Trop2 Protein Research Articles

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

Human trophoblast cell surface antigen 2 (Trop-2) is a protein highly expressed in urothelial cancer (UC). Sacituzumab govitecan (SG) is a Trop-2-directed antibody drug conjugate with a hydrolysable linker and a potent SN-38 payload. This study explored Trop-2 expression in tumors treated with SG in cohorts 1 to 3 (C1-3) from the TROPHY-U-01 study and evaluated whether efficacy was associated with Trop-2 expression. TROPHY-U-01 (NCT03547973) is an open-label phase II study that assessed the efficacy and safety of SG (alone or in combinations) in patients with unresectable locally advanced or metastatic UC (mUC). Archival tumor samples collected at enrollment for C1-3 were analyzed for Trop-2 membrane expression by considering histological scores (H-scores; scale 0-300) and the percentage of membrane positive tumor cells at low magnification (4×). The association of Trop-2 with clinical endpoints [objective response rate (ORR), progression-free survival (PFS), and overall survival (OS)] was evaluated. In C1-3, tissue was collected from 158 (82%) of 192 treated patients, and 146 (76%) had evaluable Trop-2 data. Trop-2 was highly expressed in tumor samples. The median [interquartile range (IQR)] Trop-2 H-score was 215 (180-246), and the median (IQR) percentage of membrane positive tumor cells was 91% (80-98). Trop-2 expression at any level was observed in 98% of patients. Furthermore, ORR, PFS, and OS benefits were observed across all Trop-2 expression levels. Trop-2 protein is highly expressed in UC, as confirmed by examining tumors from patients enrolled in the TROPHY-U-01 trial. The results indicate that SG demonstrates efficacy in mUC across Trop-2 expression levels.

Efficacy and Safety of Sacituzumab Govitecan in Patients With Advanced Solid Tumors (TROPiCS-03): Analysis in Patients With Advanced Endometrial Cancer.

Patients with advanced endometrial cancer (EC) who progress on or after platinum-based therapy and immunotherapy have poor prognosis. We report efficacy and safety of sacituzumab govitecan (SG), a trophoblast cell-surface antigen 2 (Trop-2)-directed antibody-drug conjugate, in patients with advanced EC. TROPiCS-03 (ClinicalTrials.gov identifier: NCT03964727) is a multicohort, open-label, phase II basket study in patients with metastatic solid tumors. Eligible patients in the EC cohort received SG 10 mg/kg once on days 1 and 8 every 3 weeks. Primary end point was objective response rate (ORR) by investigator's assessment per RECIST v1.1. Secondary end points included clinical benefit rate (CBR; complete and partial response, and stable disease ≥6 months), duration of response (DOR), and progression-free survival (PFS) per investigator assessment, overall survival, and safety. Trop-2 expression of archival or baseline tumor specimens was analyzed by immunohistochemistry. At data extraction date, 41 patients were enrolled. Median follow-up was 5.8 months (range, 0.7-19.3); median previous therapies was three (range, 1-6); and 85% of patients received previous chemotherapy and immunotherapy. ORR was 22% (95% CI, 11 to 38); CBR was 32% (95% CI, 18 to 48). Median DOR was 8.8 months (95% CI, 2.8 to not estimable); median PFS was 4.8 months (95% CI, 2.8 to 9.8). Trop-2 exploratory analysis was conducted retrospectively for 39 patients. Tumor Trop-2 protein was highly expressed in EC, showing limited correlation with efficacy. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 73% of patients. Study drug discontinuation due to TRAEs was 5%. Two deaths occurred, deemed unrelated to SG. Findings from TROPiCS-03 showed encouraging efficacy of SG with a manageable toxicity profile in a heavily pretreated population with advanced EC. Safety findings were consistent with the known SG safety profile.

Preclinical evidence for the use of anti-Trop-2 antibody-drug conjugate Sacituzumab govitecan in cerebral metastasized castration-resistant prostate cancer.

Improved survival rates have been observed in castration-resistant prostate cancer (CRPC) due to advancements in treatment options. However, individuals with brain metastases still have limited therapeutic options and an unfavorable prognosis. Therefore, there is an urgent need to explore new therapeutic avenues, such as antibody-drug conjugates (ADCs), which have demonstrated significant clinical activity against active brain metastases in solid tumors. Our objective was to determine the expression levels of the ADC targets Trop-2 and NECTIN-4 in cerebral metastasized CRPC (mCRPC). Immunohistochemical staining of Trop-2 and NECTIN-4 with evaluation of H-score was performed in CRPC brain metastases (n = 31). Additionally, we examined Trop-2 protein expression in prostate cancer cell lines and studied their responsiveness to the anti-Trop-2 ADC Sacituzumab govitecan (SG) invitro. Our analysis revealed that most patients exhibited moderate to strong Trop-2 expression [n = 27/31 with H-score ≥100, median H-score 220 (IQR 180-280)], while NECTIN-4 was absent in all cerebral metastases. Mechanistically, we demonstrated that the efficacy of SG depends on Trop-2 expression levels invitro. Overexpression of Trop-2 in Trop-2-negative PC-3 cells led to sensitization to SG, whereas CRISPR-Cas9-mediated knockdown of Trop-2 in Trop-2-expressing DU-145 cells conferred resistance to SG. The substantial expression of Trop-2 in cerebral metastases, along with our preclinical invitro results, supports the efficacy of SG in treating cerebral mCRPC. Thus, our results extend the understanding of the potential of ADCs in prostate cancer treatment and provide an additional treatment strategy for the challenging subset of patients with cerebral metastases.

