TROP2 antibody drug conjugates (ADCs) are under active development. We seek to determine whether we can enhance activity of TROP2 ADCs by increasing TROP2 expression. In metaplastic breast cancers (MpBC), there is limited expression of TROP2, and downregulating transcription factor ZEB1 upregulates E-cad and TROP2, thus sensitizing cancers to TROP2 ADC sacituzumab govitecan (SG). Demethylating agent decitabine decreases DNA methyltransferase expression and TROP2 promoter methylation and subsequently increases TROP2 expression. Decitabine treatment as well as overexpression of TROP2 significantly enhance SG antitumor activity. Decitabine also increases SLFN11, a biomarker of topoisomerase 1 inhibitor (TOP1) sensitivity and is synergistic with SG which has a TOP1 payload, in TROP2-expressing SLFN11-low BC cells. In conclusion, TROP2 and SLFN11 expression can be epigenetically modulated and the combination of demethylating agent decitabine with TROP2 ADCs may represent a novel therapeutic approach for tumors with low TROP2 or SLFN11 expression.
Purpose: TROP2 is overexpressed in many tumor types and is being actively pursued as a target. Sacituzumab govitecan (SG), a humanized anti-TROP2 antibody conjugated with SN-38, was approved for treatment of metastatic triple negative breast cancer, with the greatest efficacy in patients with medium or high TROP2 levels. We sought to enhance efficacy of TROP2-targeted therapies by pharmacological regulation of TROP2 expression. Methods: TROP2 levels were assessed by immunohistochemistry (IHC) in two sets of breast tumors: a set of surgical samples and a tissue microarray. TROP2 mRNA expression was assessed in surgical samples and breast cancer patient-derived xenografts (PDXs) with RNAseq and assessed in the TCGA. In cell lines, expression of TROP2, E-cadherin (E-cad), and Schlafen family member 11 (SLFN11) were assessed by immunoblotting and qPCR following drug treatment or cell line manipulation. Epithelial-mesenchymal transition was evaluated by cell migration, cell invasion, and anchorage-independent growth assays. Antitumor efficacy of drug combination was assessed by cell survival, cell colony formation, and apoptosis assays. Results: By IHC, TROP2 was expressed in only 40% of metaplastic breast cancers (MpBC), but nearly all non-MpBC tumors. TCGA database evaluation further showed higher TROP2 levels in non-MpBC tumors than metaplastic tumors. In breast cancer surgical specimens, breast cancer PDXs, and the TCGA, there was a strong correlation between TROP2 and E-cad expression. In vitro, we demonstrated that downregulating transcriptional factor zinc finger E-box binding homeobox 1 (ZEB1) led to mesenchymal-epithelial transition with upregulation of both E-cad and TROP2 expression in breast cancer cells, leading to increased sensitivity to SG treatment. Screening of epigenetic modulators identified DNA methyltransferase inhibitor decitabine as an enhancer of TROP2 and E-cad expression in PDX cell lines of metaplastic cancer origin and mesenchymal subtype breast cancer cell lines. Decitabine increased TROP2 expression by decreasing TROP2 promoter methylation. Decitabine was significantly synergistic with SG, and enhanced apoptosis. Similarly, overexpression of TROP2 (by plasmid) in cell lines enhanced activity of SG. Furthermore, decitabine increased expression of SLFN11, a putative biomarker of SN38 sensitivity, and was synergistic with SG in TROP2 expressing, SLFN11 low breast cancer cell lines. Conclusion: TROP2 is expressed in most breast cancers, but is expressed less frequently in MpBC, an aggressive subtype unresponsive to traditional therapies. Epigenetic modulator decitabine upregulates TROP2 and SLFN11 expression and enhances antitumor efficacy of SG. Combinatorial treatment of TROP2 ADCs with epigenetic modulators of TROP2 represent a novel therapeutic strategy for tumors with low TROP2 or SLFN11 expression. Citation Format: Ming Zhao, Timothy P. DiPeri, Gabriela Raso, Yasmeen Q. Rizvi, Xiaofeng Zheng, Kurt Evans, Argun Akcakanat, Fei Yang, Debu Tripathy, Ecaterina Ileana Dumbrava, Senthil Damodaran, Funda Meric-Bernstam. Epigenetically upregulating TROP2 enhances therapeutic efficacy of TROP2 ADC sacitizumab govitecan [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 1791.
