Upregulation of Trop-2 quantitatively stimulates human cancer growth

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.

Antibody-drug conjugates in urothelial carcinoma: current status and future

PURPOSE OF REVIEW

Antibody-drug conjugates (ADCs) are quickly becoming frontline standard of care in many tumor types, including urothelial carcinoma. This review summarizes recent clinical investigations into the use of ADCs targeting nectin-4, trophoblast cell surface antigen-2 (Trop-2), human epidermal growth factor receptor 2 (HER-2), and other antigens in urothelial carcinoma.

RECENT FINDINGS

This review covers efficacy and toxicity data of ADCs alone and in combination with immunotherapy; mechanisms of resistance; and preclinical studies that provide biological basis for clinical approaches.

SUMMARY

Enfortumab vedotin and sacituzumab govitecan can be used in an unselected group of patients with urothelial carcinoma whereas HER-2 ADCs have only been administered in those with high expression or amplification. Most are being studied in combination with immune checkpoint inhibitors. Data supports use of enfortumab vedotin in combination with pembrolizumab as first-line therapy in metastatic/unresectable locally advanced urothelial carcinoma. Sacituzumab govitecan may be used as later-line option in these patients. HER-2 therapy is still under investigation but has many recent promising results.

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.

[Diffuse interstitial lung disease induced by antibody-drug conjugates]

INTRODUCTION

Antibody-drug conjugates (ADCs) represent a promising new therapeutic class in non-small-cell lung cancer (NSCLC) patients. Studies assessing ADC have highlighted a pulmonary toxicity profile in the form of interstitial lung disease (ILD).

STATE OF THE ART

Several ADCs for NSCLC are currently being developed. In studies evaluating Trastuzumab-Deruxtecan (Her-2 target), incidence of drug-induced ILD ranged from 10.7 to 26.0%, and from 3.6 to 25.0% in those evaluating Datopotamab-Deruxtecan (TROP-2 target). Incidence of 9.9 and 5% of ILD was observed with Telisotuzumab-Vedotin (c-MET target) and Patritumab-Deruxtecan (Her-3 target), respectively. No cases of ILD have been reported with Sacituzumab-Govitecan (TROP-2 target) or Tusamitamab-Ravtansine (CEACAM5 target).

PERSPECTIVES

Several risk factors for ADC-induced ILD seem to emerge, including respiratory comorbidities, renal insufficiency, or type and dosage of ADC. Current studies are focusing on the combination of ADC and immunotherapy, although there are few data now available on pulmonary toxicity profiles.

CONCLUSION

Among the many ADCs being developed, several can cause ILD of varying grades and intensity. Knowledge of their risks, diagnostic and therapeutic modalities is required in order to quickly detect and treat ADC-induced ILD.

Trop-2 expression in non-small cell lung cancer

Trophoblast cell-surface antigen 2 (Trop-2) is highly expressed in non-small cell lung cancer (NSCLC) and has become an attractive target for antibody-drug conjugates (ADCs). ADC tumor target expression is essential in investigating the predictive value of Trop-2 and Trop-2 ADC efficacy. Although Trop-2 mRNA expression in NSCLC has been described, protein-level expression is poorly understood. We investigated Trop-2 expression landscape across multiple data and sample sets to characterize mRNA expression and address the gap in protein-expression profiling. Trop-2 expression was analyzed using available mRNA, mutation, and protein data in three datasets: (1) The Cancer Genome Atlas (TCGA) included clinical-pathological and survival data in NSCLC adenocarcinoma and squamous cell carcinoma; (2) sample set 1 (adenocarcinoma) and (3) sample set 2 (adenocarcinoma, squamous cell carcinoma) underwent sequencing and immunohistochemistry for Trop-2 RNA, protein (Robust Prototype Assay, SP295 clone) and mutation analysis. Trop-2 was highly expressed in NSCLC and expression was similar in adenocarcinoma and squamous cell carcinoma and across baseline characteristics including patient age, sex, and tumor stage. Trop-2 expression was not associated with clinically relevant genetic alterations. Trop-2 was not a prognostic factor in NSCLC (TCGA survival data). High Trop-2 expression in NSCLC was independent of evaluated baseline characteristics, histology, and driver alterations. Trop-2 protein expression at any level was observed in 82% to 90% of NSCLC across sample sets; similar proportions of adenocarcinoma and squamous cell carcinoma expressed Trop-2. These data support broad Trop-2 ADC use in NSCLC.

Sacituzumab tirumotecan in advanced non-small-cell lung cancer with or without EGFR mutations: phase 1/2 and phase 2 trials

Trophoblast cell-surface antigen 2 (TROP2)-directed antibody-drug conjugate (ADC) is a promising anticancer agent that has shown remarkable efficacy in several malignancies. However, in lung cancer, two phase 3 trials on TROP2-ADCs in unselected patients with advanced non-small-cell lung cancer (NSCLC) have both failed. Sacituzumab tirumotecan (sac-TMT) is a novel TROP2-directed ADC. Here we report the efficacy and safety of sac-TMT in previously treated, advanced NSCLC with or without activating EGFR mutations from the phase 1/2 KL264-01 and phase 2 SKB264-II-08 studies. Primary endpoint was objective response rate (ORR). KL264-01 enrolled EGFR-wild-type and EGFR-mutant NSCLC (n = 43). Confirmed ORR was 40% (17 of 43; 95% confidence interval (CI), 25-56). Median progression-free survival (PFS) was 6.2 months (95% CI, 5.3-11.3). Post-hoc subgroup analyses found better outcomes in the EGFR-mutant subset (22 of 43, 51%) with a confirmed ORR of 55% (12 of 22) and median PFS of 11.1 months. These findings were independently supported by results from SKB264-II-08, where sac-TMT led to confirmed ORR of 34% (22 of 64; 95% CI, 23-47) and median PFS of 9.3 months (95% CI, 7.6-11.4) in 64 patients with EGFR-mutant NSCLC. For a total of 107 patients receiving sac-TMT, the most common treatment-related adverse events were hematologic toxicities. Diarrhea (4%) and interstitial lung disease (1%) were uncommon. Exploration of potential mechanisms revealed that the presence of EGFR mutation substantially increased the internalization and activity of sac-TMT in vitro. Overall, sac-TMT showed encouraging single-agent activity and manageable tolerability in previously treated, advanced NSCLC with EGFR mutations. Randomized phase 3 trials in treatment-naive and previously treated patients with EGFR-mutant NSCLC are ongoing. ClinicalTrials.gov Identifiers: NCT04152499 , NCT05631262 .

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.

[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.

The Era of Antibody Drug Conjugates in Lung Cancer: Trick or Threat?

Antibody drug conjugates (ADCs) are a novel class of therapeutics that structurally are composed by an antibody directed to a tumor epitope connected via a linker to a cytotoxic payload, and that have shown significant antitumor activity across a range of malignancies including lung cancer. In this article we review the pharmacology and design of ADCs, as well as we describe the results of different studies evaluating ADCs in lung cancer directed to several targets including HER2, HER3, TROP2, MET, CEACAM5 and DLL3.

