bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 6209: O6-methylguanine as the junction of MGMT and PARP1-mediated repair pathways
Authors: Cropper Jodie D. , Alimbetov Dauren S. , Brown Kevin T. , Robles Andrew , Likhotvorik Rostislav I. , Guerra James T. , Chen Yidong , Kwon Youngho , Kurmasheva Raushan T. 
Published: April 2023

Abstract
Temozolomide is the first-choice DNA alkylating agent and has been commonly used in oncology over the last several decades. The cytotoxicity that temozolomide elicits through the methylation of guanine and adenine residues often becomes the limiting factor in effective treatment. Despite growing evidence of dysregulated alkylating DNA damage repair as a driving force of genome instability leading to cancer, neurological diseases, and premature aging, little is currently known about the coordinated role of PARP1 and MGMT (O6-methylguanine methyltransferase) enzymes in the repair of temozolomide-induced methylated DNA lesions. A major PARP1 function in DNA damage is facilitation of repair of the methylated DNA lesions, N6-methyladenine and N7-methylguanine, via base excision repair (BER); while MGMT restores guanine in O6-methylguanine (O6meG), the most cytotoxic adduct, by a one-step catalysis. It is generally thought that BER and MGMT represent two distinct mechanisms for removing DNA damage induced by alkylating agents; however, using a number of advanced cell-free and cell-based approaches, we provided evidence for direct (DNA-independent) and indirect (through PARylation) interaction between PARP1 and MGMT and demonstrated a functional crosstalk between these repair pathways. Particularly, O6meG repair activity is increased once PARP1 PARylates MGMT. Further, longer (more clinically relevant) exposure to temozolomide induced stronger MGMT PARylation in cells, indicating that the PARP1-MGMT interaction is important for enhanced O6meG repair and cell survival. As PARP1-MGMT complex forms in a variety of cancer cell types, our findings have strong implications for the development of an effective cancer therapy for cells dependent on PARP1 and MGMT mediated DNA repair.
Citation Format: Jodie D. Cropper, Dauren S. Alimbetov, Kevin T. Brown, Andrew Robles, Rostislav I. Likhotvorik, James T. Guerra, Yidong Chen, Youngho Kwon, Raushan T. Kurmasheva. O6-methylguanine as the junction of MGMT and PARP1-mediated repair pathways. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6209.
Abstract 6214: FANCA promotes transcription-coupled homologous recombination by catalyzing R-loops formation
Authors: Li Fang 
Published: April 2023

Abstract
R loops arise from hybridization of RNA transcripts with template DNA during transcription, which are not only cause DNA damage in certain contexts as cancer hallmarks but also be important regulators of cellular processes. Recent findings revealed that DNA double-strand breaks (DSBs) elicit RNA-DNA hybrid formation. The RNA moiety of the R-loop displays an extraordinary potential to regulate multiple steps of homologous recombination (HR) by substituting for the double-stranded DNA (dsDNA) substrate on which DSB repair processes naturally occur. Here, we use the Damage At RNA Transcription assay to reveal colocalization of FANCA with R-loops in a highly transcribed genomic locus upon DNA damage. We further demonstrate FANCA participates in forming R-loops in the initial DSBs repair stage and assists in removing R-loops later. Besides, we find that highly purified human FANCA anneals synthetic single-stranded RNA (ssRNA) and ssDNA species to R-loops and binds R-loop substrates with high affinity, preferring guanine-rich sequences in vitro. Importantly, we illustrate that FANCA promotes HR efficiency via catalyzation of DNA: RNA hybrids at DSBs sites. Finally, a series of RNA and R-loop substrates are found to stimulate ID2 monoubiquitination, with activity corresponding to remove transient R- loops in later HR stage. In summary, our results support a mechanism whereby FANCA promotes the formation of temporary R-loops by annealing ssRNA and ssDNA species at DSBs in transcribed regions, thereby stimulating HR.
Citation Format: Fang Li. FANCA promotes transcription-coupled homologous recombination by catalyzing R-loops formation. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6214.
Abstract 6222: Clinical impact of p53 and AXL immunostaining on the efficacy of immune checkpoint inhibitor-based therapy after osimertinib treatment in patients with epidermal growth factor mutant non-small cell lung cancer
Authors: Morimoto Kenji , Yamada Tadaaki , Tokuda Shinsaku , Takayama Koichi 
Published: April 2023

