bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1404: Loss of adenomatous polyposis coli induces DOX resistance through upregulation of ABC transporters
Authors: Stefanski Casey D. , Prosperi Jenifer R. , Milac Lauren
Published: July 2021

Chemoresistance is a leading cause of breast cancer related deaths. Therefore, understanding the molecular basis for chemoresistance is essential for novel therapeutic advancement improving patient outcome. The Adenomatous Polyposis Coli (APC) tumor suppressor is lost in up to 70% of sporadic breast cancer; however, little is known about how APC loss contributes to chemoresistance. Using mammary tumor cells isolated from the ApcMin/+ mouse crossed to the Polyoma middle T antigen (PyMT) transgenic model, we were the first to show that APC loss decreased doxorubicin (DOX) induced apoptosis. Therefore, we examined the mechanisms contributing to DOX resistance with APC loss to identify combination therapy options. We previously made the novel observation that APC loss in MMTV-PyMT;ApcMin/+ cells activated signal transducer and activator of transcription 3 (STAT3) thereby increasing the expression of the drug efflux pump, multidrug resistance protein 1 (MDR1). ATP-binding cassette (ABC) transporters, such as MDR1, are one of the most well-known contributors to drug resistance. These ABC transporters are capable of exporting drugs from the cell preventing apoptosis. Decreased intracellular DOX accumulation was observed in APC-deficient cells suggesting enhanced drug efflux. To investigate this decreased intracellular DOX accumulation, we measured the expression and activity of the drug export pumps, MDR1 and multidrug resistance protein 1 (MRP1). APC-deficient cells also have increased expression of MRP1. We used a calcein incorporation assay and demonstrated that APC loss increased MDR1 activity, which was restored by an MDR1 inhibitor. In addition, MDR1 inhibition sensitized the MMTV-PyMT;ApcMin/+ cells to DOX-mediated apoptosis. MRP1 inhibition through genetic manipulation will be used to assess MRP1 activity using the calcein AM assay and its contribution to DOX resistance. MDR1 and MRP1 inhibition will also be used to restore intracellular DOX accumulation. Future studies including evaluating human tumor protein lysates will for APC, MDR1, and MRP1 expression. Correlation studies will be used to determine whether loss of APC correlates with either high expression of MDR1 or MRP1. Taken together, APC loss mediates DOX resistance via exporting DOX demonstrating the potential use of combination therapy to overcome chemoresistance.

Citation Format: Casey D. Stefanski, Jenifer R. Prosperi, Lauren Milac. Loss of adenomatous polyposis coli induces DOX resistance through upregulation of ABC transporters [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 1404.
Abstract 1413: Targeting the RNA-binding protein HuR to overcome chemoresistance in triple-negative breast cancer
Authors: Wei Lanjing , Zhang Qi , Zhong Cuncong , Aubé Jeffrey , Welch Danny R. , Wu Xiaoqing , Xu Liang
Published: July 2021

Patients with triple-negative breast cancer (TNBC) have a lower 5-year relative survival rate (77%) than overall for breast cancer (91%). Chemotherapy remains the primary choice for the systemic treatment of TNBC. However, patients frequently develop resistance to conventional chemotherapy, resulting in poorer prognosis and higher recurrence than other subtypes of breast cancer. Therefore, overcoming chemotherapy resistance is critical for the successful treatment of TNBC. The RNA-binding protein Hu antigen R (HuR) plays an important role in chemotherapy resistance. HuR is a posttranscriptional regulator, which can stabilize target mRNAs by binding to U- or AU-rich elements (ARE) mainly in 3' untranslated region (UTR) of mRNA and upregulate their translation. The encoded proteins are implicated in multiple cancer hallmarks, including chemoresistance. The overexpression of HuR, especially accumulated cytoplasmic expression, is related to chemoresistance in many types of cancer. We hypothesize that inhibition of HuR function by disrupting its interaction with mRNA can accelerate the decay of mRNA and thus reduce the translation of proteins responsible for chemoresistance.Recently, our lab reported a small molecule HuR inhibitor, KH-3, which potently inhibits HuR function by disrupting the HuR-mRNA interactions. KH-3 effectively suppresses growth and invasion of TNBC cells in vitro and in vivo. In this study, we assessed whether HuR is a target for overcoming chemoresistance and evaluated whether KH-3, as a small molecule HuR functional inhibitor, could enhance the efficacy of chemotherapy for TNBC cells. To determine whether HuR inhibition overcomes acquired chemoresistance of TNBC, we generated cell sublines derived from human MDA-MB-231 with acquired resistance against docetaxel or doxorubicin. KH-3 could synergize TNBC cells to chemotherapy in vitro and in vivo. Interestingly, KH-3 treatment could re-sensitize chemoresistant TNBC cells to drugs, indicating that HuR inhibition can overcome acquired chemoresistance. Regarding mechanisms of action, several pathways and HuR direct target mRNA are implicated in docetaxel and doxorubicin resistance, but detailed molecular mechanisms are still under investigation. This study provides a new strategy to overcome chemotherapy resistance and improve the survival of TNBC.

