Reshaping the tumor microenvironment with oncolytic viruses, positive regulation of the immune synapse, and blockade of the immunosuppressive oncometabolic circuitry

BACKGROUND

Oncolytic viruses are considered part of immunotherapy and have shown promise in preclinical experiments and clinical trials. Results from these studies have suggested that tumor microenvironment remodeling is required to achieve an effective response in solid tumors. Here, we assess the extent to which targeting specific mechanisms underlying the immunosuppressive tumor microenvironment optimizes viroimmunotherapy.

METHODS

We used RNA-seq analyses to analyze the transcriptome, and validated the results using Q-PCR, flow cytometry, and immunofluorescence. Viral activity was analyzed by replication assays and viral titration. Kyn and Trp metabolite levels were quantified using liquid chromatography-mass spectrometry. Aryl hydrocarbon receptor (AhR) activation was analyzed by examination of promoter activity. Therapeutic efficacy was assessed by tumor histopathology and survival in syngeneic murine models of gliomas, including Indoleamine 2,3-dioxygenase (IDO)-/- mice. Flow cytometry was used for immunophenotyping and quantification of cell populations. Immune activation was examined in co-cultures of immune and cancer cells. T-cell depletion was used to identify the role played by specific cell populations. Rechallenge experiments were performed to identify the development of anti-tumor memory.

RESULTS

Bulk RNA-seq analyses showed the activation of the immunosuppressive IDO-kynurenine-AhR circuitry in response to Delta-24-RGDOX infection of tumors. To overcome the effect of this pivotal pathway, we combined Delta-24-RGDOX with clinically relevant IDO inhibitors. The combination therapy increased the frequency of CD8+ T cells and decreased the rate of myeloid-derived suppressor cell and immunosupressive Treg tumor populations in animal models of solid tumors. Functional studies demonstrated that IDO-blockade-dependent activation of immune cells against tumor antigens could be reversed by the oncometabolite kynurenine. The concurrent targeting of the effectors and suppressors of the tumor immune landscape significantly prolonged the survival in animal models of orthotopic gliomas.

CONCLUSIONS

Our data identified for the first time the in vivo role of IDO-dependent immunosuppressive pathways in the resistance of solid tumors to oncolytic adenoviruses. Specifically, the IDO-Kyn-AhR activity was responsible for the resurface of local immunosuppression and resistance to therapy, which was ablated through IDO inhibition. Our data indicate that combined molecular and immune therapy may improve outcomes in human gliomas and other cancers treated with virotherapy.

Oncolytic DNX-2401 Virus for Pediatric Diffuse Intrinsic Pontine Glioma

BACKGROUND

Pediatric patients with diffuse intrinsic pontine glioma (DIPG) have a poor prognosis, with a median survival of less than 1 year. Oncolytic viral therapy has been evaluated in patients with pediatric gliomas elsewhere in the brain, but data regarding oncolytic viral therapy in patients with DIPG are lacking.

METHODS

We conducted a single-center, dose-escalation study of DNX-2401, an oncolytic adenovirus that selectively replicates in tumor cells, in patients with newly diagnosed DIPG. The patients received a single virus infusion through a catheter placed in the cerebellar peduncle, followed by radiotherapy. The primary objective was to assess the safety and adverse-event profile of DNX-2401. The secondary objectives were to evaluate the effect of DNX-2401 on overall survival and quality of life, to determine the percentage of patients who have an objective response, and to collect tumor-biopsy and peripheral-blood samples for correlative studies of the molecular features of DIPG and antitumor immune responses.

RESULTS

A total of 12 patients, 3 to 18 years of age, with newly diagnosed DIPG received 1×1010 (the first 4 patients) or 5×1010 (the subsequent 8 patients) viral particles of DNX-2401, and 11 received subsequent radiotherapy. Adverse events among the patients included headache, nausea, vomiting, and fatigue. Hemiparesis and tetraparesis developed in 1 patient each. Over a median follow-up of 17.8 months (range, 5.9 to 33.5), a reduction in tumor size, as assessed on magnetic resonance imaging, was reported in 9 patients, a partial response in 3 patients, and stable disease in 8 patients. The median survival was 17.8 months. Two patients were alive at the time of preparation of the current report, 1 of whom was free of tumor progression at 38 months. Examination of a tumor sample obtained during autopsy from 1 patient and peripheral-blood studies revealed alteration of the tumor microenvironment and T-cell repertoire.

CONCLUSIONS

Intratumoral infusion of oncolytic virus DNX-2401 followed by radiotherapy in pediatric patients with DIPG resulted in changes in T-cell activity and a reduction in or stabilization of tumor size in some patients but was associated with adverse events. (Funded by the European Research Council under the European Union's Horizon 2020 Research and Innovation Program and others; EudraCT number, 2016-001577-33; ClinicalTrials.gov number, NCT03178032.).

