Obesity Drugs Surpass Cancer Immunotherapy to Become the World’s Top-Selling Medicines

Global sales of obesity treatments have surpassed those of the world’s leading cancer immunotherapy, according to industry estimates, marking a notable shift in the pharmaceutical market.

According to a report released on January 8 by Eugene Investment & Securities, citing Bloomberg consensus data, the global obesity drug market recorded approximately USD 30 billion (around KRW 44 trillion) in sales last year, reaching this level for the first time.

The report estimates that obesity drugs based on tirzepatide, developed by Eli Lilly and marketed under brands including Mounjaro, generated approximately USD 35.8 billion in estimated global sales based on consensus projections. Obesity drugs based on semaglutide, developed by Novo Nordisk and marketed under brands such as Wegovy, recorded an estimated USD 35.6 billion in global sales over the same period.

These estimates exceed the USD 31.5 billion in annual sales reported for Keytruda, the immuno-oncology drug developed by MSD (Merck). Keytruda had held the position of the world’s top-selling prescription drug since 2023. Eugene Investment & Securities estimated that sales of GLP-1–based obesity drugs exceeded Keytruda’s revenue by approximately 13–14%.

The report noted that this trend reflects a structural change in the blockbuster drug market, which has traditionally been led by cancer therapies, as treatments for obesity and metabolic diseases gain a larger share of global pharmaceutical sales.

The obesity treatment market is expanding alongside the development of new formulations. An oral version of Wegovy was launched in the United States shortly after receiving approval from the U.S. Food and Drug Administration (FDA). Eli Lilly has also submitted an FDA approval application for orforglipron, an oral obesity drug.

Novo Nordisk is conducting Phase 2 clinical trials for amicretin, a next-generation oral obesity treatment, while Structure Therapeutics plans to initiate Phase 3 clinical trials for its oral small-molecule drug aleniglipron in the second half of the year.

In addition to GLP-1 therapies, pharmaceutical companies are developing obesity treatments based on amylin, a hormone released after meals that suppresses appetite. Roche acquired rights to the amylin analog petrelintide from Zealand Pharma, while AbbVie acquired the amylin analog GUB014295 from Gubra.

Competition among Korean pharmaceutical companies is also intensifying. Ildong Pharmaceutical, Chong Kun Dang, and D&D Pharmatech are developing oral GLP-1–based obesity treatments at various stages of development. Hanmi Pharmaceutical has submitted an application to Korea’s Ministry of Food and Drug Safety for approval of a GLP-1 obesity drug intended for adults without diabetes.