Kelun-Biotech's sac-TMT success is a landmark proof-of-concept, but its value remains speculative due to critically immature overall survival (OS) data and a complete absence of safety figures. The combination with Keytruda successfully replaced platinum chemotherapy in a Phase 3 first-line trial for PD-L1-negative non-squamous NSCLC, meeting its primary progression-free survival (PFS) endpoint. While a "positive OS trend" was reported, this qualitative statement falls short of the high bar set by other ADC-IO combinations like enfortumab vedotin, which demonstrated a definitive OS benefit (HR 0.47) in its pivotal EV-302 trial. [1] The positive precedent for sac-TMT is the approval of T-DM1, which was initially based on PFS and interim OS data from the EMILIA study, suggesting a potential accelerated approval pathway. However, the cautionary tale of datopotamab deruxtecan, which showed a PFS benefit but failed on OS in breast cancer, underscores the risk of relying on early trends. [2] Without hazard ratios, response rates, or Grade ≥3 adverse event data, especially regarding the known ADC class risk of ILD/pneumonitis, the asset’s profile is unverifiable. The entire proposition hinges on the OS trend maturing into a statistically significant and clinically meaningful benefit that can justify its likely premium cost to payers.
The trial met its PFS primary endpoint, but the OS benefit is only a "positive trend" and no specific efficacy or safety data (hazard ratios, AE rates) were disclosed, making the asset's true profile impossible to assess.
| Indication | non-small cell lung cancer |
| Drug | sacituzumab tirumotecan |
| Mechanism of Action | TROP2 ADC, PD-1 inhibitor |
| Company | Kelun-Biotech |
| Trial Phase | Phase 3 |
| Category | Clinical Trial Event |
| Sub Category | Topline Results Positive |
| Therapeutic Area | Oncology |
| Combination Partner | Keytruda (pembrolizumab) |
| Primary Endpoint | Progression-free survival (PFS) |
| Secondary Endpoint | Overall survival (OS) |
| Patient Population | PD-L1-negative non-squamous NSCLC |
| Line of Therapy | First-line |
| Comparator | Keytruda/chemotherapy combo |
| Deal Value | $1.4 billion |
| Regulatory Agency | China's chief drug regulator |
| Licensing Agreement Date | December 2022 |
| Conference Name | European Society for Medical Oncology |
Kelun's Sac-TMT + Keytruda Succeeds in Phase 3 NSCLC Trial
Kelun-Biotech's sacituzumab tirumotecan (sac-TMT), partnered with Merck, achieved success in a Phase 3 non-small cell lung cancer (NSCLC) trial. The antibody-drug conjugate (ADC), when combined with Merck's Keytruda and chemotherapy, met its primary endpoint of progression-free survival (PFS) and showed a positive trend in overall survival (OS). This marks the first direct proof-of-concept for an ADC replacing platinum-based chemotherapy in a first-line NSCLC regimen, particularly for the challenging PD-L1-negative non-squamous patient population. This follows sac-TMT's earlier Phase 3 win in endometrial cancer, further validating the Merck-Kelun partnership.
- The Phase 3 trial demonstrated that sac-TMT, in combination with Keytruda and chemotherapy, significantly improved progression-free survival (PFS) and showed a positive trend in overall survival (OS) in non-small cell lung cancer. This success is particularly notable for the difficult-to-treat PD-L1-negative non-squamous NSCLC population, where it offers a new first-line treatment option.
- The trial provides the first direct proof-of-concept for an antibody-drug conjugate (ADC) replacing platinum-based chemotherapy in a first-line NSCLC standard-of-care regimen. The combination of a TROP2 ADC like sac-TMT with a PD-1 monoclonal antibody (Keytruda) leverages synergistic mechanisms to precisely target tumor cells and activate the immune microenvironment, potentially overcoming therapeutic bottlenecks in PD-L1-negative patients.
- This latest Phase 3 win builds on the strong clinical momentum for sac-TMT, following its success in a Phase 3 endometrial cancer trial in May. It further validates the $1.4 billion licensing agreement between Merck and Kelun-Biotech from December 2022, which aimed to augment Merck's oncology pipeline with advanced ADC technologies. Kelun plans to discuss these results with China's drug regulator, with future global data expected.
