Trophoblast Antigens Research Articles

Sacituzumab-govitecan-induced severe acute tubulointerstitial nephritis requiring hemodialysis

BackgroundSacituzumab govitecan is an antibody-drug conjugate that is FDA approved for refractory metastatic triple-negative breast cancer. It targets the human trophoblastic cell-surface antigen 2 (Trop-2) with SN-38, a topoisomerase I inhibitor, attached to the antibody [1]. SN-38 breaks DNA strands and induces tumor apoptosis [2]. Acute kidney injury (AKI) is one of its adverse effects mainly prerenal due to gastrointestinal toxicity, but it has not been reported to cause acute tubulointerstitial nephritis (ATIN).Case PresentationThis report describes a rare adverse effect of sacituzumab govitecan, the approach to diagnosing the etiology of the patient’s AKI, and the mechanism by which sacituzumab govitecan causes ATIN. A woman with metastatic ER positive, PR positive, HER2 negative breast cancer who was initiated on sacituzumab govitecan presents with vomiting and diarrhea, and findings of nephrotic-range proteinuria, negative anti-PLA2R antibody, and severe AKI requiring hemodialysis. She underwent kidney biopsy and pathology showed ATIN characterized by patchy interstitial inflammation alongside tubular injury without glomerular and vascular involvement. With intermittent renal replacement therapy, furosemide challenge, and a course of prednisone, the patient’s kidney function recovered.ConclusionsSacituzumab has a high affinity for Trop-2 protein which is also expressed within the collecting ducts, and to a lesser extent, the proximal tubule. Individuals, such as this patient, who express a homozygous genotype for UGT1A1*28 allele are at increased risk for AKI from sacituzumab govitecan due to decreased glucuronidation of SN-38.

Potential mechanisms of interstitial lung disease induced by antibody-drug conjugates based on quantitative analysis of drug distribution.

Antibody-drug conjugates (ADCs) are a rapidly advancing category of therapeutic agents with notable anti-cancer efficacy. However, the emergence of interstitial lung disease (ILD) as a severe ADC-associated adverse event highlights the need to better understand the underlying mechanisms. In this study, xenograft model mice with tumors expressing different levels of the trophoblast antigen 2 (TROP2) were generated by subcutaneously transplanting the various TROP2-expression cancer lines. The mice received different doses of TROP2-eribulin, a novel TROP2-targeting ADC, composed of an anti-TROP2 antibody and the eribulin payload, joined by a cleavable linker. The concentration and distribution of TROP2-eribulin, as well as the pharmacokinetics of eribulin release, were assessed in tumor and lung tissues. Analysis of tumor tissue showed that the concentration of released eribulin was approximately 10-fold higher in NCI-H2110 (high TROP2 expression) than in A549 (low TROP2 expression), while analysis of lung tissue showed that TROP2-eribulin was distributed in lung tissue in a dose-dependent manner of TROP2-eribulin regardless of TROP2 expression, with significantly more eribulin released in the high-dose group than in the other dose groups (P < 0.05). Immunofluorescence assay analysis showed that TROP2-eribuilin localized to alveolar macrophages. In the analysis using human- leukemia monocytic cell, the concentration of eribulin released from TROP2-eribuilin was significantly reduced by the use of an Fc receptor inhibitor (P < 0.05). These results revealed that Fcγ-receptor-mediated uptake by alveolar macrophages releases cytotoxic payload into lung tissue, helping to clarify the pathogenesis of ADC-induced ILD.

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.

