bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 3895: Moxidectin unravels the role of Hippo-YAP pathway in maintaining immunity of pediatric glioblastoma
Authors: Kaushik Itishree , Gaikwad Shreyas , Srivastava Sanjay K.
Published: June 2022

Pediatric glioblastoma multiforme (GBM) is considered to be the second most lethal childhood cancer type after leukemia. Recent preclinical, clinical and genomic studies have highlighted upon the role of Hippo-Yap pathway in the progression of pediatric GBM. In addition, recent studies have established the role of YAP in creating immune suppressive tumor microenvironment (TME) facilitating drug resistance, recurrence and metastasis of GBM tumors. Herein, we report that ‘moxidectin’ an anti-helminthic drug inhibits the proliferation of SF268, SF295, SF188 and CT-2A Luc GBM cells by inducing apoptosis. Immunoblotting and immunofluorescence microscopy studies show that moxidectin mediates its effects by inhibiting MEK-ERK pathway, a regulator of Hippo-YAP signaling. As a result, moxidectin suppressed the nuclear translocation and transcriptional activity of YAP/TAZ-TEAD complex. Oral administration of 3.5mg/kg moxidectin suppressed the growth of GBM tumors by 90% in intracranial tumor model. Ex-vivo analysis of excised tumors confirmed the observations made in in vitro studies. We further conducted immunophenotyping on the excised tumors from both control and moxidectin treated mice to evaluate the effect of moxidectin on immune cell markers in TME and Tumor Draining Lymph Nodes (TDLNs). Our analysis indicated that treatment with moxidectin suppressed the immune suppressive TME created by GBM tumor. Interestingly, moxidectin enhanced antigen presentation in the TDLN. Indicating that it might play a role in activating the peripheral immune response. Moxidectin is an FDA approved drug and any findings from our research will promote its further investigation as a potential therapeutic agent for GBM patients.

Citation Format: Itishree Kaushik, Shreyas Gaikwad, Sanjay K. Srivastava. Moxidectin unravels the role of Hippo-YAP pathway in maintaining immunity of pediatric glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3895.
Abstract 3941: TNG908 is an MTAPnull-selective PRMT5 inhibitor that drives tumor regressions in MTAP-deleted xenograft models across multiple histologies
Authors: Briggs Kimberly J. , Cottrell Kevin M. , Tonini Matthew R. , Wilker Erik W. , Gu Lina , Davis Charles B. , Zhang Minjie , Whittington Doug , Gotur Deepali , Goldstein Matthew J. , DiBenedetto Heather , Rudoltz Marc S. , Huang Alan , Maxwell John P.
Published: June 2022

TNG908 is an investigational PRMT5 inhibitor with a novel MTA-cooperative binding mechanism designed to leverage the synthetic lethal interaction between PRMT5 inhibition and MTAP deletion. MTAP deletion occurs in 10-15% of all human cancer representing multiple histologies. MTA is a negative regulator of PRMT5 that accumulates as a result of MTAP deletion. TNG908 selectively binds the PRMT5-MTA complex driving selective inhibition of PRMT5 in MTAP-null cancers, which is postulated to create a large therapeutic index relative to PRMT5 inhibitors currently in clinical development. TNG908 is 15X selective for MTAPnull cell lines over isogenic MTAPWT cell lines, and has marked selectivity for MTAP-deleted cancer cell lines independent of lineage in a large, diverse cell line panel. In vitro mechanistic studies confirm that MTAPnull-selective PRMT5 inhibitors can selectively target MTAPnull cancer cells in either an admixture of MTAPnull and MTAPWT cells, or with intracellular MTA accumulation 2-5X relative to basal levels in MTAPWT cells. Oral administration of TNG908 drives dose-dependent, MTAPnull-selective antitumor activity in multiple xenograft models, including tumor regressions in models representing non-small cell lung cancer (adenocarcinoma and squamous), cholangiocarcinoma, urothelial carcinoma, and others. Preclinical studies suggest clinical combinations that leverage PRMT5 biology and/or concurrent oncogenic driver mutations, such as KRASG12C. In summary, TNG908 is a novel, potent PRMT5 inhibitor with excellent drug-like properties and strong preclinical activity in multiple xenograft models that has the potential for histology-agnostic clinical development in MTAP-deleted solid tumors.

Citation Format: Kimberly J. Briggs, Kevin M. Cottrell, Matthew R. Tonini, Erik W. Wilker, Lina Gu, Charles B. Davis, Minjie Zhang, Doug Whittington, Deepali Gotur, Matthew J. Goldstein, Heather DiBenedetto, Marc S. Rudoltz, Alan Huang, John P. Maxwell. TNG908 is an MTAPnull-selective PRMT5 inhibitor that drives tumor regressions in MTAP-deleted xenograft models across multiple histologies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3941.
Abstract 3982: Molecular mechanism of cisplatin-induced p53 activation, cell cycle regulation, and apoptosis in acute leukemia cells
Authors: Tchounwou Paul B. , Kumar Sanjay
Published: June 2022

Cisplatin (CDDP) is an anticancer drug successfully used in the treatment of various human malignancies. Although it has been shown to enhance the potency of arsenic trioxide in chronic myelogenous leukemia (CML) cells and to induce cytotoxicity in acute promyelocytic leukemia (APL) cell lines, its molecular mechanism of action is mostly unknown. We investigated a novel mode of action of CDDP through modulation of stress signals, disruption of MDM2-DAXX-HAUSP complex, and activation of p53 in APL cell lines. We found that CDDP-induced stress signals were transmitted and reduced expression of complex molecules and also effected their association leading to p53 activation. CDDP-activated p53 led to cell cycle arrest and induced both early and late apoptosis in APL cells. Our findings also showed that CDDP stimulated more promyelocytes formation with dense granules, activated p53 expression, and reduced expression of MDM2 in both APL mice bone marrow cells and liver tissues. This novel mechanism of action of CDDP in APL cells may help in the design of new anti-leukemic drugs for treatment of APL patients.

