Genomic analysis of human brain metastases treated with stereotactic radiosurgery reveals unique signature based on treatment failure

Stereotactic radiosurgery (SRS) has been shown to be efficacious for the treatment of limited brain metastasis (BM); however, the effects of SRS on human brain metastases have yet to be studied. We performed genomic analysis on resected brain metastases from patients whose resected lesion was previously treated with SRS. Our analyses demonstrated for the first time that patients possess a distinct genomic signature based on type of treatment failure including local failure, leptomeningeal spread, and radio-necrosis. Examination of the center and peripheral edge of the tumors treated with SRS indicated differential DNA damage distribution and an enrichment for tumor suppressor mutations and DNA damage repair pathways along the peripheral edge. Furthermore, the two clinical modalities used to deliver SRS, LINAC and GK, demonstrated differential effects on the tumor landscape even between controlled primary sites. Our study provides, in human, biological evidence of differential effects of SRS across BM's.

Antibacterial Activities of Methanolic Seeds Extract of Black pepper (Piper nigrum L.) against Gram Positive Staphylococcus aureus & Gram-Negative Escherichia coli

Evaluation of the in vitro antibacterial activity of Methanolic extracts isolated from Black pepper seeds (Piper nigrum L.) against two infection causing pathogens, Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Between July 2022 and June 2023, this experimental study was conducted at the Mymensingh Medical College's Department of Pharmacology and Therapeutics in conjunction with the Department of Microbiology. Using the disc diffusion and broth dilution methods, the antibacterial activity of methanolic extract of black pepper seeds (MBPE) was evaluated at various doses. The solvents Methanol and 10.0% Di Methyl Sulfoxide (DMSO) were used to make the extract. Using the broth dilution procedure, the conventional antibiotic Ciprofloxacin was utilized and the outcome was contrasted with that of Methanol extracts. Methanolic extract of black pepper seeds (MBPE) at seven distinct concentrations (100, 80, 60, 40, 20, 10 and 5 mg/ml) were utilized, then later in chosen concentrations as needed to confirm the extracts' more precise margin of antimicrobial sensitivity. At 80 mg/ml and above doses of the MBPE, it had an inhibitory impact against the aforementioned microorganisms. For Staphylococcus aureus and Escherichia coli the MIC were 60 and 75 mg/ml in MBPE respectively. As of the MIC of Ciprofloxacin was 1μg/ml against Staphylococcus aureus and Escherichia coli. In comparison to MICs of MBPE for the test organisms, the MIC of Ciprofloxacin was the lowest. This study clearly shows that Staphylococcus aureus and Escherichia coli are sensitive to the methanolic extract of black pepper seeds' antibacterial properties.

ARF4-mediated retrograde trafficking as a driver of chemoresistance in GBM

BACKGROUND

Cellular functions hinge on the meticulous orchestration of protein transport, both spatially and temporally. Central to this process is retrograde trafficking, responsible for targeting proteins to the nucleus. Despite its link to many diseases, the implications of retrograde trafficking in glioblastoma (GBM) are still unclear.

METHODS

To identify genetic drivers of TMZ resistance, we conducted comprehensive CRISPR-knockout screening, revealing ADP-ribosylation factor 4 (ARF4), a regulator of retrograde trafficking, as a major contributor.

RESULTS

Suppressing ARF4 significantly enhanced TMZ sensitivity in GBM patient-derived xenograft (PDX) models, leading to improved survival rates (p<0.01) in both primary and recurrent lines. We also observed that TMZ exposure stimulates ARF4-mediated retrograde trafficking. Proteomics analysis of GBM cells with varying levels of ARF4 unveiled the influence of this pathway on EGFR signaling, with increased nuclear trafficking of EGFR observed in cells with ARF4 overexpression and TMZ treatment. Additionally, spatially-resolved RNA-sequencing of GBM patient tissues revealed substantial correlations between ARF4 and crucial nuclear EGFR (nEGFR) downstream targets, such as MYC, STAT1, and DNA-PK. Decreased activity of DNA-PK, a DNA repair protein downstream of nEGFR signaling that contributes to TMZ resistance, was observed in cells with suppressed ARF4 levels. Notably, treatment with DNA-PK inhibitor, KU57788, in mice with a recurrent PDX line resulted in prolonged survival (p<0.01), highlighting the promising therapeutic implications of targeting proteins reliant on ARF4-mediated retrograde trafficking.

CONCLUSION

Our findings demonstrate that ARF4-mediated retrograde trafficking contributes to the development of TMZ resistance, cementing this pathway as a viable strategy to overcome chemoresistance in GBM.

Myeloid cell-derived creatine in the hypoxic niche promotes glioblastoma growth

Glioblastoma (GBM) is a malignancy dominated by the infiltration of tumor-associated myeloid cells (TAMCs). Examination of TAMC metabolic phenotypes in mouse models and patients with GBM identified the de novo creatine metabolic pathway as a hallmark of TAMCs. Multi-omics analyses revealed that TAMCs surround the hypoxic peri-necrotic regions of GBM and express the creatine metabolic enzyme glycine amidinotransferase (GATM). Conversely, GBM cells located within these same regions are uniquely specific in expressing the creatine transporter (SLC6A8). We hypothesized that TAMCs provide creatine to tumors, promoting GBM progression. Isotopic tracing demonstrated that TAMC-secreted creatine is taken up by tumor cells. Creatine supplementation protected tumors from hypoxia-induced stress, which was abrogated with genetic ablation or pharmacologic inhibition of SLC6A8. Lastly, inhibition of creatine transport using the clinically relevant compound, RGX-202-01, blunted tumor growth and enhanced radiation therapy in vivo. This work highlights that myeloid-to-tumor transfer of creatine promotes tumor growth in the hypoxic niche.

Current Trends of Using Antimicrobials in Acute Watery Diarrhoea in Children Below 5 Years of Age at Paediatrics Outpatient Department of a Tertiary Care Hospital in Bangladesh

Childhood diarrhoea is a major public health problem in developing countries like Bangladesh which is commonly caused by intestinal infection, mainly viral. Diarrhoea is causing second leading mortality in children below 5 years, where about 2 billion cases occur globally in each year. This study was proposed to evaluate the antimicrobials utilization pattern prescribed for AWD in children below 5 years of age, in a tertiary care hospital in Bangladesh. This record based, cross-sectional, descriptive type of observational study carried out at pharmacology department of Mymensingh Medical College. A total of 205 diarrhoeal patient's up to 5 years of age, attending the paediatric OPD from January 2021 to December 2021, were enrolled in the study. Out of 205 patients 182(88.8%) were prescribed antimicrobials. Azithromycin was the most frequently prescribed antimicrobial (60.0%) and among the antiprotozoals metronidazole was the prescribed most (24.9%). ORS and Zinc were prescribed in all patients (100%). Empirical excessive use of antibiotics was observed in this study. Emphasis on educational and training programs may help in a better and judicious use of drugs in children.

Metixene is an incomplete autophagy inducer in preclinical models of metastatic cancer and brain metastases

A paucity of chemotherapeutic options for metastatic brain cancer limits patient survival and portends poor clinical outcomes. Using a CNS small-molecule inhibitor library of 320 agents known to be blood-brain barrier permeable and approved by the FDA, we interrogated breast cancer brain metastasis vulnerabilities to identify an effective agent. Metixene, an antiparkinsonian drug, was identified as a top therapeutic agent that was capable of decreasing cellular viability and inducing cell death across different metastatic breast cancer subtypes. This agent significantly reduced mammary tumor size in orthotopic xenograft assays and improved survival in an intracardiac model of multiorgan site metastases. Metixene further extended survival in mice bearing intracranial xenografts and in an intracarotid mouse model of multiple brain metastases. Functional analysis revealed that metixene induced incomplete autophagy through N-Myc downstream regulated 1 (NDRG1) phosphorylation, thereby leading to caspase-mediated apoptosis in both primary and brain-metastatic cells, regardless of cancer subtype or origin. CRISPR/Cas9 KO of NDRG1 led to autophagy completion and reversal of the metixene apoptotic effect. Metixene is a promising therapeutic agent against metastatic brain cancer, with minimal reported side effects in humans, which merits consideration for clinical translation.

Antibacterial Activities of Mint (Mentha piperita) Leaf Extracts (Aqueous) Against Two Food Borne infection causing pathogens: Staphylococcus aureus and Escherichia coli

Evaluation of the in vitro antibacterial activity of Aqueous extracts isolated from Mint (Mentha piperita) leaf against two food born infection causing pathogens, gram-positive Staphylococcus aureus and gram-negative Escherichia coli. This interventional study was carried out in the Department of Pharmacology and Therapeutics in collaboration with the Department of Microbiology, Mymensingh Medical College, Bangladesh from January 2021 to December 2021. The antibacterial activity was tested at different concentrations of Aqueous Mint leaf extracts by using disc diffusion & broth dilution method. The extract was prepared by using solvents Aqueous. The test microorganisms were also tested for their activity against a standard antibiotic Gentamicin by broth dilution method and the result was compared with that of Aqueous extracts. Aqueous extract of Mint leaves (AMLE) were used initially in eight different concentrations (25, 50, 100, 200, 400, 600, 800 and 1000μg/ml) and later in selected concentrations as needed to confirm the more precise margin of antimicrobial sensitivity of the extracts. Among different concentrations of the AMLE, 200μg/ml and above concentrations showed inhibitory effect against Staphylococcus aureus and 400μg/ml and above concentrations showed inhibitory effect against Escherichia coli. Minimum inhibitory concentration (MIC) for Staphylococcus aureus and Escherichia coli were 200 and 400μg/ml in AMLE respectively. The MIC of Gentamicin was 1μg/ml against Staphylococcus aureus and 1.5μg/ml against Escherichia coli. The MIC of Gentamicin was the lowest in comparison to MICs of AMLE for the test organisms. This study showed that Aqueous Mint extracts demonstrated antibacterial effects against food borne pathogens. It is clearly observed that there is definite antibacterial effect of the aqueous extract of Mint leaves against Staphylococcus aureus and Escherichia coli.

