At the ASCO 2026 annual meeting, a comprehensive clinical update from the alliance between Merck & Co. and Kelun-Biotech has introduced a potential paradigm shift in the first-line management of advanced non-small cell lung cancer (NSCLC). Data derived from an interim analysis of the China-based Phase 3 OptiTROP-Lung05 study revealed that combining sacituzumab tirumotecan (sac-TMT) — a TROP2-directed antibody-drug conjugate (ADC) — with the immune checkpoint inhibitor Keytruda reduced the risk of disease progression or mortality by 65% compared to Keytruda monotherapy in treatment-naïve, PD-L1-positive NSCLC cohorts.
The primary clinical performance indicators validated from the study outline the following metrics:
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Progression-Free Survival (PFS): Following a median follow-up duration of 10.5 months, the median PFS threshold for the combination arm was not yet reached, whereas the control cohort receiving Keytruda alone exhibited a median PFS of 5.7 months. The final definitive PFS evaluation is scheduled for completion in the second half of 2026.
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Overall Response Rate (ORR): The integrated sac-TMT and Keytruda regimen achieved a trial-wide objective response rate of 70.2%, substantially outperforming the 42% baseline recorded in the monotherapy arm.
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Overall Survival (OS) Trends: While the overall survival metrics remained immature at the definitive September 2025 data cutoff window, preliminary calculations demonstrated a robust 45% survival improvement trend favoring the combination strategy.
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Tolerability and Safety Profile: Grade 3 or higher treatment-emergent adverse events (TEAEs) were documented at 55.3% within the combination cohort versus 31.4% in the monotherapy control group. Crucially, toxicities leading to the total discontinuation of the sac-TMT molecule were limited to 3.8% of treated subjects.
This robust clinical readout positions the Merck-Kelun therapeutic regimen at the forefront of a commercial showdown with alternative innovative biological modalities, notably the emerging class of PD-(L)1xVEGF bispecific antibodies, such as Akeso and Summit Therapeutics’ ivonescimab, which demonstrated a 49% PFS benefit in the parallel Harmoni-2 protocol. Industry analysts note that sac-TMT’s treatment efficacy appears remarkably consistent across diverse patient subgroups regardless of historical squamous or nonsquamous histology and varying PD-L1 expression baselines. Based on these outcomes, regulatory authorities in China are currently reviewing Kelun’s market authorization application, while Merck & Co. continues to expand its global development footprint by spearheading 17 international Phase 3 clinical protocols evaluating sac-TMT across multiple oncological indications.