1471TiP MK-2870-015: A phase III study of trophoblast antigen 2 (TROP2)-directed antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT) vs treatment of physician’s choice (TPC) for previously treated metastatic gastroesophageal adenocarcinoma (GEA)

1471TiP MK-2870-015: A phase III study of trophoblast antigen 2 (TROP2)-directed antibody-drug conjugate (ADC) sacituzumab tirumotecan (sac-TMT) vs treatment of physician’s choice (TPC) for previously treated metastatic gastroesophageal adenocarcinoma (GEA)

Preliminary exploration of Trop2 ADC in combination with immune checkpoint inhibitors in the different molecular subtypes of invasive breast carcinoma.

e12558 Background: Human trophoblastic cell surface antigen 2 (Trop2) is a transmembrane protein overexpressed in breast cancer tissues. However, it is present at minimal levels in adult somatic tissues, making it an ideal target for treatment with antibody-drug conjugates (ADCs). Sacituzumab govitecan, an anti-Trop2 ADC, has been approved for the treatment of triple-negative breast cancer and urothelial cancer. Recent studies have demonstrated that human cytotoxic T lymphocytes can recognize Trop2. Accordingly, we aimed to assess the role of Trop2 in the tumor immune activity of different subtypes of breast cancer, and laying the foundation for further studies on the efficacy of the combination of Trop2 ADC and immune checkpoint inhibitors in breast cancer. Methods: We retrospectively retrieved tissues from 152 invasive breast carcinoma of no special type and 111 benign breast tumor tissues and undergoing surgical resection at our institution from 2018 to 2023. Immunohistochemistry was used to detect Trop2 and PD-L1 expression and lymphatic invasion in patients, and their correlations with clinicopathological factors were analyzed. Trop2 expression was evaluated using the H-score. The median as the cut-off value, a score of 0–240 indicated low expression, and 240–300 indicated high expression. Cases with CPS ≥ 1% were considered positive for PD-L1. Results: The expression was Trop2 in breast cancer tissues than in benign tumor tissues (P&lt;0.0001). Immune infiltration analysis suggested that Trop2 expression was correlated with immune cell infiltration and the abundance (P&lt;0.001). Kaplan–Meier plotter analysis demonstrated that high Trop2 expression was related to poor prognosis in patients with triple-negative breast cancer (overall survival: HR=1.53, P=0.029; relapse-free survival: HR=1.26, P=0.045). In contrast, Trop2 expression was not significantly associated with prognosis in other breast cancer subtypes. However, there was no statistically significant correlation found between PD-L1 expression and Trop-2 expression in breast cancer. Conclusions: The findings suggest that Trop2 correlates with poor prognosis and immune cell infiltration in breast cancer. This indicates the role of Trop2 as a potential prognostic biomarker, laying the foundation for further research focusing on the immune regulatory role of Trop2. [Table: see text]

SMART: A phase II study of sacituzumab govitecan (SG) with or without atezolizumab immunotherapy in rare genitourinary (GU) tumors such as small cell, adenocarcinoma, and squamous cell bladder/urinary tract cancer, renal medullary carcinoma (RMC) and penile cancer.

