High TROP2 Expression Research Articles

Biomarker analyses in the phase III ASCENT study of sacituzumab govitecan versus chemotherapy in patients with metastatic triple-negative breast cancer

The pivotal phase III ASCENT trial demonstrated improved survival outcomes associated with sacituzumab govitecan (SG), an anti-trophoblast cell-surface antigen 2 (anti-Trop-2) antibody-drug conjugate linked with the topoisomerase-inhibitor SN-38, over single-agent chemotherapy treatment of physician's choice (TPC) in previously treated metastatic triple-negative breast cancer (mTNBC). This prespecified, exploratory biomarker analysis from the ASCENT trial evaluates the association between tumor Trop-2 expression and germline BRCA1/2 mutation status with clinical outcomes. Patients with mTNBC refractory to or progressing after two or more prior chemotherapies, with one or more in the metastatic setting, were randomized to receive SG (10 mg/kg intravenously days 1 and 8, every 21 days) or TPC (capecitabine, eribulin, vinorelbine, or gemcitabine) until disease progression/unacceptable toxicity. Biopsy or surgical specimens were collected at study entry to determine Trop-2 expression level using a validated immunohistochemistry assay and histochemical scoring. Germline BRCA1/2 mutation status was collected at baseline. Of 468 assessable patients, 290 had Trop-2 expression data [64% (n= 151 SG) versus 60% (n= 139 TPC)] and 292 had known BRCA1/2 mutation status [63% (n= 149 SG) versus 61% (n= 143 TPC)]. Median progression-free survival in SG- versus TPC-treated patients was 6.9, 5.6, and 2.7 months versus 2.5, 2.2, and 1.6 months for high, medium, and low Trop-2 expression, respectively. Median overall survival (14.2, 14.9, and 9.3 months versus 6.9, 6.9, and 7.6 months) and objective response rates (44%, 38%, and 22% versus 1%, 11%, and 6%) were numerically higher with SG versus TPC in patients with high, medium, and low Trop-2 expression, respectively. Efficacy outcomes were numerically higher with SG versus TPC in patients with and without germline BRCA1/2 mutations. SG benefits patients with previously treated mTNBC expressing high/medium Trop-2 compared with standard-of-care chemotherapy and regardless of germline BRCA1/2 mutation status. The small number of patients with low Trop-2 expression precludes definitive conclusions on the benefit of SG in this subgroup.

Correlation of Trop-2 expression with clinicopathological characteristics, sTILs, AR expression and outcome in primary TNBC.

e12558 Background: Trophoblast cell-surface antigen-2 (Trop-2) is a transmembrane calcium signal transducer highly expressed in multiple tumor types including breast cancer. Trop-2 overexpression is associated with poor survival. Given the approval of sacituzumab govitecan in advanced triple-negative breast cancer (TNBC), Trop-2 emerges as an important target for antibody-drug conjugates. Limited data exist about correlations of Trop-2 expression with clinicopathological characteristics and outcome in early TNBC. Methods: We included 127 patients with early TNBC, treated with primary surgery at UZLeuven from 2005-2017. Trop-2 expression was determined with IHC (ab227689, Abcam) on whole slide tumor sections from resection specimens and assessed as continuous (H-score 0-300) and categorical (high 201-300, medium 100-200 and low < 100) variables. Stromal tumor infiltrating lymphocytes (sTIL; low, intermediate and high), mitotic score and androgen receptor (AR) expression (1% or 10%-cutoff) were scored. We assessed associations between Trop-2 expression and age, BMI, BRCA status, tumor grade and size, lymphovascular invasion (LVI), DCIS, nodal status, sTILs, AR, mitotic index and outcome (Invasive disease free survival and breast cancer specific survival). Results: The median age at diagnosis was 51y (range 26-80y) and the median follow-up 8.5y. Low, medium and high Trop-2 expression was seen in 50%, 37% and 13% of cases. AR was positive in 32% of cases (10%-cutoff). Higher Trop-2 expression was correlated with age (ρ = 0.192, p = 0.03) and inversely correlated with mitosis/mm² (ρ = -0.2, p = 0.02). Patients with high Trop-2-expression were older compared to patients with low Trop-2-expression (median 58 vs 47 years, p = 0.02). LVI was more frequent in Trop-2-high (65%) compared to TROP-2-medium (15%) or -low (16%) (p < 0.001). Median mitosis/mm² was higher in Trop-2-low (14) compared to Trop-2-medium (10) and -high (8) (p = 0.004). Patients in Trop-2-high subgroup had more nodal involvement (53%) compared to Trop-2-medium (23%) and -low (21%) (p = 0.03). There was no correlation between Trop-2 expression and sTILs, AR or outcome. Conclusions: In this patient cohort with TNBC treated with upfront surgery, higher Trop-2 expression was correlated with older age, with more LVI and nodal involvement, while mitosis/mm² were higher in tumors with low Trop-2 expression. Trop-2 expression was not correlated with sTILs, AR or outcome. Limited numbers of events warrant caution in interpretation.

