bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1214: Identification of URST1 as a prognostic biomarker and therapeutic target for lung cancer
Authors: Takano Atsushi , Miyagi Yohei , Daigo Yataro
Published: July 2021

This study aims to identify novel biomarkers and therapeutic targets for lung cancer. Our strategies are as follows: i) Identification of up-regulated genes in lung cancers by gene expression profile analysis, ii) Validation of clinicopathological importance of their protein expression using tissue microarray, iii) Examination of their effect on cancer cell proliferation/survival by siRNAs and/or small molecules. During this process, we identified up-regulated in solid tumor 1 (URST1). Immunohistochemical analysis of URST1 expression revealed that URST1 expression was observed in the majority of non-small cell lung cancers (NSCLCs) and SCLCs. Strong positivity of URST1 staining was correlated with tumor size and lymph node metastasis and it was significantly associated with poor prognosis for NSCLC patients. Multivariate analysis showed that strong expression of URST1 was an independent prognostic factor for NSCLCs that had undergone curative surgery. Inhibition of URST1 expression by siRNAs for URST1 suppressed the growth and invasive ability of lung cancer cells. Treatment of lung cancer cells with selective inhibitors for URST1 significantly suppressed the cell growth partly through G2/M arrest and subsequent cell death. Downstream targets of URST1 were identified by microarray analysis using lung cancer cells transfected with siRNAs for URST1. Targeting URST1 is likely to be an effective diagnostic and therapeutic approach for lung cancer.

Citation Format: Atsushi Takano, Yohei Miyagi, Yataro Daigo. Identification of URST1 as a prognostic biomarker and therapeutic target for lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1214.
Abstract 1244: Discovery of a novel anticancer benzopyrane derivative with an effective multitarget mechanism of action
Authors: Zaher Dana , Ramadan Wafaa , El-Awady Raafat , Omar Hany , Hersi Fatema , Srinivasulu Vunnam , Al-Tel Taleb
Published: July 2021

Introduction: Cancer is a leading cause of death worldwide, as about 1 in 6 deaths is due to cancer. Despite the advances in cancer treatment, the success rate of cancer cure is very low, due to the low therapeutic index and many off target side effects of the available anticancer drugs. This highlight the urgent need for the development of novel anticancer compounds with high efficacy and wide safety margin.

Methods: Phenotypic screening of a skeletally diverse library of benzopyrane yielded a unique chemotype with novel anticancer mechanism. Cell viability assays were performed against a panel of cancer cell lines followed by various assays to verify the effect of our compound on inducing apoptosis, DNA damage, cell cycle arrest. For further explore the compound's mechanism of action, a proteomic study was conducted along with western blot analysis, metabolism studies and other enzymes specific mechanistic assays. In addition, mouse tumor model was developed to assess the safety and the activity of the compound in vivo.

Results: The novel compound possesses a potent anticancer effect against multiple cancer cell lines, induces apoptosis, DNA damage and perturbs the cell cycle progression. Interestingly, it inhibits the activity of essential enzymes involved in the cell's redox balance including Thioredoxin and Glutathione reductases. Moreover, it inactivates vital cancer survival pathways. Lastly, the compound safely reduces tumor proliferation in vivo.

Conclusion: Due to the achieved safety profile, potency and efficacy of this novel benzopyrane derived agent as well as its unique mechanism of action, the compound is a potential candidate for further testing in preclinical and clinical settings.

Keywords: Multitarget, apoptosis, DNA damage, cell cycle, thioredoxin reductase, glutathione reductase

Citation Format: Dana Zaher, Wafaa Ramadan, Raafat El-Awady, Hany Omar, Fatema Hersi, Vunnam Srinivasulu, Taleb Al-Tel. Discovery of a novel anticancer benzopyrane derivative with an effective multitarget mechanism of action [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1244.
Abstract 1251: Dithiocarb-copper complex, CuET, demonstrates anti-neoplastic activity in mouse model of prostate cancer and prevents recurrence of tumors
Authors: Dumut Daciana Catalina , DeSanctis Juan B. , Mistrik Martin , Skrott Zdenek , Dzubak Petr , Bartek Jiri , Hajduch Marian , Radzioch Danuta
Published: July 2021

INTRODUCTION Prostate cancer (PCa) is the most common cancer in the North-American man. It was responsible for about 192,000 new cases and 33,000 deaths in the USA in 2020. Surgical resection and systemic androgen deprivation therapy are standard approaches to treat both localized and metastatic PCa (mPCa). The five-year survival from prostate cancer (PCa) without bone metastasis is 56% versus 3% with metastasis There is no cure for the metastatic prostate cancer (mPCa) which often spreads to the hip, spine, and pelvis bones. Therefore, new approaches and combination therapy need to be developed to improve patients's survival. Disulfiram's anti-cancer activity was previously explored and its metabolite ditiocarb-copper complex (CuET) was found to have high anti-cancer activity. The mechanism of action of CuET involves NPL4 aggregation and activation of ER stress, leading to preferential apoptosis of cancer cells. Since altered protein degradation is targeted by CuET, it might display high efficacy in highly mutated PCa. Consequently, we want to propose CuET for the treatment of mPCa.

METHODS Survival curve and colony-formation assays in murine dKO cell line harboring PTEN and Rb driver mutations as well as in the human metastatic PC3 cell line, were performed. Anti-metastatic effect of CuET in vitro was assessed through Boyden chamber. In vivo efficacy of systemic treatment with CuET, was studied in dKO model of C57BL/6 mice.