TPS4627 Background: Rare tumors of the GU tract often exhibit aggressive clinical behavior, yet lack effective standard of care treatment options. SG is an antibody-drug conjugate (ADC) targeting trophoblastic cell surface antigen 2 (Trop2) with a payload of SN-38, a topoisomerase inhibitor. SG monotherapy gained accelerated approval in pts with metastatic urothelial carcinoma (mUC) post platinum and immune-checkpoint inhibitor (ICI) therapy based on the TROPHY-U-01 trial (Tagawa S et al., JCO 2021). Atezolizumab is an anti-PD-L1 ICI approved for use in multiple solid tumors. SMART will evaluate the efficacy and safety of SG monotherapy or SG plus atezolizumab in select rare GU tumors. Methods: SMART is an open-label, non-randomized, Phase 2 trial. Pts must have locally advanced (unresectable) or metastatic GU tumors of the following histologies: small cell carcinoma, squamous cell carcinoma, or primary adenocarcinoma of the bladder or urinary tract, RMC, or squamous cell carcinoma of the penis. Pts may be treatment-naïve or have received any number of prior therapies; pts with small cell carcinoma must have received a platinum-based regimen. Pts treated with a PD-1/PD-L1 ICI will be assigned to Cohort A/Treatment Arm 1 and will receive SG monotherapy (10mg/kg IV, D1 and D8 of 21 day cycles). Pts without prior ICI treatment will be assigned to Cohort B/Treatment Arm 2 and will receive SG (10mg/kg IV, D1 and D8 of 21 day cycles) with concomitant atezolizumab (1200mg IV, D1 of 21 day cycles). Treatment will continue until disease progression (max duration of treatment 5 years) or intolerable side effects. The primary endpoint is objective response rate (ORR) (RECIST v1.1) for each Cohort, with restaging every 3 cycles. Secondary endpoints include safety, clinical benefit rate (CR+PR+SD), median PFS/OS for each Cohort, and ORR for each histology. Exploratory analyses include determination of baseline tumor mutation and transcriptional profile, Trop2 expression, ctDNA/CTCs, peripheral blood immune subsets and cytokine profile correlation with response, and correlation of UGT1A1 allele genotype with response and safety. This study utilizes a Simon minimax two-stage design, with enrollment of up to 43 evaluable pts (accrual ceiling of 60 pts). Cohort A will enroll 11 pts in Stage 1; if 1 or more of the first 11 pts has a response (unacceptably low rate of 5%, p0=0.05; alpha 0.10, beta=0.20), accrual will continue into Stage 2 up to 18 evaluable pts. Cohort B will enroll 16 evaluable pts in Stage 1; if 2 or more pts have a response (unacceptably low rate of 10%, p0=0.10; alpha 0.10, beta=0.10), accrual will continue in Stage 2 up to a total of 25 evaluable pts. This study is open at the NIH Clinical Center (CC); enrollment may open at 1-2 additional centers. Clinical trial information: NCT06161532 .

TROP2 promotes PINK1-mediated mitophagy and apoptosis to accelerate the progression of senile chronic obstructive pulmonary disease by up-regulating DRP1 expression

Chronic obstructive pulmonary disease (COPD) is a chronic airway inflammatory disease characterised by irreversible airflow limitation. The elderly are a vulnerable population for developing COPD. With the growth of age, physiological degenerative changes occur in the thorax, bronchus, lung and vascular wall, which can lead to age-related physiological attenuation of lung function in the elderly, so the prevalence of COPD increases with age. Its pathogenesis has not yet been truly clarified. Mitophagy plays an important role in maintaining the stability of mitochondrial function and intracellular environment by scavenging damaged mitochondria. Currently, studies have shown that trophoblast antigen 2 (TROP2) expression is up-regulated in airway basal cells of patients with COPD, suggesting that TROP2 is involved in the progression of COPD. However, whether it is involved in disease progression by regulating mitochondrial function remains unclear. In this study, compared with non-smoking non-COPD patients, the expression of TROP2 in lung tissues of smoking non-COPD patients and patients with COPD increased, and TROP2 expression in patients with COPD was higher than that in smoking non-COPD patients. To further explore the role of TROP2, we stimulated BEAS-2B with cigarette smoke to construct an in vitro model. We found that TROP2 expression increased, whereas TROP2 silencing reversed the cigarette smoke extract-induced decrease in mitochondrial membrane potential, increased reactive oxygen species content, decreased adenosine triphosphate (ATP) production, increased inflammatory factor secretion and increased apoptosis. In addition, we searched online bioinformatics and screened the gene dynamin-related protein 1 (DRP1) related to mitophagy as the research object. Co-IP assay verified the binding relationship between DRP1 and TROP2. Further study found that TROP2 promoted mitophagy and apoptosis of BEAS-2B cells by up-regulating the expression of DRP1. In addition, PTEN-induced putative kinase 1 (PINK1) is a potential binding protein of DRP1, and DRP1 accelerated mitophagy and apoptosis of BEAS-2B cells by promoting the expression of PINK1. We established a COPD SD rat model by cigarette smoke exposure and LPS instillation and treated it by intraperitoneal injection of si-TROP2. The results showed that TROP2 silencing restored lung function and reduced the secretion of inflammatory factors in bronchoalveolar lavage fluid. In conclusion, TROP2 can be used as a new reference for COPD treatment.

