Immunomodulation for glioblastoma

The ClearPoint Array Frame: An MRI Compatible System that Supports Non-craniotomy, Multi-trajectory (NCMT) Stereotactic Procedures

BACKGROUND

With continued evolution in stereotactic techniques and an expanding armamentarium of surgical therapeutic options, non-craniotomy stereotactic procedures in neuro-oncology are becoming increasingly complex, often requiring multi-trajectory approaches. Here we demonstrate that the ClearPoint SmartFrame Array (Solana Beach, California, USA), a second-generation magnetic resonance imaging-compatible stereotactic frame, supports such non-craniotomy, multi-trajectory (NCMT) stereotactic procedures.

METHODS

We previously published case reports demonstrating the feasibility of NCMT through the ClearPoint SmartFrame Array. Here we prospectively followed the next 10 consecutive patients who underwent such multi-trajectory procedures to further establish procedural safety and clinical utility.

RESULTS

Ten patients underwent complex, multi-trajectory stereotactic procedures, including combinations of needle biopsy ± cyst drainage and laser interstitial thermal therapy targeting geographically distinct regions of neoplastic lesions under the same anesthetic event. The median maximal radial error of stereotaxis was 1.0 mm. In all cases, definitive diagnosis was achieved, and >90% of the intended targets were ablated. The average stereotaxis time for the multi-trajectory procedure was 119 ± 22.2 minutes, comparing favorably to our previously published results of single-trajectory procedures (80 ± 9.59 minutes, P = 0.125). There were no procedural complications. Post-procedure, the neurologic condition of 1 patient improved, while the remaining 9 patients remained stable. All patients were discharged home, with a median hospital stay of 1 day (range: 1-12 days). With a median follow-up of 376 days (range: 155-1438 days), there were no 30-day readmissions or wound complications.

CONCLUSIONS

Geographically distinct regions of brain cancer can be safely and accurately accessed through the ClearPoint Array frame in NCMT stereotactic procedures.

Highly Active Myeloid Therapy for Cancer

Tumor-associated macrophages (TAM) interact with cancer and stromal cells and are integral to sustaining many cancer-promoting features. Therapeutic manipulation of TAM could therefore improve clinical outcomes and synergize with immunotherapy and other cancer therapies. While different nanocarriers have been used to target TAM, a knowledge gap exists on which TAM pathways to target and what payloads to deliver for optimal antitumor effects. We hypothesized that a multipart combination involving the Janus tyrosine kinase (JAK), noncanonical nuclear factor kappa light chain enhancer of activated B cells (NF-κB), and toll-like receptor (TLR) pathways could lead to a highly active myeloid therapy (HAMT). Thus, we devised a screen to determine drug combinations that yield maximum IL-12 production from myeloid cells to treat the otherwise highly immunosuppressive myeloid environments in tumors. Here we show the extraordinary efficacy of a triple small-molecule combination in a TAM-targeted nanoparticle for eradicating murine tumors, jumpstarting a highly efficient antitumor response by adopting a distinctive antitumor TAM phenotype and synergizing with other immunotherapies. The HAMT therapy represents a recently developed approach in immunotherapy and leads to durable responses in murine cancer models.

Kavain ablates the radio-resistance of IDH-wildtype glioblastoma by targeting LITAF/NF-κB pathway

BACKGROUND

Glioblastoma multiforma (GBM) is the most malignant intrinsic tumor of the central nervous system (CNS), with high morbidity of 3.19/100,000 per year and a poor 5-year survival rate (< 5%) worldwide. Numerous studies have indicated that GBM shows remarkable radioresistance and aggressive recurrence. However, the mechanisms to endow GBM cells with radioresistance are complex and unclear.

METHODS

Cell growth curve and colony formation assays were used to analyze the radioresistance of GBM. Immunoprecipitation and immunoblotting experiments were carried out to analyze protein expression and interaction.

RESULTS

In the present study, we found that LITAF, lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α factor, is up-regulated both in mRNA and protein in GBM tumors. Meanwhile, we observed that high LITAF expression contributes to radioresistance of GBM cell lines (including U87, U251, DK, and AM38 cells), indicated by knockout or knockdown of LITAF in cells sensitizing them to radiation treatment both in vitro and in vivo. Furthermore, we demonstrated that kavain, an active constituent of Piper methysticum Forst., effectively ablates GSC-like cells' (such as CD133 + U87, U251, DK, and AM38 populations) radioresistance in a LITAF-dependent manner.

CONCLUSION

In mechanism, our results indicated that 1) the elevation of LITAF in GBM cells activates the NF-κB pathway to promote mesenchymal transition, and 2) kavain disturbs STAT6B/LITAF protein interaction and then expels LITAF from the nucleus. Therefore, we consider that kavain may be a potential candidate to develop an irradiation therapy adjuvant for GBM.

