High TROP2 Expression Research Articles

Identification of biomarker associated with Trop2 in breast cancer: implication for targeted therapy

PurposeTrop2, a cell membrane glycoprotein, is overexpressed in almost all epithelial cancers. This study aimed to explore the mutational characteristics and significance of Trop2 in breast cancer (BC).MethodsPatients diagnosed with BC (n = 77) were enrolled to investigate expression level and clinical characteristics of Trop2. Database of cBioPortal and Kaplan–Meier Plotter were used to evaluate the effects of Trop2 (TACSTD2) genomic ateration and mRNA expression levels on disease-free survival (DFS) and relapse-free survival (RFS), respectively. Based on next generation sequencing analysis, the Trop2 mutation characteristics of BC patients were deeply depicted. In addition, Trop2 expression, mutation and methylation signature associated with Trop2 mutations were analyzed.ResultsTrop2 mutation and high expression of Trop2 were predictive biomarker for shorter DFS and RFS in BC. The positive rate of Trop2 expression in these 77 BC patients was 96.1% (74/77). Based on the Trop2 expression level, the patients were classified into Trop2 negative group, medium expression group and high expression group. The mutation frequencies of MAP3K1, NOTCH2, PTEN and MAGI2 were significantly higher in Trop2 medium expression group than high expression group. Moreover, we investigated the effect of the Trop2 mutations on other genes, including co-expressed genes, differentially mutated genes, differentially expressed genes, gene methylation and phosphorylation. We found that MED8, DPH2, KDM4A, EBNA1BP2, USP1, IPO13, CGAS, PRKAA2, NCOA7, ASCC3 and ABRACL were differentially expressed, mutated and methylated between Trop2 mutation group and wild group.ConclusionMAP3K1, NOTCH2, PTEN and MAGI2 mutations were significantly different between Trop2 medium expression and Trop2 high expression BC patients. The effects of Trop2 mutation on the expression, variation, methylation, and phosphorylation of other genes were comprehensively revealed. High expression level of Trop2 and Trop2 mutation were predictive biomarker for poor prognosis and targeted therapy in BC.

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<0.0001). Immune infiltration analysis suggested that Trop2 expression was correlated with immune cell infiltration and the abundance (P<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]

Trophoblast Cell Surface Antigen 2 Expression in Thymic Carcinoma: Brief Report

IntroductionTrophoblast cell surface antigen 2 (TROP2) is a transmembrane glycoprotein overexpressed in various cancer types. Although TROP2-targeting therapy is currently attracting attention, little is known about TROP2 expression in thymic carcinoma. MethodsTROP2 gene expression in thymic epithelial tumors was analyzed using RNA-sequencing (RNA-seq) data for 122 cases obtained from The Cancer Genome Atlas. Immunohistochemistry (IHC) staining with anti-TROP2 antibody (SP295) was performed in 26 cases of thymic carcinoma tissues surgically resected at Juntendo University. ResultsRNA-seq data analysis from The Cancer Genome Atlas revealed that TACSTD2 (gene encoding TROP2) expression was significantly higher in thymic carcinoma than in thymoma (adjusted p = 6.64e-05). There was also a trend of increasing expression in the order of thymoma type B1, B2, B3, and thymic carcinoma. As for IHC in thymic carcinoma, TROP2 expression was localized to the membrane of cancer cells. Intensity 0, 1, and 2 was observed in six (23.1%), 11 (42.3%), and nine (34.6%) cases, respectively, leading to TROP2 positivity in 20 cases (76.9%). The median proportion of TROP2-positive tumor cells and the median H-score were 25.0% (range: 0%–100%) and 25.0 (range: 0–200), respectively. No relevant factors were identified in the analysis of TROP2 expression and patient background. Although not significant, high TROP2 expression (H-score ≥ 50) tended to be associated with shorter survival. ConclusionsTROP2 expression in thymic carcinoma was confirmed by both RNA-seq and IHC, with high expression observed in IHC for intensity (76.9%) and proportion. TROP2 could be a potential target in thymic carcinoma.

Abstract PS08-08: Updated efficacy and safety of SKB264 (MK-2870) for previously treated metastatic triple negative breast cancer (mTNBC) in Phase 2 study