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.

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 upregulated 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 Chi-squared analyses or Fischer' exact tests. The associations of TROP2 expression and pathologic parameters with survival were evaluated by Kaplan-Meier method, 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=0.04) and higher number (P=0.03) of lymph node metastasis, higher pN stage (P=0.03), less frequent adenoma (P=0.04), and higher frequency of recurrence/metastasis (P=0.004). TROP2 expression was associated with shorter disease-free survival (P=0.02) and overall survival (P=0.03). TROP2 expression was an independent prognostic factor for disease-free survival (P=0.04). We demonstrated 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 therapeutic target for patients with AAs.

Abstract 6297: Rationale for the development of a differentiated Trop2 ADC

Abstract Background: Trophoblast antigen 2 (Trop2) or Tumor-Associated Calcium Signal Transducer 2 (TACSTD2) is a transmembrane glycoprotein that is overexpressed in several solid tumor cancers. Antibody drug conjugate (ADC) targeting of Trop2 has been clinically validated. The Trop2 ADC Trodelvy® (also known as Sacituzumab govitecan/IMMU-132) is approved for therapy of TNBC and urothelial cancer, and Datopotamab DXd (DS-1062) is currently being tested in NSCLC. Peak Bio’s Thailanstatin suite of immunomodulatory linker-toxins (L-Ts) is a set of 7 related molecules with distinct ADC features that have been extensively characterized in vitro and in vivo as Her2 ADCs and is being used as a platform to generate a pipeline of potentially differentiated ADCs (AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1832). Results: M2.8 is a fully humanized Peak Bio antibody (Ab) that targets human Trop2 (hTrop2) with high binding affinity [Kd (M)= 8.97-09]. M2.8 was optimized for binding affinity and humanization relative to its parent M2.1 [Kd (M)= 1.78-08], and, both M2.1 and M2.8, display species-specificity for the human and cynomolgus monkey Trop2 proteins. When bound to hTrop2-positive cell lines, M2.1 and M2.8 can rapidly internalize and deliver an ADC payload. To identify the optimal release for therapeutic efficacy, we conjugated our family of L-Ts with hRS7 at a comparable drug-to-antibody ratio (DAR) of 4. Maximal tumor growth inhibition (TGI) was associated with the Trop2 ADCs that were conjugated via amine coupling to lysine residues using non-cleavable L-T L22, later renamed PH1. To determine the effect of antibody on TGI efficacy, different doses, and DARs of M2.1 PH1 ADC were compared to PH1 ADCs made from other Trop2 Abs. At low dose levels, M2.1 PH1 ADCs exhibited comparable TGI with hRS7 PH1, TINA PH1, and T6-16 PH1 ADCs, but exhibited significantly greater TGI than hRS7 SN38 (IMMU-132), suggesting that payload potency, rather than epitope, was important in targeting Trop2. The results also suggested that a PH1 DAR of 4 was sufficient to obtain 90% TGI with multiple anti-Trop2 Abs. M2.1 PH1 ADC was safely tolerated by cynomolgus monkeys at 3 and 6 mg/kg Q3W x 3 doses with mild-to-moderate changes in liver enzymes and platelets that reversed to baseline within 7-10 days of administration of each dose. The optimized M2.8 PH1 DAR4 ADCs killed Trop2-positive cell lines with single-digit nanomolar potency, while exhibiting low off-target cytotoxicity vs normal human skin fibroblasts and Trop2-negative cell lines in vitro. M2.8 PH1 ADC regressed all 200mm3 sized NCI-N87 tumors and 50% of these tumors exhibited long-term regression for 5 months. Conclusion: The target validation studies suggest that Trop2 PH1 ADCs were sufficiently differentiated in areas of preclinical efficacy and well tolerated in a toxicologically relevant host. Citation Format: Satyajit K. Mitra, William Monteith, Mary Do, Greg Tuffy, Scott Savage, Jeffrey Kang, Mastewal Abuhay, Teodora Losic, Sanjeevani Ghone, William E. Haskins, Vasu Jammalamadaka, Sanjeev Satyal. Rationale for the development of a differentiated Trop2 ADC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6297.