Abstract PO3-13-11: Quantitative Multiplex Immunofluorescence Assay for TROP2 and HER2 Expression in Breast Cancer: Towards Guiding Patient Selection for Antibody Drug Conjugate Therapies

Abstract Emerging antibody drug conjugate (ADC) therapies targeting human trophoblast cell-surface antigen (TROP2) and human epidermal growth factor receptor 2 (HER2) are transforming the treatment landscape for breast cancer. Sacituzumab govitecan (SG) and trastuzumab deruxtecan (T-DXd) have gained approval for an overlapping set of "HER2-low" metastatic breast cancers, including hormone receptor (HR)-positive HER2 non-amplified and "triple-negative" subtypes. Nevertheless, the optimal selection of patients and treatment sequencing for these ADC therapies remains a clinical challenge. Clinical trial objective response rates to SG are approximately 30%, compared to 30-90% for T-DXd depending on HER2 expression levels. While both drugs are thought to be targeted therapies, the value of measuring the target and the best methods to do so are still not established. We believe that quantitative measurement of TROP2 and HER2 antigen expression levels could establish thresholds for responders, enabling more effective patient selection for ADC therapies. Here, we present a TROP2, high-sensitivity HER2, and cytokeratin (CK) quantitative immunofluorescence (QIF) multiplex assay. Using a ten-cell line standard array and proteomic mass spectrometry, we can convert tumor compartment QIF intensity to protein concentration in fmol/mm2 for tissue specimens. Anti-HER2, anti-TROP2 antibodies, and fluorescence detection systems were titrated and combined to maximize signal-to-noise ratio on our cell line standard array and breast cancer tissue microarrays (TMA). The multiplex assay was designed for automated slide stainers (Leica BOND Rx) and fluorescence slide scanning (Rarecyte CyteFinder II HT). We perform our analyses in QuPath using an image processing plugin developed for automated QIF/IHC analysis (Qymia). Reproducible TROP2 and HER2 QIF scoring (R² > 0.95) was achieved across multiple staining batches using serial sections of breast cancer TMAs and cell standard arrays. This assay has a TROP2 linear range between 0.63 - 9.17 fmol/mm2 (about 1 million TROP2 receptors/cell) and HER2 linear range between 0.09 - 0.565 fmol/mm2 (about 60,000 HER2 receptors/cell). We then applied this multiplex assay to two serial retrospective primary breast cancer cohorts from Yale University to quantitatively measure TROP2 and HER2 expression (338 clinical cases). We find a weak negative correlation between TROP2 and HER2 expression in our breast cancer cohorts (Pearson r = -0.14, p = 0.0097, n = 338). TROP2 expression levels were above the limit of detection (LOD) in 90.2% of cases, with 4.1% exceeding the limit of linearity (LOL), and a mean TROP2 expression of 4.05 fmol/mm2. For HER2, 67.2% of cases were above the LOD, with 7.1% exceeding the LOL, and a mean HER2 expression of 0.186 fmol/mm2. Both TROP2 and HER2 were below the LOD in 3.0% of cases, which we define as “negative”. We found 29.9% expressed TROP2 and were HER2-negative, and 6.8% expressed HER2 and were TROP2-negative. Our future studies will aim to quantitatively define expression thresholds for T-DXd and SG response with the goal to produce a clinical grade assay for ADC patient selection and determine the value of the assay to help select which ADC to give first. HER2 and TROP2 protein expression summary in Yale breast cancer cohort Table 1: Summary of HER2 and TROP2 protein expression levels in serial retrospective primary breast cancer cohort of 338 cases using our high-sensitivity HER2 and TROP2 multiplex immunofluorescent assay Citation Format: Charles Robbins, Mengni He, Revekka Khaimova, Katherine Bates, Nay Nwe Nyein Chan, Daniel Liebler, Regan Fulton, David Rimm. Quantitative Multiplex Immunofluorescence Assay for TROP2 and HER2 Expression in Breast Cancer: Towards Guiding Patient Selection for Antibody Drug Conjugate Therapies [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 PO3-13-11.

Abstract 6891: Establishment and characterization of a panel of naïve and pretreated small cell lung cancer (SCLC) XPDX models

Abstract SCLC is an aggressive cancer of neuroendocrine origin, accounting for approximately 15% of all lung cancer cases. While the incidence of SCLC in the US has declined over past decades due to changes in smoking habits, this disease provides a poor prognosis and few effective treatment options for advanced disease. To better identify useful therapies for SCLC, we established and characterized a panel of 18 XPDX models representing primary and metastatic disease from either naïve or clinically treated patients and tested sensitivities towards chemotherapies and targeted agents. 18 models were established in immune-deficient mice including 8 from newly diagnosed patients (2 from lung primary), and 10 from recurrent disease (3 from lung primary). Models were IHC stained for Nectin-4, Trop2 protein and ERBB2 and profiled using WES and RNAseq. For in vivo studies, models were evaluated against several chemotherapies including cisplatin, etoposide, topotecan, and temozolomide, as well as ADC agents trastuzumab deruxtecan (T-DXd), enfortumab vedotin (EV), and sacituzumab govitecan (SG). Targeted therapies toward CDK4/6, KRASG12C, and PARP were evaluated in some models. Endpoints in all studies included tumor volume and time from treatment initiation with %T/C values and tumor regression reported at study completion; a %T/C of ≤ 20% versus control was considered sensitive. Tumor regression (%T/C<0%) versus Day 0 tumor volume was also reported. Less than 10% of models stained positive for Nectin-4, Trop-2 or ERBB2. Molecular characterization revealed RB1 frameshifts or deletions in most models, KRAS/NRAS point mutations in 3 models, and 2 gene fusions SEPTIN7P2-PSPH and TVP23C-CDRT4. In vivo studies reported differential responses to chemotherapies with the most sensitive models established from treatment-naïve patients. Temozolomide was active in several studies including tumor regressions in both naïve and pretreated models. ADCs also reported differential activity toward the tested panel. We have established and characterized a panel of SCLC XPDX models and benchmarked them against various cancer therapies. This panel can be utilized as a valuable tool in developing novel therapies for SCLC patients. Citation Format: Gabriela Huelgas Morales, Peter Forofontov, Johnnie Flores, Alyssa Simonson, Armando Diaz III, Jim Lund, Natalia Banos, Kyriakos Papadopoulos, Drew Rasco, Amita Patnaik, Ali Abedi, Napoleon Puente, Emiliano Calvo, Victor Moreno, Ronald Drengler, Lon Smith, Michael Wick. Establishment and characterization of a panel of naïve and pretreated small cell lung cancer (SCLC) XPDX models [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 6891.

