bluuebunny/crossref_metadata_2025 huggingface dataset:
Targeted Deep Sequencing of Bladder Tumors Reveals Novel Associations between Cancer Gene Mutations and Mutational Signatures with Major Risk Factors
Authors: Koutros Stella , Rao Nina , Moore Lee E. , Nickerson Michael L. , Lee Donghyuk , Zhu Bin , Pardo Larissa A. , Baris Dalsu , Schwenn Molly , Johnson Alison , Jones Kristine , Garcia-Closas Montserrat , Prokunina-Olsson Ludmila , Silverman Debra T. , Rothman Nathaniel , Dean Michael
Published: April 2021

Purpose:

Exome- and whole-genome sequencing of muscle-invasive bladder cancer has revealed important insights into the molecular landscape; however, there are few studies of non–muscle-invasive bladder cancer with detailed risk factor information.

Experimental Design:

We examined the relationship between smoking and other bladder cancer risk factors and somatic mutations and mutational signatures in bladder tumors. Targeted sequencing of frequently mutated genes in bladder cancer was conducted in 322 formalin-fixed paraffin-embedded bladder tumors from a population-based case–control study. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI), evaluating mutations and risk factors. We used SignatureEstimation to extract four known single base substitution mutational signatures and Poisson regression to calculate risk ratios (RR) and 95% CIs, evaluating signatures and risk factors.

Results:

Non-silent KDM6A mutations were more common in females than males (OR = 1.83; 95% CI, 1.05–3.19). There was striking heterogeneity in the relationship between smoking status and established single base substitution signatures: current smoking status was associated with greater ERCC2-Signature mutations compared with former (P = 0.024) and never smoking (RR = 1.40; 95% CI, 1.09–1.80; P = 0.008), former smoking was associated with greater APOBEC-Signature13 mutations (P = 0.05), and never smoking was associated with greater APOBEC-Signature2 mutations (RR = 1.54; 95% CI, 1.17–2.01; P = 0.002). There was evidence that smoking duration (the component most strongly associated with bladder cancer risk) was associated with ERCC2-Signature mutations and APOBEC-Signature13 mutations among current (Ptrend = 0.005) and former smokers (P = 0.0004), respectively.

Conclusions:

These data quantify the contribution of bladder cancer risk factors to mutational burden and suggest different signature enrichments among never, former, and current smokers.
Can Biomarkers Guide Oncolytic Virus Immunotherapy?
Authors: Kaufman Howard L.
Published: April 2021

Defects in tumor cell IFNγ signaling is associated with resistance to immune checkpoint inhibitors. Recently, these defects were found to confer increased sensitivity to oncolytic virus infection. Differential expression of innate sensing elements in tumor cells may serve as predictive biomarkers of oncolytic virus immunotherapy in patients with cancer.

See related article by Nguyen et al., p. 3432
High-Throughput Screening Identifies Idasanutlin as a Resensitizing Drug for Venetoclax-Resistant Neuroblastoma Cells
Authors: Vernooij Lindy , Bate-Eya Laurel T. , Alles Lindy K. , Lee Jasmine Y. , Koopmans Bianca , Jonus Hunter C. , Schubert Nil A. , Schild Linda , Lelieveld Daphne , Egan David A. , Kerstjens Mark , Stam Ronald W. , Koster Jan , Goldsmith Kelly C. , Molenaar Jan J. , Dolman M. Emmy M.
Published: April 2021

Neuroblastoma tumors frequently overexpress the anti-apoptotic protein B-cell lymphoma/leukemia 2 (BCL-2). We previously showed that treating BCL-2–dependent neuroblastoma cells with the BCL-2 inhibitor venetoclax results in apoptosis, but unfortunately partial therapy resistance is observed. The current study describes the identification of drugs capable of resensitizing venetoclax-resistant neuroblastoma cells to venetoclax. To examine these effects, venetoclax resistance was induced in BCL-2–dependent neuroblastoma cell lines KCNR and SJNB12 by continuous exposure to high venetoclax concentrations. Non-resistant and venetoclax-resistant neuroblastoma cell lines were exposed to a 209-compound library in the absence and presence of venetoclax to identify compounds that were more effective in the venetoclax-resistant cell lines under venetoclax pressure. Top hits were further validated in combination with venetoclax using BCL-2–dependent neuroblastoma model systems. Overall, high-throughput drug screening identified the MDM2 inhibitor idasanutlin as a promising resensitizing agent for venetoclax-resistant neuroblastoma cell lines. Idasanutlin treatment induced BAX-mediated apoptosis in venetoclax-resistant neuroblastoma cells in the presence of venetoclax, whereas it caused p21-mediated growth arrest in control cells. In vivo combination treatment showed tumor regression and superior efficacy over single-agent therapies in a BCL-2–dependent neuroblastoma cell line xenograft and a patient-derived xenograft. However, xenografts less dependent on BCL-2 were not sensitive to venetoclax–idasanutlin combination therapy. This study demonstrates that idasanutlin can overcome resistance to the BCL-2 inhibitor venetoclax in preclinical neuroblastoma model systems, which supports clinical development of a treatment strategy combining the two therapies.
Novel TGFβ Inhibitors Ameliorate Oral Squamous Cell Carcinoma Progression and Improve the Antitumor Immune Response of Anti–PD-L1 Immunotherapy
Authors: Ludwig Nils , Wieteska Łukasz , Hinck Cynthia S. , Yerneni Saigopalakrishna S. , Azambuja Juliana H. , Bauer Richard J. , Reichert Torsten E. , Hinck Andrew P. , Whiteside Theresa L.
Published: April 2021