Abstract GS3-06: Biomarker evaluation in the phase 3 ASCENT study of sacituzumab govitecan versus chemotherapy in patients with metastatic triple-negative breast cancer

Abstract Background: Trophoblast cell-surface antigen-2 (Trop-2) is highly expressed in many epithelial tumors, including triple-negative breast cancer (TNBC). Sacituzumab govitecan (SG) is an antibody-drug conjugate composed of an anti-Trop-2 antibody coupled to SN-38, an active metabolite of irinotecan, via a unique hydrolyzable linker that allows for SN-38 release intracellularly and in the tumor microenvironment (bystander effect). Preclinical studies have shown a great range of efficacy with SG in mice bearing tumors with low, moderate, and high Trop-2 expression levels. We report subgroup analyses by Trop-2 expression from ASCENT, a randomized, phase 3 confirmatory study of SG versus standard-of-care chemotherapy in patients with metastatic TNBC (mTNBC). Methods: In the global, multicenter, open-label, phase 3 ASCENT study (NCT02574455), 529 patients with mTNBC refractory to or relapsing after at least 2 prior chemotherapies were randomized 1:1 to receive SG (10 mg/kg intravenously on days 1 and 8 every 21 days) or single-agent treatment of physician’s choice (capecitabine, eribulin, vinorelbine, or gemcitabine) until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS) measured by central independent review per RECIST v1.1. Secondary endpoints included objective response rate (ORR) per RECIST v1.1, duration of response, overall survival (OS), and safety. Exploratory endpoints included biomarker assessments, including Trop-2 and BRCA1/2. Trop-2 expression was assessed using a validated immunohistochemistry assay. Results: Subgroup analyses by biomarker expression including Trop-2 and BRCA1/2 were performed, and outcomes by PFS, OS, ORR, and safety results will be reported. Conclusions: These analyses will provide further insights into the relationship of Trop-2 expression and the activity of SG in previously treated patients with mTNBC. Citation Format: Sara A. Hurvitz, Sara M. Tolaney, Kevin Punie, Delphine Loirat, Mafalda Oliveira, Kevin Kalinsky, Amelia Zelnak, Philippe Aftimos, Florence Dalenc, Sagar Sardesai, Erika Hamiltion, Priyanka Sharma, Sabela Recalde, Eva Ciruelos Gil, Tiffany Traina, Joyce O'Shaughnessy, Javier Cortés, Michaela Tsai, Linda Vahdat, Véronique Diéras, Lisa Carey, Hope S. Rugo, David M. Goldenberg, Quan Hong, Martin Olivo, Loretta M. Itri, Aditya Bardia. Biomarker evaluation in the phase 3 ASCENT study of sacituzumab govitecan versus chemotherapy in patients with metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS3-06.

Abstract A027: Combination of TROP2 and SLFN11 as the sensitivity biomarkers for DS-1062a, a novel TROP2-targeting antibody-drug conjugate with a novel DNA topoisomerase I inhibitor DXd

Abstract Background: DS-1062a is a TROP2-targeting antibody-drug conjugate with Daiichi-Sankyo DXd technology. DS-1062a is expected to deliver DXd, a derivative of Exatecan, to TROP2 highly expressed tumors such as epithelial cancers with stronger anti-tumor effect and safer profile than the systemic chemotherapy. SLFN11 has been reported as a sensitivity biomarkers of DNA topoisomerase I inhibitors in several cancers. In this research, we elucidated the potency of combination of TROP2 and SLFN11 as a sensitive biomarkers of DS-1062a sensitivity using in vitro and in vivo preclinical models. Materials and Methods: Growth inhibition effect of DS-1062a and DXd were tested using 39 cell lines of various cancer types and correlation between DS-1062a efficacy and both TROP2 and SLFN11 mRNA level was elucidated. To confirm the contribution of SLFN11 expression to DS-1062a sensitivity, SLFN11 was knocked down in 5 of TROP2 and SLFN11 expressed cell lines and changes of growth inhibition effects of DS-1062a and DXd were evaluated. DS-1062a efficacy were also evaluated in 25 PDX (Patient-derived xenograft) models which express various levels of TROP2 and SLFN11 and relationship of sensitivity of each tumor to DS-1062a and TROP2 and SLFN11 mRNA levels was analyzed. Results: In vitro tumor cell growth inhibition effect of DS-1062a was observed in the most of TROP2 highly expressed cell lines. However, DS-1062a showed weak efficacy in some cell lines with high TROP2 expression, which have relatively low sensitivity to DXd. Correlation analysis between DXd efficacy and gene expression suggested cell lines with low sensitivity tend to express limited level of SLFN11. Knock down of SLFN11 weakened in vitro tumor cell growth inhibition effect of both DS-1062a and DXd in cell lines with high expression of SLFN11 level. Furthermore, in vivo study with 25 PDX models, strong drug efficacy of DS-1062a was frequently observed in both TROP2 and SLFN11 expressed tumor. Conclusion: We revealed that SLFN11 is one of the sensitivity biomarkers other than TROP2 expression levels against DS-1062a. This finding suggests combination of TROP2 and SLFN11 could be a promising biomarker to predict antitumor effect of DS-1062a. Citation Format: Satoru Yasuda, Daisuke Okajima, Tadashi Toki, Junko Yamaguchi, Tsuyoshi Karibe, Tomomichi Fujitani, Takashi Nakada, Yutaka Noguchi, Masato Murakami. Combination of TROP2 and SLFN11 as the sensitivity biomarkers for DS-1062a, a novel TROP2-targeting antibody-drug conjugate with a novel DNA topoisomerase I inhibitor DXd [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A027. doi:10.1158/1535-7163.TARG-19-A027

Abstract 3193: Treatment of high Trop-2-expressing triple-negative breast cancer (TNBC) with sacituzumab govitecan (IMMU-132) overcomes homologous recombination repair (HRR) rescue mediated by Rad51