Abstract 6899: Enfortumab vedotin (EV): Efficacy comparison with trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG) and its potential for combination benefit in bladder cancer XPDX models

Abstract EV is a Nectin-4 targeting antibody-drug conjugate (ADC) with an MMAE payload, recently approved for bladder cancer treatment. We established and characterized 18 bladder XPDX models representing primary and metastatic disease from naïve or clinically treated patients, some with actionable mutations. To better understand the potential additive benefit of EV in bladder cancer, we evaluated the ADC alone and in combination with agents targeting ERBB2, PIK3CA or FGFR3. In addition, we tested EV alone in ST5420B, a model established from a patient who progressed on EV after five cycles, as well as ST975B, a model which harbors a novel NECTIN4 fusion. 18 bladder XPDX models were established in immune-deficient mice, including 5 from newly diagnosed patients (2 from primary site), and 13 from recurrent disease (2 from primary site). Nectin-4, Trop2 protein and ERBB2 receptor expression was tested, and models profiled using WES and RNAseq. For in vivo studies, all models were evaluated against cisplatin, T-DXd, SG, and EV. Models with actionable mutations were tested with alpelisib, erdafitinib, and neratinib alone and in combination with EV. Endpoints in all studies included tumor volume and time from treatment initiation with %T/C values and tumor regression reported at study completion; a %T/C of ≤ 20% versus control was considered sensitive. Tumor regression (%T/C<0%) versus Day 0 tumor volume was also reported. Most models stained positive for Nectin-4 and Trop-2. FGFR3 variants were found in five models and ERBB2 mutations in two while several models reported PIK3CA variants; deletions in RB1 and CDKN2A were common. In vivo studies reported differential responses to cisplatin with the most sensitive models established from treatment-naïve patients. EV and SG tested alone reported activity in several models; EV added benefit in some combination treatments. We have characterized a panel of bladder XPDX models and benchmarked them against T-DXd, EV and SG alone and EV in combination with targeted therapies. This data is a valuable tool in further developing EV and identifying novel therapies for bladder cancer. Citation Format: Johnnie Flores, Heaven Sessions, Alyssa Simonson, Natalia Banos, Tahmineh Rouzbahani, Armando Diaz III, Jim Lund, Emiliano Calvo, Victor Moreno, Kyriakos Papadopoulos, Drew Rasco, Amita Patnaik, Scott Ulmer, Luis Rodriguez, Michael Wick. Enfortumab vedotin (EV): Efficacy comparison with trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG) and its potential for combination benefit in bladder cancer XPDX models [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 6899.

Abstract 936: Targeted proteomics and next-generation sequencing (NGS) for biomarker discovery in metastatic colorectal cancer (mCRC)

Abstract Background: Multi-omics analysis is widely used in cancer diagnosis, prognosis and prediction of treatment response. Here we introduce the use of targeted proteomics coupled with NGS as tools to assess oncogenic alterations along with quantitative protein expression in patients with mCRC. Our proteomics panel included proteins that are antibody drug conjugates (ADCs) targets (ERBB 1-4, TROP2, CEACAM5 etc.) as well as proteins involved in sensitivity to ADC payload (SLFN11, drug efflux pump, TOP1 etc.). Methods: The HORIZON III trial (NCT00384176) evaluated FOLFOX + bevacizumab or cediranib as first-line treatment in patients with mCRC (Schmoll J Clin Oncol 2012). In the current analysis, a subset of samples from the HORIZON III trial were assessed for molecular alterations using NGS and proteomics. Pre-existing HER2 IHC scores were used as previously referenced (Cecchi J Clin Oncol 2023). Samples were processed (n=135) with an automated extraction and library preparation method, then sequenced with both a Whole Exome and targeted-custom gene panel. NGS analysis had a success rate of 116/135 samples (87.3%). Absolute quantitation of protein targets was performed using parallel reaction monitoring (PRM) mass spectrometry after collecting tumor epithelial cells by laser microdissection and punch biopsies (n=60) followed by trypsin digestion. Results: The NGS analysis showed that patients had mutated RAS (50%), BRAF (10%), PIK3CA (16%), and TMB-H (18%) and MSI-H (5%) status. A distinguished pattern of mutual exclusivity among KRAS, NRAS, and BRAF mutations is evident. The HER2-positive patients were wildtype RAS, BRAF, and PIK3CA, MSS and TMB-L. Samples that were IHC HER2-positive matched those with NGS ERBB2 amplification. Using PRM, nearly all the evaluable samples had detectable HER2. HER2 IHC 3+ sample showed the highest protein expression at 30,000 amol/ug (equivalent to 1M receptors/cell). Within the HER2-negative patients, HER2 protein expression showed broad dynamic range. CEACAM5 and HER2 are the only ADC targets that reached the level of 1M receptors/cell. Highest TROP2 protein expression is 5 times lower than the highest HER2 value. Conclusions: Our preliminary findings for this cohort indicate the benefit of the use of multi-modal methodologies to inform better strategies for patient stratification and precision medicine, though further assessment of proteogenomic characteristics is needed. This data may inform future clinical development and guide patient eligibility to clinical trials and possible treatment sequencing for ADCs. Citation Format: William J. Kelly, Barrett Nuttall, Marlon Rebelatto, Marcus Schick, Armin Meier, Steve Sweet, Beom-Jun Kim, David Chain, Yeoun Jin Kim, Zhongwu Lai, Ying Wang, Todd H. Creasy, Ramya Gurrapu, Sakshi Gulati, Alice Barkell, Brian Dougherty, Danielle Carroll, Fabiola Cecchi. Targeted proteomics and next-generation sequencing (NGS) for biomarker discovery in metastatic colorectal cancer (mCRC) [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 936.

