Expert consensus on the clinical application of TROP2-targeted antibody-drug conjugates in non-small cell lung cancer (2026 edition)

Introduction: Non-small cell lung cancer (NSCLC) is a major cause of cancer-related deaths globally with high unmet need. A variety of novel therapeutic strategies are being explored to improve patient outcomes including the use of antibody drug conjugates (ADCs) to deliver highly potent, cytotoxic payloads to tumors. Trophoblast cell-surface antigen 2 (TROP2), also known as tumor-associated calcium signal transducer 2 (TACSTD2), has emerged as an attractive target for ADCs. Sacituzumab govitecan-hziy is a novel ADC composed of a TROP2 antibody coupled to SN-38 and is being evaluated in NSCLC. High TROP2 mRNA expression is observed in many tumor types, however, TROP2 protein expression in NSCLC is not well-established. Here we characterized TROP2 expression across three independent datasets to explore the TROP2 relationship to baseline characteristics, molecular features of interest, and its prognostic value in NSCLC. Methods: We analyzed three independent datasets: (1) The Cancer Genome Atlas (TCGA) NSCLC adenocarcinoma (LUAD, N=660) and squamous cell carcinoma (LUSC, N=484) mRNA expression data, (2) a NSCLC adenocarcinoma FFPE tumor sample set (“Translational data set”; N=107), (3) an independent clinical NSCLC adenocarcinoma (N=103) and squamous cell carcinoma (N=37) data set. TROP2 IHC was performed on tumor sample sets (2) and (3) using the SP295 antibody (Robust Prototype Assay, Ventana) with H-Score and assessment of the percentage of membrane-positive tumor cells as readouts. Wilcoxon rank-sum and Kruskal-Wallis tests (continuous variables), Kaplan-Meier method (survival probability curves) and log-rank test (time to event outcome) were used (GraphPad Prism 8.1.2 and R version 4.0.5). Results: TROP2 mRNA was highly expressed in NSCLC and expression was similar in adenocarcinoma and squamous cell carcinoma in the TCGA data set. TROP2 expression did not vary with patient’s age, gender, race or tumor stage. Furthermore, TROP2 expression was not associated with TP53, KRAS or driver mutation status (including EGFR, ALK, ROS, RET, MET). TROP2 expression in the Translational sample set was consistent with the findings from the TCGA data analysis: TROP2 mRNA and protein expression were high and independent of patient baseline demographics, tumor stage and TP53 and KRAS mutation status. Finally, in an independent clinical NSCLC dataset, TROP2 protein was highly expressed and there was no relationship between TROP2 and baseline demographics including gender and age. TROP2 membrane H-scores and percentage of membrane-positive tumor cells also highly correlated in the two independent datasets. Conclusions: Three large independent datasets confirmed high expression of TROP2 in NSCLC both, as mRNA and protein. TROP2 expression in tumors did not differ between histological subtypes, baseline characteristics or clinically relevant driver alterations. Based on the TCGA data set, TROP2 expression was not prognostic for survival. Citation Format: Peiwen Kuo, Emon Elboudwarej, Lauri Diehl, Jilpa Patel, Sabeen Mekan, Juliane M. Jürgensmeier. TROP2 expression in non-small cell lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4396.