Abstract Background: Patients (pts) with mTNBC have limited treatment options and poor prognosis. The estimated median overall survival (OS) of pts with mTNBC is 12 to 18 months (mo) after diagnosis. SKB264, an antibody drug conjugate (ADC) composed of an anti-TROP2 antibody coupled to a cytotoxic belotecan-derivative via a novel linker with an average Drug to Antibody Ratio (DAR) of 7.4, has shown promising anti-tumor activity and tolerable safety profile in pts with mTNBC (Yin, Y. et al. SABCS 2022). Here, we report the updated data from a Phase 2 expansion cohort for pts with mTNBC (NCT04152499). Methods: Pts with previously treated mTNBC were enrolled to receive SKB264 at 4 mg/kg Q2W or 5 mg/kg Q2W in a non-randomized manner until disease progression or unacceptable toxicity. Tumor assessment was performed every 8 weeks per RECIST v1.1 assessed by investigator. The primary objective was to assess objective response rate (ORR). Secondary objectives included DoR, PFS, and OS. The TROP2 expression was scored using the semi-quantitative H-score method, and a preliminary cutoff was set as 200. TROP2 expression and its association with anti-tumor activity were retrospectively analyzed. Results: At data cut-off date (May 05, 2023), 59 pts were enrolled (23 in 4 mg/kg, 36 in 5 mg/kg), and 88% (52 pts) had received ≥3 prior lines of therapy for metastatic disease. The median follow-up was 22.8 months (mo; 95% CI, 21.3-25.2). The ORR was 42.4% (25/59, 22 confirmed and 3 unconfirmed) and disease control rate (DCR) was 76.3% (45/59). The median duration of response (DoR) was 11.5 mo (range, 3.7 to 22.1+). Median PFS (mPFS) was 5.7 mo (95% Cl: 3.8, 9.1). Median OS (mOS) was 16.8 mo (95% Cl: 12.7, NE), while 12-mo and 24-mo OS rates were 65.0% and 39.5%, respectively. In the subset of pts with high TROP2 expression (H-score>200, N=32), ORR was 53.1% (including 3 complete response), mDoR was 11.1 mo (range, 3.7 to 22.1+), mPFS was 5.8 mo (95% Cl: 3.7, 13.3), mOS was not reached (95% Cl: 9.7, NE), while 12-mo and 24-mo OS rates were 65.3% and 57.3%, respectively. Treatment-related adverse events (TRAEs) of ≥ Grade 3 severity were reported in 57.6% (34/59) of pts. The most common ≥ Grade 3 TRAEs (≥ 10%) were neutrophil count decreased (25.4%), white blood cell count decreased (23.7%), anemia (22.0%) and platelet count decreased (16.9%). TRAEs leading to dose reduction and dose delay occurred in 13.6% (8/59) and 47.5% (28/59) of pts, respectively. Three pts discontinued treatment due to TRAEs (platelet count decreased, dry eye, anaphylactic shock). No cases of interstitial lung disease (ILD), neuropathy or grade ≥3 diarrhea were observed. Serious TRAEs were reported in 28.8% (17/59) of pts; no deaths associated with TRAEs were observed. Conclusions: The updated data continues to demonstrate that pts with heavily pretreated mTNBC could achieve durable response and a trend of long-term OS benefit from SKB264 treatment, along with a manageable safety profile. Higher response rate was seen in mTNBC pts with high TROP2 expression. A Phase 3 study of SKB264 vs. investigator’s choice of chemotherapy in 3L+ mTNBC (NCT05347134) and a Phase 2 study evaluating SKB264 as monotherapy or combination with anti-PD-L1 antibody in first-line setting (NCT05445908) are ongoing in China. Citation Format: Yongmei Yin, Xinhong Wu, Quchang Ouyang, Min Yan, Lihua Song, YunPeng Liu, Zhongsheng Tong, Cuizhi Geng, Ying Wang, Guohua Yu, Xiang Wang, Ying Cheng, Weihong Zhao, Xiaoping Jin, Yina Diao, Gesha Liu, Mengyu Yang, Yue Yang, Yalan Yang, Lian Lu, Junyou Ge, Jin Li, Qun Li. Updated efficacy and safety of SKB264 (MK-2870) for previously treated metastatic triple negative breast cancer (mTNBC) in Phase 2 study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS08-08.

Abstract 5819: An anti-TROP2-CPT113 ADC, exhibits potent targeted antitumor activity and favorable pharmacokinetic properties

Abstract Trophoblast cell surface antigen 2 (TROP2) is highly expressed in a number of epithelial cancer types and is considered to be a poor prognostic marker. We have developed an anti-TROP2 antibody-drug conjugate, DXC1002, that contains a potent inhibitor of DNA topoisomerase I payload (CPT113) attached to the antibody mainly in the Fab region via a unique hydrophilic CrossConju™ linker. The anti-tumor activities of DXC1002 were studied in various human cancer cell lines and xenograft mouse models and pharmacokinetic profile of DXC1002 were evaluated in cynomolgus monkeys and rats. DXC1002 demonstrated potent anti-tumor activity in TROP2 tumor cells of various expression levels in vitro, and at low dose of 1 mg/kg for one injection, in both high and moderate Trop2 expression xenograft models. In plasma stability studies, wherein DXC1002 was incubated in the plasma of five different species for 168 hours (7 days) at 37 oC, over 90% ADC was intact, exhibiting good stability of the CrossConju™ linker. Pharmacokinetic studies of DXC1002 in monkeys (TROP2 cross-species) and rats (non-TROP2 cross-species) showed half-lives of about 61.27 and 236.77 hours, respectively. Systemic clearance in monkey and rat was 0.41-0.67 and 0.279-0.309 mL/h/kg, respectively. The longer half-lives and slower clearance observed in rats the results offered a more direct assessment of the linker stability as target-mediated clearance played no role in rats. In summary, with the conjugation of a DNA topoisomerase I inhibitor payload to Trop2 antibody via the CrossConju™ linker, DXC1002 demonstrates remarkable anti-tumor properties and pharmacokinetic profile, with a potential to be further validated in clinical applications. Citation Format: Huihui Guo, Xiangfei Kong, Yong Du, Zhicang Ye, Yongxiang Chen, Zhixiang Guo, Lingli Zhang, Lu Bai, Junxiang Jia, Yunxia Zheng, Wei Zheng, Jun Zheng, Wenjun Li, Yuanyuan Huang, Zhongliang Fan, Mengmeng Liu, Binbin Chen, Meng Dai, Juan Wang, Miaomiao Chen, Qingliang Yang, Robert Y. Zhao. An anti-TROP2-CPT113 ADC, exhibits potent targeted antitumor activity and favorable pharmacokinetic properties [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5819.