Diagnostic and prognostic utility of TROP-2, SLP-2, and CXCL12 expression in papillary thyroid carcinoma.

Papillary thyroid carcinoma (PTC) is the most frequent thyroid malignancy. Histopathological examination is widely accepted as the gold standard test for the diagnosis of PTC. However, the histopathological examination sometimes can't differentiate PTC from other thyroid diseases. Differentiating PTC from other thyroid diseases is essential for a therapeutic approach and prognosis. The current study was performed to investigate the utility of TROP-2, SPL-2, and CXCL12 mRNA and protein expression in discriminating PTC from other thyroid diseases that mimic PTC. The current study was performed on 75 cases of surgically resected thyroid glands. The cases were distributed in two groups: the PTC group and the non-PTC group. The PTC group consisted of 35 cases (25 patients of the classic PTC variant and 10 patients of the PTC follicular variant). The non-PTC group consisted of 40 cases (10 cases were multinodular goiter, 5 cases were Graves' disease, 5 cases were Hashimoto thyroiditis, 15 patients were follicular adenoma (FA) and 5 cases were follicular carcinoma). TROP-2, SPL-2, and CXCL12 mRNA expression were estimated by qRT-PCR, and protein expression was estimated by immunohistochemistry. There were upregulated TROP-2, SPL-2, and CXCL12 mRNA and protein expressions in PTC compared to non-PTC (P< 0.001, for each). There was a statistically significant upregulation in the mRNA expression of the three genes among PTC cases with larger tumor sizes (P< 0.001, for each), those with tumor stages III and IV (P= 0.008, 0.002 and < 0.001 respectively), and those with LN metastasis (P< 0.001, for each). Moreover, there was a statistically significant upregulation in CXCL-12 gene expression among PTC cases with extra-thyroid extension (P< 0.001). mRNA expression of TROP-2, SPL-2, and CXCL12 among PTC cases increased in larger tumor size, tumor stages III and IV, and LN metastasis. Moreover, there was an increase in CXCL-12 gene expression among PTC cases with extra-thyroid extension. Thus, TROP-2, SPL-2, and CXCL12 expressions could be possible diagnostic and prognostic markers in PTC.

Trop-2: A promising new therapeutic target in penile squamous cell carcinoma.

12 Background: Penile squamous cell carcinoma (PSCC) is an infrequent yet progressively prevalent malignancy. Despite ongoing advancements in personalized and immunotherapeutic approaches, patients grappling with the diagnosis of locally advanced or metastasized PSCC still confront a limited therapeutic arsenal, leading to an unfavorable prognosis. Consequently, an imperative mandate arises to explore alternative therapeutic modalities, particularly antibody-drug-conjugates (ADCs), which have demonstrated significant clinical efficacy in the context of metastatic solid tumor pathologies. Our aim was to ascertain the potential utility of ADCs targeting Trop-2 in both localized PSCC (PRIM) and patient-matched distant metastases (MET). Methods: Immunohistochemical analysis of Trop-2 expression was conducted in PRIM ( N=40) and their corresponding METs ( N=9, including lymph node and lung metastases). We assessed overall survival (OS) by stratifying patients into subgroups based on Trop-2 expression: weak (H-score 15-99) versus moderate/strong (H-score 100-300). Additionally, we explored the relationship between Trop-2 and HPV-dependency. Furthermore, Trop-2 mRNA expression levels were quantified via qRT-PCR, and an enzyme-linked immunosorbent assay was employed to measure Trop-2 in serum samples derived from PRIM ( N=40) and a healthy control group ( N=10). Results: We found a statistically significant increase in Trop-2 mRNA expression levels in individuals afflicted with PSCC compared to healthy controls ( p&lt;0.0001). Moreover, a notable elevation in Trop-2 protein expression was observed in the serum specimens obtained from PSCC patients ( p&lt;0.01). The majority of patients exhibited moderate to strong Trop-2 expression, indicative of a robust median H-score of 280 (interquartile range: 210-300). Subgroup analysis revealed a correlation between Trop-2 expression and HPV status ( p&lt;0.01), demonstrating discernible associations with more favorable clinical outcomes, as evidenced by the log-rank (Mantel-Cox) test ( p&lt;0.05). Conclusions: Trop-2 protein expression in PSCC holds prognostic significance. Furthermore, the elevated Trop-2 levels in both PRIM and PSCC metastases suggest that the Trop-2-targeted ADC, Sacituzumab govitecan, may emerge as a promising novel therapeutic intervention for these patients.

DNA demethylation and tri-methylation of H3K4 at the TACSTD2 promoter are complementary players for TROP2 regulation in colorectal cancer cells

TROP2 is a powerful cancer driver in colorectal cancer cells. Divergent epigenetic regulation mechanisms for the corresponding TACSTD2 gene exist such as miRNAs or DNA methylation. However, the role of TACSTD2 promoter hypermethylation in colorectal cancer has not been investigated yet. In this study, TROP2 expression strongly correlated with promoter methylation in different colorectal tumor cell lines. Treatment with 5-Azacytidine, a DNMT1 inhibitor, led to demethylation of the TACSTD2 promoter accompanied by an increase in TROP2 protein expression. TROP2 expression correlated with promoter methylation in vivo in human colon tumor tissue, thereby verifying promoter methylation as an important factor in the regulation of TROP2 expression in colorectal cancer. When performing a ChIP-Seq analysis in HCT116 and HT29 cells, we found that TACSTD2 promoter demethylation was accompanied by tri-methylation of H3K4. In silico analysis of GSE156613 data set confirmed that a higher binding of histone mark H3K4me3 around the TACSTD2 promoter was found in TACSTD2 high expressing tumors of colon cancer patients compared to the corresponding adjacent tumor tissue. Moreover, the link between TROP2 and the H3K4me3 code was even evident in tumors showing high intratumoral heterogeneity for TROP2 staining. Our data provide novel evidence for promoter demethylation and simultaneous gains of the active histone mark H3K4me3 across CpG-rich sequences, both being complementary mechanisms in the transcriptional regulation of TACSTD2 in colon cancer. The functional consequences of TROP2 loss in colorectal cancer needs to be further investigated.