Abstract 4184: RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism

Viroimmunotherapy aims to infect cancer cells to elicit anti-tumor immune responses. In clinical trials, glioma treatment with oncolytic viruses induced durable clinical responses in a small fraction of patients. To improve the percentage of responders, it is necessary to reshape the tumor microenvironment that shields the tumor from the immune system of the patient. Thus, we engineered Delta-24-RGDOX (DNX-2440), an oncolytic adenovirus that carries the cDNA of the T-cell activator, OX40L. In this work, we observed that Delta-24-RGDOX triggered a dramatic reshaping of the tumor microenvironment dominated by strong changes in immune processes as indicated by RNA-sequencing via ingenuity pathway analyses in a murine glioblastoma model. Paradoxically, network analyses revealed that Delta-24-RGDOX also induced robust activation of the cytokine-driven immunosuppressive IDO-Kynurenine-AhR circuitry, indicating a potential mechanism of resistance of the cancer cells to oncolytic virotherapy. To reverse this immunosuppression, we combined Delta-24-RGDOX with clinically relevant IDO inhibitors to treat glioma bearing mice. Importantly, addition of the IDO inhibitor to Delta-24-RGDOX decreased the activation of the IDO network. IDO inhibition did not affect virus infection or replication in human or murine glioma cells. Flow cytometry assays revealed that the combination therapy increased the frequency of activated CD8+ T cells and decreased the presence of the immunosuppressive cell populations, MDSCs and Tregs. Gene set enrichment analyses confirmed the decrease of MDSCs and Tregs in the combination treated glioma-bearing mice compared to the virus alone. Functional co-culture studies showed that the combined therapy activated splenocytes against tumor antigens, and that this activation was reversed by kynurenine. Importantly, the combination treatment eradicated the tumors in a CD4-dependent manner and significantly prolonged the survival of glioma-bearing mice. Altogether, these studies indicate that the combination treatment promotes an adaptive immune response while decreasing immunosuppression caused by virus-induced IDO activation. Furthermore, our data identified the striking role of immunosuppressive pathways in the resistance of gliomas to oncolytic virotherapy. Specifically, the activity of the tumor microenvironment IDO circuitry was responsible, at least partially, for the remodeling of local immunosuppression after tumor infection. Combining molecular and immune-related therapies may improve outcomes in human gliomas treated with virotherapy.

Citation Format: Teresa T. Nguyen, Dong Ho Shin, Sagar Sohoni, Sanjay K. Singh, Yisel Rivera-Molina, Hong Jiang, Xuejun Fan, Joy Gumin, Frederick F. Lang, Christopher Alvarez-Breckenridge, Marta M. Alonso, Filipa Godoy-Vitorino, Lijie Zhai, Erik Ladomersky, Kristen L. Lauing, Derek A. Wainwright, Juan Fueyo, Candelaria Gomez-Manzano. RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4184.

Abstract 3565: Viroimmunotherapy for solid tumors results in local and abscopal anti-cancer effects and the remodeling of tumor microenvironment

Oncolytic viruses are a promising experimental treatment for solid tumors. Recently, several phase 1 clinical trials have reported encouraging therapeutic effects of oncolytic viruses in adult and pediatric patients with malignant gliomas. To further improve the therapeutic outcome of viroimmunotherapy, we have developed Delta-24-RGDOX (DNX-2440), a replication competent adenovirus encompassing the T-cell activator OX40L in the genetic backbone of Delta-24-RGD. We have previously reported the effect of Delta-24-RGDOX in murine brain tumors supporting the translation of this new agent to treat patients with recurrent malignant gliomas (NCT03714334). In the work presented here, we have tested the therapeutic effect of Delta-24-RGDOX in murine syngeneic models of breast (4T1), gastric (M12) and lung cancer (LLC and CMT 167). We found that Delta-24-RGDOX infected all cancer cell lines efficiently. In addition, infection of cells was followed by the expression of the ectopic ligand in vitro and in vivo. Because the elicitation of an anti-tumor immunity is part of the mechanisms underlying the therapeutic effect of oncolytic viruses, we examined whether infection of tumors led to the reshaping of the tumor microenvironment. We observed that Delta-24-RGDOX infection was followed by increased frequencies of tumor infiltrating lymphocytes, particularly CD8+ T cells and NK cells. In addition, the CD8+/CD4+ ratio was increased in Delta-24-RGDOX-treated tumor versus PBS-treated tumors. Interestingly, abscopal modifications were observed in breast cancer brain metastases with increased frequency of CD8+ T cells at the distal, untreated site. Delta-24-RGDOX treatment induced an anti-cancer effect in orthotopically implanted breast cancer and subcutaneously implanted lung and gastric tumors, as well as in metastatic niches. In summary, our data showed that treatment of solid tumors with Delta-24-RGDOX induces robust remodeling of the tumor microenvironment and produces anti-tumor effects leading to decrease in tumor volume, along with a delay in the development and in the reduction of the number of metastases. These data suggest that Delta-24-RGDOX should be tested in the clinical setting in patients with metastatic breast, gastric and lung cancers.

Citation Format: Arie C. Van Wieren, Sagar Sahoni, Teresa Nguyen, Ashley Ossimetha, Yisel Rivera-Molina, Hong Jiang, Dong Ho Shin, Debora Kim, Xuejun Fan, Yanhua Yi, Natalie M. Melendez-Vazquez, Filipa Godoy-Vitorino, Joy Gumin, Frederick F. Lang, Marta M. Alonso, Juan Fueyo, Candelaria Gomez-Manzano. Viroimmunotherapy for solid tumors results in local and abscopal anti-cancer effects and the remodeling of tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3565.

