Trop-2 protein overexpression is an independent marker for predicting disease recurrence in endometrioid endometrial carcinoma

The clinical landscape of antibody-drug conjugates in endometrial cancer

Clinical outcomes remain challenging in advanced or recurrent endometrial cancer due to tumor heterogeneity and therapy resistance. Antibody-drug conjugates are a novel class of cancer therapeutics, representing a promising treatment option for endometrial cancer. Antibody-drug conjugates consist of a high-affinity antibody linked to a cytotoxic payload through a stable linker. After binding to specific antigens on tumor cells, the drug is internalized, and the payload is released. In addition, the free intracellular drug may be released outside the target cell through a 'bystander effect' and kill neighboring cells, which is crucial in treating malignancies characterized by heterogeneous biomarker expression like endometrial cancer.This article aims to provide a comprehensive overview of the current clinical landscape of antibody-drug conjugates in the treatment of endometrial cancer. We conducted a thorough analysis of recent clinical trials focusing on efficacy, safety profiles, and the mechanisms by which antibody-drug conjugates target endometrial cancer. We focused particularly on the most promising antibody-drug conjugate targets in endometrial cancer under clinical investigation, such as human epidermal growth factor receptor 2 (HER2), folate receptor alpha (FRα), trophoblast cell-surface antigen-2 (TROP2), and B7-H4. We also briefly comment on the challenges, including the emergence of resistance mechanisms, and future development directions (especially agents targeting multiple antigens, combinatorial strategies, and sequential use of agents targeting the same antigen but using different payloads) in antibody-drug conjugate therapy for endometrial cancer.

Cis-regulatory control of transcriptional timing and noise in response to estrogen

Cis-regulatory elements control transcription levels, temporal dynamics, and cell-cell variation or transcriptional noise. However, the combination of regulatory features that control these different attributes is not fully understood. Here, we used single-cell RNA-seq during an estrogen treatment time course and machine learning to identify predictors of expression timing and noise. We found that genes with multiple active enhancers exhibit faster temporal responses. We verified this finding by showing that manipulation of enhancer activity changes the temporal response of estrogen target genes. Analysis of transcriptional noise uncovered a relationship between promoter and enhancer activity, with active promoters associated with low noise and active enhancers linked to high noise. Finally, we observed that co-expression across single cells is an emergent property associated with chromatin looping, timing, and noise. Overall, our results indicate a fundamental tradeoff between a gene's ability to quickly respond to incoming signals and maintain low variation across cells.

Cis-regulatory control of transcriptional timing and noise in response to estrogen

Cis-regulatory elements control transcription levels, temporal dynamics, and cell-cell variation or transcriptional noise. However, the combination of regulatory features that control these different attributes is not fully understood. Here, we used single cell RNA-seq during an estrogen treatment time course and machine learning to identify predictors of expression timing and noise. We find that genes with multiple active enhancers exhibit faster temporal responses. We verified this finding by showing that manipulation of enhancer activity changes the temporal response of estrogen target genes. Analysis of transcriptional noise uncovered a relationship between promoter and enhancer activity, with active promoters associated with low noise and active enhancers linked to high noise. Finally, we observed that co-expression across single cells is an emergent property associated with chromatin looping, timing, and noise. Overall, our results indicate a fundamental tradeoff between a gene's ability to quickly respond to incoming signals and maintain low variation across cells.

The Relationship between Trop-2, Chemotherapeutic Drugs, and Chemoresistance

Trop-2 is a highly conserved one-pass transmembrane mammalian glycoprotein that is normally expressed in tissues such as the lung, intestines, and kidney during embryonic development. It is overexpressed in many epithelial cancers but is absent in non-epithelial tumors. Trop-2 is an intracellular calcium signal transducer that participates in the promotion of cell proliferation, migration, invasion, metastasis, and probably stemness. It also has some tumor suppressor effects. The pro-tumoral actions have been thoroughly investigated and reported. However, Trop-2's activity in chemoresistance is less well known. We review a possible relationship between Trop-2, chemotherapy, and chemoresistance. We conclude that there is a clear role for Trop-2 in some specific chemoresistance events. On the other hand, there is no clear evidence for its participation in multidrug resistance through direct drug transport. The development of antibody conjugate drugs (ACD) centered on anti-Trop-2 monoclonal antibodies opened the gates for the treatment of some tumors resistant to classic chemotherapies. Advanced urothelial tumors and breast cancer were among the first malignancies for which these ACDs have been employed. However, there is a wide group of other tumors that may benefit from anti-Trop-2 therapy as soon as clinical trials are completed.

hIMB1636-MMAE, a Novel TROP2-Targeting Antibody-Drug Conjugate Exerting Potent Antitumor Efficacy in Pancreatic Cancer

Herein, we first prepared a novel anti-TROP2 antibody-drug conjugate (ADC) hIMB1636-MMAE using hIMB1636 antibody chemically coupled to monomethyl auristatin E (MMAE) via a Valine-Citrulline linker and then reported its characteristics and antitumor activity. With a DAR of 3.92, it binds specifically to both recombinant antigen (KD ∼ 0.687 nM) and cancer cells and could be internalized by target cells and selectively kill them with IC50 values at nanomolar/subnanomolar levels by inducing apoptosis and G2/M phase arrest. hIMB1636-MMAE also inhibited cell migration, induced ADCC effects, and had bystander effects. It displayed significant tumor-targeting ability and excellent tumor-suppressive effects in vivo, resulting in 5/8 tumor elimination at 12 mg/kg in the T3M4 xenograft model or complete tumor disappearance at 10 mg/kg in BxPc-3 xenografts in nude mice. Its half-life in mice was about 87 h. These data suggested that hIMB1636-MMAE was a promising candidate for the treatment of pancreatic cancer with TROP2 overexpression.

TROP2-directed nanobody-drug conjugate elicited potent antitumor effect in pancreatic cancer

BACKGROUND

Pancreatic cancer is a highly aggressive malignancy with limited treatment options and a poor prognosis. Trophoblast cell surface antigen 2 (TROP2), a cell surface antigen overexpressed in the tumors of more than half of pancreatic cancer patients, has been identified as a potential target for antibody-drug conjugates (ADCs). Almost all reported TROP2-targeted ADCs are of the IgG type and have been poorly studied in pancreatic cancer. Here, we aimed to develop a novel nanobody-drug conjugate (NDC) targeting TROP2 for the treatment of pancreatic cancer.

RESULTS

In this study, we developed a novel TROP2-targeted NDC, HuNbTROP2-HSA-MMAE, for the treatment of TROP2-positive pancreatic cancer. HuNbTROP2-HSA-MMAE is characterized by the use of nanobodies against TROP2 and human serum albumin (HSA) and has a drug-antibody ratio of 1. HuNbTROP2-HSA-MMAE exhibited specific binding to TROP2 and was internalized into tumor cells with high endocytosis efficiency within 5 h, followed by intracellular translocation to lysosomes and release of MMAE to induce cell apoptosis in TROP2-positive pancreatic cancer cells through the caspase-3/9 pathway. In a xenograft model of pancreatic cancer, doses of 0.2 mg/kg and 1 mg/kg HuNbTROP2-HSA-MMAE demonstrated significant antitumor effects, and a dose of 5 mg/kg even eradicated the tumor.

CONCLUSION

HuNbTROP2-HSA-MMAE has desirable affinity, internalization efficiency and antitumor activity. It holds significant promise as a potential therapeutic option for the treatment of TROP2-positive pancreatic cancer.