Pattern of Prescribing Drugs in Chronic Obstructive Pulmonary Disease in a Tertiary Care Hospital of Bangladesh

Chronic obstructive pulmonary disease (COPD) is a chronic obstructive disease of the airways. It is one of the most common and important chronic respiratory conditions in terms of years lived with disability. Incidence is increasing in Bangladesh like other developing countries. To evaluate drug prescription pattern for COPD, this cross-sectional, observational study was conducted from January to December in 2020 at the Department of Pharmacology in collaboration with the Department of Medicine in Mymensingh Medical College, Bangladesh. A total of 168 patients were selected for the study by non-random purposive sampling technique. Age distribution indicates that 31.5% of patients were in the 50-59 years age group and males were 93.5%. The majority (82.1%) of the participants were smokers. In this study, majority (34.12%) of the drugs were used as oral form and second most common dosage form was nebulization (26.75%). Bronchodilators were mostly prescribed 652(57.19%), followed by corticosteroids 222(19.47%) and antibiotics 165(14.47%) among drugs used for COPD. Beta sympathomimetics 322(45.49%) were mostly prescribed, followed by anticholinergics 186(28.52%) and methylxanthines 144(22.08%) as bronchodilators. Out of 1140 drugs for COPD, 53.06% and 34.12% were delivered as inhalation and oral forms, respectively. Inhalation route was the most (60.37%) preferred one over oral route (37.63%) for steroid use. The most of the patients [152 (90.48%)] were treated with combination therapy. Mostly (39.6%) used Fixed Dose Combination (FDC) therapy was salbutamol and ipratropium bromide followed by salmeteroal and Fluticasone (30.83%). Both FDC were prescribed in 57.7% of study population. Considering nomenclature, trade name was used in 24.4% of prescription.

Ribonucleotide reductase regulatory subunit M2 drives glioblastoma TMZ resistance through modulation of dNTP production

During therapy, adaptations driven by cellular plasticity are partly responsible for driving the inevitable recurrence of glioblastoma (GBM). To investigate plasticity-induced adaptation during standard-of-care chemotherapy temozolomide (TMZ), we performed in vivo single-cell RNA sequencing in patient-derived xenograft (PDX) tumors of GBM before, during, and after therapy. Comparing single-cell transcriptomic patterns identified distinct cellular populations present during TMZ therapy. Of interest was the increased expression of ribonucleotide reductase regulatory subunit M2 (RRM2), which we found to regulate dGTP and dCTP production vital for DNA damage response during TMZ therapy. Furthermore, multidimensional modeling of spatially resolved transcriptomic and metabolomic analysis in patients' tissues revealed strong correlations between RRM2 and dGTP. This supports our data that RRM2 regulates the demand for specific dNTPs during therapy. In addition, treatment with the RRM2 inhibitor 3-AP (Triapine) enhances the efficacy of TMZ therapy in PDX models. We present a previously unidentified understanding of chemoresistance through critical RRM2-mediated nucleotide production.

Endoplasmic Reticulum Stress in the Brain Tumor Immune Microenvironment

Immunotherapy has emerged as a powerful strategy for halting cancer progression. However, primary malignancies affecting the brain have been exempt to this success. Indeed, brain tumors continue to portend severe morbidity and remain a globally lethal disease. Extensive efforts have been directed at understanding how tumor cells survive and propagate within the unique microenvironment of the central nervous system (CNS). Cancer genetic aberrations and metabolic abnormalities provoke a state of persistent endoplasmic reticulum (ER) stress that in turn promotes tumor growth, invasion, therapeutic resistance, and the dynamic reprogramming of the infiltrating immune cells. Consequently, targeting ER stress is a potential therapeutic approach. In this work, we provide an overview of how ER stress response is advantageous to brain tumor development, discuss the significance of ER stress in governing antitumor immunity, and put forth therapeutic strategies of regulating ER stress to augment the effect of immunotherapy for primary CNS tumors.

Genomic Analysis of Human Brain Metastases Treated with Stereotactic Radiosurgery Under the Phase-II Clinical Trial (NCT03398694) Reveals DNA Damage Repair at the Peripheral Tumor Edge

Stereotactic Radiosurgery (SRS) is one of the leading treatment modalities for oligo brain metastasis (BM), however no comprehensive genomic data assessing the effect of radiation on BM in humans exist. Leveraging a unique opportunity, as part of the clinical trial (NCT03398694), we collected post-SRS, delivered via Gamma-knife or LINAC, tumor samples from core and peripheral-edges of the resected tumor to characterize the genomic effects of overall SRS as well as the SRS delivery modality. Using these rare patient samples, we show that SRS results in significant genomic changes at DNA and RNA levels throughout the tumor. Mutations and expression profiles of peripheral tumor samples indicated interaction with surrounding brain tissue as well as elevated DNA damage repair. Central samples show GSEA enrichment for cellular apoptosis while peripheral samples carried an increase in tumor suppressor mutations. There are significant differences in the transcriptomic profile at the periphery between Gamma-knife vs LINAC.

Checkpoint: Inspecting the barriers in glioblastoma immunotherapies

Despite an aggressive standard of care involving radiation therapy, temozolomide-based chemotherapy, and surgical resection, glioblastoma multiforme (GBM) continues to exhibit very high recurrence and mortality rates partly due to the highly plastic and heterogenous nature of the tumor. In recent years, activation of the immune system has emerged as a promising strategy in cancer therapies. However, despite recent successes in other fields, immunotherapeutic approaches continue to encounter challenges in GBM. In this review, we first discuss immunotherapies targeting the most well-studied immune checkpoint proteins, CTLA-4 and PD-1, followed by discussions on therapies targeting immune-stimulatory molecules and secreted metabolic enzymes. Finally, we address the major challenges with immunotherapy in GBM and the potential for combination and neoadjuvant immunotherapies to tip the scales in the fight against glioblastoma.

Abstract PR011: Targeting cellular plasticity-driven metabolic adaptation to overcome chemoresistance in GBM

Glioblastoma is an incredibly aggressive primary brain tumor that is universally lethal due to 100% recurrence. Recent research has pointed to the existence of a population of cells that possess stem cell-like characteristics that are resistant to conventional therapy and can initiate recurrence. Our laboratory, along with others, has demonstrated that this stem-like state is plastic and can be acquired by otherwise differentiated GBM cells exposed to different stress, including stress generated by chemotherapy. Our Initial investigation indicated that Polycomb group protein EZH2 is critical for therapeutic stress-induced cellular plasticity. Further investigation revealed that the mechanisms of EZH2-mediated cellular plasticity are partly governed by a novel downstream target ARL13B, a member of the ADP-ribosylation factor-like family protein critical for cilia formation and maintenance. ARl13B removal significantly reduced different stemness factors such as nestin, SOX2, and most importantly, sensitized different subtypes of patient-derived xenograft lines to temozolomide-based chemotherapy both in vitro and in vivo (p&lt;.0001). Mass spectroscopy analysis revealed that ARL13B could directly interact with inosine monophosphate dehydrogenase 2 (IMPDH2), the rate-limiting enzyme purine biosynthesis. We further show that interaction between ARL13B and IMPDH2 is necessary for utilization of the de novo pathway during chemotherapy temozolomide (TMZ) treatment in that loss of ARL13B enhanced salvage (p-value&lt;0.0001) and reduced de novo activity (p-value&lt;0.0001). Loss of ARL13B causes a significant increase in DNA double-strand breaks in a TMZ-dependent manner as measured by γH2AX foci staining (p-value&lt;0.0001). Based on these data, we propose that blocking the switch from salvage to de novo synthesis will force the tumor cells to recycle the damaged purines, thus effectively sensitizing them to TMZ therapy. By using an FDA-approved inhibitor of IMPDH2, mycophenolate mofetil (MMF), we have demonstrated that concurrent treatment with TMZ and MMF confers a significant survival benefit in the patient-derived orthotopic xenograft mouse models (p-value=0.004). Therefore, we proposed that the cellular plasticity driven ARL13B-IMPDH2 regulated switch from the salvage pathway to the de novo purine biosynthesis pathway is necessary for GBM cells’ adaptation to alkylating-based chemotherapy, and we are now starting a clinical trial to test this hypothesis.