Abstract 3569: Combining oncolytic adenovirus Delta-24-RGDOX with adoptive T cell therapy in localized treatment induces sustainable regression of disseminated solid tumors through antigen spreading

CAR T therapy greatly improves the survival of patients with hematological malignancies. But its effect in solid tumors is suboptimal. Intratumoral injections of oncolytic viruses, including Delta-24-RGDOX (DNX-2440) from our group, directly lyse cancer cells and activate tumor microenvironment, leading to adaptive antitumor immunity. To take advantage of instant antitumor activity of T cells and virus-mediated in situ autovaccination against heterogeneous cancer cells, we hypothesize that intratumorally injections of tumor-targeting T cells followed by Delta-24-RGDOX overcome antigen escape of CAR T therapy, leading to more sustainable systemic anti-cancer immunity. Thus, we used subcutaneous (s.c.)/s.c. B16 melanoma mouse models to assess the effect of localized treatment in disseminated tumors. OVA (or gp100)-specific CD8+ T cells or CD19 CAR T cells were injected into the first tumor, followed by three injections of Delta-24-RGDOX into the same tumor. T cells and tumor cells from the mice were profiled for surface markers with flow cytometry and immune staining. Activity of splenocytes against tumor cells and specific tumor-associated-antigens (TAAs) was measured with ELISA. Tumor growth was monitored through measuring tumor size. The animal survival curves were plotted according to the Kaplan-Meier method. We found TAA-specific T cells injected into the first s.c. tumor showed tropism for disseminated s.c. and intracranial tumors, tumor draining lymph nodes, but not for spleen, peripheral blood and normal brain. Unlike untreated and Delta-24-RGDOX-treated tumor, T cell-treated tumor showed decreased expression of the target TAA which was depleted in the recurrent tumor. Moreover, Delta-24-RGDOX increased total T cell presence within the tumors, and the activity of the splenocytes against the tumor cells and other antigens than the one targeted by injected T cells. Consequentially, the combination of OVA-specific T cells and Delta-24-RGDOX was more potent to inhibit the injected and untreated disseminated tumor growth and caused improved survival rate than either of the agent alone (p < 0.05). Importantly, we observed relapse of the regressed tumors in the group treated by T cells alone, but not in the combination group. The survivors from the combination therapy were protected from rechallenging with B16-OVA cells but not lung carcinoma cells, suggesting the development of immune memory. In summary, our study indicates the virus induces antigen spread, resulting in expansion of antitumor T cell repertoire to prevent cancer relapse in adoptive T cell therapy (ACT). Our data demonstrate that Delta-24-RGDOX collaborates with ACT to induce more potent systemic immunity against the tumors, leading to sustainable tumor regression.

Citation Format: Hong Jiang, Dong Ho Shin, Yanhua Yi, Xuejun Fan, Joy Gumin, Marta M. Alonso, Frederick F. Lang, Candelaria Gomez-Manzano, Juan Fueyo. Combining oncolytic adenovirus Delta-24-RGDOX with adoptive T cell therapy in localized treatment induces sustainable regression of disseminated solid tumors through antigen spreading [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3569.

Abstract 2540: A multi-dimensional analysis of human gliomas at the single cell level identifies immune suppressive macrophage molecular signatures and a novel immunotherapy target for GBM

Glioblastoma (GBM) is the most prevalent primary brain malignancy in adults. The current standard of care includes maximal surgical resection followed by radio- and chemotherapy with temozolomide. Yet <5% of GBM patients survive more than five years. This indicates a desperate need for more effective treatments, such as immunotherapy for GBM patients. Unfortunately, most immunotherapy trials, including vaccines, adoptive cellular therapy, CAR-T cells, and checkpoint blockade, showed only modest benefits in GBM patients. A major barrier to immunotherapy efficacy is GBM’s immunosuppressive microenvironment composed of few tumor infiltrating lymphocytes (TILs; <5%) but abundant myeloid cells, making it an immune cold tumor. By contrast, immune hot tumors, characterized by abundant tumoricidal effector T cells necessary to mount a meaningful attack, have consistently responded better to immunotherapy. Hence, a better definition of the heterogeneous cell types in the GBM microenvironment and their function is urgently needed. Fortunately, single cell transcriptomics approaches provide comprehensive and high-resolution cellular and molecular understanding to resolve this heterogeneity. Here we report an integrated, multiregional and -dimensional single cell transcriptomic analysis of 201,986 human glioma and immune cells derived from 44 tissue fragments from 18 human glioma patients. In doing so, we map GBM cellular heterotypia and spatial, molecular, and functional heterogeneity of glioma associated immune cells. We report extensive spatial and molecular heterogeneity of glioma cells, microglia, macrophages, and T cells within the same tumor samples in low grade gliomas, primary GBMs, and recurrent GBMs. Importantly, our analysis of 83,479 glioma infiltrating myeloid cells identifies 9 molecularly distinct myeloid subtypes: 4 microglial, 4 bone marrow derived macrophage and dendritic cells subtypes. Importantly, in multiple independent glioma patient cohorts, 5 of these myeloid cell subtype gene signatures were independent predictors of patient survival. We also provide evidence that cell:cell communication between glioma and immune cells is more robust than glioma:Tcells, indicating that myeloid cells form a communication hub in vivo. Additionally, we identified S100A4 as highly expressed in immunosuppressive macrophages and T cells, and provide in vitro and in vivo evidence that S100a4 plays a critical role in promoting immunosuppressive phenotypes in glioma associated leukocytes. This study not only provides the first comprehensive single cell atlas of GBM to include both glioma and immune cells from same samples but also demonstrates its utility in elucidating cell:cell communication among different cell types in vivo and discovering new therapeutic targets for this poorly immunogenic cancer.