BACKGROUND/AIM: Trophoblast cell surface antigen-2 (TROP2), a transmembrane glycoprotein often overexpressed in a variety of cancers, has been proposed as a potential cancer driver in colorectal cancer (CRC) cells. As a result, several antibody-drug conjugates (ADC) have been developed targeting TROP2, such as Sacituzumab Govitecan (SG) and Datopotamab Deruxtecan (Dato-Dxd). One of the major challenges in the development of ADC is the emergence of resistance via different mechanism of actions. This study aims to characterize the potential resistant mechanisms of TROP2 ADCs, including a novel TROP2 ADC OBI-992 in CRC cells. METHODS: DLD1 CRC cells resistant to OBI-992, SG, and Dato-Dxd analogs were established with sequential increase of respective ADC concentrations. Cytotoxicity of three ADCs and their payloads, including exatecan, SN-38, and Dxd, was evaluated to assess the fold of resistance. Cell surface and total TROP2 protein were measured by flow cytometry and western blotting. DNA mutation and gene expression profiling were conducted by whole exome sequencing (WES) and RNA sequencing (RNA-seq). RESULTS: TROP2 reduction and multidrug resistance proteins (MRPs) enhancement were not detected in OBI-992-induced resistant cells. Notable different DNA mutations in ATRX, BRCA2, and PALB2 of OBI-992 resistant cells were detected compared to those found with Dato-Dxd and SG-selected resistant cells. A TOP1 inhibitor-resistant mutation, TOP1 R364H, was identified as 100% variant allele frequency (VAF) in Dato-Dxd and SG resistant cells, whereas lower percentage of VAF was observed in OBI-992 resistant cell lines (29 % and 48.6 % in 0.5 uM and 2uM of OBI-992, respectively). OBI-992 resistant cells showed a clear divergence in differential expression gene (DEG) profiles, whereas Dato-Dxd and SG resistant cells were similar. c-MET and REG4 levels were greatly increased in cells with Dato-Dxd and SG resistance but not with OBI-992. Extracellular matrix (ECM) receptor interaction pathway was enriched in OBI-992 resistant cells. CONCLUSION: OBI-992, a novel TROP2 targeting ADC, emerges as a potential promising therapeutic option for patients who are resistant to other TROP2 targeting ADCs such as SG and Dato-Dxd. OBI-992 exhibits distinct resistance profiles compared to other TROP2 targeting ADCs. Understanding of potential mechanisms of resistance can provide potential combination options for TROP2-targeting ADCs to combat the drug resistance. Citation Format: Lifen Shen, Tzer-Min Kuo, Yu-Hsuan Tsao, Ya-Chi Chen, Ming-Tain Lai. OBI-992, a novel TROP2 antibody-drug conjugate, exhibits distinct resistance profiles compared to other TROP2 targeting ADCs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1702.

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.

TROP-2 directed antibody-drug conjugates (ADCs): The revolution of smart drug delivery in advanced non-small cell lung cancer (NSCLC)

Trophoblast cell surface antigen 2 (TROP2) is the target of sacituzumab govitecan (SG), an antibody-drug conjugate that was recently approved for previously treated triple negative breast cancer and urothelial carcinomas. To comprehensively determine TROP2 expression in normal and neoplastic tissues, a tissue microarray containing 18,563 samples from 150 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. TROP2 positivity was found in most normal epithelial cell types and in 109 of 150 tumor categories, including 92 of 95 epithelial tumor categories. Particularly high rates of TROP2 positivity and highest expression levels were seen in squamous cell carcinomas of various origins and various categories of urothelial, breast, prostate, pancreatic, and ovarian cancers (>95% positive). High TROP2 expression was linked to advanced stage (p=0.0069) and nodal metastasis (p<0.0001) in colorectal cancer as well as to nodal metastasis in gastric adenocarcinoma (p=0.0246) and papillary thyroid cancer (p=0.0013). Low TROP2 expression was linked to advanced stage in urothelial carcinoma (p<0.0001), high pT (p=0.0024) and high grade (p<0.0001) in breast cancer, as well as with high grade (p=0.0005) and pT stage (p=0.0009) in papillary renal cell carcinomas. Associations between TROP2 expression and clinicopathological features were not found in clear cell renal cell carcinomas, high grade serous ovarian carcinomas, pancreatic adenocarcinomas and in endometroid endometrium carcinomas. In summary, TROP2 is abundantly expressed in a broad range of epithelial neoplasms. Both TROP2 upregulation and downregulation can be associated with cancer progression in a tumor type dependent manner. As anti-TROP2 cancer drugs have demonstrated efficiency and induce tolerable side effects they may be applicable to a broad range of tumor entities in the future. Citation Format: David Dum, Claudia Hube-Magg, Ronald Simon, Elena Bady, Tim Mandelkow, Niclas C. Blessin, Maximilian Lennartz, Guido Sauter, Sarah Minner, Andreas M. Luebke. Trophoblast cell surface antigen 2 (TROP2) expression in human tumors: A tissue microarray study on 18,563 tumors [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 1861.

