tumor associated calcium signal transducer 2

Overview

Tumor-associated calcium signal transducer 2 (TROP2), encoded by the TACSTD2 gene and also known as trophoblast cell-surface antigen 2 (Trop-2), is a type I transmembrane glycoprotein that was originally identified on trophoblast cells of the placenta. It functions as a calcium signal transducer and is implicated in the regulation of cell proliferation, survival, and adhesion. Under normal physiological conditions, TROP2 expression is restricted to a limited set of epithelial tissues; however, it is broadly and frequently overexpressed across a wide range of solid tumors, including non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), pancreatic cancer, and breast, gastric, and urothelial carcinomas. This tumor-enriched expression pattern, combined with its extracellular accessibility as a membrane-bound antigen, makes TROP2 a highly attractive therapeutic target.

The protein's association with cancer invasiveness and poorer patient outcomes has driven extensive efforts to exploit it as an antibody-drug conjugate (ADC) target. Several TROP2-directed ADCs have advanced through clinical development, with at least one receiving regulatory approval from both the Food and Drug Administration (FDA) and China's National Medical Products Administration (NMPA) for use in patients with acquired resistance to third-generation EGFR tyrosine kinase inhibitors (TKIs). Beyond ADCs, TROP2 is now being explored in radioimmunotherapy, bispecific antibody formats, and proteolysis-targeting chimera (PROTAC)-based platforms, reflecting its versatility as an oncological target.

Focus of Latest Publications

Recent publications have continued to evaluate tumor associated calcium signal transducer 2 (TROP2/TACSTD2) as a clinically relevant surface target across several cancers, especially in the context of antibody-drug conjugates (ADCs) and biomarker selection. In ovarian cancer, TROP2 expression was assessed alongside HER2 and nectin-4 across histotypes to determine whether target abundance varies by disease subtype and could inform patient selection for ADC-based therapy. In metastatic breast cancer, serial circulating tumor cell (CTC) imaging was used to monitor TROP2 and HER2 during treatment with TROP2- or HER2-directed ADCs, showing marked heterogeneity of target expression at the single-cell level and indicating that baseline TROP2 levels on CTCs did not predict depth of response.

Several studies linked TROP2 to treatment response or resistance biology. In pancreatic ductal adenocarcinoma, prolonged Kras-MAPK inhibition induced an interferon/NF-κB-driven cell-state transition with EMT features, accompanied by marked upregulation of TROP2; the authors reported that combining the TROP2-directed ADC sacituzumab govitecan with Kras or ERK inhibitors significantly suppressed tumor growth in xenograft models. In metastatic prostate cancer treated with 177Lu-PSMA-617, plasma extracellular vesicle proteomics identified Trop-2 among several cell-surface proteins associated with worse overall survival and correlated with tumor burden measures, supporting its potential as part of a liquid-biopsy biomarker panel. In small cell lung carcinoma, TROP2 was included among therapeutic targets examined in paired biopsy samples to compare target protein expression in de novo and transformed disease, reflecting ongoing interest in its role in patient stratification.

TROP2 has also been incorporated into emerging therapeutic strategies beyond ADC monotherapy. A phase 3 trial in PD-L1-positive advanced non-small-cell lung cancer evaluated sacituzumab tirumotecan, a TROP2-targeting ADC, in combination with pembrolizumab as first-line treatment. In another preclinical study, TROP2 was used as a tumor-specific receptor to build a bispecific antibody designed to target Frizzled and inhibit Wnt signaling selectively in tumor cells while sparing normal intestinal tissue. Across these reports, TROP2 is consistently presented as a surface marker with therapeutic and biomarker potential, but with expression heterogeneity and context dependence that may limit simple expression-based prediction of benefit.

Key Publications

NEWJul Human epidermal growth factor receptor-2, nectin-4, and trophoblast cell surface antigen-2 expression varies significantly across ovarian cancer histotypes. (Taiwanese journal of obstetrics & gynecology, 2026, PMID 42362263): "Antibody-drug conjugates (ADCs) targeting human epidermal growth factor 2 (HER2), nectin-4, and trophoblast cell surface antigen 2 (TROP2) have shown efficacies in various cancers and may benefit patients with OC."
NEWJun Dynamic monitoring of antibody drug conjugates targeting TROP2 or HER2 in breast cancer using circulating tumor cells. (Proceedings of the National Academy of Sciences of the United States of America, 2026, PMID 42308036): "ADCs against TROP2 (Sacituzumab govitecan) or HER2 (T-DXd) have demonstrated efficacy in metastatic breast cancer, yet paradoxically, outside of HER2-amplified breast cancers, expression levels of these breast cancer-enriched epitopes in tumor biopsies have not been strongly correlated with clinical response."
May Sacituzumab tirumotecan plus pembrolizumab versus pembrolizumab in PD-L1-positive advanced non-small-cell lung cancer (OptiTROP-Lung05): interim analysis of a randomised, open-label, phase 3 trial. (Lancet (London, England), 2026, PMID 42214392): "Sacituzumab tirumotecan (sac-TMT), a trophoblast cell-surface antigen 2-targeting antibody-drug conjugate, combined with programmed death 1 (PD-1) or programmed death ligand 1 (PD-L1) inhibitors, has shown promising antitumour activity as first-line therapy for non-small-cell lung cancer (NSCLC) in early-phase studies."
May Tumor-targeted bispecific antibodies effectively inhibit oncogenic pathways while minimizing toxicity. (Science advances, 2026, PMID 42172336): "Using single-cell technologies, we identified tumor-specific receptors, including tumor-associated calcium signal transducer 2 (TROP2), which are absent in cells reliant on Wnt signaling."
Jun Comparative analysis of therapeutic target protein expression in de novo and transformed small cell lung carcinomas using paired biopsy samples. (Lung cancer (Amsterdam, Netherlands), 2026, PMID 42013561): "...data on other targetable proteins such as trophoblast cell-surface antigen 2 (TROP2) and B7-H3 remain limited."
May Plasma extracellular vesicle proteomics nominates candidate biomarkers of 177Lu-PSMA-617 outcomes in metastatic prostate cancer patients. (Cell reports. Medicine, 2026, PMID 42013849): "We identify 5,137 EV-derived proteins, including the cell-surface targets PSMA, B7-H3, Trop-2, and STEAP1, with high levels of these proteins associating with worse overall survival (OS)."
Jul Prolonged KRAS-MAPK Inhibition Induces Interferon Signaling That Promotes Cell State Transition and Confers Therapeutic Vulnerabilities. (Cancer research, 2026, PMID 42008116): "EMT induction was accompanied by marked upregulation of TROP2 (TACSTD2), an NF-κB target gene enriched in basal-like PDAC cell states."
Apr ADC target profiling in NSCLC: Generalizable AI separates TROP-2 and cMET phenotypes. (Clinical cancer research : an official journal of the American Association for Cancer Research, 2026, PMID 41945491): "Antibody drug conjugates (ADCs) targeting TROP-2 and cMET are entering clinical trials in NSCLC."
Apr The emerging role of antibody-drug conjugates in EGFR-mutant non-small cell lung cancer with acquired resistance to third-generation EGFR tyrosine kinase inhibitors. (Journal of controlled release : official journal of the Controlled Release Society, 2026, PMID 41730505): "In recent years, multiple antibody-drug conjugates (ADCs) have been developed and evaluated in this setting, with trophoblast cell-surface antigen 2 ADCs recently receiving approval from the National Medical Products Administration and the Food and Drug Administration for use after EGFR-TKI resistance."