High expression of Trop2 is associated with aggressive localized prostate cancer and is a candidate urinary biomarker

Distinguishing indolent from clinically significant localized prostate cancer is a major clinical challenge and influences clinical decision-making between treatment and active surveillance. The development of novel predictive biomarkers will help with risk stratification, and clinical decision-making, leading to a decrease in over or under-treatment of patients with prostate cancer. Here, we report that Trop2 is a prognostic tissue biomarker for clinically significant prostate cancer by utilizing the Canary Prostate Cancer Tissue Microarray (CPCTA) cohort composed of over 1100 patients from a multi-institutional study. We demonstrate that elevated Trop2 expression is correlated with worse clinical features including Gleason score, age, and pre-operative PSA levels. More importantly, we demonstrate that elevated Trop2 expression at radical prostatectomy predicts worse overall survival in men undergoing radical prostatectomy. Additionally, we detect shed Trop2 in urine from men with clinically significant prostate cancer. Our study identifies Trop2 as a novel tissue prognostic biomarker and a candidate non-invasive marker for prostate cancer.

High TROP2 expression as a poor prognosis factor for pancreatic cancer

High TROP2 expression as a poor prognosis factor for pancreatic cancer

Clinicopathologic Characteristics of Trop Family Proteins (Trop-2 and EpCAM) in Gastric Carcinoma.

Trop family proteins, including epithelial cell adhesion molecule (EpCAM) and Trop-2, have garnered attention as potential therapeutic and diagnostic targets for various malignancies. This study aimed to elucidate the clinicopathological significance of these proteins in gastric carcinoma (GC) and to reinforce their potential as biomarkers for patient stratification in targeted therapies. Immunohistochemical (IHC) analyses of EpCAM and Trop-2 were performed on GC and precancerous lesions, following rigorous orthogonal validation of the antibodies to ensure specificity and sensitivity. Strong membranous staining (3+) for Trop-2 was observed in 49.3% of the GC cases, whereas EpCAM was strongly expressed in almost all cases (93.2%), indicating its widespread expression in GC. A high Trop-2 expression level, characterized by an elevated H-score, was significantly associated with intestinal type by Lauren classification, gastric mucin type, presence of lymph node metastasis, human epidermal growth factor receptor 2-positivity, and Epstein-Barr virus (EBV)-positivity. Patients with a high Trop-2 expression level exhibited poorer survival outcomes on univariate and multivariate analyses. High EpCAM expression levels were prevalent in differentiated histologic type, microsatellite instability-high, and EBV-negative cancer, and were correlated with high densities of CD3 and CD8 T cells and elevated combined positive score for programmed death-ligand 1. These results highlight the differential expression of Trop-2 and EpCAM and their prognostic implications in GC. The use of meticulously validated antibodies ensured the reliability of our IHC data, thereby offering a robust foundation for future therapeutic strategies targeting Trop family members in GC.

ImmunoPET imaging of Trop2 expression in solid tumors with nanobody tracers.

The high expression of the transmembrane glycoprotein trophoblast cell-surface antigen 2 (Trop2) was strongly associated with the progression of solid tumors, including pancreatic and gastric cancers. Our study aimed to construct Trop2-specific immuno-positron emission tomography (immunoPET) probes and assess the diagnostic abilities in preclinical pancreatic and gastric cancer models. The expression of Trop2 in pancreatic cancer was determined by single-cell sequencing and immunohistochemistry on tissue microarray (TMA). Flow cytometry was used to screen the expression of Trop2 in pancreatic cancer cell lines. Two nanobodies (i.e., RTD98 and RTD01) targeting Trop2 were developed and labeled with gallium-68 (68Ga, T1/2 = 1.1 h) to construct immunoPET imaging probes. The agents were researched in cell-derived pancreatic and patient-derived gastric cancer models expressing varying Trop2. Single-cell sequencing results showed high expression of Trop2 in pancreatic ductal cells as well as acinar cells and immunohistochemical staining of TMA from pancreatic cancers showed significantly higher expression of Trop2 in cancerous than in paracancerous tissues. ImmunoPET utilizing [68Ga]Ga-NOTA-RTD98 could clearly delineate subcutaneous tumors, both in cell-derived pancreatic cancer models and patient-derived gastric cancer models, superior to imaging using [18F]-FDG or a non-specific probe [68Ga]Ga-NOTA-RTD161. Another probe with improved pharmacokinetics targeting Trop2, [68Ga]Ga-NOTA-RTD01, was further prepared and showed advantageous diagnostic capabilities in preclinical pancreatic cancer models. In the work, we reported two nanobody tracers targeting human Trop2 which may facilitate better use of Trop2-targeted therapeutics by noninvasively displaying expression dynamics of the target.

TROP2 expression and response to immune checkpoint inhibition in patients with advanced non-small cell lung cancer.