Citation Format: Nourhan Abdelfattah, Parveen Kumar, Caiyi Wang, Jia-Shiun Leu, William W. Flynn, Ruli Gao, David S. Baskin, Kumar Pichumani, Omkar B. Ijare, Stephanie Wood, Suzanne Powell, David Haviland, Frederick F. Lang, Sujit Prabhu, Kristin Huntoon, Brittany C. Parker Kerrigan, Wen Jiang Jiang, Betty Y. Kim, Joshy George, Kyuson Yun. A multi-dimensional analysis of human gliomas at the single cell level identifies immune suppressive macrophage molecular signatures and a novel immunotherapy target for GBM [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2540.

A Window of Opportunity to Overcome Therapeutic Failure in Neuro-Oncology

Glioblastoma is the most common primary malignant brain neoplasm and it remains one of the most difficult-to-treat human cancers despite decades of discovery and translational and clinical research. Many advances have been made in our understanding of the genetics and epigenetics of gliomas in general; yet, there remains an urgent need to develop novel agents that will improve the survival of patients with this deadly disease. What sets glioblastoma apart from all other cancers is that it develops and spreads within an organ that renders tumor cells inaccessible to most systemically administered agents because of the presence of the blood-brain barrier. Inadequate drug penetration into the central nervous system is often cited as the most common cause of trial failure in neuro-oncology, and even so-called brain-penetrant therapeutics may not reach biologically relevant concentrations in tumor cells. Evaluation of the pharmacokinetics and pharmacodynamics of a novel therapy is a cornerstone of drug development, but few trials for glioma therapeutics have incorporated these basic elements in an organ-specific manner. Window-of-opportunity clinical trial designs can provide early insight into the biological plausibility of a novel therapeutic strategy in the clinical setting. A variety of window-of-opportunity trial designs, which take into account the limited access to treated tissue and the challenges with obtaining pretreatment control tissues, have been used for the initial development of traditional and targeted small-molecule drugs and biologic therapies, including immunotherapies and oncolytic viral therapies. Early-stage development of glioma therapeutics should include a window-of-opportunity component whenever feasible.

Convection Enhanced Delivery of the Oncolytic Adenovirus Delta24-RGD in Patients with Recurrent GBM: A Phase I Clinical Trial Including Correlative Studies

PURPOSE

Testing safety of Delta24-RGD (DNX-2401), an oncolytic adenovirus, locally delivered by convection enhanced delivery (CED) in tumor and surrounding brain of patients with recurrent glioblastoma.

PATIENTS AND METHODS

Dose-escalation phase I study with 3+3 cohorts, dosing 107 to 1 × 1011 viral particles (vp) in 20 patients. Besides clinical parameters, adverse events, and radiologic findings, blood, cerebrospinal fluid (CSF), brain interstitial fluid, and excreta were sampled over time and analyzed for presence of immune response, viral replication, distribution, and shedding.

RESULTS

Of 20 enrolled patients, 19 received the oncolytic adenovirus Delta24-RGD, which was found to be safe and feasible. Four patients demonstrated tumor response on MRI, one with complete regression and still alive after 8 years. Most serious adverse events were attributed to increased intracranial pressure caused by either an inflammatory reaction responding to steroid treatment or viral meningitis being transient and self-limiting. Often viral DNA concentrations in CSF increased over time, peaking after 2 to 4 weeks and remaining up to 3 months. Concomitantly Th1- and Th2-associated cytokine levels and numbers of CD3+ T and natural killer cells increased. Posttreatment tumor specimens revealed increased numbers of macrophages and CD4+ and CD8+ T cells. No evidence of viral shedding in excreta was observed.

CONCLUSIONS

CED of Delta24-RGD not only in the tumor but also in surrounding brain is safe, induces a local inflammatory reaction, and shows promising clinical responses.