TGFβ is a key regulator of oral squamous cell carcinoma (OSCC) progression, and its potential role as a therapeutic target has been investigated with a limited success. This study evaluates two novel TGFβ inhibitors as mono or combinatorial therapy with anti–PD-L1 antibodies (α-PD-L1 Ab) in a murine OSCC model. Immunocompetent C57BL/6 mice bearing malignant oral lesions induced by 4-nitroquinoline 1-oxide (4-NQO) were treated for 4 weeks with TGFβ inhibitors mRER (i.p., 50 μg/d) or mmTGFβ2-7m (10 μg/d delivered by osmotic pumps) alone or in combination with α-PD-L1 Abs (7× i.p. of 100 μg/72 h). Tumor progression and body weight were monitored. Levels of bioactive TGFβ in serum were quantified using a TGFβ bioassay. Tissues were analyzed by immunohistology and flow cytometry. Therapy with mRER or mmTGFβ2-7m reduced tumor burden (P < 0.05) and decreased body weight loss compared with controls. In inhibitor-treated mice, levels of TGFβ in tumor tissue and serum were reduced (P < 0.05), whereas they increased with tumor progression in controls. Both inhibitors enhanced CD8+ T-cell infiltration into tumors and mRER reduced levels of myeloid-derived suppressor cells (P < 0.001). In combination with α-PD-L1 Abs, tumor burden was not further reduced; however, mmTGFβ2-7m further reduced weight loss (P < 0.05). The collagen-rich stroma was reduced by using combinatorial TGFβ/PD-L1 therapies (P < 0.05), enabling an accelerated lymphocyte infiltration into tumor tissues. The blockade of TGFβ signaling by mRER or mmTGFβ2-7m ameliorated in vivo progression of established murine OSCC. The inhibitors promoted antitumor immune responses, alone and in combination with α-PD-L1 Abs.
Abstract IA-005: Base excision repair and cancer
Authors: Sweasy Joann B.
Published: April 2021

The Base Excision Repair (BER) machinery has evolved to process DNA bases damaged by reactive oxygen and nitrogen species as well as base lesions induced by alkylating agents. Deficient repair of damaged bases results in mutagenesis and genomic instability, whereas efficient repair of alkylating agents used to treat tumors leads to drug resistance. Human genome sequencing studies show that there are hundreds of germline variants in BER genes that are likely to encode proteins with altered function. This presentation will focus on the mechanistic insights gained from our characterization of some of these germline BER variants. We have discovered that variants in DNA glycosylase and DNA polymerase genes induce genomic instability and cellular transformation when expressed in non-transformed cells. These phenotypes result from defective or aberrant enzymatic function. Our results suggest that germline variants of BER genes likely increase risk for cancer and other diseases.

Citation Format: Joann B. Sweasy. Base excision repair and cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-005.
Abstract IA-007: Exploiting DNA repair defects in head and neck squamous cell carcinoma
Authors: Vens Conchita
Published: April 2021

DNA damage repair pathways govern genomic integrity and determine cellular sensitivities to radiation and chemotherapeutic agents. Recent genetic studies highlight the identification of an increasing number of DNA repair gene defects in many different cancer types. DNA damage response and repair inhibitors on the other hand provide opportunities to exploit such defects inherent to cancer cells. Combined with radiotherapy they are highly effective radiosensitizers that show some tumor specificity in that they cause greater radiation dose enhancement in cells with repair defects. To optimize such potent combinations, robust and sensitive biomarkers are needed to 1) assess effectivity and guide clinical trial designs and 2) to identify repair defects in individual patients. Radiotherapy is a mainstay in the treatment of advanced HPV-negative head and neck squamous cell carcinoma (HNSCC). There is a need for improved treatment options in this patient population. Indicating particular crosslink repair sensitivity and frequent cancer cell repair defects, cumulative cisplatin dose is an important factor in determining patient outcomes after chemoradiotherapy. Indeed, preclinical and genetic data highlight the frequent manifestation of DNA crosslink repair defects in HNSCC. Genetic biomarkers have therefore been generated and tested to support the identification of patients in need for novel treatment options and of crosslink repair defects in HNSCC for combination with PARP inhibitors.

Citation Format: Conchita Vens. Exploiting DNA repair defects in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-007.
Abstract IA-009: TGFβ regulation of DNA repair across cancer types predicts response to genotoxic therapies
Authors: Barcellos-Hoff Mary Helen
Published: April 2021

Transforming growth factor β (TGFβ) has a long-standing but poorly understood role in DNA repair and genomic stability. We recently showed that inhibition or loss of TGFβ signaling decreases homologous recombination and increases use of alternative end-joining (alt-EJ), an error-prone DNA repair process (Liu et al. Clin. Ca. Res. 2018). New experimental studies show that TGFβ actively suppresses genes involved in alt-EJ. Because many cancers have compromised TGFβ signaling, we determined the mechanistic implications of the relationship between TGFβ and alt-EJ using gene expression signatures by analyzing their association with outcomes in the Cancer Genome Atlas (TCGA). These studies show that the anti-correlation of TGFβ and alt-EJ regardless of tumor type is significantly associated with survival in patients treated with radiotherapy or chemoradiation. Prospective identification of patients in which TGFβ opposes effective genotoxic therapy will expand the potential therapeutic scope of TGFβ inhibitors.