Simple SummaryThe trophoblast cell surface antigen 2 (TROP2) is a protein produced by many carcinomas. Sacituzumab govitecan (SG) is a drug consisting of an antibody that binds to TROP2 on the tumor cell when TROP2 is present and is taken up into the cell interior after binding. The antibody is coupled with a cytotoxic substance (SN38) that is released inside the cell after uptake. As a result, a lethal dose of SN38 acts specifically in the tumor cell while having a small systemic effect, reducing the extent of side effects. We can show here that TROP2 is formed in nearly 90% of esophageal adenocarcinomas (EAC) and that sacituzumab govitecan is also effective in EAC. We can show that efficacy is dependent on the presence of TROP2 on the cancer cell - complete absence of TROP2 is associated with poor response rate to SG. We therefore advocate determining TROP2 at the protein level prior to therapy. Suitable immunohistochemical antibodies for routine testing exist.Introduction: The Trophoblast cell surface antigen 2 (TROP2) is expressed in many carcinomas and may represent a target for treatment. Sacituzumab govitecan (SG) is a TROP2–directed antibody-drug conjugate (ADC). Nearly nothing is known about the biological effectiveness of SG in esophageal adenocarcinoma (EAC). Material and Methods: We determined the TROP2 expression in nearly 600 human EAC. In addition, we used the EAC cell lines (ESO-26, OACM5.1C, and FLO-1) and a xenograft mouse model to investigate this relationship. Results: Of 598 human EACs analyzed, 88% showed varying degrees of TROP2 positivity. High TROP2 positive ESO-26 and low TROP2 positive OACM5.1C showed high sensitivity to SG in contrast to negative FLO-1. In vivo, the ESO-26 tumor shows a significantly better response to SG than the TROP2-negative FLO-1 tumor. ESO-26 vital tumor cells show similar TROP2 expression on all carcinoma cells as before therapy initiation, FLO-1 is persistently negative. Discussion: Our data suggest that sacituzumab govitecan is a new therapy option in esophageal adenocarcinoma and the TROP2 expression in irinotecan-naïve EAC correlates with the extent of treatment response by sacituzumab govitecan. TROP2 is emerging as a predictive biomarker in completely TROP2-negative tumors. This should be considered in future clinical trials.