Camptothein-Based Anti-Cancer Therapies and Strategies to Improve Their Therapeutic Index

Camptothecin and its derivatives (CPTs) are potent antineoplastic agents that exert their effects by inhibiting DNA topoisomerase I, leading to apoptosis during cell proliferation. Since their discovery in the 1960s, CPTs have faced challenges such as low water solubility, pH-dependent lactone ring instability, and severe off-target toxicities. Despite extensive research, only two CPTs, irinotecan and topotecan, have received health authority approval. Ongoing clinical trials continue to explore the use of CPTs in combination with targeted therapies and immunotherapies to expand their clinical use. Drug delivery systems, including liposomes and antibody-drug conjugates (ADCs), have significantly enhanced the therapeutic index of CPTs. Liposomal irinotecan (Onivyde®, Ipsen, Paris, France) and two ADCs delivering CPT payloads, trastuzumab deruxtecan (Enhertu®, Daiichi Sankyo, Tokyo, Japan) and sacituzumab govitecan (Trodelvy®, Gilead Sciences, Inc., Foster City, CA, USA), have demonstrated substantial efficacy and safety. There is promise that novel strategies such as inverse targeting and co-dosing with anti-idiotypic distribution enhancers may expand the utility of CPT ADCs. This review highlights CPT therapies in clinical use and discusses approaches to further enhance their therapeutic selectivity.

Noninvasive molecular imaging using anti-Trop-2 aptamer for targeted therapy of small cell lung cancer

Recent advancements in antibody-drug conjugates (ADCs) targeting trophoblast surface cell antigen 2 (Trop-2) have brought important progress in the field of targeted therapy. This progress also holds promise for the treatment of small cell lung cancer (SCLC) as anti-Trop-2 therapy appears to have a safe and effective clinical activity in metastatic SCLC patients. However, effective treatments of anti-Trop-2 ADCs rely on the comprehensive assessment of Trop-2 expression at the tumor sites, SCLC exhibits intratumoral heterogeneity, making the accurate acquisition of histological biopsies a challenge. To address this issue, we herein report the development of an anti-Trop-2 aptamer consisting of 76 bases is specifically bind to Trop-2-overexpressing SCLC cells. Further truncated anti-Trop-2 aptamer with 46 nucleotides also possesses excellent in vitro and in vivo binding affinity with Trop-2 antigens. After radiolabeling with gallium-68 radionuclide, an aptamer-based molecular imaging probe was successfully fabricated named [68Ga]Ga-NOTA-TRP-c. This imaging probe demonstrated effective and precise differentiation of Trop-2-positive tumors in both murine- and human-derived animal models, exhibiting favorable metabolic profiles. Furthermore, Trop-2-positive SCLC tumors recognized by anti-Trop-2 aptamer can be treated with anti-Trop-2 ADC sacituzumab govitecan (SG), either in vitro or in vivo. Importantly, SG induces DNA damage and cell apoptosis without affecting the expression of Trop-2 on the cell surface, which makes it possible to use anti-Trop-2 aptamer to monitor the expression of Trop-2 in SCLC. This study highlights the potential of aptamer-based molecular imaging and imaging-guided SG treatment as a promising option for targeted therapy in SCLC.

Large, recursive membrane platforms are associated to Trop-1, Trop-2, and protein kinase signaling for cell growth

The transmembrane glycoproteins Trop-1/EpCAM and Trop-2 independently trigger Ca2+ and kinase signals for cell growth and tumor progression. Our findings indicated that Trop-1 and Trop-2 tightly colocalize at macroscopic, ruffle-like protrusions (RLP), that elevate from the cell perimeter, and locally recur over hundreds of seconds. These previously unrecognized elevated membrane regions ≥20-µm-long, up to 1.5 µm high were revealed by Z-stack analysis and three-dimensional reconstruction of signal transducer-hosting plasma membrane regions. Trop-2 stimulates cell growth through a membrane supercomplex that comprises CD9, PKCα, ion pumps, and cytoskeletal components. Our findings indicated that the growth-driving Trop-2 supercomplex assembles at RLP. RLP behaved as sites of clustering of signal transducers, of phosphorylation/activation of growth-driving kinases, as recruitment sites of PKCα and as origin of Ca2+ signaling waves, suggesting RLP to be novel signaling platforms in living cells. RLP were induced by growth factors and disappeared upon growth factor deprivation and β-actin depolymerization, candidating RLP to be functional platforms for high-dimensional signaling for cell growth.

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.

Exposure-Response Analyses of Sacituzumab Govitecan Efficacy and Safety in Patients With Metastatic Triple-Negative Breast Cancer

Sacituzumab govitecan (SG), a Trop-2-directed antibody-drug conjugate, is approved for patients with metastatic triple-negative breast cancer (mTNBC) who received ≥2 prior systemic therapies (≥1 in metastatic setting). Exposure-response (E-R) relationships between SG exposure and efficacy and safety outcomes were characterized in 277 patients with mTNBC using data from the phase I/II IMMU-132-01 and phase III ASCENT (IMMU-132-05) studies. Evaluated endpoints included complete response (CR), objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and safety endpoints (individual first worst grade of select adverse events (AEs)). E-R analyses were also conducted for time to first dose reduction or delay. Patients received SG at 8 or 10 mg/kg intravenously on days 1 and 8 of a 21-day cycle. Average SG-related serum exposure over the treatment duration (until the event) was consistently the most significant exposure metric correlated with efficacy and safety endpoints. Higher average concentration over the treatment duration for SG (CAVGSG) was the best predictor of CR and ORR. The model-predicted proportions of patients with CR and ORR at 10 mg/kg were 4.26% and 32.6%, respectively. Higher CAVG for total antibody was the best predictor of OS and PFS. The model-predicted probability of OS at 12 months at median lactate dehydrogenase (227 IU/L) was 53%. The probability of grade ≥1 evaluated AEs and the risk of dose reductions and delays significantly increased with increasing CAVGSG. The model-predicted proportions of patients with any-grade AEs were 35.9%, 67.4%, 64.7%, and 67.1% for vomiting, diarrhea, nausea, and neutropenia, respectively (10 mg/kg dose group). Neutropenia was the only evaluated AE for which CAVGSG was significantly associated with grade ≥3 events. The clinically meaningful efficacy and manageable safety achieved with SG 10 mg/kg on days 1 and 8 of every 21-day cycle dosing regimen supports the appropriateness of this clinical dosage in patients with mTNBC.