Prognostic significance of trophoblastic cell surface antigen 2 expression and pathologic parameters in patients with ampullary adenocarcinoma

Trophoblastic cell surface antigen 2 (TROP2) has been reported to be up-regulated in several types of carcinomas and is associated with aggressive behavior and poor survival. However, TROP2 expression and its clinical significance in ampullary adenocarcinoma (AA) have not been investigated. We examined TROP2 expression by immunohistochemistry in 112 patients with AAs. The associations of TROP2 expression with clinicopathologic characteristics were evaluated by χ2 analyses or Fisher's exact tests. The associations of TROP2 expression and pathologic parameters with survival were evaluated by the Kaplan-Meier method and univariate and multivariate Cox regression analyses. Eighty-six AAs (76.8%) were positive for TROP2, which showed a membranous and cytoplasmic staining. TROP2 expression was associated with higher frequency (P = .04) and higher number (P = .03) of lymph node metastasis, higher pN stage (P = .03), less frequent adenoma (P = .04), and higher frequency of recurrence/metastasis (P = .004). TROP2 expression was associated with shorter disease-free survival (P = .02) and overall survival (P = .03). TROP2 expression was an independent prognostic factor for disease-free survival (P = .04). We demonstrated that TROP2 was expressed in 76.8% of AAs. TROP2 expression was associated with higher frequency and high number of lymph node metastasis and higher pN stage. More importantly, TROP2 expression was associated with higher frequency of recurrence/metastasis, shorter disease-free and overall survival and was an independent prognostic factor for disease-free survival. Our results suggest that TROP2 may be used both as a prognostic marker and as a therapeutic target for patients with AAs.

Advancements in Systemic Therapy for Pancreatic Cancer

Outcomes for patients with advanced pancreatic cancer have improved in the past 12 years, mainly because of progress made in systemic therapies. New treatment strategies for advanced pancreatic cancer include switch maintenance with cytotoxic therapies, induction maintenance, and the utilization of targeted agents for patients with actionable variants, as well as ongoing development of cytotoxic regimens, such as NALIRIFOX. The activity of immunotherapy has been disappointing to date, but novel combinations and identifying appropriate patient populations may further unlock its potential.

Overview of Trop-2 in Cancer: From Pre-Clinical Studies to Future Directions in Clinical Settings

Trophoblast cell surface antigen-2 (Trop-2) is a glycoprotein that was first described as a membrane marker of trophoblast cells and was associated with regenerative abilities. Trop-2 overexpression was also described in several tumour types. Nevertheless, the therapeutic potential of Trop-2 was widely recognized and clinical studies with drug–antibody conjugates have been initiated in various cancer types. Recently, these efforts have been rewarded with the approval of sacituzumab govitecan from both the Food and Drug Administration (FDA) and European Medicines Agency (EMA), for metastatic triple-negative breast cancer patients. In our work, we briefly summarize the various characteristics of cancer cells overexpressing Trop-2, the pre-clinical activities of specific inhibitors, and the role of anti-Trop-2 therapy in current clinical practice. We also review the ongoing clinical trials to provide a snapshot of the future developments of these therapies.

A literature review of the promising future of TROP2: a potential drug therapy target

Background and Objective

Previous studies have demonstrated that the oncogene trophoblast cell surface antigen 2 (TROP2) has great application prospects as a therapeutic target. However, few literature reviews have systematically summarized and evaluated its role in cancer therapy. This study aims to summarize the molecular structure, functions, signal transduction pathways, and prognostic value of TROP2, and explore therapeutic agents that target TROP2.

Methods

A total of 1,376 published literatures from PubMed and 614 published literatures from EMBASE were retrieved by searching "TROP2" or "Trophoblast cell surface antigen 2". The search was conducted on December 12, 2020, and updated on November 20, 2022. The cBioportal and GEPIA (Gene Expression Profiling Interactive Analysis) databases were used to analyze the expression, mutation, and prognostic value of TROP2 in different types of cancer.

Key Content and Findings

TROP2 is overexpressed in different tumor tissues and plays roles in cell proliferation, invasion, migration, apoptosis, and treatment resistance by binding to or interacting with several molecules. As a therapeutic target, TROP2 is particularly suitable for antibody-based therapies. Monoclonal antibodies, bispecific antibodies, antibody-drug conjugates (ADCs), virus-like particles, and antibody drugs in combination with traditional chemotherapy, immunotherapy, radioimmunotherapy, photoimmunotherapy, and nanoparticles that target TROP2 have thus far been rapidly developed. For example, sacituzumab govitecan (IMMU-132), a TROP2-targeting ADC, was granted accelerated approval for the treatment of metastatic triple-negative breast cancer (TNBC). Anti-TROP2 antibody-conjugated nanoparticles (ST-NPs) are a promising vehicle for delivering doxorubicin in targeted TNBC therapy.

Conclusions

The availability of TROP2-targeting ADCs makes TROP2 an accessible and promising therapeutic target for advanced metastatic cancers. The present review describes the important role of TROP2 in tumorigenesis and its potential applications as a promising biomarker and therapeutic target that is capable of reversing resistance.

Advances in Trop2-targeted therapy: Novel agents and opportunities beyond breast cancer

Trop2 is a transmembrane glycoprotein and calcium signal transducer with limited expression in normal human tissues. It is consistently overexpressed in a variety of malignant tumors and participates in several oncogenic signaling pathways that lead to tumor development, invasion, and metastasis. As a result, Trop2 has become an attractive therapeutic target in cancer treatment. The anti-Trop2 antibody-drug conjugate (Trodelvy™, sacituzumab govitecan) has been approved to treat metastatic triple-negative breast cancer. However, it is still unclear whether the success observed in Trop2-positive breast cancer could be replicated in other tumor types, owing to the differences in the expression levels and functions of Trop2 across cancer types. In this review, we summarize the recent progress on the structures and functions of Trop2 and highlight the potential diagnostic and therapeutic value of Trop2 beyond breast cancer. In addition, the promising novel Trop2-targeted agents in the clinic were discussed, which will likely alter the therapeutic landscape of Trop2-positive tumors in the future.

TROP2 (trophoblast cell-surface antigen 2): a drug target for breast cancer

INTRODUCTION

Breast cancer (BC) is the most common diagnosed cancer and the second leading cause of cancer-associated death in women, with the triple negative (TNBC) subtype being characterized by the poorest prognosis. New therapeutic targets are urgently needed to overcome the high metastatic potential, aggressiveness and poor survival of these tumors. Trop2 transmembrane glycoprotein, acting as an intracellular calcium signal transducer, recently emerged as a new potential target in epithelial cancers, in particular in breast cancer.

AREAS COVERED

We summarize the key features of Trop2 structure and function, describing the therapeutic strategies targeting this protein in cancer. Particular attention is paid to antibody-drug conjugates (ADCs), actually representing the most successful strategy.

EXPERT OPINION

ADCs targeting Trop2 recently received an accelerated FDA approval for the therapy of metastatic TNBC. The prospects for these novel ADCs in BC subtypes other than TNBC are discussed, taking into account the main pitfalls relative to Trop2 structure and function.

Research Trend of Publications Concerning Antibody-Drug Conjugate in Solid Cancer: A Bibliometric Study

Background: Antibody-drug conjugate (ADC) is a promising therapy for solid cancer that has raised global concern. Although several papers have reviewed the current state of ADCs in different solid cancers, a quantitative analysis of the publications in this field is scarce.

Methods: Publications related to ADC in the field of solid cancer were obtained from the Web of Science Core Collection. Data analyses were performed with VOSviewer 1.6.9, HistCite 2.1, CiteSpace V and R package Bibliometrix.