Abstract Purpose: IMMU-132 is an antibody-drug conjugate composed of a humanized anti-Trop-2 IgG conjugated via a cleavable linker to SN-38, a topoisomerase I inhibitor and active component of irinotecan. It is currently under clinical investigation in a range of solid tumors (NCT01631552). We investigated the hypothesis that IMMU-132, through its targeting of Trop-2 in solid tumors, will be superior to irinotecan in overcoming Rad51-mediated HRR repair of DNA breaks in TNBC tumors with high Trop-2 expression. Methods: Rad51 and DNA-breaks (γ-H2A.X) were determined by Western blot. Cells with different Trop-2 levels were exposed to IMMU-132 for 24 h (25 - 100 nM SN-38 equivalents), including squamous cell lung carcinoma (SK-MES-1; ~30,000 Trop-2/cell) and TNBC (HCC1806, ~90,000 Trop-2/cell and MDA-MB-231, ~30,000 Trop-2/cell). Also, two Trop-2-transfectants of MDA-MB-231, designated C13 and C39 (4- and 25-fold higher Trop-2 levels, respectively), were likewise exposed to IMMU-132. Mice bearing MDA-MB-231, C13, or C39 tumors were treated with irinotecan (MTD, 40 mg/kg; q2dx5) or IMMU-132 (0.5 mg; 9 μg SN-38 equivalent, twice wkly x 4). Tumors were measured and mice weighed twice weekly. Study survival endpoint was tumor progression to >1.0 cm3. Results: SK-MES-1 and HCC1806 are sensitive to IMMU-132 therapy whereas MDA-MB-231 is resistant. IMMU-132 mediated a >2-fold increase in Rad51 levels in MDA-MB-231 cells, but had no effect in SK-MES-1 or HCC1806. At 25 nM IMMU-132, there were lower levels of DNA breaks detected in MDA-MB-231 relative to SK-MES-1 and HCC1806 (2-fold increase in MDA-MB-231 vs. >3-fold). At higher concentrations of IMMU-132 (100 nM), all 3 cell lines demonstrated similar levels of DNA breaks (~5-fold above background), suggesting that higher levels of SN-38 can overcome Rad51-mediated repair. Both the C13 and C39 clones had a similar response as parental MDA-MB-231 upon IMMU-132 exposure. Mice bearing MDA-MB-231, C13, or C39 tumors treated with irinotecan demonstrated significant improvements in median survival times (MST) compared to saline (P<0.0009). As expected, IMMU-132 was no different than saline in mice bearing MDA-MB-231 tumors (MST=21d and 19.5d, respectively). However, in mice bearing high Trop-2 C13 and C39 tumors, IMMU-132 provided a significant survival benefit compared to irinotecan-treated mice (MST>70d vs. 35d, respectively for C13 and >70d vs. 28d for C39; P<0.0007), supporting the hypothesis that IMMU-132 is able to deliver more SN-38 to tumors with high Trop-2 than can be achieved by irinotecan, and can thus overcome Rad51-mediated HRR. Conclusion: IMMU-132, with its unique SN-38-delivery platform, has the potential to provide clinical benefit both to chemo-sensitive solid tumors with low Trop-2 expression, as well as to chemo-resistant tumors with high Trop-2 expression. Citation Format: Thomas M. Cardillo, Ali A. Mostafa, Diane L. Rossi, Donglin Liu, Chien-Hsing Chang, Robert M. Sharkey, David M. Goldenberg. Treatment of high Trop-2-expressing triple-negative breast cancer (TNBC) with sacituzumab govitecan (IMMU-132) overcomes homologous recombination repair (HRR) rescue mediated by Rad51 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3193. doi:10.1158/1538-7445.AM2017-3193

Abstract CT155: Phase 2 study of sacituzumab govitecan (IMMU-132), an anti-Trop-2/SN-38 antibody-drug conjugate (ADC), in patients with pretreated metastatic small-cell lung cancer (mSCLC)