RESULTS Our results demonstrate that CuET displays cytotoxicity in dKO and PC3 cells at very low concentrations with respective IC50 of 46.2nM and 90.5nM. In vitro, CuET significantly reduced both the clonogenicity and migration ability of cells. In vivo, systemic treatment with CuET significantly reduced growth of dKO tumor and prevented recurrence of tumors.

CONCLUSION Given these positive pre-clinical results, CuET should be investigated for its antineoplastic activity in clinical setting as an adjuvant therapy for mPCa.

Citation Format: Daciana Catalina Dumut, Juan B. DeSanctis, Martin Mistrik, Zdenek Skrott, Petr Dzubak, Jiri Bartek, Marian Hajduch, Danuta Radzioch. Dithiocarb-copper complex, CuET, demonstrates anti-neoplastic activity in mouse model of prostate cancer and prevents recurrence of tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1251.
Abstract 1279: Development of a selective CDK2-E inhibitor in CCNE driven cancers
Authors: Choi Yoon J. , Wenglowsky Steve , Brown Victoria , Bifulco Neil , Choi Yeon S. , Guo Jian , Hatlen Megan , Kim Joseph , LaBranche Tim , Lobbardi Riadh , Perola Emanuele , Rozsahegyi Emily , Maynard Michelle , Ramsden Phil , Silva Grace , Stevison Faith , Vargas Richard , Wang Ruduan , Wilson Doug , Woessner Rich , Zhang Dean , Meissner Rob , Hoeflich Klaus , Dorsch Marion
Published: July 2021

Background: Cyclin dependent kinases (CDK) comprise a family of proteins which are activated upon cyclin binding to promote cell cycle progression. Historically, CDK family inhibitors have had limited utility in the clinic due to 1) toxicities associated with broad spectrum CDK inhibition; and 2) varied and unpredictable efficacy due to lack of a patient selection strategy. The recent approval of three selective CDK4/6 drugs (palbociclib, ribociclib and abemaciclib) has revived the pursuit of therapies against a related interphase kinase, CDK2. Cyclin E gene (CCNE) alterations are prevalent in cancers with high unmet medical need and are emerging as a potential mechanism of clinical resistance to targeted therapies (e.g. CDK4/6 therapies).

Methods: Here we report preclinical validation leading to the development of a selective CDK2 inhibitor for the treatment of cancers harboring CCNE alterations. We highlight advanced, orally bioavailable compounds exhibiting single-digit low nanomolar biochemical and cellular potency (pRB), exquisite CDK family selectivity (CDK1, 4, 6, 7 and 9), and whole kinome selectivity. We have characterized the phenotypic and mechanistic consequences of targeting CDK2, employing both genetic and pharmacologic methods across cell lines and xenograft models (e.g. OVCAR-3, MKN-1, HCC1569).

Results: In a panel of cell lines, CCNE1-amplified lines exhibited profound sensitivity to selective CDK2 inhibition by halting cells at the G1/S phase of the cell cycle. Upon further inspection, CDK2 inhibition induced multiple markers of senescence, e.g. SA-b-gal and IL-6, in CCNE1-amplified but not in CCNE non-amplified cell lines. Consistent with this, these compounds exhibit robust anti-tumor activity in multiple CCNE1-amplified xenograft models, which was sustained after removal of treatment with these compounds.

Conclusions: These data provide a strong rationale for advancing this class of compounds toward clinical development in CCNE-altered cancers.

Citation Format: Yoon J. Choi, Steve Wenglowsky, Victoria Brown, Neil Bifulco, Yeon S. Choi, Jian Guo, Megan Hatlen, Joseph Kim, Tim LaBranche, Riadh Lobbardi, Emanuele Perola, Emily Rozsahegyi, Michelle Maynard, Phil Ramsden, Grace Silva, Faith Stevison, Richard Vargas, Ruduan Wang, Doug Wilson, Rich Woessner, Dean Zhang, Rob Meissner, Klaus Hoeflich, Marion Dorsch. Development of a selective CDK2-E inhibitor in CCNE driven cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1279.
Abstract 1394: Poly ADP-ribose polymerase inhibitor promotes the immunoradiotherapeutical efficacy in small cell lung cancer
Authors: Zhang Nannan , Gao Yanping , Zeng Zihang , Luo Yuan , Jiang Xueping , Zhang Jianguo , Li Jiali , Huang Zhengrong , Gong Yan , Xie Conghua
Published: July 2021

This study aimed to investigate the safety and efficacy of radiotherapy combined with poly ADP-ribose polymerase (PARP) inhibitors and immune checkpoint inhibitors in small cell lung cancer (SCLC). Tumor-bearing xenograft mouse model was used to examine the safety and anti-tumor effects of radiotherapy plus niraparib and PD-1 antibodies. SCLC cell lines were used to explore the underlying mechanisms in this combination. PARP inhibitor suppressed SCLC cell proliferation, induced cell apoptosis, and increased cell cycle arrest at G2/M phase. Niraparib treatment augmented radiation-induced double-strand DNA breaks, which subsequently activated the cGAS/STING pathway to increase the expression levels of CXCL10, CCL5 and PD-L1 in SCLC cells. Moreover, the combination of radiation, niraparib and PD-1 antibodies significantly inhibited SCLC tumor growth and prolonged the survival of immunocompetent C57BL/6 mice. The induced CCL5 and CXCL10 activated CD8+ T cells in vivo. Our study indicated that niraparib combined with radiation promoted immune checkpoint inhibitor functions via inducing PD-L1 expression, and activated CD8+ T cells via increasing CXCL10 and CCL5 levels through cGAS/STING pathway. The combination treatment of PARP inhibitors, radiotherapy and immunotherapy were safe in vivo, effectively suppressed SCLC tumor progression, increased survival and decreased the adverse events via lowering the dose of individual treatment.