Citation Format: Paul B. Tchounwou, Sanjay Kumar. Molecular mechanism of cisplatin-induced p53 activation, cell cycle regulation, and apoptosis in acute leukemia cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3982.
Abstract 4015: Primary sites affecting the prognosis of Ewing's sarcoma
Authors: Mao Jun-Qing , Zhao Dan
Published: June 2022

Introduction Ewing’s sarcoma (ES) is a small round blue cell malignancy arising from the bone or soft tissue, and most commonly impacts adolescents and young adults. It is difficult to identify those who will likely relapse, however, ES has a very high recurrence rate. Given these realities, the objective of this study was to determine factors influencing the prognosis of ES patients.

Methods Clinical and genomic data of 99 patients with ES, were obtained from the cBioPortal. Tumor mutational burden (TMB) and patient survival information were also obtained from the cBioPortal.

Results In the data examined, ES had multiple primary sites of disease, including 16 femur, 10 hipbone, 10 rib, 10 tibia, 6 ischium pubis, 5 scapula, 4 fibula, 3 dorsal vertebra, 3 intra-abdominal, 3 lumbar vertebra, and 3 skull. A comparison of survival relationships between different primary sites of ES indicated that overall survival (OS) was significantly different between femur and dorsal vertebra (p = 0.023) and intra-abdominal and hipbone (p = 0.049). However, no significant difference was determined for TMB between the different primary sites. The median value of TMB was 0.23. Data were divided into two groups: high TMB (TMB-H,≥ 0.23 muts/Mb) and low TMB (TMB-L, < 0.23muts/Mb). Interestingly, the OS of patients with TMB-L was significantly higher than that of patients with TMB-H (p = 0.049; 59.45 versus 42.00 months). The presence of metastases at the time of diagnosis was associated with poor OS ( p = 0.023;) and was a clinical factor associated with outcomes having statistical significance.

Conclusions Given the heterogeneity in outcomes for patients with ES, additional prognostic factors are needed to optimize clinical decision making. Prognosis was different depending on primary site of ES. Patients with ES in hipbone displayed a better prognosis compared to that in abdomen. Similarly, patients with ES in dorsal vertebra had a significantly higher OS than that in femur. As such, the primary site should perhaps be considered during ES treatment, although there was no significant difference between TMB and primary site. Our results indicate that high TMB is associated with inferior survival for ES and may provide insights for clinical practice.

Citation Format: Jun-Qing Mao, Dan Zhao. Primary sites affecting the prognosis of Ewing's sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4015.
Abstract 4059: Design and in vitro antitumor analysis of a novel diphenyltin complex (diphenyltin dioxalate)
Authors: Witter Jade , Song Xuequing , Taraboletti Alexandra , Li William , Henry Tajera
Published: June 2022

Organotins are popular among chemists due to their potential biological properties against bacteria, fungus, and cancer cell lines. In particular, organotins have been utilized in chemotherapeutic applications. Compared to cisplatin, organotins give more favorable toxicological profiles and better cytotoxicity and antiproliferative activities. However, organotins have limited biological applications due to their poor water solubility. In this study we synthesized a diphenyltin complex (Diphenyltin Dioxalate) that possesses partial ionic characteristics, by reacting a diprotic carboxylic acid, with triphenyltin chloride in the presence of di-isopropylamine. A tin-carbon cleavage reaction was observed, as IR/NMR spectroscopy and X-ray Crystallography studies showed that diphenyltin dioxalate was successfully obtained in the reaction. Post synthesis solubility tests were performed to examine diphenyltin dioxalate’s water-soluble nature, compared to its precursor triphenyltin. Diphenyltin dioxalate was then tested to examine its cytotoxicity and antitumor activity on human glioblastoma cell model (T98G) and a normal human oligodendrocyte cell model (MO3.13). Further studies with the complex will consist of synthetic mechanistic studies on the Sn-C cleavage.

Citation Format: Jade Witter, Xuequing Song, Alexandra Taraboletti, William Li, Tajera Henry. Design and in vitro antitumor analysis of a novel diphenyltin complex (diphenyltin dioxalate) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4059.
Abstract 406: Mechanism of AXL regulation in chemotherapy resistance
Authors: Ahmed Mehreen , Kazi Julhash Uddin
Published: June 2022

Constitutive activation of receptor tyrosine kinase AXL is an important phenomenon in chemotherapy resistance and is highly expressed in several malignancies. Although studies over the past decade revealed that AXL is upregulated during treatment, the biological significance and the mechanism by which AXL is activated upon chemotherapy are yet to be determined. In this study, we aim to understand the biology of AXL mediated chemo-resistance, and the consequences of AXL activation. To investigate the biological significance of AXL, we generated iRFP-luciferase-expressing cell lines which facilitate live monitoring of cancer progression during treatment in an in vivo setting. In parallel, by knocking down AXL using shRNA, we observed inhibitory effect on cell migration and tumor forming efficiency in vitro. Moreover, using in vitro cell based models, we showed that while AXL expression was upregulated upon treatment with chemotherapeutic agents, pharmacological inhibition of AXL caused synergistic effect between selective AXL inhibitors and cisplatin. Additionally, our data suggest that upregulation of AXL and its tyrosine phosphorylation may mediate resistance to chemotherapy. Using phosphoproteomics, we identified a link between CDK9 activation and drug-induced AXL expression. We showed that while AXL expression was upregulated upon treatment with tyrosine kinase inhibitor, pharmacological inhibition of CDK9 completely blocked AXL expression. Collectively, our data suggest that activation of kinase signaling might be required for AXL repression, and thereby, for targeting AXL-axis in chemotherapy resistance.

