Breaking barriers in triple negative breast cancer (TNBC) - Unleashing the power of antibody-drug conjugates (ADCs)

CCL20-CCR6 signaling in tumor microenvironment: Functional roles, mechanisms, and immunotherapy targeting

Chemokine CC motif ligand 20 (CCL20) is a molecule with immunomodulatory properties that is involved in the regulation of diseases such as chronic inflammation, autoimmune diseases, and cancer. It operates by binding to its specific receptor, CC chemokine receptor type 6 (CCR6), and activating a complex intracellular signaling network. Building on its established role in inflammatory diseases, recent research has expanded our understanding of CCL20 to encompass its critical contributions to the tumor microenvironment (TME), highlighting its significance in cancer progression. Numerous studies have emphasized its prominent role in regulating immune responses. Consequently, Monoclonal antibodies against CCL20 and inhibitors of CCR6 have been successfully developed to block downstream signaling, making the CCL20-CCR6 axis a promising and critical target in the TME. This offers potential immunotherapeutic strategies for cancers. In this review, we summarize the biological consequences of CCL20-CCR6 mediated signaling, its role and mechanisms in the TME, and its potential applications. We suggest that the CCL20-CCR6 axis may be a novel biomarker for tumor diagnosis and prognosis, as well as a therapeutic target in various cancers.

LBA and LC-MS/MS based comprehensive bioanalytical methods for FDA018, a Trop-2 targeted antibody-drug conjugate

Recently, the approval of Trop-2 targeted antibody drug conjugate (ADC) has changed the dilemma of patients with advanced triple-negative breast cancer who rely on chemotherapeutics to improve their survival. FDA018, an ADC consisting of an anti-Trop-2 antibody conjugated with a topoisomerase inhibitor SN-38 via an acid-cleavable linker, is currently being investigated in clinical trials. Based on the urgent demand to evaluate the clinical pharmacokinetics of FDA018, ligand binding assays (LBAs) for the determination of SN-38-conjugated antibody and total antibody and LC-MS/MS methods for the determination of the free SN-38, its metabolite SN-38G and total SN-38 were developed. The comparability and DAR sensitivity evaluation of the ELISA strategies for SN-38-conjugated antibody and total antibody were emphasized. The sensitivity of the LC-MS/MS method for the simultaneous determination of SN-38 and SN-38G reached 0.500 ng/mL and 0.250 ng/mL, respectively. An effective solution has been proposed for the optical instability of the cleavable linker of FDA018 during the pretreatment process of biological samples. The established bioanalytical methods were comprehensively validated and the results satisfied the acceptable criteria of ICH M10. The validated bioanalytical methods have been applied to the single-dose pharmacokinetic study of FDA018 in patients with Trop-2-positive malignant tumors successfully, and the pharmacokinetic profiles of FDA018 and its constituent components were investigated.

Polygonum multiflorum Stilbene Glycoside Oligomers induce the ferroptosis of triple negative breast cancer cells

The quality control testing component and main active ingredient of Polygonum multiflorum Thunb. (P. multiflorum), known as trans-2,3,5,4'-tetrahydroxystilbene 2-O-β-D-glucopyranoside (TSG), exhibits diverse biological activities. In this study, we report, for the first time, the potent ability of TSG to induce ferroptosis in triple negative breast cancer (TNBC) cell lines and to inhibit the proliferation of TNBC cells. Treatment with TSG triggers the production of lipid peroxides, 4-hydroxynonenal (4-HNE), and reactive oxygen species (ROS) in TNBC cells, indicating the induction of ferroptosis. Both in vivo and in vitro experiments confirmed the inhibitory effects of TSG on TNBC cell proliferation and metastasis. Furthermore, we investigated the effects of other stilbene glycoside oligomers, alongside TSG, on TNBC cell lines. These compounds also demonstrated the ability to induce ferroptosis and suppress TNBC cells' proliferation and metastasis. These findings suggest that the induction of ferroptosis by TSG and related compounds could potentially serve as a promising therapeutic strategy for TNBC treatment.

Efficacy and Safety of Immunochemotherapy in Advanced Triple-negative Breast Cancer: A Meta-analysis of Randomised Clinical Trials

AIMS

Based on the existing controversial clinical research results, this study conducted a comprehensive meta-analysis of relevant literature to clarify the benefits of immunochemotherapy (ICT)-which combines immune checkpoint inhibitors and chemotherapy (CT)-for patients with advanced triple-negative breast cancer (aTNBC).