Citation Format: Nannan Zhang, Yanping Gao, Zihang Zeng, Yuan Luo, Xueping Jiang, Jianguo Zhang, Jiali Li, Zhengrong Huang, Yan Gong, Conghua Xie. Poly ADP-ribose polymerase inhibitor promotes the immunoradiotherapeutical efficacy in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1394.
Abstract 1451: AN3025: A novel anti-human TNFR2 antibody that exhibits immune activation and strong anti-tumor activity in vivo
Authors: Chen Yonglin , Jia Manxue , Xu Sherry , Zhao Yanhui , Chan Eric , Zhang Meng , Chen Emma , Zhang Yi
Published: July 2021

Background:

The unique biology and expression pattern of tumor necrosis factor receptor-2 (TNFR2) make it an attractive therapeutic target for immuno-oncology. TNFR2 highly expresses on a subset of regulatory T cells (Tregs) and MDSCs within tumor microenvironment that can activate these cells through nuclear factor kappa B (NF-kB) pathway. TNFR2+ Treg has been shown to be most suppressive among all Treg populations in tumor. On the other hand, TNFR2 is also abundantly expressed on the surface of many human tumors. TNFR2 blocking antibody is expected to relieve TNFR2-mediated immunosuppression and inhibit TNFR2-expressing tumor cell survival. AN3025 is a novel humanized IgG1 (variant) anti-hTNFR2 antibody under preclinical development. The immunomodulatory and anti-tumor activity of AN3025 were evaluated both in vitro and in vivo.

Materials and methods:

AN3025 was generated through rabbit immunization followed by phage display, then humanized by CDRs grafting. The binding affinity and specificity were studied by ELISA and FACS. The ability of AN3025 to mitigate TNF/TNFR2 signaling pathway was characterized using TNFR2 overexpressing Jurkat cell line in vitro. The in vivo anti-tumor activity was evaluated in TNFR2 humanized mouse model bearing MC38 tumor. The tumor samples from control and AN3025 treated mice were taken for further FACS and RNA seq analysis.

Results:

AN3025 binds to the extracellular domain of human TNFR2 with sub-nanomolar affinity and specificity. It cross-reacts with cynomolgus TNFR2 with similar affinity, but not with mouse or rat TNFR2. Mechanistically, AN3025 partially competes with TNFα for binding to TNFR2 receptor and inhibits TNFα induced hTNFR2 overexpressing Jurkat cell death, however it lacks of agonist activity towards TNFR2 even in the presence of hFC crosslinking. In vivo AN3025 significantly inhibits MC38 tumor growth as a monotherapy in hTNFR2 mouse model, while no impact on body weight. Subsequent FACS analysis suggests decreased Tregs% in AN3025 treated tumor. RNA seq suggests immune activation such as increased IFN-gamma and Granzyme expression. In addition, AN3025 enhances anti-tumor efficacy of mPD-1 antibody in a combination study.

Conclusions:

AN3025 is a novel anti-hTNFR2 antibody and demonstrates immunomodulatory activity and potent anti-tumor efficacy in vivo, supporting its clinical development for the treatment of human cancers.

Citation Format: Yonglin Chen, Manxue Jia, Sherry Xu, Yanhui Zhao, Eric Chan, Meng Zhang, Emma Chen, Yi Zhang. AN3025: A novel anti-human TNFR2 antibody that exhibits immune activation and strong anti-tumor activity in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1451.
Abstract 1461: PHI-101, a potent and novel inhibitor of CHK2 in ovarian and breast cancer cells
Authors: Han June H-J , Kim Kyu-Tae , Im Jeejin , Park Sojung , Choi Min Kyung , Kim Inki , Nam Ky-Youb , Yoon JeongHyeok
Published: July 2021

Purpose: Development of the potent and selective checkpoint kinase 2 (CHK2) inhibitor to overcome limiting clinical utility of poly(ADP-ribose) polymerase 1 (PARP1) inhibitors.

Experimental Procedure: Preclinical evaluation of PHI-101 for cellular and molecular potency in ovarian and breast cancer cell lines and patient derived primary cells; it includes biochemical binding assay, cellular assays, animal efficacy studies, combination study, signaling pathway effect examination, and cell cycle analysis.

Summary: CHK2 is a serine/threonine kinase and a cell cycle checkpoint regulator involved in the ATM-mediated DNA repair upon replication blocks and DNA damage. It has been proposed that Chk2 functions as a barrier to tumorigenesis by maintaining genomic stability, and this DNA damage induction is thought to prevent or delay genetic instability and tumorigenesis. The inhibition of CHK2 is a promising approach to achieve synthetic lethality of cancer cells when combined with PARP1 inhibitors. Solid cancer indications of PHI-101 was identified by the Chemiverse Network module which is an AI and Big data-based in-house drug discovery platform. Biochemical kinase assays for PHI-101 showed stronger affinity to CHK2 over CHK1 more than 5-fold. PHI-101 treatment of ovarian and breast cancer cells for 72 hrs elicit a synergistic lethal response in combination with PARP1 inhibitor Olaparib regardless of functional BRCA and P53 in the cells. PHI-101 also potentiates a countermeasure to dose-limiting toxicity triggered by genotoxic agents such as cisplatin and topotecan. The present results from in vivo and in vitro preclinical testing do demonstrate that PHI-101 is a highly potent inhibitor of CHK2 and may exert mono- and combinational therapeutic activity in ovarian and breast cancer model.