HSP90-CDC37 functions as a chaperone for the oncogenic FGFR3-TACC3 fusion

The FGFR3-TACC3 (F3-T3) fusion gene was discovered as an oncogenic molecule in glioblastoma and bladder cancers, and has subsequently been found in many cancer types. Notably, F3-T3 was found to be highly expressed in both untreated and matched recurrence glioblastoma under the concurrent radiotherapy and temozolomide (TMZ) treatment, suggesting that targeting F3-T3 is a valid strategy for treatment. Here, we show that the F3-T3 protein is a client of heat shock protein 90 (HSP90), forming a ternary complex with the cell division cycle 37 (CDC37). Deprivation of HSP90 or CDC37 disrupts the formation of the ternary complex, which destabilizes glycosylated F3-T3, and thereby suppresses F3-T3 oncogenic activity. Gliomas harboring F3-T3 are resistant to TMZ chemotherapy. HSP90 inhibitors sensitized F3-T3 glioma cells to TMZ via the inhibition of F3-T3 activation and potentiated TMZ-induced DNA damage. These results demonstrate that F3-T3 oncogenic function is dependent on the HSP90 chaperone system and suggests a new clinical option for targeting this genetic aberration in cancer.

Single-cell analysis of human glioma and immune cells identifies S100A4 as an immunotherapy target

A major rate-limiting step in developing more effective immunotherapies for GBM is our inadequate understanding of the cellular complexity and the molecular heterogeneity of immune infiltrates in gliomas. Here, we report an integrated analysis of 201,986 human glioma, immune, and other stromal cells at the single cell level. In doing so, we discover extensive spatial and molecular heterogeneity in immune infiltrates. We identify molecular signatures for nine distinct myeloid cell subtypes, of which five are independent prognostic indicators of glioma patient survival. Furthermore, we identify S100A4 as a regulator of immune suppressive T and myeloid cells in GBM and demonstrate that deleting S100a4 in non-cancer cells is sufficient to reprogram the immune landscape and significantly improve survival. This study provides insights into spatial, molecular, and functional heterogeneity of glioma and glioma-associated immune cells and demonstrates the utility of this dataset for discovering therapeutic targets for this poorly immunogenic cancer.

Disruption of DNA Repair and Survival Pathways through Heat Shock Protein inhibition by Onalespib to Sensitize Malignant Gliomas to Chemoradiation therapy

PURPOSE

Proficient DNA repair by homologous recombination (HR) facilitates resistance to chemo-radiation in glioma stem cells (GSCs). We evaluated whether compromising HR by targeting HSP90, a molecular chaperone required for the function of key HR proteins, using onalespib, a long-acting, brain-penetrant HSP90 inhibitor, would sensitize high-grade gliomas to chemo-radiation in vitro and in vivo Experimental Design: The ability of onalespib to deplete HR client proteins, impair HR repair capacity, and sensitize GBM to chemo-radiation was evaluated in vitro in GSCs, and in vivo using zebrafish and mouse intracranial glioma xenograft models. The effects of HSP90 inhibition on the transcriptome and cytoplasmic proteins was assessed in GSCs and in ex vivo organotypic human glioma slice cultures.

RESULTS

Treatment with onalespib depleted CHK1 and RAD51, two key proteins of the HR pathway, and attenuated HR repair, sensitizing GSCs to the combination of radiation and temozolomide (TMZ). HSP90 inhibition reprogrammed the transcriptome of GSCs and broadly altered expression of cytoplasmic proteins including known and novel client proteins relevant to GSCs. The combination of onalespib with radiation and TMZ extended survival in a zebra fish and a mouse xenograft model of GBM compared to the standard of care (radiation and TMZ) or onalespib with radiation.

CONCLUSIONS

The results of this study demonstrate that targeting HR by HSP90 inhibition sensitizes GSCs to radiation and chemotherapy and extends survival in zebrafish and mouse intracranial models of GBM. These results provide a preclinical rationale for assessment of HSP90 inhibitors in combination with chemoradiation in GBM patients.

Long term outcomes following surgery for pineal region tumors

PURPOSE

Pineal region tumors are surgically demanding tumors to resect. Long term neuro-oncologic outcomes following surgical excision of tumors from this region have been underreported. We sought to define the long term outcomes of patients undergoing resection of pineal region tumors.

METHODS

A retrospective analysis of a prospectively maintained database was performed on patients who underwent intended surgical excision of pineal region tumors. Overall survival (OS) and progression free survival (PFS) were the primary endpoints of this study. Factors associated with OS, PFS and the degree of resection were analyzed, along with 30-day complication rates and dependence on CSF diversion.

RESULTS

Sixty-eight patients with a mean age of 30.9 ± 15.3 years were analyzed. The median clinical and radiographic follow-up was 95.7 and 48.2 months, respectively. The supracerebellar infratentorial and the occipital transtentorial corridors were utilized in the majority of cases (80.9%). The gross total resection (GTR) rate was 52.9% (n=36). The 5-year OS and PFS rates were 70.2% and 58.5%, respectively. Achieving GTR was associated with improved OS (HR 0.39, p = 0.03) and PFS (HR 0.4, p = 0.006). The 30-day mortality rate was 5.9%. The need for CSF diversion was high with 77.9% of patients requiring a shunt or ETV by last follow-up.

CONCLUSIONS

This is the first modern surgical series providing long term follow-up for patients undergoing surgical resection of pineal region tumors. Obtaining a GTR of these challenging tumors is beneficial with regards to PFS/OS. Higher grade tumors have diminished PFS/OS and are treated with adjuvant chemotherapy and/or radiotherapy.