Abstract Introduction: Sacituzumab govitecan (IMMU-132) is an antibody-drug conjugate (ADC) delivering SN-38, a topoisomerase-1 inhibitor, to mSCLC cells expressing Trop-2. We are studying the safety/tolerability and efficacy of IMMU-132 in patients with relapsed/refractory mSCLC who had received a platinum-containing first-line regimen. Experimental Procedure: Patients received 8 or 10 mg/kg IV IMMU-132 on days 1 and 8 of repeated 21-day cycles. Objective tumor response (ORR) was determined by RECISTv1.1 in patients receiving at least one treatment cycle, and progression-free survival (PFS) and overall survival (OS) in all patients by Kaplan-Meier methods. (ClinicalTrials.gov, NCT01631552) Summary of New Unpublished Data: A total of 53 patients (23/30 M/F, median 63 years old) with 1-7 (median 2) prior lines of therapy were enrolled between November, 2013 and June, 2016. Immunohistochemistry of evaluable archival tumor specimens for Trop-2 expression (N=26) showed 92% positivity (61% moderately to strongly positive). They received up to 32 treatment cycles (median 5); the most frequent Grade >3 adverse events were neutropenia (34%), fatigue (13%) and diarrhea (9%). Four patients did not complete one cycle of treatment. In the other 49 patients (14 at 8 mg/kg, 35 at 10 mg/kg), there were 7 confirmed PRs and 21 SDs as best response. The resulting ORR rate was 14% (7/49), with a median duration and time-to-progression of a response of 4.0 and 7.6 mos, respectively, and the clinical benefit rate (PR+SD >4 mos) was 35% (17/49). The ORR rate was similar in pts who were sensitive (>3 mos response) or resistant (<3 mos) to 1st-line therapy [13% (3/23) vs 15% (4/26), respectively]. In 2nd-line setting, IMMU-132 had a confirmed ORR rate of 14% (3/21), and a clinical benefit rate of 38% (8/21). This compares well to recent results with topotecan having an ORR of 13-16% in 2nd-line. Comparing dose levels, ORR was 17% (6/35) with 10 mg/kg vs 7% (1/14) with 8 mg/kg, with little difference in toxicity. Median PFS and OS in all 53 patients was 3.7 mos (95% CI, 2.0 - 4.3) and 7.0 mos (95% CI, 5.5 - 8.3), respectively, and included 6 long-term survivors (12.7 - 25.4 months). No antibody response to the ADC or antibody was detected despite multiple therapy cycles. Conclusion: These interim results demonstrate encouraging activity in patients with late-stage mSCLC having a high expression of Trop-2. Even after failing 1st-line platinum chemotherapy or 2nd-line topotecan therapy, IMMU-132 showed promising activity, and has a manageable toxicity profile. IMMU-132 given at 10 mg/kg on day 1 and 8 of a 3-week cycle was selected for further clinical evaluation in this population. Citation Format: Jhanelle E. Gray, Rebecca S. Heist, Alexander N. Starodub, D. Ross Camidge, Ebenezer Kio, Gregory Masters, W. Thomas Purcell, Michael J. Guarino, Jamal Misleh, Charles J. Schneider, Bryan J. Schneider, Allyson J. Ocean, Tirrell Johnson, Leena Gandhi, Kevin Kalinsky, Serengulam V. Govindan, Pius Maliakal, Boyd Mudenda, William A. Wegener, Robert M. Sharkey, David M. Goldenberg. Phase 2 study of sacituzumab govitecan (IMMU-132), an anti-Trop-2/SN-38 antibody-drug conjugate (ADC), in patients with pretreated metastatic small-cell lung cancer (mSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT155. doi:10.1158/1538-7445.AM2017-CT155

Association of tumor TROP2 expression with prognosis varies among lung cancer subtypes.

TROP2 is a transmembrane glycoprotein that is overexpressed in various cancers. Emerging evidence suggests that TROP2-targeting therapies are efficacious and safe in patients with multiple prior treatments. TROP2 is a promising target for lung cancer treatment; however, little is known regarding the association of TROP2 expression with clinicopathological/molecular features, including prognosis, in lung cancer. We examined consecutive cases of adenocarcinoma, squamous cell carcinoma (SqCC), and high-grade neuroendocrine tumor (HGNET) for the membranous expression of TROP2 using immunohistochemistry. High TROP2 expression was observed in 64% (172/270) of adenocarcinomas, 75% (150/201) of SqCCs, and 18% (21/115) of HGNETs. Intriguingly, the association of TROP2 expression with mortality was dependent on the lung cancer subtype. High TROP2 expression was associated with higher lung cancer-specific mortality in adenocarcinomas [univariable hazard ratio (HR) = 1.60, 95% confidence interval (CI) = 1.07–2.44, P = 0.022)], but not in SqCCs (univariable HR = 0.79, 95% CI = 0.35–1.94, P = 0.79). In HGNETs, high TROP2 expression was associated with lower lung cancer-specific mortality in both univariable and multivariable analyses (multivariable HR = 0.13, 95% CI = 0.020–0.44, P = 0.0003). Our results suggest a differential role for TROP2 in different lung cancer subtypes.

Trop2 as an oncogene in gastric cancer by regulating PI3K/Akt signaling pathway

High Trop2 expression relates to aggressive tumor behavior and contributes to poor overall survival rates in gastric cancer (GC) patients. However, little is known about the molecular mechanism of Trop2 in the carcinogenesis of GC. We found that over-expressed Trop2 induced cell proliferation and clone formation, inhibited cell apoptosis and induced S cell cycle arrest in GC cell lines, meanwhile, knockdown Trop2 inhibited cell proliferation and clone formation, induced cell apoptosis and inhibits S cell cycle arrest in vitro. Moreover, Trop2 depletion inhibited tumor growth , the anti-tumor rate in this report being 22.53% in vivo. In addition, Trop2 activated the PI3K/Akt signaling pathway to promote GC malignant progression. These results indicated that Trop2 is a critical regulation factor in the progression of GC, which may help to lead a novel insight into understanding the mechanism of the Trop2 in the pathogenesis of GC.

High expression of TROP2 characterizes different cell subpopulations in androgen-sensitive and androgen-independent prostate cancer cells.