Warming-up the immune cell engagers (ICEs) era in breast cancer: state of the art and future directions

The advent of immune checkpoint inhibitors (ICIs) has deeply reshaped the therapeutic algorithm of triple-negative breast cancer (TNBC). However, there is considerable scope for better engagement of the immune system in other BC subtypes. ICIs have paved the way for investigations into emerging immunotherapeutic strategies, such as immune cell engagers (ICEs) that work by promoting efficient tumor cell killing through the redirection of immune system against cancer cells. Most ICEs are bispecific antibodies that simultaneously recognize and bind to both cancer and immune cells generating an artificial synapse. Major side effects are cytokine release syndrome, hepatotoxicity, and neurotoxicity related to inappropriate immune system activation. Here, we provide a comprehensive overview of this compounds, the available preclinical and clinical evidence supporting their investigation and development in BC also highlighting the challenges that have prevented their widespread use in oncology. Finally, major strategies are explored to broaden their use in BC.

Antibody-drug conjugates in breast cancer

Antibody-drug conjugates (ADCs) have garnered significant attention as an innovative therapeutic strategy in cancer treatment. The mechanism of action for ADCs involves the targeted delivery of antibodies to specific receptors, followed by the release of cytotoxic payloads directly into tumor cells. In recent years, ADCs have made substantial progress in the treatment of breast cancer (BC), particularly demonstrating significant efficacy in the human epidermal growth factor receptor-2 (HER-2)-positive subgroup. Clinical evidence indicates that ADCs have notably improved treatment efficacy and survival outcomes for BC patients. However, challenges such as drug toxicities and the emergence of drug resistance necessitate further research and discussion. In this paper, we will summarize the advances in ADCs targeting various receptors in BC patients and explore the challenges and future directions in this field. We anticipate that the increasing availability of ADCs will lead to more effective and personalized treatment options for BC patients.

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.

Unveiling the future of breast cancer therapy: Cutting-edge antibody-drug conjugate strategies and clinical outcomes

Breast cancer has become the most prevalent malignant tumor worldwide and remains one of the leading causes of cancer-related mortality among women globally. The prognosis for patients with metastatic breast cancer remains poor, necessitating the exploration of novel therapeutic strategies to improve survival rates. In the era of precision medicine, antibody-drug conjugates (ADCs) have gained significant attention as a targeted therapeutic strategy in breast cancer treatment. ADCs, a relatively new treatment for breast cancer, deliver cytotoxic drugs (payloads), directly into the tumor space, turning chemotherapy into a targeted agent, which enables patients to experience significant improvements with manageable drug toxicity. For the treatment of breast cancer, there are three ADCs approved for breast cancer treatment: Trastuzumab emtansine (T-DM1), Trastuzumab Deruxtecan (T-Dxd) targeting HER-2, and Sacituzumab Govitecan (SG) targeting Trop-2. Recent clinical studies have demonstrated that the benefits of ADC therapies extend beyond HER2-positive breast cancer toinclude hormone receptor (HR)-positive breast cancer, triple-negative breast cancer (TNBC), and HER2-low expressing breast cancer. Notably, the DESTINY-Breast series of studies, particularly focusing on T-Dxd, encompass neoadjuvant, adjuvant, and multiple lines of therapy for advanced breast cancer. This marks the advent of a comprehensive ADC era in breast cancer treatment. This review summarizes the efficacy and adverse effects of ADC therapies that have completed or are currently undergoing phase I-III clinical trials. Additionally, it analyzes potential combination strategies to overcome ADC resistance, aiming to provide clinicians with a comprehensive clinical guide to the use of ADCs in breast cancer treatment.

The Tumor-Associated Calcium Signal Transducer 2 (TACSTD2) oncogene is upregulated in cystic epithelial cells revealing a potential new target for polycystic kidney disease

Polycystic kidney disease (PKD) is an important cause of kidney failure, but treatment options are limited. While later stages of the disease have been extensively studied, mechanisms driving the initial conversion of kidney tubules into cysts are not understood. To identify genes with the potential to promote cyst initiation, we deleted polycystin-2 (Pkd2) in mice and surveyed transcriptional changes before and immediately after cysts developed. We identified 74 genes which we term cyst initiation candidates (CICs). To identify conserved changes with relevance to human disease we compared these murine CICs to single cell transcriptomic data derived from patients with PKD and from healthy controls. Tumor-associated calcium signal transducer 2 (Tacstd2) stood out as an epithelial-expressed gene with elevated levels early in cystic transformation that further increased with disease progression. Human tissue biopsies and organoids show that TACSTD2 protein is low in normal kidney cells but is elevated in cyst lining cells, making it an excellent candidate for mechanistic exploration of its role in cyst initiation. While TACSTD2 has not been studied in PKD, it has been studied in cancer where it is highly expressed in solid tumors while showing minimal expression in normal tissue. This property is being exploited by antibody drug conjugates that target TACSTD2 for the delivery of cytotoxic drugs. Our finding that Tacstd2/TACSTD2 is prevalent in cysts, but not normal tissue, suggests that it should be explored as a candidate for drug development in PKD. More immediately, our work suggests that PKD patients undergoing TACSTD2-directed treatment for breast and urothelial cancer should be monitored for kidney effects.

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.

Intraoperative evaluation of tumor margins using a TROP2 near-infrared imaging probe to enable human breast-conserving surgery

Intraoperative surgical margin assessment remains a challenge during breast-conserving surgery. Here, we report a combined strategy of immuno-positron emission tomography (PET) for preoperative detection of breast cancer and guided assessment of margins in breast-conserving surgery through second near-infrared (NIR-II) fluorescence imaging of trophoblastic cell surface antigen 2 (TROP2). We demonstrated that the intensity of PET signals in the tumors was nearly five times higher than in normal breast tissue with a zirconium-89 tracer conjugated to sacituzumab govitecan (SG) in a mouse spontaneous breast cancer model, enabling the identification of tumors. We further generated a NIR-II probe of indocyanine green conjugated to SG (ICG-SG) and developed a rapid incubation imaging method for intraoperative margin assessment in a relevant time window for the operation workflow. The ICG-SG NIR-II fluorescence image guidance was first verified to remove tumors completely and accurately in mouse breast cancer models. Moreover, the rapid incubation imaging method was applied to distinguish benign and malignant breast lesions in samples from 26 patients with breast cancer. Therefore, we have developed both nuclide and optical probes targeting TROP2 for rapid and precise identification of tumor margins during breast-conserving surgery in humans.

Novel antibody-drug conjugates based on DXd-ADC technology

In recent years, antibody-drug conjugate (ADC) technology, which uses monoclonal antibodies (mAbs) to specifically deliver effective cytotoxic payloads to tumor cells, has become a promising method of tumor targeted therapy. ADCs are a powerful class of biopharmaceuticals that link antibodies targeting specific antigens and small molecule drugs with potent cytotoxicity via a linker, thus enabling selective destruction of cancer cells while minimizing systemic toxicity. DXd is a topoisomerase I inhibitor that induces DNA damage leading to cell cycle arrest, making it an option for ADC payloads. The DXd-ADC technology, developed by Daiichi Sankyo, is a cutting-edge platform that produces a new generation of ADCs with improved therapeutic metrics and has shown significant therapeutic potential in various types of cancer. This review provides a comprehensive assessment of drugs developed with DXd-ADC technology, with a focus on mechanisms of action, pharmacokinetics studies, preclinical data, and clinical outcomes for DS-8201a, U3-1402, DS-1062a, DS-7300a, DS-6157a, and DS-6000a. By integrating existing data, we aim to provide valuable insights into the current therapeutic status and future prospects of these novel agents.

