The first ADC-immunotherapy combo to clear this hurdle in first-line lung cancer
In the long human struggle against lung cancer — a disease that claims hundreds of thousands of lives each year — a Chinese biotech has reached a meaningful threshold. Sichuan Kelun-Biotech announced that its antibody-drug conjugate sac-TMT, combined with Merck's immunotherapy Keytruda, outperformed Keytruda alone in slowing disease progression among patients with advanced non-small cell lung cancer carrying the PD-L1 marker. It is the first time a drug of this class has cleared a late-stage trial in this setting, opening a potential new path for patients who have long needed more options at the moment of first diagnosis.
- Advanced lung cancer remains one of the world's deadliest diagnoses, and the search for effective first-line treatments carries enormous urgency for patients with few alternatives.
- The Phase III OptiTROP-Lung05 trial broke new ground — no antibody-drug conjugate had ever before hit its primary endpoint in combination with an immune checkpoint inhibitor for newly diagnosed advanced lung cancer.
- The combination of sac-TMT and Keytruda delivered a statistically significant improvement in progression-free survival, with early signals also pointing toward better overall survival, though final data are still pending.
- Kelun-Biotech is now moving to file a supplemental drug application with Chinese regulators, while partner Merck runs fifteen global Phase III studies testing sac-TMT across multiple cancer types.
- The drug's unique bystander effect — its ability to kill tumor cells the antibody never directly reached — may help explain its potency and positions sac-TMT as a potential platform therapy across a wide range of solid tumors.
Sichuan Kelun-Biotech announced Monday that its experimental drug sac-TMT, paired with Merck's immunotherapy Keytruda, succeeded in slowing cancer progression better than Keytruda alone in patients with advanced non-small cell lung cancer whose tumors expressed the PD-L1 protein marker. The result marks the first time an antibody-drug conjugate has hit its primary endpoint in a late-stage trial when combined with an immune checkpoint inhibitor for newly diagnosed advanced lung cancer — a distinction that sets this finding apart in a crowded field.
The Phase III trial, OptiTROP-Lung05, enrolled patients with locally advanced or metastatic disease and randomly assigned them to receive either the combination or Keytruda by itself. An independent monitoring committee found the combination produced a statistically significant and clinically meaningful improvement in progression-free survival. A positive trend in overall survival was also observed, though those numbers remain preliminary.
Sac-TMT belongs to a class of drugs engineered to deliver toxic payloads directly to cancer cells. It targets TROP2, a protein common on tumor surfaces, and once bound, releases a DNA-damaging agent inside the cell. Notably, the payload can also penetrate neighboring cells — a bystander effect that amplifies its reach beyond direct contact.
The drug already holds approval in China for triple-negative breast cancer and EGFR-resistant lung cancer, with results published in The New England Journal of Medicine and The BMJ. Kelun-Biotech licensed global rights outside Greater China to Merck in 2022, and the two companies are now running a combined twenty-four registrational studies worldwide across lung, breast, gastric, and gynecological cancers.
Following the interim results, Kelun-Biotech plans to seek a supplemental drug approval in China for the first-line PD-L1-positive lung cancer setting. For patients facing one of the world's most lethal diseases, a proven new option at the moment of first treatment could meaningfully shift the course of care.
A Chinese biotech company announced on Monday that it has cleared a significant hurdle in the race to treat advanced lung cancer. Sichuan Kelun-Biotech's experimental drug sac-TMT, when paired with Merck's established immunotherapy Keytruda, showed it could slow disease progression better than Keytruda alone in patients whose tumors carried a specific marker called PD-L1. The finding matters because it represents the first time a drug from the antibody-drug conjugate class—a relatively newer category of cancer medicines—has succeeded in a late-stage trial when combined with an immune checkpoint inhibitor for newly diagnosed advanced lung cancer.
The trial, called OptiTROP-Lung05, enrolled patients with locally advanced or metastatic non-small cell lung cancer, the most common form of the disease. Researchers randomly assigned them to receive either the sac-TMT and Keytruda combination or Keytruda by itself. At an interim analysis, the independent monitoring committee overseeing the study found that the combination therapy delivered what the company describes as a statistically significant and clinically meaningful improvement in progression-free survival—the length of time before the cancer worsened. Researchers also observed a positive trend in overall survival, though final data on that measure were not yet available.