Citation Format: Lanjing Wei, Qi Zhang, Cuncong Zhong, Jeffrey Aubé, Danny R. Welch, Xiaoqing Wu, Liang Xu. Targeting the RNA-binding protein HuR to overcome chemoresistance in triple-negative breast 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 1413.
Abstract 1423: Shikonin impairs the growth of docetaxel-resistant prostate cancer cells by necroptosis
Authors: Markowitsch Sascha D. , Juetter Kira M. , Schupp Patricia , Hausschulte Kristine , Vakhrusheva Olesya , Cinatl Jindrich , Michaelis Martin , Efferth Thomas , Haferkamp Axel , Juengel Eva
Published: July 2021

Introduction: Prostate carcinoma (PCa) is the most common malignancy in men. Androgen-targeted therapy and chemotherapy are currently the treatment of choice for advanced stages. Due to resistance towards these therapies, prognosis remains poor and new treatment options are urgently required. Shikonin (SHI) from Traditional Chinese Medicine (TCM) might be promising, since it induces anti-tumor effects in different tumor entities. However, data on PCa are few, and data on resistant PCa are not existent.

Material and Methods: Parental (=sensitive) and docetaxel-resistant PCa cell lines, PC3, DU145, LNCaP, and 22Rv1 were exposed to SHI [0.1 - 1.5 μM] for 24, 48, or 72 hours. Untreated cells served as controls. Tumor cell growth, proliferation, cell cycle, and the expression of cell cycle regulating proteins were assessed. Several cell deaths, like apoptosis, necrosis and necroptosis as well as the metabolic activity were evaluated.

Results: Time- and dose-dependent exposure to SHI significantly reduced tumor cell growth and proliferation in parental and docetaxel-resistant PCa cells, compared to the untreated controls. This was accompanied by cell cycle arrest in the G2/M phase in parental PC3 and docetaxel-resistant DU145 and S phase arrest in resistant 22Rv1, associated with modulated expression of cell cycle regulating proteins. Significant apoptotic effects were observed in parental and docetaxel-resistant PC3, DU145, 22Rv1, and resistant LNCaP. Moreover, SHI induced necroptosis in all parental and resistant PCa cells, as shown by additional application to the necroptosis inhibitor necrostatin-1. In line with this, RIP-1 expression enhanced under SHI exposure. In contrast, SHI did not alter the metabolic activity of the PCa cells.

Conclusion: Significant anti-tumor effects are apparent in parental but also in docetaxel-resistant PCa cells after SHI application. Thus, adding SHI to standard therapies might be a promising treatment strategy for patients with advanced prostate cancer. Further investigations are necessary to verify our findings.

Funding: Friedrich-Spicker-Stiftung (2017).

Acknowledgments: The main portion of the results presented here are part of the MD thesis of Kira M. Juetter at the Department of Urology and Pediatric Urology, University Medical Center Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.

Citation Format: Sascha D. Markowitsch, Kira M. Juetter, Patricia Schupp, Kristine Hausschulte, Olesya Vakhrusheva, Jindrich Cinatl, Martin Michaelis, Thomas Efferth, Axel Haferkamp, Eva Juengel. Shikonin impairs the growth of docetaxel-resistant prostate cancer cells by necroptosis [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 1423.
Abstract 1440: Novel imipridone ONC206 suppresses ovarian cancer progression through modulating immune cell response
Authors: Yeung Chi Lam Au , Hu Wen , Ferri-Borgogno Sammy , Tarapore Rohinton S. , Allen Joshua E. , Lu Karen H. , Mok Samuel C.
Published: July 2021

Advanced ovarian cancer (stages III and IV) is the most lethal gynecologic malignancy in the United States. Survival of this cancer has not improved to a major extent over the past decade. High-grade serous ovarian cancer (HGSC), in particular, is notable for its initial sensitivity to chemotherapy using platinum and taxane combination following debulking surgery. However, the vast majority of these cancers (>75-80%) recur within 12-24 months after diagnosis, and patients die of progressively chemotherapy-resistant disease. The identification of prognostic or predictive markers, for ovarian cancer is crucial to the development of therapeutic targets and thus improvement of survival. ONC201 is the first clinical bitopic antagonist of dopamine receptor D2 (DRD2), that is well tolerated and currently being investigated in several clinical trials for oncology. ONC206 is a chemical derivative of ONC201 with the same impridone core structure, which is also a DRD2 antagonist that exhibits distinct receptor pharmacology and nanomolar potency in various preclinical cancer models. However, the effects of ONC206 on HGSC progression and the mechanism of action have not been thoroughly explored. Preliminary data demonstrated that overexpression of DRD2 is associated with poor overall survival rates in patients with advanced stage HGSC. ONC206-treated HGSC cells demonstrated significantly lower growth rates and higher percentage of apoptotic cells than ONC201-treated cells did in vitro. Besides, intraperitoneal injection of ONC206 (100 mg/kg) twice a week into HGSC-bearing immunocompetent mice demonstrated decreased tumor volume in vivo. In addition, by using suspension mass cytometry with a panel of 28 antibodies, fresh tumor tissues from ONC206-treated mice showed markedly increase in intratumoral NK cells and activated CD8+ T cells densities. These data suggest that ONC206 is more potent than ONC201 in suppressing HGSC growth directly. In addition, ONC206 may also suppresses HGSC growth through activating immune cell response in tumor tissues. Further studies that define the molecular mechanism by which DRD2 modulates the tumor suppressive effect of ONC206 on HGSC cells by suppressing HGSC directly or enhancing anti-tumor immune cell activity will be perform to establish ONC206 as a novel therapeutic agent in treatment of HGSC patients.