MATERILAS AND METHODS

A thorough literature search was conducted up to February 15, 2024. Subsequently, meta-analyses were performed to aggregate hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS), odds ratios (ORs) for objective response rate (ORR) and relative risks (RRs) for adverse events (AEs).

RESULTS

Six randomised clinical trials (RCTs) involving 3,105 patients met the inclusion criteria. In comparison with CT, ICT yielded significant enhancements in PFS (HR, 0.80; 95%CI: 0.73-0.87), OS (HR, 0.87; 95%CI: 0.80-0.96), and ORR (OR, 1.34; 95%CI: 1.15-1.55) in the intention-to-treat population. However, ICT also exhibited an increase in grade ≥3 AEs (RR, 1.11; 95%CI: 1.04-1.19) and severe AEs (RR, 1.40; 95%CI: 1.18-1.66). Subgroup analyses revealed that ICT significantly improved PFS (HR, 0.67; 95%CI: 0.58-0.77), OS (HR, 0.75; 95%CI: 0.64-0.87), and ORR (OR, 1.47; 95%CI: 1.16-1.84) within the PD-L1-positive subgroup, whereas no statistically significant differences were detected for PD-L1-negative population.

CONCLUSION

ICT demonstrates superior efficacy over conventional CT in the treatment of aTNBC, albeit accompanied by heightened toxicity. Notably, the assessment of PD-L1 status may serve as a valuable biomarker in discerning aTNBC patients who are particularly predisposed to derive benefit from ICT.

PROSPERO NUMBER

CRD42024513270.

Antibody-drug conjugates in elderly patients with breast cancer

Breast cancer remains a leading cause of cancer-related mortality worldwide, with elderly patients (aged >65 years) comprising a substantial portion of those affected. The treatment of breast cancer in this population is often complicated by frailty, comorbidities and polypharmacy. This review explores the application of antibody-drug conjugates (ADCs), such as trastuzumab emtansine (T-DM1), trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG), in treating breast cancer among elderly populations. The underrepresentation of older patients in clinical trials complicates efficacy and safety assessments in this group. Current evidence indicates that ADCs are both effective and tolerable in elderly patients, demonstrating improved progression-free survival (PFS) and overall survival (OS) alongside a manageable safety profile. Data from several trials like the EMILIA, TH3RESA and DestinyBreast studies demonstrate that T-DM1 and T-DXd maintained benefit in PFS and OS for HER2-positive breast cancer in older patients, despite a slight increase in adverse events. The ASCENT and TROPiCS-02 trials further confirm that SG provides significant improvements in PFS and OS in elderly patients at the cost of an increase in some toxicity. Emerging ADCs, including datopotamab deruxtecan and ARX-788, show promise but lack extensive geriatric-specific data. While the ADCs offer encouraging results in terms of efficacy and safety, with appropriate dose adjustments, further research is needed to optimize their use in elderly patients with breast cancer.

Advances in research and current challenges in the treatment of advanced HER2-low breast cancer

Human epidermal growth factor receptor 2 (HER2)-low breast cancer is defined as breast cancer with an immunohistochemistry (IHC) score of 1+ or 2+ and in situ hybridisation (ISH)-negative. The traditional HER2 classification (negative or positive) has limitations, with only 15%-20% of the breast cancer population being positive and suitable for HER2-targeted therapy. The new clinical study, DESTINY-Breast04, shows that trastuzumab deruxtecan (T-DXd) has a significant effect on advanced HER2-low breast cancers, a classification that accounts for approximately half of the advanced breast cancer population. However, the detection methods and evaluation criteria for HER2-low breast cancer have not yet been standardised, and the toxicity and resistance mechanisms associated with T-DXd therapy are still unclear. This article focuses on these issues and describes the progress and challenges of T-DXd-related therapy in the treatment of advanced breast cancer patients with low HER2 expression.

Safety profile of sacituzumab govitecan in patients with breast cancer: A systematic review and meta-analysis

BACKGROUND

Sacituzumab Govitecan (SG), a first-in-class anti-trophoblast cell surface antigen-2-directed antibody-drug conjugate (ADC), has shown clinically meaningful improvement in outcomes of patients with breast cancer (BC). However, it has also been accompanied by significant toxicity. Thus, we conducted a systematic review and meta-analysis to evaluate the safety and tolerability of SG in this patient population.

