- Pfizer will not advance a twice-daily dose of an experimental obesity drug into further testing after results from a mid-stage study showed high rates of gastrointestinal side effects and participant dropout.
- Treatment did lead to significant weight loss compared to placebo over the course of the Phase 2b study. Placebo-adjusted reductions in body weight ranged from 8% to 13% at 32 weeks, Pfizer said in a statement Friday. Discontinuation rates were more than 50% on some drug doses, however.
- Moving forward, Pfizer will turn its focus to a once-daily version that’s currently being tested in a study meant to determine how the drug’s processed by the body. Data are expected in the first half of next year.
Pfizer’s drug, known as danuglipron, is a GLP-1 agonist like in-demand obesity treatments from Novo Nordisk and Eli Lilly. But unlike those drugs, which are injections, danuglipron is taken orally, an advantage in convenience that Pfizer hopes will help it break into the fast-growing market.
The data released Friday are a significant blow to those hopes, particularly after Pfizer stopped testing of another experimental obesity pill in June. Shares in the drugmaker fell by more than 6% in Friday morning trading, representing a drop in market capitalization of about $10 billion.
Louise Chen, an analyst at Cantor Fitzgerald, described the data as “disappointing” in a note to clients. According to Chen, investors were hoping to see a placebo-adjusted weight reduction of around 14% to 15%, which physicians Cantor has polled said would be enough to merit switching from injectable drugs like Novo’s Wegovy.
Pfizer didn’t break out adverse event rates by danuglipron dose tested, but said up to 73% of participants experienced nausea, up to 47% vomiting and up to 25% diarrhea. The side effects were generally mild, the company said.
Notably, danuglipron wasn’t associated with signs of liver toxicity, which was the reason Pfizer had scrapped its other experimental pill, called lotiglipron.
“We believe an improved once-daily formulation of danuglipron could play an important role in the obesity treatment paradigm, and we will focus our efforts on gathering the data to understand its potential profile,” said Mikael Dolsten, Pfizer’s top scientist and head of R&D, in the company’s statement.
Results from the ongoing pharmacokinetic trial of the once-daily version will “inform a potential path forward,” Dolsten added.
Another setback could put Pfizer in the uncomfortable position of falling further behind in a fiercely competitive development race. Lilly, which recently won U.S. approval of its GLP-1 weight loss drug Zepbound, is also developing an oral obesity medicine called oforglipron that showed promise in a mid-stage trial earlier this year.
Pfizer’s CEO Albert Bourla has said he expects the market for GLP-1 drugs, which are also used to treat Type 2 diabetes, to eventually reach $90 billion in sales. He estimated oral versions could claim about one-third of that figure.