Abstract
Background: Current evidence indicates that immune checkpoint inhibitors (ICIs) have a limited efficacy in patients with lung cancer harboring epidermal growth factor receptor (EGFR) mutations. However, there is a lack of data on the efficacy of ICIs after osimertinib treatment, and the predictors of ICI efficacy are unclear.
Methods: We retrospectively assessed consecutive patients with EGFR-mutant NSCLC who received ICI-based therapy after osimertinib treatment at 10 institutions in Japan, between March 2016 and March 2021. Immunohistochemical staining was used to evaluate the expression of p53 and AXL. The deletions of exon 19 and the exon 21 L858R point mutation in EGFR were defined as common mutations; other mutations were defined as uncommon mutations.
Results: A total of 36 patients with advanced or recurrent EGFR-mutant NSCLC were analyzed. In multivariate analysis, p53 expression in tumors was an independent predictor of PFS after ICI-based therapy (p = 0.002). In patients with common EGFR mutations, high AXL expression was a predictor of shorter PFS and overall survival after ICI-based therapy (log-rank test; p = 0.04 and p = 0.02, respectively).
Conclusion: The levels of p53 in pretreatment tumors may be a predictor of ICI-based therapy outcomes in patients with EGFR-mutant NSCLC after osimertinib treatment. High levels of AXL in tumors may also be a predictor of ICI-based therapy outcomes, specifically for patients with common EGFR mutations. Further prospective large-scale investigations on the predictors of ICI efficacy following osimertinib treatment are warranted.
Citation Format: Kenji Morimoto, Tadaaki Yamada, Shinsaku Tokuda, Koichi Takayama. Clinical impact of p53 and AXL immunostaining on the efficacy of immune checkpoint inhibitor-based therapy after osimertinib treatment in patients with epidermal growth factor mutant non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6222.
Abstract 6242: Inhibition of BIRC5/survivin by LQZ-7I inhibits neuroblastoma growth while hemizygosity of BIRC5 does not: implications for therapy of neuroblastoma
Authors: Dorneburg Carmen , Galliger Celimene , Rasche Voker , Lechel Andre , Barth Thomas F. , Debatin Klaus-Michael , Beltinger Christian 
Published: April 2023

Abstract
Overexpression of survivin, a crucial regulator of the mitotic spindle checkpoint, is associated with poor prognosis in neuroblastoma (NB). Transcriptional inhibitors of survivin have been tested in clinical trials. However, results have been disappointing. We thus investigated the small molecules LQZ-7I and S12 that inhibit dimerization of survivin protein and compared their growth-inhibiting efficacy with that of markedly decreased survivin expression in a novel transgenic NB mouse. Mice hemizygous for BIRC5 were crossed with TH-MYCN mice to generate BIRC5+/−/MYCNtg/+ mice. NB incidence, growth and retransplantation capacity were assessed. In vitro, LQZ-7I and S12 were used to inhibit survivin protein interactions and the effects on proliferation and cell cycle of NB cells were investigated. BIRC5 hemizygous mice developed NB although mRNA and protein expression of survivin was markedly decreased. Surprisingly, incidence and latency of the NB that developed in the BIRC5+/−/MYCNtg/+ mice did not differ from the NB in the TH-MYCN mice, and tumor growth and survival of the mice was not affected. In stark contrast, the survivin interaction inhibitors LQZ-7I and S12 abolished anchorage-independent growth and proliferation of NB cell lines. Reduced growth of NB cells resulted from defects in mitosis induced by LQZ-7I or S12 or. LQZ-7I was the more efficient inhibitor of NB cells while S12 was not able to reduce tumor growth in a xenograft model. Taken together, these results support the notion that inhibiting survivin interaction is more efficacious in NB than inhibiting survivin transcription.
Citation Format: Carmen Dorneburg, Celimene Galliger, Voker Rasche, Andre Lechel, Thomas F. Barth, Klaus-Michael Debatin, Christian Beltinger. Inhibition of BIRC5/survivin by LQZ-7I inhibits neuroblastoma growth while hemizygosity of BIRC5 does not: implications for therapy of neuroblastoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6242.
Abstract 6271: Discovery of BR1733 for the treatment of SWI/SNF deficient or highly vascularized solid tumor
Authors: Wang Xinghao , Ma Shichao , Xie Min (Bella) , Wang Lele , Wang Yajun , Zhang Song , Chen Sheng , Zhang Lynette , Zhou Yongqi , Zhao Mengxi , Li Dandan , Li Guobin , Fan Xiao , Zhang Hailong 
Published: April 2023