METHODS

We comprehensively searched PubMed, Embase, and Cochrane databases, and ASCO and ESMO websites for clinical trials (CTs) assessing the safety of SG in BC patients. All analyses were performed in R software (v.4.2.2) using random effects models. Heterogeneity was assessed using I2 test.

RESULTS

Seven studies - three randomized clinical trials (RCTs) and four single-arm phase I/II - were included, comprising 928 patients receiving SG and 576 on treatment of physician's choice (TPC). Most patients had triple negative BC (54.4 %, n = 505), metastatic disease (89.8 %, n = 833), and were heavily pretreated (at least two lines of prior therapy). Most common all-grade adverse events (AEs) were: neutropenia (70 %, 95 % CI, 64-76 %), followed by nausea (62 %, 95 % CI, 55-68 %), diarrhea (54 %, 95 % CI 47-60 %) and anemia (51 %, 95 % CI, 38-65 %). Regarding high-grade AEs, 46 % of patients developed grade ≥3 neutropenia. Compared to TPC, we observed a higher risk of neutropenia (OR 3.11, 95 % CI 1.62-5.99, I2 = 81 %; p < 0.001), diarrhea (OR 6.82, 95 % CI 3.99-11.66, I2 = 64 %; p < 0.001) and anemia (OR 2.26, 95 % CI 1.20-4.27, I2 = 78 %; p = 0.012) for those on SG. Dose reductions and treatment discontinuation were reported in 22 % and 4 % of patients, respectively, and 19 deaths (2 %) were documented. Most of them were not deemed to be treated-related.

CONCLUSION

This systematic review and meta-analysis provides extensive data on the safety and management of SG toxicity in BC patients across clinical trials. Concerning rates of neutropenia, nausea diarrhea, and anemia were reported. We highlight the need for protocols establishing prophylactic measures and strategies to mitigate SG-related toxicity.

Pleiotropic anti-cancer activities of novel non-covalent thioredoxin reductase inhibitors against triple negative breast cancer

Mounting evidence shows that tumor growth and progression rely on thioredoxin reductase 1 (TXNRD1)-mediated detoxification of oxidative stress that results from deregulated metabolism and mitogenic signaling in tumors. TXNRD1 levels are significant higher in triple negative breast cancer (TNBC) compared to normal tissue, making TXNRD1 a compelling TNBC therapeutic target. Despite the many attempts to generate TXNRD1 inhibitors, all known and reported compounds inhibiting TXNRD1 are problematic; they interact with TXNRD1 irreversibly and non-specifically resulting in numerous adverse side effects. Recently, a series of breakthrough studies identified a novel regulatory site, the 'doorstop pocket', in Schistosoma mansoni thioredoxin glutathione reductase, a TXNRD-like enzyme and an established drug target for the human parasitic infection, schistosomiasis. This discovery underpins the development of new first-in-class non-covalent inhibitors for this family of enzymes. Our data show that novel non-covalent TXNRD inhibitors (TXNRD(i)s) are potent dose-dependent inhibitors of viability in cellular models of TNBC. TXNRD(i)s attenuate several aggressive cancer phenotypes such as, clonogenic survival, mammosphere forming efficiency, invasion, and TXNRD-related gene expression in TNBC cells. TXNRD(i)s engage and inhibit TXNRD1 in live TNBC cells and xenograft tumors, thus supporting the mechanism of action at a cellular level. More importantly, TXNRD(i)s attenuated tumor growth in a preclinical MDA-MB-231 TNBC xenograft mouse model. Although additional optimization for TXNRD(i)s' potency is warranted, these results may open a new avenue for the development of novel small molecule therapeutics for TNBC.

Prodrugs in Oncology: Bioactivation and Impact on Therapeutic Efficacy and Toxicity

A prodrug is a molecule that lacks pharmacological activity, but upon enzymatic bioactivation, it can generate a therapeutically active molecule. The primary reason behind the design of a prodrug is to help circumvent challenges associated with the physicochemical properties of a drug molecule, such as solubility, absorption, distribution, and instability. Chemotherapy has been at the forefront of cancer treatment for over 70 years due to its ability to target rapidly proliferating tumor cells. However, a major concern with conventional chemotherapy is the lack of selectivity and its associated side toxicity, which can severely impact patients' quality of life. In oncology, prodrugs have been explored to enhance the bioavailability, improve efficacy, and minimize systemic toxicity of chemotherapeutic agents. Prodrugs activated by enzymes unique to a tumor microenvironment can significantly increase targeted delivery of chemotherapeutic drugs. This review aims to highlight commonly used chemotherapeutic prodrugs, including both alkylating and non-alkylating agents, and discuss their clinical relevance, mechanisms of bioactivation, and toxicity concerns.

