Trop2 and its overexpression in cancers: regulation and clinical/therapeutic implications

[68Ga]Ga-NOTA-T4 ImmunoPET imaging for evaluating TROP2 expression in patients with solid tumors

PURPOSE

Gallium-68 (68Ga)-labeled [68Ga]Ga-NOTA-T4 immuno-positron emission tomography (immunoPET) holds great promise as a non-invasive technique for visualizing the expression of trophoblast cell-surface antigen 2 (TROP2). This approach may potentially assist in making clinical decisions regarding TROP2-targeted therapies. The present study aims to evaluate the utility of [68Ga]Ga-NOTA-T4 PET/CT in detecting TROP2 expression levels, diagnosing primary tumors and metastatic lesions. Additionally, it conducts a direct comparison with fluorine-18-labeled fluorodeoxyglucose ([18F]FDG) PET/CT.

METHODS

Participants with solid tumors who underwent [68Ga]Ga-NOTA-T4 PET/CT scans were prospectively recruited between October 2023 and August 2024. A subset of these participants also received [18F]FDG PET/CT. The uptake in physiological organs was quantified using the mean standardized uptake value (SUVmean). Positive lesions were identified through visual assessments and further quantified using the maximum standardized uptake value (SUVmax) and the target-to-background ratio (TBR). The TBR was calculated by dividing the SUVmax of the lesion by the SUVmean of the background, where the brain background was used for cerebral lesions and the blood pool for other lesions. TROP2 expression levels were evaluated via immunohistochemical (IHC) tumor proportion score (TPS). Biodistribution, lesion detectability, and the correlation with TROP2 were analyzed for both tracers using appropriate statistical methods.

RESULTS

A total of 26 patients (mean age: 63 ± 10 years; 13 females) were included in the study. [68Ga]Ga-NOTA-T4 demonstrated high uptake in the kidneys, pancreas, thyroid, and submaxillary gland, while showing low uptake in the brain, muscle, and bone. Both tracers successfully detected all 19 primary/recurrent tumors. However, [68Ga]Ga-NOTA-T4 presented lower SUVmax and TBR compared to [18F]FDG (1.93 [1.36, 2.58] vs. 11.37 [6.45, 13.15], P < 0.001; 2.83 [2.17, 3.74] vs. 6.95 [5.24, 11.27], P = 0.03, respectively). [68Ga]Ga-NOTA-T4 identified fewer suspected metastases but detected two brain metastases that were missed by [18F]FDG. TROP2 TPS was positively correlated with [68Ga]Ga-NOTA-T4 SUVmax (r = 0.85, P = 0.002) and TBR (r = 0.66, P = 0.030), while no significant correlation was observed for [18F]FDG.

CONCLUSION

[68Ga]Ga-NOTA-T4 PET/CT emerges as a promising non-invasive tool for assessing TROP2 expression levels and diagnosing solid tumors. In certain specific cases, it exhibits potential advantages over [18F]FDG.

TROP2 expression and therapeutic targeting in uterine carcinosarcoma

OBJECTIVE

Uterine carcinosarcoma (UCS) is a rare and aggressive type of endometrial carcinoma (EC), and novel therapeutic strategies are needed. We sought to assess TROP2 expression in archival UCSs and TROP2 antibody-drug conjugate (ADC) targeting in patient-derived UCS organoid (PDO) and xenograft (PDX) models.

METHODS

TROP2 protein (immunohistochemistry) and mRNA (qRT-PCR) expression were assessed in 72 archival UCS tissues. Nine UCS PDO models were established and molecularly characterized by panel sequencing; then, TROP2 levels were determined and the efficacy of the TROP2 ADC sacituzumab govitecan (SG) defined in the UCS PDO and PDX models (n = 2).

RESULTS

TROP2 protein and mRNA expression were detected in ≥90 % of primary UCSs, and those with a predominant carcinomatous component or with homologous differentiation had higher TROP2 expression than those with a predominant sarcomatous component or with heterologous differentiation (p < 0.001 and p = 0.022, respectively). UCS PDOs displayed TROP2 expression and molecular profiles (median 88 %, range 50-100 % of mutation in primary UCSs present in PDOs) reflective of their respective primary UCSs. All 9 UCS PDOs responded in a dose-dependent manner to SG treatment, with a median IC50 of 167.7pM (range 51.4pM-3.2 nM). In addition, both UCS PDX models with high and low TROP2 protein expression had a significant reduction in tumor volume with SG treatment (p = 0.03 and p = 0.02, respectively).

CONCLUSIONS

We demonstrate that the majority of UCSs have detectable TROP2 expression. Our findings on the SG response in UCS PDO and PDX models warrant further studies on TROP2 targeting for patients with this aggressive disease.

Immune Checkpoint Inhibitors and Antibody-Drug Conjugates in Urothelial Carcinoma: Current Landscape and Future Directions

BACKGROUND/OBJECTIVES

Urothelial carcinoma (UC) treatment has been transformed by immunotherapy and antibody-drug conjugates (ADCs). This review evaluates the current evidence for these approaches and identifies future directions.

METHODS

We conducted a structured review of clinical trials, meta-analyses, and guidelines published until early 2025.

RESULTS

Immune checkpoint inhibitors have established benefits across multiple settings: post-platinum therapy (pembrolizumab, nivolumab), maintenance therapy (avelumab), adjuvant settings for high-risk muscle-invasive disease (nivolumab), and BCG-unresponsive non-muscle-invasive disease (pembrolizumab). Enfortumab vedotin (targeting Nectin-4) has proven effective in post-platinum/post-immunotherapy. Most significantly, enfortumab vedotin plus pembrolizumab has redefined first-line treatment with unprecedented survival benefits (median OS 31.5 months vs. 16.1 months with chemotherapy; HR 0.47), and nivolumab plus gemcitabine-cisplatin improved outcomes in cisplatin-eligible patients. Key challenges include managing unique toxicity profiles, optimizing treatment sequencing, and developing reliable biomarkers.

CONCLUSIONS

Combination approaches offer the most promising path forward, with future research needed on resistance mechanisms, biomarker development, and expanding these therapies to earlier disease stages.

Biologics for novel driver altered non-small cell lung cancer: potential and pitfalls

Precision medicine has revolutionized clinical paradigm of lung cancer (LC) patients optimizing therapeutical options on the basis of molecular fingerprinting of tumor cells. The advent of the genomic era contributed to the widespread diffusion of sequencing technologies laying the basis for the approval of an increasing number of clinically relevant predictive biomarkers in clinical settings. In the rapidly evolving scenario of predictive biomarkers, mandatory testing genes demonstrated a statistically significant clinical benefit in LC patients elected to molecular tests, but emerging biomarkers are under investigation to raise the bar in the clinical management of LC patients. To date, promising IHC-based predictive biomarkers emerged as potentially integrative tools in the panel of clinically approved biomarkers. On this basis, genomic, transcriptomic and proteomic data are gaining ground toward "3D" biology" supporting the need of a multidimensional analysis of tumor cells to clinically stratify LC patients. Here we sought to overview the most promising biomarkers investigated in clinical trials to be integrated into diagnostic panel of predictive biomarkers tools for NSCLC patients.

Multi-omic profiling in breast cancer: utility for advancing diagnostics and clinical care

INTRODUCTION

Breast cancer remains a major global health challenge. While advances in precision oncology have contributed to improvements in patient outcomes and provided a deeper understanding of the biological mechanisms that drive the disease, historically, research and patients' allocation to treatment have heavily relied on single-omic approaches, analyzing individual molecular dimensions such as genomics, transcriptomics, or proteomics. While these have provided deep insights into breast cancer biology, they often fail to offer a complete understanding of the disease's complex molecular landscape.

AREAS COVERED

In this review, the authors explore the recent advancements in multi-omic research in the realm of breast cancer and use clinical data to show how multi-omic integration can offer a more holistic understanding of the molecular alterations and their functional consequences underlying breast cancer.

EXPERT OPINION

The overall developments in multi-omic research and AI are expected to complement precision diagnostics through potentially refining prognostic models, and treatment selection. Overcoming challenges such as cost, data complexity, and lack of standardization is crucial for unlocking the full potential of multi-omics and AI in breast cancer patient care to enable the advancement of personalized treatments and improve patient outcomes.

Management approaches for recurrent or metastatic head and neck squamous cell carcinoma after anti-PD-1/PD-L1 immunotherapy

Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer globally. For patients with recurrent or metastatic (R/M) HNSCC, immunotherapy represents an important advance in clinical practice as an effective and widely used first-line treatment. However, drug resistance following immunotherapy is an emerging problem and, despite the success of immunotherapy in R/M HNSCC, a proportion of patients will become immunotherapy resistant. The mechanisms of immunotherapy resistance are not yet fully understood and subsequent treatment options are limited. Therefore, there is an unmet need for effective and well tolerated treatments for patients who develop immunotherapy-resistant HNSCC. In this review, we address these challenges by summarizing the current definitions of immunotherapy resistance (primary and acquired resistance) as well as knowledge of the mechanisms of resistance to immunotherapy in R/M HNSCC. We then review available clinical data on treatment strategies, including rechallenge with immunotherapy, chemotherapy ± cetuximab, other targeted treatments, antibody-drug conjugates, and bispecific antibodies. We also investigate future research directions by reviewing ongoing clinical trials. Our review shows that the optimal therapeutic strategy for patients with R/M HNSCC remains unclear. While many therapies have reported promising preliminary results, prospective clinical trials are required to support their adoption in clinical practice. In particular, it appears that immunotherapy and antibody-drug conjugates have high potential in this setting. Our review also highlights the importance of further investigation of the mechanisms underlying immunotherapy-resistant R/M HNSCC, to inform selection of optimal therapeutic strategies on an individual patient basis and improve patient outcomes.

