

A Chinese-made antibody-drug conjugate just supercharged Keytruda in a landmark lung cancer trial, cutting the risk of progression by 65%. It's the first ADC-immunotherapy combo to win in frontline lung cancer, and it could reshape Merck's entire post-patent strategy.
Keytruda is the best-selling cancer drug on the planet. It brought in $29.5 billion for Merck last year alone, accounting for roughly 51% of the company's pharma revenue. But its core U.S. patent expires in late 2028, and cheaper copycats are already lining up at the door.
So Merck has been on a frantic shopping spree for partners that can extend Keytruda's reign. And one of those bets is paying off.
The answer: oh yes.
In a phase 3 trial called OptiTROP-Lung05, researchers tested what happens when you pair Keytruda with a Chinese-made antibody-drug conjugate (ADC) called sacituzumab tirumotecan, or sac-TMT for short. Think of an ADC as a guided missile: an antibody that locks onto cancer cells and delivers a toxic payload directly inside them, sparing healthy tissue.
The trial enrolled patients with advanced lung cancer (specifically, PD-L1-positive, EGFR/ALK-negative non-small cell lung cancer) who had never been treated before. Half got Keytruda alone. Half got Keytruda plus sac-TMT.
The combo cut the risk of cancer progression or death by 65%. The hazard ratio was 0.35, with a p-value below 0.0001. In plain English: the statistical confidence here is about as strong as it gets.
Patients on Keytruda alone saw a median progression-free survival (PFS) of 5.7 months. The combo group? Their median PFS hasn't even been reached yet, because so many patients are still doing well. The fact that it's still climbing is a very good sign.
This is the first time an ADC-plus-immunotherapy combination has won a phase 3 trial in frontline lung cancer. That's not a minor footnote; it's a potential paradigm shift.
For years, oncologists have debated the best way to improve on checkpoint inhibitors like Keytruda in the first-line setting. Two competing strategies have emerged: pair Keytruda with drugs that block blood vessel growth (VEGF-targeting agents), or pair it with ADCs that deliver chemotherapy straight to tumor cells.

A Suzhou biotech just raised $80 million on the Hong Kong Stock Exchange to fight bacterial infections, an area most investors won't touch. Its lead drug crushed the standard of care for H. pylori in Phase III, and the company's hybrid chemistry platform could reshape how we treat everything from stomach bugs to infected hip implants.


Join thousands of biotech professionals who start their day with our free, daily briefing.
This trial just handed the ADC camp a very loud megaphone.
Analysts noted the result could reshape how doctors treat PD-L1-positive lung cancer. Instead of giving Keytruda by itself and waiting to see if it works, physicians may soon have the option to hit tumors harder from day one. It's the difference between sending in a single striker and deploying the whole front line.
Sac-TMT was invented by Kelun-Biotech, a subsidiary of Sichuan Kelun Pharmaceutical in China. It targets a protein called TROP2 on the surface of cancer cells, then delivers a potent topoisomerase I inhibitor (a type of chemo drug) inside them. The drug has a clever linker design that keeps it stable in the bloodstream but releases its toxic payload once it gets inside tumor cells.
Merck didn't just license this one drug. The company has built a multi-billion-dollar ADC partnership with Kelun that spans at least ten separate assets. The relationship started back in 2021 with a $47 million upfront deal for sac-TMT. By December 2022, Merck had signed a mega-deal covering seven additional preclinical ADCs: $175 million upfront, with milestone payments that could theoretically reach $9.3 billion.
Across all their agreements, headline milestone potential exceeds $10 billion. Even if only a fraction of that gets paid out, it's a massive bet on Chinese ADC innovation.
And Merck isn't alone. Bristol Myers Squibb paid $800 million upfront for a Chinese ADC. GSK, AstraZeneca, and Roche all signed their own deals. By 2025, China represented approximately one-third of global licensing spend.
The era of dismissing Chinese biotech as a "copycat" industry is officially over.
Zoom out, and you can see why Merck is playing this game so aggressively. The company faces a $29.5 billion revenue cliff when Keytruda loses patent protection. Biosimilar developers like Celltrion, Samsung Bioepis, and Amgen are already building their knockoff versions. Analysts project Keytruda sales could drop roughly 19% by 2029.
Merck's playbook has three parts. First, launch a subcutaneous version of Keytruda (called Keytruda Qlex, which received FDA approval in September 2025) that's more convenient than the current IV infusion. Second, keep expanding Keytruda into new cancer types. Third, and most importantly, create combination regimens that carry their own patent protection.
That third strategy is where sac-TMT fits perfectly. If Keytruda plus sac-TMT becomes a standard first-line treatment for lung cancer, the combination itself could enjoy years of exclusivity even after the standalone Keytruda patent expires. Biosimilar makers can copy Keytruda, but they can't replicate a patented combination regimen overnight.
It's like owning the recipe for a famous burger. When your patent on the bun expires, you don't just shrug; you create a signature sauce that makes people want the whole meal.
Before anyone gets too excited, there's a significant caveat: overall survival data aren't mature yet. In oncology, progression-free survival is important, but it's not the finish line. Regulators, payers, and doctors all want to know if patients actually live longer, not just whether their tumors stay quiet for more months.
The early trend on overall survival is positive, but the numbers need more time to develop. Analysts also want to see how the safety profile holds up, whether the benefit is consistent across different PD-L1 levels, and how global regulators (not just China's NMPA, which is already reviewing the data on a priority basis) respond.
The trial was conducted primarily in China, so questions about global applicability will linger until broader datasets arrive.
Merck placed a multi-billion-dollar bet that Chinese ADC technology could supercharge its crown jewel. The first big phase 3 readout suggests that bet is looking very smart. A 65% reduction in progression risk is the kind of number that turns heads at oncology conferences and on trading floors alike.
The real test comes when overall survival data mature. But for now, Merck has something it desperately needed: a credible answer to the question of what comes after Keytruda's patent expires. Turns out, the answer might be a better version of Keytruda itself.
Isomorphic Labs, the Google DeepMind spinoff, just raised $2.1 billion in the largest AI drug discovery financing ever. With Nobel Prize-winning science, $3 billion in pharma deals, and zero approved drugs, the company is making the biggest bet the field has ever seen.