Keytruda Hangs On to Best Seller Crown as GLP-1s Gain Ground

Why It Matters

The shift signals a fundamental re‑ranking of blockbuster therapies, with obesity drugs reshaping revenue streams and competitive dynamics across oncology and metabolic markets.

Key Takeaways

• Keytruda $31.7B sales, 7% YoY growth 2025.
• GLP‑1 franchises total $36.5B, surpassing Keytruda.
• Lilly’s tirzepatide sales nearly double, $36.5B total.
• Novo faces compounding and pricing pressures, loses rank.
• Merck launches subcutaneous Keytruda Qlex, $40M first-year sales.

Pulse Analysis

The 2025 pharmaceutical landscape underscores a watershed moment: immuno‑oncology’s long‑standing champion, Merck’s Keytruda, is being outpaced by the meteoric rise of GLP‑1 agents. While Keytruda’s $31.7 billion haul reflects robust demand across more than 40 indications, the combined $36.5 billion revenue of Eli Lilly’s tirzepatide and Novo Nordisk’s semaglutide products illustrates how weight‑loss and diabetes therapies have become the new mega‑blockbusters. Analysts attribute this shift to expanding clinical evidence, payer acceptance, and a growing consumer focus on obesity management, positioning GLP‑1s as the growth engine for the next decade.

Looking ahead, the GLP‑1 sector is poised for an "acceleration" phase in 2026, driven by oral formulations such as Lilly’s orforglipron and Novo’s oral Wegovy, which promise broader patient access and adherence. These innovations, coupled with aggressive market execution, are expected to push tirzepatide and semaglutide families toward $100 billion in peak sales. Meanwhile, Merck is hedging against impending loss‑of‑exclusivity by introducing Keytruda Qlex, a subcutaneous delivery that could capture up to 40 % of the injectable market by 2028, and by expanding its oncology pipeline to sustain revenue beyond the biosimilar horizon.

The competitive dynamics extend beyond sales figures. Patent cliffs, compounding challenges, and pricing negotiations are reshaping strategies across the board. Novo Nordisk’s struggle with compounders and U.S. price concessions highlights the fragility of first‑mover advantage, while AbbVie’s successful transition from Humira to Skyrizi demonstrates how diversification can mitigate cliff risks. For investors and industry leaders, the message is clear: agility in product formulation, pipeline development, and market access will determine which blockbuster portfolios thrive in an era where obesity therapeutics are redefining the definition of a mega‑blockbuster.