Phase II Parallel Arm Study of Sacituzumab Govitecan-Hziy in Patients With Advanced Thymoma or Thymic Carcinoma

BACKGROUND

Thymic epithelial tumors (TETs), including thymoma and thymic carcinoma, are rare thoracic tumors of the anterior mediastinum. For those with advanced disease, platinum-based chemotherapy is used as first-line treatment. However, there is no standard regimen established for TET at progression after initial therapy, and treatment options for advanced/recurrent TETs are limited. Trop-2, a transmembrane glycoprotein, is overexpressed in solid tumors including thymomas and thymic carcinomas. Sacituzumab govitecan-hziy, a Trop-2-directed antibody-drug conjugate, has shown efficacy and safety in several tumors including breast cancer. The overexpression of Trop-2 in TETs and the clinical efficacy in other malignancies provide rationale for exploring its use in thymoma and thymic carcinoma.

METHODS

This open-label, single-arm, parallel cohort, multi-center study assesses the safety and efficacy of sacituzumab govitecan-hziy in patients with advanced thymoma (cohort A) and thymic carcinoma (cohort B) who have received at least 1 prior line of systemic therapy (NCT06248515). The study employs a Simon optimal 2-stage design, enrolling patients with adequate performance status, measurable disease, and adequate organ function. Sacituzumab govitecan-hziy is administered at a fixed dose of 10 mg/kg weekly on days 1 and 8 of 21-day cycles until disease progression or unacceptable toxicity. Follow-up continues every 6 months for 2 years postdiscontinuation. Archival tissue is obtained prior to initiation of study treatment with an optional biopsy at the time of progression. In cases where archival tissue is not available, a fresh biopsy is obtained at baseline. The primary endpoint is investigator-assessed response rate using Response Evaluation Criteria in Solid Tumors v1.1 (RECIST) criteria, with tumor imaging assessments every 2 cycles during the first 3 months and every 3 cycles thereafter. Secondary endpoints comprise adverse events by Common Terminology Criteria for Adverse Events v5.0, median and 6-month progression-free survival, duration of response, and overall survival. For each cohort, 9 patients will be enrolled. If 0 of the 9 achieve a response, no further patients will be enrolled in that cohort. If 1 or more of the first 9 patients has a response, accrual will continue until a total of 17 patients have been enrolled in that cohort.

The Mode of Action and Clinical Outcomes of Sacituzumab Govitecan in Solid Tumors

Sacituzumab govitecan (SG), a trophoblast cell-surface antigen-2 (Trop-2)-directed antibody-drug conjugate, is currently approved to treat metastatic triple-negative breast cancer and HR+/HER2- breast cancer and is under clinical investigation for a range of other tumor types. This review describes its mode of action, development, and clinical outcomes. SG is composed of SN-38 (a topoisomerase I inhibitor derived from irinotecan) covalently linked to an anti-Trop-2 mAb (sacituzumab; hRS7) via a hydrolyzable CL2A linker. SN-38 was chosen due to its potent antitumor activity; CL2A occupies the most effective position on SN-38 for maintaining stability during transport, with pH-sensitive payload release in the tumor, and the antigen target (Trop-2) is highly expressed on many solid tumors. SG has an ∼8:1 drug-to-antibody ratio and delivers therapeutic SN-38 concentration to Trop-2+-expressing tumor cells via rapid internalization and efficient payload release. Free SN-38 can subsequently enter the tumor microenvironment and kill adjacent tumor cells with or without Trop-2 expression (bystander effect). SN-38 induces DNA breakage and inhibits nucleic acid synthesis via a drug-induced topoisomerase 1:DNA complex that interferes with cell proliferation, causing apoptosis. Dose-finding studies support SG 10 mg/kg on days 1 and 8 of a 21-day cycle as the monotherapy dose for clinical use; this was determined by therapeutic index improvement based on efficacy and safety. Payload-linker dynamics and SG potency ensure continued tissue penetration. Neutropenia and diarrhea are the most common grade ≥3 treatment-emergent adverse events with SG, but they are manageable. The efficacy of SG has been demonstrated across a broad spectrum of solid tumors.

Structural requirements of isoform-specific inhibitors of Akt: Implications in the development of effective cancer treatment strategies

Akt, also known as protein kinase-B, is an important therapeutic target in the treatment of cancer due to its pivotal roles in the signaling pathways that regulate various hall-mark features of cancer cells such as cell growth, survival, migration, differentiation, and metabolism. The three closely related isoforms of Akt viz., Akt1, Akt2, and Akt3 exhibit distinct physiological roles that affect cellular behavior and tumor development, making isoform selectivity a crucial driving factor in the design and development of inhibitors. This review outlines key amino acids and their structural traits in Akt isoforms, potentially dictating isoform selectivity. We present an analysis of existing structure-activity relationship data of covalent-allosteric Akt inhibitors to shed light on isoform selectivity. Additionally, a brief review of potential predictive biomarkers in enhancing the therapeutic efficacy of Akt inhibitors is presented. Identifying biomarkers that can reliably predict patient response to treatment is crucial for personalizing cancer therapies and improving overall treatment outcomes. By integrating predictive biomarker identification with the ongoing development of isoform-selective Akt inhibitors, it is plausible to establish a foundation for more precise and efficacious interventions in cancer therapy.

Novel Amanitin-Based Antibody-Drug Conjugates Targeting TROP2 for the Treatment of Pancreatic Cancer

Trophoblast cell surface antigen 2 (TROP2) exhibits aberrant expression in pancreatic cancer, correlating with metastasis, advanced tumor stage, and poor prognosis in patients with pancreatic ductal adenocarcinoma. TROP2 has been recognized as a promising therapeutic target for antibody-drug conjugates (ADC), as evidenced by the approval of the anti-TROP2 ADC Trodelvy for the treatment of triple-negative breast cancer (TNBC). In this study, we report the generation of novel second-generation amanitin-based ADCs (ATAC) targeting TROP2, comprising the humanized RS7 antibody of Trodelvy (hRS7) and the highly potent payload amanitin. The specific in vitro binding, efficient antigen internalization, and high cytotoxicity of hRS7 ATACs with EC50 values in the picomolar range in TROP2-expressing cells constituted the foundation for preclinical in vivo evaluation. The hRS7 ATACs demonstrated a significant reduction in tumor growth in vivo in subcutaneous xenograft mouse models of pancreatic cancer and TNBC at well-tolerated doses. The antitumor efficacy correlated with the level of TROP2 expression on the tumors and the in vivo tumor uptake of the ATACs. The long half-life of 9.7 to 10.7 days of hRS7 ATACs without premature payload release in serum supported a high therapeutic index. Notably, the efficacy of the hRS7 ATACs was superior to that of Trodelvy with complete tumor eradication in both refractory pancreatic cancer and TNBC xenograft models. In summary, hRS7 ATACs represent a highly effective and well-tolerated targeted therapy, and our data support their development for pancreatic cancer and other TROP2-expressing tumors.

[99mTc]Tc-MY6349 Probe for Trop2-Targeted SPECT Imaging: From Preclinical to Pilot Clinical Study

The trophoblast cell-surface antigen 2 (Trop2) is markedly overexpressed in breast cancers, with a particularly high incidence in triple-negative breast cancer. The therapeutic relevance of Trop2 expression is underscored by the approval of an antibody-drug conjugate for triple-negative breast cancer treatment. However, there is no a predictive technique for accurate whole-body mapping of Trop2 expression in patients. In this study, we developed a novel Trop2-specific molecular probe, [99mTc]Tc-MY6349, and evaluated its safety and feasibility for detecting Trop2 expression in breast cancer using SPECT/CT imaging. Methods: Trop2 expression in different breast cancer cell lines was assessed via immunofluorescence and flow cytometry. The Trop2-specific nanobody MY6349 was site-specifically labeled with 99mTc via a C-terminal GGGC tag, and its binding affinity to the Trop2 receptor was tested in vitro. The in vivo tumor uptake and distribution of [99mTc]Tc-MY6349 were examined through SPECT imaging and biodistribution studies. Furthermore, a pilot clinical study of [99mTc]Tc-MY6349 SPECT/CT was conducted in 8 patients with breast cancer, and the results were compared with [18F]FDG PET/CT. Results: [99mTc]Tc-MY6349 achieved a greater than 95% radiochemical purity after purification. In vitro and in vivo experiments demonstrated the binding specificity of [99mTc]Tc-MY6349 to the Trop2 receptor. In vivo imaging and biodistribution studies revealed a significant correlation between tumor uptake and Trop2 expression levels. In the pilot clinical study, SPECT imaging with [99mTc]Tc-MY6349 successfully detected Trop2-positive tumors 15 min after tracer injection. Delayed imaging showed reduced uptake in normal organs but sustained retention of [99mTc]Tc-MY6349 in tumors. Importantly, [99mTc]Tc-MY6349 SPECT/CT imaging highlighted Trop2 expression heterogeneity and visualized primary and metastatic lesions with a favorable tumor-to-background ratio in breast cancer. Conclusion: [99mTc]Tc-MY6349 was successfully prepared and exhibited a high binding affinity and Trop2 specificity. The pilot clinical study validated the safety and feasibility of [99mTc]Tc-MY6349 SPECT/CT for detecting Trop2 expression in vivo in patients with breast cancer. This imaging modality could complement existing methods, aiding in the guidance of Trop2-targeted therapies and advancing personalized treatment while also promoting the application of SPECT/CT nuclear medicine imaging technology.