Perfusion-guided endovascular super-selective intra-arterial infusion for treatment of malignant brain tumors

BACKGROUND

Survival for glioblastoma remains very poor despite decades of research, with a 5-year survival of only 5%. The technological improvements that have revolutionized treatment of ischemic stroke and brain aneurysms have great potential in providing more precise and selective delivery of cancer therapeutic agents to brain tumors.

METHODS

We describe for the first time the use of perfusion guidance to enhance the precision of endovascular super-selective intra-arterial (ESIA) infusions of mesenchymal stem cells loaded with Delta-24 (MSC-D24) in the treatment of glioblastoma (NCT03896568).

RESULTS

MRI imaging, which best defines the location of the tumor, is co-registered and fused with the patient's position using cone beam CT, resulting in optimal vessel selection and confirmation of targeted delivery through volumetric perfusion imaging.

CONCLUSIONS

This technique of perfusion guided-ESIA injections (PG-ESIA) enhances our ability to perform targeted super-selective delivery of therapeutic agents for brain tumors.

Intrinsic Interferon Signaling Regulates the Cell Death and Mesenchymal Phenotype of Glioblastoma Stem Cells

Simple Summary

Interferon signaling is mostly studied in the context of immune cells. However, its role in glioma cancer cells is unclear. This study aimed to investigate the role of cancer-cell-intrinsic IFN signaling in tumorigenesis in glioblastoma (GBM). We found that GSCs and GBM tumors exhibited differential cell-intrinsic type I and type II IFN signaling, and the high IFN/STAT1 signaling was associated with mesenchymal phenotype and poor survival in glioma patients. IFN-β exposure induced cell death in GSCs with intrinsically high IFN/STAT1 signaling, and this effect was abolished by inhibition of IFN/STAT1 signaling. A subset of GBM patients with high IFN/STAT1 may benefit from the IFN-β therapy.

Abstract

Interferon (IFN) signaling contributes to stemness, cell proliferation, cell death, and cytokine signaling in cancer and immune cells; however, the role of IFN signaling in glioblastoma (GBM) and GBM stem-like cells (GSCs) is unclear. Here, we investigated the role of cancer-cell-intrinsic IFN signaling in tumorigenesis in GBM. We report here that GSCs and GBM tumors exhibited differential cell-intrinsic type I and type II IFN signaling, and high IFN/STAT1 signaling was associated with mesenchymal phenotype and poor survival outcomes. In addition, chronic inhibition of IFN/STAT1 signaling decreased cell proliferation and mesenchymal signatures in GSCs with intrinsically high IFN/STAT1 signaling. IFN-β exposure induced apoptosis in GSCs with intrinsically high IFN/STAT1 signaling, and this effect was abolished by the pharmacological inhibitor ruxolitinib and STAT1 knockdown. We provide evidence for targeting IFN signaling in a specific sub-group of GBM patients. IFN-β may be a promising candidate for adjuvant GBM therapy.

NMR Spectroscopy-Based Metabolomics of Platelets to Analyze Brain Tumors

“Tumor-educated platelets” have recently generated substantial interest for the diagnosis of cancer. We hypothesized that tumor educated platelets from patients with brain tumors will reflect altered metabolism compared to platelets from healthy volunteers. Here, in a pilot study, we have employed nuclear magnetic resonance (NMR) spectroscopy in platelets from brain tumor patients to demonstrate altered metabolism compared to the platelets obtained from healthy volunteers.

Measuring the Metabolic Evolution of Glioblastoma throughout Tumor Development, Regression, and Recurrence with Hyperpolarized Magnetic Resonance

Rapid diagnosis and therapeutic monitoring of aggressive diseases such as glioblastoma can improve patient survival by providing physicians the time to optimally deliver treatment. This research tested whether metabolic imaging with hyperpolarized MRI could detect changes in tumor progression faster than conventional anatomic MRI in patient-derived glioblastoma murine models. To capture the dynamic nature of cancer metabolism, hyperpolarized MRI, NMR spectroscopy, and immunohistochemistry were performed at several time-points during tumor development, regression, and recurrence. Hyperpolarized MRI detected significant changes of metabolism throughout tumor progression whereas conventional MRI was less sensitive. This was accompanied by aberrations in amino acid and phospholipid lipid metabolism and MCT1 expression. Hyperpolarized MRI can help address clinical challenges such as identifying malignant disease prior to aggressive growth, differentiating pseudoprogression from true progression, and predicting relapse. The individual evolution of these metabolic assays as well as their correlations with one another provides context for further academic research.

Characterization of patient-derived bone marrow human mesenchymal stem cells as oncolytic virus carriers for the treatment of glioblastoma

OBJECTIVE

Delta-24-RGD is an oncolytic adenovirus that is capable of replicating in and killing human glioma cells. Although intratumoral delivery of Delta-24-RGD can be effective, systemic delivery would improve its clinical application. Bone marrow-derived human mesenchymal stem cells (BM-hMSCs) obtained from healthy donors have been investigated as virus carriers. However, it is unclear whether BM-hMSCs can be derived from glioma patients previously treated with marrow-toxic chemotherapy or whether such BM-hMSCs can deliver oncolytic viruses effectively. Herein, the authors undertook a prospective clinical trial to determine the feasibility of obtaining BM-hMSCs from patients with recurrent malignant glioma who were previously exposed to marrow-toxic chemotherapy.