Conclusion: The preclinical evaluation of PHI-101, a novel CHK2 inhibitor, showed clear evidence of anticancer activity for refractory ovarian and breast cancer cells and improved efficacy in both in vitro and in vivo models. Consequently, PHI-101 is currently under investigation in Phase 1 clinical trials for relapsed or refractory ovarian cancer patients.

Citation Format: June H-J Han, Kyu-Tae Kim, Jeejin Im, Sojung Park, Min Kyung Choi, Inki Kim, Ky-Youb Nam, JeongHyeok Yoon. PHI-101, a potent and novel inhibitor of CHK2 in ovarian and breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1461.
Abstract 1731: EXS21546, a non-CNS penetrant A2AR-selective antagonist for anti-cancer immunotherapy
Authors: Payne Andrew , Fons Pierre , Alt Isabella , van Ham Joost , Taubert Christina , Bell Andy , Versluys Stephanie , Bertrand Florie , Visentin Virgile , Mirey Emilie , Pelissier Emilie , Paillasse Michael , Pagliarusco Sabrina , Vladimer Gregory , Whittaker Mark
Published: July 2021

Elevated levels of adenosine found in the tumor microenvironment have been highlighted as a potential mechanism contributing to the restricted efficacy of immune checkpoint inhibitors. While the advent of these inhibitors has brought significant benefit to patients with cancer, there is still significant unmet need even in disease indications for which these agents are approved. Adenosine has an immune-suppressive effect in tumors, and pre-clinical and early clinical evidence indicates that antagonists of the GPCR family of adenosine receptors are able to relieve that suppression and restore anti-tumor immune cell activity. EXS21546 is a non-furan, selective antagonist of the A2A receptor with low brain penetration. Using EXS21546, we show that activity at the A2A receptor is sufficient for complete restoration of T-cell function in the presence of high concentrations of adenosine analogue. Translational studies with EXS21546 have been undertaken using patient samples to better understand its activity in signaling and disease-relevant endpoints. We will present data characterizing the activity of EXS21546 ex vivo in patient-derived whole blood samples. Interrogation of primary cancer cells from pancreatic and lung cancer patients treated with EXS21546 ex vivo by phenotypic image-based screening, demonstrated that EXS21546 reduces the relative fraction of viable cancer cells while inducing an expansion of the viable CD8+ T cell fraction in the presence of high concentrations of an adenosine analogue. Together, these data indicate the potential for EXS21546 may have a role in cancer therapy. EXS21546 has completed pre-IND studies in preparation for initiation of first-in-human clinical studies.

Citation Format: Andrew Payne, Pierre Fons, Isabella Alt, Joost van Ham, Christina Taubert, Andy Bell, Stephanie Versluys, Florie Bertrand, Virgile Visentin, Emilie Mirey, Emilie Pelissier, Michael Paillasse, Sabrina Pagliarusco, Gregory Vladimer, Mark Whittaker. EXS21546, a non-CNS penetrant A2AR-selective antagonist for anti-cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1731.
Abstract 1807: T cell conditional knockout mouse model of the mitochondrial branched chain aminotransferase (BCATm) responds with delayed tumor growth to a lymphoma challenge
Authors: Adam Christie , Martin Alexander , Betar Rebekah , Foster Mercedes , Boyer Michael , Ananieva Elitsa
Published: July 2021

Enzymes in amino acid catabolism are emerging as attractive targets for cancer therapies. The mitochondrial branched-chain amino transferase (BCATm), an enzyme catalyzing the first step in leucine, valine, and isoleucine degradation, has been recently implicated in cancer growth but its role in T cell driven anti-cancer immunity has never been explored. To fulfill the gap in current scientific knowledge and address some of the challenges with lymphoma immunotherapies, we used the CD4-Cre-Lox recombination to create a conditional knockout mouse (T-BCATmKO) with CD4+ and CD8+ T cells deficient in the Bcat2 gene that encodes BCATm. Based on initial studies showing that a deletion of BCATm from T cells leads to increased glycolytic and oxygen metabolism and up-regulation of complex 1 of the mammalian target of rapamycin (mTORC1) signaling, we hypothesized that if BCATm is absent from T cells, this would stimulate T cell activation leading to improved T cell function in mice challenged with lymphoma. For this purpose, T-BCATmKO and T-BCATmfl/fl male mice (15-16 weeks old) were subcutaneously injected with 2.5x105 mouse lymphoma EG7-OVA cells. Tumor growth, animal weight, and food intake were recorded daily for a period of 20 days. Mice developed tumors around day 10 and this was not associated with weight loss or poor feeding of the mice as no changes in body weights or food intake between the different mouse groups were observed. Statistical analysis via one-way ANOVA revealed that T-BCATmKO mice had significantly delayed tumor growth compared to T-BCATmfl/fl mice (P= 0.05). In addition, CD4+ T cells isolated from T-BCATmKO mice released significantly more IFNγ after 48-72 hours of activation suggesting that CD4+ T cells from T-BCATmKO mice were more active than T cells from T-BCATmfl/fl mice. This study revealed that targeting BCATm in T cells may offer an advantage in mice to better fight lymphoma cancer and represents an attractive target for future immunotherapeutic anti-cancer approaches.