Results: A total of 3,482 records were obtained in the holistic field and 1,197 in the clinical field. Steady growth in the number of publications was observed. The United States was the leading contributor in this field. Krop IE was the most influential author. The most productive institution was Genentech Inc., while Mem Sloan Kettering Canc Ctr was the most cited one. The most impactful journal was the Journal of Clinical Oncology. A total of 37 burst references and five burst references were identified between 2017–2022 in the holistic and clinical fields, respectively. Keywords analysis indicated that ADCs research mainly involved breast cancer, triple-negative breast cancer, ovarian cancer, small cell lung cancer, prostate cancer, gastric cancer, and urothelial carcinoma. ADC agents including trastuzumab emtansine, trastuzumab deruxtecan, sacituzumab govitecan, enfortumab vedotin, and rovalpituzumab tesirine were highly studied. Targets including HER2, trophoblast cell-surface antigen, mesothelin, delta-like ligand 3, and nectin-4 were the major concerns.

Conclusion: This study analyzed publications concerning ADCs in the field of solid cancer with bibliometric analysis. Further clinical trials of ADCs and designs of the next generation of ADCs are the current focuses of the field. Acquired resistance of ADCs and biomarkers for ADC therapy efficacy monitoring are future concerns.

Advancing antibody-drug conjugates in gynecological malignancies: myth or reality?

Antibody-drug conjugates (ADCs) represent a new class of therapeutic agents designed to target specific antigens on tumor cells, combining the specificity of monoclonal antibodies to the cytotoxicity of classic chemotherapy agents. These drugs have been extensively studied both in solid and hematologic malignancies, leading to substantial improvement in the therapeutic landscape for several tumors. Despite no ADC have been yet approved for the treatment of gynecological malignancies, some agents have shown promising results and might have the potential to become part of the standard of care. Among them, mirvetuximab soravtansine has shown activity in platinum-resistant ovarian cancer with high folate-α receptor expression, as a single agent and in combination. Tisotumab vedotin is active in patients with pre-treated cervical cancer, and further investigation is ongoing. The purpose of this review is to summarize the structural and functional characteristics of ADCs and analyze the most recent and promising data regarding the clinical development of ADCs in gynecological malignancies. The available data on the efficacy of the more studied ADCs in ovarian, endometrial, and cervical cancers will be discussed along with toxicities of special interest, the mechanisms of resistance, and future possible drugs combination.

Recent advances in trophoblast cell-surface antigen 2 targeted therapy for solid tumors

Trophoblast cell-surface antigen 2 (Trop 2) is a transmembrane glycoprotein that is highly expressed in various cancer types with relatively low or no baseline expression in most normal tissues. Its overexpression is associated with tumor growth and poor prognosis; Trop 2 is, therefore, an ideal therapeutic target for epithelial cancers. Several Trop 2 targeted therapeutics have recently been developed for the treatment of cancers, such as anti-Trop 2 antibodies and antibody-drug conjugates (ADCs), as well as Trop 2-specific cell therapy. In particular, the safety and clinical benefit of Trop 2-based ADCs have been demonstrated in clinical trials across multiple tumor types, including those with limited treatment options, such as triple-negative breast cancer, platinum-resistant urothelial cancer, and heavily pretreated non-small cell lung cancer. In this review, we elaborate on recent advances in Trop 2 targeted modalities and provide an overview of novel insights for future developments in this field.

Can TROP2 be used as a prognostic marker in endometrioid endometrial carcinoma?

Background

Endometrioid-type endometrial carcinoma is the most common malignancy of the female genital tract in developed countries. The prognosis greatly depends on the grade and stage of the disease.

Aims

In some patients, the disease recurs in a short time after the surgical/medical therapy. Hence, it is important to predict the patients who will have worse prognosis at the beginning, to choose the appropriate treatment; resuming the search of new prognostic markers. Therefore, our study aimed to detect trophoblast cell surface antigen 2 (TROP2) as a new prognostic marker.

Settings and Design

The patients who underwent a hysterectomy and diagnosed with endometrioid-type endometrial carcinoma were evaluated retrospectively and TROP2 immunostain was performed to their tumoral slides.

Materials and Methods

We evaluated TROP2 expressions in 102 patients immunohistochemically who underwent hysterectomy with the diagnosis of endometrioid-type endometrial carcinoma histopathologically and correlated them with the other generally accepted prognostic parameters.

Statistical Analysis

The Kolmogorov-Smirnov test and Q-Q plot test were used to verify the normality of the distribution of continuous variables. The Chi-square/Fisher's exact tests were used for categorical variables. Analyses were performed with SPSS Statistics for Windows, Version 20.

Results

High overexpression of TROP2 was seen in larger, higher-grade, deeper-invasive tumors, tumors with vascular invasion, and pelvic-lymph-node metastasis. These results were statistically significant (P ≤ 0.05).

Conclusion

Overexpression of TROP2 in endometrioid-type endometrial carcinoma seems to be a poor prognostic factor; it may be useful in determining the biologically more aggressive tumors before the treatment. This early determination is very important to choose the appropriate surgery, adjuvant-treatments, and follow-up.

Characterizing the Invasive Tumor Front of Aggressive Uterine Adenocarcinoma and Leiomyosarcoma

The invasive tumor front (the tumor–host interface) is vitally important in malignant cell progression and metastasis. Tumor cell interactions with resident and infiltrating host cells and with the surrounding extracellular matrix and secreted factors ultimately determine the fate of the tumor. Herein we focus on the invasive tumor front, making an in-depth characterization of reticular fiber scaffolding, infiltrating immune cells, gene expression, and epigenetic profiles of classified aggressive primary uterine adenocarcinomas (24 patients) and leiomyosarcomas (11 patients). Sections of formalin-fixed samples before and after microdissection were scanned and studied. Reticular fiber architecture and immune cell infiltration were analyzed by automatized algorithms in colocalized regions of interest. Despite morphometric resemblance between reticular fibers and high presence of macrophages, we found some variance in other immune cell populations and distinctive gene expression and cell adhesion-related methylation signatures. Although no evident overall differences in immune response were detected at the gene expression and methylation level, impaired antimicrobial humoral response might be involved in uterine leiomyosarcoma spread. Similarities found at the invasive tumor front of uterine adenocarcinomas and leiomyosarcomas could facilitate the use of common biomarkers and therapies. Furthermore, molecular and architectural characterization of the invasive front of uterine malignancies may provide additional prognostic information beyond established prognostic factors.

Treating Bladder Cancer: Engineering of Current and Next Generation Antibody-, Fusion Protein-, mRNA-, Cell- and Viral-Based Therapeutics

Bladder cancer is a frequent malignancy and has a clinical need for new therapeutic approaches. Antibody and protein technologies came a long way in recent years and new engineering approaches were applied to generate innovative therapeutic entities with novel mechanisms of action. Furthermore, mRNA-based pharmaceuticals recently reached the market and CAR-T cells and viral-based gene therapy remain a major focus of biomedical research. This review focuses on the engineering of biologics, particularly therapeutic antibodies and their application in preclinical development and clinical trials, as well as approved monoclonal antibodies for the treatment of bladder cancer. Besides, newly emerging entities in the realm of bladder cancer like mRNA, gene therapy or cell-based therapeutics are discussed and evaluated. As many discussed molecules exhibit unique mechanisms of action based on innovative protein engineering, they reflect the next generation of cancer drugs. This review will shed light on the engineering strategies applied to develop these next generation treatments and provides deeper insights into their preclinical profiles, clinical stages, and ongoing trials. Furthermore, the distribution and expression of the targeted antigens and the intended mechanisms of action are elucidated.

Sacituzumab govitecan, a Trop-2-directed antibody-drug conjugate, for patients with epithelial cancer: final safety and efficacy results from the phase I/II IMMU-132-01 basket trial

BACKGROUND

Sacituzumab govitecan (SG), a trophoblast cell surface antigen-2 (Trop-2)-directed antibody-drug conjugate, has demonstrated antitumor efficacy and acceptable tolerability in a phase I/II multicenter trial (NCT01631552) in patients with advanced epithelial cancers. This report summarizes the safety data from the overall safety population (OSP) and efficacy data, including additional disease cohorts not published previously.