Trop-2 Is Highly Expressed in Early Luminal-Like Breast Cancer.

Trop-2, a transmembrane glycoprotein, has been identified in human epithelial cells as a contributor to tumor growth and unfavorable prognosis in breast cancer (BC). Our study aimed to assess the expression of Trop-2 protein via immunohistochemistry (IHC) and correlate it with clinicopathological features in early luminal-like BC. We conducted a cross-sectional study evaluating Trop-2 protein expression in tissue microarrays using IHC. The expression was evaluated by the H-score and the following categorization was used: H-Score 0 to <100 as low, H-Score 100 to 200 as intermediate, and H-Score >200 to 300 as high. The study included 84 patients with a median age of 57, of whom 70% had invasive ductal carcinomas, 75% were classified as T2, and 47.6% had no affected lymph nodes. Trop-2 expression was high in 56% of patients and intermediate in 38%. None of the patients had an H-Score of zero. No correlation was observed between Trop-2 expression and clinicopathological features, including age, histological subtype, grade, Ki67, tumor size, nodal status, lymphovascular invasion, tumor subtype, and pathological staging. We demonstrated that Trop-2 is highly expressed in early luminal-like BC and is not influenced by clinicopathological features.

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.

A non-mutated TROP2 fingerprint in cancer genetics.

The advent of high throughput DNA sequencing is providing massive amounts of tumor-associated mutation data. Implicit in these analyses is the assumption that, by acquiring a series of hallmark changes, normal cells evolve along a neoplastic path. However, the lack of correlation between cancer risk and global exposure to mutagenic factors provides arguments against this model. This suggested that additional, non-mutagenic factors are at work in cancer development. A candidate determinant is TROP2, that stands out for its expression in the majority of solid tumors in human, for its impact on the prognosis of most solid cancers and for its role as driver of cancer growth and metastatic diffusion, through overexpression as a wild-type form. The Trop-2 signaling network encompasses CREB1, Jun, NF-κB, Rb, STAT1 and STAT3, through induction of cyclin D1 and MAPK/ERK. Notably, Trop-2-driven pathways vastly overlap with those activated by most functionally relevant/most frequently mutated RAS and TP53, and are co-expressed in a large fraction of individual tumor cases, suggesting functional overlap. Mutated Ras was shown to synergize with the TROP2-CYCLIND1 mRNA chimera in transforming primary cells into tumorigenic ones. Genomic loss of TROP2 was found to promote carcinogenesis in squamous cell carcinomas through modulation of Src and mutated Ras pathways. DNA methylation and TP53 status were shown to cause genome instability and TROP gene amplification, together with Trop-2 protein overexpression. These findings suggest that mutagenic and the TROP2 non-mutagenic pathways deeply intertwine in driving transformed cell growth and malignant progression of solid cancers.

Abstract B016: Liquid biopsy biomarker analysis of a phase II trial of sacituzumab govitecan in castrate resistant metastatic prostate cancer

Abstract Background: Sacituzumab Govitecan (SG) is an antibody-drug conjugate targeting Trop-2 and has been approved for use in breast and bladder cancers. Trop-2 has been shown to be overexpressed in multiple solid tumors including prostate cancer. Here we report an interim analysis of longitudinal liquid biopsies collected in a phase II clinical trial of SG to identify biomarkers of response and resistance. Methods: We collected longitudinal blood samples from 20 patients for circulating tumor cell (CTC) and cell-free DNA (cfDNA) analysis as part of an open label Phase II trial of SG in patients with mCRPC (ClinicalTrials.gov Identifier: NCT03725761). Eligibility criteria for the trial included rising PSA and radiographic progression on abiraterone acetate or enzalutamide in the mCRPC setting. Liquid biopsies were collected at baseline, C1D8, and then every 3 cycles until disease progression. cfDNA was sequenced using a custom 822 gene targeted capture panel (IDT). CTCs were isolated with antibodies to either EpCAM or Trop-2 followed by parallel enumeration, EpCAM and Trop-2 protein phenotyping and RNA extraction for AR/NEPC marker transcriptional profiling. Results: Although no PSA50 responses were observed, the 6-month rPFS rate was 45% (64% in chemotherapy naïve patients). For this analysis, these patients will be termed responding patients. The number of Trop-2-postive CTCs at baseline was significantly higher in responding (24.3 ±13.4 per 7.5 mL blood) than non-responding (10.0±3.8) patients. During treatment the number of Trop-2 positive CTCs in responders significantly decreased by C3D1 to 10.0 ±3.8. Interestingly, while the number of Trop-2 positive CTCs continued to decline to 2.8±1.99 cells/7.5 mL, EpCAM-positive CTCs increased from 12.5±10.52 cells/7.5 mL to 23.2±19.49 at end of trial. Gene expression analysis demonstrated high expression of genes specific to adenocarcinoma including AR-splice variants, TMPRSS2, KLK2 and KLK3 in the majority of patients, with conversion to AR-variant negative CTCs identified in responders. Preliminary cfDNA analysis identified one patient with a mutation acquired in the gene encoding topoisomerase 1 (TOP1) upon progression on SG, with additional analysis ongoing. Conclusions: Patients who responded to SG had a more Trop-2 positive CTCs with adenocarcinoma characteristics with expression of AR pathway genes. Longitudinal analysis of liquid biopsy biomarkers identified multiple mechanisms of acquired SG resistance. Decline in Trop2-CTC population with parallel expansion of EpCAM-CTC population in multiple patients suggests loss of Trop2 surface protein expression as resistance mechanism, while identification of a cfDNA TOP1 mutation in one patient at time of progression is consistent with acquired resistance to the topoisomerase inhibitor payload as has been reported in metastatic triple negative breast cancer. Citation Format: Jamie M. Sperger, Amy K. Taylor, Yue Shi, Charlotte N. Stahlfeld, Kyle Helzer, Matthew Bootsma, Katherine R. Kaufmann, Marina N. Sharifi, Christos E. Kyriakopoulos, Susan Slovin, Scott Tagawa, Scott Dehm, Shuang G. Zhao, Joshua M. Lang. Liquid biopsy biomarker analysis of a phase II trial of sacituzumab govitecan in castrate resistant metastatic prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B016.