Phytochemicals as Chemo-Preventive and Therapeutic Agents Against Bladder Cancer: A Comprehensive Review

Bladder cancer has a high incidence worldwide and is characterized by a high recurrence rate, metastatic potential, and a significant socioeconomic burden. Conventional treatment modalities usually exhibit serious adverse complications, which also negatively affect patients' quality of life. In the context of exploring new treatment approaches with fewer side effects, the utilization of natural compounds as alternative and/or complementary therapeutic options seems appealing. In the present study, the potential use and effects of various bioactive phytochemicals, including curcumin, resveratrol, epigallocatechin, genistein, and several others, in bladder cancer treatment are thoroughly reviewed. A special focus is given to their potential to beneficially modulate important molecular signaling pathways and mechanisms affecting cell survival, proliferation, migration, and apoptosis, which play a crucial role in the pathogenesis of bladder cancer, such as the PI3K/AKT/mTOR, Ras/Raf/MEK/MAPK, Wnt/β-Catenin, Notch, Hedgehog, Hippo, JAK2/STAT3, and PAF/PAF-receptor pathways. Nevertheless, most studies have been conducted in cell cultures and animal models. Due to differences in genetics and metabolism, more clinical trials are needed to ensure the bio-efficacy of these phytochemicals in humans.

Advances in adoptive cell therapies in small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive tumor characterized by early metastasis and resistance to treatment, making it a prime target for therapeutic investigation. The current standard of care for frontline treatment involves a combination of chemotherapeutic agents and immune checkpoint inhibitors (ICIs), though durability of response remains limited. The genetic heterogeneity of SCLC also complicates the development of new therapeutic options. Adoptive cell therapies show promise by targeting specific mutations in order to increase efficacy and minimize toxicity. There has been significant investigation in three therapeutic classes for application towards SCLC: antibody drug conjugates (ADCs), bispecific T-cell engagers (BiTEs), and chimeric antigen receptor (CAR)-T cell therapies. This review summarizes the recent advances and challenges in the development of adoptive cell therapies. Genetic targets such as delta-like ligand 3 (DLL3), trophoblast cell surface antigen 2 (Trop2), B7-H3 (CD276), gangliosides disialoganglioside GD2 (GD2) and ganglioside GM2 (GM2) have been found to be expressed in SCLC, which makes them prime targets for therapy development. While investigated therapies such as rovalpituzumab tesirine (Rova-T) have failed, several insights from these trials have led to the development of compelling new agents such as sacituzumab govitecan (SG), ifinatamab deruxtecan (I-DXd), tarlatamab, and DLL3-targeted CAR-T cells. Advancing development of molecular testing and improving targeted approaches remain integral to pushing forward the progress of adoptive cell therapies in SCLC.

Preclinical evaluation of a novel antibody-drug conjugate OBI-992 for Cancer therapy

Trophoblast cell surface antigen 2 (TROP2), a transmembrane glycoprotein highly expressed in a variety of epithelial cancers, has been considered as a primary therapeutic target for the development of antibody-drug conjugates (ADCs). OBI-992, an investigational TROP2-targeted ADC, is composed of a novel TROP2 antibody (R4702) conjugated to the topoisomerase I (TOP1) inhibitor exatecan through a hydrophilic enzyme-cleavable linker. This study aimed to characterize R4702 and OBI-992 in vitro. TROP2-targeted antibodies sacituzumab and datopotamab were employed as the comparators for R4702. ADCs sacituzumab govitecan (SG) and datopotamab deruxtecan (Dato-DXd) were used as benchmarks for OBI-992. Results revealed that R4702 binds to an epitope that is distinct from sacituzumab and datopotamab. The cytotoxicity of the OBI-992, SG, and Dato-DXd against different cancer cells is comparable despite they have different internalization profile. Upregulation of breast cancer resistance protein (BCRP) was observed in SG-resistant and Dato-DXd-resistant cells, but not in OBI-992-resistant cells. In addition, significant downregulation of TROP2 expression was detected with Dato-DXd-resistant cells and only slightly downregulation with SG- and OBI-992-resistant cells was observed. Moreover, substantial enhancement of cytotoxicity and DNA damage was found in the combination of OBI-992 with a poly (ADP-ribose) polymerase (PARP) inhibitor (talazoparib). Taken together, the findings in this study support further clinical development of OBI-992.

Mechanisms of antigen-dependent resistance to chimeric antigen receptor (CAR)-T cell therapies

Cancer immunotherapy has reshaped the landscape of cancer treatment over the past decades. Genetic manipulation of T cells to express synthetic receptors, known as chimeric antigen receptors (CAR), has led to the creation of tremendous commercial and therapeutic success for the treatment of certain hematologic malignancies. However, since the engagement of CAR-T cells with their respective antigens is solely what triggers their cytotoxic reactions against target cells, the slightest changes to the availability and/or structure of the target antigen often result in the incapacitation of CAR-T cells to enforce tumoricidal responses. This results in the resistance of tumor cells to a particular CAR-T cell therapy that requires meticulous heeding to sustain remissions in cancer patients. In this review, we highlight the antigen-dependent resistance mechanisms by which tumor cells dodge being recognized and targeted by CAR-T cells. Moreover, since substituting the target antigen is the most potent strategy for overcoming antigen-dependent disease relapse, we tend to highlight the current status of some target antigens that might be considered suitable alternatives to the currently available antigens in various cancers. We also propose target antigens whose targeting might reduce the off-tumor adverse events of CAR-T cells in certain malignancies.

Drug Treatment Direction Based on the Molecular Mechanism of Breast Cancer Brain Metastasis

Today, breast cancer (BC) is the most frequently diagnosed malignancy and a leading cause of cancer-related deaths among women worldwide. Brain metastases (BMs) are a common complication among individuals with advanced breast cancer, significantly impacting both survival rates and the overall condition of life of patients. This review systematically analyzes the innovative approaches to drug treatment for breast cancer brain metastases (BCBMs), with particular emphasis placed on treatments targeting molecular mechanisms and signaling pathways and drug delivery strategies targeting the blood brain barrier (BBB). The article discusses various drugs that have demonstrated effectiveness against BCBM, featuring a mix of monoclonal antibodies, nimble small-molecule tyrosine kinase inhibitors (TKIs), and innovative antibody-drug conjugates (ADCs). This study of various drugs and techniques designed to boost the permeability of the BBB sheds light on how these innovations can improve the treatment of brain metastases. This review highlights the need to develop new therapies for BCBM and to optimize existing treatment strategies. With a deeper comprehension of the intricate molecular mechanisms and advances in drug delivery technology, it is expected that more effective personalized treatment options will become available in the future for patients with BCBM.

Five-Gene Expression Signature Associated With Acquired FOLFIRI Resistance and Survival in Metastatic Colorectal Cancer

FOLFIRI, a combination of folinic acid, 5-fluorouracil, and irinotecan, is one of the recommended first-line chemotherapeutic treatments for metastatic colorectal cancer. Unfortunately, acquired FOLFIRI resistance represents a common obstacle in the treatment of metastatic colorectal cancer patients. Thus, we aimed to identify mechanisms, gene alterations, and gene expression signatures contributing to acquired FOLFIRI resistance by mimicking this problem in a cell culture model and subsequent translation in clinical data sets. Three FOLFIRI-resistant colorectal cancer (CRC) cell lines were established by continuous FOLFIRI treatment. Comparative mutation screening (161 genes) and transcriptomics (pathway and differential expression analyses) were performed in parental and resistant cells. Data reconciliation was performed in GSE62322, a clinical FOLFIRI responder data set (intrinsic resistance). Relapse-free survival (RFS) associations of identified differentially expressed genes and potential gene signatures were investigated in 8 clinical CRC data sets. No mutual genetic alterations were found in FOLFIRI-resistant derivatives. Resistant cell lines displayed activation of mitogen-activated protein kinase, immune response, and epithelial-mesenchymal transition pathways. Twelve differentially expressed genes, significantly differentially expressed in at least 2 of the 3 resistant cell lines, were identified. Comparison with GSE62322 and subsequent survival analyses revealed a 5-gene FOLFIRI signature comprised of CAV2, TNC, TACSTD2, SERPINE2, and PERP that was associated with RFS in multiple data sets including the cancer genome atlas CRC (hazard ratio [HR] =2.634, P = 4.53 × 10-6), in pooled samples of all data sets (all stages [N = 1981]: HR = 1.852, P = 6.44 × 10-13; stage IV [N = 260]: HR = 2.462, P = 5.22 × 10-9). A multivariate Cox regression analysis identified the 5-gene signature as an independent prognostic factor in the cancer genome atlas data set (HR = 1.89, P = .0202). Our analyses revealed a 5-gene FOLFIRI resistance signature associated with RFS that may help predict FOLFIRI resistance and thus avoid unnecessary ineffective treatment. Signature members might also represent targets to fight FOLFIRI resistance.

Distinct gene signatures define the epithelial cell features of mucinous appendiceal neoplasms and pseudomyxoma metastases

Introduction

Appendiceal mucinous neoplasms (AMN) are rare tumors of the gastrointestinal tract. They metastasize with widespread abdominal dissemination leading to pseudomyxoma peritonei (PMP), a disease with poor prognosis. There are many unknowns about the cellular features of origin, differentiation and progression of AMN and PMP.

