Sac-TMT Adds 8.5 Months of Survival After EGFR Therapy

Kelun-Biotech's sacituzumab tirumotecan delivered a mature survival result in a second lung cancer setting. In the Phase 3 OptiTROP-Lung04 trial, patients with EGFR-mutant nonsquamous non-small cell lung cancer lived a median 25.9 months on sac-TMT, compared with 17.4 months on platinum-based chemotherapy after their disease had progressed on EGFR-targeted therapy.

The hazard ratio for death was 0.69, with a 95% confidence interval of 0.54 to 0.89 and a one-sided P value of 0.0021. That represents a 31% estimated reduction in the risk of death. At two years, 54.1% of patients in the sac-TMT group were alive, compared with 37.2% in the chemotherapy group.

The study randomized 376 patients and had a median follow-up of 32.3 months at the final survival analysis. Earlier data had already shown a progression-free survival hazard ratio of 0.49, meaning the risk of progression or death was about half that of chemotherapy. China approved sac-TMT for this EGFR-mutant setting in September 2025, so the final survival analysis strengthens the evidence behind an existing indication rather than marking a first approval.

Subsequent treatment complicates the comparison but does not erase it. About 22.6% of patients assigned to chemotherapy later received another antibody-drug conjugate. A prespecified rank-preserving structural failure time model, which attempts to adjust for that treatment crossover, estimated median survival of 25.9 months versus 16.6 months and a hazard ratio of 0.57. That adjusted analysis is supportive, but the unadjusted randomized result remains the primary evidence because model-based corrections depend on assumptions.

No new safety signal appeared with longer follow-up. The most common treatment-related events were blood-related toxicities and stomatitis. Grade 3 stomatitis occurred in 4.8% of sac-TMT patients. Interstitial lung disease or pneumonitis was reported in one patient, or 0.5%, in the sac-TMT group and two patients, or 1.1%, in the chemotherapy group; all cases were grade 1 or 2.

The result has different commercial implications by territory. Kelun-Biotech, traded as 6990.HK, retains rights to sac-TMT in Greater China. Merck holds exclusive rights outside Greater China and lists the drug as MK-2870 in its oncology pipeline. The China approval demonstrates that the program can reach the market, while the mature survival benefit gives Merck a stronger clinical rationale for development elsewhere.

The key investor distinction is that OptiTROP-Lung04 now offers final overall-survival evidence, not just tumor-response or progression data. Regulatory paths outside China may still require territory-specific trials and reviews, but an 8.5-month median survival advantage provides a substantial benchmark for the program.