Citation Format: Atique U. Ahmed, Jack M. Shireman, Fatemeh Atash, Gina Lee, Eunus S. Ali, Miranda R. Saathoff, Cheol H. Park, Sol Savchuk, Shivani Baisiwala, Jason Miska, Maciej S. Lesniak, C. David James, Roger Stupp, Priya Kumthekar, Craig M. Horbinski, Issam Ben-Sahra. Targeting cellular plasticity-driven metabolic adaptation to overcome chemoresistance in GBM [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr PR011.

Abstract B034: Targeting cellular plasticity-driven metabolic adaptation to overcome chemoresistance in GBM

This abstract is being presented as a short talk in the scientific program. A full abstract is available in the Proffered Abstracts section (PR011) of the Conference Proceedings.

Citation Format: Atique U. Ahmed, Jack M. Shireman, Fatemeh Atash, Gina Lee, Eunus S. Ali, Miranda R. Saathoff, Cheol H. Park, Sol Savchuk, Shivani Baisiwala, Jason Miska, Maciej S. Lesniak, C. David James, Roger Stupp, Priya Kumthekar, Craig M. Horbinski, Issam Ben-Sahra. Targeting cellular plasticity-driven metabolic adaptation to overcome chemoresistance in GBM [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr B034.

Translocon-associated protein subunit SSR3 determines and predicts susceptibility to paclitaxel in breast cancer and glioblastoma

PURPOSE

Paclitaxel (PTX) is one the most potent and commonly used chemotherapies for breast and pancreatic cancer. Several ongoing clinical trials are investigating means of enhancing delivery of PTX across the blood-brain barrier for glioblastomas (GBMs). Despite the widespread use of PTX for breast cancer, and the initiative to repurpose this drug for gliomas, there are no predictive biomarkers to inform which patients will likely benefit from this therapy.

EXPERIMENTAL DESIGN

To identify predictive biomarkers for susceptibility to PTX, we performed a genome-wide CRISPR knock-out (KO) screen using human glioma cells. The genes whose KO was most enriched in the CRISPR screen underwent further selection based on their correlation with survival in the breast cancer patient cohorts treated with PTX and not in patients treated with other chemotherapies, a finding that was validated on a second independent patient cohort using progression-free survival.

RESULTS

Combination of CRISPR screen results with outcomes from taxane-treated breast cancer patients led to the discovery of endoplasmic reticulum (ER) protein SSR3 as a putative predictive biomarker for PTX. SSR3 protein levels showed positive correlation with susceptibility to PTX in breast cancer cells, glioma cells and in multiple intracranial glioma xenografts models. Knockout of SSR3 turned the cells resistant to PTX while its overexpression sensitized the cells to PTX. Mechanistically, SSR3 confers susceptibility to PTX through regulation of phosphorylation of ER stress sensor IRE1α.

CONCLUSION

Our hypothesis generating study showed SSR3 as a putative biomarker for susceptibility to PTX, warranting its prospective clinical validation.

Circadian Regulator CLOCK Drives Immunosuppression in Glioblastoma

The symbiotic interactions between cancer stem cells and the tumor microenvironment (TME) are critical for tumor progression. However, the molecular mechanism underlying this symbiosis in glioblastoma (GBM) remains enigmatic. Here, we show that circadian locomotor output cycles kaput (CLOCK) and its heterodimeric partner brain and muscle ARNT-like 1 (BMAL1) in glioma stem cells (GSCs) drive immunosuppression in GBM. Integrated analyses of the data from transcriptome profiling, single-cell RNA sequencing, and TCGA datasets, coupled with functional studies, identified legumain (LGMN) as a direct transcriptional target of the CLOCK-BMAL1 complex in GSCs. Moreover, CLOCK-directed olfactomedin-like 3 (OLFML3) upregulates LGMN in GSCs via hypoxia-inducible factor 1-alpha (HIF1α) signaling. Consequently, LGMN promotes microglial infiltration into the GBM TME via upregulating CD162 and polarizes infiltrating microglia towards an immune-suppressive phenotype. In GBM mouse models, inhibition of the CLOCK-OLFML3-HIF1α-LGMN-CD162 axis reduces intratumoral immune-suppressive microglia, increases CD8+ T-cell infiltration, activation and cytotoxicity, and synergizes with anti-PD1 therapy. In human GBM, the CLOCK-regulated LGMN signaling correlates positively with microglial abundance and poor prognosis. Together, these findings uncover the CLOCK-OLFML3-HIF1α-LGMN axis as a molecular switch that controls microglial biology and immunosuppression, thus revealing potential new therapeutic targets for GBM patients.

Neural stem cell delivery of an oncolytic adenovirus in newly diagnosed malignant glioma: a first-in-human, phase 1, dose-escalation trial

BACKGROUND

Malignant glioma is the most common and lethal primary brain tumour, with dismal survival rates and no effective treatment. We examined the safety and activity of NSC-CRAd-S-pk7, an engineered oncolytic adenovirus delivered by neural stem cells (NSCs), in patients with newly diagnosed high-grade glioma.

METHODS

This was a first-in-human, open-label, phase 1, dose-escalation trial done to determine the maximal tolerated dose of NSC-CRAd-S-pk7, following a 3 + 3 design. Patients with newly diagnosed, histologically confirmed, high-grade gliomas (WHO grade III or IV) were recruited. After neurosurgical resection, NSC-CRAd-S-pk7 was injected into the walls of the resection cavity. The first patient cohort received a dose starting at 6·25 × 10¹⁰ viral particles administered by 5·00 × 10⁷ NSCs, the second cohort a dose of 1·25 × 10¹¹ viral particles administered by 1·00 × 10⁸ NSCs, and the third cohort a dose of 1·875 × 10¹¹ viral particles administered by 1·50 × 10⁸ NSCs. No further dose escalation was planned. Within 10-14 days, treatment with temozolomide and radiotherapy was initiated. Primary endpoints were safety and toxicity profile and the maximum tolerated dose for a future phase 2 trial. All analyses were done in all patients who were included in the trial and received the study treatment and were not excluded from the study. Recruitment is complete and the trial is finished. The trial is registered with ClinicalTrials.gov, NCT03072134.

FINDINGS

Between April 24, 2017, and Nov 13, 2019, 12 patients with newly diagnosed, malignant gliomas were recruited and included in the safety analysis. Histopathological evaluation identified 11 (92%) of 12 patients with glioblastoma and one (8%) of 12 patients with anaplastic astrocytoma. The median follow-up was 18 months (IQR 14-22). One patient receiving 1·50 × 10⁸ NSCs loading 1·875 × 10¹¹ viral particles developed viral meningitis (grade 3) due to the inadvertent injection of NSC-CRAd-S-pk7 into the lateral ventricle. Otherwise, treatment was safe as no formal dose-limiting toxicity was reached, so 1·50 × 10⁸ NSCs loading 1·875 × 10¹¹ viral particles was recommended as a phase 2 trial dose. There were no treatment-related deaths. The median progression-free survival was 9·1 months (95% CI 8·5-not reached) and median overall survival was 18·4 months (15·7-not reached).

INTERPRETATION

NSC-CRAd-S-pk7 treatment was feasible and safe. Our immunological and histopathological findings support continued investigation of NSC-CRAd-S-pk7 in a phase 2/3 clinical trial.

FUNDING

US National Institutes of Health.

BET inhibition increases βIII-tubulin expression and sensitizes metastatic breast cancer in the brain to vinorelbine

Metastases from primary breast cancer result in poor survival. βIII-tubulin (TUBB3) has been established as a therapeutic target for breast cancer metastases specifically to the brain. In this study, we conducted a systematic analysis to determine the regulation of TUBB3 expression in breast cancer metastases to the brain and strategically target these metastases using vinorelbine (VRB), a drug approved by the U.S. Food and Drug Administration (FDA). We found that human epidermal growth factor receptor 2 (HER2) signaling regulates TUBB3 expression in both trastuzumab-sensitive and trastuzumab-resistant neoplastic cells. We further discovered that bromodomain and extra-terminal domain (BET) inhibition increases TUBB3 expression, rendering neoplastic cells more susceptible to apoptosis by VRB. Orthotopic xenograft assays using two different breast cancer cell models revealed a reduction in tumor volume with BET inhibition and VRB treatment. In addition, in vivo studies using a model of multiple brain metastasis (BM) showed improved survival with the combination of radiation + BET inhibitor (iBET-762) + VRB (75% long-term survivors, P < 0.05). Using in silico analysis and BET inhibition, we found that the transcription factor myeloid zinc finger-1 (MZF-1) protein binds to the TUBB3 promoter. BET inhibition decreases MZF-1 expression and subsequently increases TUBB3 expression. Overexpression of MZF-1 decreases TUBB3 expression and reduces BM in vivo, whereas its knockdown increases TUBB3 expression in breast cancer cells. In summary, this study demonstrates a regulatory mechanism of TUBB3 and provides support for an application of BET inhibition to sensitize breast cancer metastases to VRB-mediated therapy.