Introduction: Trophoblast cell-surface antigen 2 (Trop-2) has become an attractive antibody drug conjugate (ADC) target as it is expressed in multiple solid tumors. Sacituzumab govitecan (SG), an ADC composed of a Trop-2 antibody coupled to SN-38 by a hydrolysable linker, has demonstrated activity and is approved in metastatic triple-negative breast cancer and in metastatic hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancer. EVOKE-01 (NCT05089734) evaluated the efficacy and safety of SG vs docetaxel in patients with metastatic non-small cell lung cancer (NSCLC) after receiving platinum chemotherapy and anti-PD-(L)1 treatment. The study did not meet statistical significance for the primary endpoint of overall survival (OS) at final analysis; numerical improvement in OS was seen with SG vs docetaxel. To date, the biomarkers associated with the clinical efficacy of SG in NSCLC are not well characterized. We performed a retrospective analysis of exploratory biomarkers to evaluate their predictive/prognostic value. Methods: Exploratory biomarker analyses were conducted in the biomarker evaluable population (BEP; N=380), representing 63% of the intent-to-treat (ITT) population with biomarker data available. Trop-2 protein expression was assessed using the EPR20043 FLA IHC assay (Roche-Tissue Diagnostics) and scored by a pathologist based on H-scores. The clinical data used for biomarker analyses were from the study’s final analysis (cutoff date: 29NOV2023). Results: Baseline characteristics were comparable between BEP and ITT; similar to the ITT population, there was no statistically significant difference between treatments. Trop-2 protein was highly expressed in NSCLC tumor samples, consistent with previous observations. Trop-2 expression was similar in both treatment arms with a median H-score of 190 and was slightly higher in squamous vs non-squamous NSCLC. Trop-2 expression was also similar among subgroups of patients with different best responses (SD/PD vs CR/PR) to last prior anti-PD-(L)1 therapy. Analysis of Trop-2 correlation with clinical outcomes showed that higher Trop-2 expression did not predict better OS with SG vs docetaxel; median OS hazard ratios (95% CI) with SG vs docetaxel were 0.89 (0.60-1.32) and 0.96 (0.68-1.38) in the <190 and ≥190 Trop-2 H-score subgroups, respectively. Median OS was shorter in ≥190 vs <190 Trop-2 H-score subgroups with both SG (8.90 vs 11.79 mo) and docetaxel (9.76 vs 10.71 mo). Results were consistent in squamous and non-squamous subgroups. Conclusion: Exploratory biomarker analyses were conducted to identify potential biomarkers that are either predictive for SG or prognostic for NSCLC. Trop-2 was highly expressed in NSCLC, albeit not predictive of better OS with SG compared with docetaxel. Trop-2 may be a negative prognostic biomarker in this NSCLC population, independent of treatment received in the study. Citation Format: Marina Chiara Garassino, Peiwen Kuo, Niels Reinmuth, Nicolas Girard, Giannis Mountzios, Mariano Provencio, Yvonne Summers, Marcello Tiseo, Shan Tang, Riddhi Patel, Sabeen Mekan, Juliane M. Jürgensmeier. Potential prognostic/predictive biomarkers for sacituzumab govitecan in EVOKE-01 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB260.

Human trophoblast cell surface antigen 2 (TROP2) and programmed death ligand 1 (PD-L1) are often overexpressed in a variety of human cancers. Both anti-PD-L1 antibodies and TROP2-based antibody drug conjugates (ADCs) have shown significant clinical benefit, and a number of these agents, including atezolizumab and durvalumab (both anti-PD-L1 antibodies) and sacituzumab govitecan (an anti-TROP2-SN38 ADC), have been approved by the US FDA for certain cancer indications. The efficacy of these agents is, however, often limited by the unwanted on-target/off-tumor toxicities and the emergence of resistance of tumor cells. In this study, we engineered a humanized bispecific antibody (bsAb) simultaneously targeting both TROP2 and PD-L1 and produced several drug conjugates utilizing various linkers and cytotoxic payloads. The bsAb ADC binds efficiently to tumor cells that express either or co-express both TROP2 and PD-L1, trigger rapid ADC internalization, and induce potent tumor killing activity. Further, the bsAb ADC also effectively blocks PD1/PD-L1 interaction, and in parallel, induce PD-L1 internalization and down-regulation on tumor cell surface, resulting in significantly enhanced T cell activation for tumor cell killing. In multiple xenografted tumor models, the bsAb ADC demonstrated greater tumor inhibitory activity than their respective monospecific parent antibody ADCs. Taken together, our findings support further development of this bsAb ADC for the treatment of multiple TROP2- and/or PD-L1-expressing cancers, and of those patients who are refractory and/or resistant to TROP2 or PD-L1 single target-based therapies. Citation Format: Chuan Chen, Liang Tian, Chenpeng Su, Dandan Liu, Jiyuan Tian, Yujuan Li, Bing Yang, Yongxin Shan, Xiaoqian Chen, Jian Peng, Zhenping Zhu. Engineering and preclinical development of an anti-TROP2/PD-L1 bispecific antibody drug conjugate (ADC) for enhanced anti-tumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6072.