Molecular Basis of Breast Tumor Heterogeneity

Breast cancer (BC) is a profoundly heterogenous disease, with diverse molecular, histological, and clinical variations. The intricate molecular landscape of BC is evident even at early stages, illustrated by the complexity of the evolution from precursor lesions to invasive carcinoma. The key for therapeutic decision-making is the dynamic assessment of BC receptor status and clinical subtyping. Hereditary BC adds an additional layer of complexity to the disease, given that different cancer susceptibility genes contribute to distinct phenotypes and genomic features. Furthermore, the various BC subtypes display distinct metabolic demands and immune microenvironments. Finally, genotypic-phenotypic correlations in special histologic subtypes of BC inform diagnostic and therapeutic approaches, highlighting the significance of thoroughly comprehending BC heterogeneity.

Recent Advances in Immunotherapy and Targeted Therapy of Triple Negative Breast Cancer

The truancy of representation of the estrogen, progesterone, and human epidermal growth factor receptors occurs during TNBC. TNBC is recognized for the upper reappearance and has a poorer diagnosis compared with rest breast cancer (BC) types. Presently, as such, no targeted therapy is approved for TNBC and treatment options are subjected to chemotherapy and surgery, which have high mortality rates. Hence, the current article focuses on the scenario of TNBC vital pathways and discusses the latest advances in TNBC treatment, including immune checkpoint inhibitors (ICIs), PARP suppressors, and cancer vaccines. Immunotherapy and ICIs, like PD 1 and PD L1 suppressors, displayed potential in clinical trials (CTs). These suppressors obstruct the mechanisms which allow tumor cells to evade the system thereby boosting the body's defense against TNBC. Immunotherapy, either alone or combined with chemotherapy has demonstrated patient outcomes such as increased survival rates and reduced treatment-related side effects. Additionally, targeted therapy approaches include BRCA/2 mutation poly ribose polymerase inhibitors, Vascular Endothelial Growth Factor Receptor (VEGFR) inhibitors, Epidermal growth factor receptor inhibitors, Fibroblast growth factor inhibitors, Androgen Receptor inhibitors, PIK3/AKT/mTOR pathway inhibitors, Cyclin-dependent kinase (CDK) inhibitors, Notch signaling pathway inhibitors, Signal transducer and activator of transcription 3 (STAT3) signaling pathway inhibitors, Chimeric antigen receptor T (CAR-T) cell therapy, Transforming growth factor (TGF) -β inhibitors, Epigenetic modifications (EPM), Aurora Kinase inhibitors and antibody-drug conjugates. We also highlight ongoing clinical trials and potential future directions for TNBC therapy. Despite the challenges in treating TNBC, recent developments in understanding the molecular and immune characteristics of TNBC have opened up new opportunities for targeted therapies, which hold promise for improving outcomes in this aggressive disease.

Modeling intratumor heterogeneity in breast cancer

Reduced therapy response in breast cancer has been correlated with heterogeneity in biomarker composition, expression level, and spatial distribution of cancer cells within a patient tumor. Thus, there is a need for models to replicate cell-cell, cell-stromal, and cell-microenvironment interactions during cancer progression. Traditional two-dimensional (2D) cell culture models are convenient but cannot adequately represent tumor microenvironment histological organization,in vivo3D spatial/cellular context, and physiological relevance. Recently, three-dimensional (3D)in vitrotumor models have been shown to provide an improved platform for incorporating compositional and spatial heterogeneity and to better mimic the biological characteristics of patient tumors to assess drug response. Advances in 3D bioprinting have allowed the creation of more complex models with improved physiologic representation while controlling for reproducibility and accuracy. This review aims to summarize the advantages and challenges of current 3Din vitromodels for evaluating therapy response in breast cancer, with a particular emphasis on 3D bioprinting, and addresses several key issues for future model development as well as their application to other cancers.