Citation Format: Christie Adam, Alexander Martin, Rebekah Betar, Mercedes Foster, Michael Boyer, Elitsa Ananieva. T cell conditional knockout mouse model of the mitochondrial branched chain aminotransferase (BCATm) responds with delayed tumor growth to a lymphoma challenge [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1807.
Abstract 1873: GlycoConnect™ ADCs based on topoisomerase 1 inhibitor exatecan (SYNtecan E™) show excellent in vivo efficacy and tolerability
Authors: van Delft Floris
Published: July 2021

Camptothecins form a powerful class of chemotherapy drugs (e.g. irinotecan, topotecan, belotecan), based on their ability to inhibit topoisomerase I. Some camptothecins, such as DXd and SN-38, have also proven powerful payloads for antibody-drug conjugates (ADCs), as exemplified by the recent market approval of Enhertu® and Trodelvy®, respectively. We have reported earlier that the native glycan of monoclonal antibodies is a priviliged conjugation site for ADCs (GlycoConnect™)1, while the highly polar spacer technology (HydraSpace™)2 enables the conjugation of any cytotoxic payload, providing ADCs with significantly expanded therapeutic index (TI) versus mainstream ADC technologies.

We here show that exatecan (DX-8951f), a clinically validated and potent campothecin, is readily combined with HydraSpace™ technology to provide linker-payload (SYNtecan E™). Homogeneous and stable GlycoConnect™ADCs were generated from trastuzumab and SYNtecan E™ and compared head-to-head with DXd or SN-38payload, as well as deruxtecan, the linker-payload applied in Enhertu®. Complete tumor regression was observed in a mouse xenograft study (BT-474) after a single dose, while safety studies in mouse corroborated the high tolerability of SYNtecan E™ ADCs. Taken together, these studies demonstrate the potential of SYNtecan E™ for application in stable and site-specific ADCs with excellent therapeutic index.

1 van Geel et al. Chemoenzymatic Conjugation of Toxic Payloads to the Globally Conserved N-Glycan of NativemAbs Provides Homogeneous and Highly Efficacious Antibody−Drug Conjugates. Bioconj. Chem. 2015, 26, 2233-2242.

2 Verkade et al. A Polar Sulfamide Spacer Significantly Enhances the Manufacturability, Stability, and Therapeutic Index of Antibody-Drug Conjugates. Antibodies 2018, 7, 12, doi:10.3390/antib7010012.

Citation Format: Floris van Delft. GlycoConnect™ ADCs based on topoisomerase 1 inhibitor exatecan (SYNtecan E™) show excellent in vivo efficacy and tolerability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1873.
Abstract 1910: Augmented secretion of IL-1α from mouse oral squamous cell carcinoma (OSCC) cells caused by the serum deprivation and hypoxia promotes immune-suppressive activity of mesenchymal stromal cells
Authors: Kondoh Nobuo , Matsunami Akihiro , Mizuno-Kamiya Masako , Umemura Naoki , Takayama Eiji , Kawaki Harumi , Ueno Kyouhei , Morimoto-Ito Hiroe , Muramatsu Yasunori , Sumitomo Shinichiro
Published: July 2021

Objectives; We have already reported that mouse oral squamous carcinoma (OSCC), Sq-1979-1, cells produce IL-1α which specifically enhances the immunosuppressive activity of co-cultured mesenchymal stromal, 10T1/2, cells (Morimoto-Ito, Open Dent J. 2019). In this report, we evaluated conditions promoting the expression of IL-1α of Sq-1979-1 cells to further enhance immunosuppressive function of the 10T1/2 cells, and also examined the expression in OSCC tissues.

Methods; Expression of IL-1α in Sq-1979-1 cells was evaluated by RT-PCR, western blots and enzyme-linked immune sorbent assay (ELISA). Conditioned mediums (CMs) from Sq-1979-1 cells were co-cultured with 10T1/2 cells and anti-CD3 antibody-stimulated mouse spleen cells. The production of interferon (IFN)- γ and IL-1α was evaluated using ELISA. The function of IL-1α in CM was examined by anti- IL-1α antibody. Immunohistochemical analysis of OSCC tissues was performed.

Results; The production of IL-1α from Sq-1979-1 cells was specifically enhanced in lower serum (0.5% or 1.0%FBS), or under hypoxia (1.0% oxygen) compared to that in the standard growth condition supplemented with 10% FBS under normoxia. Compared to standard CM, the CMs prepared in 0.5% and 1.0% FBS, or under hypoxia significantly reduced IFN-γ production from stimulated spleen cells co-cultured with 10T1/2 cells. These functions of the CMs completely abolished by anti- IL-1α antibody. Expression of IL-1α in OSCC tissues was prominent in the midst of carcinomatous cellular lesion, or nearby necrotic lesion, where the supply deficiency could be occurred.

Conclusions; The promotion of immunosuppressive activity of mesenchymal cells by Sq-1979-1 cells was specifically augmented in lower serum and hypoxic conditions, mediated by increased IL-1α production.