Progression of castration-resistant tumors is frequent in prostate cancer. Current systemic treatments for castration-resistant prostate cancer only produce modest increases in survival time and self-renewing Tumor-Initiating Cells (TICs) are suspected to play an important role in resistance to these treatments. However it remains unclear whether the same TICs display both chemo-resistance and self-renewing abilities throughout progression from early stage lesions to late, castration resistant tumors. Here, we found that treatment of mice bearing LNCaP-derived xenograft tumors with cytotoxic (docetaxel) and anti-androgen (flutamide) compounds enriched for cells that express TROP2, a putative TIC marker. Consistent with a tumor-initiating role, TROP2high cells from androgen-sensitive prostate cancer cell lines displayed an enhanced ability to re-grow in culture following treatment with taxane-based chemotherapy with or without androgen blockade. TROP2 down-regulation in these cells reduced their ability to recur after treatment with docetaxel, in the presence or absence of flutamide. Accordingly, in silico analysis of published clinical data revealed that prostate cancer patients with poor prognosis exhibit significantly elevated TROP2 expression level compared to low-risk patients, particularly in the case of patients diagnosed with early stage tumors. In contrast, in androgen-independent prostate cancer cell lines, TROP2high cells did not exhibit a differential treatment response but were characterized by their high self-renewal ability. Based on these findings we propose that high TROP2 expression identifies distinct cell sub-populations in androgen-sensitive and androgen-independent prostate tumors and that it may be a predictive biomarker for prostate cancer treatment response in androgen-sensitive tumors.

The tumor-inhibitory effectiveness of a novel anti-Trop2 Fab conjugate in pancreatic cancer.

Human trophoblastic cell surface antigen 2 (Trop2) has been reported to act oncogenically. In this study, one-step quantitative real-time polymerase chain reaction (qPCR) test and immunohistochemistry (IHC) analysis with were employed to evaluate the relationship between Trop2 expression and the clinicopathological features of patients with PC. Then a novel anti-Trop2 Fab antibody was conjugated with Doxorubicin (DOX) to form Trop2Fab-DOX, an antibody-drug conjugate. This Trop2Fab-DOX conjugate was characterized by cell ELISA and immunofluorescence assay. MTT and wound healing analyses were used to evaluate the inhibitory effect of Trop2Fab-DOX on PC cell growth in vitro, while xenograft nude mice model was established to examine the tumor-inhibitory effects of PC in vivo. High Trop2 expression was observed in PC tissues and Trop2 expression was associated with several malignant attributes of PC patients, including overall survival. Trop2Fab-DOX can bind to the Trop2-expressing PC cells and provide an improved releasing type of DOX. In addition, Trop2Fab-DOX inhibited the proliferation and suppressed the migration of PC cells in a dose-dependent manner in vitro, while inhibited the growth of PC xenografts in vivo. Trop2 is a specific marker for PC, and a novel Trop2Fab-DOX ADC has a potent antitumor activity

TROP2 overexpression promotes proliferation and invasion of lung adenocarcinoma cells

Recent studies suggest that the human trophoblast cell-surface antigen TROP2 is highly expressed in a number of tumours and is correlated with poor prognosis. However, its role in non-small cell lung carcinoma (NSCLC) remains largely unknown. Here we examined TROP2 expression by immunohistochemistry in a series of 68 patients with adenocarcinoma (ADC). We found significantly elevated TROP2 expression in ADC tissues compared with normal lung tissues (P < 0.05), and TROP2 overexpression was significantly associated with TNM (tumour, node, metastasis) stage (P = 0.012), lymph node metastasis (P = 0.038), and histologic grade (P = 0.013). Kaplan–Meier survival analysis revealed that high TROP2 expression correlated with poor prognosis (P = 0.046). Multivariate analysis revealed that TROP2 expression was an independent prognostic marker for overall survival of ADC patients. Moreover, TROP2 overexpression enhanced cell proliferation, migration, and invasion in the NSCLC cell line A549, whereas knockdown of TROP2 induced apoptosis and impaired proliferation, migration, and invasion in the PC-9 cells. Altogether, our data suggest that TROP2 plays an important role in promoting ADC and may represent a novel prognostic biomarker and therapeutic target for the disease.

Trop2 is overexpressed in gastric cancer and predicts poor prognosis.

The cell surface protein Trop2 is overexpressed in a variety of human cancers. Trop2 expression increases tumor development and metastasis and reduces patient survival. However, little is known about the role of Trop2 expression and its prognostic value in gastric cancer (GC), particularly in Chinese populations. We analyzed Trop2 expression in GC tissues collected from Chinese GC patients. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry on tissue microarrays were performed to assess levels of Trop2 mRNA and protein in GC, and correlations between Trop2 expression and clinical characteristics and prognosis were analyzed. Trop2 expression was higher in GC tissues than in neighboring non-tumor tissues. Increased Trop2 protein levels in GC were associated with increased differentiation, tumor node metastasis stage, tumor size, lymph node metastasis, distant metastasis, and H. pylori infection. GC patients with high Trop2 expression also had poor overall survival rates. These data suggest Trop2 is a useful prognostic biomarker for GC.

Abstract P5-19-27: IMMU-132, a new antibody-drug conjugate (ADC) against Trop-2, as a novel therapeutic for patients with relapsed/refractory, metastatic, triple-negative breast cancer (TNBC): Results from Phase I/II clinical trial (NCT01631552)