Abstract
Polycomb repressive complex 2 (PRC2) catalyze the writing of H3K27me3 epigenetic marker and suppresses the expression of genes including tumor suppressors. Activation mutation of EZH2, the catalytic subunit of the PRC2 complex, drives the progression of tumors such as DLBCL. The embryonic ectoderm development (EED) protein acts as the scaffolding and H3K27me3-binding subunit of PRC2 and is essential for its activity. We have developed potent, selective, and orally bioavailable EED inhibitor BR1733. BR1733 blocks the interaction between EED and H3K27me3, and inhibits catalytic activity of PRC2. BR1733 showed superior PK profile across species and exhibited tumor growth inhibition against several B cell lymphoma CDX models. Indication expansion studies demonstrated that BR1733 could inhibit solid tumors with SWI/SNF loss-of-function mutation only when both CDKN2A and TET1 are expressed. BR1733 also inhibited tumor angiogenesis and showed tumor growth inhibition in several CDX models of highly vascularized solid tumors such as HCC and RCC. BR1733 is currently in Phase I clinical trials.
Citation Format: Xinghao Wang, Shichao Ma, Min (Bella) Xie, Lele Wang, Yajun Wang, Song Zhang, Sheng Chen, Lynette Zhang, Yongqi Zhou, Mengxi Zhao, Dandan Li, Guobin Li, Xiao Fan, Hailong Zhang. Discovery of BR1733 for the treatment of SWI/SNF deficient or highly vascularized solid tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6271.
Abstract 6381: Quantitative multiplex analysis of soluble and cellular immune checkpoint proteins in response to interferon gamma across multiple murine tumor models
Authors: Lie Wen-Rong , Bucktrout Ryan , Chakraborty Sanjukta , Orlando Andrea , Serganova Inna , Kornmeier Christine , Hoberg James , Zappasodi Roberta 
Published: April 2023