Preclinical activity of datopotamab deruxtecan, a novel TROP2 directed antibody-drug conjugate targeting trophoblast cell-surface antigen 2 (TROP2) in ovarian carcinoma

INTRODUCTION

Epithelial ovarian cancer (EOC) is associated with the highest gynecologic cancer mortality. The development of novel, effective combinations of targeted therapeutics remains an unmet medical need. We evaluated the preclinical activity of datopotamab deruxtecan (Dato-Dxd), a novel TROP2 targeting antibody drug conjugate (ADC) in ovarian cancer cell lines and xenografts with variable TROP2 expression.

METHODS

In vitro cell viability with Dato-DXd was assessed using flow-cytometry based assays against a panel of EOC primary cell lines with variable TROP2 expression. Fluorescent anti-phospho-histone H2A.X antibody was used to detect dsDNA breaks by flow-cytometry. The in vivo antitumor activity of Dato-DXd was tested in TROP2 overexpressing xenografts.

RESULTS

TROP2 overexpressing (3+) and moderate (2+) expressing EOC cell lines demonstrated higher sensitivity to Dato-DXd when compared to TROP2 negative tumors. Dato-DXd exposed TROP2+ EOC demonstrated increased dsDNA breaks and Annexin-V positivity (a marker of apoptosis) when compared to tumor cells exposed to the non-binding conjugate (p = 0.001 and p = 0.016, respectively). Dato-DXd induced significant antibody-dependent cellular cytotoxicity (ADCC) in the presence of peripheral-blood-lymphocytes. While negligible activity was detected against EOC cell lines with low TROP2 expression, Dato-DXd demonstrated significant bystander killing against tumor cells with low/negligible TROP2 when such cells were admixed with TROP2 3+ tumor cells in vitro. Dato-DXd showed tumor growth suppression against EOC cell line derived xenograft models that overexpress TROP2 at 3+ levels, prolonging survival when compared to controls, with minimal toxicity.

CONCLUSION

Dato-DXd shows promising preclinical activity against TROP2 overexpressing ovarian cancers. Future clinical trials in ovarian cancer patients are warranted.

Novel Anti-Trop2 Nanobodies Disrupt Receptor Dimerization and Inhibit Tumor Cell Growth

Background: Trop2 (trophoblast cell-surface antigen 2) is overexpressed in multiple malignancies and is closely associated with poor prognosis, thus positioning it as a promising target for pan-cancer therapies. Despite the approval of Trop2-targeted antibody-drug conjugates (ADCs), challenges such as side effects, drug resistance, and limited efficacy persist. Recent studies have shown that the dimeric forms of Trop2 are crucial for its oncogenic functions, and the binding epitopes of existing Trop2-targeted drugs lie distant from the dimerization interface, potentially limiting their antitumor efficacy. Method: A well-established synthetic nanobody library was screened against Trop2-ECD. The identified nanobodies were extensively characterized, including their binding specificity and affinity, as well as their bioactivities in antigen-antibody endocytosis, cell proliferation, and the inhibition of Trop2 dimer assembly. Finally, ELISA based epitope analysis and AlphaFold 3 were employed to elucidate the binding modes of the nanobodies. Results: We identified two nanobodies, N14 and N152, which demonstrated high affinity and specificity for Trop2. Cell-based assays confirmed that N14 and N152 can facilitate receptor internalization and inhibit growth in Trop2-positive tumor cells. Epitope analysis uncovered that N14 and N152 are capable of binding with all three subdomains of Trop2-ECD and effectively disrupt Trop2 dimerization. Predictive modeling suggests that N14 and N152 likely target the epitopes at the interface of Trop2 cis-dimerization. The binding modality and mechanism of action demonstrated by N14 and N152 are unique among Trop2-targeted antibodies. Conclusions: we identified two novel nanobodies, N14 and N152, that specifically bind to Trop2. Importantly, these nanobodies exhibit significant anti-tumor efficacy and distinctive binding patterns, underscoring their potential as innovative Trop2-targeted therapeutics.

Canadian Expert Recommendations on Safety Overview and Toxicity Management Strategies for Sacituzumab Govitecan Based on Use in Metastatic Triple-Negative Breast Cancer

Sacituzumab Govitecan (SG) is an antibody-drug conjugate (ADC) comprised of an anti-Trop-2 IgG1 molecule conjugated to SN-38, the active metabolite of irinotecan, via a pH-sensitive hydrolysable linker. As a result of recent Canadian funding for SG in advanced hormone receptor (HR)-positive breast cancer and triple-negative breast cancer (TNBC), experience with using SG and managing adverse events (AEs) has grown. This review presents a summary of evidence and adverse event recommendations derived from Canadian experience, with SG use in metastatic TNBC for extrapolation and guidance in all indicated settings. SG is dosed at 10 mg/kg on day 1 and day 8 of a 21-day cycle. Compared to treatment of physicians' choice (TPC) the phase III ASCENT and TROPiCS-02 studies demonstrated favorable survival data in unresectable locally advanced or metastatic TNBC and HR-positive HER2 negative metastatic breast cancer, respectively. The most common AEs were neutropenia, diarrhea, nausea, fatigue, alopecia, and anemia. This review outlines AE management recommendations for SG based on clinical trial protocols and Canadian guidelines, incorporating treatment delay, dose reductions, and the use of prophylactic and supportive medications.

Sacituzumab-govitecan in metastatic triple-negative breast cancer: a multicenter effectiveness and safety study

Aim: Sacituzumab-govitecan (Sgov) is a new antibody-drug conjugate recently approved for metastatic triple negative breast cancer (mTNBC), so there are still few data published in the real-world setting.Materials & methods: This study was to analyze the effectiveness and safety of Sgov in mTNBC of patients from the three main hospitals of a city and to compare with the pivotal ASCENT-trial. A total of 46 patients were included, all women diagnosed with mTNBC, with a median age of 52 years and Eastern Cooperative Oncology Group performance status 0-1 71.8% of patients.Results: Sgov effectiveness data seem to be slightly inferior than expected. Furthermore, it is observed that patients with an Eastern Cooperative Oncology Group of two or higher benefit significantly less from treatment with the drug. Safety profile of Sgov is acceptable.

