Pfizer to end development of experimental obesity pill due to elevated liver enzymes

Pfizer on Monday said it would stop developing its experimental obesity and diabetes pill, lotiglipron, due to elevated liver enzymes in patients who took the drug once a day in midstage clinical studies. 

Those elevated enzymes often indicate damage to cells in the liver, but the pharmaceutical giant said no patients experienced liver-related symptoms or side effects. 

Shares of Pfizer closed 3.6% lower on Monday.

New York-based Pfizer said it will instead focus on its other oral obesity drug, danuglipron, which is in a fully enrolled phase two clinical trial. 

That study found that body weight was reduced after patients with Type 2 diabetes took high-dose versions of danuglipron twice a day for 16 weeks, according to results Pfizer released last month.

The company expects to finalize plans for a phase three clinical trial program on danuglipron by the end of 2023. Pfizer added that it is also developing a version of danuglipron that patients take once a day instead of twice. 

"We look forward to analyzing the danuglipron Phase 2 results and selecting the dose and titration schedule that will maximize the therapeutic benefit and safety and tolerability," William Sessa, Pfizer's chief scientific officer of internal medicine, said in a press release. 

Pfizer CEO Albert Bourla has said that an obesity pill could eventually generate $10 billion each year for the company.

Lotiglipron, danuglipron and Novo Nordisk's blockbuster weight loss injections Ozempic and Wegovy are part of a class of drugs called glucagon-like peptide-1 agonists.

They mimic a hormone produced in the gut called GLP-1, which signals to the brain when a person is full. 

The drugs can also help people manage Type 2 diabetes because they encourage insulin release from the pancreas, lowering blood sugar levels.

Oral drugs such as Pfizer's danuglipron could offer an advantage over frequent injections. Novo Nordisk and Eli Lilly are also developing their own experimental obesity and diabetes pills.

The new class of obesity drugs is piquing public interest and causing a weight loss industry gold rush. But there's still uncertainty about their accessibility, and questions remain about how long patients would need to take the drugs to keep unwanted weight off.

Some people who stop taking the drugs complain about a weight rebound that is difficult to control.

More than 2 in 5 adults have obesity, according to the National Institutes of Health. About 1 in 11 adults have severe obesity.

Analysts believe Eli Lilly’s pill has an edge over Pfizer’s danuglipron.

Wells Fargo analyst Mohit Bansal said in a research note Monday that Pfizer’s decision to compete in the oral weight loss drug space with danuglipron will be challenging given strong data on Eli Lilly’s experimental pill orforglipron. 

Overweight or obese patients who took orforglipron once a day lost 14.7% of their body weight after 36 weeks, according to midstage clinical trial results the company released Friday. 

Bansal added that physicians generally prefer a once-daily pill like orforglipron over the twice-daily danuglipron: “Based on convenience, tolerability, and weight loss magnitude, orforglipron is likely the bar to beat."