Citation Format: Mehreen Ahmed, Julhash Uddin Kazi. Mechanism of AXL regulation in chemotherapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 406.
Abstract 4096: Development of novel anticancer RNA therapeutics with dual-targeting siRNA that silences ubiquitin family members
Authors: Azorsa David O. , Lee David W. , O'Ketch Marvin , Azorsa Nathalie A. , Papacharalampous Ioanna , Castaño Lizette A. , Kiefer Jeffrey A. , Mousses Spyro
Published: June 2022

Ubiquitination is a metabolic process in eukaryotic cells that modifies proteins with ubiquitin leading to protein degradation via the ubiquitin-proteosome pathway. Cellular levels of ubiquitin are driven by the expression of RPS27A, UBA52, UBB and UBC. In cancer, the dysregulation of ubiquitination can affect various aspects of tumor progression including cell cycle regulation and gene expression. Ubiquitin B (UBB) gene has been shown to be over-expressed in some tumor types, including NSCLC and cervical cancer, and under-expressed in other tumors, in particularly a subset of ovarian cancers. A role for ubiquitin C (UBC) in cancer has not been well established but UBC has been described as a biomarker in renal cancer and CLL. In recent studies, repression of UBB in ovarian cancer cells was associated with sensitivity to UBC knockdown and demonstrated a synthetic lethal relationship. Since both UBB and UBC show substantial sequence homology, we explored the possibility of developing dual targeting siRNA that would silence both UBB and UBC. We identified unique individual siRNA sequences that efficiently silenced both UBB and UBC and led to rapid cytotoxicity in several cancer cell lines including the colon cancer cell line HCT-116, the breast cancer cell line SK-BR3, and the prostate cancer cell line 22Rv1. Treatment with either UBB-specific or UBC-specific siRNA did not show the same lethal phenotype. Dose response assays using the dual targeting siRNA designated U21 indicated EC50 for cytotoxicity between 50–500 pM in several cancer lines. Treatment of cancer cell lines with U21 leads to rapid apoptosis and cell death. Chemical modifications to pharmacologically stabilize the U21 siRNA sequence did not change its activity. The efficient cytotoxic activity of the U21 siRNA sequence has been integrated into our SeekR™ platform to create aptamer-siRNA chimeras for targeted delivery of the lethal U21 payload to specific cancer cell types.

Citation Format: David O. Azorsa, David W. Lee, Marvin O'Ketch, Nathalie A. Azorsa, Ioanna Papacharalampous, Lizette A. Castaño, Jeffrey A. Kiefer, Spyro Mousses. Development of novel anticancer RNA therapeutics with dual-targeting siRNA that silences ubiquitin family members [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4096.
Abstract 4145: Novel approach that combines an automated breast cancer grading platform with genomics to personalize risk assessment and management
Authors: Donovan Michael J.
Published: June 2022

Background: The role of histopathology including stage, tumor size and histologic grade in defining breast cancer (BCA) clinical risk assignment continues to be an important component of treatment choice and management. Recent publications have demonstrated the significance of combining these features with genomic signatures such as Oncotype and EndoPredict to provide precision risk assessment. Unfortunately, intra-inter pathologist BCA grading variability remains a significant limiting factor.

Methods: Using the Cancer Genome Atlas (TCGA) breast cancer (BCA) image dataset, clinical and genomic data (i.e., EndoPredict and Oncotype), we evaluated a series of H&E images from patients with infiltrating ductal BCA (one slide per patient). A machine-learning (ML) derived morphology feature array was used to normalize staining differences, identify regions of tumor vs. normal and characterize individual cellular attributes including tubule structure and organization, nuclear morphology, and mitotic figures. Individual features were correlated with overall survival using the concordance index (c-index), support vector models and Kaplan-Meier incidence curves to understand feature importance.

Results: ML curated image features representing BCA gland morphology were generated from 517 patients with 69 events (13%), 93% overall survival (OS), median 5-years. Three clinical variables including: age, 59 years (median), AJCC stage T2 and 49% grade 3 and 41% grade 2, along with results of the EndoPredict (EP) and an Onctoype (ONC) gene subset: PGR, ESR1, CCNB1, BIRC5, MYBL2, GRB7) and imaging features were evaluated. Only age, stage and 10 imaging features representing nuclear shape, size, mitotic activity, lymphoid aggregates and stromal content were selected. Two models consisting of clinical + gene expression + imaging produced a C-index of: 0.84 (EP) vs. 0.82 (ONC), respectively, vs. clinical (0.79) and clinical + genomics ( EP 0.81vs. ONC 0.79).

Conclusions: A machine-learning platform outperformed grade and produced accurate recurrence risk models with demonstrated added improvement over clinical and genomic analyses. Future studies include expanded cohort studies to confirm and expand these observations.