Citation Format: Nobuo Kondoh, Akihiro Matsunami, Masako Mizuno-Kamiya, Naoki Umemura, Eiji Takayama, Harumi Kawaki, Kyouhei Ueno, Hiroe Morimoto-Ito, Yasunori Muramatsu, Shinichiro Sumitomo. Augmented secretion of IL-1α from mouse oral squamous cell carcinoma (OSCC) cells caused by the serum deprivation and hypoxia promotes immune-suppressive activity of mesenchymal stromal cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1910.
Abstract 1929: Progesterone induces apoptosis by activation of caspase-8 and calcitriol via activation of caspase-9 pathways in ovarian and endometrial cancer cells in vitro
Authors: Mcglorthan Latoya , Paucarmayta Ana , Casablanca Yovanni , Maxwell George L. , Syed Viqar
Published: July 2021

Previously we have shown that progesterone and calcitriol induce apoptosis of cancer cells. However, the apoptotic mechanisms of the two agents have not been well characterized yet. Herein, we investigated the molecular mechanisms of how progesterone and calcitriol induce apoptosis in cancer cells. DNA fragmentation was upregulated by progesterone and calcitriol in ovarian and endometrial cancer cells. Time-dependent treatment of ovarian cancer cells, ES-2, and TOV-21G with progesterone enhanced caspase -8 activity after 12 h, whereas OV-90, TOV-112D, HEC-1A, and HEC-59 cells showed increased activity after 24h. Caspase 9 activity was increased in all cell lines after 24h treatment with calcitriol. Pretreatment of cancer cells with a caspase-8 inhibitor (z-IETD-fmk) or caspase-9 inhibitor (Z-LEHD-fmk) significantly attenuated progesterone and calcitriol induced caspase-8 and caspase-9 expression, respectively. The expression of FasL, Fas, FAD, and pro-caspase-8, which constitute the death-inducing signaling complex (DISC), was upregulated in progesterone treated cancer cells. Knockdown of FAS or FADD with specific siRNAs significantly blocked progesterone-induced caspase-8. Cleavage of the BID was not affected by caspase-8 activation suggesting the absence of cross-talk between caspase-8 and caspase-9 pathways. Calcitriol treatment decreased mitochondrial membrane potential and increased the release of cancer cytochrome C. These findings indicate that progesterone induces apoptosis through activation of caspase-8 and calcitriol through caspase-9 activation in cancer cells. A combination of progesterone-calcitriol activates both extrinsic and intrinsic apoptotic pathways in cancer cells.

Citation Format: Latoya Mcglorthan, Ana Paucarmayta, Yovanni Casablanca, George L. Maxwell, Viqar Syed. Progesterone induces apoptosis by activation of caspase-8 and calcitriol via activation of caspase-9 pathways in ovarian and endometrial cancer cells in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1929.
Abstract 1945: Modulation of intracellular redox milieu regulates Mcl-1 levels and sensitizes venetoclax resistant cancer cells
Authors: Lai Jolin Xiao , Pervaiz Shazib
Published: July 2021

Mcl-1, a member of the Bcl-2 family of anti-apoptotic proteins is commonly amplified in malignant cancers and has been implicated in chemotherapy resistance. More recently, it has been reported to mediate resistance to the Bcl-2 specific BH3 mimetic, venetoclax (ABT199). The protein stability of Mcl-1 is regulated largely by post-translational modifications (PTMs) such as phosphorylation and ubiquitination. Where phosphorylation of Thr163 residue at the PEST domain region by kinases result in Mcl-1 stability and extended protein half-life, phosphorylation of Ser159 residue leads to protein degradation via proteasome pathway. Given the importance of PTMs in regulating Mcl-1, identification of signaling pathways that could modulate PTMs of Mcl-1 to thereby sensitize tumors to chemotherapy have been explored extensively. The intracellular redox milieu has been widely reported to modulate protein-protein signaling as well as inducing PTMs, where different reactive oxygen species (ROS) have also been shown to mediate differential effects. For example, enhanced production of O2- (by either inhibition or downregulation of SOD1/SOD2) could mediate tumorigenicity and chemoresistance. To that end, our group and others have also previously reported the oncogenicity of superoxide (O2-), where an elevated O2- level mediates enhanced anti-apoptotic activity against chemotherapeutic agents through sustained Bcl-2 phosphorylation and the inhibition of O2- production conversely sensitized cells to chemotherapy. Nonetheless, the exact mechanisms of how O2- exerts its pro-survival effects remain elusive. Our preliminary findings now suggest that elevated intracellular O2- levels induces Mcl-1 stability in cancer cells through PTMs as a potential mechanism of chemotherapy resistance. Increased intracellular O2- levels induced Mcl-1 through phosphorylation of Thr163 residue of Mcl-1, which in turn reduced ubiquitination dependent degradation of Mcl-1. Importantly, increased O2- level increased resistance to cell death induced by Mcl-1 specific BH3 mimetic, S63845 and conversely, reducing O2- levels resulted in sensitization of intrinsically venetoclax resistant leukemia cells to venetoclax induced cell death. These results provide a novel insight into how the intracellular redox state could impact upon cancer cell viability and therapy resistance.

Citation Format: Jolin Xiao Lai, Shazib Pervaiz. Modulation of intracellular redox milieu regulates Mcl-1 levels and sensitizes venetoclax resistant cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1945.
Abstract 1970: Preclinical candidate TQB3824, a small molecule inhibitor of CDC7, shows strong antitumor efficacy in colorectal and pancreatic tumor models
Authors: Li Gang , Zhang Xiquan , Yang Ling , Tian Xin , xiong Zhong , Hu Lihong , xia Yuanfeng , chan Chi-chung , Ding Charles Z. , Chen Shuhui
Published: July 2021

Objective: Cell division cycle 7 (CDC7), a receptor serine/threonine kinase which features high-affinity with protein DBF4, plays an important role in DNA replication and DNA damage response via MCM2 phosphorylation. CDC7 has been reported to be up-regulated by about 50% in various human cancers and is being investigated as a therapeutic target in clinical trials. The purpose of this study is to investigate the in-vitro and in-vivo antitumor activities of TQB3824, a small molecule of CDC7 kinase inhibitor, in preclinical models with CDC7 overexpression.