Citation Format: Mary Helen Barcellos-Hoff. TGFβ regulation of DNA repair across cancer types predicts response to genotoxic therapies [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-009.
Abstract IA-011: Translation to clinical trials: Are we shooting the right arrows at the target?
Authors: Sharma Ricky A.
Published: April 2021

Dependent on the stage of the cancer, 25-40% of patients require curative or palliative radiotherapy as part of their primary care treatment. The DNA Damage response (DDR) pathways have been a major area of interest for drug development as tumors often harbor mutations in the DDR pathways. The development of new DDR inhibitors offers wide-ranging opportunities to combine DDR inhibition with radiation therapy. Emerging evidence also supports the use of DDR inhibitors to promote immune stimulatory effects of radiation therapy by further activating the DNA sensing cGAS-STING pathway. DDR inhibitors in combination with RT have been shown to alter PDL-1 expression and have also been linked to modulating cytokine expression to alter the tumor microenvironment. This should be considered in the context of over 300 clinical trials ongoing which are combining immunotherapy with radiotherapy and important clinical studies of this combination therapy which have been published in patients with lung cancer. Significant progress is being made in understanding new drug-radiotherapy combinations and advancing them towards the clinic.

Citation Format: Ricky A. Sharma. Translation to clinical trials: Are we shooting the right arrows at the target? [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-011.
Abstract IA-016: Metabolic deregulation drives a redox vulnerability in pancreatic cancer
Authors: Koritzinsky Marianne , Jain Pallavi , Dvorkin-Gheva Anna , Malbeteau Lucie , Dhavarasa Piriththiv , Brown Kevin R. , Jang Gun Ho , Vora Parth , Notta Faiyaz , Moffat Jason , Boutros Paul C.
Published: April 2021

Pancreatic ductal adenocarcinoma (PDAC) is an almost universally fatal malignancy and there is an urgent need for new therapeutic targets. PDAC cells harbor genetic alterations and display metabolic changes that render them vulnerable to perturbations in redox homeostasis. Peroxiredoxin 4 (PRDX4) supports redox homeostasis by metabolizing H2O2 in the endoplasmic reticulum (ER). Based on functional genomics, we found that PDAC cell lines are dependent on PRDX4 for their growth and survival. We validated this dependency in established and primary PDAC cells, as well as in 3D models and orthotopic xenografts. PRDX4 depletion led to increased levels of reactive oxygen species (ROS). Tumor cells are exposed to fluctuating oxygen levels, which are known to augment ROS production. In line with this, PRDX4 addiction was also exacerbated in cells exposed to hypoxia and reoxygenation. Cell death induced by PRDX4 depletion was accompanied by DNA damage and a DNA-PKcs-governed DNA damage response. As such, PRDX4 depletion also sensitized cells and tumors to ionizing radiation. The source of ROS that created a dependency on PRDX4 was attributed to NADPH oxidase 4 (NOX4), which localizes to the ER membrane. The functional requirement for PRDX4 was correlated with cellular NADPH levels across different models of PDAC and could be rescued by depletion of NOX4 or NADPH. As such, this study has identified NOX4 as a link between metabolic deregulation and ER-specific redox vulnerability in PDAC. Since PRDX4 is not an essential gene in normal tissues, our work also suggests that PRDX4 represents a novel therapeutic target for pancreatic cancer that may be particularly potent in combination with radiotherapy.

Citation Format: Marianne Koritzinsky, Pallavi Jain, Anna Dvorkin-Gheva, Lucie Malbeteau, Piriththiv Dhavarasa, Kevin R. Brown, Gun Ho Jang, Parth Vora, Faiyaz Notta, Jason Moffat, Paul C. Boutros. Metabolic deregulation drives a redox vulnerability in pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-016.
Abstract IA-022: Lysine 68 acetylation directs MnSOD as a tetrameric detoxification complex versus a monomeric tumor promoter
Authors: Gius David
Published: April 2021

Manganese superoxide dismutase (MnSOD) functions as a tumor suppressor; however, once tumorigenesis occurs, clinical data suggest MnSOD levels correlate with more aggressive human tumors, implying a potential dual function of MnSOD in the regulation of metabolism. Here we show, using in vitro transformation and xenograft growth assays that the MnSOD-K68 acetylation (Ac) mimic mutant (MnSODK68Q) functions as a tumor promoter. Interestingly, in various breast cancer and primary cell types the expression of MnSODK68Q is accompanied with a change of MnSOD’s stoichiometry from a known homotetramer complex to a monomeric form. Biochemical experiments using the MnSOD-K68Q Ac-mimic, or physically K68-Ac (MnSOD-K68-Ac), suggest that these monomers function as a peroxidase, distinct from the established MnSOD superoxide dismutase activity. MnSODK68Q expressing cells exhibit resistance to tamoxifen (Tam) and cells selected for Tam resistance exhibited increased K68-Ac and monomeric MnSOD. These results suggest a MnSOD-K68-Ac metabolic pathway for Tam resistance, carcinogenesis and tumor progression.