Citation Format: Chi Lam Au Yeung, Wen Hu, Sammy Ferri-Borgogno, Rohinton S. Tarapore, Joshua E. Allen, Karen H. Lu, Samuel C. Mok. Novel imipridone ONC206 suppresses ovarian cancer progression through modulating immune cell response [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 1440.
Abstract 1445: A nuclear localizing peptide that targets glioblastoma
Authors: Lewis Calvin D. , Singh Abhay , Kapoor Vaishali , Hallahan Dennis E.
Published: July 2021

Glioblastoma (GBM) is one of the most aggressive and fatal primary brain neoplasms with a median survival of less than 15 months even after current standard of cares including surgical resection, radiotherapy and systemic therapy. Although systemic anticancer agents, such as temozolomide, are used as the standard of care for GBM, therapeutic efficacy is limited due to the off-target systemic toxicity of traditional chemotherapeutics. Targeted systemic therapy is emerging as an important treatment strategy for cancer therapy. Phage display peptide library was used to discover peptides that undergo endocytosis in GBM. We have identified a novel peptide that accumulates intracellularly in multiple GBM cell lines. Intracellular localization was quantified by FACS analysis of the FITC-labeled peptide. As compared to untreated GBM cells, D54, U251 and SF295 human GBM cell lines treated with 5.55 µM of peptide-FITC conjugate showed a significant FITC-positive shift on FACS analysis with 83%, 85% and 71% of cells internalizing the peptide, respectively. Confocal laser scanning microscopy experiments further confirm the intracellular targeting of the FITC-peptide in D54, U251 and SF295 GBM cell lines with associated peptide nuclear localization. Further studies are underway to elucidate the microscopic biodistribution of the nuclear homing peptide (NHP) in GBM mouse models. This work is significant as a novel cell surface, intracellular or nuclear binding partner may be identified for peptide-targeted cancer drug therapy. Furthermore, the NHP has potential to be translated to the clinic as targeted therapy for GBM patients in the form of a peptide-drug conjugate.

Citation Format: Calvin D. Lewis, Abhay Singh, Vaishali Kapoor, Dennis E. Hallahan. A nuclear localizing peptide that targets glioblastoma [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 1445.
Abstract 1462: KF1601, a novel orally bioavailable inhibitor of Bcr-Abl T315I, without inducing thrombotic microangiopathy
Authors: Kwon HyunJin , Ahn Sung-Min , Chang Kiho , Kim WooSik , Khan Amir , LEE Doohyun , Lee Seungyeon , Han Ye Ri , Im Chun Young
Published: July 2021

Targeting Bcr-Abl with tyrosine kinase inhibitors (TKIs) has revolutionized the treatment of chronic myeloid leukemia (CML) by significantly improving patients' survival. However, the gatekeeper mutation T315I confers resistance to TKIs targeting Bcr-Abl, presenting a formidable task in CML's clinical management. Ponatinib is the only approved drug for Bcr-AblT315I, but often accompanies severe, life-threatening side effects. Herein, we report KF1601, a novel orally bioavailable TKI: 1) KF1601 inhibited kinase functions of both Bcr-AblWT and Bcr-AblT315I with nanomolar IC50 values; 2) In xenograft models using Ba/F3 Bcr-AblT315I cell line, it showed promising in vivo antitumor efficacy, comparable to that of ponatinib; 3) In animal models, it did not cause thrombotic microangiopathy, a major mechanism of ponatinib's toxicity. In summary, KF1601 is a promising drug candidate for safely treating CML patients with drug-resistant Bcr-AblT315I mutation.

Citation Format: HyunJin Kwon, Sung-Min Ahn, Kiho Chang, WooSik Kim, Amir Khan, Doohyun LEE, Seungyeon Lee, Ye Ri Han, Chun Young Im. KF1601, a novel orally bioavailable inhibitor of Bcr-Abl T315I, without inducing thrombotic microangiopathy [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 1462.
Abstract 1482: M4645 is a potent and highly selective inhibitor of disease relevant cKIT mutations for the treatment of metastatic or recurrent GIST
Authors: Linde Nina , Blum Andreas , Dorsch Dieter , Graedler Ulrich , Busch Michael , Glaser Nina , Petersson Carl , Ruff Aaron , Sherbetjian Eva , Esdar Christina
Published: July 2021

Oncogenic mutations in cKIT in exons 9 and 11 are the main driver of gastrointestinal stromal tumors (GIST). Imatinib is standard of care in 1L in unresectable metastatic or recurrent GIST, yet secondary resistance mutations in exons 13/14 and 17/18 of the cKIT kinase domain frequently arise limiting efficacy. Currently approved 2L and 3L therapies sunitinib and regorafenib target these mutations only to some extent and show limited clinical benefit. Even with the recent approval of ripretinib as 4L treatment, a high unmet medical need remains for patients with imatinib resistance mutations in exon13/14. M4645 was designed to particularly inhibit the frequent V654A resistance mutation in exon 13 of cKIT. Based on cKIT inhibitor scaffolds identified within the Merck compound collection, a 3,5,6-substituted indazole-lead was discovered. Substituent optimization in the 5- and 6-positions of the core scaffold resulted in highly selective kinase inhibitors. Through variation at the 3-position, potency and physicochemical properties were optimized, resulting in the candidate molecule M4645 which combined potency, kinase selectivity, and solubility with a good safety profile. The excellent kinase selectivity could be rationalized by the crystal structure of cKIT V654A mutant kinase domain in complex with M4645. M4645 showed potent inhibition of cKIT autophosphorylation and of downstream P-ERK1/2 and P-AKT signaling in cell lines bearing activating and resistance mutations of cKIT. Dose-dependent inhibition of cKIT activation was demonstrated in a GIST xenograft model expressing the cKIT resistance mutation V654A in exon 13. Strong antitumor activity was observed in cell line and patient-derived GIST xenograft models with this imatinib resistance mutation. Compared to imatinib, M4645 induced prolonged anti-tumor response in a GIST model with a primary activating mutation of cKIT. In summary, the favorable profile and strong antitumor activity, particularly in GIST models expressing the V654A resistance mutation, suggests superiority of M4645 compared to currently available > 2L treatment options for unresectable metastatic or recurrent GIST patients.