Method: Kinase inhibition activities of TQB3824 were determined with CDC7/DBF4 kinase assays. Cellular anti-proliferative activities were evaluated in COLO205 cell line and NCI-H226 cell line, which features CDC7 overexpression and no CDC7 expression, respectively. Three CDX models, colorectal cancer COLO205/SW620 and pancreatic cancer CAPAN-1 with KRAS mutation, were used to test the efficacy of TQB-3824 in vivo.

Result: TQB3824 showed potent activities in both kinase inhibition and COLO205 cell anti-proliferation, with IC50 of 2.9 nM and 14.5 nM, separately. In contrast, TQB3824 showed much weaker anti-proliferative activity in NCI H226 cells with IC50 of 8154 nM. TQB3824 displayed strong antitumor efficacy in CDC7 highly expressed colorectal cancer CDX model COLO205 (TGI = 77% @5 mpk, BID), SW620 CDX model (TGI = 100% @5 mpk, BID), and pancreatic cancer CAPAN-1 CDX model (TGI = 115% @6 mpk, BID).

Conclusion: We have identified a novel potent CDC7 inhibitor TQB3824, which shows high antitumor efficacy in CDC7 overexpressed solid tumor models. TQB3824 represents a promising clinical candidate for treating solid tumors with high CDC7 expression.

Citation Format: Gang Li, Xiquan Zhang, Ling Yang, Xin Tian, Zhong xiong, Lihong Hu, Yuanfeng xia, Chi-chung chan, Charles Z. Ding, Shuhui Chen. Preclinical candidate TQB3824, a small molecule inhibitor of CDC7, shows strong antitumor efficacy in colorectal and pancreatic tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1970.
Abstract 202: Identification of survival associated hub genes in prostate cancer patients from the TCGA database
Authors: Reyes Niradiz , Tiwari Raj , Geliebter Jan
Published: July 2021

Background: Prostate cancer is the most frequently diagnosed malignancy and the fourth leading cause of cancer-related death in the global male population. Although the disease has a relatively low mortality rate with some patients surviving for 10-20 years after treatment, others respond poorly to treatment and die of metastatic disease within 2-3 years. Therefore, there is an urgent need to develop strategies to identify patients with clinically significant prostate cancer requiring aggressive treatment to improve survival, while sparing others unnecessary side effects. The purpose of this study was to identify survival associated genes in prostate cancer patients from the TCGA database using bioinformatics tools.

Methods: Data from prostate cancer patients in the TCGA database were divided into two study groups: a high and a low expression group, relative to the median expression. The Gene Expression Profiling Interactive Analysis (GEPIA2) tool was used for the identification of the most differential survival genes. Metascape bioinformatics tool was subsequently used for clustering of genes based on processes, pathway enrichment analysis, and construction of Protein-Protein Interaction (PPI) network. Metascape was also used for molecular Complex Detection (MCODE) to identify the genes with the highest degree of connection, known as hub genes, and to screen modules of the PPI network.

Results: Bioinformatics analysis allowed the identification of 361 genes whose expression levels were significantly associated with overall survival in prostate cancer patients from the TCGA. Survival associated genes were primarily enriched in mRNA processing, DNA repair, ncRNA processing, DNA replication, macromolecule methylation, among others. The 12 most connected genes were selected as hub genes and Kaplan-Meier analysis was used to verify survival associated with this set of genes. Hub genes included several splicing factors and components of the processing machinery of cellular pre-mRNAs.

Conclusions: These hub genes may reveal basic mechanisms underlying the development of clinically relevant prostate cancer and contribute to the identification of novel markers for prognosis of this cancer.

Citation Format: Niradiz Reyes, Raj Tiwari, Jan Geliebter. Identification of survival associated hub genes in prostate cancer patients from the TCGA database [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 202.
Abstract 2053: Molecular characterization of BRCA1c.5339T>C missense mutation in DNA damage response of triple-negative breast cancer cells
Authors: Lee Jeong Dong , Kim Min Hwan , Choi Yeon A , Ryu Won-Ji , Han Hyun Ju , Choi Ae Ran , Kim Tae Yeong , Sohn Joo Hyuk
Published: July 2021

Purpose Recent studies re-classified the c.5339T->C; p.Leu1780Pro (L1780P) BRCA1 missense mutation as “likely pathogenic” in ACMG classification, which shows high prevalence in Korean population. This study aims to reveal the molecular mechanisms and therapeutic relevance of BRCA1 L1780P mutation in DNA damaging response of triple-negative breast cancer (TNBC) cells.

Method We established MDA-MB 231 and HCC1937 TNBC cell lines expressing BRCA1 wild-type and BRCA1 L1780P by stable transfection of plasmid DNAs. We performed cell proliferation assays of the TNBC cell lines with treatment of olaparib and carboplatin. We compared the protein and mRNA expression level of RAD51 in BRCA1 wild-type and L1780 transfected TNBC cell lines by western blot and RT-PCR, and BRCA1-mediated DNA damaging responses were evaluated by immunofluorescence staining of RAD51 upon olaparib and carboplatin treatment. The growth inhibitory potential of RAD51 inhibitor, RI-1 was tested in BRCA1 L1780P transfected TNBC cell lines.