Citation Format: David Gius. Lysine 68 acetylation directs MnSOD as a tetrameric detoxification complex versus a monomeric tumor promoter [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-022.
Abstract PO-004: A phase I clinical trial of dose-escalated metabolic therapy combined with concomitant radiation therapy in high-grade glioma
Authors: Lawrence Yaacov , Porper Keren , Shpatz Yael , Amit Uri , Symon Zvi , Zach Leor
Published: April 2021

Background Animal brain-tumor models have demonstrated a synergistic interaction between radiation therapy and a ketogenic diet (KD). Metformin has in-vitro anti-cancer activity, through AMPK activation and mTOR inhibition. We hypothesized that metabolic stress (moderate hypoglycemia) would enhance the anti-tumor efficacy of concurrent DNA damage. We further hypothesized that concurrent metformin would decrease insulin resistance and consequently elevate ketone blood level. We performed a formal prospective phase I dose-escalation trial to assess the tolerability and feasibility of this approach. Methods A prospective single-institution phase I clinical trial of combined metabolic therapy and radiotherapy. Radiotherapy was either 60Gy over six weeks or 35Gy over two weeks for newly diagnosed and recurrent gliomas, respectively. The dietary intervention consisted of a KD supplemented with medium chain triglycerides (MCT). There were three cohorts 1) dietary intervention alone, 2) low-dose metformin (850mg twice-daily) combined with dietary intervention and 3) high-dose metformin (850mg three-times daily) combined with dietary intervention. Statistics: The prediction of blood ketones levels was performed using a mixed-model univariate analysis methodology. Clinicaltrials.gov NCT02149459. Results A total of 13 patients were accrued, median age 61 years, of whom 6 had newly diagnosed and 7 with recurrent disease. All completed radiation therapy; 5 patients stopped the metabolic intervention early. Metformin 850mg three-times daily was poorly tolerated. There were no grade 4/5 adverse events. Median levels of β-hydroxybutyrate increased from 0.09 mmol/l at baseline to 0.59 mmol/l during the trial (p=0.006). Ketone levels were associated with dietary factors (ketogenic ratio, p < 0.001), use of metformin (p = 0.02) and low insulin levels (p = 0.002). Median progression free survival was 10 months for newly diagnosed disease and 4 months for recurrent disease. Conclusions The intervention was fairly well tolerated. Metformin use and dietary intake were associated with higher serum ketone levels. The recommended phase II dose is the 8 weeks of a KD combined with 850mg metformin twice daily. The trial was supported by the EU FP7 Marie Curie program FP7-MC-CIG 303795, and the Rosetrees Trust. The MCT oil was provided by Nutricia, Netherlands.

Citation Format: Yaacov Lawrence, Keren Porper, Yael Shpatz, Uri Amit, Zvi Symon, Leor Zach. A phase I clinical trial of dose-escalated metabolic therapy combined with concomitant radiation therapy in high-grade glioma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-004.
Abstract PO-008: Mechanistic and therapeutic links between purine biosynthesis and DNA damage in glioblastoma
Authors: Scott Andrew J. , Zhou Weihua , Wilder-Romans Kari , Andren Anthony C. , Zhang Li , Umemura Yoshie , Qi Nathan , Lawrence Theodore S. , Lyssiotis Costas A. , Wahl Daniel R
Published: April 2021

Glioblastoma (GBM) is the most common and aggressive adult brain cancer. Radiation therapy (RT) is a critical treatment modality, and development of RT resistance is the predominant cause of recurrence and mortality in GBM patients. Using cell line models as well as patient-derived xenografts and neurospheres in orthotopic brain tumor models, we have identified increased rates and dependence upon de novo purine biosynthesis as a hallmark of GBM RT resistance. More recently, we have discovered that radiation treatment acutely stimulates flux through de novo purine synthesis in cell line and neurosphere models of GBM. This RT-induced increase in de novo purine synthesis is dependent on signaling through the DNA damage response and thus appears to be an adaptive mechanism to supply purines to repair radiation-induced DNA damage. To determine whether this regulatory mechanism also exists in vivo, we have used advanced metabolomic and metabolic tracing techniques with 13C-labeled glucose and 15N-labeled glutamine in mice bearing RT-resistant GBM patient-derived orthotopic brain tumors. We found that that orthotopic GBM PDXs had elevated activity of de novo purine synthesis that increased further after RT, while normal cortex had little activity even after RT. These observations have therapeutic relevance, as targeting this metabolic pathway with the FDA-approved purine biosynthesis inhibitor mycophenolate mofetil (MMF) overcomes GBM radiation resistance in mouse models in vivo. The lack of de novo purine synthesis in normal cortex suggests that targeting this pathway may be tumor specific. Collectively our data suggest that de novo synthesis of purines mediates RT resistance in GBM and that treatment of brain tumors with MMF in combination with RT may be a promising therapeutic strategy in patients.

Citation Format: Andrew J. Scott, Weihua Zhou, Kari Wilder-Romans, Anthony C. Andren, Li Zhang, Yoshie Umemura, Nathan Qi, Theodore S. Lawrence, Costas A. Lyssiotis, Daniel R Wahl. Mechanistic and therapeutic links between purine biosynthesis and DNA damage in glioblastoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-008.
Abstract PO-052: Radiation regimen and timing of PD1 blockade critically influence response to combination therapy in head and neck squamous cell carcinoma
Authors: Verma Aparajita , Habitzruther Michael , Attwood Kristopher , Seshadri Mukund
Published: April 2021