TPS6130 Background: Current treatment options for advanced or metastatic differentiated thyroid carcinoma (DTC) with vascular endothelial growth factor inhibitors provide clinical benefit, despite the fact that most patients will acquire treatment resistance, whereas, advanced or metastatic anaplastic thyroid carcinoma (ATC) still lacks effective treatment options. Trophoblast cell surface antigen 2 (TROP-2) is highly expressed at the membrane of DTC and ATC, while it is rarely expressed in normal tissues. Moreover, TROP-2 is associated with tumor aggressiveness and poor prognosis. Targeting TROP-2 with sacituzumab govitecan, an antibody-drug conjugate with a SN-38 payload, showed efficacy in other cancer types such as triple negative or HER positive breast cancer or urothelial cancer and may be an effective treatment for thyroid carcinoma. SETHY is the first clinical trial with antibody-drug conjugates in thyroid cancer. Methods: The SETHY trial is a single-arm, multicohort, prospective, phase 2 trial of sacituzumab govitecan in patients with advanced or metastatic radioactive-iodine refractory thyroid cancer being recruited in 10 hospitals in Spain. Patients are ≥ 18 years, ECOG 0-1, should have recovered from any prior toxicity and have an adequate organ function. Patients will be included in two cohorts: DTC after progression (PD) to 1-3 prior systemic therapies (cohort 1) or ATC in 1st-line treatment or after failure of any systemic therapy (Cohort 2). Prior topoisomerase 1 inhibitors are not permitted. All patients will receive sacituzumab govitecan (10 mg/kg intravenously) on Days 1 and 8 of every 21-days cycle, until PD, death, study withdrawal, or unacceptable toxicity. Computed tomography (CT) or magnetic resonance imaging (MRI) scans and blood monitoring of tumor markers are performed every 12 weeks (Q12W) until PD. The primary endpoint is objective response rate (ORR) according to RECIST v1.1. Secondary endpoints include disease control rate, duration of response, progression-free survival, overall survival, safety, and quality of life (assessed through EORTC QLQ-C30 at baseline and Q12W until PD). Archival tumor samples will be collected at screening for retrospective central evaluation of TROP-2 expression levels and ancillary studies. The study uses a Simmon-II design considering a ORR of 5% as null hypothesis and an alternative ORR of 20% (α=0.1 one sided, β=0.2). In total, the study requires a total of 21 patients per cohort; 12 in the 1st stage and, if at least one response is reported, 9 additional in the 2nd stage. The study is approved and open to patient selection in Spain. Clinical trial identification: EU CT: 2023-504898-20-00 / NCT06235216 Clinical trial information: NCT06235216 .

Introduction Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related mortality worldwide. Despite advancements in targeted therapies and immune checkpoint inhibitors, many patients with advanced NSCLC experience disease progression, necessitating novel therapeutic approaches like antibody-drug conjugate (ADC), Areas Covered Sacituzumab govitecan, a trophoblast cell surface antigen 2 (Trop-2) – directed ADC, has emerged as a potential treatment for advanced NSCLC This review evaluates its mechanism of action, clinical efficacy, safety profile, and potential in combination therapies, particularly in heavily pretreated patients. A literature search was conducted using PubMed with keywords ‘sacituzumab govitecan’ and ‘lung cancer,’ incorporating relevant studies, including the EVOKE-01 trial. Expert Opinion Sacituzumab govitecan offers a promising alternative for patients unresponsive to conventional treatments. While it demonstrates encouraging response rates and manageable toxicity, further research is needed to refine patient selection and optimize combination strategies. Ongoing trials, such as KEYNOTE-D46/EVOKE-3 May 2001define its role in first-line NSCLC treatment.