Citation Format: Nina Linde, Andreas Blum, Dieter Dorsch, Ulrich Graedler, Michael Busch, Nina Glaser, Carl Petersson, Aaron Ruff, Eva Sherbetjian, Christina Esdar. M4645 is a potent and highly selective inhibitor of disease relevant cKIT mutations for the treatment of metastatic or recurrent GIST [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 1482.
Abstract 1487: Cytotoxic CD4+ T cells contribute to anti-tumor immune responses in NSCLC
Authors: Lau Denise , Khare Sonal , Reiman Derek , Rand Tim , Salahudeen Ameen A. , Khan Aly
Published: July 2021

Immune checkpoint blockade (ICB) is widely used to treat non-small cell lung cancer (NSCLC) patients and works by inhibiting the PD-1/PDL1 axis to reinvigorate exhausted T cells. In the prevailing model, the primary mechanism for direct tumor cell killing occurs through cytotoxic CD8+ T cells. Here, we use single-cell multi-omic profiling (a combination of single-cell RNA sequencing, TCR sequencing, and surface protein profiling) in 10 NSCLC patients to identify a population of CD4+ T cells that are tumor-infiltrating, clonally expanded, and express a cytotoxic gene program. Concordantly, we found in the same patients a subpopulation of tumor cells with elevated HLA class II expression, suggesting a mechanism for tumor-mediated antigen presentation to CD4+ T cells. Finally, we show that a cytotoxic CD4 gene signature is associated with improved progression-free survival in a cohort of 180 NSCLC patients treated with ICB regimens, including those with loss of heterozygosity at the HLA class I locus. Overall, these results suggest a model where cytotoxic CD4+ T cells can perform direct tumor cell killing in a class II restricted manner and that their presence is associated with favorable ICB outcomes in NSCLC.

Citation Format: Denise Lau, Sonal Khare, Derek Reiman, Tim Rand, Ameen A. Salahudeen, Aly Khan. Cytotoxic CD4+ T cells contribute to anti-tumor immune responses in NSCLC [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 1487.
Abstract 1534: Mesothelin isoform 2 is a novel target for allogenic CARγδT cell therapy in solid tumors
Authors: Wang Xiaohong , Chen Yibin , Gopisetty Anupama , Mirandola Leonardo , Piccotti Lucia , Nguyen Quynh , Chiriva-Internati Maurizio
Published: July 2021

Mesothelin (MSLN) is a tumor-associated antigen over-expressed on the cell surface of various malignant tumor cells, including majority of mesothelioma and ovarian cancer. MSLN-directed therapy has been intensively studied in preclinical and clinical settings. However, the clinical efficacy and safety of mesothelin-targeted therapy remains to be demonstrated. To identify a safe and effective target for CAR-T cell therapy in solid tumors, we used artificial intelligent platform developed with public and private RNA transcription database to identify cancer-associated antigens caused by alternative spicing. One of interesting targets is an alternative spicing isoform from MSLN. Human MSLN transcript has at least three isoforms. The isoform 1 is the predominant transcript detected in normal and tumor tissues and has been a promising target for cancer immunotherapy. The isoform 2 is the minor transcript using alternatively spliced exons producing 8 additional amino acids insertion compared to isoform 1. The isoform 3 produces a truncated and soluble MSLN. Our data demonstrated that MSLN isoform 2 is specifically expressed in ovarian cancers but not normal tissues, confirmed by Q-PCR studies. Furthermore, we generated mouse hybridoma antibodies specifically targeting MSLN isoform 2. The antibody specificity was screened and confirmed by ELISA-based reaction to MSLN isoform 2-specific peptide and flow cytometry-based binding to 293T cells overexpressing MSLN isoform 2 but not isoform 1 proteins. We further detected the endogenous MSLN isoform 2 expression in human mesothelioma cell line NCI H226 and further confirmed MSLN isoform 2 expression on human primary mesothelioma and ovarian cancer tissue but not normal tissues by immunohistochemistry staining. To study if targeting MSLN isoform 2 with chimeric antigen receptor (CAR) can control the tumor growth, we made CAR retrovirus construct and showed that genetically modified allogenic gamma-delta T cells expressing CAR for MSLN isoform 2 can kill human mesothelioma cells in vitro and in vivo. In summary, we have demonstrated that MSLN isoform 2 is a tumor-specific antigen, which can be targeted for CAR-T cell therapy.

Citation Format: Xiaohong Wang, Yibin Chen, Anupama Gopisetty, Leonardo Mirandola, Lucia Piccotti, Quynh Nguyen, Maurizio Chiriva-Internati. Mesothelin isoform 2 is a novel target for allogenic CARγδT cell therapy in solid 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 1534.
Abstract 1549: ACLX-001, a novel BCMA-targeted CAR-T cell therapy that can be activated, silenced, and reprogrammed in vivo with soluble protein adapters in a dose dependent manner
Authors: Edwards Justin P. , Buonato Janine , LaFleur David , Swers Jeffrey , Mu Jenny , Zaritskaya Liubov , Ng Sinnie , Gupta Ankit , Wang Hui , McCullough Samantha , Hilbert David , Tice David
Published: July 2021

