Pfizer drops plan for twice-daily obesity pill due to side effects

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Pfizer is abandoning its plans for a weight loss pill to be taken twice a day after trials showed it caused significant side effects, in a setback to the US drugmaker’s effort to enter the fast-growing market for obesity treatments.

Shares in Pfizer fell 4 per cent in pre-market trading in New York on Friday after the group said more than half of the participants in its clinical trial for the new drug had dropped out because of side effects. About 40 per cent of the participants taking a placebo also left the trial.

The company said last year that its oral obesity pills could generate more than $10bn in future revenues.

The mid-stage trial showed the pill, danuglipron, caused high rates of gastrointestinal side effects, with up to 73 per cent of participants taking the drug experiencing nausea and up to 47 per cent vomiting, the company said.

The drug did help participants lose as much as 13 per cent of their body weight over 32 weeks, a significant amount but less than the approved injectables from Eli Lilly and Novo Nordisk.

Novo Nordisk and Eli Lilly dominate the market for obesity treatments, which some analysts have estimated could be worth up to $140bn.

Pfizer will not take the twice-daily formulation into late-stage trials but will focus on developing a pill to be taken once a day. Mikael Dolsten, Pfizer’s chief scientific officer, said the group would aim to ease the side effects and improve its study design and execution in its future studies of the daily pill.

“We believe an improved once-daily formulation of danuglipron could play an important role in the obesity treatment paradigm,” he said.

Novo Nordisk and Eli Lilly have struggled to keep up with soaring demand for obesity treatments. Novo Nordisk sells Wegovy and Ozempic, a diabetes medicine often prescribed off-label for weight loss, while Eli Lilly recently secured approval of Zepbound, its obesity drug. Many patients taking these drugs also suffer from gastrointestinal side effects.

While injectables are the only treatments at present on the market, both companies are working on weight loss pills.

Rival pharmaceutical groups are eager to enter the market, including AstraZeneca, which recently signed a licensing deal with Chinese company Eccogene for the rights to its weight loss pill.

Separately, the European Medicines Agency said on Friday that it could not draw any causal link between the current generation of obesity drugs, known as GLP-1 agonists, and suicidal thoughts and self-harm. But the regulator said it had sent further questions to the drugmakers as part of its review announced in July.