Molecular Classification of Gliomas is Associated with Seizure Control: A Retrospective Analysis

Classically, histologic grading of gliomas has been used to predict seizure association, with low-grade gliomas associated with an increased incidence of seizures compared to high-grade gliomas. In 2016, WHO reclassified gliomas based on histology and molecular characteristics. We sought to determine whether molecular classification of gliomas is associated with preoperative seizure presentation and/or post-operative seizure control across multiple glioma subtypes. All gliomas operated at our institution from 2007 to 2017 were identified based on ICD 9 and 10 billing codes and were retrospectively assessed for molecular classification of the IDH1 mutation, and 1p/19q codeletion. Logistic regression models were performed to assess associations of seizures at presentation as well as post-operative seizures with IDH status and the new WHO integrated classification. Our study included 376 patients: 82 IDH mutant and 294 IDH wildtype. The presence of IDH mutation was associated with seizures at presentation [OR 3.135 (1.818-5.404), p < 0.001]. IDH-mutant glioblastomas presented with seizures less often than other IDH-mutant glioma subtypes grade II and III [OR 0.104 (0.032-0.340), p < 0.001]. IDH-mutant tumors were associated with worse post-operative seizure outcomes, demonstrated by Engel Class [OR 2.666 (1.592-4.464), p < 0.001]. IDH mutation in gliomas is associated with an increased risk of seizure development and worse post-operative seizure control, in all grades except for GBM.

De novo purine biosynthesis is a major driver of chemoresistance in glioblastoma

Glioblastoma is a primary brain cancer with a near 100% recurrence rate. Upon recurrence, the tumour is resistant to all conventional therapies, and because of this, 5-year survival is dismal. One of the major drivers of this high recurrence rate is the ability of glioblastoma cells to adapt to complex changes within the tumour microenvironment. To elucidate this adaptation's molecular mechanisms, specifically during temozolomide chemotherapy, we used chromatin immunoprecipitation followed by sequencing and gene expression analysis. We identified a molecular circuit in which the expression of ciliary protein ADP-ribosylation factor-like protein 13B (ARL13B) is epigenetically regulated to promote adaptation to chemotherapy. Immuno-precipitation combined with liquid chromatography-mass spectrometry binding partner analysis revealed that that ARL13B interacts with the purine biosynthetic enzyme inosine-5'-monophosphate dehydrogenase 2 (IMPDH2). Further, radioisotope tracing revealed that this interaction functions as a negative regulator for purine salvaging. Inhibition of the ARL13B-IMPDH2 interaction enhances temozolomide-induced DNA damage by forcing glioblastoma cells to rely on the purine salvage pathway. Targeting the ARLI3B-IMPDH2 circuit can be achieved using the Food and Drug Administration-approved drug, mycophenolate mofetil, which can block IMPDH2 activity and enhance the therapeutic efficacy of temozolomide. Our results suggest and support clinical evaluation of MMF in combination with temozolomide treatment in glioma patients.

Abstract 197: Identifying a novel network of driver genes in glioblastoma

The purpose of this study is to identify novel genes that drive proliferation in glioblastoma (GBM) and likely contribute to gliomagenesis, therefore facilitating the aggressive nature of the tumor.

GBM is an aggressive primary malignancy of the brain with almost a 100% recurrence rate. It is the most common malignant brain tumor in adults, with an average survival of 21 months after diagnosis, with the current standard of care. As such, new advances in therapy are desperately needed. Large scale genomic approaches have shown that GBM has a complex genetic architecture, with a great deal of intratumoral heterogeneity. However, a more comprehensive understanding of determinants of growth is required to identify new targets and provide new therapeutic strategies.

CRISPR-Cas9 screening technology has enabled whole-genome screens that allow for systematic and objective identification of genes governing cell viability and proliferation. These genes may represent unique vulnerabilities that can be targeted with novel therapeutics. Here, we performed a genome-wide CRISPR knockout screen in SNB19 human GBM cells, covering 17,000 genes with 4 guides per gene. In this type of screen, we anticipate that those guides that are depleted over time are the ones that correspond to genes driving growth and proliferation of GBM cells. Initial analysis showed that there was a reduction in guides for known driver genes, as we might expect. However, in addition to known drivers, we were able to identify a list of approximately 150 new genes that showed significant depletion in our screen (p&lt;0.01), meaning that they likely contribute to the viability of GBM cells. From this list, we identified 5 previously unstudied genes, which show significant elevations in expression at the RNA and protein levels (p&lt;0.05), and show significant survival benefit in patient datasets (p&lt;0.05). For these genes, we first validated expression in multiple patient-derived xenograft (PDX) lines. We were able to confirm that compared to a neural stem cell (NSC) control, all genes showed a significant elevation in protein expression in the PDX lines. Furthermore, we were able to generate CRISPR-Cas9 knockouts in our NSC line and in each of our PDX lines. These knockouts showed a significant reduction in viability in PDX lines (p&lt;0.01) while showing no significant effect on viability in the NSC line. In addition, intracranial implantation of the knockout PDX cells in mice shows an increase in survival compared to control. In addition to identifying genes that may represent therapeutic vulnerabilities, we have further been able to identify pathways that may be potential targets. Specifically, proteasomal degradation, mRNA transport, and ribosomal processes show significant enrichment in our set of genes (FDR &lt; .25).

In summary, we have used a whole-genome CRISPR-Cas9 knockout screen to identify a large novel set of genes that contributes to glioma viability and proliferation. Of these genes, we have been able to further validate a limited set to show that they do in fact contribute to the survival of cells in vitro and animal survival in vivo. Finally, we have been able to show enrichment of specific pathways across these gene sets, giving us a set of genes and pathways that represent novel genetic vulnerabilities. We believe this work will contribute significantly to developing new therapies for a disease that is desperately in need of additional therapeutic options.

Citation Format: Shivani Baisiwala, Cheol Park, Chidibere Awah, Jack M. Shireman, Miranda R. Saathoff, Adam Sonabend, Atique U. Ahmed. Identifying a novel network of driver genes in glioblastoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 197.

Glioblastoma Recurrence and the Role of O6-Methylguanine-DNA Methyltransferase Promoter Methylation

Tumor recurrence in glioblastoma multiforme (GBM) is often attributed to acquired resistance to the standard chemotherapeutic agent, temozolomide (TMZ). Promoter methylation of the DNA repair gene MGMT (O⁶-methylguanine-DNA methyltransferase) has been associated with sensitivity to TMZ, whereas increased expression of MGMT has been associated with TMZ resistance. Clinical studies have observed a downward shift in MGMT methylation percentage from primary to recurrent stage tumors; however, the evolutionary processes that drive this shift and more generally the emergence and growth of TMZ-resistant tumor subpopulations are still poorly understood. Here, we develop a mathematical model, parameterized using clinical and experimental data, to investigate the role of MGMT methylation in TMZ resistance during the standard treatment regimen for GBM-surgery, chemotherapy, and radiation. We first found that the observed downward shift in MGMT promoter methylation status between detection and recurrence cannot be explained solely by evolutionary selection. Next, our model suggests that TMZ has an inhibitory effect on maintenance methylation of MGMT after cell division. Finally, incorporating this inhibitory effect, we study the optimal number of TMZ doses per adjuvant cycle for patients with GBM with high and low levels of MGMT methylation at diagnosis.

HIF-1α Is a Metabolic Switch between Glycolytic-Driven Migration and Oxidative Phosphorylation-Driven Immunosuppression of Tregs in Glioblastoma

The mechanisms by which regulatory T cells (Tregs) migrate to and function within the hypoxic tumor microenvironment are unclear. Our studies indicate that specific ablation of hypoxia-inducible factor 1α (HIF-1α) in Tregs results in enhanced CD8⁺ T cell suppression versus wild-type Tregs under hypoxia, due to increased pyruvate import into the mitochondria. Importantly, HIF-1α-deficient Tregs are minimally affected by the inhibition of lipid oxidation, a fuel that is critical for Treg metabolism in tumors. Under hypoxia, HIF-1α directs glucose away from mitochondria, leaving Tregs dependent on fatty acids for mitochondrial metabolism within the hypoxic tumor. Indeed, inhibition of lipid oxidation enhances the survival of mice with glioma. Interestingly, HIF-1α-deficient-Treg mice exhibit significantly enhanced animal survival in a murine model of glioma, due to their stymied migratory capacity, explaining their reduced abundance in tumor-bearing mice. Thus HIF-1α acts as a metabolic switch for Tregs between glycolytic-driven migration and oxidative phosphorylation-driven immunosuppression.

Miska et al. demonstrate that regulatory T cell (Treg)-specific depletion of HIF-1α promotes enhanced immune suppression at the cost of migration under hypoxic conditions. Within the hypoxic brain-tumor environment, Tregs are uniquely able to metabolize extracellular free fatty acids to promote their immunosuppressive functionality, which can be targeted in vivo.

Monoamines in glioblastoma: complex biology with therapeutic potential

Glioblastoma (GBM) is characterized by extremely poor prognoses, despite the use of gross surgical resection, alkylating chemotherapeutic agents, and radiotherapy. Evidence increasingly highlights the role of the tumor microenvironment in enabling this aggressive phenotype. Despite this interest, the role of neurotransmitters, brain-specific messengers underlying synaptic transmission, remains murky. These signaling molecules influence a complex network of molecular pathways and cellular behaviors in many CNS-resident cells, including neural stem cells and progenitor cells, neurons, and glia cells. Critically, available data convincingly demonstrate that neurotransmitters can influence proliferation, quiescence, and differentiation status of these cells. This ability to affect progenitors and glia-GBM-initiating cells-and their availability in the CNS strongly support the notion that neurotransmitters participate in the onset and progression of GBM. This review will focus on dopamine and serotonin, as studies indicate they contribute to gliomagenesis. Particular attention will be paid to how these neurotransmitters and their receptors can be utilized as novel therapeutic targets. Overall, this review will analyze the complex biology governing the interaction of GBM with neurotransmitter signaling and highlight how this interplay shapes the aggressive nature of GBM.