Genetically engineered T cells have demonstrated great promise in the treatment of hematologic malignancies including Acute Lymphocytic Leukemia, Non-Hodgkin's lymphoma, and Multiple Myeloma. However, those achievements are often associated with uncontrolled toxicities, compromised T cell persistence, and frequent tumor relapse. Herein, we report a novel T cell therapy comprising a soluble tumor targeting protein (SPRX001) that specifically binds BCMA-expressing multiple myeloma cells and “TAGS” those cells for destruction by TAG-specific, ex vivo transduced T cells known as Antigen Receptor Complex (ARC) T cells. Functional in vitro studies of ARC-T cells produced from healthy subjects in combination with SPRX001 after co-culture with multiple BCMA-expressing cancer cell lines demonstrated dose-dependent cytokine production, T cell proliferation, degranulation and cytotoxic activity. The cytolytic machinery of the ARC-T cells is only activated when the tri-complex of the ARC-T cell, SPRX001, and BCMA-expressing cell is fully formed. In the absence of any one component, ARC-T cells are not activated thereby preventing kill of the intended target cells. ACLX-001 demonstrated dose- and schedule-dependent in vivo efficacy in disseminated BCMA-expressing tumor models in NSG immunocompromised mice. SPRX001 doses of 0.3 mg/kg daily or 3 mg/kg twice a week were able to eliminate measurable tumor burden as early as 7 days post dosing that lasted for the duration of the study. ARC-T cell expansion and contraction tracked tumor burden in vivo and displayed a diverse memory phenotype. The data support the paradigm that ARC-T cells can be activated and silenced by controlling the dose and schedule of administered SPRX001, which may improve the safety and effectiveness of T cell therapy.

Citation Format: Justin P. Edwards, Janine Buonato, David LaFleur, Jeffrey Swers, Jenny Mu, Liubov Zaritskaya, Sinnie Ng, Ankit Gupta, Hui Wang, Samantha McCullough, David Hilbert, David Tice. ACLX-001, a novel BCMA-targeted CAR-T cell therapy that can be activated, silenced, and reprogrammed in vivo with soluble protein adapters in a dose dependent manner [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 1549.
Abstract 155: A machine learning approach for accurate medulloblastoma subtyping using arm-level SCNAs
Authors: Yan Cheng , Wang Dan , Su Lan , Yang Yufei , Du Hao
Published: July 2021

Background: In 2010, scientific community reached a consensus regarding its subtyping (WNT/β-catenin, Sonic Hedgehog, Group 3, and Group 4). Research demonstrated that different subtype displays distinct genotypic characteristics as well as prognostics. Currently, transcriptomic profiling via NanoString is well-accepted for medulloblastoma subtyping. However, this platform requires high quality RNA sample. An alternative approach is in need for more robust and accurate subtyping. In this study, we explored the feasibility of using machine learning approach for medulloblastoma subtyping based on genome-wide SCNVs.

Method: We retrieved SNP array CEL data of 1097 medulloblastoma (GSE37385) from GEO. 800 samples were remained for further analysis after QC. 32 medulloblastoma samples were collected from Robinson G, et's study as independent validation set. Penncnv was used to calculate log R ratio and B allele frequency. DNAcopy was used for CNV segmentation. GISTIC2 was applied to obtain arm and focal SCNAs. A number of classifiers were trained using SCNAs as well as age and gender. Feature selection was conducted in a model specific manner. Model performance was assessed using AUROC.

Result: Benchmark on validation set showed that accuracy of Naïve Bayes, Random Forest, AdaBoost, Logistic Regression and SVM are 76.25%, 75%, 75%, 77.5% and 80.62% respectively. AUROC is 90.98%, 92.3%, 91.32%, 92.1% and 92.02% in corresponding order. The relatively overfitting and comparable performance across most models implied that SCNAs own moderate predictive power in medulloblastoma subtyping. Generally, SVM with linear kernel demonstrated superior and balanced performance than other models. Feature importance evaluation via Random Forest and AdaBoost showed better predictive power of arm-level SCNAa of 6p, 6q, 7p, 7q, 16q, 17p, 17q, consistently with previous studies. Focal SCNAs on SIRPB1 and age owned high predictive power. Nanostring performs poorly on distinguishing Group 3 and Group 4. Our method showed same tendency, indicating transcriptomic as well as genomic similarity between these two groups. We decided to permit 10% of validation samples as ‘prediction failure' for those with highly similar SCNAs characteristics. Upon this modification, accuracy of most model raised 3% on average.

Conclusion: Our study evaluated the feasibility of using genome-wide SCNAs profile for medulloblastoma subtyping. Benchmark showed moderate predictive power using SCNAs. Among a number of machine learning approaches, SVM with linear kernel demonstrated superior performance.

Citation Format: Cheng Yan, Dan Wang, Lan Su, Yufei Yang, Hao Du. A machine learning approach for accurate medulloblastoma subtyping using arm-level SCNAs [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 155.
Abstract 1558: Radiation therapy and immune checkpoint inhibitor combinations in the E0771 medullary breast adenocarcinoma
Authors: Fadden Patrick , Bui Thi , Davis Kelli , Hurtado David , Sugg Emily , Svancarek Abigail , Belle Ian , Hall Chassidy
Published: July 2021