Methods

We characterized AMNs, PMPs and matched normal tissues using single-cell RNA-sequencing. We validated our findings with immunohistochemistry, mass spectrometry on malignant ascites from PMP patients and gene expression data from an independent set of PMP tumors.

Results

We identified previously undescribed cellular features and heterogeneity in AMN and PMP tumors. There were gene expression signatures specific to the tumor epithelial cells among AMN and PMP. These signatures included genes indicative of goblet cell differentiation and elevated mucin gene expression. Metastatic PMP cells had a distinct gene expression signature with increased lipid metabolism, inflammatory, JAK-STAT and RAS signaling pathway among others. We observed clonal heterogeneity in a single PMP tumor as well as PMP metastases from the same patient.

Discussion

Our study defined tumor cell gene signatures of AMN and PMP, successfully overcoming challenges of low cellularity and mucinous composition of these tumors. These gene expression signatures provide insights on tumor origin and differentiation, together with the identification of novel treatment targets. The heterogeneity observed within an individual tumor and between different tumors from the same patient, represents a potential source of treatment resistance.

OBI-992, a Novel TROP2-Targeted Antibody-Drug Conjugate, Demonstrates Antitumor Activity in Multiple Cancer Models

Trophoblast cell surface antigen 2 (TROP2) is highly expressed in multiple cancers relative to normal tissues, supporting its role as a target for cancer therapy. OBI-992 is an antibody-drug conjugate (ADC) derived from a novel TROP2-targeted antibody linked to the topoisomerase 1 (TOP1) inhibitor exatecan via an enzyme-cleavable hydrophilic linker, with a drug-antibody ratio of 4. This study evaluated and compared the antitumor activity of OBI-992 with that of benchmark TROP2-targeted ADCs datopotamab deruxtecan (Dato-DXd) and sacituzumab govitecan (SG) in cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) models. OBI-992 treatment exhibited statistically significant antitumor activity versus controls at doses of 3 and 10 mg/kg in various CDX and PDX models, demonstrating comparable or better antitumor activity with benchmark ADCs. In a large-tumor model, longer survival times were observed in OBI-992-treated mice compared with Dato-DXd-treated mice. OBI-992 treatment induced marked bystander killing of TROP2-negative cells in the presence of nearby TROP2-positive cells in both in vitro and in vivo studies. In lung adenocarcinoma CDX models with overexpression of either P-glycoprotein (P-gp) or breast cancer resistance protein (BCRP) to mimic ATP-binding cassette transporter-mediated multidrug resistance, OBI-992 treatment maintained antitumor activity when Dato-DXd treatment became less effective. The combination of OBI-992 at suboptimal doses with either poly (ADP-ribose) polymerase (PARP) inhibitors or an immune check point inhibitor produced synergistic antitumor effects in mouse models. Taken together, these translational results support further development of OBI-992 as a cancer therapy.

Combination strategies with PARP inhibitors in BRCA-mutated triple-negative breast cancer: overcoming resistance mechanisms

Triple-negative breast cancer (TNBC) is a particularly aggressive breast cancer subtype, characterised by a higher incidence in younger women, rapid metastasis, and a generally poor prognosis. Patients with TNBC and BRCA mutations face additional therapeutic challenges due to the cancer's intrinsic resistance to conventional therapies. Poly (ADP-ribose) polymerase inhibitors (PARPis) have emerged as a promising targeted treatment for BRCA-mutated TNBC, exploiting vulnerabilities in the homologous recombination repair (HRR) pathway. However, despite initial success, the efficacy of PARPis is often compromised by the development of resistance mechanisms, including HRR restoration, stabilisation of replication forks, reduced PARP1 trapping, and drug efflux. This review explores latest breakthroughs in overcoming PARPi resistance through combination therapies. These strategies include the integration of PARPis with chemotherapy, immunotherapy, antibody-drug conjugates, and PI3K/AKT pathway inhibitors. These combinations aim to enhance the therapeutic efficacy of PARPis by targeting multiple cancer progression pathways. The review also discusses the evolving role of PARPis within the broader treatment paradigm for BRCA-mutated TNBC, emphasising the need for ongoing research and clinical trials to optimise combination strategies. By tackling the challenges associated with PARPi resistance and exploring novel combination therapies, this review sheds light on the future possibilities for improving outcomes for patients with BRCA-mutated TNBC.

Emerging Targeted Therapies in Non-Small-Cell Lung Cancer (NSCLC)

Targeted therapies have changed the treatment landscape of non-small-cell lung cancer and led to improved patient survival across all stages of lung cancer. Newer advances in common and novel oncogenic drivers continue to occur at vigorous speed, making it challenging to stay up to date with the rapidly evolving field. In this article, we review the emerging perspectives in the treatment of actionable targets in lung cancer. We focus on the development of newer KRAS-directed therapies, particularly on non-G12C mutations, pan-RAS inhibitors, and RAS-GTP inhibitors. We also describe the current standard of care for EGFR- and ALK-altered NSCLC and dive into the novel treatments expected to be in the clinic soon. A similar approach is taken toward MET, HER2, RET, ROS1, and FGFR alterations as emerging targets in non-small-cell lung cancer. Finally, we conclude this review with the current body of evidence for targeting TROP-2 as a novel target, potentially of importance in post-targeted therapy scenarios.

Advances in antibody-drug conjugates in the treatment of advanced triple-negative breast cancer: a narrative review

Background and Objective

Triple-negative breast cancer (TNBC) is more aggressive when compared with other breast cancer subtypes, and advanced TNBC (aTNBC) has always been a challenge for clinical treatment. In recent years, significant progress has been made in the research of antibody-drug conjugates (ADCs), especially targeting trophoblast cell-surface antigen 2 (TROP2), as an effective regimen to enhance the potential survival benefit and quality of life of relevant patients. The objective of this narrative review is to provide a comprehensive knowledge on latest progress of ADCs in the treatment of aTNBC. Furthermore, the clinical significance and future research directions for ADCs are also discussed.

Methods

As of December 2023, literature spanning the past decade was comprehensively searched and analyzed across PubMed, Wanfang Data, ClinicalTrials.gov, and relevant academic conferences, to identify the latest published literature or ongoing trials on ADCs for aTNBC. The selected literature primarily focused on the drug structural profile, pharmacological mechanism, important trials targeting different antigens, and other exploratory investigations.

Key Content and Findings

The advent of precision therapy has been facilitated by the new generation ADCs, which have demonstrated the capacity to prolong survival in patients with refractory aTNBC, and promote the research on molecular biological characteristics of aTNBC. Meanwhile, several clinical issues on treatment are emerging, including a detailed understanding of the clinical profile differences among specific ADCs, identification of the potential indications for ADCs, and management strategies for the adverse effects related to ADCs. Additionally, it is essential to clarify the clinical significance of the expression level of the target antigen for ADCs, to comprehend resistance mechanisms to ADCs, and to determine the optimal sequence of treatments between different ADCs. Furthermore, there is a need to investigate the potential of combination immunotherapy with ADCs. Up to date, the preliminary investigations on the aforementioned issues have been initiated, and further research will facilitate the enhancement of ADCs clinical utilization.

Conclusions

The use of ADCs has been recommended by various clinical guidelines, and significantly altering the landscape of treatment for aTNBC. Nevertheless, further investigation are required to determine the most effective use of ADCs.

Datopotamab Deruxtecan Versus Chemotherapy in Previously Treated Inoperable/Metastatic Hormone Receptor-Positive Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer: Primary Results From TROPION-Breast01

PURPOSE

The global, phase 3, open-label, randomized TROPION-Breast01 study assessed the trophoblast cell surface antigen 2-directed antibody-drug conjugate datopotamab deruxtecan (Dato-DXd) versus investigator's choice of chemotherapy (ICC) in hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer.

METHODS

Adult patients with inoperable/metastatic HR+/HER2‒ breast cancer, who had disease progression on endocrine therapy, for whom endocrine therapy was unsuitable, and had received one to two previous lines of chemotherapy in the inoperable/metastatic setting, were randomly assigned 1:1 to Dato-DXd (6 mg/kg once every 3 weeks) or ICC (eribulin/vinorelbine/capecitabine/gemcitabine). Dual primary end points were progression-free survival (PFS) by blinded independent central review (BICR) and overall survival (OS).

RESULTS

Patients were randomly assigned to Dato-DXd (n = 365) or ICC (n = 367). Dato-DXd significantly reduced the risk of progression or death versus ICC (PFS by BICR hazard ratio [HR], 0.63 [95% CI, 0.52 to 0.76]; P < .0001). Consistent PFS benefit was observed across subgroups. Although OS data were not mature, a trend favoring Dato-DXd was observed (HR, 0.84 [95% CI, 0.62 to 1.14]). The rate of grade ≥3 treatment-related adverse events (TRAEs) with Dato-DXd was lower than ICC (20.8% v 44.7%). The most common TRAEs (any grade; grade ≥3) were nausea (51.1%; 1.4%) and stomatitis (50%; 6.4%) with Dato-DXd and neutropenia (grouped term, 42.5%; 30.8%) with ICC.

CONCLUSION

Patients receiving Dato-DXd had statistically significant and clinically meaningful improvement in PFS and a favorable and manageable safety profile, compared with ICC. Results support Dato-DXd as a novel treatment option for patients with inoperable/metastatic HR+/HER2‒ breast cancer who have received one to two previous lines of chemotherapy in this setting.