METHODS

The authors enrolled 5 consecutive patients who had been treated with radiation therapy and chemotherapy. BM aspirates were obtained from the iliac crest and were cultured to obtain BM-hMSCs.

RESULTS

The patient-derived BM-hMSCs (PD-BM-hMSCs) had a morphology similar to that of healthy donor-derived BM-hMSCs (HD-BM-hMSCs). Flow cytometry revealed that all 5 cell lines expressed canonical MSC surface markers. Importantly, these cultures could be made to differentiate into osteocytes, adipocytes, and chondrocytes. In all cases, the PD-BM-hMSCs homed to intracranial glioma xenografts in mice after intracarotid delivery as effectively as HD-BM-hMSCs. The PD-BM-hMSCs loaded with Delta-24-RGD (PD-BM-MSC-D24) effectively eradicated human gliomas in vitro. In in vivo studies, intravascular administration of PD-BM-MSC-D24 increased the survival of mice harboring U87MG gliomas.

CONCLUSIONS

The authors conclude that BM-hMSCs can be acquired from patients previously treated with marrow-toxic chemotherapy and that these PD-BM-hMSCs are effective carriers for oncolytic viruses.

Targeting the αv integrin/TGF-β axis improves natural killer cell function against glioblastoma stem cells

Glioblastoma multiforme (GBM), the most aggressive brain cancer, recurs because glioblastoma stem cells (GSCs) are resistant to all standard therapies. We showed that GSCs, but not normal astrocytes, are sensitive to lysis by healthy allogeneic natural killer (NK) cells in vitro. Mass cytometry and single-cell RNA sequencing of primary tumor samples revealed that GBM tumor-infiltrating NK cells acquired an altered phenotype associated with impaired lytic function relative to matched peripheral blood NK cells from patients with GBM or healthy donors. We attributed this immune evasion tactic to direct cell-to-cell contact between GSCs and NK cells via αv integrin-mediated TGF-β activation. Treatment of GSC-engrafted mice with allogeneic NK cells in combination with inhibitors of integrin or TGF-β signaling or with TGFBR2 gene-edited allogeneic NK cells prevented GSC-induced NK cell dysfunction and tumor growth. These findings reveal an important mechanism of NK cell immune evasion by GSCs and suggest the αv integrin/TGF-β axis as a potentially useful therapeutic target in GBM.

Inhibition of nicotinamide phosphoribosyltransferase, the rate-limiting enzyme of the nicotinamide adenine dinucleotide salvage pathway, to target glioma heterogeneity through mitochondrial oxidative stress

BACKGROUND

Tumor-specific metabolic processes essential for cell survival are promising targets to potentially circumvent intratumoral heterogeneity, a major resistance factor in gliomas. Tumor cells preferentially using nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the salvage pathway for synthesis of NAD, a critical cofactor for diverse biological processes including cellular redox reactions, energy metabolism and biosynthesis. NAMPT is overexpressed in most malignancies, including gliomas, and can serve as a tumor-specific target.

METHODS

Effects of pharmacological inhibition of NAMPT on cellular oxygen consumption rate, extracellular acidification, mitochondrial respiration, cell proliferation, invasion and survival were assessed through in vitro and ex vivo studies on genetically heterogeneous glioma cell lines, glioma stem-like cells (GSCs) and mouse and human ex vivo organotypic glioma slice culture models.

RESULTS

Pharmacological inhibition of the NAD salvage biosynthesis pathway using a highly specific inhibitor, KPT-9274, resulted in reduction of NAD levels and related downstream metabolites, inhibited proliferation, and induced apoptosis in vitro in cell lines and ex vivo in human glioma tissue. These effects were mediated by mitochondrial dysfunction, DNA damage and increased oxidative stress leading to apoptosis in GSCs independent of genotype, IDH status or MGMT promoter methylation status. Conversely, NAMPT inhibition had minimal in vitro effects on normal human astrocytes (NHA) and no apparent in vivo toxicity in non-tumor-bearing mice.

CONCLUSIONS

Pharmacological NAMPT inhibition by KPT9274 potently targeted genetically heterogeneous gliomas by activating mitochondrial dysfunction. Our preclinical results provide a rationale for targeting the NAMPT-dependent alternative NAD biosynthesis pathway as a novel clinical strategy against gliomas.