FABP7 is a key metabolic regulator in HER2+ breast cancer brain metastasis

Overexpression of human epidermal growth factor receptor 2 (HER2) in breast cancer patients is associated with increased incidence of breast cancer brain metastases (BCBM), but the mechanisms underlying this phenomenon remain unclear. Here, to identify brain-predominant genes critical for the establishment of BCBM, we conducted an in silico screening analysis and identified that increased levels of fatty acid-binding protein 7 (FABP7) correlate with a lower survival and higher incidence of brain metastases in breast cancer patients. We validated these findings using HER2+ BCBM cells compared with parental breast cancer cells. Importantly, through knockdown and overexpression assays, we characterized the role of FABP7 in the BCBM process in vitro and in vivo. Our results uncover a key role of FABP7 in metabolic reprogramming of HER2 + breast cancer cells, supporting a glycolytic phenotype and storage of lipid droplets that enable their adaptation and survival in the brain microenvironment. In addition, FABP7 is shown to be required for upregulation of key metastatic genes and pathways, such as integrins-Src and VEGFA, and for the growth of HER2+ breast cancer cells in the brain microenvironment in vivo. Together, our results support FABP7 as a potential target for the treatment of HER2+ BCBM.

Abstract 81: ARL13B interacts with IMPDH2 to modulate purine synthesis and temozolomide resistance in glioblastoma

Glioblastoma, a universally lethal primary brain tumor, harnesses cellular plasticity to drive therapeutic adaptation. Critical factors in developing this plasticity are histone modifiers such as Polycomb Repressor Complex 2 protein EZH2. In order to examine tumor cell plasticity in depth, we conducted multiple ChIP Sequencing runs and demonstrate that EZH2 binds within an enhancer region of ARL13B during temozolomide (TMZ) therapy and induces an H3K4 mono-methylation mark. Concurrently, we observed an increase in H3K27ac at the transcription start site of ARL13B as well as a lack of H3K27 tri-methylation, EZH2’s canonical histone mark. Based on this we hypothesize that EZH2 could be non-canonically regulating ARL13B to allow for cellular plasticity and ultimately drive therapeutic adaptation. Delving further into this regulation we demonstrate that knockdown of ARL13B in patient derived xenograft cells significantly increased survival of mice in an orthotopic GBM model when compared to controls (p-value &lt;0.0001). The Cancer Genome Atlas (TCGA) patient dataset demonstrates time to recurrence in patients with downregulated ARL13B is substantially increased as compared to ARL13B upregulated patients (log-rank p-value=0.0012). Searching for a mechanism behind this survival benefit, we preformed mass spectrometry on an ARL13B pulldown in a patient derived xenograft line during TMZ therapy and identified inosine monophosphate dehydrogenase 2 (IMPDH2), the rate-limiting enzyme in de-novo guanine nucleotide biosynthesis, as a significant binding partner of ARL13B during TMZ chemotherapy (p-value &lt;0.0001). Probing this novel interaction further we examined the de-novo and salvage purine biosynthesis pathways using radiolabeled carbon tracing experiments. In ARL13B knockdown cells, purine salvage pathway usage is upregulated 7-fold (p-value &lt;0.0001) while de-novo pathway usage was decreased about 50% (p-value=0.004) in a TMZ specific manner. Examination of IMPDH2 enzymatic activity using a formazin reduction assay demonstrated a decrease in activity over 8 days of TMZ exposure (p&lt;.001). Moreover, ARL13B knockdown GBM cells treated with TMZ show a robust increase in DNA double-strand breaks compared to control cells exposed to TMZ, demonstrated by γH2X staining. Finally, a potent inhibitor of IMPDH2 (Mycophenolate Mofetil) significantly extended median survival in an orthotopic PDX mouse model only when in combination with TMZ (p&lt;.01). Based on these data we hypothesize that EZH2 regulates a novel ARL13B and IMPDH2 interaction which when lost forces cells into salvage synthesis exclusively. This synthesis shift forces cells to uptake and incorporate purines that have been alkylated by TMZ therapy which increases DNA double strand breaks and ultimately impairs therapeutic adaptation.

Citation Format: Jack Shireman, Eunus Ali, Miranda Saathoff, Cheol Park, Issam Ben-Sahra, Atique U. Ahmed. ARL13B interacts with IMPDH2 to modulate purine synthesis and temozolomide resistance in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 81.

Diagnostic Clinical Trials in Breast Cancer Brain Metastases: Barriers and Innovations

Optimal treatment of breast cancer brain metastases (BCBM) is often hampered by limitations in diagnostic abilities. Developing innovative tools for BCBM diagnosis is vital for early detection and effective treatment. In this study we explored the advances in trial for the diagnosis of BCBM, with review of the literature. On May 8, 2019, we searched ClinicalTrials.gov for interventional and diagnostic clinical trials involving BCBM, without limiting for date or location. Information on trial characteristics, experimental interventions, results, and publications were collected and analyzed. In addition, a systematic review of the literature was conducted to explore published studies related to BCBM diagnosis. Only 9 diagnostic trials explored BCBM. Of these, 1 trial was withdrawn because of low accrual numbers. Three trials were completed; however, none had published results. Modalities in trial for BCBM diagnosis entailed magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), PET-CT, nanobodies, and circulating tumor cells (CTCs), along with a collection of novel tracers and imaging biomarkers. MRI continues to be the diagnostic modality of choice, whereas CT is best suited for acute settings. Advances in PET and PET-CT allow the collection of metabolic and functional information related to BCBM. CTC characterization can help reflect on the molecular foundations of BCBM, whereas cell-free DNA offers new genetic material for further exploration in trials. The integration of machine learning in BCBM diagnosis seems inevitable as we continue to aim for rapid and accurate detection and better patient outcomes.

Current state of clinical trials in breast cancer brain metastases

Background

Breast cancer brain metastases (BCBM) are the final frontier in neuro-oncology for which more efficacious therapies are required. In this work, we explore clinical trials in BCBM, and determine the shortcomings in the development of new BCBM therapies to shed light on potential areas for enhancement.

Methods

On July 9, 2018, we searched ClinicalTrials.gov for all interventional and therapeutic clinical trials involving BCBM, without limiting for date or location. Information on trial characteristics, including phase, status, start and end dates, study design, primary endpoints, selection criteria, sample size, experimental interventions, results, and publications were collected and analyzed.

Results

Fifty-three trials fulfilled the selection criteria. Median trial duration across phases ranged between 3 and 6 years. More than half of the trials were conducted in the United States. Although 94% of the trials were in early phases (I-II), 20% of patients were in phase III trials. Two phase III trials were anteceded by phase II trials that were non-randomized; one reported positive results. Approximately one-third of the trials were completed, whereas 23% of trials were terminated early; mostly due to inadequate enrollment. Only 13% of all trials and 22% of completed trials had published results directly linked to their primary outcomes.

Conclusions

The low number of trials and accrual numbers, the lack of diversity, and the scarcity of published results represent the main troubles in clinical BCBM research. Optimization of BCBM trials is necessary to achieve effective therapies.

A Dendritic Cell-Targeted Adenoviral Vector Facilitates Adaptive Immune Response Against Human Glioma Antigen (CMV-IE) and Prolongs Survival in a Human Glioma Tumor Model

Antitumor immunotherapeutic strategies represent an especially promising set of approaches with rapid translational potential considering the dismal clinical context of high-grade gliomas. Dendritic cells (DCs) are the body's most professional antigen-presenting cells, able to recruit and activate T cells to stimulate an adaptive immune response. In this regard, specific loading of tumor-specific antigen onto dendritic cells potentially represents one of the most advanced strategies to achieve effective antitumor immunization. In this study, we developed a DC-specific adenoviral (Ad) vector, named Ad5scFvDEC205FF, targeting the DC surface receptor, DEC205. In vitro analysis shows that 60% of DCs was infected by this vector while the infectivity of other control adenoviral vectors was less than 10%, demonstrating superior infectivity on DCs. Moreover, an average of 14% of DCs were infected by Ad5scFvDEC205FF-GFP, while less than 3% of non-DCs were infected following in vivo administration, demonstrating highly selective in vivo DC infection. Importantly, vaccination with this vehicle expressing human glioma-specific antigen, Ad5scFvDEC205FF-CMV-IE, shows a prolonged survival benefit in GL261CMV-IE-implanted murine glioma models (p < 0.0007). Furthermore, when rechallenged, cancerous cells were completely rejected. In conclusion, our novel, viral-mediated, DC-based immunization approach has the significant therapeutic potential for patients with high-grade gliomas.