Antibody-drug conjugates targeting TROP-2: Clinical development in metastatic breast cancer

Background Trophoblast cell surface antigen 2 (TROP2) is frequently overexpressed in various cancers and is associated with poor prognosis. While TROP2-targeted antibody-drug conjugates (ADCs), such as sacituzumab govitecan, sacituzumab tirumotecan, and datopotamab deruxtecan achieved clinical success, the mechanisms underlying resistance to these therapies remain incompletely understood. Consequently, the full therapeutic potential of TROP2 ADC has yet to be comprehended. Methods We developed R7059-DXD, a novel TROP2-targeted ADC featuring an antibody that binds an epitope distinct from sacituzumab and datopotamab. The structural basis of epitope recognition was elucidated using cryo-electron microscopy (cryo-EM), complemented by binding affinity analyses across multiple surface-expressed TROP2 variants. Functional activity was systematically evaluated through in vitro ADCC assays, in vitro ADC-mediated killing assays, and in vivo efficacy studies in tumor models, including resistant lines. Results The R7059 antibody exhibited high binding affinity across multiple TROP2 variants, addressing a key resistance mechanism. The cryo-EM structure analysis revealed that the R7059 epitope lies in the N-terminal domain of TROP2 and is distinct from the sacituzumab and datopotamab epitopes. Functionally, R7059 demonstrated potent anti-tumor activity through both ADCC-dependent and independent mechanisms, suggesting additional signaling effects. The R7059-ADC demonstrated robust efficacy in multiple preclinical tumor models, including those resistant to approved TROP2 ADCs. Conclusions R7059-DXD is a differentiated, epitope-distinct TROP2-targeted ADC with the potential to overcome resistance to existing therapies. These findings support its further clinical development as a novel treatment for TROP2-expressing malignancies, including in patients previously treated with sacituzumab- or datopotamab-based regimens.

5031 Background: Trophoblast cell surface antigen 2 (TROP-2) is a tumor associated antigen overexpressed in several malignancies including breast and urothelial cancer. The TROP-2 antibody-drug conjugate (ADC) Sacituzumab govitecan is approved for treatment of metastatic breast cancer. The expression of TROP-2 in GCT is unknown. We present immunohistochemistry results of TROP-2 expression in GCT. Methods: Patients who underwent resection for GCT at Indiana University were included. Sixty formalin-fixed paraffin-embedded (FFPE) GCT samples were available. FFPE slides were selected from differing GCT histology and surgical sites including primary tumor, retroperitoneal lymph node, and distant metastases. Immunohistochemical (IHC) staining for TROP-2 (clone 1, mouse monoclonal, Enzo Life Sciences) was conducted and scored by intensity on a 0-3 scale by an experienced pathologist. Results: Samples from 60 individual specimens were available for IHC analysis. TROP2 expression was detected in 29 (48%) of these samples. Intensity expression differed from pure seminoma, mixed non-seminoma (NSGCT), teratoma, yolk sac tumor, and choriocarcinoma samples. Both primary and metastatic samples had TROP-2 expression of varying degrees. Conclusions: TROP-2 expression varies across histology in GCT. Seminoma appears to have the lowest expression of TROP-2. Higher TROP-2 expression was noted in choriocarcinoma and yolk sac tumor samples indicating potential as a target in these histologic subtypes in future clinical trials. Detectable TROP-2 by histology. Sample histology (N) Total detectable TROP-2 expression (%) 3+ 2+ 1+ Seminoma (20) 3 (15) 2 1 NSGCT (19) 12 (63) 9 (6*) 2* 1* Teratoma (9**) 6 (66) 3* 3* Yolk sac (9) 5 (56) 2 3 Choriocarcinoma (3) 3 (100) 1 1 1 *In epithelial elements of teratoma. **Three negative samples with only small fragments of teratoma and false negative may be present.