Head and neck squamous cell carcinoma (HNSCC) constitute the sixth most common cancer worldwide, with a 5-year survival of less than 50% for advanced HNSCC patients. Radiation therapy (RT) is widely used in the treatment of HNSCC patients. Preclinical studies have shown that RT can trigger immune mediated response that potentiates tumor regression. However, the use of RT in combination with immune checkpoint inhibitor, specifically programmed death protein-1 blockade (αPD-1), has not been extensively examined in HNSCC. In vitro studies in our laboratory revealed that radiation increased PD-L1 expression in HNSCC tumor cells in a dose-dependent manner. Based on this observation, we hypothesized that the efficacy of RT and αPD-1 therapy would be critically influenced by the timing of αPD-1 of administration. To test this hypothesis, we conducted a preclinical study using a novel orthotopic immunocompetent mouse model of HNSCC (RPMOC1). Tumor bearing mice were randomized into the following arms: RT (single dose 10 Gy), fractionated RT (fRT- 2Gy x 5), RT prior to αPD-1(200 μg), RT post αPD-1, fRT prior to αPD-1 and fRT post αPD-1. Non-invasive magnetic resonance imaging (MRI) was used to monitor tumor response to therapy. All treatment regimens were well tolerated and did not result in weight loss during the experiment. The most potent tumor growth inhibition was observed in the RT (10 Gy) and αPD-1 combination therapy group. RT given either before or after αPD-1 therapy resulted in a significant decrease in tumor volumes (p<0.05) compared to other groups. Combination therapy with fractionated radiation did not show improved response compared to monotherapy. Overall, our observations indicate that tumor response to combined radiation and immunotherapy is critically influenced by the radiation regimen and timing of PD1 blockade in HNSCC.

Citation Format: Aparajita Verma, Michael Habitzruther, Kristopher Attwood, Mukund Seshadri. Radiation regimen and timing of PD1 blockade critically influence response to combination therapy in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-052.
Abstract PO-061: Deciphering radiation resistance in head and neck cancer using patient derived organoids
Authors: Vincent-Chong Vui King , Gluck Christian , Hershberger Pamela A. , Sinha Satrajit , Seshadri Mukund
Published: April 2021

Radiation therapy (RT) is an integral component of the standard of care for patients with head and neck squamous cell carcinoma (HNSCC). While advances in radiation delivery methods have led to improved outcomes, radioresistance poses a significant therapeutic challenge and a major cause of poor prognosis in this patient population. To date, a majority of studies investigating mechanisms of radioresistance have employed in vitro monolayer cell culture models that lack the heterogeneity and cell-extracellular matrix interactions. To overcome this limitation, we established and credentialed a panel of 3D patient-derived organoid (PDO) models of HNSCC to identify molecular signatures and signaling pathways that contribute to radiation resistance. A total of 7 PDOs were established from surgical HNSCC specimens and credentialed using a combination of histologic/immunohistochemical evaluation (H&E, cytokeratin, p16), genotyping (HPV), whole exome sequencing (WES) and RNA sequencing analysis. Radiation response of the PDO panel was also examined and assessed for concordance with patient response and PDOs were ranked based on their radiosensitivity and bioinformatic analysis was performed on radiosensitive and radioresistance PDOs to identify molecular pathways associated with resistance. All PDOs retained the histology, p16/HPV status and mutational landscape (p53, HLA-A) of donor patient tissues. Radiation response of PDOs showed excellent (100%) concordance with patient responses (n=5 with history of radiation treatment). RNA-seq revealed identified pathways associated with epithelial mesenchymal transition (IGFBP2, TIMP1, TIMP2, LAMA3, LOXL1), NOTCH signaling (NOTCH1, HES1, FZD1, FZD5, DTX1, NOTCH3, FZD7), E2F targets and G2M checkpoint signaling (MCM2, MCM7, MCM4, PCNA) and the p53 pathway (SFN, NDRG1, ALOX15B). Collectively, our findings illustrate the translational utility of PDOs as a robust platform in identifying potential therapeutic targets that could overcome radiation resistance in HNSCC. Ongoing studies are evaluating the potential of PDOs to serve as a screening platform to identify radiosensitizers through repurposing of FDA-approved drugs to facilitate rapid clinical translation.

Citation Format: Vui King Vincent-Chong, Christian Gluck, Pamela A. Hershberger, Satrajit Sinha, Mukund Seshadri. Deciphering radiation resistance in head and neck cancer using patient derived organoids [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-061.
Abstract PO-065: ATRXLoss and IDH1R132H impair self-renewal of glioma stem cells after proton radiotherapy
Authors: Garces Angel A. , Bronk Lawrence , Bhat Krishna P.L. , Grosshans David R.
Published: April 2021

Background: Glioblastoma Multiforme (GBM-Grade IV) is the most aggressive form of glioma in the USA carrying only a 15-month median survival time. IDH1R132H is an early onset mutation present in 70-80% of low grade gliomas (LGG-Grade I and II) and secondary GBM patients that causes intracellular oxidative stress and impairment of post-radiation DNA damage repair (DDR) via Homologous Recombination (HR). Although IDH1R132H is associated with improved patient survival and clinical response to chemotherapy, astrocytoma (LGG) patients specifically also harbor ATRXLoss, a genetic alteration that inactivates the ATRX chromatin remodeling protein and impairs DDR via non-homologous end joining (NHEJ). Importantly, the recent discovery of glioma stem cells (GSCs), a subpopulation of chemoradioresistant, self-renewable, tumor initiating cells known to promote tumor recurrence, presents a new target for therapeutic intervention. However, the mechanisms by which IDH1R132H and ATRXLoss contribute to GSC sensitivity to proton radiotherapy (PRT), a more tumor specific and cytotoxic form of radiation therapy than conventional X-rays (XRT), is not well understood. We hypothesize that both IDH1R132H and ATRXLoss contribute to the impairment of GSC self-renewal after PRT, but not after XRT. Methods: Isogenic MGG18-IDH1WT, MGG18-IDH1R132H, TS543-ATRXWT, and TS543-ATRXLoss patient derived glioma cells were cultured as neurospheres and treated with 3-6 Gy of XRT or PRT. GSC self-renewal, based on neurosphere formation frequency, was quantified using extreme limiting dilution analysis (ELDA). Results: TS543-ATRXLoss significantly inhibited GSC self-renewal over TS543-ATRXWT when subject to PRT (Pairwise Testing Pr(>χ2)<0.01). However, TS543-ATRXWT displayed lower GSC self-renewal compared to TS543-ATRXLoss when subject to XRT (Pr(>χ2)<0.0001). Interestingly, similar results were found in the isogenic MGG18 cell lines. MGG18-IDH1R132H displayed higher radiosensitivity to PRT (Pr(>χ2)<0.05) while MGG18-IDH1WT displayed higher radiosensitivity to XRT (Pr(>χ2)<0.01), as defined by GSC self-renewal. Conclusions: We conclude that ATRXLoss and IDH1R132H both substantially contribute to PRT sensitivity in GSCs, thereby supporting the benefits of PRT for astrocytoma patients. Our future experiments will further elucidate the biological mechanisms by which ATRXLoss and IDH1R132H confer PRT sensitivity, especially via dsDNA damage and apoptosis.