PATIENTS AND METHODS

Patients with refractory metastatic epithelial cancers received intravenous SG (8, 10, 12, or 18 mg/kg) on days 1 and 8 of 21-day cycles until disease progression or unacceptable toxicity. Endpoints for the OSP included safety and pharmacokinetic parameters with investigator-evaluated objective response rate (ORR per RECIST 1.1), duration of response, clinical benefit rate, progression-free survival, and overall survival evaluated for cohorts (n > 10 patients) of small-cell lung, colorectal, esophageal, endometrial, pancreatic ductal adenocarcinoma, and castrate-resistant prostate cancer.

RESULTS

In the OSP (n = 495, median age 61 years, 68% female; UGT1A1∗28 homozygous, n = 46; 9.3%), 41 (8.3%) permanently discontinued treatment due to adverse events (AEs). Most common treatment-related AEs were nausea (62.6%), diarrhea (56.2%), fatigue (48.3%), alopecia (40.4%), and neutropenia (57.8%). Most common treatment-related serious AEs (n = 75; 15.2%) were febrile neutropenia (4.0%) and diarrhea (2.8%). Grade ≥3 neutropenia and febrile neutropenia occurred in 42.4% and 5.3% of patients, respectively. Neutropenia (all grades) was numerically more frequent in UGT1A1∗28 homozygotes (28/46; 60.9%) than heterozygotes (69/180; 38.3%) or UGT1A1∗1 wild type (59/177; 33.3%). There was one treatment-related death due to an AE of aspiration pneumonia. Partial responses were seen in endometrial cancer (4/18, 22.2% ORR) and small-cell lung cancer (11/62, 17.7% ORR), and one castrate-resistant prostate cancer patient had a complete response (n = 1/11; 9.1% ORR).

CONCLUSIONS

SG demonstrated a toxicity profile consistent with previous published reports. Efficacy was seen in several cancer cohorts, which validates Trop-2 as a broad target in solid tumors.

Trophoblast cell surface antigen 2 expression predicts outcome in oral squamous cell carcinomas

BACKGROUND

Trophoblast cell surface antigen 2 (TROP2) has unclear clinical role in oral squamous cell carcinomas (OSCC). Here, we investigated the association of TROP2 immunoexpression with clinicopathological parameters and survival of OSCC patients.

SUBJECTS AND METHODS

Cancer-specific survival (CSS) and disease-free survival (DFS) were assessed in a cohort composed of 266 OSCC. An independent cohort with 88 OSCC samples matched with the normal oral tissue, as well as 17 metastatic lymph nodes, was used for validation.

RESULTS

Multivariate analysis showed TROP2 as an independent marker of favorable prognosis for both CSS (HR: 0.60, 95% CI: 0.40-0.90, p = .01) and DFS (HR: 0.57, 95% CI: 0.36-0.89, p = .01). Furthermore, TROP2 protein expression was significantly higher in morphologically normal tissues compared to primary tumors (p < .0001) and lymph node metastases (p = .001), and it was significantly associated with CSS (HR: 0.26, 95% CI: 0.09-0.74, p = .008) in the validation cohort. A pooled mRNA analysis performed on the Oncomine™ database confirmed the underexpression in OSCC compared with normal tissues (p = .014).

CONCLUSIONS

In summary, our results point to a favorable prognostic significance of TROP2 overexpression in a large cohort of oral cancer patients, suggesting it as an attractive clinical marker.

Could trop-2 overexpression indicate tumor aggressiveness among prostatic adenocarcinomas?

BACKGROUND

TROP-2, a novel marker of trophoblastic cells, is being widely analyzed for its possible role in carcinogenesis and clinical behavior of various carcinomas. In this study, we aimed to evaluate the relationship between clinicopathologic parameters and TROP2 expression in prostatic adenocarcinomas.

METHODS

101 prostatic adenocarcinomas treated by radical prostatectomy in our hospital between 2013 and 2018 were reviewed retrospectively for histopathological features, and one representative block of each case was stained with TROP2 antibody. Histopathologic prognostic features were assessed for their relationship with TROP2 expression.

RESULTS

The mean age was found as 64.11 year. TROP2 was stained in over 10% of the tumoral cells in 64 (63.4.%) cases. Gleason grade group, perineural invasion, lymphovascular invasion, ganglionic and seminal vesicle involvement, lateral and basal surgical margin positivity showed a significant relationship with TROP2 staining.

CONCLUSION

TROP2 is overexpressed in various human cancers and TROP2 overexpression appears to correlate with poor prognosis leading to the suggestion that TROP2 could be a therapeutic target for various carcinomas. Our results suggest that TROP2 expression is higher in advanced tumors and these results need to be supported by larger studies.

Trop2: Jack of All Trades, Master of None

Trophoblast cell surface antigen 2 (Trop2) is a widely expressed glycoprotein and an epithelial cell adhesion molecule (EpCAM) family member. Although initially identified as a transmembrane protein, other subcellular localizations and processed forms were described. Its congenital mutations cause a gelatinous drop-like corneal dystrophy, a disease characterized by loss of barrier function in corneal epithelial cells. Trop2 is considered a stem cell marker and its expression associates with regenerative capacity in various tissues. Trop2 overexpression was described in tumors of different origins; however, functional studies revealed both oncogenic and tumor suppressor roles. Nevertheless, therapeutic potential of Trop2 was recognized and clinical studies with drug-antibody conjugates have been initiated in various cancer types. One of these agents, sacituzumab govitecan, has been recently granted an accelerated approval for therapy of metastatic triple-negative breast cancer. In this article, we review the current knowledge about the yet controversial function of Trop2 in homeostasis and pathology.

Sacituzumab govitecan, a novel, third-generation, antibody-drug conjugate (ADC) for cancer therapy

INTRODUCTION

We describe a new, third-generation of antibody-drug conjugates (ADCs) having a high drug payload against topoisomerase I, important for DNA function, and targeting selective tumor antigens, predominantly TROP-2.

AREAS COVERED

The historical development of ADCs is reviewed before presenting the current line of improved, third-generation ADCs targeting topoisomerase I, thus affecting DNA and causing double-stranded DNA breaks. Emphasis is given to explaining why sacituzumab govitecan represents a paradigm change in ADCs by achieving a high therapeutic index due to its novel target, TROP-2, an internalizing antigen/antibody, proprietary linker chemistry, and high drug payload, resulting in a high tumor concentration of the drug given in repeated doses with acceptable tolerability, particularly evidencing a lower percentage of 'late' diarrhea than its prodrug, irinotecan. PubMed was used for the primary search conducted.

EXPERT OPINION

The properties and clinical results of third-generation ADCs, based on sacituzumab govitecan, are discussed, including prospects for future applications, particularly combination therapies with PARP inhibitors and immune checkpoint inhibitors. Since one topoisomerase I ADC has just received regulatory approval for HER2⁺ breast cancer, and sacituzumab govitecan is under FDA review for accelerated approval in the therapy of triple-negative breast cancer, the prospects for these novel ADCs are discussed.