Background: The trophoblast cell-surface antigen 2 (TROP2) is associated with enhanced tumor proliferation and poor prognosis in breast cancer. TROP2 overexpresses on various epithelial cancer cell surfaces, and is commonly found in prostate, colon, pancreas, lung, and breast cancer. Therefore, anticancer strategy targeting TROP2 may be a potential treatment option for patients with metastatic triple-negative breast cancer (TNBC). Sacituzumab govitecan, a Trop-2-directed antibody drug conjugate (ADC), has shown significant benefits associated with progression-free and overall survival compared to standard chemotherapy for treating metastatic TNBC; however, its toxic effects were more frequent than that of chemotherapy (NCT02574455). In this study, we discovered TROP2 target peptides with T-helper 1 (Th1) polarization and anticancer efficacy. We then evaluated the anti-tumor efficacy of these epitopes and possibility of co-administration with ADC in a TNBC murine model. Materials and Methods: Th1 peptides were identified using the Th-Vac® platform and the predictive binding affinity ranking that indicates potential immunogenicity points of interest for HLA class II. Human peripheral blood mononuclear cell (PBMC) Th1-specific polarization-induced activity and in vivo immunogenicity (Module 2b) were evaluated using flow cytometry and ELISpot analysis. The anti-tumor efficacy of the selected Th1 peptide was evaluated against MDA-MB-23 inoculated athymic Balb/c mice. Each peptide was administered intradermally once weekly for a total of four times at a concentration of 100 μg/head. Sacituzumab govitecan (0.81 mg/kg) was administered intravenously once weekly, for a total of two times. Results: Ten peptides with high affinity for HLA class II were selected, and three epitopes that induce differentiation of T cells secreting TROP2-specific IFN-γ were subsequently selected. These epitopes (p1, p3 and p6) showed tumor growth inhibition efficacy of 52.4%, 38.5%, and 57.2%, respectively, compared to the control (vehicle) group in the TNBC tumor-bearing mice. The cocktail vaccine (AST-07X), which combined these epitopes, was the most dominant at 65.4%. The anti-tumor efficacy of the combination group of the cocktail vaccine and ADC was 77.4% compared with the control group, showing a potent synergistic effect compared to the 46.1% anti-tumor efficacy of the ADC-mono group. Conclusion: AST-07X that induce TROP2-specific Th1 anticancer immune responses, showed sufficient anti-tumor efficacy; these effects were evident under immunodeficient conditions, such as those of TNBC tumor-bearing athymic mice. Synergy effects were also induced via combined ADC administration. We are currently conducting further research on humanized mice to address the limitations of the immunodeficient murine model. Citation Format: Jinho Kang, Hyo-Hyun Park, Jin Kyeong Choi, Seong-Yong Jang, Min-Ah Kim, Myeong-Kyu Park, Ashley Youngmin Kim, Eunkyo Joung, Hun Jung. The anti-tumor efficacy of Th1-specific TROP2 vaccine (AST-07X) in a triple-negative breast cancer murine model [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 6757.

Trophoblast cell-surface antigen 2 (TROP2) is a cell surface glycoprotein that plays a significant role in the self-renewal, proliferation, invasion and transformation of tumor cells, and is highly expressed in a variety of tumors. At present, TROP2 has become an important target for the research and development of Antibody-drug conjugates (ADCs) in the field of lung cancer. Although sacituzumab govitecan, datopotamab deruxtecan and sacituzumab tirumotecan are all TROP2-targeted ADCs, there are certain differences in their drug structures. These differences may have led to the distinctions in their anti-tumor activity and safety. This study aims to review the similarities and differences among these three drugs, with the expectation of providing some assistance for the selection of clinical medication. The key words Sacituzumab govitecan/IMMU-132, Datopotamab deruxtecan/DS-1062a and Sacituzumab tirumotecan/SKB264 retrieved Medline/PubMed, Google Scholar, Web of Science and ScienceDirect databases until September 25, 2025. Articles about pharmacokinetics, pharmacodynamics, drug safety and other aspects were selected to systematically summarize. These three TROP2 ADCs have many similarities in terms of pharmacokinetics, pharmacodynamics and common treatment-related adverse events. However, there are some differences in the efficacy of combination with immunotherapy drugs and treatment-related adverse events over grade 3. There are differences in pharmacological effects, efficacy, and incidence of adverse events among sacituzumab govitecan, datopotamab deruxtecan, and sacituzumab tirumotecan. For patients with EGFR-mutated progression after targeted therapy or driver gene negative advanced non-small cell lung cancer, the individualized optimization of TROP2 ADCs treatment can obtain the greatest benefit.