This study systematically elucidates the therapeutic evolution of ADCs in breast cancer, providing critical theoretical support for the design of next-generation antibody–drug conjugates and combination immunotherapy strategies.
Literature Overview
The article, 'Evolving antibody-drug conjugates in breast cancer from precision delivery to tumor microenvironment reprogramming,' published in the Journal of Hematology & Oncology, systematically explores the development of antibody–drug conjugates (ADCs) in breast cancer treatment, focusing on target expansion, structural optimization, resistance mechanisms, and interactions with the tumor microenvironment (TME). The article reviews the evolution from first-generation ADCs (e.g., T-DM1) to next-generation ADCs (e.g., T-DXd, SG, HER3-DXd), and deeply analyzes the dual role of the TME in ADC efficacy and resistance. It further evaluates strategies to overcome resistance, such as microenvironment-responsive linkers, immune-stimulatory payloads, and combination with immune checkpoint inhibitors.Background Knowledge
Breast cancer is a highly heterogeneous malignancy, with significant differences in treatment strategies among HER2-positive, hormone receptor-positive, and triple-negative breast cancer (TNBC) subtypes. Although targeted therapies have significantly improved outcomes for some patients, HER2-low breast cancer has long lacked effective targeted options, and resistance remains widespread. Emerging ADC targets such as TROP-2 and HER3 show clinical potential but are still limited by antigen heterogeneity, compensatory signaling pathways, and immunosuppressive TME. The core of this review lies in systematically tracing the functional expansion of ADCs from 'precision killing' to 'microenvironment remodeling,' emphasizing that the tumor microenvironment (TME) is not merely a physical barrier but can be actively reprogrammed by ADCs, offering new insights into overcoming resistance. Mechanisms such as immunogenic cell death (ICD), the bystander effect, and tumor-associated macrophages (TAMs) are key to understanding the heterogeneous efficacy of ADCs.
Research Methods and Experiments
The authors conducted a systematic review integrating data from key clinical trials, including phase III studies such as DESTINY-Breast04, DESTINY-Breast03, ASCENT, and OptiTROP-Breast01, analyzing the efficacy of different ADCs in HER2-low, TNBC, and HR+/HER2- breast cancer. Mechanistic studies were also synthesized to explore ADC-induced immunogenic cell death (ICD), such as T-DXd activating dendritic cells via the TLR4/STING pathway and promoting CD8⁺ T-cell infiltration. The study also references cutting-edge technologies such as spatial transcriptomics and multi-omics analysis to decipher the relationship between TME heterogeneity and ADC response. Furthermore, by comparing different linker types (cleavable vs. non-cleavable), payload classes (microtubule inhibitors vs. topoisomerase I inhibitors), and drug-to-antibody ratios (DAR), the impact of structural optimization on the balance between bystander effects and toxicity was revealed.Key Conclusions and Perspectives
Research Significance and Prospects
This study provides a clear roadmap for drug development: future ADCs should evolve beyond simple cytotoxic delivery to become 'smart bombs' with immunomodulatory functions. By rationally designing payloads (e.g., TLR8 agonists) and linkers, the TME can be actively reprogrammed to enhance antitumor immunity. Moreover, combining ADCs with immune checkpoint inhibitors (e.g., PD-1/PD-L1) may overcome the 'immune desert' phenotype, particularly in TNBC.
On the clinical monitoring front, the application of dynamic biomarkers (e.g., ctDNA, spatial transcriptomics) will enable precise resistance early warning and timely treatment adjustments. Additionally, digital twin modeling combined with AI-based pharmacokinetic simulation holds promise for personalized ADC dosing strategies, thereby widening the therapeutic window.
Regarding disease modeling, more clinically representative PDX or humanized mouse models are needed to evaluate the true effects of ADCs within complex TMEs. For instance, immune-humanized mice could be used to validate the synergistic mechanisms of ADC and immunotherapy combinations.
Conclusion
The evolution of antibody–drug conjugates in breast cancer marks a paradigm shift from 'precision killing' to 'microenvironment reprogramming.' Next-generation ADCs such as T-DXd and SG not only overcome the limitations of traditional targeted therapies but also actively reshape the tumor immune microenvironment by inducing immunogenic cell death. This dual mechanism opens new avenues for overcoming resistance. In the future, integrating AI-driven design, dynamic biomarker monitoring, and bispecific molecular engineering will propel ADCs toward personalized and intelligent therapy. For difficult-to-treat subtypes such as HER2-low and TNBC, combination strategies of ADCs with immunotherapy are poised to become the new standard. From bench to bedside, this study lays the foundation for building a more effective breast cancer care system, emphasizing the importance of the tumor microenvironment as a therapeutic target. By systematically dissecting resistance mechanisms and TME interactions, it provides clear direction for the design of next-generation ADCs, ultimately achieving a leap from 'cytotoxic delivery' to 'ecosystem regulation.'