Purpose: Genomic aberrations in fibroblast growth factor receptor (FGFR) are oncogenic drivers in several cancers. FGFR inhibitors (FGFRi) have demonstrated antitumor activity in cholangiocarcinoma (CCA) with FGFR2 fusions/rearrangements, though acquired resistance remains a therapeutic challenge and has been linked to FGFR2 mutations other than fusions/rearrangements. We sought to investigate mechanisms of acquired resistance to FGFRi and approaches to overcome resistance. Methods: Longitudinal plasma samples were collected from patients with FGFR pathway alterations enrolled in the futibatinib phase I trial (NCT02052778) and sequenced using a targeted, 73-gene panel. A separate retrospective analysis was conducted to evaluate possible evolution of genomic aberrations in CCA patients with FGFR2 fusion/rearrangement who had additional tumor and/or plasma next-generation sequencing (NGS) following FGFRi therapy. To assess the efficacy of futibatinib in cells with FGFR2 fusions in vitro, a FGFR2-BICC1 fusion H69 cholangiocyte cell line was developed. MAPK pathway alterations (BRAF_V600E or KRAS_G12D) were introduced to determine the impact of these co-alterations on FGFRi sensitivity, and combinations were tested to determine if efficacy could be enhanced. Cell viability assays, colony formation assays, and western blots were utilized to determine the effects of these agents in engineered cells. Results: A total of 58 plasma samples were collected from 17 patients with FGFR pathway alterations who were enrolled in the futibatinib phase I trial, including 13 (76.5%) of which had CCA. One patient with a FGFR2-CTNNA3 fusion who had NRAS G12D and BRAF A694T at baseline which were undetected during treatment had a dramatic increase in their variant allele frequency (VAF) upon progression (4.2%-0.0%-100% and 2.8%-0.0%-50.9%, respectively). Further, additional MAPK alterations were detected at time of progression, including BRAF V600E, NRAS Q61K, NRAS G12C, NRAS G13D and KRAS G12K mutations. In our separate retrospective series, of 17 patients who underwent repeat tumor and/or plasma NGS following treatment with one or more FGFRi, 10 (58.8%) had newly detectable alterations in MAPK pathway genes, 10 (58.8%) had new FGFR2 alterations, and 7 (41.2%) developed new alterations in both FGFR2 and MAPK pathway genes. In vitro studies demonstrated that in isogenic H69 biliary cell lines, introduction of FGFR2-BICC1 robustly sensitized to FGFRi when compared to a parental cell line, which was blunted by the introduction of secondary KRAS_G12D or BRAF_V600E mutations. Conclusions: Convergent genomic evolution in the MAPK pathway may be a potential mechanism of acquired resistance to FGFRi therapy. Work is ongoing to determine if targeting co-alterations may enhance the efficacy of FGFRi in FGFR2-fusion driven malignancies. Citation Format: TImothy P. DiPeri, Ming Zhao, Tyler Moss, Michael Kahle, Payal Rauli, Sunyoung S. Lee, Abdel Halim, Hiroshi Hirai, Volker Wacheck, Karim Benhadji, Jordi Rodon, Milind Javle, Funda Meric-Bernstam. Convergent MAPK pathway alterations mediate acquired resistance to FGFR inhibitors in cholangiocarcinoma with FGFR fusions/rearrangements [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 2618.
Purpose: Several FGFR alterations have been found in breast cancer, however, their role as a therapeutic target in breast has been controversial. Futibatinib (TAS-120; Taiho) is a novel, selective pan-FGFR inhibitor which irreversibly binds to and inhibits FGFR1-4 at nanomolar concentrations. We sought to determine the efficacy of futibatinib in breast cancer models with differing FGFR alterations. Experimental Design: In vivo, antitumor efficacy was evaluated by tumor growth curves and event-free survival in a panel of patient-derived xenografts (PDXs) from breast cancer patients with different FGFR1-4 alterations. Genomic alterations in the PDXs were characterized by next generation sequencing. Correlation of FGFR gene expression in matched patient tumors and PDXs was analyzed by RNA sequencing. In vitro, FGFR2 Y375C mutant and FGFR2-BICC1 fusion expressing MCF10A cell lines were generated, and effect on cell proliferation, colony formation assay, and cell signaling was assessed with and without futibatinib. Frequency of FGFR mutations and FGFR2 amplification was compiled from internal and public databases. Results: Breast cancer PDXs varied in their expression of FGFR1-4. FGFR gene expression significantly correlated between matched patient tumors and PDXs derived from them, however, PDXs had higher levels of FGFR3 and FGFR4 expression compared to patient samples. Futibatinib inhibited tumor growth in three of 10 PDX models, with tumor stabilization in a FGFR2 amplified model and prolonged tumor regression (more than 110 days) in a PDX bearing a FGFR2 Y375C mutation. In vitro, expression of FGFR2 Y375C, as well as FGFR2-BICC fusion in normal-like MCF10A cells enhanced growth, colony formation ability and FGFR signaling. Cells expressing FGFR2 Y375C as well as FGFR2-BICC fusions were more sensitive to futibatinib. In the five breast cancer genomic series we analyzed, FGFR2 mutations and amplifications were found in 1.1%-2.6% and 1.4%-2.5%, respectively. Conclusions: Futibatinib had single agent activity of selected breast cancer PDX models. FGFR2 activating mutations and amplification may represent rare but promising therapeutic targets to FGFR inhibition. Citation Format: Turcin Saridogan, Argun Akcakanat, Ming Zhao, Kurt W. Evans, Erkan Yuca, Stephen Scott, Bryce P. Kirby, Xiaofeng Zheng, Senthil Damodaran, Funda Meric-Bernstam. Efficacy of futibatinib, an irreversible fibroblast growth factor receptor (FGFR) inhibitor, in breast cancer models with FGFR alterations [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-08-12.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.