Exploring the Prognostic Role of Trop-2, CD47, and CD163 Expression Levels on Survival Outcomes in Patients with Triple-Negative Breast Cancer

Background: This study evaluated the prognostic impact of Trop-2, CD47, and CD163 expression on clinical outcomes in triple-negative breast cancer (TNBC) and investigated their interactions with tumor progression. Methods: A retrospective cohort of 92 patients with TNBC was analyzed. The expression scores for Trop-2, CD47, and CD163 were categorized as negative/low (0-3 points) or high (4-6 points). The primary endpoint was overall survival (OS). Results: The median age of the cohort was 50 years old. High Trop-2 expression was observed in 55.4% of the patients and was significantly associated with advanced disease stage (p < 0.001). High CD47 expression (44.6%) was correlated with advanced stage (p = 0.044), whereas high CD163 expression (45.7%) was associated with advanced stage (p = 0.021), absence of comorbidities (p = 0.022), and lower pT stage (p = 0.023). Moderate positive correlations were found between Trop-2 and CD47 (p = 0.022), Trop-2 and CD163 (p = 0.037), and CD47 and CD163 (p < 0.001), respectively. Kaplan-Meier survival analysis revealed that patients with low Trop-2 expression exhibited significantly prolonged OS (p = 0.021) and progression-free survival (PFS) (p = 0.026) compared to those with high Trop-2 expression. Univariate and multivariate analyses revealed significant associations between OS and PFS for Trop-2, lymphovascular invasion, and BRCA status. Conclusions: Trop-2 expression is a significant prognostic factor for TNBC and is correlated with worse outcomes. Although CD47 and CD163 showed trends for poorer prognosis, their significance was not confirmed. These findings offer promising prospects for future studies on combined antibody-drug conjugates (ADCs), as they may present opportunities to address multiple resistance mechanisms in the management of TNBC and enhance clinical outcomes.

Phase 2 Open-Label Study of Sacituzumab Govitecan as Second-Line Therapy in Patients With Extensive-Stage SCLC: Results From TROPiCS-03

INTRODUCTION

The phase 2 TROPiCS-03 study evaluated the efficacy/safety of sacituzumab govitecan (SG) as second-line treatment in patients with previously treated extensive-stage SCLC (ES-SCLC).

METHODS

TROPiCS-03 (NCT03964727) is a multicohort, open-label, phase 2 basket study of solid tumors, including ES-SCLC. Adults with ES-SCLC that progressed after one previous line of platinum-based chemotherapy and anti-programmed death-(ligand) 1 (PD-[L]1) therapy received SG 10 mg/kg on days 1 and 8 of a 21-day cycle. The primary end point was the investigator-assessed objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors version 1.1. Key secondary end points included investigator-assessed duration of response (DOR) and progression-free survival (PFS); blinded independent central review-assessed ORR, DOR, and PFS; overall survival (OS); and safety. Efficacy was evaluated in patients with platinum-resistant and platinum-sensitive disease.

RESULTS

Among 43 patients (median follow-up, 12.3 [range, 8.1-20.1] mo), investigator-assessed ORR was 41.9% (95% confidence interval [CI]: 27.0%-57.9%), with 18 confirmed partial responses; median (95% CI) DOR, PFS, and OS were 4.73 (3.52-6.70), 4.40 (3.81-6.11), and 13.60 (6.57-14.78) months, respectively. The efficacy results of the blinded independent central review assessments were similar. The investigator-assessed ORR (95% CI) was 35.0% (15.4%-59.2%) in patients with platinum-resistant disease (n = 20) and 47.8% (26.8%-69.4%) in patients with platinum-sensitive disease (n = 23). Furthermore, 32 patients (74.4%) had grade greater than or equal to 3 treatment-emergent adverse events (TEAEs). No TEAE led to SG discontinuation; one treatment-related TEAE (neutropenic sepsis) led to death.

CONCLUSIONS

SG has promising efficacy as second-line treatment of ES-SCLC, irrespective of platinum sensitivity. Safety was manageable and consistent with that observed in other SG studies.

Evaluation of Methylation and Changes in the Transcriptomics and Proteomics of the GRHL3, PHLDA3, and in Patients with Head and Neck Squamous Cell Carcinoma

Introduction

Head and Neck Squamous Cell Carcinoma (HNSCC) is the sixth most common malignancy in the world. High mortality and severe complications are critical features of head and neck cancer. Changes in intracellular signaling pathways are a general tumor formation and progression mechanism. Due to the objectivity that the PI3K pathway plays a critical role in HNSCC. the negative regulators involved in this pathway such as GRHL3, PHLDA3, which have been reported to reduce their expression in malignancies, can achieve significant results in the detection, prognosis, and targeted treatment of HNSCC if changes in transcriptome, proteome, and methylation levels of these genes are observed.

Method

45 fresh head and neck cancer cells and 45 control samples were collected. Protein expression was also studied using Western blot. Additionally, promoter methylation was investigated using the qMSP method to observe changes in the regulatory regions.

Results

The results indicate a significant decrease in GRHL3 expression and a significant increase in PHLDA3 expression. Notably, these expression changes were not confirmed at the protein level. Additionally, methylation analysis revealed hypermethylation of the promoter region in GRHL3 and hypomethylation in PHLDA3.

Conclusion

This study is the first to examine the genes GRHL3 and PHLDA3 at the transcriptome, proteome, and promoter methylation levels. Based on the results, we hope that further studies will confirm the potential of GRHL3 and PHLDA3 as prognostic biomarkers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-024-05057-0.

Targeted Therapy in Salivary Gland Cancer: Prevalence of a Selected Panel of Actionable Molecular Alterations in a German Tertiary Referral Center Patient Cohort

OBJECTIVE

Salivary gland carcinomas (SGC) are a heterogeneous group of malignancies, with 24 subtypes defined by the World Health Organization (WHO). The standard of therapy is surgical resection, with adjuvant radiotherapy in most cases. However, disease recurrence (R) or metastasis (M) is common and no active systemic therapies are currently available for RM-SGC resulting in a 5-year survival rate of only 20%.

PATIENTS AND METHODS

Overall, 55 SGC patients with seven different histological tumor subtypes were included in this study. formalin-fixed paraffin-embedded (FFPE) tissue samples were used for immunohistochemical (IHC) staining targeting HER2/neu, androgen receptor (AR), PD-L1, EGFR, panTRK, and TROP2. Fluorescence in situ hybridization (FISH) was performed for detecting HER2/neu amplifications and NTRK1/2/3 translocations in selected cases with relevant HER2/neu and panTRK protein expression, respectively. IHC and FISH results were correlated with patients' clinical and histopathological data.

RESULTS

The overall prevalence of druggable molecular alterations, defined as an immunoreactive score ≥ 9 in at least one of the analyzed targets, was 54.4% with the highest percentage in oncocytic carcinomas (100%) and lowest percentage in acinic cell carcinomas (10%). EGFR overexpression proved to be the most common alteration (32.7% of cases) followed by overexpression of TROP2 (27.3%), AR (10.9%), HER2/neu (7.3%), PD-L1 (1.8%), and panTRK (1.8%). HER2/neu amplifications were found in 50% and NTRK translocations were found in 100% of all cases with elevated Her2/neu and panTRK protein expression, respectively.

CONCLUSIONS

Our data indicate that targeted therapy using e.g., trastuzumab deruxtecan, bicalutamide, pembrolizumab, cetuximab, entrectinib or sacituzumab govitecan might be a promising option especially for a relevant subset of patients with RM-SGC not suitable for salvage surgery. However, evidence from clinical studies regarding response rates to these therapies remains sparse, which underlines the need of multicenter clinical trials.

Targeting Refractory Triple-Negative Breast Cancer with Sacituzumab Govitecan: A New Era in Precision Medicine

Advanced triple-negative breast cancer (TNBC) has poorer outcomes due to its aggressive behavior and restricted therapeutic options. While therapies like checkpoint inhibitors and PARP inhibitors offer some benefits, chemotherapy remains ineffective beyond the first line of treatment. Antibody-drug conjugates (ADCs) like sacituzumab govitecan-hziy (SG) represent a significant advancement. SG combines SN-38, an irinotecan derivative, with a Trop-2-targeting antibody via a pH-sensitive linking moiety, achieving a good drug:antibody ratio. In a phase I-II study involving metastatic TNBC (mTNBC) individuals, SG achieved an overall response rate of 33.3% and a median response period of 7.7 months. The phase III ASCENT trial demonstrated SG's efficacy in relapsed or refractory TNBC, improving median progression-free survival and median overall survival compared to chemotherapy. Common side effects include neutropenia, nausea, and fatigue. This article highlights the clinical potential, pharmacokinetics, safety profile, and resistance mechanisms of SG along with key ongoing clinical trials, emphasizing its role in managing refractory mTNBC, especially in third-line therapy. The review also discusses current strategies for managing adverse reactions and sequencing ADC treatments in clinical practice, along with the predicted basis of resistance. The optimal sequencing of SG relative to other ADCs, such as trastuzumab deruxtecan or T-DXd, remains an evolving question, especially as newer agents with distinct mechanisms of action and safety profiles enter the field. Further research is essential to establish evidence-based strategies for sequencing SG and addressing disease progression post-ADC therapy.