9040 Background: Despite anti-monoclonal antibodies targeting programmed cell death-1 (PD-1) or its ligand PD-L1 revolution, most patients (pts) with advanced NSCLC displayed primary resistance to PD1/PD-L1 blockade. Identifying targetable alterations involved in resistance represent a promising approach to improve immunotherapy efficacy. TROP2 expression is associated with a poor prognosis in NSCLC, and offers a promising target for treatment with the development of new antibody drug conjugate. TROP2 has been suggested to play a role in innate immunity response, but, it's unclear whether TROP2 expression by tumor cells is detrimental specifically in the context of PD1/PD-L1 blockade. The aim of our study was to investigate the the role of TROP2 expression in outcome of NSCLC pts treated with ICI. Methods: We analyzed the largest NSCLC gene expression data set worldwide including the whole-transcriptome profile of 891 pre-treatment tumors from POPLAR and OAK trials, two randomized studies assessing the efficacy of atezolizumab versus docetaxel in NSCLC. We complemented this transcriptional approach with multiplex IF and digital pathology analysis to confirm our findings at the protein level We investigated whether a non-invasive approach focusing on the level of plasma levels of circulating TROP2 may be relevant to predict efficacy of ICI. Results: The PFS of pts with high expression of TROP2 was significantly lower than in pts with low expression 2.5 vs 4.1 months, p < 0.001. Strikingly, high TROP2 expression was also associated with lower clinical benefit rate 15% vs 28%, p = 0.009 and worse overall survival (OS) 12.6 vs 16.3 months, p = 0.007 When adjusting for covariates such as histological subtype, TLS signature, PD-L1 expression, TROP2 remained independently associated with PFS and OS. None of these correlations were observed in the docetaxel arm, suggesting a predictive value of TROP2 gene expression specifically for response to ICI. By using a deconvolution approach, we also observed that TROP2-high tumors were characterized by a significant lowest expression of genes specific to immune populations (T effector memory cells,Th17 cells). Multiplex IF on an independent cohort 53 NSCLC tumors confirmed the correlation between high TROP2, microenvironment features and poor response to PD1 inhibition. Analysis of circulating plasma levels of TROP2 in 97 NSCLC patients revealed a strong correlation with expression in tumor tissue. High plasma levels of circulating TROP2 was also significantly associated with worse ORR, PFS and OS on treatment with PD1/PDL1 antagonist. Conclusions: Our study revealed that TROP2 expression by tumor cells in NSCLC is associated with worse outcome in patients with NSCLC independently of PDL1 expression. Targeting TROP2 in combination with ICI may represent a promising strategy to improve ICI efficacy in pts with TROP2-high NSCLC.

Trop-2 is a ubiquitous and promising target in pancreatic adenocarcinoma

BackgroundTrop-2 is overexpressed in tumor cells of various cancers, including pancreatic ductal adenocarcinoma (PDAC), and has emerged as a potent therapeutic target. We evaluated Trop-2 expression both at the transcriptomic and protein levels, and its correlation with tumor features and patients’ outcomes in a large cohort of PDAC. MethodsWe included patients undergoing pancreatic resection for PDAC in 5 academic hospitals in France and Belgium. Transcriptomic profiles were obtained from FFPE tissue samples, with paired primary -25and metastatic lesions when available. Protein expression was evaluated by immunohistochemistry (IHC) using tissue micro-arrays. Results495 patients (male 54%, median age 63 years) were included between 1996 and 2012. Trop-2 mRNA expression was significantly associated to tumor cellularity, but no association with survival nor with any clinical or pathological features was observed, with tumor cells showing an overall high expression among every subgroup. Trop-2 mRNA expression was maintained between primary and metastatic lesion in all 26 paired samples evaluated. In 50 tumors assessed by IHC, 30%, 68% and 2% harbored a high, medium, or low Trop-2 expression score, respectively. Trop-2 staining was significantly associated to mRNA expression, but not to survival or any pathological features. ConclusionsOur results suggest Trop-2 overexpression as a ubiquitous marker of PDAC tumor cells and thus a promising therapeutic target to evaluate in these patients.

Abstract OT1-03-02: Efficacy and safety of SKB264 for previously treated metastatic triple negative breast cancer in Phase 2 study

Abstract Background: The therapeutic options for patients (pts) with previously treated metastatic TNBC are limited compared with other breast cancer subtypes. SKB264 is an antibody drug conjugate (ADC) composed of an anti-TROP2 antibody coupled to the cytotoxic belotecan-derivative via a novel linker. Here, we present results from a Phase 2 expansion cohort for pts with mTNBC (NCT04152499). Methods: Pts with previously treated mTNBC were enrolled to receive SKB264 4 mg/kg Q2W or 5 mg/kg Q2W in a non-randomized fashion until disease progression/unacceptable toxicity. The assessment for tumor response was performed every 8 weeks per RECIST v1.1 assessed by investigator. The TROP2 expression was scored using the semi-quantitative H-score method, and cut off point was set to 200. TROP2 expression and its association with anti-tumor activity was retrospectively analyzed. Results: At data cut-off date (May 15, 2022), 59 pts were enrolled (23 in 4 mg/kg, 36 in 5 mg/kg), 88% of them (52 pts) had received ≥3 prior therapies for metastatic disease. Among 53 patients with tissue available for TROP2 testing, 29 patients (55%) had TROP2 high (H-score >200-300) tumors. The median follow up was 9.6 months. Of 55 pts (21 in 4 mg/kg and 34 in 5 mg/kg) evaluable for response assessment (≥1 on-study scan), the confirmed ORR (cORR) was 40% (22/55) and disease control rate (PR+CR+SD) was 80% (44/55). The cORR was 55% (16/29) in the subset of patients with high TROP2 expression. The median duration of response (DoR) was not reached with range from 1.0+ to 11.0+ months and the 6-month DoR rate was 82%. Median PFS was 5.7 months (95% Cl: 3.9, 7.6). Treatment-related adverse events (TRAEs) of ≥ Grade 3 were reported in 55.9% (33/59) of pts. The most common ≥ Grade 3 TRAEs (≥ 10%) were neutrophil count decreased (23.7%), anemia (20.3%) and platelet count decreased (16.9%). TRAEs led to dose reduction in 15.2% (9/59) of pts and to discontinuation in 6.8% (4/59) of pts. No treatment-related AEs leading to death or interstitial lung disease (ILD) were reported. Safety and anti-tumor activities of SKB264 by dose level will be presented. Conclusions: SKB264 demonstrates a manageable safety profile and promising antitumor activity in pts with heavily pretreated mTNBC. SKB264 toxicity was mainly hematologic. A Phase 3 study of SKB264 vs investigator selected chemo alone in pts with locally advanced inoperable or metastatic TNBC was initiated (NCT05347134). Citation Format: Yongmei Yin, Xinhong Wu, Quchang Ouyang, Min Yan, Lihua Song, YunPeng Liu, Zhongsheng Tong, Cuizhi Geng, Ying Wang, Guohua Yu, Xiang Wang, Ying Cheng, Weihong Zhao, Qun Li, Yina Diao, Gesha Liu, Junyou Ge, Jin Li. Efficacy and safety of SKB264 for previously treated metastatic triple negative breast cancer in Phase 2 study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-03-02.