Greater than 50% of all cancer patients receive radiation therapy at some point during their cancer treatment to control solid tumor growth (Harrington 2011). In addition to the direct action of radiation on tumor cell proliferation, radiation also has the potential to stimulate an anti-tumor immune response (Weichselbaum 2017). The success of immune checkpoint therapies such as anti-PD-1, anti-PD-L1, and anti-CTLA-4 inhibitory antibodies has driven large investment into the discovery of novel immune-oncology therapies. While the clinical response to immune checkpoint inhibitors can be profound for those patients that respond, there still exists a large percentage of patients that do not see benefit. In order to expand the number of patients that may respond to immune checkpoint inhibition, combination with radiation therapy needs to be tested and in fact a large number of preclinical and clinical studies are being conducted (for review see Asna 2019). Preclinical syngeneic tumor models are a critical means to assess new immunotherapies and drive preclinical programs. E0771 is a medullary breast adenocarcinoma cell line originally isolated from a spontaneous tumor and can be implanted subcutaneously in C57BL/6 mice (Ewens 2005). In order to characterize the E0771 syngeneic breast tumor model for future studies with radiation and immunotherapy, we assessed the efficacy changes in response to various schedules of radiation doses with and without either anti-PD-1 or anti-CTLA-4 antibody therapies. In addition, we analyzed the tumor infiltrating immune cell populations following radiation therapy. E0771 is sensitive to radiation therapy with a clear dose response. Radiation administered either as a single dose, hypofractionated, or hyperfractionated gave similar tumor responses. Flow cytometry analysis shows a higher infiltration of T regulatory cells compared with CD8+ T cells at baseline, which is exacerbated by irradiation. The CD8/Treg ratio is reversed with the addition of anti-CTLA-4 treatment to radiation and resulted in curative responses for 9 of 10 mice in the combination group.

Citation Format: Patrick Fadden, Thi Bui, Kelli Davis, David Hurtado, Emily Sugg, Abigail Svancarek, Ian Belle, Chassidy Hall. Radiation therapy and immune checkpoint inhibitor combinations in the E0771 medullary breast adenocarcinoma [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 1558.
Abstract 1563: DRP-104, a broad acting glutamine antagonist, synergizes with immune checkpoint blockade in vivo
Authors: Yokoyama Yumi , Wild Robert
Published: July 2021

We previously reported that DRP-104, a novel broad acting glutamine antagonist, has significant therapeutic potential in cancer by directly targeting tumor metabolism and simultaneously inducing a potent antitumor immune response. We also reported the immunomodulatory effect of DRP-104 on tumor growth inhibition (TGI) as a single agent and in combination with PD-1/PD-L1 checkpoint inhibitors in the MC38 and CT26 colon cancer syngeneic models(1). DRP-104 mediated TGI is associated with increased tumor-infiltrating leukocytes (TIL) including T, NKT, and NK cells; M1-polarized tumor associated macrophages; and decreased immune-suppressive cells such as MDSCs.Here we further elucidate the immunomodulatory effect of DRP-104 on tumor growth inhibition. In the MC38 mouse model, CD8+, CD4+, or NK cells were depleted by anti-CD8+Ab, anti-CD4+Ab, or anti-asialoGM1 Ab respectively to assess the contribution of these immune cells towards DRP-104 efficacy. CD8+T cell depletion significantly reduced anti-tumor efficacy for DRP-104 (73.9% TGI in CD8+T depletion setting vs 120% TGI with 57.8% regression in undepleted animals). NK cell depletion delayed early anti-tumor response to DRP-104 treatment, while in undepleted mice DRP-104 treatment showed TGI as early as 2 days after dose initiation. Interestingly, CD4+depleted mice showed enhanced efficacy to DRP-104 with TGI of 213% (regressions) and 6/8 tumor free mice 29 days after the end of treatment vs 1/8 mice tumor free in the CD4+ undepleted group with DRP-104 treatment. As such, we tested the combination of DRP-104 with anti-TIGIT antibody which has been reported to deplete Treg cells in the TME(2). In MC38 (anti-TIGIT insensitive) and CT26 (anti-TIGIT sensitive), DRP-104 showed significant single agent TGI. Furthermore, combination of DRP-104 with anti-TIGIT Ab demonstrated enhanced tumor growth inhibition and resulted in improvement in survival.

In summary, immune cell depletion experiments confirmed DRP-104's immuno-oncology mechanism of action. CD8+ or NK cell depletion reduced DRP-104 efficacy while CD4+ cell depletion enhanced efficacy. Furthermore, combination therapy of DRP-104 with anti-PD-1 or anti-TIGIT Ab achieved significantly enhanced anti-tumor efficacy even in checkpoint inhibitor resistant models. This unique and non-overlapping mechanism of action supports clinical development of DRP-104 alone and in combination with immune checkpoint inhibitors. The first in human clinical study of DRP-104 is ongoing.

References:

1.Yokoyama Y, Wild R. Abstract 5607: Cancer Research 2020;80:56072.Kurtulus S, Sakuishi K, Ngiow SF, Joller N, Tan DJ, Teng MW, et al. J Clin Invest 2015;125:4053-62

Citation Format: Yumi Yokoyama, Robert Wild. DRP-104, a broad acting glutamine antagonist, synergizes with immune checkpoint blockade 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 1563.
Abstract 1571: Neoantigen vaccine plus CD38 blockade suppress the proliferation of murine cold lung cancer LLC1
Authors: Sun Changbo , Nagaoka Koji , Hosoi Akihiro , Kobayashi Yukari , Nakajima Jun , Kakimi Kazuhiro
Published: July 2021

Immune checkpoint inhibitors are now the mainstay for the treatment of lung cancer. However, so-called cold tumors are known to be resistant to checkpoint inhibitors. Neoantigens associated with genetic mutations of the tumor have the potential to stimulate a potent and highly specific immune response. To develop effective immunotherapy for cold lung cancer, we examined whether neoantigen-based immunotherapy can develop immune responses and display anti-tumor effects on the cold lung cancer model, Lewis lung carcinoma cells (LLC1) resistant to anti-CTLA-4 or anti-PD-1 therapy.