Abstract 4949: The role of symmetric cell division in post-therapy glioma-initiating cell expansion

The purpose of this study is to elucidate the mechanism by which LNX1 regulates Notch1 to increase symmetric self-renewal of glioma-initiating cells (GICs) and thereby to expand the GIC population in glioblastoma (GBM) during therapy. GBM is an aggressive primary malignancy of the brain with an almost 100% recurrence rate. Our lab and others have shown that GBM contains a subpopulation of GICs that may drive the therapeutic resistance capabilities of recurrent GBM. We have shown that the GIC population expands following administration of temozolomide (TMZ), the most commonly used drug for antiglioma chemotherapy. While it has been suggested that this expansion relies solely on Darwinian selection, we and others have demonstrated that cellular plasticity-driven expansion of therapeutically resistant GICs post-therapy may play a role in disease recurrence. GICs follow the normal stem cell pattern of cell division. They can divide in three ways: (1) asymmetric division to form one GIC and one differentiated cancer cell, (2) symmetric self-renewal to form two daughter GICs, or (3) symmetric differentiation to form two cancer cells. Here, we used ImageStream flow cytometry analysis to show that symmetric self-renewal, where one GIC produces two daughter GICs, occurs at a rate of 24% in GBM cells treated with vehicle as compared to 54% following TMZ therapy (p&lt;0.0001). Gene set expression analysis (GSEA) on GBM patient-derived xenograft (PDX) cells after treatment with vehicle or TMZ showed a statistically significant enrichment of 29 genes involved in polarized cell division after TMZ (FDRq&lt;0.25). LNX1, a Notch1 regulator known to regulate symmetric cell division, was found to be enriched 8.7-fold in multiple GBM PDX lines (p&lt;0.0001). Furthermore, Western blotting of multiple GBM PDX cell lines showed that Notch1 antagonist Numb is significantly downregulated and that Notch1 and Notch1 downstream markers (MAML1, Hes1, and p21) are significantly upregulated after therapy. Knocking down LNX1 reverses these changes, causing a significant downregulation of Notch1 downstream marker Hes-1 (p &lt; .001). Furthermore, knocking down LNX1 reduced the frequency of GICs after TMZ therapy. The stem cell frequency in control cells was 1/128 as compared to 1/54 after therapy (p&lt;0.001). In comparison, LNX1 knockdown cells had a stem cell frequency of 1/84 as compared to 1/92 after TMZ therapy (p=0.84). Finally, based on The Cancer Genome Atlas data, LNX1 mRNA expression is negatively correlated with overall survival in patients with GBM (p=0.015). Taken together, we propose that therapeutic stress-induced LNX1 expression can alter the Notch pathway, which subsequently allows symmetric self-renewal to predominate in GBM and therefore provides a potentially valuable therapeutic target to prevent GBM recurrence.

Citation Format: Shivani Baisiwala, Robert Hall, Louisa Warnke, Anne Christensen, Jack Shireman, Cheol H. Park, Atique U. Ahmed. The role of symmetric cell division in post-therapy glioma-initiating cell expansion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4949.

Effect of drought stress on bio-chemical change and cell membrane stability of soybean genotypes

An experiment was conducted in a venylhouse at the environmental stress site of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during September to December 2012 to study the effect of drought stress on proline content, soluble sugar content, chlorophyll content and cell membrane stability of soybean genotypes. Four studied genotypes viz., Shohag, BARI Soybean-6 and BD2331 (relatively stress tolerant) and BGM2026 (susceptible) were tested against two water regimes such as water stress and non-stress. Results indicated that due to drought stress there was an increase in proline content and soluble sugar content and decrease in chlorophyll a content, chlorophyll b content, total chlorophyll content, chlorophyll a/b ratio and cell membrane stability. Proline and soluble sugar showed more content in tolerant genotype than in susceptible ones. Chlorophyll reduction was most significant and cell membrane stability was found minimal in susceptible genotypes. From the result, genotype BGM2026 which recorded the lowest proline, soluble sugar content and highest chlorophyll reduction and cell membrane injury was considered as drought susceptible. The variety/genotype of soybean such as BARI Soybean-6, Shohag and BD2331 were more drought stress tolerant and better mechanisms of drought tolerance.Bangladesh J. Agril. Res. 42(3): 475-485, September 2017

Dogs are man's best friend: in sickness and in health

With the median survival of 14.6 months following best available standard of care, malignant gliomas (MGs) remain one of the biggest therapeutic challenges of the modern time. Although the last several decades have witnessed tremendous advancement in our understanding of MG and evolution of many successful preclinical therapeutic strategies, even the most successful preclinical therapeutic strategies often fail to cross the phase I/II clinical trial threshold. One of the significant, but less commonly discussed, barriers in developing effective glioma therapy is the lack of a robust preclinical model. For the last 30 years, rodent orthotopic xenograft models have been extensively used in the preclinical setting. Although they provide a good basic model for understanding tumor biology, their value in successfully translating preclinical therapeutic triumph into clinical success is extremely poor. Companion dogs, which share the same environmental stress as their human counterparts, also spontaneously develop MGs. Dog gliomas that develop spontaneously in an immunocompetent host are very similar to human gliomas and potentially provide a stronger platform for validating the efficacy of therapeutic strategies proven successful in preclinical mouse models. Integrating this model can accelerate development of effective therapeutic options that will benefit both human subjects and pet dogs.

Abstract 4824: The “gatekeeper” function of Drosophila Seven-IN-Absentia (SINA) E3 ligase and its human homologs, SIAH1 and SIAH2, is highly conserved for proper RAS signal transduction in Drosophila development

Seven-IN-Absentia (SINA) is an evolutionarily conserved E3 ubiquitin ligase that is the most downstream signaling module identified in the RAS signal transduction cascade. Underscoring the importance of SINA is its high evolutionary conservation with over 83% amino acid identity shared between Drosophila SINA and its human SINA homologs (SIAHs). As a major signaling “gatekeeper” in the RAS pathway, we have shown that SIAH is required for oncogenic K-RAS-driven tumorigenesis and metastasis in human pancreatic, lung and breast cancer. Since SIAHs appear to be the ideal drug target to inhibit “undruggable” K-RAS activation, it is important to precisely characterize the activity, regulation, and substrate targeting mechanism(s) of this highly conserved family of SINA/SIAH E3 ligases. By deploying the elegant and well-established Drosophila development system, we are able to study RAS activation and SINA function under normal physiological conditions. In the developing Drosophila eye, photoreceptor cells are recruited sequentially and acquire their distinctive cell fates through a series of local inductive events. The 800x cell arrays allowed us to dissect the role of SINA/SIAH downstream of RAS activation in photoreceptor cell development. To delineate SINA function, we performed an F1 modifier screen using ethyl methanesulfonate (EMS) and X-ray radiation, isolating 28 novel sina mutant alleles. These mutant alleles exhibit much stronger mutant phenotypes than those of the previously published sina2 and sina3 alleles, suggesting that the sina2 and sina3 alleles are hypomorphic alleles. Sequencing analysis of these sinamutant alleles reveals the functional roles of mutated residues and protein domains. To define SINA/SIAH functional conservation, we have generated a complete panel of transgenic fly models that express either wild-type (WT) or dominant negative (DN) SINA/SIAH. The corresponding UAS-sina/siahGOF/LOF phenotypes have been characterized using sev-, GMR-, dpp- and salivary gland-GAL4 drivers to elucidate the developmental outcomes of altered SINA/SIAH expression upon RAS activation. Ectopic expression of sinaWT/DN/siahWT/DN in neurons resulted in dramatic changes in neuronal cell fate in the developing eye and notum, causing PNS neurodegenerative phenotypes. Our results show that the biological functions of fly SINA and human SIAH1/SIAH2 are evolutionarily conserved and functionally interchangeable. Mechanistic insights and regulatory principles learned from Drosophila can be directly applied to cancer biology to develop and validate next-generation anti-SIAH-based anti-K-RAS and anticancer therapy in the future.

