Kelun and MSD's sac-TMT halves progression risk in PD-L1-negative lung cancer in Phase 3

Kelun-Biotech presented the Phase 3 OptiTROP-Lung06 trial of sacituzumab tirumotecan (sac-TMT), its TROP2-directed antibody-drug conjugate licensed outside Greater China to MSD, as a late-breaking oral presentation (LBA66) at the ESMO Congress in Madrid on 25 October 2026, with simultaneous publication in the New England Journal of Medicine ¹³. Combined with MSD's Keytruda (pembrolizumab), sac-TMT cut the risk of disease progression or death by 51% against platinum doublet chemotherapy plus Keytruda in first-line PD-L1-negative non-squamous non-small cell lung cancer (NSCLC) ¹.

What the trial found

The open-label, multicentre study randomised 455 patients 1:1 whose tumours had a PD-L1 tumour proportion score below 1% and no EGFR mutation or ALK alteration ¹. The comparator arm received pemetrexed with cisplatin or carboplatin plus pembrolizumab ¹. At the data cut-off of 9 June 2026, median follow-up was 9.7 months ¹.

• Progression-free survival by blinded independent central review: hazard ratio 0.49 (95% CI 0.36-0.65; P<0.0001), median 15.0 months against 5.7 months ¹.

• Overall survival at this interim look: hazard ratio 0.58 (95% CI 0.38-0.88), with the median not reached in either arm ¹.

• Objective response rate: 50.2% against 47.3%; deep responses, defined as a response with at least a 50% shrinkage in target lesions, 28.8% against 17.3% ¹.

• Median duration of response: 13.6 months against 6.8 months (HR 0.47) ¹.

On safety, the company reported fewer grade 3 or worse treatment-emergent adverse events and fewer dose cuts or discontinuations in the sac-TMT arm, a similar rate of interstitial lung disease or pneumonitis in both arms, and no new safety signals ¹. Kelun describes the study as the first Phase 3 trial of an ADC paired with a checkpoint inhibitor to meet its primary endpoint in this driver-negative, PD-L1-negative population ¹.

Giannis Mountzios of Henry Dunant Hospital Centre in Athens, the ESMO discussant, said the PFS data "have the potential to be immediately practice-changing in patients with PD-L1-negative tumours who experience poor outcomes" ³.

What it means for the market

The result targets the part of first-line NSCLC where Keytruda plus chemotherapy works least well, and gives sac-TMT a case for displacing platinum chemotherapy as the partner drug in those patients ³. Read with the OptiTROP-Lung05 data shown at ASCO 2026, Kelun's investigator argues the combination has now shown a PFS benefit in NSCLC without actionable alterations whatever the PD-L1 level ¹.

For MSD, which licensed the asset in May 2022 in a deal valued at up to $1.4 billion, the immediate effect is on trial strategy rather than on Western labels ¹³. MSD runs 18 global Phase 3 studies of sac-TMT, and its first-line lung effort centres on TroFuse-007 in high PD-L1 expressers, which is due to read out in 2028 ¹³. The new data could push MSD towards an ex-China trial in the PD-L1-negative group ³. When the topline result was announced in July, a Leerink Partners analyst wrote that the China-only design meant no immediate global impact for Merck, while calling it a proof-of-concept for the drug ².

In China the drug already holds four approved indications, two of them on the National Reimbursement Drug List, and two further first-line applications, including sac-TMT plus pembrolizumab in PD-L1 TPS of 1% or more NSCLC, are under priority review at the NMPA ¹.

Caveats

All 455 patients were enrolled in China, the trial was open-label, and the figures come from an interim analysis after a median 9.7 months of follow-up ¹³. Overall survival is immature, with medians not reached ¹. MSD's TroFuse-007 readout in 2028 remains the next major test of the regimen in first-line NSCLC outside China ³.