Citation Format: Angel A. Garces, Lawrence Bronk, Krishna P.L. Bhat, David R. Grosshans. ATRXLoss and IDH1R132H impair self-renewal of glioma stem cells after proton radiotherapy [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-065.
Abstract PR-002: SIRT2 promotes BRCA1-BARD1 heterodimerization through deacetylation
Authors: Minten Elizabeth V. , Kappor-Vazirani Priya , Li Chunyang , Zhang Hui , Balakrishnan Kamakshi , Yu David S.
Published: April 2021

The breast cancer type I susceptibility protein (BRCA1) and BRCA1-associated RING domain protein I (BARD1) heterodimer promotes genome integrity through pleiotropic functions, including DNA double-strand break (DSB) repair by homologous recombination (HR). BRCA1-BARD1 heterodimerization is required for their mutual stability, HR function, and role in tumor suppression; however, the upstream signaling events governing BRCA1-BARD1 heterodimerization are unclear. Here, we show that SIRT2, a sirtuin deacetylase and breast tumor suppressor, promotes BRCA1-BARD1 heterodimerization through deacetylation. SIRT2 complexes with BRCA1-BARD1 and deacetylates conserved lysines in the BARD1 RING domain, interfacing BRCA1, which promotes BRCA1-BARD1 heterodimerization and consequently BRCA1-BARD1 stability, nuclear retention, and localization to DNA damage sites, as well as efficient HR. Our findings define a mechanism for regulation of BRCA1-BARD1 heterodimerization through SIRT2 deacetylation, elucidating a critical upstream signaling event directing BRCA1-BARD1 heterodimerization, which facilitates HR and tumor suppression, and delineating a role for SIRT2 in directing DSB repair by HR.

Citation Format: Elizabeth V. Minten, Priya Kappor-Vazirani, Chunyang Li, Hui Zhang, Kamakshi Balakrishnan, David S. Yu. SIRT2 promotes BRCA1-BARD1 heterodimerization through deacetylation [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PR-002.
Abstract PR-004: Radiation modulates hepatic siphoning of T cells to improve immunotherapy efficacy
Authors: Green Michael , Yu Jiali , Li Shasha , Lawrence Theodore S. , Zou Weiping
Published: April 2021

It is not well established which site(s) in a metastatic patients should be targeted with radiotherapy to elicit responses to immunotherapy. While cancer frequently metastasizes to the liver, it is unknown if liver immune tolerance mechanisms contribute to cancer outcomes. We have found that that liver metastases diminish immunotherapy efficacy systemically in patients and preclinical models. We and others have shown that patients with liver metastases derive limited benefit from immune checkpoint inhibitors. In preclinical models, we show that liver metastases siphon activated CD8+ T cells from systemic circulation and induce their apoptosis within the liver. Consequently, liver metastases create a systemic immune desert. Similarly, patients with liver metastases have reduced adaptive immune responses. In preclinical models, liver-directed radiotherapy eliminates hepatic siphoning of T cells. Thus, liver metastases cause acquired immunotherapy resistance through CD8+ T cell deletion, and the combination of liver-directed radiotherapy and immunotherapy could promote systemic anti-tumor immunity.

Citation Format: Michael Green, Jiali Yu, Shasha Li, Theodore S. Lawrence, Weiping Zou. Radiation modulates hepatic siphoning of T cells to improve immunotherapy efficacy [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PR-004.
The Influence of Vitamin D on Mammographic Density: Results from CALGB 70806 (Alliance) a Randomized Clinical Trial
Authors: Wood Marie E. , Liu Heshan , Storrick Elizabeth , Zahrieh David , Le-Petross H. Carisa , Jung Sin-Ho , Zekan Patricia , Kemeny M. Margaret , Charlamb Jayne R. , Wang Lili X. , Unzeitig Gary W. , Johnson Candace S. , Garber Judy E. , Marshall James R. , Bedrosian Isabelle
Published: April 2021

Current therapies for breast cancer prevention only prevent estrogen receptor positive (ER+) disease and toxicity limits use of these agents. Vitamin D is a potential prevention therapy for both ER+ and ER− disease and is safe with few side effects. This study evaluates the effect of 1-year of vitamin D supplementation on mammographic density (MD), a biomarker of breast cancer risk in a multicenter randomized controlled trial. Premenopausal women with ≥25% MD and no history of cancer were randomly assigned to 2,000 international units (IU) of vitamin D or placebo orally daily for 1 year. Change in percent MD was evaluated using Cumulus software after all participants completed treatment. Three hundred women enrolled between January 2011 and December 2013 with a mean age of 43 and diverse ethnicity [14% Hispanic, 12% African American (AA)]. Supplementation significantly increased vitamin D levels compared with placebo (14.5 ng/mL vs. −1.6 ng/mL; P < 0.0001) with all participants on the vitamin D arm achieving vitamin D sufficiency at 12 months. Vitamin D was safe and well tolerated. After adjustment for baseline MD, the mean between-arm difference (vitamin D vs. placebo) at 1 year was −0.75 (−0.26, 1.76; P = 0.56). A greater effect was seen for women with ≥50% MD and AA women, although neither reached significance. This randomized controlled trial demonstrated significant improvement in vitamin D levels with 2,000 IU for 1 year, with 100% of supplemented women achieving sufficiency. However, a null effect was seen regarding change in MD for premenopausal women (the primary outcome of the study).