The Role of Antibody-Drug Conjugates in Urothelial Cancer: A Review of Recent Advances in the Treatment of Locally Advanced and Metastatic Urothelial Cancer

Locally advanced and metastatic urothelial cancer (la/mUC) is an aggressive disease with poor prognosis. Platinum-based chemotherapy has remained the first-line treatment for decades and until recently no other treatment options existed. Today, novel agents called antibody drug conjugates (ADCs), including enfortumab vedotin (EV) and sacituzumab govitecan (SG), have been approved for la/mUC offering patients treatment options following or instead of traditional chemotherapy. The EV consists of the chemotherapy monomethyl auristatin E linked to anti-nectin-4 antibody. Single-agent response rates for EV are 40% to 52% including activity in patients with liver metastases, a phenotype associated with worse outcomes. In 2023, EV in combination with pembrolizumab almost doubled progression-free and overall survival versus platinum-based chemotherapy, which led to accelerated FDA approval as first-line treatment for all patients with la/mUC. Safety profile of EV monotherapy and combination with pembrolizumab is generally manageable with peripheral neuropathy and cutaneous toxicity among the most common treatment-related adverse events (TRAEs). The SG is another ADC targeting TROP-2 with SN-38 as payload. It is approved as late-line treatment for la/mUC with ORR 27% and most common TRAEs include gastrointestinal symptoms and neutropenia. Finally, a recent cancer agnostic accelerated approval for trastuzumab deruxtecan (T-DXd) in HER2-positive (IHC3+) solid tumors provides another active ADC option for biomarker-selected patients with treatment refractory la/mUC. Several new ADCs are being investigated in urothelial cancer (UC) clinical trials. This review summarizes the clinical studies and real-world data regarding the use of ADCs in UC.

Programming tissue-sensing T cells that deliver therapies to the brain

To engineer cells that can specifically target the central nervous system (CNS), we identified extracellular CNS-specific antigens, including components of the CNS extracellular matrix and surface molecules expressed on neurons or glial cells. Synthetic Notch receptors engineered to detect these antigens were used to program T cells to induce the expression of diverse payloads only in the brain. CNS-targeted T cells that induced chimeric antigen receptor expression efficiently cleared primary and secondary brain tumors without harming cross-reactive cells outside of the brain. Conversely, CNS-targeted cells that locally delivered the immunosuppressive cytokine interleukin-10 ameliorated symptoms in a mouse model of neuroinflammation. Tissue-sensing cells represent a strategy for addressing diverse disorders in an anatomically targeted manner.

Trop2-Targeted Molecular Imaging in Solid Tumors: Current Advances and Future Outlook

Trophoblast cell surface antigen 2 (Trop2), a transmembrane glycoprotein, plays a dual role in physiological and pathological processes. In healthy tissues, Trop2 facilitates development and orchestrates intracellular calcium signaling. However, its overexpression in numerous solid tumors shifts its function toward driving cell proliferation and metastasis, thus leading to a poor prognosis. The clinical relevance of Trop2 is underscored by its utility as both a biomarker for diagnostic imaging and a target for therapy. Notably, the U.S. Food and Drug Administration (FDA) has approved sacituzumab govitecan (SG), a novel Trop2-targeted agent, for treating triple-negative breast cancer (TNBC) and refractory urothelial cancer, highlighting the significance of Trop2 in clinical oncology. Molecular imaging, a powerful tool for visualizing and quantifying biological phenomena at the molecular and cellular levels, has emerged as a critical technique for studying Trop2. This approach encompasses various modalities, including optical imaging, positron emission tomography (PET), single photon emission computed tomography (SPECT), and targeted antibodies labeled with radioactive isotopes. Incorporating Trop2-targeted molecular imaging into clinical practice is vital for the early detection, prognostic assessment, and treatment planning of a broad spectrum of solid tumors. Our review captures the latest progress in Trop2-targeted molecular imaging, focusing on both diagnostic and therapeutic applications across diverse tumor types, including lung, breast, gastric, pancreatic, prostate, and cervical cancers, as well as salivary gland carcinomas. We critically evaluate the current state by examining the relevant applications, diagnostic accuracy, therapeutic efficacy, and inherent limitations. Finally, we analyze the challenges impeding widespread clinical application and offer insights into strategies for advancing the field, thereby guiding future research endeavors.

Precision medicine for urothelial carcinoma: An international perspective

The treatment landscape of urothelial cancers has evolved in the last decade with the approval of chemotherapy, immune checkpoint inhibitors, targeted therapies, and antibody drug conjugates. Although improvements in response and survival have been achieved with these strategies, in some scenarios their benefit is still questionable. Current efforts to identify prognostic and predictive biomarkers are crucial for better patient selection and treatment outcomes. In this paper we will review the most promising biomarkers under investigation, such as molecular classifiers, genomic alterations, programmed cell death ligand 1 expression, tumor mutational burden, circulating tumor DNA, urinary biomarkers among others, for muscle invasive bladder cancer and metastatic urothelial cancers. Deeper understanding of these biomarkers will aid clinical decision-making and help tailor treatment strategies.

Immuno-PET/CT Imaging of Trop2 with [18F]AlF-RESCA-T4 Differentiates Lung Cancer from Inflammation

Immuno-PET/CT imaging, a branch of molecular imaging, can noninvasively and specifically visualize biomarker expression across the body. Trophoblast cell surface antigen 2 (Trop2) is a pan-cancer biomarker and plays a crucial role in tumorigenesis through multiple signaling pathways. The study aims to develop and translate novel Trop2 single-domain antibody (sdAb) tracers for clinical use. Methods: Two sdAbs (i.e., His-tagged T4 and His-tag-free RT4) are recombinantly expressed in Chinese hamster ovary cells. The purities and binding kinetics are determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, high-performance liquid chromatography, and surface plasmon resonance assays. The AlF restrained complexing agent (RESCA) method is applied to develop 18F-labeled sdAb tracers ([18F]AlF-RESCA-T4 and [18F]AlF-RESCA-RT4), followed by thorough preclinical imaging and blocking studies on tumor-bearing mice and a pilot clinical trial evaluating the clinical imaging safety and feasibility of [18F]AlF-RESCA-T4 immuno-PET/CT. Results: [18F]AlF-RESCA-T4 and [18F]AlF-RESCA-RT4 possess high radiochemical purities. Preclinical imaging in the T3M-4 tumor model revealed prominent uptake (percentage injected dose/g) of [18F]AlF-RESCA-T4 (11.13 ± 1.53, n = 4) and [18F]AlF-RESCA-RT4 (8.83 ± 1.22, n = 4), which were significantly reduced by coinjection of unlabeled T4 and RT4 in blocking studies. The His-tag removal strategy further optimized the probe's in vivo pharmacokinetics and reduced renal radioactivity accumulation without significantly decreasing tumor uptake. In a pilot clinical trial, [18F]AlF-RESCA-T4 immuno-PET/CT showed promising potency in annotating Trop2 expression and differentiating tumors from inflammatory diseases such as tuberculosis. Conclusion: [18F]AlF-RESCA-T4 and [18F]AlF-RESCA-RT4 can specifically annotate Trop2 expression. Clinical [18F]AlF-RESCA-T4 immuno-PET/CT imaging can screen patients for Trop2-targeted therapies and differentiate lung inflammation from cancer.

Efficacy and safety of sacituzumab govitecan Trop-2-targeted antibody-drug conjugate in solid tumors and UGT1A1*28 polymorphism: a systematic review and meta-analysis

BACKGROUND

Sacituzumab govitecan (SG) is a promising Trop-2-targeted antibody-drug conjugate (ADC) approved for the treatment of metastatic triple-negative breast cancer (TNBC). Early phase clinical trials have demonstrated good clinical activity and safety profile of SG in various tumor types, albeit with differing response rates and durations. The aim of this systematic review and meta-analysis was to evaluate the clinical efficacy and toxicity of SG and the influence of UGT1A1*28 genotype in clinical trials involving solid tumors.

METHODS

A systematic review of the literature from publicly available databases was performed on February 15, 2024 whereby studies published till 15 February 2024 were retrieved according to PRISMA guidelines [PROSPERO #CRD42022359943]. Data extracted included tumor type, sample size, demographic information, SG dose, UGT1A1*28 status, toxicity events, duration of follow-up, response, and survival outcomes. Risks of bias analysis was refereed using the Joanna Briggs Institute quality assessment tool for the cohort and RCT studies using 11 and 13 parameters, respectively. Statistical analysis was performed using the DerSimonian and Laird inverse variance methods. Heterogeneity was assessed using the I2 statistic and Χ2 tests. P value < 0.05 was considered as statistical significance.

RESULTS

Eleven eligible clinical trials comprised of 1578 patients harboring various tumor types including TNBC, lung, genitourinary and gastrointestinal malignancies were included in the systematic review and meta-analysis. Pooled incidences of severe adverse events were minimal at <10%, with the exception of grade 3-4 neutropenia at 37.4%. The median PFS and OS across all studies were 4.9 (95%CI: 4.0-5.8) months and 9.6 (95%CI: 7.6-11.6) months, respectively. Objective response rate across all studies evaluated was 17.1% (95%CI: 12.0-22.1).

CONCLUSION

Our systematic review and meta-analysis confirmed that SG confers good clinical activity in certain solid tumor types and was tolerable with minimal adverse events. The potential utility of UGT1A1*28 genotyping in predicting clinical response and outcomes could not be determined due to the limited number of studies with available UGT1A1 genotype data.