Citation Format: Robert E. Van Sciver, Yajun Cao, Atique U. Ahmed, Amy H. Tang. The “gatekeeper” function of Drosophila Seven-IN-Absentia (SINA) E3 ligase and its human homologs, SIAH1 and SIAH2, is highly conserved for proper RAS signal transduction in Drosophila development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4824. doi:10.1158/1538-7445.AM2017-4824

Abstract 2888: Dopamine signaling and therapeutic resistance in GBM

Glioblastoma multiforme (GBM), the most common and aggressive primary brain tumor in adults, is characterized by aggressive recurrence after conventional treatment, which include surgery followed by radiation and chemotherapy. This recurrence reilies on GBM cells’ ability to promote therapeutic resistance. The recently developed Cancer Stem Cell (CSC) hypothesis argues that GBMs are driven by a rare subset of cells called Glioma Stem Cells (GSCs). A significant corollary of the CSC hypothesis is that GSCs have the ability to survive intensive radio- and chemotherapy and give rise to recurrent disease. Recent studies from our laboratory and others have shown a high degree of plasticity in GBM cells that indicated normal GBM cells acquire a stem-like state during anti-glioma therapy. Termed conversion, this molecular process increases the frequency of therapy resistant GSCs and promotes disease recurrence. We hypothesize that a drug capable of blocking tumor cell plasticity would prevent the generation of therapy-resistant GSCs, thereby block GBM recurrence. Based on this concept, we have developed a plasticity-based high-throughput drug screening method for GSCs. Our initial screening has identified several novel FDA-approved compounds that act as antagonists of neurotransmitter receptors. Further investigation revealed that treatment of patient-derived xenograft (PDX) GBM lines with temozolomide (TMZ) led to the formation of a population of cells that express both CD133, a marker of CSCs, and dopamine receptors 2 and 3 (DRDs) (control mean CD133+/DRD2+: 19.7%, TMZ mean: 83.8%, p=.0001). PDX lines treated with a dopamine receptor agonist exhibited increased expression of SOX2, OCT4 and c-Myc, GSC-markers. However, this treatment did not increase the expression of Ki67 in the GSC compartment, a marker for cell proliferation (mean DMSO: 63.8%, mean TMZ: 57.4%). Thus, DRD signaling may influence the plasticity driven GSC niche. Utilizing a CD133-reporter cell line, we found that two anti-psychotics, chlorprothioxene and loxapine, prevented the induction of CD133 expression caused by treatment with TMZ. Finally, we treated PDX lines with chlorpromazine, a newer version chlorprothioxene, in conjunction with TMZ, which resulted in increased therapeutic effecacy (p&lt;.0001 by MTT assay). Overall, these data suggest that dopamine receptor signaling and stress-induced cellular plasticity interact in GBM. We proposed that dopamine receptors represent a strategy by which specific molecular changes induces by canonical chemotherapeutic agents can be inhibited to prevent the induction of resistance in surviving cells.

Citation Format: Seamus P. Caragher, Cheol H. Park, Fatemeh Atashi, Shivani Baisiwala, Atique U. Ahmed. Dopamine signaling and therapeutic resistance in GBM [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2888. doi:10.1158/1538-7445.AM2017-2888

Rogue one: another faction of the Wnt empire implicated in assisting GBM progression

It remains incumbent on researchers to conceive novel treatments for the most common primary malignancy of the brain in adults, glioblastoma multiforme (GBM), as the standard of care for patients today fails to yield a median survival beyond two years following diagnosis. Recent studies have tended towards appreciating the cellular heterogeneity of GBM tumors, focusing on the subpopulation of highly plastic glioblastoma stem cells (GSCs). In the November 2016 issue of Cell, Hu and colleagues developed a de nova GBM model derived from immortalized neural stem cells and, using this model, they demonstrated that GSCs can generate CD133⁺/CD144⁺ cells with endothelial cell-like characteristics. Contrasts between the epigenetic state and gene expression level before and after oncogenic transformation of this utilized de novo model for GBM implicated WNT5A, which has been previously shown to play a role in endothelial cell proliferation and migration via non-canonical Wnt signaling, as a mediator of the process. The transdifferentiation was accompanied by alterations in the histone marks at the gene loci of WNT5A, and its transcription factors PAX6 and DXL5. The authors hypothesize that activation of AKT, an aberration of the RTK/PTEN/PI3K pathway observed in the majority of GBM cases, triggers these epigenetic changes causing WNT5A expression. This phenomenon is of obvious clinical significance, as it provides an insight into how GBM may circumvent therapies targeting angiogenesis to achieve the neovascularization required to sustain invasive growth. The unveiling of this atypical differentiation process also raises questions about its interaction with the radiotherapy and chemotherapy commonly used to counter GBM progression. Here, we review the recent efforts to understand the complex mechanisms behind the plasticity of GSCs.

Cancer Stem Cells: Cellular Plasticity, Niche, and its Clinical Relevance

Cancer handles an estimated 7.6 million deaths worldwide per annum. A recent theory focuses on the role Cancer Stem Cells (CSCs) in driving tumorigenesis and disease progression. This theory hypothesizes that a population of the tumor cell with similar functional and phenotypic characteristics as normal tissue stem cells are responsible for formation and advancement of many human cancers. The CSCs subpopulation can differentiate into non-CSC tumor cells and promote phenotypic and functional heterogeneity within the tumor. The presence of CSCs has been reported in a number of human cancers including blood, breast, brain, colon, lung, pancreas prostate and liver. Although the origin of CSCs remains a mystery, recent reports suggest that the phenotypic characteristics of CSCs may be plastic and are influenced by the microenvironment specific for the individual tumor. Such factors unique to each tumor preserve the dynamic balance between CSCs to non-CSCs cell fate, as well as maintain the proper equilibrium. Alternating such equilibrium via dedifferentiation can result in aggressiveness, as CSCs are considered to be more resistant to the conventional cancer treatments of chemotherapy and radiation. Understanding how the tumoral microenvironment affects the plasticity driven CSC niche will be critical for developing a more effective treatment for cancer by eliminating its aggressive and recurring nature that now is believed to be perpetuated by CSCs.

Dysregulation of Aromatase in Breast, Endometrial, and Ovarian Cancers: An Overview of Therapeutic Strategies

Aromatase is the rate-limiting enzyme in the biosynthesis of estrogens, which play crucial roles on a spectrum of developmental and physiological processes. The biological actions of estrogens are classically mediated by binding to two estrogen receptors (ERs), ERα and ERβ. Encoded by the cytochrome P450, family 19, subfamily A, polypeptide 1 (CYP19A1) gene, aromatase is expressed in a wide variety of tissues, as well as benign and malignant tumors, and is regulated in a pathway- and tissue-specific manner. Overexpression of aromatase, leading to elevated systemic levels of estrogen, is unequivocally linked to the pathogenesis and growth of a number malignancies, including breast, endometrium, and ovarian cancers. Aromatase inhibitors (AIs) are routinely used to treat estrogen-dependent breast cancers in postmenopausal women; however, their roles in endometrial and ovarian cancers remain obscure. While AI therapy is effective in hormone sensitive cancers, they diminish estrogen production throughout the body and, thus, generate undesirable side effects. Despite the effectiveness of AI therapy, resistance to endocrine therapy remains a major concern and is the leading cause of cancer death. Considerable advances, toward mitigating these issues, have evolved in conjunction with a number of histone deacetylase (HDAC) inhibitors for countering an assortment of diseases and cancers, including the aforesaid malignancies. HDACs are a family of enzymes that are frequently dysregulated in human tumors. This chapter will discuss the current understanding of aberrant regulation and expression of aromatase in breast, endometrial, and ovarian cancers, and potential therapeutic strategies for prevention and treatment of these life-threatening diseases.

Dedifferentiation of Glioma Cells to Glioma Stem-like Cells By Therapeutic Stress-induced HIF Signaling in the Recurrent GBM Model

Increasing evidence exposes a subpopulation of cancer cells, known as cancer stem cells (CSCs), to be critical for the progression of several human malignancies, including glioblastoma multiforme. CSCs are highly tumorigenic, capable of self-renewal, and resistant to conventional therapies, and thus considered to be one of the key contributors to disease recurrence. To elucidate the poorly understood evolutionary path of tumor recurrence and the role of CSCs in this process, we developed patient-derived xenograft glioblastoma recurrent models induced by anti-glioma chemotherapy, temozolomide. In this model, we observed a significant phenotypic shift towards an undifferentiated population. We confirmed these findings in vitro as sorted CD133-negative populations cultured in differentiation-forcing media were found to acquire CD133 expression following chemotherapy treatment. To investigate this phenotypic switch at the single-cell level, glioma stem cell (GSC)-specific promoter-based reporter systems were engineered to track changes in the GSC population in real time. We observed the active phenotypic and functional switch of single non-stem glioma cells to a stem-like state and that temozolomide therapy significantly increased the rate of single-cell conversions. Importantly, we showed the therapy-induced hypoxia-inducible factors (HIF) 1α and HIF2α play key roles in allowing non-stem glioma cells to acquire stem-like traits, as the expression of both HIFs increase upon temozolomide therapy and knockdown of HIFs expression inhibits the interconversion between non-stem glioma cells and GSCs post-therapy. On the basis of our results, we propose that anti-glioma chemotherapy promotes the accumulation of HIFs in the glioblastoma multiforme cells that induces the formation of therapy-resistant GSCs responsible for recurrence. Mol Cancer Ther; 15(12); 3064-76. ©2016 AACR.

Intranasal Oncolytic Virotherapy with CXCR4-Enhanced Stem Cells Extends Survival in Mouse Model of Glioma

The challenges to effective drug delivery to brain tumors are twofold: (1) there is a lack of non-invasive methods of local delivery and (2) the blood-brain barrier limits systemic delivery. Intranasal delivery of therapeutics to the brain overcomes both challenges. In mouse model of malignant glioma, we observed that a small fraction of intranasally delivered neural stem cells (NSCs) can migrate to the brain tumor site. Here, we demonstrate that hypoxic preconditioning or overexpression of CXCR4 significantly enhances the tumor-targeting ability of NSCs, but without altering their phenotype only in genetically modified NSCs. Modified NSCs deliver oncolytic virus to glioma more efficiently and extend survival of experimental animals in the context of radiotherapy. Our findings indicate that intranasal delivery of stem cell-based therapeutics could be optimized for future clinical applications, and allow for safe and repeated administration of biological therapies to brain tumors and other CNS disorders.