Citation Format: Michael J. Donovan. Novel approach that combines an automated breast cancer grading platform with genomics to personalize risk assessment and management [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4145.
Abstract 4170: Integrative transcriptomic and proteomic analysis reveals immunogenic and spatially-conserved HLA-binding neoantigen targets derived from tumor-specific alternative splicing events
Authors: Kwok Darwin , Nejo Takahide , Du Aidan , Colton Maggie , Woo James , Costello Joseph , Okada Hideho
Published: June 2022

BACKGROUND: While immunotherapy is profoundly efficacious in certain cancers, its success is limited in cancers with lower mutational burden, such as gliomas. Therefore, investigating neoantigens beyond those from somatic mutations can expand the repertoire of immunotherapy targets. Recent studies detected alternative-splicing (AS) events in various cancer types that could potentially translate into tumor-specific proteins. Our study investigates AS within glioma to identify novel MHC-I-presented neoantigen targets through an integrative transcriptomic and proteomic computational pipeline, complemented by an extensive spatiotemporal analysis of the AS candidates.

METHODS: Bulk RNA-seq of high tumor purity TCGA-GBM/LGG (n=429) were analyzed through a novel systematic pipeline, and tumor-specific splicing junctions (neojunctions) were identified in silico by cross-referencing with bulk RNA-seq of GTEx normal tissue (n=9,166). Two HLA-binding prediction algorithms were subsequently incorporated to predict peptide sequences with high likelihood for HLA-presentation. Investigation of the tumor-wide clonality and temporal stability of the candidates was performed on extensive RNA-seq data from our spatially mapped intratumoral samples and longitudinally collected tumor tissue RNA-seq. Proteomic validation was conducted through mass-spec analysis of the Clinical Proteomic Tumor Analysis Consortium (CPTAC)-GBM repository (n=99).

RESULTS: Our analysis of TCGA-GBM/LGG bulk RNA-seq identified 249 putative neojunctions that translate into 222 cancer-specific peptide sequences which confer 21,489 tumor-specific n-mers (8-11 amino acids in length). Both prediction algorithms concurrently identified 271 n-mers likely to bind and be presented by HLA*A0101, HLA*A0201, HLA*A0301, HLA*A1101, or HLA*A2402. We confirmed the expression of 15 out of 58 HLA*A0201-binding candidates in RNA-seq of two HLA*A0201+ patient-derived glioma cell lines with a subset of candidates found tumor-wide. Analysis of CPTAC-GBM mass-spec data detected 23 tumor-specific peptides with 5 containing detected n-mers highly predicted to be HLA-presented.

CONCLUSION: Tumor-specific neojunctions identified in our unique integrative pipeline present novel candidate immunotherapy targets for gliomas and offer a new avenue in neoantigen discovery across cancer types.

Citation Format: Darwin Kwok, Takahide Nejo, Aidan Du, Maggie Colton, James Woo, Joseph Costello, Hideho Okada. Integrative transcriptomic and proteomic analysis reveals immunogenic and spatially-conserved HLA-binding neoantigen targets derived from tumor-specific alternative splicing events [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4170.
Abstract 4178: PAK4 inhibition improves PD1 blockade immunotherapy in prostate cancer
Authors: Su Shengchen , You Sungyong , Wang Yanping , Tamukong Patrick , Grasso Catherine S. , Kim Hyung L.
Published: June 2022

Prostate cancers have low immune infiltration and do not respond to PD1 blockade immunotherapy. The objective of this study was to examine the effect of PAK4 inhibition on anti-tumor immune response in preclinical prostate cancer models. C57BL/6J mice (male, 5-8 weeks old) were injected with wild type (WT) or PAK4 knockdown (KD) syngeneic Rm1 tumor cells (2X105 cell/mouse) and treated with or without αPD1 blockade (200μg, BioXCell). Tumor growth was monitored and analyzed using ANOVA of repeated measures (n=6). In a separate experiment, 1 cm RM1 tumors were collected for RNA sequencing (RNASeq) and immunohistochemistry (IHC). RNASeq data were normalized using the variance stabilizing transformation (VST) function as implemented within the DESeq2 package. IHC images were captured with Keyence BZ-X800 and positive staining was calculated using ImageJ. CD8+ lymphocytes depletion was achieved by CD8 antibody injection (200ug, BioXCell). PAK4 inhibitors PF-3758309 (PF) and KPT-9274 (KPT) were evaluated in murine models. PAK4 KD tumors treated with αPD1 antibody (αPD1) showed a significant reduction of tumor growth when compared to growth in WT (P<.05), WT αPD1 (P<.01), and KD (p<.05). Analysis of bulk tumor RNAseq showed that the combination of PAK4 KD with αPD1 was associated with increased CD8a, IFNγ, and PD-L1 expression. IHC with αCD8 verified that PAK4 KD increased CD8+ cell infiltration in mouse tumors. Further, RNAseq showed that PAK4 KD increased the expression of cytokines, chemokines, and genes related to the IFNγ response. These results suggest that PAK4 KD primes the tumor for immune infiltration and improves αPD1 treatment response. The anti-tumor effect of PAK4 KD with αPD1 in mice was CD8-dependent and could be eliminated by CD8+ cell depletion (p<.05). We tested two different PAK4 inhibitors in mice with WT Rm1 tumors. PF is a kinase inhibitor that blocks the function of PAK4. A combination of PF and αPD1 significantly reduced tumor growth when compared to WT (P<.05), WT αPD1 (P<.01), and PF (p<.05). KPT is a dual inhibitor of PAK4 and NAMPT, which reduces the cytosolic protein concentration of PAK4. A combination of KPT and αPD1 significantly reduced tumor growth when compared to WT (P<.01) and WT αPD1 (P<.01). In conclusion, PAK4 inhibition increased immune infiltration and improved αPD1 treatment response in preclinical mouse prostate cancer models.