Unlocking Potential: Sac-TMT for Challenging PD-L1-Negative NSCLC
Despite significant advancements in targeted and immune-based therapies, non-small cell lung cancer (NSCLC) continues to present formidable clinical challenges, particularly in advanced or metastatic settings. The limitations of current treatment paradigms are multifaceted, spanning from the inherent biological complexity of the disease to issues with drug efficacy and resistance, which collectively contribute to poor long-term survival outcomes.
Pervasive Drug Resistance and Poor Survival: Therapeutic resistance is a near-universal eventuality in advanced NSCLC, limiting the long-term benefit of all treatment modalities, including chemotherapy, targeted agents, and immunotherapies. Consequently, metastatic disease remains lethal, with a median survival time of only 8-12 months, and a cure is not yet achievable.
Limited Efficacy of Targeted and Immune Therapies: While transformative for some, the applicability of targeted agents is restricted, as actionable driver mutations (e.g., EGFR, ALK) are present in only about 20% of Western NSCLC patients. Furthermore, most patients either do not respond to immune checkpoint inhibitors (ICIs) or develop acquired resistance, even in PD-L1-positive tumors, highlighting the need to overcome these survival mechanisms.
Plateaued Effectiveness of Conventional Modalities: Conventional chemotherapy, a long-standing backbone of treatment, has reached a plateau in its efficacy for NSCLC. Newer modalities like antibody-drug conjugates (ADCs), while promising, also face hurdles, including the development of treatment resistance and notable toxicities that can complicate patient management.
Challenges in Diagnosis and Treatment Access: The majority of patients are diagnosed at an advanced stage when the disease has already metastasized, precluding the optimal window for surgical intervention. Compounding this, a striking proportion of patients with metastatic disease—nearly half (46.8%) in one large study—never receive any systemic therapy, indicating significant gaps in access to care or clinical inertia.
Molecular Heterogeneity and the Biomarker Imperative: NSCLC is a highly complex and molecularly heterogeneous disease. This means that any specific treatment is likely to benefit only a subset of patients, making the discovery and validation of predictive biomarkers imperative for rationally selecting patients who are most likely to respond to a given therapy.
Merck-Kelun's Sac-TMT: A Growing Pipeline Beyond NSCLC
Beyond its development in non-small cell lung cancer, sacituzumab tirumotecan (sac-TMT) is also being evaluated in other advanced solid tumors, with a significant focus on breast cancer. The Phase 1/2 MK-2870-001 (KL264-01) study (NCT04152499) has provided key data on its manageable safety profile and promising antitumor activity in these indications.
The primary indications being investigated outside of NSCLC are metastatic triple-negative breast cancer (TNBC) and hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer.
The trial's intervention model began with Phase 1 dose-escalation cohorts for patients with various unresectable, locally advanced, or metastatic solid tumors refractory to standard therapies. This was followed by Phase 2 dose-expansion cohorts focusing specifically on the TNBC and HR+/HER2- breast cancer populations.
In the Phase 2 expansion for metastatic TNBC, the objective response rate (ORR) was 34.8% for the 4-mg/kg group (n=23) and 38.9% for the 5-mg/kg group (n=36).
The HR+/HER2- breast cancer cohort (n=41) showed an ORR of 31.7%.
Following these positive signals in unresectable locally advanced or metastatic breast cancer, sac-TMT is now advancing into Phase 3 clinical development.