Unveiling the placental secrets: Exploring histopathological changes and TROP2 expression in intrahepatic cholestasis of pregnancy

INTRODUCTION

Gestational cholestasis, also known as intrahepatic cholestasis of pregnancy (ICP) or obstetric cholestasis, is a liver disease that can manifest in late pregnancy. Trophoblast cell surface antigen (TROP2) is a type I transmembrane glycoprotein identified in placental trophoblast cells that plays a critical role in trophoblast invasion of the decidua upon implantation into the placenta. Our study aims to investigate the role of TROP2 in pregnancy cholestasis.

MATERIALS AND METHODS

Study groups: Group 1 (control group) (n = 10): consists of healthy normal pregnant women without any disease, Group 2 (cholestasis group) (n = 10): consists of pregnant women diagnosed with cholestasis. After routine histological follow-up, hematoxylin and eosin staining and TROP2 immunostaining were performed and scored.

RESULTS

In the cholestasis group, in contrast to the control group, thrombus structures were observed in the intervillous space. In the cholestasis group compared to the control group, villus mesenchymal connective tissue cells, capillary endothelium and trophoblasts around the villus showed significantly stronger anti-TROP2 staining (p < 0.05).

DISCUSSION

Cholestasis, a condition that may manifest during pregnancy, may be associated not only with observable pathological changes in placental tissues at the light microscopic level, but also with an increase in TROP2 expression. Given the critical role of TROP2 in trophoblast invasion during placental implantation, we hypothesize that TROP2 may serve as a key marker of the cholestatic processes occurring during pregnancy.

New therapeutic target molecules for gastric and gastroesophageal junction cancer

Molecularly targeted therapy for receptor tyrosine kinases (RTKs) has faced limitations in gastric and gastroesophageal junction (G/GEJ) cancer except for HER2-targeted agents, possibly due to inappropriate assay selection that has hindered identification of sensitive patients, in addition to coexisting genetic abnormalities as well as intratumoral heterogeneity. Immunohistochemistry of RTKs has, thus, proved largely unsuccessful for patient selection, and detection of RTK gene amplification as a true oncogenic driver is problematic given the small numbers of affected individuals. FGFR2 amplification is associated with poor prognosis in G/GEJ cancer, and immunohistochemistry of the FGFR2b protein isoform has proved effective for the detection of such FGFR2-dependent tumors. Phase III and Ib/III trials of the FGFR2-targeted antibody bemarituzumab for G/GEJ cancer overexpressing FGFR2b are ongoing based on the promising result in a phase II trial, especially in cases with an FGFR2b positivity of ≥ 10%. Challenges to EGFR- and MET-targeted therapies are being tackled with antibody-drug conjugates (ADCs) and bispecific antibodies. CLDN18.2 is expressed in some G/GEJ tumors but lacks oncogenic driver potential, and the CLDN18.2-targeted antibody zolbetuximab prolonged the survival of CLDN18.2-positive G/GEJ cancer patients in phase III trials. Antibody-drug conjugates and ADCs that target CLDN18.2 are also being pursued for treatment of such patients. Similarly, targeting of nondriver molecules such as DKK1, TROP2, and CEACAM5 is under investigation in early-stage clinical trials. This shift in focus from target molecules with driver potential to markers for precise drug delivery should increase the number of possible targets in G/GEJ cancer.

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 .

Antibody-drug conjugates treatment of small cell lung cancer: advances in clinical research

Small cell lung cancer (SCLC) is an extremely aggressive cancer with a relatively low median survival rate after diagnosis. Treatment options such as chemotherapy or combination immunotherapy have shown clinical benefits, but resistance and relapse can occur. Antibody-drug conjugates (ADCs), as a novel class of biopharmaceutical compounds, have broad application prospects in the treatment of SCLC. ADCs consist of monoclonal antibodies that specifically target cancer cells and are attached to cytotoxic drugs, allowing for targeted killing of cancer cells while sparing healthy tissues. Current clinical studies focus on Delta-like protein 3 (DLL3), CD56, Trophoblast cell surface antigen 2 (Trop-2), B7-H3, and SEZ6. Although toxicities exceeding expectations have been observed with Rova-T, drugs targeting TROP-2 (Sacituzumab Govitecan), B7-H3 (DS-7300), and SEZ6 (ABBV-011) have shown exciting clinical benefits. In this review, we collect the latest clinical evidence to describe the therapeutic efficacy and safety of ADCs in SCLC and discuss prospects and challenges.

New insights into the function and pathophysiology of the ectodomain sheddase A Disintegrin And Metalloproteinase 10 (ADAM10)

The 'A Disintegrin And Metalloproteinase 10' (ADAM10) has gained considerable attention due to its discovery as an 'α-secretase' involved in the nonamyloidogenic processing of the amyloid precursor protein, thereby possibly preventing the excessive generation of the amyloid beta peptide, which is associated with the pathogenesis of Alzheimer's disease. ADAM10 was found to exert many additional functions, cleaving about 100 different membrane proteins. ADAM10 is involved in many pathophysiological conditions, ranging from cancer and autoimmune disorders to neurodegeneration and inflammation. ADAM10 cleaves its substrates close to the plasma membrane, a process referred to as ectodomain shedding. This is a central step in the modulation of the functions of cell adhesion proteins and cell surface receptors. ADAM10 activity is controlled by transcriptional and post-translational events. The interaction of ADAM10 with tetraspanins and the way they functionally and structurally depend on each other is another topic of interest. In this review, we will summarize findings on how ADAM10 is regulated and what is known about the biology of the protease. We will focus on novel aspects of the molecular biology and pathophysiology of ADAM10 that were previously poorly covered, such as the role of ADAM10 on extracellular vesicles, its contribution to virus entry, and its involvement in cardiac disease, cancer, inflammation, and immune regulation. ADAM10 has emerged as a regulator controlling cell surface proteins during development and in adult life. Its involvement in disease states suggests that ADAM10 may be exploited as a therapeutic target to treat conditions associated with a dysfunctional proteolytic activity.

The combination of immune checkpoint inhibitors and antibody-drug conjugates in the treatment of urogenital tumors: a review insights from phase 2 and 3 studies

With the high incidence of urogenital tumors worldwide, urinary system tumors are among the top 10 most common tumors in men, with prostate cancer ranking first and bladder cancer fourth. Patients with resistant urogenital tumors often have poor prognosis. In recent years, researchers have discovered numerous specific cancer antigens, which has led to the development of several new anti-cancer drugs. Using protein analysis techniques, researchers developed immune checkpoint inhibitors (ICIs) and antibody-conjugated drugs (ADCs) for the treatment of advanced urogenital tumors. However, tumor resistance often leads to the failure of monotherapy. Therefore, clinical trials of the combination of ICIs and ADCs have been carried out in numerous centers around the world. This article reviewed phase 2 and 3 clinical studies of ICIs, ADCs, and their combination in the treatment of urogenital tumors to highlight safe and effective methods for selecting individualized therapeutic strategies for patients. ICIs activate the immune system, whereas ADCs link monoclonal antibodies to toxins, which can achieve a synergistic effect when the two drugs are combined. This synergistic effect provides multiple advantages for the treatment of urogenital tumors.