Abstract GS1-11: Sacituzumab Govitecan (SG) vs Treatment of Physician’s Choice (TPC): Efficacy by Trop-2 Expression in the TROPiCS-02 Study of Patients (Pts) With HR+/HER2– Metastatic Breast Cancer (mBC)

Abstract Background: HR+/HER2– mBC, the most common subset of breast cancer, is treated with sequential endocrine therapy + targeted agents followed by sequential single-agent chemotherapy (CT), with increasingly shorter benefit duration with each subsequent treatment. High Trop-2 expression is observed in breast cancer regardless of subtype. SG is a Trop-2-directed antibody-drug conjugate approved for pre-treated metastatic triple-negative breast cancer. In the phase 3 TROPiCS-02 study, SG showed both significant progression-free survival (PFS) benefit (HR, 0.66; P<0.001; median 5.5 vs 4.0 mo; JCO 2022) at the primary analysis and overall survival (OS) benefit (median 14.4 vs 11.2 mo; HR, 0.79; P=0.02; ESMO 2022) at the 2nd planned interim OS analysis vs TPC in pretreated HR+/HER2- mBC. Here we compare efficacy outcomes for SG and TPC by Trop-2 expression. Methods: Eligible pts had HR+/HER2- locally recurrent inoperable or mBC; received ≥1 prior taxane, endocrine therapy, a CDK4/6 inhibitor; and received 2-4 prior CT regimens for mBC. Pts were randomized 1:1 to receive SG (10 mg/kg IV on d 1 and 8, every 21 d) or TPC (eribulin, gemcitabine, capecitabine, or vinorelbine) until disease progression or unacceptable toxicity. The primary endpoint was PFS by independent review per RECIST v1.1; OS and objective response rate (ORR) were key secondary endpoints. ORR was assessed by blinded independent central review per RECIST v1.1. Membrane Trop-2 expression on archival tumor tissue was assessed by immunohistochemistry and expressed as a histochemical score (H-score; range, 0-300); efficacy outcomes were assessed in H-score <100 and ≥100 groups. The H-score <100 group was further divided into H-score ≤10 and >10- <100 subgroups to assess the activity of SG in pts with very low Trop-2 expression. Results: Data cut-off was January 3, 2022 for PFS (median follow-up, 10.2 mo) and July 1, 2022 for OS (median follow-up, 12.5 mo). In total, 543 pts were randomized to receive SG (n=272) vs TPC (n=271). Pts had a median of 3 prior CT regimens for mBC; 95% had visceral metastases. There were 238 (88%) vs 224 (83%) Trop-2-evaluable pts in the SG vs TPC groups, respectively; of these, 95% had tumors with Trop-2 H-score >0. Of Trop-2-evaluable pts, 192 (42%) and 270 (58%) had H-scores <100 and ≥100, respectively. Demographics and baseline characteristics were generally consistent across H-score groups. PFS and OS benefit was observed for SG vs TPC across both Trop-2 groups (Table). Median PFS was 5.3 vs 4.0 mo (HR, 0.77; 95% CI, 0.54-1.09) and 6.4 vs 4.1 mo (HR, 0.60; 95% CI, 0.44-0.81) in the H-score <100 and ≥100 groups; median OS was 14.6 vs 11.3 mo (HR, 0.75; 95% CI, 0.54-1.04) and 14.4 vs 11.2 mo (HR, 0.83; 95% CI, 0.62-1.11), respectively. Disease response was observed in the 34 pts with H-score ≤10 who received SG. In pts who received SG, those with H-score ≤10, >10- <100, and ≥100 had ORRs of 24%, 18%, and 23%, respectively. The safety profile for SG by Trop-2 H-score was consistent with previous reports. Conclusions: In this TROPiCS-02 post-hoc analysis, improved efficacy with SG vs TPC was observed regardless of Trop-2 expression, and there was no clear level of Trop-2 expression at which a better treatment effect for SG was observed. These results support SG as an effective novel treatment option for patients with pretreated, endocrine-resistant HR+/HER2- mBC, and reinforce that Trop-2 testing is not required for SG treatment. Table Citation Format: Hope Rugo, Aditya Bardia, Frederik Marmé, Javier Cortés, Peter Schmid, Delphine Loirat, Olivier Trédan, Eva Ciruelos, Florence Dalenc, Patricia Gómez Pardo, Komal Jhaveri, Monica Motwani, Oh Kyu Yoon, Hao Wang, Wendy Verret, Sara Tolaney. Sacituzumab Govitecan (SG) vs Treatment of Physician’s Choice (TPC): Efficacy by Trop-2 Expression in the TROPiCS-02 Study of Patients (Pts) With HR+/HER2– Metastatic Breast Cancer (mBC) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS1-11.