Frequently Asked Questions
References
- [1] Prasse A, Waller C et al.. [Lung cancer from the perspective of internal medicine and surgery]. Der Radiologe. 2010 Aug. 20652215
- [2] Jin R, Zhao J et al.. Application of immune checkpoint inhibitors in EGFR-mutant non-small-cell lung cancer: from bed to bench. Therapeutic advances in medical oncology. 2020. 32565926
- [3] Busakhala N, Atundo L et al.. Characteristics and Associated Survival of Patients Diagnosed With Non-Small Cell Lung Cancer in a Designated Lung Cancer Program in Western Kenya. JCO global oncology. 2025 Apr. 40184569
- [4] Trudel S, Lendvai N et al.. Antibody-drug conjugate, GSK2857916, in relapsed/refractory multiple myeloma: an update on safety and efficacy from dose expansion phase I study. Blood cancer journal. 2019 Mar 20. 30894515
- [5] Tang Q, Li H et al.. Opportunities and Challenges in the Development of Antibody-Drug Conjugate for Triple-Negative Breast Cancer: The Diverse Choices and Changing Needs. World journal of oncology. 2024 Aug. 38993251
- [6] Koshkin VS, Henderson N et al.. Efficacy of enfortumab vedotin in advanced urothelial cancer: Analysis from the Urothelial Cancer Network to Investigate Therapeutic Experiences (UNITE) study. Cancer. 2022 Mar 15. 34882781
- [7] Noto A, De Vitis C et al.. Combination therapy with anti-ErbB3 monoclonal antibodies and EGFR TKIs potently inhibits non-small cell lung cancer. Oncotarget. 2013 Aug. 23896512
- [8] Schiller JH. Adjuvant systemic therapies in early-stage non-small-cell lung cancer. Clinical lung cancer. 2003 Sep. 14641992
- [9] Della Corte CM, De Rosa C et al.. The evolving landscape of first-line and subsequent therapies in EGFR-mutated NSCLC: efficacy, resistance, and tolerability. Exploration of targeted anti-tumor therapy. 2026. 42079860
- [10] Ettorre VM, Palmieri L et al.. Clinical pharmacologic considerations for antibody-drug conjugate in gynecologic cancers. Expert review of clinical pharmacology. 2025 Jul. 40660679
- [11] Sibomana O. FDA approves Datroway: a novel therapy for HR-positive, HER2-negative metastatic breast cancer. Annals of medicine and surgery (2012). 2025 Apr. 40212175
- [12] Spring LM, Nakajima E et al.. Sacituzumab Govitecan for Metastatic Triple-Negative Breast Cancer: Clinical Overview and Management of Potential Toxicities. The oncologist. 2021 Oct. 34176192
- [13] Wu J, Kong R et al.. Can trastuzumab emtansine be replaced by additional chemotherapy plus targeted therapy for HER2-overexpressing breast cancer patients with residual disease after neoadjuvant chemotherapy?. Chinese journal of cancer research = Chung-kuo yen cheng yen chiu. 2019 Dec. 31949390
- [14] Wu Q, Su Q et al.. Magnoliae flos Overcomes EGFR-TKI Resistance in NSCLC by Enhancing EGFR Ubiquitination. Phytotherapy research : PTR. 2026 Jun. 41949384
- [15] Cai ZL, Yang HT et al.. Efficacy and safety of trastuzumab deruxtecan in patients with solid tumors: a systematic review and meta-analysis of 3 randomized controlled trials. American journal of cancer research. 2023. 37693138
- [16] Dima D, Vazquez-Martinez MA et al.. Outcomes of teclistamab in patients with relapsed/refractory multiple myeloma with prior exposure to BCMA-directed therapy: a multicenter study from the U.S. Multiple Myeloma Immunotherapy Consortium. Blood cancer journal. 2025 Jun 25. 40562770
- [17] Nandini D, Jennifer A et al.. Therapeutic Strategies for Metastatic Triple-Negative Breast Cancers: From Negative to Positive. Pharmaceuticals (Basel, Switzerland). 2021 May 12. 34065837
- [18] Zhang J, Gold KA et al.. Sorafenib in non-small cell lung cancer. Expert opinion on investigational drugs. 2012 Sep. 22725255
- [19] Zheng H, Xian H et al.. BCMA-targeted therapies for multiple myeloma: latest updates from 2024 ASH annual meeting. Journal of hematology & oncology. 2025 Mar 1. 40025529
- [20] Trastuzumab Deruxtecan Targets HER2+ Cancers. Cancer discovery. 2018 Aug. 29950345
Contact Us
Address
One Research Ct, Suite 450
Rockville, MD 20850
For General Inquiry
info@pienomial.com
