Kelun-Biotech Announces Phase III Study of Sacituzumab Tirumotecan (sac-TMT) in Combination with Pembrolizumab as First-Line Treatment for PD-L1-Negative Non-Squamous NSCLC Met Primary Endpoint

Kelun-Biotech said its Phase III OptiTROP-Lung06 trial met the primary PFS endpoint at a prespecified interim analysis for sacituzumab tirumotecan (sac-TMT) plus pembrolizumab in first-line PD-L1-negative (PD-L1 TPS <1%) non-squamous NSCLC, showing a statistically significant, clinically meaningful PFS improvement versus pembrolizumab plus pemetrexed/platinum and a positive OS trend. Management noted no new safety signals versus prior studies. The company plans to engage China’s CDE (NMPA) based on the OptiTROP-Lung06 results, building on OptiTROP-Lung05’s earlier positive Phase III readout in PD-L1-positive disease.

Analysis

This is more relevant to Merck’s franchise durability than to near-term revenue. The market should treat the readout as an extension-of-lifespan signal for Keytruda: if an ADC backbone can displace chemo in first-line NSCLC, Merck can keep the regimen relevant deeper into the post-patent window while shifting mix toward higher-value biologic combinations. The immediate P&L impact is modest, but the implied strategic benefit is that Keytruda becomes harder to dislodge in the largest lung cancer settings.

Second-order, the biggest pressure is not on Merck but on IO-chemo incumbents and ADC rivals. If physicians adopt ADC+PD-1 as a preferred backbone, the loser is conventional platinum/pemetrexed usage and, over time, any rival regimen that depends on chemo as the default platform. This also raises the bar for competing TROP2 programs: investors will now demand not just response-rate data, but proof that combination sequencing can win in biomarker-low disease without toxicity tradeoffs.

The contrarian issue is geography and timing. A China Phase III win is not the same as a U.S./EU commercial catalyst, and the valuation gap between headline validation and actual global label expansion can stay wide for 6-18 months. The key falsifier is a weaker OS translation or any emerging safety drag once the full dataset matures; if that happens, the market will likely reclassify this as a China-only asset and strip away much of the option value.

Key Decisions for Investors

• Add MRK on any post-news weakness rather than chasing the first move; view this as a 6-18 month Keytruda life-cycle extension story, not a same-day earnings event.
• Pair trade: long MRK / short BMY into the next 1-3 months of oncology catalysts. If ADC+PD-1 becomes the preferred first-line framework, BMY’s NSCLC positioning is more exposed to regimen substitution while MRK benefits from backbone stickiness.
• Buy a limited-risk MRK upside structure on pullbacks, e.g. Jan-2027 call spreads, only if you believe global confirmation is likely; the risk/reward is attractive because the downside is defined and the upside is tied to label-expansion optionality.
• Treat the China biotech readthrough as a watch item for 6990.HK and broader ADC baskets, not a standalone buy here; wait for OS maturity, NMPA timing, and any ex-China data before assigning durable valuation uplift.