Citation Format: Shengchen Su, Sungyong You, Yanping Wang, Patrick Tamukong, Catherine S. Grasso, Hyung L. Kim. PAK4 inhibition improves PD1 blockade immunotherapy in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4178.
Abstract 4216: Tipifarnib inhibits the secretion of tumor-derived small extracellular vesicles and enhances the immunotherapeutic efficacy of dinutuximab in neuroblastoma
Authors: Liu Xiaoming , Wills Carson A. , Chen Longgui , Zhang Jiawen , Zhao Yuanjun , Zhou Mi , Sundstrom Jeffrey M. , Schell Todd D. , Spiegelman Vladimir S. , Young Megan M. , Wang Hong-Gang
Published: June 2022

Anti-GD2 monoclonal antibody (Dinutuximab) immunotherapy has significantly improved the overall survival rate for high-risk neuroblastoma patients. However, 40% of patients fail to respond or develop resistance to the treatment, and the molecular mechanisms by which this occurs remain poorly understood. Here we utilize the syngeneic 9464D-GD2 mouse model to investigate the role of neuroblastoma tumor-derived small extracellular vesicles (sEVs) in developing resistance to the anti-GD2 monoclonal antibody Dinutuximab. Neuroblastoma-derived sEVs significantly attenuated the efficacy of Dinutuximab treatment in vivo. Mechanistically, both RNA-sequencing and flow cytometry analysis of whole tumors demonstrated that neuroblastoma-derived sEVs modulate immune cells tumor infiltration upon Dinutuximab treatment to create an immunosuppressive tumor microenvironment, which contains more tumor-associated macrophages (TAMs) and fewer tumor-infiltrating NK cells, in addition to suppression of splenic NK cell maturation in vivo. Moreover, neuroblastoma-derived sEVs suppressed Dinutuximab-mediated NK cell antibody-dependent cellular cytotoxicity in vitro. Importantly, Tipifarnib, a farnesyltransferase inhibitor that inhibits sEV secretion, drastically enhanced the efficacy of Dinutuximab in vivo and reversed the immunosuppressive effects of neuroblastoma-derived sEVs. Notably, Tipifarnib modulated immature myeloid cells in the bone marrow to disfavor the formation of CD11b+Ly6ChighLy6Glow subpopulations, which are the precursors for TAMs. Taken together, these preclinical findings uncover a novel mechanism by which neuroblastoma-derived sEVs modulate the immune system to promote resistance to Dinutuximab and suggest that Tipifarnib-mediated inhibition of sEV secretion may serve as a viable treatment strategy to improve immunotherapy in high-risk patients.

Citation Format: Xiaoming Liu, Carson A. Wills, Longgui Chen, Jiawen Zhang, Yuanjun Zhao, Mi Zhou, Jeffrey M. Sundstrom, Todd D. Schell, Vladimir S. Spiegelman, Megan M. Young, Hong-Gang Wang. Tipifarnib inhibits the secretion of tumor-derived small extracellular vesicles and enhances the immunotherapeutic efficacy of dinutuximab in neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4216.
Abstract 4235: PPRX-1701, a deliverable nanoparticle formulation of 6-bromo-acetoxime, blocks tumoral IDO1 expression and shows efficacy in immunocompetent murine glioblastoma models
Authors: Zdioruk Mykola , Nowicki Michal , Wu Bin , Boucher Paul , Takeda Yuji , Li Weiyi , Chiocca E Antonio , Lawler Sean E.
Published: June 2022

Introduction: We previously showed that derivatives of the Chinese traditional medicine indirubin promote survival in murine models of the brain tumor glioblastoma. However, poor drug solubility hampered further development of this approach. Here we introduce PPRX-1701, a 6’-bromoindirubin acetoxime (BiA) containing drug/polymer nanoparticle formulation which can be injected intravenously at relatively high concentrations. Here we examine the efficacy and mechanism of PPRX-1701 in murine glioblastoma models.

Methods: In vitro glioblastoma cell proliferation and migration assays were performed using standard approaches. Effects of PPRX-1701 on interferon-γ (IFN γ) signaling were determined by Western blotting. Delivery to murine GBM was assessed using a luminescent reporter assay, and survival studies were performed in immunocompetent murine glioblastoma models.

Results: PPRX-1701 effects on glioblastoma cell proliferation and migration were indistinguishable from BiA alone. Our data show that intravenous administration of PPRX-1701 is well-tolerated and can reach intracranial murine glioblastoma as assessed by luminescent reporter assays. PPRX-1701 administration leads to improved survival in the GL261 glioblastoma mouse model (median survival 30 days (control), 47 days (treated), p < 0.0001). Treatment with PPRX-1701 was associated with alterations in the tumor immune microenvironment, with reduced Tregs and pro-tumor macrophages, and increased CD8+ T cells. Further mechanistic studies have shown that PPRX-1701/BiA blocks the expression of multiple immunosuppressive molecules in GBM downstream of interferon-γ (IFNγ) including PD-L1 and indoleamine 2,3-dioxygenase 1 (IDO1) - a key enzyme in the tryptophan-kynurenine-aryl hydrocarbon receptor (Trp-Kyn-AhR) immunosuppressive pathway. BiA promoted more effective T-cell mediated tumor cell killing using patient derived glioblastoma ex vivo co-culture models.