Efficacy of sacituzumab govitecan (SG) in locally advanced (LA) or metastatic urothelial cancer (mUC) by trophoblast cell surface antigen 2 (Trop-2) expression.

4579 Background: Patients (pts) with mUC have an estimated 5-year overall survival (OS) rate of 14%. Trop-2 is a transmembrane glycoprotein with elevated expression in many cancers, including UC. SG is a Trop-2–directed antibody-drug conjugate with accelerated FDA approval for pts with LA unresectable or mUC who previously received platinum (PT) and a checkpoint inhibitor (CPI). SG has demonstrated activity in 3 phase 2 TROPHY-U-01 mUC cohorts: Cohort 1 (C1), 28% objective response rate (ORR); Cohort 2 (C2), 32% ORR; and Cohort 3 (C3), 41% ORR. Here, we assess efficacy outcomes in C1-3 by Trop-2 archival tumor expression. Methods: Pts (≥18 years) with previously treated (PT [C3], CPI [C2], or both [C1]) LA or mUC received SG (10 mg/kg IV) on D1 and D8 of 21-D cycles; C3 pts also received pembrolizumab (200 mg) on D1 of 21-D cycles. The primary endpoint was ORR by independent review. Archival tumor samples collected at enrollment were assessed for Trop-2 protein expression using SP295 anti–Trop-2 antibody by IHC with assessment by histological scores (H-scores; scale, 0-300) and % of membrane-positive tumor cells (Roche Tissue Services). Trop-2 association with clinical endpoints was evaluated using unstratified Cox proportional hazards models for survival data and logistic regression for ORR. Results: At data cutoff, 192 pts were enrolled in C1-3; 144 pts (75%) had samples evaluable for Trop-2 prevalence and 139 pts (72%) were evaluable for efficacy analysis by Trop-2 expression (5 pts not assigned to any cohort were excluded). Baseline characteristics for pts with evaluable samples were consistent with the overall population. Median (IQR) Trop-2 H-score and % of membrane-positive tumor cells for evaluable pt samples were 215 (180-247) and 92% (75-98), respectively; these readouts were highly correlated (ρ=0.82, P&lt;0.001). ORRs for C1 samples with below (n=42) and above (n=45) median Trop-2 H-scores were 24% and 29% ( P=0.59), respectively; median progression-free survival (PFS) was 3.4 and 6.7 months (HR=0.765, P=0.262), respectively; and median OS was 9.9 and 10.9 months (HR=0.978, P=0.927), respectively. Median PFS for C1 samples with below and above median Trop-2 membrane positivity were 3.9 and 6.2 months (HR=0.835, P=0.443), respectively. Analyses of efficacy endpoints for C2 and C3 pt samples by Trop-2 expression were consistent with C1 results. Conclusions: In this analysis of archival tumor samples from pts with pretreated LA or mUC, Trop-2 protein was highly expressed across cohorts, supporting prior Trop-2 expression analyses in UC. Similar outcomes were observed between C1 pts with samples that were below and above median Trop-2 H-score with most pronounced numerical differences observed for PFS. These results suggest that SG activity may be independent of Trop-2 expression in UC, but additional studies are needed to confirm these results. Clinical trial information: NCT03547973 .

Abstract P3-08-05: Correlation of Trop2 expression with in vivo sensitivity to sacituzumab govitecan in a panel of breast XPDX models

Abstract Background: Sacituzumab govitecan (SG) is an antibody-drug conjugate targeting Trop2 with an SN-38 payload recently approved for pretreated patients with locally advanced or metastatic triple-negative breast cancer (TNBC). The XenoSTART Patient-Derived Xenograft (XPDX) breast cancer platform includes over 180 models spanning all subtypes characterized with immunohistochemistry (IHC) including ER, PR, and HER2 protein levels, genomic and transcriptomic sequencing, and in vivo drug sensitivity. To better understand potential benefit of SG in breast cancers other than TNBC and further annotate our platform, Trop2 protein levels were determined in all breast models by IHC. We evaluated tumor growth inhibition by SG in 125 of our XPDX breast models and compared protein expression with agent activity. Methods: 180 breast XPDX models were evaluated for Trop2 expression (AF650, R&amp;D Systems) and 125 were evaluated in vivo against SG; responses were grouped by ER and Trop2 status (+/-). Models were grown subcutaneously in female athymic nude mice and ER+ models supplemented with estradiol. Models were also characterized for PR, HER2, and AR protein expression by IHC and profiled using WES and RNAseq. For in vivo studies, SG was administered by intravenous injection biweekly for two cycles at 1 mg, flat; endpoints included tumor volume and time from treatment initiation with %T/C values and tumor regression reported at study completion; a T/C of ≤ 20% versus control was considered sensitive. Tumor regression (%T/C&amp;lt; 0%) versus Day 0 tumor volume was also reported. Results: 180 breast models were examined by IHC with 75/180 (42%) classified as ER+ and 105/180 (58%) ER-. In ER+ models 38/75 (51%) were Trop2+ and 37/75 (49%) Trop2-, and in ER- models 41/105 (39%) were Trop2+ and 64/105 (61%) Trop2-. In vivo, 20% of ER+/Trop2+ models reported sensitivity to SG, most notably models from patients with acquired resistance to CDK4/6 inhibitors, including STM001 and ST4316B. Interestingly, &amp;gt;70% of ER+/HER2+/Trop2+ models were insensitive to SG, including ST225 and ST340. Of 41 ER-/Trop2+ models, approximately 40% reported some response to SG with 50% of these sensitive to therapy, including ST5954 established from a patient who began treatment with SG following sample collection and is currently in remission. &amp;gt;75% of Trop2- models were insensitive to SG regardless of ER status. Conclusion: We screened 180 models in our XPDX breast cancer platform for Trop2 expression and compared expression with in vivo SG efficacy in 125 models. Analysis is underway to correlate receptor and molecular profiles with SG sensitivity in breast models and we are expanding expression and in vivo testing to additional indications. Citation Format: Alyssa Simonson, Johnnie Flores, Ebony Anderson, Crystal Moreno, George Plasko, Kyriakos P. Papadopoulos, Amita Patnaik, Drew Rasco, Gladys Rodriguez, Amy Lang, Muralidhar Beeram, Luis Rodriguez, Ronald Drengler, Steven Abbate, Hanni Salih, Lon Smith, Maryam Elmi, Brittany DeBerry, Arthur Rosenthal, Tatiana Hernandez, Nehal Lakhani, Manish Sharma, Michael Wick. Correlation of Trop2 expression with in vivo sensitivity to sacituzumab govitecan in a panel of breast XPDX models [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 P3-08-05.