Abstract Background: TNBC, comprising 15-20% of all invasive breast cancers, represents an aggressive phenotype with high risk of recurrence and mortality. Trop-2 is a cell-surface glycoprotein expressed on many human carcinomas, including TNBC. High Trop-2 expression is associated with more aggressive disease and poor prognosis in several cancers, including breast cancer. We report interim results from a Phase I/II trial evaluating a novel ADC, IMMU-132 (isactuzumab govitecan), comprising a humanized anti-Trop-2 antibody conjugated to the topoisomerase I inhibitor, SN-38 (active metabolite of irinotecan). The drug:antibody ratio of 7.6 facilitates the delivery of high-dose chemotherapy preferentially to the tumor cells. Methods: Patients (pts) with relapsed/refractory metastatic epithelial tumors were enrolled at escalating IMMU-132 doses (8 to 18 mg/kg), given on days 1 and 8 of a 21-day cycle. The Phase II dose at this schedule was 10 mg/kg. CT scans were performed every 6-8 weeks to assess response using RECIST 1.1. During the dose-escalation portion, evidence of antitumor activity, including 3 partial responses (TNBC, small-cell lung cancer and colorectal cancer) and many with durable stable disease (SD), was observed, leading to Phase II expansion. Results: As of Sept. 25, 2014, a total of 132 pts have been enrolled, including 30 with advanced/metastatic TNBC. Currently evaluable TNBC pts (N=17) had a median age of 50 (33-77), with a median of 4 prior drug regimens (range 1-8), and 67% having received prior platinum-containing regimens. In this heavily pre-treated population, there were 4 PRs (25%) and 9 SDs (56.3%) per RECIST v1.1, representing a disease control (PR+SD &amp;gt; 4 mos) of 53% among evaluable pts with adequate follow-up. A maximum shrinkage of target lesions of 33%, 44%, 51%, and 60% for pts with PRs, and 14%, 19%, and 27% for 3 pts with SD, was determined. Biomarker CA15.3 directional changes correlated with RECIST. All but one pathology specimen were Trop-2+ by immunohistochemistry. HPLC analysis of serum samples found &amp;lt;5% unbound SN-38. The half-life of IMMU-132 was 23 h, which is similar to the predicted half-life from in vitro serum stability studies. Grade 3/4 toxicities were: neutropenia (G3, 4 pts, 23.5%) with 1 febrile neutropenia (5.9%), and lymphocytopenia (1 Gr 3, 1 pt, 5.9%). Grade 1/2 events were fatigue (35.3%), diarrhea (41.2%), and alopecia (29.4%). No pt discontinued therapy due to toxicity. Conclusions: Based on laboratory and initial clinical results, IMMU-132 is an ADC that selectively delivers a topoisomerase I inhibitor to cancer cells without the need for enrichment by a companion diagnostic. It is safe, well-tolerated, with preliminary evidence of encouraging efficacy in heavily-pretreated pts with relapsed/refractory metastatic TNBC. Randomized Phase III and combination trials are being planned. Citation Format: Aditya Bardia, Alexander Starodub, Rebecca L Moroose, Ingrid A Mayer, Jennifer R Diamond, Ellen Chuang, Serengulam V Govindan, Robert M Sharkey, Pius Maliakal, William A Wegener, Steven A Hamburger, Allyson J Ocean, David M Goldenberg, Linda T Vahdat. IMMU-132, a new antibody-drug conjugate (ADC) against Trop-2, as a novel therapeutic for patients with relapsed/refractory, metastatic, triple-negative breast cancer (TNBC): Results from Phase I/II clinical trial (NCT01631552) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-19-27.

Prognostic value of TROP2 expression in patients with gallbladder cancer.

Altered expression of TROP2 is observed in various types of human cancers. However, the clinical significance and pathological role of TROP2 in gallbladder cancer (GBC) remains unclear. The main objective of this investigation was to clarify the relationships between TROP2 expression and the clinicopathological features of patients with GBC. Immunohistochemistry was performed to investigate the expression of TROP2 and epithelial-mesenchymal transition (EMT) indicator proteins in 93 patients with GBC. Immunohistochemistry showed that the protein expression level of TROP2 was significantly higher in GBC tissues than in adjacent noncancerous tissues. In addition, immunohistochemistry analysis showed that TROP2 expression was significantly correlated with histologic grade (P=0.038), tumor stage (P=0.015), and lymph node metastasis (P=0.007). Furthermore, high TROP2 expression was significantly associated with a loss of the epithelial marker E-cadherin (P=0.013) and acquisition of expression of the mesenchymal marker vimentin (P=0.031). Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between TROP2 expression and prognosis of GBC patients. Kaplan-Meier analysis indicated that patients with high TROP2 expression had poor overall survival (P<0.001). Multivariate analysis showed that high TROP2 expression was an independent predictor of overall survival. In conclusion, our data suggest for the first time that the increased expression of TROP2 in GBC is associated significantly with aggressive progression and poor prognosis. In conclusion, this study confirmed that TROP2 might be involved in regulating the EMT and malignant progression in GBC. It also provided the first evidence that TROP2 expression in GBC was an independent prognostic factor of patients, which might be a potential diagnostic and therapeutic target of GBC.