Sacituzumab govitecan, an antibody-drug conjugate targeting trophoblast cell-surface antigen 2, shows cytotoxic activity against poorly differentiated endometrial adenocarcinomas in vitro and in vivo

Endometrial cancer is the most common gynecologic malignancy in developed countries. The antibody-drug conjugate (ADC) sacituzumab govitecan (SG) targets trophoblast cell-surface antigen-2 (Trop-2) - a cell-surface glycoprotein highly expressed in many epithelial tumors - and delivers the active metabolite of irinotecan SN-38 to Trop-2-positive tumor cells. We evaluated Trop-2 expression in endometrial endometrioid carcinoma (EC) tissues and the activity of SG against primary poorly differentiated EC cell lines and xenografts. Trop-2 expression was assessed in 143 formalin-fixed-paraffin-embedded tumors and seven primary tumor cell lines by immunohistochemistry and flow cytometry, respectively. Cell viability of primary tumor cell lines was assessed following exposure to SG, or control antibodies. Antibody-dependent cell cytotoxicity (ADCC) against Trop-2-positive and Trop-2-negative EC cell lines was measured in vitro using 4-h chromium release assays. A Trop-2-positive EC xenograft model was used to determine the in vivo activity of SG. Moderate-to-strong staining was detected in 84% (120/143) of EC samples, whereas 43% (3/7) of the primary EC cell lines tested overexpressed Trop-2. EC cell lines overexpressing Trop-2 were significantly more sensitive to SG compared to control ADC (P = 0.014 and P = 0.005). Both SG and the unconjugated parental antibody hRS7 mediated high ADCC against Trop-2-positive cell lines. Moreover, SG induced significant bystander killing of Trop-2-negative tumors cocultured with Trop-2-positive tumors. In the xenograft model, intravenous administration of SG twice weekly for three weeks was well tolerated and demonstrated impressive tumor growth inhibition against poorly differentiated, chemotherapy-resistant EC xenografts (P = 0.011). In summary, SG is a novel ADC with remarkable preclinical activity against poorly differentiated EC cell lines overexpressing Trop-2. These findings warrant future clinical trials.

Preclinical activity of sacituzumab govitecan (IMMU-132) in uterine and ovarian carcinosarcomas

Background

Uterine and ovarian carcinosarcomas (CS) are rare cancers with poor prognosis. Sacituzumab-govitecan (SG) is a new class of antibody-drug-conjugate (ADC) targeting the human-trophoblast-cell-surface marker (Trop-2) conjugated with the active metabolite of irinotecan (SN-38). We evaluated the efficacy of SG against biologically aggressive CS.

Methods

Trop-2 expression was evaluated in 10 formalin-fixed-paraffined-embedded (FFPE) CS by immunohistochemistry and 9 primary CS cell-lines by flow-cytometry. One Trop-2 low/negative (SARARK14) and two Trop-2 positive (SARARK4, SARARK9) cell-lines were tested in cell-viability assays . The in vivo antitumor activity of SG was tested in xenografts models (ie, SARARK9) with strong Trop-2 expression.

Results

Strong/diffuse staining was seen in 30% (3/10) of FFPE tumors and 33% (3/9) of primary CS cell lines. Trop-2 positive cell-lines (SARARK4, SARARK9) showed higher sensitivity to SG in vitro when compared to Trop-2 low/negative (SARARK14) cell lines. In xenografts, twice-weekly intravenous administration of SG for three weeks showed a significant tumor growth inhibition when compared to control, to ADC control and to the naked AB (p=0.004, p=0.007 and p=0.0007, respectively). SG significantly improved overall survival at 90 days when compared to control groups (p<0.0001).

Conclusion

SG may represent a novel class of active drugs for carcinosarcomas patients overexpressing Trop-2.

Knockdown of Trop2 inhibits proliferation and migration and induces apoptosis of endometrial cancer cells via AKT/β-catenin pathway

Endometrial cancer (EC) is the most common gynaecologic malignancy in western countries and has been reported to account for about 7% of female malignant tumours and 20% to 30% of female genital system malignant tumours. Accumulating evidence showed the expression of human trophoblast cell surface antigen 2 (Trop2) was abnormal in many cancers; however, the expression and role of Trop2 in EC are not clear. The Trop-2 protein expression was detected by western blot in EC cells. Cell proliferation, apoptosis, and migration were measured by CCK-8, flow cytometry, and Transwell assay, respectively. The epithelial mesenchymal transition (EMT) and AKT/β-catenin signalling pathway-related proteins in EC cell lines were detected by western blot assay following Trop2 gene silencing. The present study revealed that the Trop2 protein was highly expressed in EC cell lines compared with human endometrial epithelial cells. The Trop2 mRNA and protein were obviously decreased following transfection with Trop2-siRNA sequence in KLE and Ishikawa cells. Meanwhile, Trop2 gene silencing in KLE and Ishikawa cells strongly inhibited cell proliferation and migration and increased cell apoptosis. Investigation into the molecular mechanism indicated that the Trop2 gene silencing suppressed EMT and AKT/β-catenin signalling pathway activation. SIGNIFICANCE OF THE STUDY: These findings suggested that Trop2 silencing inhibited EC cell proliferation and migration and promoted cell apoptosis. The mechanism might be related to the inhibition of the AKT/β-catenin signalling pathway in EC cells. Therefore, Trop2 may be a potential therapeutic target for the treatment of EC.

In vitro and in vivo activity of sacituzumab govitecan, an antibody-drug conjugate targeting trophoblast cell-surface antigen 2 (Trop-2) in uterine serous carcinoma

OBJECTIVE

Uterine serous carcinoma (USC) is an aggressive variant of endometrial cancer with poor prognosis. Sacituzumab govitecan (SG) is a novel antibody-drug-conjugate (ADC) targeting trophoblast cell-surface antigen 2 (Trop-2), a transmembrane-calcium-signal-transducer, to deliver SN-38, the active metabolite of irinotecan. The objective of this study was to evaluate the expression of Trop-2 in USC and the preclinical activity of SG against primary USC cell-lines and xenografts.

METHODS

We used immunohistochemistry (IHC) and flow-cytometry-based assays to evaluate Trop-2 expression and cell-viability in USC tissue and primary tumor-cell-lines after exposure to SG, non-targeting control ADC, and naked antibody hRS7-IgG. Antibody-dependent-cell-cytotoxicity (ADCC) against Trop-2+ and Trop-2- USC cell-lines was evaluated in vitro using 4-hr-Chromium-release-assays. In vivo activity of SG was tested against Trop-2+ USC xenografts by intravenous administration of SG, control ADC, and hRS7.

RESULTS

Trop-2 expression by IHC was detected in 95.1% of USC samples (99/104). Primary tumor cell-lines overexpressing Trop-2 were significantly more sensitive to SG when compared to control ADC (p <0.05). Both SG and hRS7 mediated ADCC in Trop2+ USC cell-lines while no cytotoxicity was detected against Trop-2- cells. SG induced significant bystander killing of Trop-2- tumors when admixed with Trop-2+ tumors. SG caused growth-inhibition and increased survival in SG treated mice harboring Trop-2+ xenografts when compared to controls (p <0.05).

CONCLUSIONS

SG is remarkably active against USC overexpressing Trop-2 in vitro and in vivo. Our results combined with SG clinical responses recently reported against multiple chemotherapy resistant human tumors further support clinical development of SG in USC patients with advanced/recurrent disease.

Variation of Trop2 on non-small-cell lung cancer and normal cell membranes revealed by super-resolution fluorescence imaging

Transmembrane glycoprotein Trop2 is related to many epithelial carcinomas. It not only plays roles in promoting fetal lung growth but also participates in tumor genesis, malignant transformation, and tumor dissemination. However, the detailed distribution of Trop2 at the molecular level remains unknown. Herein, we used direct stochastic optical reconstruction microscopy to reveal the spatial organization of Trop2 on the membranes of cultured and primary lung cancer cells and normal cells. All types of cancer cells presented more localizations of Trop2 than normal cells. By SR-Teseller cluster analysis, we found that Trop2 existed in the form of clusters on all the membranes; however, cancer cells generated more and larger clusters consisting of more molecules than normal cells. Our findings shed light on the heterogeneous distribution of membrane Trop2 and highlighted the significant differences of its clustering characteristics between lung cancer cells and normal cells, which laid the basis for further studying the mechanism and functions of Trop2 clustering in lung cancer.

TROP-2 exhibits tumor suppressive functions in cervical cancer by dual inhibition of IGF-1R and ALK signaling

OBJECTIVE

Inactivation of tumor suppressor genes promotes initiation and progression of cervical cancer. This study aims to investigate the tumor suppressive effects of TROP-2 in cervical cancer cells and to explain the underlying mechanisms.