Conclusion: This data supports further development of PPRX-1701 as a candidate immunotherapeutic agent for glioblastoma treatment. Ongoing pre-clinical studies are investigating combination with other relevant therapies.

Citation Format: Mykola Zdioruk, Michal Nowicki, Bin Wu, Paul Boucher, Yuji Takeda, Weiyi Li, E Antonio Chiocca, Sean E. Lawler. PPRX-1701, a deliverable nanoparticle formulation of 6-bromo-acetoxime, blocks tumoral IDO1 expression and shows efficacy in immunocompetent murine glioblastoma models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4235.
Abstract 4236: Temporal inhibition of BCAT1 alters metal homeostasis leading to reversal of terminal exhaustion of CD8 T cells, increased cytotoxicity, and increased efficacy of checkpoint inhibition in cancer
Authors: Papathanassiu Adonia E. , Li Weixing , Vu Hong A.
Published: June 2022

We have previously demonstrated that BCAT1, the enzyme responsible for the reversible transamination of leucine in the cytosol, is a druggable target in immune-oncology: the small molecule inhibitor ERG245 dramatically increases the efficacy of anti-PD-1 treatment in the moderately immunogenic CT26 colon cancer model. We have also shown that Bcat1 gene expression is enriched in exhausted CD4+ and CD8+ intratumoral cells in cancer patients from diverse cancers. Here, we illustrate that the adoptive cell transfer (ACT) of murine CD8+ T cells treated with ERG245 increased the median survival of CT26 tumor-bearing mice from 25 days, observed with the ACT of untreated CD8+ T cells, to 32 days. This suggested that inhibition of BCAT1 prevented the known exhaustion of adoptively transferred CD8+ T cells, induced by the tumor microenvironment of CT26 tumors. To confirm this hypothesis, we developed an in vitro model of generating terminally exhausted (PD-1+TIM-3+GZMB+CXCL13+) CD8+ T cells by subjecting the cells to consecutive cycles of αCD3/αCD28 activation in the presence of TGF-β. Addition of ERG245 in the last activation cycle decreased terminal exhaustion of the cells. Mechanistically, bulk RNAseq experiments indicated and ICP analysis confirmed that inhibition of BCAT1 interfered with metal homeostasis leading to increased concentrations of Fe in the mitochondria and decreased concentrations of Zn in the nucleus of newly activated CD8+ T cells. The immediate impact of ERG245 treatment on the cells included a general decrease in the genes of processes depending on proper metal equilibrium such as cholesterol biosynthesis and ribosome biogenesis. Withdrawal of BCAT1 restored or reversed the cell phenotype leading to epigenetically altered CD8+ T cells with decreased histone acetyltransferase and histone demethylase presence, increased cytotoxicity, and increased ribosome biogenesis. Collectively, the data suggest that temporal inhibition of BCAT1 inhibition induces profound effects on CD8+ T cells including increased cytotoxicity and suppression of terminal exhaustion, thus rendering the cells rescuable by anti-PD-1 therapy.

Citation Format: Adonia E. Papathanassiu, Weixing Li, Hong A. Vu. Temporal inhibition of BCAT1 alters metal homeostasis leading to reversal of terminal exhaustion of CD8 T cells, increased cytotoxicity, and increased efficacy of checkpoint inhibition in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4236.
Abstract 4240: In vivo assessment of AICD and cytokine release upon treatment of OKT3 and CD3 bispecific antibody in homozygous CD3EDG HuGEMM™
Authors: He Daniel XF
Published: June 2022

Introduction: CD3 bispecific antibodies have transformed the therapeutic landscape of immunotherapy for some hematological malignancies, however, the clinical therapeutic effects of CD3 bispecific therapies is still under investigation for solid tumors. Moreover, CD3 bispecific antibody-mediated tumor targeting as well as T cell engagement have resulted in cytokine release syndrome (CRS), increased on-target/off-tumor toxicities and poor T cell infiltration, which may affect safety and limit therapeutic efficacy. To better understand the relationship between T cell activation and systemic cytokine release in the context of CD3 bispecific antibody treatment, a homozygous human CD3EDG HuGEMM࣪ preclinical model was developed.

Methods: The homozygous CD3EDG HuGEMM mice, which express human CD3ε/CD3δ/CD3γ on the surface of T cells, were subcutaneously inoculated with MC38 or MC38-hEpCAM HuCELL™ syngeneic tumors and treated with vehicle, anti-mPD-1 (RMP1-14), OKT3, and anti-hCD3×hEpCAM. For efficacy studies, mouse body weight and tumor volume were measured twice weekly and tumor growth inhibition (TGI%) was determined. To investigate OKT3 or CD3 bispecifics-induced cytokine release, mouse body weight was monitored daily and several inflammatory and proinflammatory cytokines in the serum were detected by MSD.