Comparison of Anti-Trop2 Extracellular Domain Antibodies Generated Against Peptide and Protein Immunogens for Targeting Trop2-Positive Tumour Cells

Trophoblast antigen 2 (Trop2) is a transmembrane glycoprotein upregulated in multiple solid tumours. Trop2-based passive immunotherapies are in clinical trials, while Trop2 targeting CAR-T cell-based therapies are also reported. Information about its T- and B-cell epitopes is needed for it to be pursued as an active immunotherapeutic target. This study focused on identification of immunodominant epitopes in the Trop2 extracellular domain (ECD) that can mount an efficient anti-Trop2 antibody response. In silico analysis using various B-cell epitope prediction tools was carried out to identify linear and conformational B-cell epitopes in the ECD of Trop2. Three linear peptide immunogens were shortlisted and synthesized. Along with linear peptides, truncated Trop2 ECD that possesses combination of linear and conformational epitopes was also selected. Recombinant protein immunogen was produced in 293-F suspension culture system and affinity purified. Antisera against different immunogens were characterized by ELISA and Western blotting. Two anti-peptide antisera detected recombinant and ectopically expressed Trop2 protein; however, they were unable to recognize the endogenous Trop2 protein expressed by cancer cells. Antibodies against truncated Trop2 ECD could bind to the endogenous Trop2 expressed on the surface of cancer cells. In addition to their high avidity, these polyclonal anti-sera against truncated Trop2 protein also mediated antibody-dependent cell-mediated cytotoxicity (ADCC). In summary, our comparative analysis demonstrated the utility of truncated Trop2 ECD as a promising candidate to be pursued as an active immunotherapeutic molecule against Trop2-positive cancer cells.

Final Results From the Randomized Phase III ASCENT Clinical Trial in Metastatic Triple-Negative Breast Cancer and Association of Outcomes by Human Epidermal Growth Factor Receptor 2 and Trophoblast Cell Surface Antigen 2 Expression

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Sacituzumab govitecan (SG), a first-in-class anti-trophoblast cell surface antigen 2 (Trop-2) antibody-drug conjugate, demonstrated superior efficacy over single-agent chemotherapy (treatment of physician's choice [TPC]) in patients with metastatic triple-negative breast cancer (mTNBC) in the international, multicenter, phase III ASCENT study.Patients were randomly assigned 1:1 to receive SG or TPC until unacceptable toxicity/progression. Final efficacy secondary end point analyses and post hoc analyses of outcomes stratified by Trop-2 expression and human epidermal growth factor receptor 2 status are reported. Updated safety analyses are provided.In this final analysis, SG (n = 267) improved median progression-free survival (PFS; 4.8 v 1.7 months; hazard ratio (HR), 0.41 [95% CI, 0.33 to 0.52]) and median overall survival (OS; 11.8 v 6.9 months; HR, 0.51 [95% CI, 0.42 to 0.63]) over TPC (n = 262). SG improved PFS over TPC in each Trop-2 expression quartile (n = 168); a trend was observed for improved OS across quartiles. Overall, SG had a manageable safety profile, with ≤5% of treatment-related discontinuations because of adverse events and no treatment-related deaths. The safety profile was consistent across all subgroups.These data confirm the clinical benefit of SG over chemotherapy, reinforcing SG as an effective treatment option in patients with mTNBC in the second line or later.

Expression of Potential Antibody-Drug Conjugate Targets in Cervical Cancer

(1) Background: There is a huge unmet clinical need for novel treatment strategies in advanced and recurrent cervical cancer. Several cell membrane-bound molecules are up-regulated in cancer cells as compared to normal tissue and have revived interest with the introduction of antibody-drug conjugates (ADCs). (2) Methods: In this study, we characterize the expression of 10 potential ADC targets, TROP2, mesotheline, CEACAM5, DLL3, folate receptor alpha, guanylatcyclase, glycoprotein NMB, CD56, CD70 and CD138, on the gene expression level. Of these, the three ADC targets TROP2, CEACAM5 and CD138 were further analyzed on the protein level. (3) Results: TROP2 shows expression in 98.5% (66/67) of cervical cancer samples. CEACAM5 shows a stable gene expression profile and overall, 68.7% (46/67) of cervical cancer samples are CEACAM-positive with 34.3% (23/67) of cervical cancer samples showing at least moderate or high expression. Overall, 73.1% (49/67) of cervical cancer samples are CD138-positive with 38.8% (26/67) of cervical cancer samples showing at least moderate or high expression. (4) Conclusions: TROP2, CEACAM5 or CD138 do seem suitable for further clinical research and the data presented here might be used to guide further clinical trials with ADCs in advanced and recurrent cervical cancer patients.

The Safety and Efficacy of the Combination of Sacituzumab Govitecan and Palliative Radiotherapy-A Retrospective Multi-Center Cohort Study

Sacituzumab govitecan (SG) is a new treatment option for patients with metastatic triple-negative and hormone receptor-positive, HER2-negative breast cancer. This antibody-drug conjugate is currently approved as monotherapy. Palliative radiotherapy is frequently used to treat symptomatic metastases locally. Concurrent use of SG and irradiation was excluded in clinical trials of SG, and there are currently limited published data. We report here a systematic review, as well as a retrospective multi-center study of 17 patients with triple-negative breast cancer who received concurrent SG and radiotherapy. In these patients, concurrent use was found to be efficient, safe and well tolerated. There were no apparent differences in moderate or severe acute toxicity according to the timing of SG administration.

Therapy for Hormone Receptor-Positive, Human Epidermal Growth Receptor 2-Negative Metastatic Breast Cancer Following Treatment Progression via CDK4/6 Inhibitors: A Literature Review

Endocrine therapy (ET) with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) is currently the first-line standard treatment for most patients with hormone receptor-positive (HR+) and human epidermal growth receptor 2-negative (HER2-) metastatic or advanced breast cancer. However, the majority of tumors response to and eventually develop resistance to CDK4/6is. The mechanisms of resistance are poorly understood, and the optimal postprogression treatment regimens and their sequences continue to evolve in the rapidly changing treatment landscape. In this review, we generally summarize the mechanisms of resistance to CDK4/6is and ET, and describe the findings from clinical trials using small molecule inhibitors, antibody-drug conjugates and immunotherapy, providing insights into how these novel strategies may reverse treatment resistance, and discussing how some have not translated into clinical benefit. Finally, we provide rational treatment strategies based on the current emerging evidence.