METHODS

The tumor suppressive functions of TROP-2 in cervical cancer cells were examined by in vitro and in vivo tumorigenic functional assays. Downstream factors of TROP-2 were screened using Human Phospho-Receptor Tyrosine Kinase Array. Small molecule inhibitors were applied to HeLa cells to test the TROP-2 effects on the oncogenicity of IGF-1R and ALK. Protein interactions between TROP-2 and the ligands of IGF-1R and ALK were detected via immunoprecipitation assay and protein-protein affinity prediction.

RESULTS

In vitro and in vivo functional assays showed that overexpression of TROP-2 significantly inhibited the oncogenicity of cervical cancer cells; while knockdown of TROP-2 exhibited opposite effects. Human Phospho-Receptor Tyrosine Kinase Array showed that the activity of IGF-1R and ALK was stimulated by TROP-2 knockdown. Small molecule inhibitors AG1024 targeting IGF-1R and Crizotinib targeting ALK were treated to HeLa cells with and without TROP-2 overexpression, and results from cell viability and migration assays indicated that the oncogenicity of vector-transfected cells was repressed to a greater extent by the inhibition of either IGF-1R or ALK than that of the TROP-2-overexpressed cells. Immunoprecipitation assay and protein-protein affinity prediction suggested protein interactions between TROP-2 and the ligands of IGF-1R and ALK.

CONCLUSIONS

Collectively, our results support that TROP-2 exhibits tumor suppressor functions in cervical cancer through inhibiting the activity of IGF-1R and ALK.

High expression of TROP2 is correlated with poor prognosis of oral squamous cell carcinoma

Human trophoblastic cell-surface antigen 2 (TROP2) is a cell surface glycoprotein that exhibits high expression in various carcinomas but low or no expression in normal tissues. High TROP2 expression plays an important role in promoting tumor development and aggressiveness, which is correlated with reduced patient survival. However, there are few studies regarding TROP2 in relation to both oral squamous cell carcinoma (OSCC) and oral potentially malignant lesions. The expression of TROP2 protein and mRNA was investigated in OSCC tissues, oral potentially malignant lesion tissues, and normal oral tissues using immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). The association between TROP2 expression and clinicopathological characteristics of OSCC was also analyzed, and the prognostic value of TROP2 was evaluated. The expression of TROP2 protein and mRNA were both higher in OSCC tissues than in oral potentially malignant lesion tissues or normal oral tissues. Positive TROP2 expression was related to differentiation, lymph node metastases, TNM stage, perineural infiltration, and vascular invasion. Poor overall survival was associated with high TROP2 expression and other factors associated with poor overall survival including poor differentiation, lymph node metastasis, TNM stage, vascular invasion, and perineural invasion in univariate analyses. TROP2 expression as well as TNM stage and vascular invasion were independent prognostic factors associated with the overall survival of OSCC patients in multivariate analyses. In summary, High TROP2 expression is associated with poor overall survival and serves as an independent prognostic factor in OSCC. The results suggest that TROP2 expression could be an effective prognostic biomarker for OSCC.

Sacituzumab Govitecan (IMMU-132) in treatment-resistant uterine serous carcinoma: A case report

Background

Uterine serous carcinoma (USC) is a biologically aggressive variant of uterine cancer. Effective treatment options for recurrent, chemotherapy-resistant USC are extremely limited.

Case

We describe a 74-year-old woman with recurrent and widespread treatment-resistant disease, who experienced a dramatic response to sacituzumab govitecan, a novel antibody-drug conjugate (ADC) targeting human trophoblast-cell-surface antigen (TROP-2), after failing multiple chemotherapy and immunotherapy. The impressive clinical response (66% reduction of target lesions by RECIST 1.1 with a duration response of over 10 months) was confirmed with serial CT scans in the absence of significant adverse events.

Conclusion

Sacituzumab govitecan may present a new treatment option for recurrent USC patients harboring Trop-2+ tumors resistant to chemotherapy. Clinical trials with sacituzumab govitecan are warranted.

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Uterine serous carcinoma (USC) is a rare but aggressive variant of uterine cancer.

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Sacituzumab-govitecan (IMMU-132) is an antibody-drug conjugate targeting TROP-2.

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IMMU-132 may represent a new treatment option for USC overexpressing TROP-2.

The Potential Diagnostic Utility of TROP-2 in Thyroid Neoplasms

Objectives:

Human trophoblast cell-surface marker (TROP-2) has been reported to be overexpressed in various human carcinomas (CAs) and suggested to be a prognostic marker for some CAs. The diagnostic utility of TROP-2 in CAs has not been explored.

Methods:

Immunohistochemical evaluation of TROP-2 expression on tissue microarray sections of 136 thyroid neoplasms, surgical specimens of 61 atypical thyroid follicular-patterned lesions [including 33 papillary thyroid carcinomas (PTCs), 17 atypical follicular neoplasms (AFNs), and 11 adenomatoid nodules with focal nuclear atypia (ANFNA)], and 20 benign thyroid lesions, as well as 10 cytology specimens of PTCs was performed. For comparison, immunoassay for Hector Battifora mesothelial-1 (HBME-1), galectin-3, and cytokeratin 19 was performed on the 61 atypical thyroid follicular-patterned lesions.

Results:

Strong membranous staining with TROP-2 was seen in 94% (33/35) of classic PTCs and 81% (30/37) of confirmed follicular variant PTCs on tissue microarray and routine surgical sections, as well as 100% (10/10) of PTCs on cytology specimens; it was not observed in follicular adenomas (n=51) or CAs (n=37), AFNs or ANFNA (n=28), benign (n=20) or normal (n=15) thyroid tissue. In contrast, the expression of HBME-1 and galectin-3 was identified in 100% (33/33) of surgical cases of PTCs and in 57% (16/28) and 50% (14/28) of AFNs and ANFNA, respectively.

Conclusions:

Our findings demonstrate that a membranous TROP-2 staining pattern is highly specific for PTC, which may serve as a potential diagnostic marker aiding in the accurate classification of morphologically equivocal thyroid follicular-patterned lesions.

Incorporation of CD40 ligand enhances the immunogenicity of tumor‑associated calcium signal transducer 2 virus‑like particles against lung cancer

The cell surface glycoprotein Trop‑2 is overexpressed in various types of cancer, including in lung cancer, and has recently been used as an effective immunotherapeutic target. CD40 ligand (CD40L), a tumor necrosis factor superfamily member, is a promising immune adjuvant. Human immunodeficiency virus (HIV) gag‑based virus‑like particles (VLPs) are highly immunogenic, and foreign antigens can be incorporated onto their membrane envelope for cancer vaccine development. In the present study, a HIV gag‑based VLP strategy and Bac‑to‑Bac system were utilized to construct Trop‑2, CD40L and gag recombinant baculoviruses, which were then used to infect TN5 cells in order to form Trop‑2 VLPs or Trop‑2‑CD40L VLPs. These VLPs were characterized using transmission electron microscopy and western blot analysis methods. VLPs incorporating murine Trop‑2 only or incorporating Trop‑2 and CD40L were used to immunize C57BL/6 mice. Immunized mice demonstrated high humoral and cellular immunity responses, whereas the Trop‑2‑CD40L VLPs led to higher immune responses in comparison with Trop‑2 only VLPs. Immunization with Trop‑2‑CD40L VLPs also reduced tumor growth more effectively compared with Trop‑2 VLPs. Furthermore, Trop‑2‑CD40L VLP immunization increased the survival rate of Lewis tumor‑bearing mice more significantly when compared with Trop‑2 only VLPs. In conclusion, the present study provided a novel vaccine design by combination of a tumor antigen and an immune adjuvant based on a VLP strategy, which may be potentially applied as an alternative immunotherapeutic option in the treatment of lung cancer.