Current Status and Future Prospects of TROP-2 ADCs in Lung Cancer Treatment

Lung cancer is the leading cause of mortality worldwide, and non-small cell lung cancer accounts for the majority of lung cancer cases. Chemotherapy and radiotherapy constitute the mainstays of lung cancer treatment; however, their associated side effects involving the kidneys, nervous system, gastrointestinal tract, and liver further add to dismal outcomes. The advent of antibody‒drug conjugates (ADCs) could change this situation. Trophoblast surface antigen 2 (TROP-2), a human trophoblast surface antigen, is a tumor-associated antigen that is expressed at low levels in normal tissues and is overexpressed in a variety of malignant tumors. The differential expression of the TROP-2 protein in a variety of tumors makes tumor immunotherapy with ADCs targeting TROP-2 a promising approach. Previous studies have shown that the expression of TROP-2 is related to the prognosis of patients with lung cancer and that TROP-2 expression is different across different histological types; however, research on TROP-2 and TROP-2 ADCs in patients with lung cancer is not comprehensive. The aims of this study were to review the mechanism of action and clinical efficacy of TROP-2 and related drugs in the treatment of lung cancer, to elucidate the prognostic value of TROP-2 in lung cancer, and to discuss the future prospects of TROP-2 ADCs to provide a reference for the precise treatment of lung cancer.

A novel shark VNAR antibody-based immunotoxin targeting TROP-2 for cancer therapy

TROP-2, a tumor-associated antigen, has been implicated in the progression of various epithelial tumors. Due to its favorable expression profile, TROP-2 has emerged as a promising target for antibody-drug conjugates (ADCs) based anti-tumor therapies. Although ADCs have shown efficacy in cancer treatment, their application in solid tumors is hindered by their high molecular weight, poor tumor penetration, and release of cytotoxic molecules. Therefore, a recombinant immunotoxin was developed based on a shark-derived variable domain of immunoglobulin new antigen receptor (VNAR) antibody. VNARs are only one-tenth the size of IgG antibodies and possess remarkable tissue penetration capabilities and high stability. In this study, a shark VNAR phage display library was created, leading to the identification of shark VNAR-5G8 that targets TROP-2. VNAR-5G8 exhibited a high affinity and cellular internalization ability towards cells expressing high levels of TROP-2. Epitope analysis revealed that VNAR-5G8 recognizes a hidden epitope consisting of CRD and TY-1 on TROP-2. Subsequently, VNAR-5G8 was fused with a truncated form of Pseudomonas exotoxin (PE38) to create the recombinant immunotoxin (5G8-PE38), which exhibited significant anti-tumor activity in vitro and in vivo. Overall, this study highlights the promise of 5G8-PE38 as a valuable candidate for cancer therapy.

Advances in Trop-2 targeted antibody-drug conjugates for breast cancer: mechanisms, clinical applications, and future directions

Breast cancer remains a leading cause of cancer-related deaths among women worldwide, highlighting the need for novel therapeutic strategies. Trophoblast cell surface antigen 2 (Trop-2), a type I transmembrane glycoprotein highly expressed in various solid tumors including all subtypes of breast cancer, has emerged as a promising target for cancer therapy. This review focuses on recent advancements in Trop-2-targeted antibody-drug conjugates (ADCs) for breast cancer treatment. We comprehensively analyzed the structure and mechanism of action of ADCs, as well as the role of Trop-2 in breast cancer progression and prognosis. Several Trop-2-targeted ADCs, such as Sacituzumab Govitecan (SG) and Datopotamab Deruxtecan (Dato-DXd), have demonstrated significant antitumor activity in clinical trials for both triple-negative breast cancer (TNBC) and hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer. We systematically reviewed the ongoing clinical studies of these ADCs, highlighting their efficacy and safety profiles. Furthermore, we explored the potential of combining Trop-2-targeted ADCs with other therapeutic modalities, including immunotherapy, targeted therapies, and small molecule inhibitors. Notably, Trop-2-targeted ADCs have shown promise in reprogramming the tumor microenvironment through multiple signaling pathways, potentially enhancing antitumor immunity. This review aims to provide new insights and research directions for the development of innovative breast cancer therapies, offering potential solutions to improve treatment outcomes and quality of life for breast cancer patients.

Antibody drug conjugates in recurrent or metastatic cervical cancer: a focus on tisotumab vedotin state of art

Cervical cancer (CC) is still characterized by a poor prognosis despite the progress made in its treatment in recent years. Although immunotherapy has improved outcomes for advanced/recurrent disease, there is a significant gap in addressing patients' needs when they progress after platinum and immunotherapy treatments. In this setting, traditional chemotherapy showed limited effectiveness. In this context, antibody-drug conjugates (ADCs) emerged as a promising tool within targeted cancer therapies. Tisotumab vedotin (TV), an ADC targeting tissue factor, represents the first ADC approved by the US Food and Drug Administration for the treatment of recurrent or metastatic CC with disease progression on or after chemotherapy. In phase I-III published trials, TV has already demonstrated an advantage in terms of objective response rate (17.8%-54.4%) and progression-free survival (3.1-6.9 months) in patients who progressed to the first-line standard therapy. Data concerning the addition of TV to platinum/pembrolizumab first-line chemotherapy are still under analysis and strongly expected. However, several questions are still unresolved: (1) the identification of the most suitable timing for ADCs administration in the treatment sequence of advanced/recurrent CC; (2) the evaluation of combination therapies as a tool to minimize the emergence of resistant clones and to enhance overall effectiveness; and (3) the assessment of tolerability and correct management of special toxicities (e.g. ocular and neurological adverse events). In the near future, an improvement in patient selection via biomarker-driven strategies should be crucial for optimizing both treatment benefits and maintaining an acceptable toxicity profile.

Phase 1a study of ESG401, a Trop2 antibody-drug conjugate, in patients with locally advanced/metastatic solid tumors

This phase 1a study assesses ESG401 in patients with heavily pretreated locally advanced or metastatic solid tumors, focusing on metastatic breast cancer. Forty patients are enrolled: three experience dose-limiting toxicities, establishing the maximum tolerated dose at 16 mg/kg on days 1, 8, and 15 of a 28-day cycle. The most common grade ≥3 treatment-related adverse events are neutropenia and leukopenia. Among 38 efficacy-evaluable patients, the objective response rate (ORR) is 34.2%, the disease control rate (DCR) is 65.8%, and the clinical benefit rate (CBR) is 50.0% (including stable disease for at least 6 months). The median progression-free survival is 5.1 months, and the median duration of response is 6.3 months. In patients receiving therapeutically relevant doses, the ORR, DCR, and CBR are 40.6%, 75.0%, and 56.3%, respectively. ESG401 demonstrates a favorable safety profile and promising antitumor activity in this heavily treated population. The trial is registered at ClinicalTrials.gov (NCT04892342).

TROP2 in colorectal carcinoma: associations with histopathology, molecular phenotype, and patient prognosis

Antibody-drug conjugates (ADCs) directed to trophoblast cell surface antigen 2 (TROP2) have gained approval as a therapeutic option for advanced triple-negative breast cancer, and TROP2 expression has been linked to unfavourable outcomes in various malignancies. In colorectal carcinoma (CRC), there is still a lack of comprehensive studies on its expression frequency and its prognostic implications in relation to the main clinicopathological parameters. We examined the expression of TROP2 in a large cohort of 1,052 CRC cases and correlated our findings with histopathological and molecular parameters, tumour stage, and patient outcomes. TROP2 was heterogeneously expressed in 214/1,052 CRCs (20.3%), with only a fraction of strongly positive tumours. TROP2 expression significantly correlated with an invasive histological phenotype (e.g. increased tumour budding/aggressive histopathological subtypes), advanced tumour stage, microsatellite stable tumours, and p53 alterations. While TROP2 expression was prognostic in univariable analyses of the overall cohort (e.g. for disease-free survival, p < 0.001), it exhibited distinct variations among important clinicopathological subgroups (e.g. right- versus left-sided CRC, microsatellite stable versus unstable CRC, Union for International Cancer Control [UICC] stages) and lost its significance in multivariable analyses that included stage and CRC histopathology. In summary, TROP2 is quite frequently expressed in CRC and associated with an aggressive histopathological phenotype and microsatellite stable tumours. Future clinical trials investigating anti-TROP2 ADCs should acknowledge the observed intratumoural heterogeneity, given that only a subset of TROP2-expressing CRC show strong positivity. The prognostic implications of TROP2 are complex and show substantial variations across crucial clinicopathological subgroups, thus indicating that TROP2 is a suboptimal parameter to predict patient prognosis.

Plasma extracellular vesicles proteomics in meningioma patients

Tumor derived Extracellular vesicles (EVs) in circulating system may contain tumor-specific markers, and EV detection in body fluids could become an important tool for early tumor diagnosis, prognosis assessment. Meningiomas are the most common benign intracranial tumors, few studies have revealed specific protein markers for meningiomas from patients' body fluids. In this study, using proximity labeling technology and non-tumor patient plasma as a control, we detected protein levels of EVs in plasma samples from meningioma patients before and after surgery. Through bioinformatics analysis, we discovered that the levels of EV count and protein count in meningioma patients were significantly higher than those in healthy controls, and were significantly decreased postoperatively. Among EV proteins in meningioma patients, the levels of MUC1, SIGLEC11, E-Cadherin, KIT, and TASCTD2 were found not only significantly elevated than those in healthy controls, but also significantly decreased after tumor resection. Moreover, using publicly available GEO databases, we verified that the mRNA level of MUC1, SIGLEC11, and CDH1 in meningiomas were significantly higher in comparison with normal dura mater tissues. Additionally, by analyzing human meningioma specimens collected in this study, we validated the protein levels of MUC1 and SIGLEC11 were significantly increased in WHO grade 2 meningiomas and were positively correlated with tumor proliferation levels. This study indicates that meningiomas secret EV proteins into circulating system, which may serve as specific markers for diagnosis, malignancy predicting and tumor recurrent assessment.