Latest Therapeutical Approaches for Triple-Negative Breast Cancer: From Preclinical to Clinical Research

Triple-negative breast cancer (TNBC) represents roughly one-sixth of all breast cancer patients, but accounts for 30-40% of breast cancer deaths. Due to the lack of typical biomarkers exploited clinically for breast cancer, it remains very difficult to treat. Moreover, its intrinsic high heterogeneity and proneness to become resistant to the drugs administered makes the treatment management very challenging for oncologists. Herein, we outline the different therapies used currently for TNBC and list the ongoing clinical trials to provide an overview of the most recent TNBC therapeutic landscape. In addition, we highlight the emerging therapies in the preclinical stage that hold the most promise, such as epigenetic modulators, CRISPR, miniproteins, radioconjugates, cancer vaccines, and PROTACs. Moreover, we navigate through the existing limitations and challenges which hamper the development of new and more effective treatments for TNBC. Lastly, we point to emerging new directions that may revolutionize future therapy for TNBC.

PTPN20 promotes metastasis through activating NF-κB signaling in triple-negative breast cancer

BACKGROUND

Cancer metastasis remains a major challenge in the clinical management of triple-negative breast cancer (TNBC). The NF-κB signaling pathway has been implicated as a crucial factor in the development of metastases, but the underlying molecular mechanisms remain largely unclear.

METHODS

PTPN20 expression was evaluated using data from the Sweden Cancerome Analysis Network-Breast and The Cancer Genome Atlas database, as well as by western blotting and immunohistochemistry in 88 TNBC patients. The ability of PTPN20 to activate NF-κB was assessed by luciferase reporter assays. The effects of PTPN20 overexpression and knockdown via short hairpin RNA were examined in TNBC cell lines by wound healing and transwell matrix penetration assays. Additionally, we analyzed the growth and metastasis abilitiy of 4T1 xenograft tumors in nude mice.

RESULTS

PTPN20 levels were elevated in TNBC cell lines and patient samples compared to controls, and higher protein levels correlated with metastasis-free survival. Overexpression of PTPN20 enhanced migration and invasion in vitro, and promoted lung metastasis in vivo. Our finding revealed that PTPN20 activates NF-κB signaling by dephosphorylating p65 at Ser468, preventing its binding to COMMD1, thereby protecting p65 from degradation. Downregulation of PTPN20 effectively inhibit, while p65 S468A mutant restored the migratory and invasive abilities of TNBC cells.

CONCLUSIONS

Collectively, our results demonstrate that PTPN20 plays a critical role in TNBC metastasis through the activation of NF-κB signaling. We propose that PTPN20 may serve as a novel prognostic marker and potential therapeutic target for the treatment of TNBC.

Understanding the chemistry & pharmacology of antibody-drug conjugates in triple-negative breast cancer with special reference to exatecan derivatives

In the spectrum of breast malignancies, triple-negative breast cancer is the most widely spreading subtype of breast cancer due to a low availability of therapeutic remedies. Recently, antibody-drug conjugates dramatically resolved the landscape for the treatment of triple-negative breast cancer. This review mainly focuses on the chemistry, structure, mechanism of action, and role of antibody-drug conjugates in triple-negative breast cancer. Datopotecan Deruxtecan (Dato-DXd) is a new-generation ADC showing encouraging results for TNBC. In this review, we have also emphasized TROP-2-directed Datopotamab deruxtecan ADCs to treat triple-negative breast cancer, its synthesis, mechanism of action, pharmacokinetics, pharmacodynamics, adverse events, and their ongoing clinical trials.

Research on therapeutic clinical trials including immunotherapy in triple-negative breast cancer: a bibliometric analysis

Background

Breast cancer, particularly triple-negative (TNBC), is a leading malignancy with aggressive traits and high metastasis rates. Clinical trial is an important tool for optimizing therapeutic strategies in the evaluation of the safety and efficacy for TNBC. Our bibliometric study of TNBC clinical trials aims to assess therapeutic strategies, identify trends, and explore advancements in treatment. We focus on mapping knowledge development, including key research entities and topics, and analyzing research trends and emerging methods. This analysis intends to inform future research, especially in personalized and precision medicine for TNBC.