A phase 1, dose-escalation study of PF-06664178, an anti-Trop-2/Aur0101 antibody-drug conjugate in patients with advanced or metastatic solid tumors

Purpose and Methods Trop-2 is a glycoprotein over-expressed in many solid tumors but at low levels in normal human tissue, providing a potential therapeutic target. We conducted a phase 1 dose-finding study of PF-06664178, an antibody-drug conjugate that targets Trop-2 for the selective delivery of the cytotoxic payload Aur0101. The primary objective was to determine the maximum tolerated dose and recommended phase 2 dose. Secondary objectives included further characterization of the safety profile, pharmacokinetics and antitumor activity. Eligible patients were enrolled and received multiple escalating doses of PF-06664178 in an open-label and unblinded manner based on a modified continual reassessment method. Results Thirty-one patients with advanced or metastatic solid tumors were treated with escalating doses of PF-06664178 given intravenously every 21 days. Doses explored ranged from 0.15 mg/kg to 4.8 mg/kg. Seven patients experienced at least one dose limiting toxicity (DLT), either neutropenia or rash. Doses of 3.60 mg/kg, 4.2 mg/kg and 4.8 mg/kg were considered intolerable due to DLTs in skin rash, mucosa and neutropenia. Best overall response was stable disease in 11 patients (37.9%). None of the patients had a partial or complete response. Systemic exposure of PF-06664178 increased in a dose-related manner. Serum concentrations of free Aur0101 were substantially lower than those of PF-06664178 and total antibody. No correlation of Trop-2 expression and objective response was observed, although Trop-2 overexpression was not required for study entry. The intermediate dose of 2.4 mg/kg appeared to be the highest tolerated dose, but this was not fully explored as the study was terminated early due to excess toxicity. Conclusion PF-06664178 showed toxicity at high dose levels with modest antitumor activity. Neutropenia, skin rash and mucosal inflammation were dose limiting toxicities. Findings from this study may potentially aid in future antibody drug conjugate design and trials.

Prognostic role and clinical significance of trophoblast cell surface antigen 2 in various carcinomas

Introduction

Trophoblast cell surface antigen 2 (TROP2) has been linked to disease prognosis in various human cancers and plays a critical role in tumor development, progression, and metastasis. A number of relevant studies have been published on this topic. A meta-analysis of the latest literature to evaluate the value of TROP2 as a predictive prognosticator of cancer was performed.

Methods

Several online databases were searched, and relevant articles were retrieved. Overall and subcategory meta-analyses were performed, and results were collated.

Results

Twenty-seven articles, including 29 studies, were included, involving 4,852 cancer patients, and results showed that the above-baseline expression of TROP2 was significantly associated with poorer overall survival (OS) (pooled hazard ratio [HR]: 1.84, 95% confidence interval [CI]: 1.45–2.35), disease-free survival (DFS) (pooled HR: 2.77, 95% CI: 1.73–4.42), and progression-free survival (PFS) (pooled HR: 1.71, 95% CI: 1.25–2.35). The following clinical characteristics were also significantly linked with TROP2 overexpression: moderate/poor differentiation (pooled HR: 3.03, 95% CI: 1.99–4.63), distant metastasis (pooled HR: 2.46, 95% CI: 1.05–5.75), lymph node metastasis (pooled HR: 2.47, 95%: CI 1.72–3.56), and advanced TNM stage (pooled HR: 2.02, 95% CI: 1.38–2.95).

Conclusion

TROP2 overexpression was predictive of poor prognosis in human cancers and may be an independent prognostic predictive biomarker. Further studies should be performed to confirm the significance of TROP2 in clinical practice.

The Significance of TROP2 Expression in Predicting BRAF Mutations in Papillary Thyroid Carcinoma

BACKGROUND

Trophoblast antigen 2 (TROP2) is a human trophoblast cell-surface glycoprotein that is overexpressed in several types of epithelial cancers, and is suggested to be associated with an unfavorable prognosis. BRAF mutations are the most common genetic alteration in papillary thyroid carcinoma (PTC). We evaluated the correlation between TROP2 expression and BRAF mutation in PTC.

METHODS

First, we carried out pyrosequencing for BRAF mutations and immunohistochemistry for TROP2 expression with a tissue microarray consisting of 52 PTC cases. Membranous staining in at least 5% of tumor cells was designated as positive staining and we analyzed the relationship between TROP2 expression and diverse clinicopathological factors, including BRAF mutation. Second, we tested TROP2 mRNA expression in three thyroid cancer cell lines with BRAF mutations (BCPAP, SNU790, and 8505C) and a normal thyroid cell line. Additionally, we checked TROP2 protein levels in a normal thyroid cell line after introduction of the BRAF V600E mutation.

RESULTS

In this study, 21 of 26 cases with BRAF mutation showed TROP2 immunoreactivity, whereas all 26 cases without BRAF mutation showed no immunoreactivity for TROP2 with a statistically significant difference (p<.001). Upregulation of TROP2 mRNA was observed in all three thyroid cancer cell lines, but not in the normal thyroid cell line. Interestingly, however, the TROP2 expression was increased in the normal thyroid cell line after introduction of the BRAF V600E mutation.

CONCLUSIONS

Based on these results, we concluded that TROP2 expression is significantly associated with BRAF mutation and that TROP2 immunohistochemistry could be used for predicting BRAF mutations or diagnosing papillary thyroid carcinoma.

Overexpression of TROP2 promotes proliferation and invasion of ovarian cancer cells

Human trophoblastic cell-surface marker, tumor-associated calcium signal transducer 2 (TROP2), is a newly identified marker that has a vital role in the proliferation and invasion of various tumors. However, its specific function in ovarian cancer has not been researched. The purpose of the present study was to investigate the role of TROP2 in the formation of ovarian cancer and its possible mechanism. TROP2 was knocked down by small interfering (si)RNA in ovarian cancer cell line, A2780. The expression of TROP2 protein following transfection was detected by western blot analysis. Cell viability was determined using a Cell Counting kit-8. Cancer cell migration and invasion were examined by wound healing and cell invasion assays, respectively. Apoptosis-related proteins, such as B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax), were measured by western blotting. Results demonstrated that the expression levels of TROP2 were markedly downregulated by siRNA in A2780 cells compared with the control groups, which led to strong inhibition of proliferation and invasion. Furthermore, TROP2 downregulation also reduced cell migratory ability. Additionally, in the TROP2-knockout group, Bcl-2 was downregulated and Bax was upregulated compared with the control. The present study suggested that the expression of TROP2 was related to cellular proliferation, migration and invasion. TROP2 may disrupt the balance in the Bax family to participate in apoptosis regulation in A2780 cells. Therefore, the overexpression of TROP2 may have a crucial role in tumorigenesis and tumor progression by disturbing the Bax/Bcl-2 balance in ovarian cancer.

Trop2 promotes proliferation, invasion and EMT of nasopharyngeal carcinoma cells through the NF-κB pathway

Human trophoblast cell surface antigen 2 (Trop2), a cell surface transmembrane glycoprotein receptor, has been demonstrated to be closely associated with increasing tumor aggressiveness, metastasis and unfavorable prognosis.

