Pharmaceutical giant Pfizer announced Monday it will discontinue development of its experimental weight loss medication danuglipron after discovering a potential case of liver damage in one of its study participants. This marks the company’s second abandoned obesity pill since 2023, dealing another blow to its ambitions in the increasingly competitive weight loss drug market.
The decision comes as Pfizer faces mounting challenges in its pursuit to compete with market leaders Eli Lilly and Novo Nordisk, both of which currently have oral obesity medications in Phase 3 clinical trials. The oral weight loss drug market represents a potentially lucrative alternative to injectable obesity medicines, which generated $13 billion in combined sales last year.
Danuglipron’s development journey has been tumultuous for Pfizer. Earlier testing of a twice-daily version revealed high rates of adverse effects in Phase 2 studies, though the company remained optimistic about a once-daily formulation’s potential. CEO Albert Bourla had previously expressed confidence that Pfizer could become the second company, after Lilly, to bring an obesity pill to market.
According to Pfizer’s chief scientist Chris Boshoff, while the frequency of elevated liver enzymes observed in danuglipron trials was comparable to other obesity medications, the combination of clinical trial data, the liver damage case, and recent regulatory feedback led to the decision to halt development. Despite expressing
disappointment, Boshoff affirmed the company’s commitment to advancing promising therapeutic programs.
Pfizer maintains other obesity drug candidates in its pipeline, including a Phase 2 pill targeting the gut hormone GIP and a Phase 1 GLP-1 drug being developed in partnership with Nxera Pharma. The company also continues to explore potential obesity treatments through its collaboration with startup incubator Flagship Pioneering.
The setback has prompted Wall Street analysts to speculate that Pfizer might pursue acquisitions to strengthen its obesity drug portfolio, particularly if its remaining pipeline candidates share structural similarities with danuglipron. This speculation drove up stock prices for several companies developing weight loss treatments, including Viking Therapeutics, Altimmune, Structure Therapeutics, and Metsera.
Viking Therapeutics has both injectable and oral obesity medications in advanced development stages, while Altimmune recently reported promising Phase 2 results for its dual-acting treatment. Structure Therapeutics shared positive Phase 2 data in the previous year, and Metsera successfully raised $275 million in an initial public offering this January, buoyed by strong data from its long-acting GLP-1 injection development program.
The market for obesity treatments has become increasingly competitive as pharmaceutical companies race to develop alternatives to existing injectable medications. The development of oral weight loss drugs represents a particularly attractive opportunity, as they could offer patients a more convenient treatment option compared to current injectable therapies.
Pfizer’s withdrawal from danuglipron development reflects the significant challenges pharmaceutical companies face in bringing new obesity treatments to market, particularly regarding safety concerns and regulatory requirements. The decision also highlights the intense competition in the obesity drug sector, where companies must carefully balance the potential rewards of market entry against the risks and challenges of drug development.
While this represents a significant setback for Pfizer’s obesity drug program, the company’s continued investment in alternative candidates and potential for strategic acquisitions suggests it remains committed to establishing a presence in this rapidly growing therapeutic area.
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