Sac-TMT works through a mechanism distinct from traditional chemotherapy. The drug is an antibody engineered to recognize and bind to TROP2, a protein found on the surface of many cancer cells. Once attached, the antibody delivers a payload—a topoisomerase I inhibitor derived from belotecan—directly into the tumor cell, where it damages DNA and triggers cell death. The drug carries an average of 7.4 payload molecules per antibody. Because the payload is membrane-permeable, it can also kill neighboring tumor cells that the antibody never directly contacted, a phenomenon researchers call the bystander effect.
Kelun-Biotech has already won approval in China for sac-TMT in other settings. The drug is marketed there for triple-negative breast cancer in heavily pretreated patients and for EGFR-mutant lung cancer that has progressed despite prior targeted therapy. In those earlier trials, sac-TMT demonstrated improvements in both progression-free and overall survival compared to standard chemotherapy, making it the first antibody-drug conjugate to show such dual benefits in the EGFR-resistant population. Those results were published in The New England Journal of Medicine and The BMJ.
The company licensed global rights outside Greater China to Merck in May 2022, a partnership that has since expanded significantly. Merck is now running fifteen Phase III studies of sac-TMT worldwide, testing it as a monotherapy and in combination with Keytruda and other cancer drugs across multiple tumor types. Kelun-Biotech itself is conducting nine registrational studies in China. The OptiTROP-Lung05 result is one of five global Phase III trials the company is running and one of five such trials in China.
Based on the interim findings, Kelun-Biotech said it plans to approach China's Center for Drug Evaluation to discuss filing a supplemental new drug application for sac-TMT in the first-line PD-L1-positive lung cancer setting. The company is also pursuing approval for sac-TMT in hormone receptor-positive, HER2-negative breast cancer in patients who have received prior endocrine therapy, a supplemental application that has already been accepted and placed on a priority review track. The breadth of the pipeline—ten registrational lung cancer studies alone, plus trials in breast, gastric, and gynecological cancers—suggests the company sees sac-TMT as a potential platform therapy across multiple solid tumors. For patients with advanced lung cancer, a disease that kills hundreds of thousands annually worldwide, the addition of another effective first-line option could reshape treatment decisions in the coming years.
Citações Notáveis
Demonstrated a statistically significant and clinically meaningful improvement in progression-free survival, with a positive trend in overall survival also observed— Kelun-Biotech announcement regarding OptiTROP-Lung05 interim analysis
A Conversa do Hearth Outra perspectiva sobre a história
What exactly is an antibody-drug conjugate, and why does it matter that this one worked with an immunotherapy?
Think of it as a guided missile. The antibody finds cancer cells marked with a specific protein, then delivers a toxic payload directly inside. The innovation here is pairing it with Keytruda, which wakes up the immune system. Separately, each has limits. Together, they seem to work better.
The trial showed improvement in progression-free survival. What about whether people actually lived longer?
That's the honest answer—they saw a positive trend in overall survival, but the data aren't final yet. Progression-free survival is what they measured first. Overall survival takes longer to accumulate because you have to wait for events. It's coming.
This drug is already approved in China for other lung cancers. Why is this first-line result different?
The earlier approvals were for patients whose tumors had specific mutations and who'd already failed other drugs. This is earlier in the disease course, for a broader population defined by a different marker. It's a bigger market, and it's a harder population to treat because you haven't narrowed it down yet.
How many patients were in this trial?
The announcement doesn't specify the enrollment number. They released the primary endpoint result but held back granular details. That will come when they publish the full data.
What's the timeline for getting this approved?
They're going to talk to Chinese regulators now about a supplemental application. In China, that process can move relatively quickly, especially for drugs addressing serious unmet needs. But there's no announced date yet.
Is this drug available outside China?
Not yet in any approved indication. Merck licensed the rights outside Greater China and is running the global trials. If those succeed, it could eventually reach patients in the U.S., Europe, and elsewhere. But that's still ahead.
Why does it matter that this is the first ADC-immunotherapy combo to hit this endpoint?
Because it proves the concept works. There's been a lot of theoretical reason to think combining these approaches would help, but until you run the trial and it succeeds, you don't know. Now others will likely pursue similar combinations. It opens a door.