Trop-2-targeting tetrakis-ranpirnase has potent antitumor activity against triple-negative breast cancer

BackgroundRanpirnase (Rap) is an amphibian ribonuclease with reported antitumor activity, minimal toxicity, and negligible immunogenicity in clinical studies, but the unfavorable pharmacokinetics and suboptimal efficacy hampered its further clinical development. To improve the potential of Rap-based therapeutics, we have used the DOCK-AND-LOCK™ (DNL™) method to construct a class of novel IgG-Rap immunoRNases. In the present study, a pair of these constructs, (Rap)2-E1-(Rap)2 and (Rap)2-E1*-(Rap)2, comprising four copies of Rap linked to the CH3 and CK termini of hRS7 (humanized anti-Trop-2), respectively, were evaluated as potential therapeutics for triple-negative breast cancer (TNBC).MethodsThe DNL-based immunoRNases, (Rap)2-E1-(Rap)2 and (Rap)2-E1*-(Rap)2, were characterized and tested for biological activities in vitro on a panel of breast cancer cell lines and in vivo in a MDA-MB-468 xenograft model.Results(Rap)2-E1-(Rap)2 was highly purified (>95%), exhibited specific cell binding and rapid internalization in MDA-MB-468, a Trop-2-expressing TNBC line, and displayed potent in vitro cytotoxicity (EC50 ≤ 1 nM) against diverse breast cancer cell lines with moderate to high expression of Trop-2, including MDA-MB-468, BT-20, HCC1806, SKBR-3, and MCF-7. In comparison, structural counterparts of (Rap)2-E1-(Rap)2, generated by substituting hRS7 with selective non-Trop-2-binding antibodies, such as epratuzumab (anti-CD22), were at least 50-fold less potent than (Rap)2-E1-(Rap)2 in MDA-MB-468 and BT-20 cells, both lacking the expression of the cognate antigen. Moreover, (Rap)2-E1-(Rap)2 was less effective (EC50 > 50 nM) in MDA-MB-231 (low Trop-2) or HCC1395 (no Trop-2), and did not show any toxicity to human peripheral blood mononuclear cells. In a mouse TNBC model, a significant survival benefit was achieved with (Rap)2-E1*-(Rap)2 when given the maximal tolerated dose.ConclusionsA new class of immunoRNases was generated with enhanced potency for targeted therapy of cancer. The promising results from (Rap)2-E1-(Rap)2 and (Rap)2-E1*-(Rap)2 support their further investigation as a potential treatment option for TNBC and other Trop-2-expressing cancers.

Increased expression of Trop2 correlates with poor survival in extranodal NK/T cell lymphoma, nasal type

Human trophoblastic cell surface antigen 2 (Trop2) has been suggested to play an important role in the development of solid tumors. However, the expression of Trop2 in extranodal NK/T cell lymphoma, nasal type (ENKTL) and the relationship with the clinical characteristics of this disease remain poorly understood. In this study, one-step quantitative PCR reverse transcription-polymerase chain reaction and immunohistochemical staining with tissue sections were employed to evaluate the expression of Trop2 in ENKTL. Furthermore, the relationship between Trop2 expression and prognosis of ENKTL was investigated. Expression of Trop2 mRNA and protein was significantly higher in ENKTL tissue than in corresponding non-lymphomatous tissue (p = 0.04 and p < 0.001, respectively). Expression of Trop2 protein in ENKTL was associated with lymph node involvement and poor overall survival (p = 0.045 and p = 0.018, respectively). Kaplan-Meier analysis and the logrank test indicated that lymph node involvement (p = 0.0481), single therapy strategy (p = 0.0037), and high expression of Trop2 (p = 0.0042) are significantly correlated with poor prognosis of ENKTL patients. The data suggest that Trop2 expression reflects a more malignant phenotype and may serve as an unfavorable prognostic factor for ENKTL.

TROP2 Correlates with Microvessel Density and Poor Prognosis in Hilar Cholangiocarcinoma

BackgroundTrophoblast cell surface antigen 2 (TROP2) was found to be associated with tumor progression and poor prognosis in a variety of epithelial carcinomas. The aim of the study was to investigate TROP2 expression and its prognostic impact in hilar cholangiocarcinoma. MethodsImmunohistochemistry and quantitative real-time PCR were used to determine TROP2 expression in surgical specimens from 70 hilar cholangiocarcinoma patients receiving radical resection. The relationship between TROP2 expression and microvessel density was investigated and standard statistical analysis was used to evaluate TROP2 prognosis significance in hilar cholangiocarcinoma. ResultsHigh TROP2 expression by immunohistochemistry was found in 43 (61.4 %) of the 70 tumor specimens. Quantitative real-time PCR confirmed that TROP2 level in tumor was significantly higher than in non-tumoral biliary tissues (P = 0.001). Significant correlations were found between TROP2 expression and histological differentiation (P = 0.016) and tumor T stage (P = 0.031) in hilar cholangiocarcinoma. TROP2 expression correlated with microvessel density in hilar cholangiocarcinoma (P = 0.026). High TROP2 expression patients had a significantly poorer overall survival rate than those with low TROP2 expression (30 vs. 68.5 %, P = 0.001), and multivariate Cox regression analysis indicated TROP2 as an independent prognostic factor for hilar cholangiocarcinoma (P = 0.004). ConclusionTROP2 expression correlates with microvessel density significantly and is an independent prognostic factor in human hilar cholangiocarcinoma.