Expression and Therapeutic Targeting of TROP-2 in Treatment-Resistant Prostate Cancer.

Men with metastatic castration-resistant prostate cancer (mCRPC) frequently develop resistance to androgen receptor signaling inhibitor (ARSI) treatment; therefore, new therapies are needed. Trophoblastic cell-surface antigen (TROP-2) is a transmembrane protein identified in prostate cancer and overexpressed in multiple malignancies. TROP-2 is a therapeutic target for antibody-drug conjugates (ADC). TROP-2 gene (TACSTD2) expression and markers of treatment resistance from prostate biopsies were analyzed using data from four previously curated cohorts of mCRPC (n = 634) and the PROMOTE study (dbGaP accession phs001141.v1.p1, n = 88). EPCAM or TROP-2-positive circulating tumor cells (CTC) were captured from peripheral blood for comparison of protein (n = 15) and gene expression signatures of treatment resistance (n = 40). We assessed the efficacy of TROP-2-targeting agents in a mouse xenograft model generated from prostate cancer cell lines. We demonstrated that TACSTD2 is expressed in mCRPC from luminal and basal tumors but at lower levels in patients with neuroendocrine prostate cancer. Patients previously treated with ARSI showed no significant difference in TACSTD2 expression, whereas patients with detectable AR-V7 expression showed increased expression. We observed that TROP-2 can serve as a cell surface target for isolating CTCs, which may serve as a predictive biomarker for ADCs. We also demonstrated that prostate cancer cell line xenografts can be targeted specifically by labeled anti-TROP-2 agents in vivo. These results support further studies on TROP-2 as a therapeutic and diagnostic target for mCRPC.

Akkermansia muciniphila Ameliorates Lung Injury in Smoke-Induced COPD Mice by IL-17 and Autophagy

Objective. Smoking is a primary hazard factor for chronic obstructive pulmonary disease (COPD), which induced a decrease in intestinal Akkermansia muciniphila abundance and Th17 imbalance in COPD. This study analyzed the changes of gut microbiota metabolism and Akkermansia abundance in patients with smoking-related COPD and explored the potential function of Akkermansia muciniphila in smoke-induced COPD mice. Methods. Gut microbiota diversity and metabolic profile were analyzed by 16S rRNA sequence and metabolomics in COPD patients. The IL-1β, IL-17, TNF-α, and IL-6 levels were tested by ELISA. Lung tissue damage was observed by HE staining. The expression of cleave-caspase 3, trophoblast antigen 2 (TROP2), and LC3 in lung tissues were analyzed by IHC or IF. The p-mTOR, mTOR, p62, and LC3 expression in lung tissues were tested by western blot. Results. The levels of IL-17, IL-1β, TNF-α, and IL-6 in the peripheral blood of COPD patients increased significantly. The number and alpha diversity of gut microbiota were decreased in COPD patients. The abundance of Akkermansia muciniphila in gut of COPD patients was decreased, and the metabolic phenotype and retinol metabolism were changed. In the retinol metabolism, the retinol and retinal were significantly changed. Akkermansia muciniphila could improve the alveolar structure and inflammatory cell infiltration in lung tissue, reduce the IL-17, TNF-α, and IL-6 levels in peripheral blood, promote the p-mTOR expression, and inhibit the expression of autophagy-related proteins in smoke-induced COPD mice. Conclusion. The number and alpha diversity of gut microbiota were decreased in patients with smoking-related COPD, accompanied by decreased abundance of Akkermansia muciniphila, and altered retinol metabolism function. Gut Akkermansia muciniphila ameliorated lung injury in smoke-induced COPD mice by inflammation and autophagy.