Abstract P4-07-12: Development of Triple-negative breast cancer (TNBC) syngeneic models and TROP2-directed antibody-drug conjugate (ADC) surrogate to model therapeutic combinations

Abstract Background: Sacituzumab govitecan (SG, Trodelvy®) is a human trophoblast cell surface antigen 2 (TROP-2) directed antibody drug conjugate (ADC) coupled to an active form of irinotecan (SN-38) via our novel hydrolyzable linker (CL2A). SG is the only FDA-approved ADC treatment for TNBC patients in the second-line setting. TROP-2 is a transmembrane protein encoded by the tumor-associated calcium signal transducer 2 (TACSTD2) gene and highly expressed in TNBC, an aggressive type of cancer accounting for approximately 15% of all breast cancers. TROP-2 overexpression is associated with poor survival and relapse, but its biological function in TNBC remains poorly understood. Hypothesis/rationale: To better understand TROP-2 and TROP-2-directed ADC biology, we developed and characterized TROP2high vs TROP2low TNBC syngeneic tumors and an SG surrogate directed to murine TROP-2. Experimental design: We established 2 syngeneic TNBC models with differential TROP-2 expression: 4T1 cells were flow sorted into high (>95%) vs low (< 7%) TROP-2 expressors and EMT6 cells were transduced with a murine TACSTD2-encoding lentivirus. Balb/c mice were subcutaneously implanted with 0.5 × 10 E6 TROP-2high, TROP-2low, or parental tumor cells (4T1 or EMT6). Tumor immunophenotyping and transcriptomic analyses were performed 15 and 24 days after implantation. An SG mouse surrogate was engineered to mimic SG, using an anti-TROP-2 antibody (Rab64) that cross-reacts with human and murine TROP-2 covalently attached to SN-38 by the CL2A linker. SG surrogate activity was characterized in vitro and in 4T1 syngeneic models. Results: SG surrogate demonstrated high affinity for human and mouse TROP-2 (KD=1.1 and 1.4 nM, respectively) with SN-38 release rates and PK similar to that of SG. Flow cytometry analysis after bulk cell sorting of 4T1 or lentivirus transduction of EMT6 confirmed high TROP2 expression after at least 3 in vitro passages. Fifteen days after subcutaneous implantation, flow cytometry analysis of tumor single-cell suspensions revealed significant differences in immune infiltrates between 4T1-derived tumor groups (n=5/group; mean percentages in TROP2high vs TROP2low 4T1-derived tumors of cells expressing CD45: 65% vs 10%, P < 0.0001; CD8: 5.5% vs 1%, P = 0.0033; CD4: 22% vs 4%, P = 0.0055; macrophages: 12.5% vs 2.5%, P = 0.0002; myeloid cells: 52% vs 75%, P = 0.0066). In addition, TROP2high 4T1-derived tumors were smaller and had significantly less necrosis than TROP2low and unsorted 4T1-derived tumors 25 days after implantation. Finally, transcriptomics analyses of TROP2high vs TROP2low 4T1-derived tumors demonstrated the association of TACSTD2 expression levels with regulation of distinct molecular pathways. Conclusion: Syngeneic tumors derived from 4T1 cells with differential TROP2 expression levels are associated with differential cellular states and tumor microenvironment composition. In contrast, no significant phenotypic changes were observed in tumors derived from TACSTD2-transduced compared with mock-transduced EMT6 cells. Taken together, these results suggest that expression of the TACSTD2 gene is associated with, but not causative of, different tumor phenotypic states. Additional studies to investigate TROP-2 expression as a correlative marker of patient prognosis and the antitumor immune response are warranted. The effects of in vivo treatment with an SG surrogate on 4T1 tumor growth and immune phenotype will be discussed at the time of the presentation. Citation Format: Chih-Chien Chou, Jordan Kardos, Becky Yang, Jessica Orf, Rutwij Dave, Yurong Lai, Chingwei V. Lee, Giuseppe A. Papalia, Kelli Boyd, Lauri Diehl, Nathalie Scholler. Development of Triple-negative breast cancer (TNBC) syngeneic models and TROP2-directed antibody-drug conjugate (ADC) surrogate to model therapeutic combinations [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-12.

Abstract 507: Trop-2 expression in triple-negative breast cancer according to histological subtype: correlations with tumor infiltrating lymphocytes (TILs) and survival

Abstract Background: Trop-2 is a transmembrane calcium signal transducer highly expressed in multiple solid tumors including breast cancer. Limited data exist about associations between Trop-2 protein expression, clinicopathological characteristics and outcome in triple-negative breast cancers (TNBC). Given the approval of sacituzumab govitecan in unselected TNBC, its evaluation in other breast cancer settings and the emergence of other Trop-2 targeted antibody-drug conjugates, Trop-2 emerges as an important drug target in solid tumors. Methods: Trop-2-expression of patients with TNBC diagnosed between 2000-2017 at UZ Leuven was determined with IHC (ab227689, Abcam) (continuous and categorical variables, high 201-300, medium 100-200 and low <100 H-score). Associations of Trop-2-expression with age, BMI, germline BRCA status, tumor grade and size, histological subtype, lymphovascular invasion (LVI), presence of DCIS, nodal status, stromal TILs, androgen receptor (AR), standardized mitotic index, and outcome (invasive disease-free survival (iDFS), distant recurrence-free survival (D-RFi) and breast cancer-specific survival (BCSS)) were assessed. Associations with continuous variables were assessed by the Spearman correlation coefficient (ρ). Group differences were assessed by the Kruskal Wallis test for multiple groups or Mann-Whitney U test for two groups. Cox proportional hazards models were used to assess the association between Trop-2 expression and outcome. Results: Total of 658 patients with a median age at diagnosis of 53y (range 22-89y) were included, with median follow-up 9.6y. Low, medium and high Trop-2 expression was seen in 58.2%, 25.3% and 16.5% of cases. AR was positive in 25.5% of cases (10%-cutoff). Highest Trop-2 expression was observed in tumors with apocrine histology (median 180 score), and lowest expression in tumors with metaplastic histology (median 45 score) (p<.001). Higher Trop-2 expression was correlated with higher AR expression (10%-cutoff) (p=0.009), more presence of nodal involvement (p=0.016), associated DCIS (p=0.004) and LVI (p=0.006). Trop-2 expression was not associated with pathological complete response (pCR) observed in 22 of 64 patients treated with neoadjuvant chemotherapy (p=0.96). There was an iDFS events frequency of 199 out of 658 (30.2%). There was no correlation between Trop-2 expression and sTILs or outcome. Conclusion: In patients with TNBC in a large tertiary center, higher Trop-2 expression was correlated with apocrine histology, higher AR expression, more associated DCIS, more LVI and nodal involvement. There was no correlation between Trop-2 expression and sTILs or outcome. Citation Format: Hava Izci, Kevin Punie, Lise Waumans, Annouschka Laenen, Hans Wildiers, Freija Verdoodt, Christine Desmedt, Jan Ardui, Ann Smeets, Sileny Han, Ines Nevelsteen, Patrick Neven, Giuseppe Floris. Trop-2 expression in triple-negative breast cancer according to histological subtype: correlations with tumor infiltrating lymphocytes (TILs) and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 507.