Results: Firstly, anti-mPD-1 treatment (5 mg/kg and 15 mg/kg i.p.) of homozygous CD3EDG mice engrafted with MC38 syngeneic tumors led to 42% and 62% TGI, respectively. OKT3 treatment of MC38-hEpCAM bearing homozygous CD3EDG HuGEMM promoted tumor growth (TGI= -80%), likely due to activation-induced cell death (AICD) of T cells. In addition, CRS was induced within 24 hours of OKT3 dosing, with IL-2, IL-6, and TNF-α peaking 2 hr post the 1st dose, and IFN-γ, IL-10 and IL-5 peaking 6 hr post the 1st dose. In contrast, no significant cytokine release was observed upon anti-hCD3×hEpCAM treatment despite remarkable TGI, indicating that the delicate balance of in vivo T cell activation and T cell cytotoxicity is crucial for effective tumor killing by CD3 bispecific antibodies or engagers.

Conclusions: Our CD3EDG HuGEMM and HuCELL models provide a predictive platform for in vivo efficacy and safety assessment of CD3 bispecific or trispecific antibodies. The uncoupling of systemic cytokine release and T cell cytotoxicity via CD3 bispecific or trispecific antibodies provides a biological rationale to clinically explore preventative treatment approaches to avoid or reduce CRS-related toxicity, as well as combination approaches to increase selectivity and efficacy.

Citation Format: Daniel XF He. In vivo assessment of AICD and cytokine release upon treatment of OKT3 and CD3 bispecific antibody in homozygous CD3EDG HuGEMM™ [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4240.
Abstract 433: Colorectal and gastric cancer screening rates in Korea during the COVID-19 pandemic
Authors: Seo Seung Hee , Park Hyeree , Park Jong Heon , Keam Bhumsuk , Yoo Shin Hye , Shin Aesun
Published: June 2022

Background: The COVID-19 pandemic has disrupted healthcare delivery, which is widely discussed as the distraction effect. This study aimed to estimate the distraction effect of the COVID-19 pandemic in Korea by analyzing colorectal and gastric cancer screening rates in the years 2019 and 2020.

Methods: Information of eligible population who had colorectal and gastric cancer screening provided by the National Cancer Screening Program in the years 2019 and 2020 was collected. Participation rates were analyzed by age group, sex, geographic region, and calendar month. Percentage change was calculated by dividing the percentage point difference by the screening rate of the reference period (2019).

Results: Overall, the colorectal and gastric cancer screening rates had decreased in 2020, compared to the reference period. For colorectal cancer, the screening rate decreased from 68.3% in 2019 (5,886,319 participants/14,526,424 eligible population) to 54.6% in 2020 (5,135,218/9,410,525) For gastric cancer, the screening rates decreased from 61.9% in 2019 (7,194,489/11,625,627) to 54.6% in 2020 (6,244,491/11,439,246). In March, during the first wave, the screening rates declined sharply (percentage change: colorectal, 56.6%; gastric, 57.3%). Although the screening rates had rebounded aftermath, they declined again in December, during the third wave (percentage change: colorectal, 17.0%; gastric, 13.8%). According to specific-age group, we found a substantial decline in screening rates for older adults aged 80~84, and those over 85 (percentage change: colorectal, 19.0% & 23.0%; gastric, 17.4% & 25.1% respectively).

Conclusion: During the COVID-19 pandemic, the screening rates for both colorectal and gastric cancer decreased. There was a substantial decline during the first and the third waves of the epidemic, in March and in December. The older adults group showed the highest reduction in screening rates. However, comparing the screening rate by region and sex, we did not find a significant difference. Delayed cancer diagnosis or excess death due to distraction effect of the COVID-19 pandemic has not yet been detected in Korea, therefore, further studies are needed.

Citation Format: Seung Hee Seo, Hyeree Park, Jong Heon Park, Bhumsuk Keam, Shin Hye Yoo, Aesun Shin. Colorectal and gastric cancer screening rates in Korea during the COVID-19 pandemic [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 433.
Abstract 439: Physical activity among male cancer survivors during the COVID-19 pandemic
Authors: McGrath Colleen B. , Shreves Alaina H. , Stopsack Konrad , Cheung Lilian , Fisher Ann , Markt Sarah , Mucci Lorelei A.
Published: June 2022

Introduction: The COVID-19 pandemic has greatly disrupted the lives of cancer survivors. Beyond being at increased risk for COVID-19 infection and severe complications, cancer survivors may be at higher risk of other consequential health outcomes compared to those without a history of cancer. Engagement in physical activity has been shown to positively affect cancer survivorship outcomes, and as such, it is important to assess physical activity habits during the pandemic of cancer survivors.

Aim: To investigate the individual-level physical activity among male cancer survivors during the COVID-19 pandemic and compare to men without cancer.

Methods: Participants of the Health Professionals Follow-up Study, enrolled since 1986, were asked to self-report health behaviors during the pandemic on three web-based questionnaires administered during the COVID-19 pandemic (baseline COVID: October 2020, first follow-up: January 2021, second follow-up: April 2021). Physical activity measures were analyzed descriptively between cancer survivors and individuals without a history of cancer. Outcomes were recoded dichotomously to reflect either: healthful (i.e., higher engagement since pandemic) vs unchanged/unhealthful behavior or high vs low engagement in an activity. Logistic regression models were employed to assess association with cancer survivor status and were adjusted for covariates such as age, race, pre-pandemic BMI, pre-pandemic physical activity, and other health information, as appropriate.

Results: Of 4,416 men who completed the baseline COVID-19 questionnaire, 962 were cancer survivors (after excluding those with non-melanoma skin cancer). Of all eligible men (median age: 78 years) reporting on physical activity, over 50% walked for at least 2-3 hours per week, over 10% used a stationary bike for at least 1 hour per week, 14% engaged in yoga for at least 1 hour per week, and nearly 20% engaged in vigorous activity for at least 1 hour per week. Further, 42% engaged in high (1+ times per day) levels of mindfulness and 24% engaged in high (1+ times per day) levels of yoga. Engagement in vigorous physical activity was significantly lower among cancer survivors compared to individuals without a history of cancer (Chi-square p = 0.01).