TROP2 expression and its evolving role in tumor pathogenesis in systemic tumors

To the Editor: I read with great interest the recent article by Fang et al. [1]. TROP2 may play a major role in tumor pathogenesis in a number of systemic malignancies. Pulmonary squamous cell carcinomas tend to show increased expression of TROP2. A close association exists between the pathological T stage and TROP2 overexpression in pulmonary squamous cell carcinomas [2]. Poorly differentiated lung tumors tend to exhibit increased expression of TROP2. TROP2 also influences and alters IGF-1R signaling in these tumors [3]. Patients with pulmonary adenocarcinomas, especially those in stage II or III that overexpressTROP2, tend to have a better clinical outcome. They also exhibit better survival rates. Thus, TROP2 overexpression is an important independent marker of prognosis in lung carcinomas. A similar relationship is seen in colorectal carcinomas [4]. Decreased overall survival and increased invasiveness is seen in stage IIB colorectal carcinomas that show upregulation of TROP2. Interestingly, there is differential expression of TROP2 and tumor aggressiveness in between rightand left-sided colorectal carcinomas [5]. For instance, left-sided colorectal carcinomas show significantly higher TROP2 expression in contrast to TROP2 expression in right-sided colon carcinomas. Recent data suggest that TROP2 is an independent parameter influencing prognosis in left-sided colon carcinomas. Tumors with accentuated TROP2 expression also demonstrate more lymph node metastases as well as deeper depth of invasion. In patients with left-sided squamous cell carcinoma and low TROP2 expression, the median survival time is 63.1months in contrast to 45.9months in those with high TROP2 expression [5–7]. TROP2 expression is also an important parameter that influences the risk of developing hepatic metastasis. About 56 % of gastric malignancies, especially the intestinal type, exhibit TROP2 overexpression [8]. Assessment of TROP2 in intestinal type gastric malignancies is highly significant. In these tumors, TROP2 is an independent parameter that influences cancer recurrence. In lymph nodepositive patients, a negative relationship exists between TROP2 overexpression and disease-free survival as well as overall survival. It promotes cancerogenesis by activating the ERK MAPK pathway [9]. Fifty-five percent of pancreatic malignancies exhibit TROP2 overexpression [10]. In pancreatic malignancies that demonstrate accentuated levels of TROP2, a poor clinical outcome is seen typically. A positive relationship exists between lymph node metastasis and TROP2 overexpression. Similarly, a positive relationship exists between tumor grade and TROP2 overexpression. In the end, TROP2 overexpression is associated with decreased progression-free survival as well as decreased overall survival. The above examples clearly illustrate the role of TROP2 in systemic carcinogenesis and the need for further studies in this regard.

Different effects of ERβ and TROP2 expression in Chinese patients with early-stage colon cancer

Estrogen receptor beta (ERβ) and TROP2 expressed in colon carcinoma and might play an important role there. We explored the relationship of ERβ and TROP2 expression with the prognosis of early-stage colon cancer. ERβ and TROP2 levels were assessed by immunohistochemistry in normal mucosa and tumoral tissues from 220 Chinese patients with T(3)N(0)M(0) (stage IIa) and T(4)N(0)M(0) (stage IIb) colon cancer in the Cancer Center, Sun Yat-sen University, who underwent curative surgical resection between 1995 and 2003. The Cox proportional hazards regression model was applied to analyze the overall survival (OS) data, and the ROC curve, Kaplan-Meier estimate, log rank test, and Jackknife method were used to show the effect of ERβ and TROP2 expression at different stages of cancer. The 5-year survival rates were not significantly different between the patients with stage IIa and stage IIb colon cancer (83 vs. 80 %, respectively). The high expression of ERβ was related to decreasing OS in stage IIa and stage IIb colon cancer, while the high expression of TROP2 was related to decreasing OS in stage IIb colon cancer. The expression of ERβ and TROP2 has tumor-suppressive and tumor-promoting effect in stage IIa and stage IIb colon cancer, respectively.

Trop-2 Overexpression in Poorly Differentiated Endometrial Endometrioid Carcinoma: Implications for Immunotherapy With hRS7, a Humanized Anti–Trop-2 Monoclonal Antibody

We evaluated the expression of human trophoblast cell surface marker (Trop-2) in endometrial endometrioid carcinoma (EEC) and the potential application of hRS7, a humanized monoclonal anti-Trop-2 antibody, as a therapeutic agent against poorly differentiated EEC. Trop-2 expression was evaluated by immunohistochemistry in 131 EEC with different degrees of differentiation and 32 normal endometrial controls (NEC). Trop-2 expression was also evaluated by quantitative real-time polymerase chain reaction and flow cytometry in 3 primary EEC cell lines derived from patients harboring poorly differentiated EEC. Finally, the sensitivity of grade 3 EEC cell lines to hRS7 antibody-dependent cellular cytotoxicity was tested in standard 5-hour Cr release assays. Trop-2 expression was detected in 126 (96.2%) of 131 EEC samples. Tumor tissues showed markedly increased Trop-2 positivity compared with NEC (P = 0.001). Trop-2 expression was significantly higher in all grades of EEC versus NEC. Grade 3 tumors displayed significantly stronger Trop-2 immunostaining compared with grade 1 EEC (P = 0.01). High Trop-2 expression by quantitative real-time polymerase chain reaction and flow cytometry was found in 1 grade 3 EEC primary cell line (EEC-ARK-1). Unlike Trop-2-negative EEC cell lines, EEC-ARK-1 was found highly sensitive to hRS7-mediated antibody-dependent cellular cytotoxicity in vitro (range of killing, 33.9%-50.6%; P = 0.004). Human serum did not significantly inhibit hRS7-mediated cytotoxicity against EEC-ARK-1 (P = 0.773). Trop-2 is highly expressed in EEC, and its expression is significantly higher in poorly differentiated EEC when compared with well-differentiated EEC. Primary grade 3 EECs overexpressing Trop-2 are highly sensitive to hRS7-mediated cytotoxicity in vitro. hRS7 may represent a novel therapeutic agent for the treatment of high-grade EEC refractory to standard treatment modalities.