Abstract HER2-17: HER2-17 Novel Quantitative HER2 Assay for Determining Dynamic HER2 Expression in the HER2 IHC 0 “Ultra-Low” Setting: Implications for Precision Therapy in HER2- Breast Cancer

Abstract Background: The HER2 antibody drug conjugate (ADC) fam-trastuzumab deruxtecan-nxki (T-DXd) significantly improves outcomes over standard chemotherapy in pts with HER2-LOW (IHC 1+ and IHC 2+ FISH-) metastatic breast cancer (MBC). Data from the DAISY (NCT04132960) trial in pts with HER2 IHC 0 or “ultra low” MBC revealed median progression-free survival (PFS) of 4.2 mos vs 6.7 mos in HER2-LOW and 11.1 mos in HER2 3+ pts (Diéras V, et al. Cancer Res. 2022;82(4_Suppl):PD8-02). There is an urgent need to develop methods to accurately discern HER2 LOW expression versus HER2 IHC 0/ultra-low expression so appropriate pts may receive T-DXd. We have developed a quantitative HER2 assay using reverse phase protein array (RPPA) technology with laser capture microdissection (LCM) enrichment of tumor epithelium that measures HER2 expression over a 65-fold dynamic range in HER2 IHC 0 to 3+ breast cancers. In I-SPY 1 and 2 trials we found that RPPA-assessed quantitative HER2 and activated/phosphorylated HER2 expression predicted for pathologic complete response in pts with HER2 IHC 0, HER2-LOW and HER2 3+ disease with various HER2 and other targeted agents. We then developed and validated the first CLIA/CAP-accredited quantitative HER2 protein expression and activation assay, and now explore quantitative HER2 expression in HER2 IHC 0/ultra low disease. Given the recent approval of sacituzumab govitecan-hziy in TNBC and the results of the TROPiCS-02 (NCT03901339), we also evaluated quantitative RPPA-based TROP-2 expression levels in HER2 IHC 0 breast cancer. Methods: LCM-enriched tumor epithelium was obtained from freshly cut FFPE core needle and resected breast cancer samples from 175 pts with pathology-determined HER2 IHC 0 status (N=68 ER+ and N=107 ER-). Quantitative HER2 output is generated as a relative intensity unit (RU) that is interpolated to an internal calibrator curve and a population referent comprised of known HER2+ (IHC 3+ and 2+/FISH+), HER2-LOW and HER2 IHC 0/ultra-low tumors to generate population-based cut-points as a referent. RPPA-based quantitative HER2 expression are reported as one of four levels of expression across the HER2 dynamic range observed: “non/extremely low”, “modest“, “moderate”, and “high”. Quantitative TROP2 protein expression levels were also measured for each case by the RPPA assay on the same lysate using the same adjectival determinants of relative expression as HER2. Results: For the HER2 IHC 0 ER+ cohort, we observed HER2 protein expression over a 25-fold dynamic range and that 57% (N=39) had HER2 non/extremely low, 37% (N=25) modest, and 4 (6%) moderate/high HER2 expression by RPPA. For the HER2 IHC 0 ER- cohort, we observed HER2 protein expression over a 15-fold dynamic range and that 71% (N=76) had non/extremely low, and 31% (N=29%) modest HER2 expression. We observed TROP-2 protein expression over a 35-fold dynamic range across all tumors measured, and it was found to be at least modestly expressed in 95% (37/39) ER+ and 95% (72/76) ER- of the IHC 0/ultra-low tumors that were also found to be HER2 non/extremely low by RPPA. Conclusions: LCM-RPPA quantitative assessment of HER2 expression showed that nearly 40% of ER+ IHC 0 and 30% of ER- IHC 0 “ultra-low” breast cancers actually had modest to moderate HER2 expression. Interestingly, this frequency approximates the response rate of 30% seen with T-DXd in HER2 IHC 0 pts in the DAISY trial. Quantitatively measured TROP2 is at least modestly expressed in the vast majority of RPPA-assessed HER2 IHC 0 cancers regardless of ER status, making a TROP2-directed ADC an attractive therapeutic option for these pts. If validated in larger studies, LCM-RPPA-based HER2 expression could provide a better understanding of the potential for therapeutic efficacy with T-DXd in patients with HER2 IHC “ultra-low” disease, and may better define true ultra-low HER2 expression in HER2 IHC 0 tumor biopsies at baseline and refine the lower limit of the HER2-LOW designation. Citation Format: Emanuel F. Petricoin, Brian A. Corgiat, Joyce O’Shaughnessy, Patricia LoRusso, Kris Weinberg, Justin Davis, Chelsea Gawryletz. HER2-17 Novel Quantitative HER2 Assay for Determining Dynamic HER2 Expression in the HER2 IHC 0 “Ultra-Low” Setting: Implications for Precision Therapy in HER2- Breast Cancer [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 HER2-17.

