• As a head-to-head Phase III trial comparing sac-TMT plus pembrolizumab with the first-line standard of care (immunotherapy plus chemotherapy), OptiTROP-Lung06 demonstrated the superiority of replacing conventional pemetrexed/platinum chemotherapy with sac-TMT, with significantly prolonged PFS and a positive OS trend compared with pembrolizumab plus pemetrexed and platinum-based chemotherapy.
• Focusing on the particularly challenging first-line treatment for PD-L1-negative non-squamous NSCLC population, the introduction of a TROP2 ADC to a PD-1 mAb not only delivers ADC's precise targeting and killing of tumor cells, but also activates the immune microenvironment through their synergetic mechanisms. This strategy is expected to unlock the therapeutic potential of the PD-1 mAb in patients with PD-L1-negative or limited immune responses, breaking this therapeutic bottleneck.
• Following the meeting of the primary endpoint in the Phase III OptiTROP-Lung05 study for first-line PD-L1-positive NSCLC, the positive results were achieved in another Phase III trial of sac-TMT plus pembrolizumab, providing robust clinical evidence supporting the expansion of this combination regimen to a broader first-line NSCLC population.

CHENGDU, China, July 15, 2026 /PRNewswire/ -- Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. ("Kelun-Biotech" or the "Company", 6990.HK) announced today that the Independent Data Monitoring Committee (IDMC) concluded that the Phase III clinical study (OptiTROP-Lung06) of its trophoblast cell-surface antigen 2 (TROP2)-directed antibody drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870) (佳泰莱^®), in combination with MSD's^[1] anti-programmed cell death protein 1 (PD-1) therapy KEYTRUDA^®[2] (pembrolizumab) as a first-line treatment for programmed death-ligand 1 (PD-L1)-negative locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) has met its primary endpoint of progression‑free survival (PFS) at a prespecified interim analysis. This is the world's first Phase III clinical study of an ADC combined with an immune checkpoint inhibitor to meet its primary endpoint in the first-line treatment of driver gene‑negative and PD‑L1‑negative non-squamous NSCLC.

OptiTROP-Lung06 is a randomized, open‑label, multicenter Phase III clinical study evaluating the efficacy and safety of sac-TMT in combination with pembrolizumab versus chemotherapy in combination with pembrolizumab as first-line treatment for patients with locally advanced or metastatic non-squamous NSCLC who have PD-L1 tumor proportion score (TPS) <1%. The primary endpoint of the study was PFS assessed by blinded independent central review (BICR); secondary endpoints included overall survival (OS), safety and others. At a pre-specified interim analysis, the sac-TMT combined with pembrolizumab demonstrated a statistically significant and clinically meaningful improvement in PFS compared with pembrolizumab combined with pemetrexed and platinum-based chemotherapy, and a positive trend in OS was also observed. The safety profile of sac-TMT combined with pembrolizumab was consistent with that observed in previously reported studies, and no new safety signals were observed. The Company plans to communicate with the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) of China based on the results of this sac‑TMT study.

Previously, the Phase III registrational OptiTROP-Lung05 study of sac-TMT in combination with pembrolizumab as first-line treatment for PD-L1-positive NSCLC had successfully met its primary endpoint, supporting the submission of a new indication application to the CDE. The findings of the OptiTROP-Lung05 study were presented as an oral report at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and simultaneously published in The Lancet. The positive results from the OptiTROP-Lung06 study mark the further expansion of sac-TMT plus immunotherapy into the PD-L1-negative population in first-line non-squamous NSCLC, providing clinical support for this combination strategy to cover a broader first-line NSCLC population and are expected to drive the optimization of first-line treatment landscape for driver gene-negative non-squamous NSCLC.

Professor Caicun Zhou, National Lead Principal Investigator from Shanghai East Hospital, Tongji University, said: "For patients with driver gene‑negative and PD‑L1‑negative NSCLC, immunotherapy combined with chemotherapy remains the current standard first-line treatment and has improved patient outcomes to some extent. However, long-term survival benefit remains limited. The achievement of positive results in the Phase III OptiTROP-Lung06 study represents an important breakthrough in the first-line treatment of PD-L1-negative NSCLC. These results not only provide robust clinical evidence supporting the 'ADC plus immunotherapy' strategy of sac-TMT in combination with pembrolizumab, but also have the potential to offer these patients a new first-line treatment option beyond the current standard of care, with the promise of improved survival outcomes."