OTME-23. Single-cell transcriptomic and epigenomic immune landscape of isocitrate dehydrogenase stratified human gliomas

The brain tumor immune microenvironment (TIME) continuously evolves during glioma progression, but a comprehensive characterization of the glioma-centric immune cell repertoire beyond a priori cell states is uncharted. In this study, we performed single-cell RNA-sequencing (scRNA-seq) and single cell- Assay for Transposase-Accessible Chromatin using sequencing (sc-ATAC-seq) on ~100,000 tumor-associated immune cells from seventeen isocitrate dehydrogenase (IDH) mutation classified primary and recurrent human gliomas and non-glioma brains (NGBs). Our analyses revealed sixty-two transcriptionally distinct myeloid and lymphoid cell states within and across glioma subtypes and we noted microglial attrition with increasing disease severity concomitant with invading monocyte-derived cells and lymphocytes. Specifically, certain microglial and monocyte-derived subpopulations were associated with antigen presentation gene modules, akin to cross-presenting dendritic cells (DCs). We identified cytotoxic T cells with poly-functional cytolytic states mostly in recurrent IDH-wt gliomas. Furthermore, ligand-receptor interactome analyses showed a preponderance of antigen presentation and phagocytosis over the checkpoint axis in IDH-wt compared to IDH-mut gliomas.

Additionally, our sc-ATAC-seq analyses revealed differences in regulatory networks in NGBs, IDH-mut and IDH-wt glioma associated immune cells. In particular, we noted abundant usage of inflammatory transcription factors (TFs) as exemplified by Nuclear factor kappa B and Activator Protein-1 TF family in IDH-wt microglia when compared with microglia from IDH-mut and NGBs. Unique features such as amplification of 11- Zinc Finger Protein accessibility were restricted to monocyte derived cells and were not observed in microglia. Finally, sc-ATAC-seq profiles of CD8⁺ exhausted T cells from IDH-wt showed strong enhancer accessibility on Cytotoxic T-lymphocyte-associated protein 4, Layilin and Hepatitis A Virus Cellular Receptor 2 but no enrichment on PDCD1 (gene encoding Programmed cell death protein 1) was seen. In summary, our study provides unprecedented granular detail of transcriptionally defined glioma- specific immune contexture that can be exploited for immunotherapy applications.

This study in K.B. laboratory was supported by the generous philanthropic contributions to The University of Texas (UT) MD Anderson Cancer Center (MDACC) Moon Shots Program™, Marnie Rose Foundation, NIH grants: R21 CA222992 and R01CA225963. This study was partly supported by the UT MDACC start-up research fund to L.W. and CPRIT Single Core grant RP180684 to N. E. N.

Language supplementary motor area syndrome correlated with dynamic changes in perioperative task-based functional MRI activations: case report

Supplementary motor area (SMA) syndrome is well known; however, the mechanism underlying recovery from language SMA syndrome is unclear. Herein the authors report the case of a right-handed woman with speech aphasia following resection of an oligodendroglioma located in the anterior aspect of the left superior frontal gyrus. The patient exhibited language SMA syndrome, and functional MRI (fMRI) findings 12 days postoperatively demonstrated a complete shift of blood oxygen level–dependent (BOLD) activation to the contralateral right language SMA/pre-SMA as well as coequal activation and an increased volume of activation in the left Broca’s area and the right Broca’s homolog. The authors provide, to the best of their knowledge, the first description of dynamic changes in task-based hemispheric language BOLD fMRI activations across the preoperative, immediate postoperative, and more distant postoperative settings associated with the development and subsequent complete resolution of the clinical language SMA syndrome.

EPCT-04. RESULTS OF A PHASE 1 STUDY OF THE ONCOLYTIC ADENOVIRUS DNX-2401 WITH RADIOTHERAPY FOR NEWLY DIAGNOSED DIFFUSE INTRINSIC PONTINE GLIOMA (DIPG)

Background

A Phase 1, single center study is ongoing to evaluate the conditionally replicative oncolytic adenovirus, DNX-2401 (tasadenoturev), followed by radiotherapy (RT) in pediatric patients with newly diagnosed diffuse intrinsic pontine glioma (DIPG).

Methods

Patients 1–18 years with newly diagnosed DIPG with no prior treatment, Lansky/Karnofsky performance score ≥ 70, and adequate organ function were enrolled. A tumor biopsy was performed followed by a single intratumoral injection of 1e10-5e10 virus particles (vp) DNX-2401. Conventional radiotherapy was initiated within 1 month of DNX-2401 administration.

Results

Enrolled subjects (n=12) had a median age of 9 (range 3–18) and performance scores of 90–100 (n=4; 33%) or 70–80 (n=8; 67%). As part of a dose escalation design, subjects were treated with 1e10 vp (n=4) or 5e10 vp DNX-2401 (n=8), which was then followed by standard RT in 11 of 12 subjects (92%). No dose-limiting toxicities were observed and the treatment regimen was well-tolerated. Adverse events (AEs) have been primarily mild to moderate and consistent with underlying disease. The most commonly reported AEs (≥ 5 subjects), regardless of study drug relationship, include headache, asthenia, vomiting, anemia, leukocytosis, and fever. Two SAEs have been reported including grade 3 lymphopenia and grade 3 abdominal pain. Tumor reductions have been observed and efficacy evaluations are ongoing. As of 09Dec2020, 12-month survival (OS-12) was 71% and 4 of 12 patients had survived > 20 months. Four subjects continue to be followed for survival. Correlative analysis of tumor biopsy and peripheral samples is ongoing.

Conclusions

DNX-2401 followed by RT can be safely administered to pediatric subjects with newly diagnosed DIPG; clinical activity and preliminary survival are encouraging.