Biomarkers for Antibody-Drug Conjugates in Solid Tumors

The clinical development and then the progressive entry in clinical practice of antibody-drug conjugates (ADC) have marked a transformative advancement in the overall cancer treatment. ADCs have been extensively tested for a large number of tumors, reporting heterogeneous clinical efficacy and safety results. In some diseases, the advent of ADCs has yielded significant changes in the prognostic trajectory, portending an improvement of the survival and/or quality of life. ADCs are targeted agents, capable of delivering highly cytotoxic payloads selectively to antigen-expressing cancer cells. As such, they have been intended as perfect "bullets" to enable the promise of precision medicine, toward high-efficacy and limited-toxicity treatment options. However, only some approved ADCs are intended for the use in biomarker-selected patient populations, restricting potentially the opportunity to be more precise. Yet, key characteristics of modern ADCs might allow the activity of ADCs in tumors with heterogeneous or low expression of cancer antigens, resulting in a clinical activity that could sublimate the classic paradigm of a drug-to-target perfect match. In our review, we portrayed the current landscape of approved ADCs, reporting data of activity as related to the expression of the cancer antigens, and elucidating possible determinants of the safety and efficacy, including when used in a therapeutic sequence.

Targeting Trop2 by Bruceine D suppresses breast cancer metastasis by blocking Trop2/β-catenin positive feedback loop

INTRODUCTION

Tumor-associated calcium signal transducer 2 (Trop2) has been used as a transport gate for cytotoxic agents into cells in antibody-drug conjugate designs because of its expression in a wide range of solid tumors. However, the specific role of Trop2 itself in breast cancer progression remains unclear and small molecules targeting Trop2 have not yet been reported.

OBJECTIVES

To screen small molecules targeting Trop2, and to reveal its pharmacological effects and the molecular mechanisms of action.

METHODS

Small molecule targeting Trop2 was identified by cell membrane chromatography, and validated by cellular thermal shift assay and point mutation analyses. We investigated the pharmacological effects of Trop2 inhibitor using RNA-seq, human foreskin fibroblast (HFF)-derived extracellular matrix (ECM), Matrigel drop invasion assays, colony-forming assay, xenograft tumor model, 4T1 orthotopic metastasis model and 4T1 experimental metastasis model. The molecular mechanism was determined using immunoprecipitation, mass spectrometry, immunofluorescence, immunohistochemistry and Western blotting.

RESULTS

Here we identified Bruceine D (BD) as the inhibitor of Trop2, and demonstrated anti-metastasis effects of BD in breast cancer. Notably, Lys307 and Glu310 residues of Trop2 acted as critical sites for BD binding. Mechanistically, BD suppressed Trop2-induced cancer metastasis by blocking the formation of Trop2/β-catenin positive loop, in which the Trop2/β-catenin complex prevented β-catenin from being degraded via the ubiquitin-proteosome pathway. Destabilized β-catenin caused by BD reduced nucleus translocation, leading to the reduction of transcription of Trop2, the reversal of epithelial-mesenchymal transition (EMT) process, and the inhibition of ECM remodeling, further inhibiting cancer metastasis. Additionally, the inhibitory effects of BD on lung metastatic colonization and the beneficial effects of BD on prolongation of survival were validated in 4T1 experimental metastasis model.

CONCLUSIONS

These results support the tumor-promoting role of Trop2 in breast cancer by stabilizing β-catenin in Trop2/β-catenin positive loop, and suggest Bruceine D as a promising candidate for Trop2 inhibition.

Antibody-Drug Conjugates in Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) accounts for 15%-20% of all breast cancer. It is a heterogeneous breast cancer subtype with a poor prognosis. Given these negative features, there is a need for new treatment options beyond conventional chemotherapy in both the early stage and palliative setting. Impressive results have been reported with antibody-drug conjugates (ADCs) that link a cytotoxic payload to a monoclonal antibody, such as sacituzumab govitecan and trastuzumab deruxtecan, in the metastatic stage. The focus of this review is to discuss completed and ongoing trials involving ADCs in TNBC.

TROP2 is highly expressed in triple-negative breast cancer CTCs and is a potential marker for epithelial mesenchymal CTCs

Circulating tumor cells (CTCs) are the seeds of distant metastases of malignant tumors and are associated with malignancy and risk of metastasis. However, tumor cells undergo epithelial-mesenchymal transition (EMT) during metastasis, leading to the emergence of different types of CTCs. Real-time dynamic molecular and functional typing of CTCs is necessary to precisely guide personalized treatment. Most CTC detection systems are based on epithelial markers that may fail to detect EMT CTCs. Therefore, it is clinically important to identify new markers of different CTC types. In this study, bioinformatics analysis and experimental assays showed that trophoblast cell surface antigen 2 (TROP2), a target molecule for advanced palliative treatment of triple-negative breast cancer (TNBC), was highly expressed in TNBC tissues and tumor cells. Furthermore, TROP2 can promote the migration and invasion of TNBC cells by upregulating EMT markers. The specificity and potential of TROP2 as an EMT-associated marker of TNBC CTCs were evaluated by flow cytometry, immunofluorescence, spiking experiments, and a well-established CTC assay. The results indicated that TROP2 is a potential novel CTC marker associated with EMT, providing a basis for more efficacious markers that encompass CTC heterogeneity in patients with TNBC.

Current and emerging treatment approaches for hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer

In the past decade, significant progress was made in treating hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC), but many clinical questions remain. Cyclin-dependent kinase 4/6 inhibitors are now widely used in combination with endocrine therapy (ET) as standard of care, having demonstrated significant progression-free survival versus ET, and also significant overall survival benefits in the metastatic setting. Inhibition of the PI3K/AKT/mTOR intracellular signaling pathway coupled with ET typically follows first-line therapies. Novel endocrine options including oral selective estrogen receptor down-regulators (SERDs) are in late phases of development, with elacestrant being the first oral SERD to be approved for ESR1-mutant mBC. However, endocrine-refractory disease is inevitable in most patients and represents an area of unmet need, with current recommended options offering poor efficacy, undesirable toxicity, and reduced quality of life. Breakthrough advances in the metastatic setting came via the development of antibody-drug conjugates, which have the advantage of delivering cytotoxic payloads to tumor cells with higher tumor selectivity. Trastuzumab deruxtecan offers a novel therapeutic option for patients with HR+/HER2-low mBC and sacituzumab govitecan is a novel therapeutic option for patients with HR+/HER2- mBC, including those with unmet treatment need in the later-line endocrine-refractory setting. Data gaps still exist regarding optimal sequencing of these novel agents; additional studies into mechanisms of resistance in the metastatic setting would provide further insights. Herein, we describe the current treatment options for HR+/HER2- mBC, including the latest practice-impacting data, and provide commentary on future directions.

Comparative expression of trophoblast cell-surface antigen 2 (TROP2) in the different molecular subtypes of invasive breast carcinoma: An immunohistochemical study of 94 therapy-naive primary breast tumors

BACKGROUND

Sacituzumab govitecan, targeting trophoblast cell-surface antigen 2 (TROP2), is approved for the treatment of triple-negative and hormone receptor-positive/HER2-negative breast cancers. However, detailed studies comparing TROP2 protein expression in the different molecular subtypes of breast cancer are limited, and definitive evidence supporting the use of TROP2 as a biomarker for predicting response to this agent in patients with breast cancer is currently lacking.

