Kelun-Biotech's sac-TMT cuts lung cancer risk by 65% in Phase III

Kelun-Biotech's TROP2 ADC sac-TMT reduced the risk of disease progression or death by 65% versus pembrolizumab alone in first-line PD-L1-positive non-small cell lung cancer, data from the Phase III OptiTROP-Lung05 trial show.

Sac-TMT plus pembrolizumab cut the risk of disease progression or death by 65% compared with pembrolizumab alone in 413 patients with PD-L1 TPS of 1% or higher advanced non-small cell lung cancer, according to results presented at the 2026 ASCO Annual Meeting and published simultaneously in The Lancet.

"The positive results of the OptiTROP-Lung05 study are encouraging and support the application of sac-TMT in an earlier-line setting for lung cancer," Professor Caicun Zhou, the national leading principal investigator from Shanghai East Hospital, Tongji University, said in a statement.

Median progression-free survival was not reached in the combination arm versus 5.7 months for pembrolizumab alone, with a hazard ratio of 0.35. The 12-month PFS rate reached 62.4% compared with 29%. Objective response rate was 70.2% versus 42%, and the deep response rate — defined as tumor shrinkage of at least 60% — was 49% versus 25.9%. Overall survival data were not yet mature but showed a positive trend, with a 12-month OS rate of 80.4% versus 68.9% and a hazard ratio of 0.55.

The results position sac-TMT as the first TROP2 ADC to show a survival benefit in first-line NSCLC, a market with more than 2 million new cases annually worldwide. Kelun-Biotech has already submitted a new indication application to China's NMPA for the combination regimen, which has entered priority review. The company's partner MSD is evaluating sac-TMT across 17 global Phase III trials.

How sac-TMT works and where it stands

Sac-TMT is a novel antibody-drug conjugate that uses a bifunctional linker to connect a belotecan-derivative topoisomerase I inhibitor payload to an anti-TROP2 monoclonal antibody, achieving a drug-to-antibody ratio of 7.4. The linker is pH-sensitive, releasing the payload inside tumor cells and enabling a bystander effect against adjacent cancer cells. This mechanism differentiates it from other TROP2 ADCs such as Gilead's Trodelvy, which uses a different linker-payload chemistry.

The benefit was consistent across all prespecified subgroups. In patients with PD-L1 TPS of 50% or higher, the PFS hazard ratio was 0.47, while in those with TPS of 1% to 49%, it was 0.28. Among patients with non-squamous histology, the HR was 0.28, and for squamous disease, it was 0.44. Safety data showed a higher incidence of grade 3 or higher treatment-emergent adverse events in the combination arm, driven primarily by expected hematologic toxicities of sac-TMT. No sac-TMT-related deaths occurred, and no new safety signals were identified.

Analyst reaction and what comes next

Goldman Sachs raised its price target on Kelun-Biotech to HKD561.4 from HKD526.49, maintaining a Buy rating. The bank said the data are solid enough to support regulatory approval and provide strong reference support for the global Phase III TroFuse-07 trial. Goldman Sachs raised its 2027 and 2028 EPS estimates to RMB7.49 and RMB14.32, respectively.

Kelun-Biotech already has four approved indications in China, two of which are included in the National Reimbursement Drug List, and six Breakthrough Therapy Designations from the NMPA. With MSD shouldering global development costs under the 2022 licensing deal, Kelun-Biotech's cash runway is supported by milestone payments and China commercial revenue. The NMPA priority review decision on the first-line NSCLC indication is the next major catalyst for the stock, which trades on the Hong Kong Stock Exchange under ticker 6990.

This article is for informational purposes only and does not constitute investment advice.