Impact of TROP2 expression on prognosis in solid tumors: A Systematic Review and Meta-analysis

Over-expression of TROP2 (the trophoblast cell surface antigen 2) was reported to predict poor prognosis in various solid tumors in number of studies. However, the results remained not comprehensive. Therefore, we here carried out this meta-analysis of relevant studies published on this topic to quantitatively evaluate the clinicopathological significance of TROP2 in solid tumors. Relevant articles were identified through searching the PubMed, Web of Science and Embase database. The primary outcomes were overall survival (OS) and disease-free survival (DFS). In this meta-analysis, 16 studies involving 2,569 participants were included, and we drew the conclusion that TROP2 overexpression was significantly associated with poor OS (pooled HR = 1.896, 95% CI = 1.599–2.247, P < 0.001) and short DFS (pooled HR = 2.336, 95% CI = 1.596–3.419, P < 0.001). Furthermore, the subgroup analysis revealed that the associations between TROP2 overexpression and the outcome endpoints (OS or DFS) were significant in in patients with female genital system neoplasms, as well in gastrointestine neoplasms. In addition, subgroup analysis found no difference HR across populations of different descent.Taken together, TROP2 overexpression was associated with poor survival in human solid tumors. TROP2 may be a valuable prognosis predictive biomarker and a potential therapeutic target in human solid tumors.

RN927C, a Site-Specific Trop-2 Antibody-Drug Conjugate (ADC) with Enhanced Stability, Is Highly Efficacious in Preclinical Solid Tumor Models

Trop-2, also known as TACSTD2, EGP-1, GA733-1, and M1S1, is frequently expressed on a variety of human carcinomas, and its expression is often associated with poor prognosis of the diseases. However, it is also present on the epithelium of several normal tissues. A comprehensively designed Trop-2-targeting antibody-drug conjugate (ADC), balancing both efficacy and toxicity, is therefore necessary to achieve clinical utility. To this end, we developed a cleavable Trop-2 ADC (RN927C) using a site-specific transglutaminase-mediated conjugation method and a proprietary microtubule inhibitor (MTI) linker-payload, PF-06380101. Robust in vitro cytotoxicity of RN927C was observed on a panel of Trop-2-expressing tumor cell lines, with IC₅₀ generally in the subnanomolar range. As expected for an MTI-containing ADC, RN927C readily induced mitotic arrest of treated cells in vitro and in vivo, followed by subsequent cell death. The in vivo efficacy of RN927C was tested in multiple cell line and patient-derived xenograft tumor models, including pancreatic, lung, ovarian, and triple-negative breast tumor types. Single-dose administration of RN927C at 0.75 to 3 mg/kg was generally sufficient to induce sustained regression of Trop-2-expressing tumors and showed superior efficacy over standard treatment with paclitaxel or gemcitabine. Administration of RN927C in nonhuman primate toxicity studies resulted in target-mediated effects in skin and oral mucosa, consistent with Trop-2 expression in these epithelial tissues with minimal, non-dose limiting off-target toxicities. On the basis of the combined efficacy and safety results, RN927C is postulated to have a favorable therapeutic index for treatment of solid tumors. Mol Cancer Ther; 15(11); 2698-708. ©2016 AACR.

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

Trop2 is a transmembrane glycoprotein encoded by the Tacstd2 gene. It is an intracellular calcium signal transducer that is differentially expressed in many cancers. It signals cells for self-renewal, proliferation, invasion, and survival. It has stem cell-like qualities. Trop2 is expressed in many normal tissues, though in contrast, it is overexpressed in many cancers and the overexpression of Trop2 is of prognostic significance. Several ligands have been proposed that interact with Trop2. Trop2 signals the cells via different pathways and it is transcriptionally regulated by a complex network of several transcription factors. Trop2 expression in cancer cells has been correlated with drug resistance. Several strategies target Trop2 on cancer cells that include antibodies, antibody fusion proteins, chemical inhibitors, nanoparticles, etc. The in vitro studies and pre-clinical studies, using these various therapeutic treatments, have resulted in significant inhibition of tumor cell growth both in vitro and in vivo in mice. A clinical study is underway using IMMU-132 (hrS7 linked to SN38) in patients with epithelial cancers. This review describes briefly the various characteristics of cancer cells overexpressing Trop2 and the potential application of Trop2 as both a prognostic biomarker and as a therapeutic target to reverse resistance.

Overexpression of TROP2 predicts poor prognosis of patients with cervical cancer and promotes the proliferation and invasion of cervical cancer cells by regulating ERK signaling pathway

Overwhelming evidence has demonstrated that the aberrant expression of the human trophoblast cell-surface antigen (TROP2) was associated with tumor aggressiveness and poor prognosis in a variety of human cancers, however the roles of TROP2 in cervical cancer have not been investigated. The purpose of our study was to elucidate the prognostic significance of TROP2 expression in patients with cervical cancer and determine its effect on tumor progression. Immunohistochemistry assay showed that 88.7% (94/106 cases) of cervical cancer specimens were positively stained with TROP2, and the overexpression of TROP2 was closely related with FIGO stage, histological grades, lymphatic metastasis, invasive interstitial depth and high expression of Ki-67. Patients with TROP2-positive staining exhibited a significantly decreased overall survival and progression free survival; it was also an independent predictor for prognosis according to multivariate analysis. Moreover, down-regulation of TROP2 mediated by siRNA in Siha and CaSki cells resulted in a strong inhibition of proliferation and invasion, TROP2 abrogation also elevated the apoptotic ratio and caused G1 arrest. Conversely, enforced expression of TROP2 in HeLa and C33A cells remarkably promoted cell growth, migration and invasion. In addition, the tumorigenic function of TROP2 was associated with the increased expressions of cyclin D1, cyclin E, CDK2 and CDK4 but reduced expression of p27 and E-cadherin via the activation of Erk1/2 signaling pathway. Furthermore, the inhibition of TROP2 expression in cervical cancer cell lines enhances sensitivity to cisplatin. The present study suggest that overexpression of TROP2 may play crucial roles in the development and pathogenesis of human cervical cancer, therefore, TROP2 may represent a prospective prognostic indicator and a potential therapeutic target of cervical cancer.

A novel human Fab antibody for Trop2 inhibits breast cancer growth in vitro and in vivo

Human trophoblastic cell surface antigen 2 (Trop2) has been suggested as an oncogene, which is associated with the different types of tumors. In this study, a human Fab antibody against Trop2 extracellular domain was isolated from phage library by phage display technology, and characterized by ELISA, FACS, fluorescence staining and Western blotting analysis. MTT, apoptosis assay and wound healing assay were employed to evaluate the inhibitory effects of Trop2 Fab on breast cancer cell growth in vitro, while tumor-xenograft model was employed to evaluate the inhibitory effects on breast cancer growth in vivo. The results showed that Trop2 Fab inhibited the proliferation, induced the apoptosis and suspended the migration of MDA-MB-231 cells in a dose dependent manner. The expression caspase-3 was activated, and the expression of Bcl-2 was reduced while that of Bax was elevated in MDA-MB-231 cells by treating with Trop2 Fab. In addition, Trop2 Fab inhibited the growth of breast cancer xenografts and the expression of Bcl-2 was reduced while that of Bax was elevated in xenografts. Trop2 Fab, which was isolated successfully in this research, is a promising therapeutic agent for the treatment of Trop2 expressing breast cancer.

Emerging therapeutic biomarkers in endometrial cancer

Although clinical trials of molecular therapies targeting critical biomarkers (mTOR, epidermal growth factor receptor/epidermal growth factor receptor 2, and vascular endothelial growth factor) in endometrial cancer show modest effects, there are still challenges that might remain regarding primary/acquired drug resistance and unexpected side effects on normal tissues. New studies that aim to target both genetic and epigenetic alterations (noncoding microRNA) underlying malignant properties of tumor cells and to specifically attack tumor cells using cell surface markers overexpressed in tumor tissue are emerging. More importantly, strategies that disrupt the cancer stem cell/epithelial-mesenchymal transition-dependent signals and reactivate antitumor immune responses would bring new hope for complete elimination of all cell compartments in endometrial cancer. We briefly review the current status of molecular therapies tested in clinical trials and mainly discuss the potential therapeutic candidates that are possibly used to develop more effective and specific therapies against endometrial cancer progression and metastasis.