AB007. Expression of trophoblastic antigen 2 (Trop2) in thymic epithelial tumors

AB007. Expression of trophoblastic antigen 2 (Trop2) in thymic epithelial tumors

Влияние векторной вакцины от COVID-19 на профиль аутоантител у женщин репродуктивного возраста

Autoimmune mechanisms have been implicated in the negative effects of vaccines on female reproductive health. This study evaluates the endogenous levels of self-reactive antibodies and ovarian reserve-associated hormones before and after immunization with the domestically developed Gam-COVID-Vac combined vector vaccine to check for possible reproductive sequelae. The prospective study enrolled 120 women aged 18–49, subject to vaccination with Gam-COVID-Vac. Ovarian reserve was assessed prior to vaccination and 90 days after the first component injection. Profiles of specific antibodies to self-antigens, including phospholipids, nuclear antigens, FSH, progesterone, and also thyroid, ovarian, trophoblast, and zona pellucida antigens, were assessed at the same time points by enzyme immunoassay. Overall, the vaccination had no effect on the levels of ovarian reserve-associated hormones and autoantibodies, apart from a transient increase in positivity for antiphosphatidylethanolamine IgM and anti-dsDNA IgG. Seroprevalence of elevated serum autoantibodies constituted 70.8% before and 75% after vaccination. According to the results, immunization with Gam-COVID-Vac does not affect ovarian reserve or autoimmune status, thus being safe for the female reproductive potential.

Establishment of fetomaternal tolerance through glycan-mediated Bcell suppression.

Discrimination of self from non-self is fundamental to a wide range of immunological processes1. During pregnancy, the mother does not recognize the placenta as immunologically foreign because antigens expressed by trophoblasts, the placental cells that interface with the maternal immune system, do not activate maternal T cells2. Currently, these activation defects are thought to reflect suppression by regulatory T cells3. By contrast, mechanisms of Bcell tolerance to trophoblast antigens have not been identified. Here we provide evidence that glycan-mediated Bcell suppression has a key role in establishing fetomaternal tolerance in mice. B cells specific for a model trophoblast antigen are strongly suppressed through CD22-LYN inhibitory signalling, which in turn implicates the sialylated glycans of the antigen as key suppressive determinants. Moreover, B cells mediate the MHC-class-II-restricted presentation of antigens to CD4+ T cells, which leads to T cell suppression, and trophoblast-derived sialoglycoproteins are released into the maternal circulation during pregnancy in mice and humans. How protein glycosylation promotes non-immunogenic placental self-recognition may have relevance to immune-mediated pregnancy complicationsand to tumour immune evasion. We also anticipate that our findings will bolster efforts to harness glycan biology to control antigen-specific immune responses in autoimmune disease.

N-glycosylation status of Trop2 impacts its surface density, interaction with claudin-7 and exosomal release

Trophoblast antigen 2 (Trop2) is a type I transmembrane protein post-translationally modified by N-linked glycosylation. It was originally detected in trophoblasts but was later shown to be frequently overexpressed in many epithelial cancers. Recently, anti-Trop2 antibody-drug conjugate has been FDA approved for the treatment of metastatic triple-negative breast and urothelial carcinomas, making it an important tumor antigen. The current study explored the significance of N-glycosylation of Trop2 by substituting specific N-glycan addition sites by site-directed mutagenesis. The mutant proteins were characterized in transiently transfected HEK293 cells. The N-glycosylation mutants did not affect protein expression, stability, dimerization ability and matriptase mediated cleavage. However, N120A and N208A mutants showed decreased interaction with its binding partner claudin-7. Our earlier reported Trop2 mutant V194A, which shows aberrant glycosylation, also displayed hampered interaction with claudin-7. To further characterize the mutants, stable clones expressing wild type and mutant Trop2 were generated in OVCAR3 cell line. Interestingly, surface biotinylation assay showed significantly higher surface expression of N120A and N208A mutants whereas surface localization was drastically reduced for V194A Trop2 mutant. Though overexpression of wild type Trop2 did not cause any change in fibronectin-mediated FAK (Focal adhesion kinase) signaling; expression of N120A mutant, surprisingly downregulated FAK signaling. Furthermore, exosomal release of Trop2 was also decreased in N120A and N208A mutants. This data suggests that site-specific N-glycan addition determines Trop2 surface density, claudin-7 interaction and exosomal release.