Methods

We selected publications on clinical trials for the treatment of TNBC from 1997 to 2024 in the Web of Science Core Collection (WoSCC). After an initial screening, we downloaded key data including titles, publication years, authors, countries, institutional affiliations, journals, keywords, and abstracts, and saved them in BibTex format. We then conducted a bibliometric analysis using Bibliometrix in R and VOSviewer to illustrate the prospects, highlights, and trends of TNBC treatment options. Furthermore, to emphasize the hot topics in TNBC treatment strategies, we performed a bibliometric analysis of immunotherapy using the same approach.

Results

1907 publications were included, most of which were from China, Italy, and the United States. The number of annual publications has increased dramatically since 2010. The focus of TNBC clinical trial research has shifted from understanding the biology, such as breast cancer subtyping and genotyping, to novel therapeutic approaches. The major advancement in clinical trials is the switch from late-stage palliative treatment to early preoperative neoadjuvant therapy, as more TNBC cases are discovered at an early stage. Immunotherapy is also highlighted with additional alternatives for advanced or metastasized TNBC, such as targeted inhibitors with unusual mutation rates and antibody drug conjugates (ADC).

Conclusions

This investigation made it apparent how immunotherapy has recently made major advancements in TNBC treatment plans and how ADCs, or targeted therapies, are currently popular for TNBC. By identifying significant papers, comprehending trending topics, and collaborating across multiple disciplines, this study may accelerate research on TNBC therapy options.

Tuning Immune-Cold Tumor by Suppressing USP10/B7-H4 Proteolytic Axis Reinvigorates Therapeutic Efficacy of ADCs

Tuning immune-cold tumor hot has largely attracted attention to improve cancer treatment, including immunotherapy and antibody-drug conjugates (ADCs). Utilizing multiomic analyses and experimental validation, this work identifies a pivotal role for the USP10/B7-H4 proteolytic axis in mediating the interplay between tumor immune responses and ADC efficacy, particularly for sacituzumab govitecan (SG) in treating triple negative breast cancers (TNBCs). Mechanistically, the inhibition of autocrine motility factor receptor (AMFR)-mediated ubiquitylation of B7-H4 by the deubiquitinase USP10 leads to the stabilization of B7-H4, which suppresses tumor immune activity and reduces SG treatment effectiveness. Pharmacological inhibition of USP10 promotes the degradation of B7-H4, enhancing tumor immunogenicity and consequently improving the tumor-killing efficacy of SG. In preclinical TNBC models, suppression of USP10/B7-H4 proteolytic axis is effective in increasing SG killing efficacy and reducing tumor growth, especially for the tumors with the USP10high/B7-H7high signature. Collectively, these findings uncover a novel strategy for targeting the immunosuppressive molecule B7-H4 for cancer therapy.

Gastrointestinal Toxicity of Antibody Drug Conjugates (ADCs) in Metastatic Breast Cancer: A Pooled Analysis

Trastuzumab emtansine (T-DM1), sacituzumab govitecan (SG), and trastuzumab deruxtecan (T-DXd) are three ADCs approved for the treatment of metastatic breast cancer (MBC). Since gastrointestinal toxicities have been commonly observed with these drugs in clinical trials, a pooled analysis evaluating gastrointestinal adverse events (AEs) in patients with MBC treated with ADCs in clinical trials was performed. PubMed, Embase, and the Cochrane Library were searched from inception until May 2023 for phase II and III clinical trials reporting frequency and severity of gastrointestinal AEs during treatment with ADCs. Data were retrieved for nausea, vomiting, diarrhea, constipation, and abdominal pain: overall and grade 3-4 toxicity rates according to NCI-CTCAE were collected and expressed as proportions. A pre-specified subgroup analysis according to the agent was also carried out. Fourteen studies, comprising 5608 patients, were included in the analysis. Gastrointestinal AEs were frequently registered with SG and T-DXd. A significantly higher frequency of nausea (65.6% with SG, 75% with T-DXd), vomiting (43.7% with SG, 45% with T-DXd), and diarrhea (59.7% with SG, 29% with T-DXd) was noticed with these ADCs compared to TDM-1. Furthermore, diarrhea was more frequently associated with SG (grade 3 in 7.5% of patients), while constipation and abdominal pain were less common. Gastrointestinal AEs, notably nausea and diarrhea, were frequently reported by MBC patients treated with SG and T-DXd in clinical trials. Since these ADCs are administered continuously until disease progression or occurrence of unbearable AEs, gastrointestinal toxicity may have a negative impact on patient quality of life. Therefore, appropriate management of gastrointestinal AEs is mandatory to ensure treatment efficacy and adherence.