OBJECTIVE

To compare the expression of TROP2 in the different molecular subtypes of breast cancer.

METHODS

Immunohistochemical staining for TROP2 was performed on 94 therapy-naive primary invasive breast carcinomas, including 25 luminal A-like, 25 luminal B-like, 19 HER2-like, and 25 triple-negative tumors.

RESULTS

Intermediate to high levels of TROP2 expression were observed in the majority of carcinomas of each molecular subtype, with a wide range of expression in each subtype. Occasional tumors with low or absent TROP2 expression were encountered, including two metaplastic carcinomas which were completely negative for TROP2.

CONCLUSIONS

Our observations support the continued investigation of the efficacy of sacituzumab govitecan in all molecular subtypes of breast carcinoma. Furthermore, the observed wide range of expression of TROP2 suggests that TROP2 may have potential utility as a biomarker for predicting responsiveness to sacituzumab govitecan. If this proves to be the case, then immunohistochemical staining for TROP2 would be critical for identifying those patients whose tumors are completely negative for TROP2, since these patients may be least likely or unlikely to respond to this agent, and alternative therapies may be more appropriate in such instances.

Advances in the study of marketed antibody-drug Conjugates (ADCs) for the treatment of breast cancer

Breast cancer continues to have a high incidence rate among female malignancies. Despite significant advancements in treatment modalities, the heterogeneous nature of breast cancer and its resistance to various therapeutic approaches pose considerable challenges. Antibody-drug conjugates (ADCs) effectively merge the specificity of antibodies with the cytotoxicity of chemotherapeutic agents, offering a novel strategy for precision treatment of breast cancer. Notably, trastuzumab emtansine (T-DM1) has provided a new therapeutic option for HER2-positive breast cancer patients globally, especially those resistant to conventional treatments. The development of trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG) has further broadened the applicability of ADCs in breast cancer therapy, presenting new hopes for patients with low HER2 expression and triple-negative breast cancer. However, the application of ADCs presents certain challenges. For instance, their treatment may lead to adverse reactions such as interstitial lung disease, thrombocytopenia, and diarrhea. Moreover, prolonged treatment could result in ADCs resistance, complicating the therapeutic process. Economically, the high costs of ADCs might hinder their accessibility in low-income regions. This article reviews the structure, mechanism of action, and clinical trials of commercially available ADCs for breast cancer treatment, with a focus on the clinical trials of the three drugs, aiming to provide insights for clinical applications and future research.

Loss of TROP2 and epithelial cell adhesion molecule expression is linked to grade progression in pTa but unrelated to disease outcome in pT2-4 urothelial bladder carcinomas

Introduction

Trophoblast cell surface antigen 2 (TROP2; EpCAM2) is a transmembrane glycoprotein which is closely related to EpCAM (EpCAM; EpCAM1). Both proteins share partial overlapping functions in epithelial development and EpCAM expression but have not been comparatively analyzed together in bladder carcinomas. TROP2 constitutes the target for the antibody-drug conjugate Sacituzumab govitecan (SG; TrodelvyTM) which has been approved for treatment of metastatic urothelial carcinoma by the United States Food and Drug administration (FDA) irrespective of its TROP2 expression status.

Methods

To evaluate the potential clinical significance of subtle differences in TROP2 and EpCAM expression in urothelial bladder cancer, both proteins were analyzed by multiplex fluorescence immunohistochemistry in combination with a deep-learning based algorithm for automated cell detection on more than 2,700 urothelial bladder carcinomas in a tissue microarray (TMA) format.

Results

The staining pattern of TROP2 and EpCAM were highly similar. For both proteins, the staining intensity gradually decreased from pTa G2 low grade (TROP2: 68.8±36.1; EpCAM: 21.5±11.7) to pTa G2 high grade (64.6±38.0; 19.3±12.2) and pTa G3 (52.1±38.7; 16.0±13.0, p<0.001 each). In pT2-4 carcinomas, the average TROP2 and EpCAM staining intensity was intermediate (61.8±40.9; 18.3±12.3). For both proteins, this was significantly lower than in pTa G2 low grade (p<0.001 each) but also higher than in pTa G3 tumors (p=0.022 for TROP2, p=0.071 for EpCAM). Within pT2-4 carcinomas, the TROP2 and EpCAM staining level was unrelated to pT, grade, UICC-category, and overall or tumor-specific patient survival. The ratio TROP2/EpCAM was unrelated to malignant phenotype and patient prognosis.

Conclusion

Our data show that TROP2 and EpCAM expression is common and highly interrelated in urothelial neoplasms. Despite of a progressive loss of TROP2/EpCAM during tumor cell dedifferentiation in pTa tumors, the lack of associations with clinicopathological parameters in pT2-4 cancer argues against a major cancer driving role of both proteins for the progression of urothelial neoplasms.

Phylogenetic conservation of Trop-2 across species-rodent and primate genomics model anti-Trop-2 therapy for pre-clinical benchmarks

A phylogenetic conservation analysis of Trop-2 across vertebrate species showed a high degree of sequence conservation, permitting to explore multiple models as pre-clinical benchmarks. Sequence divergence and incomplete conservation of expression patterns were observed in mouse and rat. Primate Trop-2 sequences were found to be 95%-100% identical to the human sequence. Comparative three-dimension primate Trop-2 structures were obtained with AlphaFold and homology modeling. This revealed high structure conservation of Trop-2 (0.66 ProMod3 GMQE, 0.80-0.86 ± 0.05 QMEANDisCo scores), with conservative amino acid changes at variant sites. Primate TACSTD2/TROP2 cDNAs were cloned and transfectants for individual ORF were shown to be efficiently recognized by humanized anti-Trop-2 monoclonal antibodies (Hu2G10, Hu2EF). Immunohistochemistry analysis of Macaca mulatta (rhesus monkey) tissues showed Trop-2 expression patterns that closely followed those in human tissues. This led us to test Trop-2 targeting in vivo in Macaca fascicularis (cynomolgus monkey). Intravenously injected Hu2G10 and Hu2EF were well tolerated from 5 to 10 mg/kg. Neither neurological, respiratory, digestive, urinary symptoms, nor biochemical or hematological toxicities were detected during 28-day observation. Blood serum pharmacokinetic (PK) studies were conducted utilizing anti-idiotypic antibodies in capture-ELISA assays. Hu2G10 (t1/2 = 6.5 days) and Hu2EF (t1/2 = 5.5 days) were stable in plasma, and were detectable in the circulation up to 3 weeks after the infusion. These findings validate primates as reliable models for Hu2G10 and Hu2EF toxicity and PK, and support the use of these antibodies as next-generation anti-Trop-2 immunotherapy tools.