Tackling metastatic triple-negative breast cancer with sacituzumab govitecan

ABSTRACT Introduction Metastatic triple-negative breast cancer (TNBC) is an aggressive cancer with poor survival that is difficult to treat due to a lack of targeted options. Conventional therapies targeting hormone receptors (HR) and human epidermal growth factor 2 (HER2) are ineffective and often chemotherapy is standard-of-care. Sacituzumab govitecan is an antibody drug conjugate (ADC) comprised of an active metabolite of irinotecan, SN-38, bound to a humanized monoclonal antibody targeting trophoblastic cell-surface antigen 2 (Trop-2). Trop-2 is highly expressed on the surface of TNBC cells, making it an attractive target. Areas covered We explore the mechanism, pharmacology, efficacy, safety, and tolerability of sacituzumab govitecan. A literature search was conducted via PubMed using keywords such as ‘sacituzumab govitecan,’ and ‘metastatic TNBC.’ Expert opinion Sacituzumab govitecan has promising survival benefits in patients with previously treated mTNBC based on data from the ASCENT trial. Common adverse effects were neutropenia, diarrhea, and nausea, however these effects were manageable with supportive care. Sacituzumab govitecan has shown promise in cancers outside of TNBC, such as urothelial and lung and is being evaluated in HR-positive breast cancers. It is likely we will see this therapy used in combination with other novel targeted agents as current clinical trials mature.

CD22/Lyn-mediated suppression of trophoblast antigen-specific B cells underlies fetomaternal tolerance

Abstract The placenta releases allogeneic trophoblast antigens into maternal circulation during pregnancy. Maternal antigen presenting cells present these antigens to T cells but fail to induce strong immunogenic responses, even in the presence of danger signals. While this observation illustrates the phenomenon of fetomaternal tolerance, its cellular and molecular basis remains largely unknown. By studying the pathways mediating adaptive immune responses to a surrogate trophoblast antigen in mice, we found that maternal B cells, and not regulatory T cells, directly underlie the impairments in CD4 T cell activation. Trophoblast-antigen specific B cells, rather than dendritic cells, are the main presenters of trophoblast antigen to CD4 T cells. The B cells are themselves profoundly suppressed, thus limiting their ability to activate cognate CD4 T cells. Mechanistically, B cell suppression occurs as the result of CD22/Lyn inhibitory signaling, likely induced by sialic acid residues that coat the trophoblast-derived antigen. These results not only identify maternal B cells as key players in fetomaternal tolerance but also provide a basis for further work on B cell responses during healthy and pathologic pregnancies. More broadly, these results suggest that exploiting antigen-intrinsic properties such as sialylation may provide new therapeutic ways to ignite or inhibit antigen-specific responses outside the context of pregnancy.

The role and mechanism of human trophoblastic cell surface antigen 2 in the invasion and metastasis of ovarian cancer