Results BRCA1 L1780P transfected TNBC cells showed higher migration and invasion capacity, as well as increased sensitivity to olaparib and carboplatin compared to BRCA1 wild-type transfected cells. The induction of RAD51 expression on carboplatin treatment was significantly decreased in BRCA1 L1780P TNBC cells compared with BRCA1 wild-type cells. BRCA1 L1780P transfected TNBC cells showed also showed reduced nuclear RAD51 foci formation on carboplatin and olaparib treatment. The molecular interaction between p-BRCA1 and ATM was decreased by BRCA1 L1780P introduction in TNBC cells, suggesting BRCA1 L1780P mutation disrupts binding of p-BRCA1-ATM. In a cell proliferation assay, BRCA1 L1780P transfected TNBC cells were highly sensitive to RAD51 inhibitor (IC50 = 4.15μM).

Conclusion This study shows BRCA1 L1780P mutation causes defects in DNA damage responses of TNBC cells by disrupting molecular interaction between p-BRCA1 and ATM, resulting in RAD51 downregulation. The combinatory inhibition of RAD51 and PARP is a candidate strategy for TNBCs with BRCA1 L1780P mutation.

Keywords: Triple-negative Breast Cancer; BRCA1 L1780 Mutation; Homologous Recombination Deficiency; RAD51

Citation Format: Jeong Dong Lee, Min Hwan Kim, Yeon A Choi, Won-Ji Ryu, Hyun Ju Han, Ae Ran Choi, Tae Yeong Kim, Joo Hyuk Sohn. Molecular characterization of BRCA1c.5339T>C missense mutation in DNA damage response of triple-negative breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2053.
Abstract 2073: Co-Targeting PARP and ATR in biliary tract cancer
Authors: Nam Ah Rong , Jin Mei Hua , Oh Kyoung-Seok , Seo Hye Rim , Kim Jae-Min , Bang Ju-Hee , Yoon Jeesun , Kim Tae-Yong , Oh Do-Youn
Published: July 2021

Background: Targeting DNA damage response (DDR) has potential anti-tumor effects in diverse cancer types. Homologous-recombination DDR gene mutations are found in 28.9% of biliary tract cancer (BTC). We aimed to evaluate the anti-tumor effects of olaparib (PARP inhibitor) with or without ceralasertib (ATR inhibitor) in BTC.Methods: Ten BTC cell lines (SNU245, SNU308, SNU478, SNU869, SNU1079, SNU1196, HuCCT-1, TFK-1, SNU2670, and SNU2773) were tested to evaluate the anti-tumor effects of olaparib alone and in combination with ceralasertib. MTT assay, colony formation assay, cell cycle analysis, western blot, comet assay and co-culture with human PBMC were used as experimental methods. Tumor xenograft model was established to test olaparib with or without ceralasertib in vivo.Results: Olaparib alone showed moderate anti-proliferative effects in all BTC cells and increased p-ATR and PD-L1 expression. Olaparib plus ceralasertib showed synergistic anti-proliferative effects and led to DNA damage breaks in vitro. Ceralasertib also downregulated PD-L1 level through p-STAT3 and YAP pathway with or without human PBMC conditions. In SNU478-xenograft models, Olaparib plus ceralasertib combination significantly suppressed tumor growth and downregulated PD-L1 and YAP, compared with monotherapy. It also effectively reduced CXCR2 and CXCR4 expression. Conclusion: Combination of olaparib plus ceralasertib showed potent anti-tumor effects in BTC cells. This study could provide the preclinical evidence of development of PARP and ATR dual inhibition in BTC patients. Clinical trial using olaparib and ceralasertib combination in advanced BTC is ongoing (ClinicalTrials.gov Identifier: NCT04298021).

Citation Format: Ah Rong Nam, Mei Hua Jin, Kyoung-Seok Oh, Hye Rim Seo, Jae-Min Kim, Ju-Hee Bang, Jeesun Yoon, Tae-Yong Kim, Do-Youn Oh. Co-Targeting PARP and ATR in biliary tract cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2073.
Abstract 2103: Distinct methylation patterns correlate with unique clinical and genomic profiles of brainstem gliomas
Authors: Chen Lee H. , Pan Changcun , Wang Sizhen , Yan Hai , Zhang Liwei
Published: July 2021

Gliomas of the brainstem and surrounding regions are devastating brain tumors with the highest mortality rates among all cancers. The locations of tumors make surgical resection difficult due to the risk of perioperative mortality. To understand the genetics and molecular biology of this disease, we performed a comprehensive study, combining epigenetic and genomic analyses with clinical features on 126 brainstem gliomas, including 33 diffuse intrinsic pontine gliomas. Based on DNA methylation data, we identified four distinct clusters named H3-Pons, H3-Medulla, IDH, and PA-like, each associated with unique genomic and clinical profiles. Most of the tumors within H3-Pons and H3-Medulla harbored H3F3A mutations, but tumors in these two clusters use different escaping mechanisms for DNA damage response pathway. Most of the tumors in H3-Pons showed TP53 mutations, while H3-Medulla contain PPM1D mutations. We also analyzed the lengths of telomeres in these tumors by whole genome sequencing data, showing striking difference between clusters, suggesting the mechanisms of telomere maintenance differ between different subtypes of brainstem gliomas. Structural variations and alternative splicing based on RNA sequencing demonstrated possible different transcriptome profiling in methylation clusters, and pathway analysis showed different mechanisms in these samples. Our findings suggest that the integration of DNA methylation data into diagnosis could be utilized to better understand brainstem glioma and better defining the classification, therefore guiding future clinical management of patients.

Citation Format: Lee H. Chen, Changcun Pan, Sizhen Wang, Hai Yan, Liwei Zhang. Distinct methylation patterns correlate with unique clinical and genomic profiles of brainstem gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2103.