LLC1 cells were subjected to whole-exome and RNA sequencing. Mutation-associated neoantigens were predicted and prioritized by their affinity to MHC class I molecules and their expression. Using netMHCpan, sixty mutated peptides with IC50 <200 nM and 68 mutated peptides with IC50>200 nM, but the wild to corresponding mutated peptide ratio of binding affinity>10 were selected as candidate neoantigens. C57BL/6 mice were immunized with dendritic cells pulsed with these neoantigen short peptides (8-10mer). Twenty-five out of 128 short mutated peptides induced peptide-specific CD8+ T cell response to some extent. Next, 25 long peptides (21mer), which incorporated corresponding immunogenic short peptide sequences, were synthesized and used to immunize mice. DC vaccines pulsed with neoantigen in long peptide format (LP) induced both CD4+ and CD8+ T cell response ex vivo. Of them, DC pulsed with LP82 partly delayed the LLC1 growth in vivo.

By RNA-Seq, CD38 was highly expressed in LLC1. Thereby, an anti-CD38 antibody was administered in LLC1-bearing mice immunized with DC pulsed with LP82. The tumor growth was suppressed in the combination treatment. Although CD38 plays an important role in converting nicotinamide adenine dinucleotide (NAD+) to adenosine, adenosine receptor antagonist could not inhibit the tumor growth in mice immunized with LP82. Alternatively, NAD+ accumulation due to CD38 blockade decreased regulatory T cells in the tumor immune microenvironment, consistent with the decreased Foxp3+ transcription and increased IFNg and IL2 production of CD4+ T cells sorted from tumor immune microenvironment.

Our study suggested that the prioritization of neoantigens that can induce anti-tumor response is critical for developing neoantigen-targeting immunotherapy. Combining an effective neoantigen vaccine and precise immune modulator could enhance anti-tumor activities even in cold lung tumors.

Citation Format: Changbo Sun, Koji Nagaoka, Akihiro Hosoi, Yukari Kobayashi, Jun Nakajima, Kazuhiro Kakimi. Neoantigen vaccine plus CD38 blockade suppress the proliferation of murine cold lung cancer LLC1 [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 1571.
Abstract 1577: Caloric restriction mimetics as adjuvant to immune checkpoint inhibitors for treatment of melanoma
Authors: Morehead Lauren C. , Koss Brian S. , Wallis Katherine F. , Tackett Alan J. , Miousse Isabelle Racine
Published: July 2021

Immune checkpoint inhibitors (ICIs) have revolutionized melanoma therapy. Still, the 5-year survival for advanced melanoma is only 50%. This leads to two questions: what makes some tumors less responsive to ICIs, and what can be done to increase responsiveness? Prior research suggests that hypoxia in the tumor microenvironment (TME) decreases the efficacy of ICIs, and metformin, an antihyperglycemic and caloric restriction mimetic (CRM), is able to reverse this condition. We hypothesize that other CRMs will also increase responsiveness to ICIs through hypoxia, and potentially other mechanisms. We chose three CRMs to study alongside metformin: hydroxycitrate, resveratrol, and sulforaphane. To identify pathways and understand more about CRMs effect on tumor hypoxia, we performed a proteomics experiment on B16F10 murine melanoma cells treated with all four CRMs. Proteomics analysis was done with a tandem mass tag labeling. To determine effect of caloric restriction mimetics on immunotherapy efficacy, B16F10 cells will be injected subcutaneously in immunocompetent male and female C57BL/6J mice, separated into four groups: 1) no treatment control, 2) ICI therapy only, 3) CRM therapy only, 4) ICI + CRM combination.

Our preliminary data shows that, like metformin, additional CRMs decrease oxidative phosphorylation in cancer cells. This supports the hypothesis that the other CRMs may function similarly to metformin in the TME. We started testing the effect of four CRMs on tumor growth and hypoxia in an animal model. Our ultimate goal is to improve responsiveness to immune checkpoint inhibitors in patients with metastatic melanoma.

Citation Format: Lauren C. Morehead, Brian S. Koss, Katherine F. Wallis, Alan J. Tackett, Isabelle Racine Miousse. Caloric restriction mimetics as adjuvant to immune checkpoint inhibitors for treatment of melanoma [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 1577.
Abstract 1579: Oncolytic adenovirus Delta-24-RGDOX collaborates with adoptive cell therapy to sustain anti-tumor immunity
Authors: Jiang Hong , Nguyen Teresa T. , Shin Dong Ho , Sohoni Sagar S. , Gupta Sumit , Yi Yanhua , Fan Xuejun , Gomez-Manzano Candelaria , Fueyo Juan
Published: July 2021