Trop-2 in Upper Tract Urothelial Carcinoma.

Trophoblast cell surface antigen 2 (Trop-2, encoded by TACSTD2) is the target protein of sacituzumab govitecan, a novel antibody-drug conjugate for locally advanced or metastatic urothelial carcinoma. However, the expression status of Trop-2 in upper tract urothelial carcinoma (UTUC) remains unclear. We performed immunohistochemical analysis of 99 UTUC samples to evaluate the expression status of Trop-2 in patients with UTUC and analyze its association with clinical outcomes. Trop-2 was positive in 94 of the 99 UTUC samples, and high Trop-2 expression was associated with favorable progression-free survival (PFS) and cancer-specific survival (p = 0.0011, 0.0046). Multivariate analysis identified high Trop-2 expression as an independent predictor of favorable PFS (all cases, p = 0.045; high-risk group (pT3≤ or presence of lymphovascular invasion or lymph node metastasis), p = 0.014). Gene expression analysis using RNA sequencing data from 72 UTUC samples demonstrated the association between high TACSTD2 expression and favorable PFS (all cases, p = 0.069; high-risk group, p = 0.029). In conclusion, we demonstrated that Trop-2 is widely expressed in UTUC. Although high Trop-2 expression was a favorable prognostic factor in UTUC, its widespread expression suggests that sacituzumab govitecan may be effective for a wide range of UTUC.

Abstract P4-07-16: Correlation of Trop-2 expression with clinicopathological characteristics and outcome in triple-negative breast cancer (TNBC)

Abstract Purpose Trophoblast cell-surface antigen-2 (Trop-2) is a transmembrane calcium signal transducer highly expressed in multiple solid tumors including breast cancer. Trop-2 overexpression has been associated with poor survival, but limited data exist about the association between Trop-2 expression, clinicopathological characteristics and outcome in patients with TNBC. Given the approval of sacituzumab govitecan in unselected TNBC and its evaluation in other breast cancer settings, Trop-2 emerges as an important target for antibody-drug conjugates. Methods We included 470 patients with TNBC, treated with upfront surgery or upfront chemotherapy at the University Hospitals Leuven from 2000-2017. Trop-2 expression was determined with IHC (ab227689, Abcam) on whole slide tumor sections from resection specimens (upfront surgery group) or core needle-biopsy (upfront chemotherapy group) and assessed as continuous (H-score 0-300) and categorical (high 200-300, medium 100-200 and low <100) variables. Stromal tumor infiltrating lymphocytes (sTIL; low, intermediate and high), mitotic score and androgen receptor (AR) expression (10%-cutoff) were scored. We assessed associations between Trop-2 expression and age, BMI (lean 18-25 (low), overweight 25-30 and obese ≥30 (high)), tumor grade and size, histological subtype, lymphovascular invasion (LVI), presence of DCIS, nodal status, sTILs, AR, standardized mitotic index and outcome (distant recurrence-free survival (DRFI), invasive disease-free survival (IDFS) and breast cancer-specific survival (BCSS)). Associations between continuous variables were assessed by the Spearman correlation coefficient (ρ). Cox proportional hazards models were used to assess the association between Trop-2 expression of tumor characteristics and outcome. Results are presented as hazard ratios (HR) with incremental increase of continuous Trop-2. Results The median age at diagnosis was 51y (range 22-85y) and the median follow-up 9.6y. For the group with upfront surgery (N=406), AR was positive in 21.5% of cases. Low, medium and high Trop-2 expression was seen in 55.7%, 23.6% and 20.7%. Higher Trop-2 expression was correlated with higher age at diagnosis (ρ=0.13, p=0.009). LVI was more frequent in Trop-2-high (39%) compared to Trop-2-medium (19%) or -low (20%) (p=0.004). Patients in Trop-2-high subgroup had more nodal involvement (45%) compared to Trop-2-medium (29%) (p=0.03). There was no correlation between Trop-2 expression with sTILs, BMI, AR or outcome. However, we found significantly improved DRFI and BCSS with increasing Trop-2 expression for the BMI-low subgroup (HR=0.95 [95%C.I. 0.89;0.99], p=0.02 and HR=0.95 [95%C.I. 0.89;0.99], p=0.04). For the group with upfront chemotherapy (N=64), AR was positive in 28.1% of cases. Low, medium and high Trop-2 expression was seen in 45.3%, 53.1% and 1.6% of cases. No difference was seen for Trop-2 expression in patients with pathological complete response (N=22) and residual disease (N=42) (median 100 vs 100 H-score, p=0.96). Higher Trop-2 expression was seen in lean compared to obese patients (100 vs 50, p=0.03). Conclusion In patients with TNBC treated with upfront surgery, higher Trop-2 expression was correlated with older age, more LVI and nodal involvement. There was overall no correlation between Trop-2 expression with sTILs, AR or outcome. Limited numbers of events warrant caution in interpretation. Citation Format: Hava Izci, Kevin Punie, Lise Waumans, Annouschka Laenen, Hans Wildiers, Freija Verdoodt, Christine Desmedt, Jan Ardui, Ann Smeets, Sileny Han, Ines Nevelsteen, Patrick Neven, Giuseppe Floris. Correlation of Trop-2 expression with clinicopathological characteristics and outcome in triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-07-16.