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Intranasal delivery of NSCs is a promising platform for glioma therapy

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Hypoxia or CXCR4 overexpression enhances NSC migration to glioma

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Oncolytic viruses loaded in CXCR4-enhanced NSCs improve animal survival

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Non-invasive intranasal NSC-based therapies warrant clinical translation

CCL2 Produced by the Glioma Microenvironment Is Essential for the Recruitment of Regulatory T Cells and Myeloid-Derived Suppressor Cells

In many aggressive cancers, such as glioblastoma multiforme, progression is enabled by local immunosuppression driven by the accumulation of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC). However, the mechanistic details of how Tregs and MDSCs are recruited in various tumors are not yet well understood. Here we report that macrophages and microglia within the glioma microenvironment produce CCL2, a chemokine that is critical for recruiting both CCR4⁺ Treg and CCR2⁺Ly-6C⁺ monocytic MDSCs in this disease setting. In murine gliomas, we established novel roles for tumor-derived CCL20 and osteoprotegerin in inducing CCL2 production from macrophages and microglia. Tumors grown in CCL2-deficient mice failed to maximally accrue Tregs and monocytic MDSCs. In mixed-bone marrow chimera assays, we found that CCR4-deficient Treg and CCR2-deficient monocytic MDSCs were defective in glioma accumulation. Furthermore, administration of a small-molecule antagonist of CCR4 improved median survival in the model. In clinical specimens of glioblastoma multiforme, elevated levels of CCL2 expression correlated with reduced overall survival of patients. Finally, we found that CD163-positive infiltrating macrophages were a major source of CCL2 in glioblastoma multiforme patients. Collectively, our findings show how glioma cells influence the tumor microenvironment to recruit potent effectors of immunosuppression that drive progression. Cancer Res; 76(19); 5671-82. ©2016 AACR.

Effect of drought stress on gas exchange characteristics of four soybean genotypes

An experiment was conducted in a venylhouse at the environmental stress site of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during September to December 2012 to determine the changes of photosynthesis and some related traits under drought stress in soybean genotypes. Four studied genotypes viz. Shohag, BARI Soybean 6 and BD2331 (relatively stress tolerant) and BGM2026 (susceptible) were tested against two water regimes such as water stress and non-stress. Results indicated that gas exchange characteristics were positively correlated with plant growth. Photosynthesis and stomatal conductance showed more reduction in susceptible genotypes than the tolerant ones. Transpiration rate was found minimal in tolerant genotypes. Changes in leaf growth attributes of the four selected genotypes were compared under drought (water) stress conditions which is one of the major plant parts related to gas exchange. Generally, drought stress decreased the leaf area more in susceptible genotype than tolerant genotype. From the result, genotype BGM2026 which recorded the lowest photosynthesis, stomatal conductance, leaf area but highest transpiration rate was considered as drought susceptible whereas BARI Soybean-6, Shohag and BD2331 were more drought stress tolerant which have better mechanisms of drought tolerance.Bangladesh J. Agril. Res. 41(2): 195-205, June 2016

Single dose GLP toxicity and biodistribution study of a conditionally replicative adenovirus vector, CRAd-S-pk7, administered by intracerebral injection to Syrian hamsters

Background

CRAd-S-pk7 is a conditionally replicative oncolytic adenoviral vector that contains a survivin promoter and a pk7 fiber modification that confer tumor-specific transcriptional targeting and preferential replication in glioma while sparing the surrounding normal brain parenchyma.

Methods

This IND-enabling study performed under GLP conditions evaluated the toxicity and biodistribution of CRAd-S-pk7 administered as a single intracerebral dose to Syrian hamsters, a permissive model of adenoviral replication. Two hundred and forty animals were stereotactically administered either vehicle (n = 60) or CRAd-S-pk7 at 2.5 × 10⁷, 2.5 × 10⁸, or 2.5 × 10⁹ viral particles (vp)/animal (each n = 60) on day 1. The animals were closely monitored for toxicology evaluation, assessment of viral distribution, and immunogenicity of CRAd-S-pk7.

Results

Changes in hematology, clinical chemistry, and coagulation parameters were minor and transient, and consistent with the inflammatory changes observed microscopically. These changes were considered to be of little toxicological significance. The vector remained localized primarily in the brain and to some degree in the tissues at the incision site. Low levels of vector DNA were detected in other tissues in a few animals suggesting systemic circulation of the virus. Viral DNA was detected in brains of hamsters for up to 62 days. However, microscopic changes and virus-related toxicity to the central nervous system were considered minor and decreased in incidence and severity over time. Such changes are not uncommon in studies using adenoviral vectors.

Conclusion

This study provides safety and toxicology data justifying a clinical trial of CRAd-S-pk7 loaded in FDA-approved HB1.F3.CD neural stem cell carriers administered at the tumor resection bed in humans with recurrent malignant glioma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0895-8) contains supplementary material, which is available to authorized users.

Stem Cell-Based Cell Carrier for Targeted Oncolytic Virotherapy: Translational Opportunity and Open Questions

Oncolytic virotherapy for cancer is an innovative therapeutic option where the ability of a virus to promote cell lysis is harnessed and reprogrammed to selectively destroy cancer cells. Such treatment modalities exhibited antitumor activity in preclinical and clinical settings and appear to be well tolerated when tested in clinical trials. However, the clinical success of oncolytic virotherapy has been significantly hampered due to the inability to target systematic metastasis. This is partly due to the inability of the therapeutic virus to survive in the patient circulation, in order to target tumors at distant sites. An early study from various laboratories demonstrated that cells infected with oncolytic virus can protect the therapeutic payload form the host immune system as well as function as factories for virus production and enhance the therapeutic efficacy of oncolytic virus. While a variety of cell lineages possessed potential as cell carriers, copious investigation has established stem cells as a very attractive cell carrier system in oncolytic virotherapy. The ideal cell carrier desire to be susceptible to viral infection as well as support viral infection, maintain immunosuppressive properties to shield the loaded viruses from the host immune system, and most importantly possess an intrinsic tumor homing ability to deliver loaded viruses directly to the site of the metastasis—all qualities stem cells exhibit. In this review, we summarize the recent work in the development of stem cell-based carrier for oncolytic virotherapy, discuss the advantages and disadvantages of a variety of cell carriers, especially focusing on why stem cells have emerged as the leading candidate, and finally propose a future direction for stem cell-based targeted oncolytic virotherapy that involves its establishment as a viable treatment option for cancer patients in the clinical setting.

A Genetically Modified Adenoviral Vector with a Phage Display-Derived Peptide Incorporated into Fiber Fibritin Chimera Prolongs Survival in Experimental Glioma

The dismal clinical context of advanced-grade glioma demands the development of novel therapeutic strategies with direct patient impact. Adenovirus-mediated virotherapy represents a potentially effective approach for glioma therapy. In this research, we generated a novel glioma-specific adenovirus by instituting more advanced genetic modifications that can maximize the efficiency and safety of therapeutic adenoviral vectors. In this regard, a glioma-specific targeted fiber was developed through the incorporation of previously published glioma-specific, phage-panned peptide (VWT peptide) on a fiber fibritin-based chimeric fiber, designated as "GliomaFF." We showed that the entry of this virus was highly restricted to glioma cells, supporting the specificity imparted by the phage-panned peptide. In addition, the stability of the targeting moiety presented by fiber fibritin structure permitted greatly enhanced infectivity. Furthermore, the replication of this virus was restricted in glioma cells by controlling expression of the E1 gene under the activity of the tumor-specific survivin promoter. Using this approach, we were able to explore the combinatorial efficacy of various adenoviral modifications that could amplify the specificity, infectivity, and exclusive replication of this therapeutic adenovirus in glioma. Finally, virotherapy with this modified virus resulted in up to 70% extended survival in an in vivo murine glioma model. These data demonstrate that this novel adenoviral vector is a safe and efficient treatment for this difficult malignancy.

Neural Stem Cells Secreting Anti-HER2 Antibody Improve Survival in a Preclinical Model of HER2 Overexpressing Breast Cancer Brain Metastases

The treatment of human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer has been revolutionized by trastuzumab. However, longer survival of these patients now predisposes them to forming HER2 positive brain metastases, as the therapeutic antibodies cannot cross the blood brain barrier. The current oncologic repertoire does not offer a rational, nontoxic targeted therapy for brain metastases. In this study, we used an established human neural stem cell line, HB1.F3 NSCs and generated a stable pool of cells secreting a high amount of functional full-length anti-HER2 antibody, equivalent to trastuzumab. Anti-HER2Ab secreted by the NSCs (HER2Ab-NSCs) specifically binds to HER2 overexpressing human breast cancer cells and inhibits PI3K-Akt signaling. This translates to HER2Ab-NSC inhibition of breast cancer cell growth in vitro. Preclinical in vivo experiments using HER2Ab overexpressing NSCs in a breast cancer brain metastases (BCBM) mouse model demonstrate that intracranial injection of HER2Ab-NSCs significantly improves survival. In effect, these NSCs provide tumor localized production of HER2Ab, minimizing any potential off-target side effects. Our results establish HER2Ab-NSCs as a novel, nontoxic, and rational therapeutic approach for the successful treatment of HER2 overexpressing BCBM, which now warrants further preclinical and clinical investigation.