Prevention Relevance:

Current therapies for breast cancer prevention only prevent estrogen receptor positive (ER+) disease and are underutilized due to toxicity and side effects. Vitamin D is a potential prevention therapy for both ER+ and ER− disease and is safe with few side effects.
Protective and Anti-Aging Effects of 5 Cosmeceutical Peptide Mixtures on Hydrogen Peroxide-Induced Premature Senescence in Human Skin Fibroblasts
Authors: Wu Yun , Cao Kun , Zhang Wei , Zhang Guangxian , Zhou Maojun
Published: April 2021

Skin aging usually leads to the excessive deterioration of the dermal extracellular matrix, loss of antimicrobial function, loss of skin barrier function, and a series of inflammatory processes. Bioactive peptides have been widely used in cosmetics due to their protective effects on skin and efficient absorption. Combination of different peptides may lead to synergistic or antagonistic effects, so different formulas need to be designed and tested properly. In this study, 5 functional cosmeceutical peptides were tested on their individual and mixed activities to detect a suitable anti-aging and protective formula from our experiments. After the individual activity test, the optimal concentration is 200 μg/mL of carnosine for the superoxide dismutase (SOD) activity, 200 μg/mL of GHK peptide for the hydroxyproline (HYP) content activity, 100 μg/mL of acetyl tetrapeptide-5 for the angiotensin-converting enzyme 1 activity, 400 μg/mL of hexapeptide-11 for the HYP content activity, and 400 μg/mL of acetyl hexapeptide-3 for the catecholamine content activity. According to the optimal concentration of these 5 cosmeceutical peptides, 6 formulations of peptide mixtures were designed and tested for their anti-aging activities and protective effects against hydrogen peroxide-induced premature senescence in human skin fibroblasts. One of the cosmeceutical peptide mixtures (carnosine + acetyl tetrapeptide-5 + hexapeptide-11 + acetyl hexapeptide-3) significantly reduced the intracellular malondialdehyde and hydroxyl free radical contents and increased the HYP and human elastin contents as well as the enzymatic activities of SOD and glutathione peroxidase. Our study suggests that this formula of cosmeceutical peptide mixtures could be a promising agent for use in anti-aging and protective cosmetics.
Variable Learning Curve of Basic Rigid Bronchoscopy in Trainees
Authors: Mahmood Kamran , Wahidi Momen M. , Shepherd Ray Wes , Argento A. Christine , Yarmus Lonny B. , Lee Hans , Shojaee Samira , Berkowitz David M. , Van Nostrand Keriann , Lamb Carla R. , Shofer Scott L. , Gao Junheng , Davoudi Mohsen
Published: April 2021

Background: Despite increased use of rigid bronchoscopy (RB) for therapeutic indications and recommendations from professional societies to use performance-based competency, an assessment tool has not been utilized to measure the competency of trainees to perform RB in clinical settings. Objectives: The aim of the study was to evaluate a previously developed assessment tool – Rigid Bronchoscopy Tool for Assessment of Skills and Competence (RIGID-TASC) – for determining the RB learning curve of interventional pulmonary (IP) trainees in the clinical setting and explore the variability of learning curve of trainees. Methods: IP fellows at 4 institutions were enrolled. After preclinical simulation training, all RBs performed in patients were scored by faculty using RIGID-TASC until competency threshold was achieved. Competency threshold was defined as unassisted RB intubation and navigation through the central airways on 3 consecutive patients at the first attempt with a minimum score of 89. A regression-based model was devised to construct and compare the learning curves. Results: Twelve IP fellows performed 178 RBs. Trainees reached the competency threshold between 5 and 24 RBs, with a median of 15 RBs (95% CI, 6–21). There were differences among trainees in learning curve parameters including starting point, slope, and inflection point, as demonstrated by the curve-fitting model. Subtasks that required the highest number of procedures (median = 10) to gain competency included ability to intubate at the first attempt and intubation time of <60 s. Conclusions: Trainees acquire RB skills at a variable pace, and RIGID-TASC can be used to assess learning curve of IP trainees in clinical settings.
Comparison of Follow-Up Length-Matched Single-Center Myelomeningocele Postnatal Closure Cohort to the Management of Myelomeningocele Study (MOMS) Trial Results
Authors: Weaver Kristin J. , McDowell Michael M. , White Michael D. , Tempel Zachary J. , Zwagerman Nathan T. , Deibert Christopher P. , Bonfield Christopher M. , Johnson Stephen , Greene Stephanie
Published: April 2021