Impact of Spatially Heterogeneous Trop-2 Expression on Prognosis in Oral Squamous Cell Carcinoma.

Oral cancer often presents with aggressive behavior and a high risk of recurrence and metastasis. For oral squamous cell carcinoma (OSCC), which is the most frequent histological subtype, therapy strategies include surgery, radiation therapy, chemotherapy, immune checkpoint inhibitors, and EGFR inhibitors. Recently, a Trop-2 antibody-drug conjugate (ADC) has been approved in the United States of America for the treatment of advanced triple-negative breast cancer. However, this ADC has also been tested in other solid tumors including head & neck squamous cell carcinoma. The prognostic impact of Trop-2 has already been reported for several cancers. We studied the prognostic influence of Trop-2 protein expression on OSCC patients’ survival. The cohort comprised n = 229 OSCC patients with available archived tumor tissue and corresponding non-neoplastic oral mucosa tissue. Using immunohistochemistry, we investigated Trop-2 expression in both the central and peripheral regions of each tumor and in corresponding non-neoplastic oral mucosa. In patients suffering from OSCC with combined high central and low peripheral Trop-2 expression, five-year overall survival (OS) was 41.2%, whereas 55.6% of OSCC patients who presented lower central and/or higher peripheral tumoral Trop-2 expression were alive after five years (p = 0.075). In multivariate Cox regression, the expression pattern of high central tumoral and lower peripheral Trop-2 expression was significantly correlated with impaired OS (HR = 1.802, 95%-CI: 1.134–2.864; p = 0.013) and recurrence-free survival (RFS) (HR = 1.633, 95%-CI: 1.042–2.560; p = 0.033), respectively, when adjusting for co-variables. Hence, Trop-2 may serve as an independent prognostic biomarker in OSCC. In subsequent studies, the pathophysiological meaning of downregulated Trop-2 expression in the OSCC periphery has to be analyzed.

Prognostic Significance of Trophoblastic Cell Surface Protein 2 (Trop2) Expression in Breast Cancer and Relation to Microvascular Density

Background: The expression of trophoblastic cell surface protein 2 (Trop2) has been correlated with aggressive behavior in multiple malignant neoplasms. Moreover, it is a promising therapeutic target for several malignancies. However, data on the prognostic significance of Trop2 in breast cancer is insufficient. The current work aimed to study the prognostic significance of Trop2 expression in breast cancer and its correlation with microvascular density (MVD). Patients and Methods: Immunohistochemical expression of Trop2 was assessed in 70 cases of breast cancer and its relation to clinicopathological parameters, MVD (as assessed by CD34 immunostaining) and patient’s survival was evaluated. Results: High Trop2 expression was detected in 44 cases (62.9%) of the studied cases. The expression of Trop2 was significantly related to tumor size, lymph node stage, lymphovascular invasion, tumor grade and high Ki67 index (P<0.05). Moreover, the expression of Trop2 was significantly higher in triple-negative breast carcinoma (TNBC) than other molecular subtypes (P=0.015). Additionally, Trop2 expression was significantly correlated to MVD (r= 0.845). Both overall survival and disease-free survival were significantly shorter in the high Trop2 group than low Trop2 group (P=0.008, 0.021), respectively. Conclusion: Trop2 can be considered as a poor prognostic marker and potential therapeutic target for breast cancer, mainly the triple-negative subtype. Since Trop2 expression was significantly correlated to MVD, we speculate that enhancement of angiogenesis could be one of the mechanisms involved in Trop2 induced tumor invasion and metastasis.

Trop2 Expression in Extramammary Paget's Disease and Normal Skin.

Extramammary Paget’s disease (EMPD) is a rare skin cancer arising in the apocrine gland-rich areas. Most EMPD tumors are dormant, but metastatic lesions are associated with poor outcomes owing to the lack of effective systemic therapies. Trophoblast cell surface antigen 2 (Trop2), a surface glycoprotein, has drawn attention as a potential therapeutic target for solid tumors. Sacituzumab govitecan, an antibody–drug conjugate of Trop2, has recently entered clinical use for the treatment of various solid cancers. However, little is known about the role of Trop2 in EMPD. In this study, we immunohistochemically examined Trop2 expression in 116 EMPD tissue samples and 10 normal skin tissues. In normal skin, Trop2 was expressed in the epidermal keratinocytes, inner root sheaths, and infundibulum/isthmus epithelium of hair follicles, eccrine/apocrine glands, and sebaceous glands. Most EMPD tissues exhibited homogeneous and strong Trop2 expression, and high Trop2 expression was significantly associated with worse disease-free survival (p = 0.0343). These results suggest the potential use of Trop2-targeted therapy for EMPD and improve our understanding of the skin-related adverse effects of current Trop2-targeted therapies such as sacituzumab govitecan.