Oncolytic virotherapy and adoptive T cell therapy (ACT) are promising strategies for cancer treatment, but both are underdeveloped into routine clinical interventions for solid tumors. We reported previously that localized treatment with oncolytic adenovirus Delta-24-RGDOX (DNX-2440), which expresses immune co-stimulator OX40 ligand, stimulated tumor-specific T cells proliferation and migration to untreated disseminated tumors. We hypothesize that intratumorally injected Delta-24-RGDOX complements with ACT to overcome antigen escape, leading to more sustainable anti-cancer effect. To test the hypothesis, we used B16-OVA-C57BL/6 subcutaneous (s.c.)/s.c. melanoma model to assess the effect of the combination therapy. Briefly, 10 days after the first tumor implantation, we injected OVA-specific CD8+ T cells from OT-I mice into the first tumor, followed by three injections of Delta-24-RGDOX into the same tumor. We found the combination was more potent to inhibit the injected 1st tumor and untreated disseminated 2nd tumor growth and resulted in improved survival rate than either of the agent alone (p less than 0.05). Interestingly, we observed relapse of the regressed tumors in the group treated by T cells alone, which recapitulated the effect of CAR T therapy in cancer patients. But the relapse was not observed in most of the mice from the combination group, indicating the combination induces more sustainable tumor regression than T cells alone. The survivors from the combination therapy were protected from rechallenging with B16-OVA cells but not lung carcinoma cells, suggesting the development of immune memory against the same tumor cells. Furthermore, profiling the tumor-infiltrating lymphocytes with flow cytometry revealed that the combination promotes the T cell presence within the tumor and increase the population of the T cells targeting other antigens in addition to the original ACT targeted antigen. Collectively, the results demonstrate that Delta-24-RGDOX collaborates with ACT to induce more potent systemic immunity against the tumors, leading to more sustainable tumor regression and improved survival rate. Our study suggests the virus induces antigen spread, resulting in T cell repertoire to target more tumor-associated antigens to overcome cancer relapse due to cancer heterogeneity and limited targets in ACT and CAR T therapy.

Citation Format: Hong Jiang, Teresa T. Nguyen, Dong Ho Shin, Sagar S. Sohoni, Sumit Gupta, Yanhua Yi, Xuejun Fan, Candelaria Gomez-Manzano, Juan Fueyo. Oncolytic adenovirus Delta-24-RGDOX collaborates with adoptive cell therapy to sustain anti-tumor immunity [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 1579.
Abstract 1581: Nammisomes: Preclinical validation of a platform for selective and synchronized delivery of novel immunotherapy prodrug combinations to tumors
Authors: Stover David R. , Bharali Dhruba , Safaie Tahmineh , Hay Bruce A. , Sharma Rajesh K. , Ayers Scott
Published: July 2021

The approval of checkpoint inhibitors, CAR-T cell therapies, and other immunotherapies has led to a significant improvement in cancer patient survival rates over the past 7 years. However, the pace of improvement has slowed lately as the field moves beyond the minority of patients with immune primed or accessible cancers. It is generally expected that rationale combinations of immunotherapies that provide mechanisms to both induce as well as maintain the immune responses in the face of tumor-derived immune checkpoint mediators, will be required to effectively treat these patients. Systemic exposure to such combinations often can give rise to severe toxicity profiles that limit their therapeutic efficacy. Nammisomes are an innovative and unique platform designed to deliver novel immune modulating prodrugs more selectively and synchronously to the tumor site. The immune active agents are conjugated to lipids to create prodrugs that self-assemble into a liposomal bilayer. By mixing multiple prodrugs at the desired ratio, co-formulations are produced with the optimum stoichiometry. These Nammisomes are iv injected and selectively enter tumors through the leaky vasculature within tumors, while remaining in circulation in normal tissues with intact blood vessels, The enriched phagocytic activity in tumor environments causes the release of the active agents within tumors relative to normal tissues limiting systemic exposure and toxicities. Preclinical efficacy and safety data of Nammisomes delivering combinations of a TLR agonist and a checkpoint inhibitor showing anti-tumor efficacy and tolerability in syngeneic mouse models will be presented. In summary, Nammisomes will be highlighted as a combination therapeutic modality to demonstrate the potential of this approach in anti-cancer therapy.

Citation Format: David R. Stover, Dhruba Bharali, Tahmineh Safaie, Bruce A. Hay, Rajesh K. Sharma, Scott Ayers. Nammisomes: Preclinical validation of a platform for selective and synchronized delivery of novel immunotherapy prodrug combinations to 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 1581.
Abstract 1599: SMARCA4 regulates tumor resistance to anti-tumor immune response
Authors: Chaudhri Apoorvi , Wang Yunfei , Shi Leilei , Rai Kunal , Hwu Patrick
Published: July 2021

Chromatin remodelers regulate chromatin accessibility and translocation of the nucleosome to expose the underlying DNA sequence. SWI/SNF is a conserved chromatin remodeling complex required for transcriptional activation or repression. In fact, SWI/SNF is the most frequently mutated chromatin regulator in cancer. Though the general understanding is that subunits of the SWI/SNF complex mainly act as tumor suppressors, studies have shown that they can have a context-dependent oncogenic role. Moreover, the PBAF subunits of the complex, PBRM1 and ARID2 impart immunoresistance in B16 melanoma tumors. We perform a TCGA analysis of the subunits based on expression and see that high PBRM1 or SMARCA4 expression in SKCM melanoma correlates with lower survival. Interestingly, SMARCA4 is the conserved catalytic subunit of the complex, and is essential to hydrolyze the energy of the ATP to execute the remodeling function of the complex. On performing a knockdown of SMARCA4 in an in vitro model of B16 cells, a co-culture with antigen specific T cells shows an increase in T cell cytotoxicity. Furthermore, RNA sequencing reveals that knockdown of SMARCA4 upregulates the genes associated with interferon response and downregulates MYC targets. We show that SMARCA4 may mediate immunoresistance such that a knockdown of SMARCA4 in the tumor will sensitize it to anti-tumor immunity. We will next take an in vivo approach to examine if SMARCA4 knockdown will enhance the tumor immune response via an interferon related mechanism.

Citation Format: Apoorvi Chaudhri, Yunfei Wang, Leilei Shi, Kunal Rai, Patrick Hwu. SMARCA4 regulates tumor resistance to anti-tumor immune response [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 1599.