Objective: We sought to compare our large single-institution cohort of postnatal myelomeningocele closure to the 2 arms of the Management of Myelomeningocele Study (MOMS) trial at the designated trial time points, as well as assess outcomes at long-term follow-up among our postnatal cohort. Methods: A single-institutional retrospective review of myelomeningocele cases presenting from 1995 to 2015 at Children’s Hospital of Pittsburgh was performed. We compared outcomes at 12 and 30 months to both arms of the MOMS trial and compared our cohort’s outcomes at those designated time points to our long-term outcomes. Univariate statistical analysis was performed as appropriate. Results: One-hundred sixty-three patients were included in this study. All patients had at least 2-year follow-up, with a mean follow-up of 10 years (range 2–20 years). There was no difference in the overall distribution of anatomic level of defect. Compared to our cohort, the prenatal cohort had a higher rate of tethering at 12 months of age, 8 versus 1.8%. Conversely, the Chiari II decompression rate was higher in our cohort (10.4 vs. 1.0%). At 30 months, the prenatal cohort had a higher rate of independent ambulation, but our cohort demonstrated the highest rate of ambulation with or without assistive devices among the 3 groups. When comparing our cohort at these early time points to our long-term follow-up data, our cohort’s ambulatory function decreased from 84 to 66%, and the rate of detethering surgery increased almost 10-fold. Conclusions: This study demonstrated that overall ambulation and anatomic-functional level were significantly better among our large postnatal cohort, as well as having significantly fewer complications to both fetus and mother, when compared to the postnatal cohort of the MOMS trial. Our finding that ambulatory ability declined significantly with age in this patient population is worrisome for the long-term outcomes of the MOMS cohorts, especially given the high rates of cord tethering at early ages within the prenatal cohort. These findings suggest that the perceived benefits of prenatal closure over postnatal closure may not be as substantial as presented in the original trial, with the durability of results still remaining a concern.
Prevention of Iodinated Contrast Media-Induced Hyperthyroidism in Patients with Euthyroid Goiter
Authors: Pelewicz Katarzyna , Wolny Rafał , Bednarczuk Tomasz , Miśkiewicz Piotr
Published: April 2021

Introduction: Iodinated contrast media (ICM)-induced hyperthyroidism is an underestimated, potentially severe condition; however, its prevention has not been sufficiently investigated. The aim of this study was to evaluate the influence of ICM on thyroid status, the advantages of prophylactic therapy for iodine-induced hyperthyroidism (IIH) in patients with euthyroid goiter and cardiovascular comorbidities, and the association between the incidence of IIH and thyroid volume. Methods: Thirty-six euthyroid patients undergoing procedures involving ICM administration were divided into 2 groups: the first group (n = 13) received prophylactic treatment with thiamazole or thiamazole combined with sodium perchlorate during ICM exposure; the second group (n = 23) did not receive prophylaxis. Thyroid-stimulating hormone levels were evaluated before and after ICM, and thyroid hormone levels were assessed after ICM at different points in time. The morphology of the thyroid was evaluated by ultrasonography. Results: Twenty-one patients (58%) developed hyperthyroidism after ICM. Hyperthyroidism was observed more frequently in the group without prophylactic treatment than in the group with prophylaxis (65 vs. 15%, respectively; p = 0.006). No cases of overt hyperthyroidism were observed in the group receiving thiamazole with sodium perchlorate. IIH persisted for a median time of 52.5 days. Larger thyroid volume was associated with a significantly higher occurrence of ICM-induced hyperthyroidism (p = 0.04). Conclusions: Patients with euthyroid goiter receiving ICM are at risk of developing hyperthyroidism. The occurrence of hyperthyroidism after ICM in euthyroid patients with goiter is higher in those with larger thyroid volume. The frequency of ICM-induced hyperthyroidism in euthyroid patients with goiter is lower in those receiving prophylactic therapy with thiamazole in monotherapy or in combination with sodium perchlorate than in those not receiving prophylactic treatment.
A Before-and-After Study of Evidence-Based Recommendations for On-Call Bronchoscopy
Authors: Duesberg Christoph Benedikt , Valtin Christina , Fuge Jan , Logemann Frank , Fuehner Thomas , Welte Tobias , Gottlieb Jens
Published: April 2021

Background: Bronchoscopy is widely used and regarded as standard of care in most intensive care units (ICUs). Data concerning recommendations for on-call bronchoscopy are lacking. Objectives: Evaluation of recommendations, complications, and outcome of on-call bronchoscopies. Method: A retrospective single-centre analysis was conducted in a large university hospital. All on-call bronchoscopies performed outside normal working hours in the year before (period 1) and after (period 2) establishing a catalogue of recommendations for indications of on-call bronchoscopy on November 1, 2016, were included. Results: Overall, 924 bronchoscopies in 538 patients were analysed. A relative reduction of 83.6% from 794 bronchoscopies in 432 patients (1.84 per patient) during period 1 to 130 in 107 patients (1.21 per patient) during period 2 was observed. Most bronchoscopies (812/924, 87.9%) were performed in ICUs, and 416 patients (77.3%) were intubated. Bronchoscopies for excessive secretions decreased significantly during period 2. Fifty-three of 130 bronchoscopies (40.8%) fulfilled the specified recommendations during period 2, in comparison with 16.8% in period 1 (p < 0.001). Complications were recorded in 58 of 924 procedures (6.3%) and were more frequent in period 2, especially moderate bleeding. In-hospital mortality of patients undergoing on-call bronchoscopy did not differ between periods and was 28.7 and 30.2% in periods 1 and 2, respectively. Conclusion: The introduction of recommendations for on-call bronchoscopy led to a significant decline of on-call bronchoscopies without negatively affecting outcome. More evidence is needed in on-call bronchoscopy, especially for ICU patients with intrinsic higher complication rates.