Abstract
Immune checkpoint proteins are key regulators of the immune system and drug targets of cancer immunotherapy. Immune checkpoint molecules have been found on the cell surface of various tumor cells and immune cells as immune activating or inhibitory receptors and ligands. Recent studies have shown these immune checkpoint proteins can undergo alternative splicing or proteolytic cleavage leading to soluble isoforms. IFNγ is a pleiotropic and multifunctional cytokine commonly released by cytotoxic immune cells. IFNγ production can be enhanced in response to immunotherapy and further modulates the expression of immune checkpoints in the tumor microenvironment. To better understand the immune checkpoint signatures in tumors, we developed a 28-plex mouse checkpoint protein multiplex immunoassay for quantitative analysis of soluble (secreted) and cellular immune checkpoint proteins. Using this immunoassay, we tested 16 mouse cell lines of tumor (n=13) and normal tissues as control (n=3): 2 melanomas (B16F10, YUMM1.7), 3 mammary carcinoma (4T1, NT5, AT-3), 1 lung carcinoma (LLC), 1 prostate cancer (MycCaP), 1 fibrosarcoma (MCA205), 1 ovarian cancer (ID8), 1 bladder cancer (MB49), 1 glioma (CT-2A), 2 blood cancer (RAW, EL4), 1 dendritic cells (DC2.4), 1 myoblast cells (C2C12), and 1 endothelial cells (bEnd.3). We analyzed changes in immune checkpoint protein expression and secretion in these cell lines cultured in normal conditions or upon exposure to IFNγ to reflect an immune inflamed microenvironment. Cells were cultured in 96-well plate, 100 mm, or 150 mm Petri dishes, and treated with either 10 ng/ml or 100 ng/mL mouse IFNγ. Cell culture supernatants and cell lysates were harvested after 6h, 12h, or 24h incubation with IFNγ and processed for multiplex Luminex bead-based immunoassay. The soluble and cellular checkpoint proteins most substantially modulated by IFNγ treatment in these cell lines included: CD137, BTLA, HVEM, PD-L1. The tumor-specific signature of cellular and soluble checkpoint proteins and its response to IFNγ may have implications in the tumor microenvironment and in the outcome to immunotherapy.
Citation Format: Wen-Rong Lie, Ryan Bucktrout, Sanjukta Chakraborty, Andrea Orlando, Inna Serganova, Christine Kornmeier, James Hoberg, Roberta Zappasodi. Quantitative multiplex analysis of soluble and cellular immune checkpoint proteins in response to interferon gamma across multiple murine tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6381.
Abstract 6391: Development of a novel strategy for cancer immunotherapy based on tumor immunogenicity improvement by HLA-drug interaction
Authors: Susukida Takeshi , Sasaki So-ichiro , Shirayanagi Tomohiro , Aoki Shigeki , Ito Kousei , Hayakawa Yoshihiro 
Published: April 2023

Abstract
[Purpose] Tumors with low T cell infiltrates (poor immunogenicity) display lower probability of clinical response to immune checkpoint inhibitors. To achieve higher immunotherapy efficacy, it is imperative to establish a novel strategy for improving immunogenicity. Abacavir (ABC), an anti-HIV drug, binds to the specific allele of human leukocyte antigen (HLA-B*57:01) and activate CD8+ T cells by presenting altered abnormal peptides. In this study, we considered the immune interaction between ABC and HLA-B*57:01 improving immunogenicity in poorly immunogenic tumors leading to a potent anti-cancer effect.
[Methods] Mice were inoculated subcutaneously with tumor cells into the right flanks and interperitoneally treated with either ABC 5 mg or vehicle (water) for consecutive 9 days (B16F10) or 13 days (3LL) after tumor inoculation. Each tumor size was measured using vernier calipers on every 2 days. Activation, proliferation, and IFN-γ secretion of tumor infiltrating CD8+ T cells were analyzed by FACS.
[Results and Discussion] ABC treatment showed significant tumor growth inhibition associated with CD8+ T cell infiltration into tumor in mice inoculated with HLA-B*57:01 expressing B16F10 melanoma or Lewis lung carcinoma (3LL) cells, but neither in HLA-B*57:03 (negative allele)-expressing nor control tumors inoculated mice. Moreover, the tumor infiltrating CD8+ T cell were immune-activated and proliferated, with secreting IFN-γ. In contrast, ABC-induced anti-tumor effect was abrogated in CD8+ T cell-depleted mice, IFN-γ KO mice, and CXCR3-blocked mice. The combination therapy with anti-PD-1 antibody treatment induced better inhibition of tumor growth than ABC monotherapy in HLA-B*57:01 expressing B16F10 inoculated mice. These results suggested that ABC/HLA-B*57:01 interaction could improve tumor immunogenicity associated with CD8+ T cell-mediated anti-tumor effect in poorly immunogenic tumors. This finding lays a foundation to develop a novel drug-induced cancer immunotherapy targeting immune resistant tumors.
Citation Format: Takeshi Susukida, So-ichiro Sasaki, Tomohiro Shirayanagi, Shigeki Aoki, Kousei Ito, Yoshihiro Hayakawa. Development of a novel strategy for cancer immunotherapy based on tumor immunogenicity improvement by HLA-drug interaction [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6391.
Abstract 6420: Harnessing immune responses in prostate MMRd tumors treated with immune checkpoint blockade
Authors: Badia Marcel Arias , Fan Zenghua , Lwin Yee May , Chen PeiXi , Srinath Aahir , Fong Lawrence 
Published: April 2023