The Presence and Potential Role of ALDH1A2 in the Glioblastoma Microenvironment

Glioblastoma (GBM) is the most aggressive malignant glioma. Therapeutic targeting of GBM is made more difficult due to its heterogeneity, resistance to treatment, and diffuse infiltration into the brain parenchyma. Better understanding of the tumor microenvironment should aid in finding more effective management of GBM. GBM-associated macrophages (GAM) comprise up to 30% of the GBM microenvironment. Therefore, exploration of GAM activity/function and their specific markers are important for developing new therapeutic agents. In this study, we identified and evaluated the expression of ALDH1A2 in the GBM microenvironment, and especially in M2 GAM, though it is also expressed in reactive astrocytes and multinucleated tumor cells. We demonstrated that M2 GAM highly express ALDH1A2 when compared to other ALDH1 family proteins. Additionally, GBM samples showed higher expression of ALDH1A2 when compared to low-grade gliomas (LGG), and this expression was increased upon tumor recurrence both at the gene and protein levels. We demonstrated that the enzymatic product of ALDH1A2, retinoic acid (RA), modulated the expression and activity of MMP-2 and MMP-9 in macrophages, but not in GBM tumor cells. Thus, the expression of ALDH1A2 may promote the progressive phenotype of GBM.

Exploiting Radiation Therapy to Restore Immune Reactivity of Glioblastoma

Glioblastoma (GBM) is among the most aggressive of brain tumors and confers a dismal prognosis despite advances in surgical technique, radiation delivery methods, chemotherapy, and tumor-treating fields. While immunotherapy (IT) has improved the care of several adult cancers with previously dismal prognoses, monotherapy with IT in GBM has shown minimal response in first recurrence. Recent discoveries in lymphatics and evaluation of blood brain barrier offer insight to improve the use of ITs and determine the best combinations of therapies, including radiation. We highlight important features of the tumor immune microenvironment in GBM and potential for combining radiation and immunotherapy to improve prognosis in this devastating disease.

Profiling of inhibitory immune checkpoints in glioblastoma: Potential pathogenetic players

Glioblastoma (GBM) represents the most frequent glial tumor, with almost 3 new cases per 100,000 people per year. Despite treatment, the prognosis for GBM patients remains extremely poor, with a median survival of 14.6 months, and a 5-year survival less than 5%. It is generally believed that GBM creates a highly immunosuppressive microenvironment, sustained by the expression of immune-regulatory factors, including inhibitory immune checkpoints, on both infiltrating cells and tumor cells. However, the trials assessing the efficacy of current immune checkpoint inhibitors in GBM are still disappointing. In the present study, the expression levels of several inhibitory immune checkpoints in GBM (CD276, VTCN1, CD47, PVR, TNFRSF14, CD200, LGALS9, NECTIN2 and CD48) were characterized in order to evaluate their potential as prognostic and eventually, therapeutic targets. Among the investigated immune checkpoints, TNFRSF14 and NECTIN2 were identified as the most promising targets in GBM. In particular, a higher TNFRSF14 expression was associated with worse overall survival and disease-free survival, and with a lower Th1 response.

Personalized neoantigen vaccines: a glimmer of hope for glioblastoma

INTRODUCTION

Glioblastoma multiforme (GBM) is the most prevalent primary brain tumor. In spite of the rigorous multimodal treatment involving surgery and radiochemotherapy, GBM has a dismal prognosis and rapid relapsing potential. Hence, search for novel therapeutic agents still continues. Neoantigens are the tumor-specific antigens which arise due to somatic mutations in the tumor genome. In recent years, personalized vaccine approach targeting neoantigens has been explored widely in cancer immunotherapy and several efforts have also been made to revolutionize the immunotherapy of cold tumors such as GBM using neoantigen targeted vaccines.

AREAS COVERED

In this review, we discuss the clinical application of personalized neoantigen targeted vaccine strategy in GBM immunotherapy. While discussing this strategy, we brief about the current challenges faced in GBM treatment by the novel immunotherapeutics.

EXPERT OPINION

To date, very few vaccines developed for GBM have reached till phase III clinical development. Early-phase clinical trials of GBM neoantigen vaccines have shown promising clinical outcomes and therefore, its rapid clinical development is warranted. Advent of newer and faster techniques such as next-generation sequencing will drive the faster clinical development of multiplex neoantigen vaccines and hence, increase in the clinical trials is expected.

Tumor Vessel Normalization, Immunostimulatory Reprogramming, and Improved Survival in Glioblastoma with Combined Inhibition of PD-1, Angiopoietin-2, and VEGF

Glioblastoma (GBM) is a non-T-cell-inflamed cancer characterized by an immunosuppressive microenvironment that impedes dendritic cell maturation and T-cell cytotoxicity. Proangiogenic cytokines such as VEGF and angiopoietin-2 (Ang-2) have high expression in glioblastoma in a cell-specific manner and not only drive tumor angiogenesis and vascular permeability but also negatively regulate T-lymphocyte and innate immune cell responses. Consequently, the alleviation of immunosuppression might be a prerequisite for successful immune checkpoint therapy in GBM. We here combined antiangiogenic and immune checkpoint therapy and demonstrated improved therapeutic efficacy in syngeneic, orthotopic GBM models. We observed that blockade of VEGF, Ang-2, and programmed cell death protein-1 (PD-1) significantly extended survival compared with vascular targeting alone. In the GBM microenvironment, triple therapy increased the numbers of CTLs, which inversely correlated with myeloid-derived suppressor cells and regulatory T cells. Transcriptome analysis of GBM microvessels indicated a global vascular normalization that was highest after triple therapy. Our results propose a rationale to overcome tumor immunosuppression and the current limitations of VEGF monotherapy by integrating the synergistic effects of VEGF/Ang-2 and PD-1 blockade to reinforce antitumor immunity through a normalized vasculature.