Objective: To explore the role and molecular mechanism of trophoblastic cell surface antigen 2 (Trop2) in the invasion and migration of ovarian cancer. Methods: Through the data mining of Cancer Cell Line Encyclopedia and TCGA database, the clinical significance of Trop2 expression was analyzed. Western blot was used to detect Trop2 protein expression in ovarian cancer cell lines including A3O, A1780 and SKOV3. SKOV3 cells were used to construct Trop2-short hairpin RNA (shRNA) cell model. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to detect the SKOV3 mRNA expression in SKOV3-shRNA and SKOV3-NC cells. Cell counting kit-8 (CCK8) was used to detect the proliferation of SKOV3-shRNA cells and SKOV3-NC cells. Flow cytometry was used to detect cell cycle and apoptosis in two groups of cells. Transwell array was used to detecte the invasion and migration of SKOV3-shRNA cells and SKOV3-NC cells. Western blot was used to detect the protein expressions of AKT, p-AKT, β-catenin, caspase3, bcl-2, E-cadherin and vimentin. Results: Trop2 mRNA highly expressed in ovarian cancer, and was related to the tumor stage and patient survival. Compared with A3O cells, Trop2 overexpressed in A1780 and SKOV3 cells (P<0.05). The relative expression levels of Trop2 mRNA in SKOV3-NC group and SKOV3-shRNA group were 1.18±0.24 and 0.42±0.08, with statistically significant difference (P<0.05). The results of CCK-8 array showed that the cell viability of SKOV3-NC group was significantly higher than that of SKOV3-shRNA group (P<0.05). The proportion of G(0)/G(1) cells in SKOV3-NC and SKOV3-shRNA groups were (38.67±4.22)% and (60.24±8.17)%, respectively. G(0)/G(1) arrest was observed in SKOV3-shRNA cells (P<0.05). The apoptosis rate of SKOV3-shRNA group was (26.32±1.81)%, significantly higher than (6.54±1.32)% of SKOV3-NC group (P<0.05). The number of migrating SKOV3 cells in the SKOV3-shRNA and SkOV3-NC groups were 1 255.83±108.44 and 1 679.71±213.92, while the number of invading cells were 242.49±52.09 and 473.54±73.11, respectively. Compared with the SKOV3-NC group, the number of migrating and invading SKOV3-shRNA group was significantly reduced (all P<0.05). The expressions of p-AKT2, Bcl-2, vimentin and β-catenin were down-regulated, and the expressions of caspase 3 and E-cadherin were up-regulated in SKOV3-shRNA cells. There was no significant change in the total protein level of AKT. Conclusions: Trop2 expression is related to ovarian cancer stage and postoperative survival. Trop2 can promote ovarian cancer cell proliferation and metastasis by activating the AKT/β-catenin signaling pathway and knockdown of Trop2 inhibits the progression of ovarian cancer.

Ginsenoside Rb3 Alleviates CSE-induced TROP2 Upregulation through p38 MAPK and NF-κB Pathways in Basal Cells.

Smoking-mediated reprogramming of the phenotype and function of airway basal cells (BCs) disrupts airway homeostasis and is an early event in chronic obstructive pulmonary disease (COPD)-associated airway remodeling. Here, we examined the expression and regulation of the transmembrane glycoprotein TROP2 (trophoblast antigen 2), a putative stem cell marker in airway BCs, in lung tissue samples from healthy smokers and healthy nonsmokers and in models in culture to identify therapeutic targets. TROP2 expression was upregulated in the airway epithelia of smokers and positively correlated with the smoking index. In vitro, cigarette smoke extract (CSE) induced TROP2 expression in airway BCs in a time- and dose-dependent manner. The p38 MAPK and NF-κB pathways were also activated by CSE, and their specific antagonists inhibited CSE-induced TROP2 expression. A therapeutic component derived from traditional Chinese medicine, ginsenoside Rb3, inhibited CSE-induced TROP2 expression as well as activation of the p38 MAPK and NF-κB pathways in BCs in monolayer culture. Furthermore, ginsenoside Rb3 prevented the increase in TROP2 expression and antagonized CSE-induced BC hyperplasia and expression of inflammatory factors and epithelial-mesenchymal transition changes in an air-liquid culture model. Thus, CSE-induced TROP2 is a possible biomarker for early changes in the epithelium of smokers, and ginsenoside Rb3 may serve as a therapeutic molecule, preventing the disruption of epithelial homeostasis in COPD.