Conclusion: Our findings suggest older men had high engagement in physical activity during the COVID-19 pandemic, with vigorous physical activity engagement significantly lower in cancer survivors.

Citation Format: Colleen B. McGrath, Alaina H. Shreves, Konrad Stopsack, Lilian Cheung, Ann Fisher, Sarah Markt, Lorelei A. Mucci. Physical activity among male cancer survivors during the COVID-19 pandemic [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 439.
Abstract 5009: DKK1 is a potential target for enhancing the efficiency of radioimmunotherapy in head and neck squamous carcinoma
Authors: YE Xinyu , Zhang JIAN , Lu Yi , Gong Yingxuan , Jiang Xinyu , Li Yueming , Wang Yinghao , Li Xiuzhi , Liu Jingwen , Quan Rencui
Published: June 2022

Immune checkpoint inhibitors (ICIs) have been approved to treat various types of tumors, including head and neck squamous carcinoma (HNSC). However, most HNSC patients do not respond to ICIs. Radioimmunotherapy has been proposed to enhance the immune response rate in HNSC. Herein, we aimed to explore the effect of DKK1 on radiotherapy and immunotherapy in HNSC. We collected the gene expression profile and clinical information of HNSC patients from TCGA, GEO, and ICGC. The immune cell infiltration, level of related pathways and biological processes, signature scores of gene sets of interest were assessed using CIBERSORT, GSEA or GSVA respectively. One of the genes, Dickkopf-1 (DKK1), a secreted protein which plays important roles in the Wnt signaling pathways, was identified because of its significantly higher expression in HNSC. Then, we confirmed the DKK1 expression at protein level by immunohistochemistry of HNSC tissue microarray. CCK8, apoptosis detection and survival curves were performed to investigate the response of DKK1-knockdown HSC-3 cell line to radiation. We found the mRNA and protein expression level of DKK1 was significantly higher in HNSC tissue. The DKK1high group had a shorter survival time in both disease-free survival and overall survival than the DKK1low group. The DKK1high group showed a more immunosuppressive microenvironment with lower infiltration of T cells and higher infiltration of MDSCs. Furthermore, the DKK1high group was enriched in radioresistance related to wound healing, angiogenesis, and autophagy. Patients in the DKK1high group who received radiotherapy had much poorer disease-free survival and overall survival than those in the DKK1low group. HSC-3 cell line was more sensitive to radiation after knockdown of DKK1 by siRNA. Finally, we established a risk score system based on the 9 genes from 41 DKK1-associated immunomodulators and created a nomogram model to predict the prognosis of the patients. Our data show that DKK1 can affect both radiotherapy and immunotherapy in HNSC, suggesting that DKK1 can be a potential target for radioimmunology in HNSC.

Citation Format: Xinyu YE, JIAN Zhang, Yi Lu, Yingxuan Gong, Xinyu Jiang, Yueming Li, Yinghao Wang, Xiuzhi Li, Jingwen Liu, Rencui Quan. DKK1 is a potential target for enhancing the efficiency of radioimmunotherapy in head and neck squamous carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5009.
Abstract 5014: The landscape of ERBB2 mutations in Chinese patients with solid tumors
Authors: Su Xiangyu , Zhao Hongmei
Published: June 2022

Background: Receptor tyrosine kinase (ERBB2) is altered by mutations and amplifications in various cancer types. Meanwhile, FDA approved some drugs to use for variants in ERBB2. However, the landscape of ERBB2 mutations and copy number variants (CNV) in pan-cancer is unknown in Chinese.

Methods: 599 gene-panel by next-generation sequencing (NGS) was performed on 2,570 patients with solid tumors including non-small cell lung cancer (NSCLC) (n = 660), esophagogastric (n = 89), colorectal (n = 966), breast (n = 156) and gastric cancer (n = 699). The mutations and CNV in ERBB2 were detected for characterize the landscape in Chinese patients with solid tumors.

Results: The frequency of single nucleotide variants (SNV) and CNV in ERBB2 was 9% and 4.3% in pan-cancer and the rate of variants was 13.3%. The most frequency of CNV was occurred in breast cancer and the last was in non-small cell lung cancer (13.5% vs 1.1%). Nevertheless, the rate of SNV in different cancer species was almost the same as in pan-cancer (mean: 8.8%). The higher rate of variants in ERBB2 was breast cancer and the lower was NSCLC. The cancer types with the highest incidence of ERBB2 variants were the following: breast (22.4%), gastric adenocarcinoma (18.3%), esophagogastric cancer (11.2%), colorectal cancer (10.8%) and NSCLC (9.7%).

Conclusion: Based on the results, the profile of variants in ERBB2 revealed more patients may profit from FDA-approval drugs in China. The patients with somatic mutations in ERBB2 are treated with trastuzumab deruxtecan and adotrastuzumab emtansine in NSCLC. The patients with amplification are treated with trastuzumab deruxtecan in most tumors, but margetuximab and chemotherapy can cure breast cancer, according to FDA-approval.

Keywords: ERBB2 mutations, CNV, SNV, solid tumors

Citation Format: Xiangyu Su, Hongmei Zhao. The landscape of ERBB2 mutations in Chinese patients with solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5014.