Antibody-drug conjugates in solid tumors: a new frontier

PURPOSE OF REVIEW

Antibody-drug conjugates (ADCs) are designed to carry cytotoxic payloads and deliver them to specific molecular targets within tumor cells. Several ADCs are already approved with many more in development across several disease types. In this review, we will provide an overview of the ADCs currently approved and those under investigation in solid tumors.

RECENT FINDINGS

Currently there are dozens of ADCs under clinical study evaluation of a variety of solid tumors, and preliminary results are promising. Multiple ADCs have received regulatory approval in disease such as breast cancer, non-small cell lung cancer, and bladder cancer. While some are approved in biomarker selected settings with disease specific indication (e.g. breast cancer), others have been approved irrespective of biomarker expression (urothelial carcinoma) and pan-cancer indications in biomarker selected patients (HER2 3+ expression).

SUMMARY

Cytotoxic chemotherapy has been the mainstay of systemic treatment for patients with various solid tumors. ADCs offer the advantage of carrying the cytotoxic payload onto a specific molecular receptor, thereby inducing a more selective response. Optimizing selection of target antigen, payload delivery and investigating biomarkers of response will be crucial for further expanding the therapeutic benefit of ADCs across solid tumors.

Sacituzumab govitecan in triple-negative breast cancer: from bench to bedside, and back

Triple-negative breast cancer (TNBC) represents a major therapeutic challenge due to its heterogeneous and aggressive phenotype, and limited target-specific treatment options. The trophoblast cell surface antigen (Trop-2), a transmembrane glycoprotein overexpressed in various cancers, has emerged as a promising target for TNBC. Sacituzumab govitecan (SG), an antibody-drug conjugate (ADC) that targets Trop-2, has recently entered treatment algorithms for advanced and metastatic TNBC, independently from Trop-2 expression status, with manageable toxicity. Despite the impressive results, questions remain unsolved regarding its efficacy, safety profile, and Trop-2 biological role in cancer. Currently, Trop-2 cannot be designated as a predictive biomarker in SG treatment, albeit its expression correlates with disease outcome, yet its levels are not uniform across all TNBCs. Additionally, data regarding Trop-2 expression variations in primary and metastatic sites, and its interplay with other biomarkers are still ambiguous but mandatory in light of future applications of SG in other indications and settings. This poses the questions of a careful evaluation of the efficacy and toxicity profile of SG in such early stages of disease, and in personalized and combinatorial strategies. Research and clinical data are mandatory to address SG drawbacks and minimize its benefits, to realize its full potential as therapeutic agent in different epithelial tumors.

Trop2-targeted therapy in breast cancer

Human trophoblastic cell surface antigen 2 (Trop2) is a glycoprotein, a cellular marker of trophoblastic and stem cells, and a calcium signaling transducer involved in several signaling pathways, leading to the proliferation, invasion, and metastasis of tumors. It is expressed at a low level in normal epithelial cells, but at a high level in many tumors, making it an ideal target for cancer therapy. According to previous literature, Trop2 is broadly expressed in all breast cancer subtypes, especially in triple negative breast cancer (TNBC). Several clinical trials have demonstrated the effectiveness of Trop2-targeted therapy in breast cancer. Sacituzumab govitecan (SG) is a Trop2-targeted antibody-drug conjugate (ADC) that has been approved for the treatment of metastatic TNBC and hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer. This article reviews the structure and function of Trop2, several major Trop2-targeted ADCs, other appealing novel Trop2-targeted agents and relevant clinical trials to provide a landscape of how Trop2-targeted treatments will develop in the future.

Sacituzumab Govitecan in patients with breast cancer brain metastases and recurrent glioblastoma: a phase 0 window-of-opportunity trial

Sacituzumab Govitecan (SG) is an antibody-drug conjugate that has demonstrated efficacy in patients with TROP-2 expressing epithelial cancers. In a xenograft model of intracranial breast cancer, SG inhibited tumor growth and increased mouse survival. We conducted a prospective window-of-opportunity trial (NCT03995706) at the University of Texas Health Science Center at San Antonio to examine the intra-tumoral concentrations and intracranial activity of SG in patients undergoing craniotomy for breast cancer with brain metastases (BCBM) or recurrent glioblastoma (rGBM). We enrolled 25 patients aged ≥18 years diagnosed with BCBM and rGBM to receive a single intravenous dose of SG at 10 mg/kg given one day before resection and continued on days 1 and 8 of 21-day cycles following recovery. The PFS was 8 months and 2 months for BCBM and rGBM cohorts, respectively. The OS was 35.2 months and 9.5 months, respectively. Grade≥3 AE included neutropenia (28%), hypokalemia (8%), seizure (8%), thromboembolic event (8%), urinary tract infection (8%) and muscle weakness of the lower limb (8%). In post-surgical tissue, the median total SN-38 was 249.8 ng/g for BCBM and 104.5 ng/g for rGBM, thus fulfilling the primary endpoint. Biomarker analysis suggests delivery of payload by direct release at target site and that hypoxic changes do not drive indirect release. Secondary endpoint of OS was 35.2 months for the BCBM cohort and 9.5 months for rGBM. Non-planned exploratory endpoint of ORR was 38% for BCBM and 29%, respectively. Exploratory endpoint of Trop-2 expression was observed in 100% of BCBM and 78% of rGBM tumors. In conclusion, SG was found to be well tolerated with adequate penetration into intracranial tumors and promising preliminary activity within the CNS. Trial Registration: Trial (NCT03995706) enrolled at Clinical Trials.gov as Neuro/Sacituzumab Govitecan/Breast Brain Metastasis/Glioblastoma/Ph 0: https://clinicaltrials.gov/study/NCT03995706?cond=NCT03995706 .

Sacituzumab Govitecan Demonstrates Efficacy across Tumor Trop-2 Expression Levels in Patients with Advanced Urothelial Cancer

PURPOSE

Human trophoblast cell surface antigen 2 (Trop-2) is a protein highly expressed in urothelial cancer (UC). Sacituzumab govitecan (SG) is a Trop-2-directed antibody drug conjugate with a hydrolysable linker and a potent SN-38 payload. This study explored Trop-2 expression in tumors treated with SG in cohorts 1 to 3 (C1-3) from the TROPHY-U-01 study and evaluated whether efficacy was associated with Trop-2 expression.

PATIENTS AND METHODS

TROPHY-U-01 (NCT03547973) is an open-label phase II study that assessed the efficacy and safety of SG (alone or in combinations) in patients with unresectable locally advanced or metastatic UC (mUC). Archival tumor samples collected at enrollment for C1-3 were analyzed for Trop-2 membrane expression by considering histological scores (H-scores; scale 0-300) and the percentage of membrane positive tumor cells at low magnification (4×). The association of Trop-2 with clinical endpoints [objective response rate (ORR), progression-free survival (PFS), and overall survival (OS)] was evaluated.

RESULTS

In C1-3, tissue was collected from 158 (82%) of 192 treated patients, and 146 (76%) had evaluable Trop-2 data. Trop-2 was highly expressed in tumor samples. The median [interquartile range (IQR)] Trop-2 H-score was 215 (180-246), and the median (IQR) percentage of membrane positive tumor cells was 91% (80-98). Trop-2 expression at any level was observed in 98% of patients. Furthermore, ORR, PFS, and OS benefits were observed across all Trop-2 expression levels.

CONCLUSIONS

Trop-2 protein is highly expressed in UC, as confirmed by examining tumors from patients enrolled in the TROPHY-U-01 trial. The results indicate that SG demonstrates efficacy in mUC across Trop-2 expression levels.

Overview of Systemic Therapies in Penile Cancer

Penile cancer (PC), although rare, poses significant challenges in both diagnosis and treatment. Penile squamous cell carcinoma (PSCC) represents the most common histologic subtype of PC, accounting for approximately 95% of cases. With limited therapeutic options available, systemic therapies have emerged as critical components in the management of advanced PSCC. Recent developments in clinical research have revealed the effectiveness of new therapeutic strategies. By elucidating the mechanism of action and clinical evidence supporting these treatments, we strive to offer insights into optimizing treatment strategies and enhancing the quality of care for patients affected by this complex disease.

Opportunities and Challenges in the Development of Antibody-Drug Conjugate for Triple-Negative Breast Cancer: The Diverse Choices and Changing Needs

Triple-negative breast cancer (TNBC) is a highly heterogeneous breast cancer subtype, which is also characterized by the aggressive phenotype, high recurrence rate, and poor prognosis. Antibody-drug conjugate (ADC) is a monoclonal antibody with a cytotoxic payload connected by a linker. ADC is gaining more and more attention as a targeted anti-cancer agent. Clinical studies of emerging ADC drugs such as sacituzumab govitecan and trastuzumab deruxtecan in patients with metastatic breast cancer (including TNBC) are progressing rapidly. In view of its excellent clinical efficacy and good tolerability, Sacituzumab govitecan gained accelerated approval by the FDA for the treatment of advanced metastatic TNBC in 2020. This review discusses the treatment status and challenges in TNBC, with an emphasis on the current status of ADC development and clinical trials in TNBC and metastatic breast cancer. We also summarize the clinical experience and future exploration directions of ADC development for TNBC patients.

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.