Abstract
There is increasing evidence correlating tumor mutational burden with response to immunotherapy in many different types of cancer. Some tumors show high microsatellite instability (MSI-H) as a consequence of the loss of function of mismatch repair (MMR) genes, which would resolve DNA damage in normal conditions. MSH2 plays a critical role in MMR, and several studies have identified mutations in MSH2 as key drivers of MSI in tumors. In preclinical mouse models, MMR deficiency and high microsatellite instability have been previously shown to translate into higher sensitivity to anti-PD-1 treatment. Despite the advances led by the recent tumor-agnostic approval of checkpoint inhibitors for highly mutated tumors, response rates among MMR-deficient (MMRd) tumors in humans are variable, and the mechanisms behind such heterogeneity are still poorly understood. We successfully knocked out the MSH2 gene in the murine prostate adenocarcinoma TRAMP-C2 cell line by CRISPR gene editing. By sequential passaging, we generated a MSH2-KO subclonal population that presents MSI and MMR deficiency, validated by increased tumor mutational burden (TMB) observed by exome sequencing. In studies where we challenged immunodeficient and immunocompetent mice with MMR-proficient (MMRp) and MMRd tumors, the latter showed increase immunogenicity, which led us to interrogate and better characterize such immune responses in the context of immune checkpoint blockade by anti-PD-1.In our studies, MMRd tumor-infiltrating T cells presented significantly enhanced effector and cytotoxic profiles, which likely led to improved tumor control with or without anti-PD-1. We observed an intriguingly lower frequency of SPAS-1 (a well-known TRAMP-C2 immunodominant epitope) antigen-specific T cells in the tumor-reactive fraction of MMRd infiltrates compared to MMRp, which prompted us to interrogate tumor-infiltrate gene expression, TCR repertoire and the potential expansion of multiple antigen-reactive subsets against MMRd tumors in successful immune responses by single cell RNA sequencing and functional ex vivo studies. We also interrogated TCR repertoire data from patients harboring MMRd tumors to add translatability to our findings in mice.Our results constitute a relevant addition to the understanding of immune responses in MMRd tumors and the potential features that could be exploited to improve response rates in immunotherapeutic strategies targeting such malignancies.
Citation Format: Marcel Arias Badia, Zenghua Fan, Yee May Lwin, PeiXi Chen, Aahir Srinath, Lawrence Fong. Harnessing immune responses in prostate MMRd tumors treated with immune checkpoint blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6420.
Abstract 6423: Targeting an autophagy regulator augments antitumor immunity and immunotherapy
Authors: Bao Yi , Qiao Yuanyuan , Chinnaiyan Arul 
Published: April 2023

Abstract
Immunotherapy has strikingly changed the landscape of cancer treatment, yet many patients fail to respond to the therapy exhibiting primary resistance. Accumulating evidence has supported that autophagy inhibition may sensitize tumor to immunotherapy. Here, we found that pharmaceutical or genetic inhibition of an autophagy regulator induces MHC class I surface expression in cancer cells. In a co-culture of OT1 CD8+ T cells and ovalbumin-expressing cancer cells, inhibition of the regulator enhances CD8+ T cell killing and increases functional and proliferative CD8+ T cells. Concordantly, genetic depletion or inhibition of the regulator elevates MHC class I in tumor cells, reduces tumor growth, and increases intratumoral functional CD8+ T cells in syngeneic mouse models. Furthermore, we found that inhibition of the regulator sensitizes syngeneic tumors to anti-PD1 therapy. Collectively, inhibition of this autophagy regulator augments antitumor immunity and immunotherapy via inducing MHC class I surface expression in cancer cells.
Citation Format: Yi Bao, Yuanyuan Qiao, Arul Chinnaiyan. Targeting an autophagy regulator augments antitumor immunity and immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6423.