Dr. Michael GE, CEO of Kelun-Biotech, stated: "We are delighted to see that sac-TMT combined with pembrolizumab has achieved exciting positive results compared with immunotherapy plus chemotherapy in the first-line treatment of patients with PD-L1-negative NSCLC. This ADC plus immunotherapy regimen has previously demonstrated superior efficacy over immunotherapy monotherapy in patients with PD-L1-positive NSCLC. The positive results of both the OptiTROP-Lung05 and OptiTROP-Lung06 studies confirm the strong synergetic effect of sac-TMT combined with pembrolizumab, supporting the potential of this combination regimen to benefit the broad first-line NSCLC population and bringing new treatment opportunities to patients with different PD-L1 expression levels."

Sac-TMT is currently being evaluated in ten registrational studies in lung cancer, including five registrational studies in China and five global multicenter Phase III studies.

About sac-TMT(佳泰莱^®)
Sac-TMT, a core product of the Company, is a novel human TROP2 ADC in which the Company has proprietary intellectual property rights, targeting advanced solid tumors such as NSCLC, breast cancer (BC), gastric cancer (GC), gynecological tumors and genitourinary tumors, among others. Sac-TMT is developed with a unique, bifunctional linker that maximizes payload delivery to tumor cells both through its irreversible connection with the anti-TROP2 monoclonal antibody sacituzumab and its pH-sensitive cleavage from a belotecan-derivative topoisomerase I inhibitor payload in the lysosome, with a drug-to-antibody-ratio (DAR) of 7.4. Sac-TMT specifically recognizes TROP2 on the surface of tumor cells by recombinant anti-TROP2 humanized monoclonal antibodies, which is then endocytosed by tumor cells and releases the payload KL610023 intracellularly. KL610023, as a topoisomerase I inhibitor, induces DNA damage to tumor cells, which in turn leads to cell-cycle arrest and apoptosis. In addition, it also releases KL610023 in the tumor microenvironment. Given that KL610023 is membrane permeable, it can enable a bystander effect, or in other words kill adjacent tumor cells.

In May 2022, the Company licensed the exclusive rights to MSD (the tradename of Merck & Co., Inc, Rahway, NJ, USA) to develop, use, manufacture and commercialize sac-TMT in all territories outside of Greater China (which includes Mainland China, Hong Kong, Macao and Taiwan).

To date, four indications for sac-TMT have been approved and marketed in China for: 1) unresectable locally advanced or metastatic triple‑negative breast cancer (TNBC) who have received at least two prior systemic therapies (at least one of them for advanced or metastatic setting); 2) EGFR mutant-positive locally advanced or metastatic non-squamous NSCLC following progression on epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapy and platinum-based chemotherapy; 3) epidermal growth factor receptor (EGFR) mutant-positive locally advanced or metastatic non-squamous NSCLC who progressed after treatment with EGFR-TKI therapy; 4) unresectable or metastatic hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) (Immunohistochemistry (IHC) 0, IHC 1+ or IHC 2+/In Situ Hybridization (ISH)-) BC who have received prior endocrine therapy and at least one line of chemotherapy in advanced setting. The first two indications above have been included in China's National Reimbursement Drug List (NRDL). This inclusion is expected to bring clinically meaningful benefits to a greater number of patients with BC and NSCLC. Additionally, sac-TMT has been granted six Breakthrough Therapy Designations (BTDs) by the NMPA.

Sac-TMT is the world's first TROP2 ADC drug approved for marketing in lung cancer. A new indication application for sac-TMT in combination with pembrolizumab (KEYTRUDA^®) as first‑line treatment for locally advanced or metastatic NSCLC who have PD-L1 TPS≥1% and are EGFR-negative and anaplastic lymphoma kinase (ALK)-negative has been accepted for review by the NMPA, and has entered the priority review and approval process. As of today, Kelun-Biotech has initiated 9 registrational clinical studies in China. MSD has initiated 17 ongoing global Phase III clinical studies of sac-TMT as a monotherapy or in combination with pembrolizumab or other anti-cancer agents for several types of cancer. These studies are sponsored and led by MSD.

About Kelun-Biotech
Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical, which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. Kelun-Biotech focuses on major disease areas such as solid tumors, autoimmune, and metabolic diseases, and in establishing a globalized drug development and industrialization platform to address the unmet medical needs in China and the rest of world. Kelun-Biotech is committed to becoming a leading global enterprise in the field of innovative drugs. At present, Kelun-Biotech has more than 30 ongoing key innovative drug projects, of which 4 projects with 8 indications have been approved for marketing, 1 project is in the NDA stage and more than 10 projects are in the clinical stage. Kelun-Biotech has established one of the world's leading proprietary ADC and novel DC platforms, OptiDC™, and has 2 ADC projects with 5 indications approved for marketing, and multiple ADC and novel DC assets in clinical or preclinical research stage. For more information, please visit https://en.kelun-biotech.com/.