Correlation of TROP-2 expression with clinical–pathological characteristics and outcome in triple-negative breast cancer

Limited data exist regarding the associations between TROP-2 protein expression, clinical–pathological characteristics, and outcome in triple-negative breast cancer (TNBC). TROP-2 expression was determined for patients diagnosed with TNBC between 2000 and 2017 by immunohistochemistry (IHC) (ab227689, Abcam) on whole slide tumor sections, and assessed as continuous and categorical variables (H-score high, 201–300, medium 100–200 and low < 100). We investigated the prognostic value of TROP-2 expression for relapse and survival, associations between TROP-2 expression and baseline patient and tumor characteristics, stromal tumor-infiltrating lymphocytes (sTILs), androgen receptor (AR), standardized mitotic index (SMI) and pathological complete response (pCR, in patients with neoadjuvant chemotherapy) were assessed. We included 685 patients with a median age at diagnosis of 54 years (range 22–90 years). After median follow-up of 9.6 years, 17.5% of patients experienced distant relapse. TROP-2 expression was high, medium and low in 97 (16.5%), 149 (25.3%) and 343 (58.2%) of patients, respectively. The presence of LVI, associated DCIS, nodal involvement, apocrine histology and AR expression were correlated with higher TROP-2 levels. There were no associations between TROP-2 expression and sTILs, time-to-event outcomes, or pCR rate after neoadjuvant chemotherapy. TROP-2 expression is not associated with sTILs level and has no prognostic value in our cohort of stage 1–3 TNBC. However, an association with histotype and AR expression was found, suggesting a histotype specific TROP-2 expression pattern with highest expression in apocrine subtype, warranting further research.

Abstract 5127: Significance of Trop-2 in HER2-positive breast cancer

Abstract Purpose: The glycoprotein Trop-2 is frequently overexpressed in human malignancies and linked to worse outcome. A Trop2-targeting antibody-drug conjugate, sacituzumab govitecan, has been approved by the FDA for patients with unresectable locally advanced or metastatic triple-negative breast cancer. Trop-2 enhances Akt phosphorylation in numerous cancer cell lines, while the opposite findings are also reported suggesting the cell context-dependent effect of Trop-2. Blockade of PI3K/Akt pathway mediates anti-tumor mechanism of anti-HER2 agents. In this study, we aim to investigate the role of Trop-2 in HER2-positive breast cancer. Experimental design: The archival samples comprising different breast cancer subtypes were analyzed using immunohistochemical staining. The public databases, including, Metabric, KM plotter, ROC plotter, were used to verify the prognostic role and clinical significance of Trop-2 in HER2-positive breast cancer. In vitro tumor models, the transwell migration, invasion and sphere assays, were applied for evaluation of cancer progression. The apoptotic cells were determined by flow cytometry using Annexin V/propidium iodide double staining. Results: We analyzed a cohort of 986 breast cancer patients and found that HER2-positive breast cancer harbored higher Trop-2 protein expression than other breast cancer subtypes. Higher levels of Trop-2 and phospho-Akt in HER2-positive breast cancer tissues compared with normal tissues. Trop-2 expression was correlated with tumor stage and phospho-Akt level. HER2-positive breast cancer patients with high level of Trop-2 protein were linked to worse recurrence-free survival. Consistently, data from the public databases exhibited patients with higher level of Trop-2 transcript had shorter recurrence-free survival and overall survival of HER2-positive breast cancer. Overexpression of Trop-2 increased cell migration, invasion and sphere number in SK-BR-3 and BT-474 cells. In contrast, knockdown of Trop-2 suppressed cell motility and sphere formation. Trop-2-expressing cells had better cell viability compared to control cells in the presence of lapatinib or neratinib treatment. Lapatinib- and neratinib-induced cell apoptosis was rescued by Trop-2 overexpression. Notably, patients responded to anti-HER2 therapy had lower Trop-2 transcript expression than non-responders. Conclusion: These results suggested that the oncogenic role of Trop-2 in HER2-positive breast cancer and Trop-2 expression might confer resistance to anti-HER2 therapy. Citation Format: Chun-Yu Liu, Ji-Lin Chen, Pei-Yi Chu, Chun-Teng Huang, Wan-Lun Wang, Chi-Cheng Huang, Po-Han Lin, Ling-Ming Tseng. Significance of Trop-2 in HER2-positive breast cancer [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 5127.

Abstract 1646: Humanized TROP2 mice provide a preclinical tool for the evaluation of therapeutic drugs targeting TROP2

Abstract Human TROP2, also known as tumor-associated calcium signal transducer 2 (TACSTD2), is a type I cell surface glycoprotein that mediates intracellular calcium signals. It plays a crucial role in cell proliferation, survival, self-renewal, and cell adhesion. Several ligands are found to interact with TROP2, including claudin-1, claudin-7, cyclin D1, and IGF-1. TROP2 is expressed on the surface of many stem and progenitor cells as well as other tissues. Importantly, TROP2 is highly expressed in a variety of solid tumors, making it a new target for the development of antibody-conjugated drugs. To evaluate the efficacy of anti-TROP2 antibodies, we generated a humanized B-hTROP2 mouse at Biocytogen. In this mouse model, the murine TROP2 gene was replaced by the full length human TROP2 gene. Western blot analysis showed that human TROP2 protein expression was detected in skin and kidney of homozygous B-hTROP2 mice. These results suggest that B-hTROP2 mice is an ideal tool for in vivo efficacy evaluation of therapeutic drugs targeting human TROP2. Citation Format: Dexuan Huang, Zhiyuan Shen, Limei Ma, Chong Li, Tianquan Jin. Humanized TROP2 mice provide a preclinical tool for the evaluation of therapeutic drugs targeting TROP2 [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 1646.