The drug, known as PF-08653944, belongs to a class of medicines called GLP-1 receptor agonists. These drugs work by reducing appetite and slowing digestion. Similar medicines are already widely used for weight loss and diabetes.
Pfizer said the trial showed no clear slowing, or plateau, in weight loss by week 28. This suggests that patients may continue to lose weight as the study runs on to week 64.
Albert Bourla, Pfizer’s chief executive, said the early results were “very good” and highlighted the benefits of a monthly injection.
“We have a monthly product that has a very competitive profile in terms of both how well it works and how well people tolerate it,” he said.
The company said side effects were similar to those seen with other GLP-1 drugs already on the market. Most were described as mild or moderate, with nausea and vomiting the most common. Pfizer said there was no more than one case of severe nausea or vomiting in any dose group.
A total of 108 patients took part in two treatment groups in the trial. Ten people stopped taking the drug because of side effects.
Dr Jim List, Pfizer’s chief internal medicine officer, said the results supported further testing of the drug as a monthly treatment.
He added that Pfizer plans to include a higher monthly dose in the next phase of trials, known as phase 3, which involve larger numbers of patients and are needed before a drug can be approved.
The drug was developed by Metsera, a company that Pfizer bought last year after a bidding contest with rival Novo Nordisk.
Despite the positive results, Pfizer faces strong competition in the weight loss drug market. Several other companies are developing similar treatments, including monthly injections.
Amgen, a US biotechnology firm, is testing a monthly weight loss injection called MariTide and has several late-stage trials under way.
Two major players, Eli Lilly and Novo Nordisk, already dominate the market and are working on newer and more powerful treatments. These include both injections and daily pills.
In December, Eli Lilly said its experimental drug retatrutide led to greater weight loss than any existing obesity treatment in a late-stage trial. Patients taking the highest weekly dose lost an average of up to 71.2 pounds over 68 weeks.
Analysts say demand for weight loss drugs is expected to grow rapidly, but questions remain about long-term safety, access and cost. Pfizer’s latest results add to the growing evidence that monthly injections could become another option for patients in the years ahead.