Regulatable interleukin-12 gene therapy in patients with recurrent high-grade glioma: Results of a phase 1 trial

Human interleukin-12 (hIL-12) is a cytokine with anticancer activity, but its systemic application is limited by toxic inflammatory responses. We assessed the safety and biological effects of an hIL-12 gene, transcriptionally regulated by an oral activator. A multicenter phase 1 dose-escalation trial (NCT02026271) treated 31 patients undergoing resection of recurrent high-grade glioma. Resection cavity walls were injected (day 0) with a fixed dose of the hIL-12 vector (Ad-RTS-hIL-12). The oral activator for hIL-12, veledimex (VDX), was administered preoperatively (assaying blood-brain barrier penetration) and postoperatively (measuring hIL-12 transcriptional regulation). Cohorts received 10 to 40 mg of VDX before and after Ad-RTS-hIL-12. Dose-related increases in VDX, IL-12, and interferon-γ (IFN-γ) were observed in peripheral blood, with about 40% VDX tumor penetration. Frequency and severity of adverse events, including cytokine release syndrome, correlated with VDX dose, reversing promptly upon discontinuation. VDX (20 mg) had superior drug compliance and 12.7 months median overall survival (mOS) at mean follow-up of 13.1 months. Concurrent corticosteroids negatively affected survival: In patients cumulatively receiving >20 mg versus ≤20 mg of dexamethasone (days 0 to 14), mOS was 6.4 and 16.7 months, respectively, in all patients and 6.4 and 17.8 months, respectively, in the 20-mg VDX cohort. Re-resection in five of five patients with suspected recurrence after Ad-RTS-hIL-12 revealed mostly pseudoprogression with increased tumor-infiltrating lymphocytes producing IFN-γ and programmed cell death protein 1 (PD-1). These inflammatory infiltrates support an immunological antitumor effect of hIL-12. This phase 1 trial showed acceptable tolerability of regulated hIL-12 with encouraging preliminary results.

Histone deacetylase enzymes and selective histone deacetylase inhibitors for antitumor effects and enhancement of antitumor immunity in glioblastoma

Glioblastoma multiforme (GBM), which is the most common primary central nervous system malignancy in adults, has long presented a formidable challenge to researchers and clinicians alike. Dismal 5-year survival rates of the patients with these tumors and the ability of the recurrent tumors to evade primary treatment strategies have prompted a need for alternative therapies in the treatment of GBM. Histone deacetylase (HDAC) inhibitors are currently a potential epigenetic therapy modality under investigation for use in GBM with mixed results. While these agents show promise through a variety of proposed mechanisms in the pre-clinical realm, only several of these agents have shown this same promise when translated into the clinical arena, either as monotherapy or for use in combination regimens. This review will examine the current state of use of HDAC inhibitors in GBM, the mechanistic rationale for use of HDAC inhibitors in GBM, and then examine an exciting new mechanistic revelation of certain HDAC inhibitors that promote antitumor immunity in GBM. The details of this antitumor immunity will be discussed with an emphasis on application of this antitumor immunity towards developing alternative therapies for treatment of GBM. The final section of this article will provide an overview of the current state of immunotherapy targeted specifically to GBM.

Pathogenic role for macrophage migration inhibitory factor in glioblastoma and its targeting with specific inhibitors as novel tailored therapeutic approach

Macrophage Migration Inhibitory Factor (MIF) is a pro-inflammatory cytokine expressed by a variety of cell types. Although MIF has been primarily studied for its role in the pathogenesis of autoimmune diseases, it has also been shown to promote tumorigenesis and it is over expressed in various malignant tumors. MIF is able to induce angiogenesis, cell cycle progression, and to block apoptosis. As tailored therapeutic approaches for the inhibition of endogenous MIF are being developed, it is important to evaluate the role of MIF in individual neoplastic conditions that may benefit from specific MIF inhibitors. Along with this line, in this paper, we have reviewed the evidence of the involvement of MIF in the etiopathogenesis and progression of glioblastoma and the preclinical data suggesting the possible use of specific MIF inhibition as a potential novel therapeutic strategy for brain tumors.

Developmentally regulated signaling pathways in glioma invasion

Malignant gliomas are the most common, infiltrative, and lethal primary brain tumors affecting the adult population. The grim prognosis for this disease is due to a combination of the presence of highly invasive tumor cells that escape surgical resection and the presence of a population of therapy-resistant cancer stem cells found within these tumors. Several studies suggest that glioma cells have cleverly hijacked the normal developmental program of neural progenitor cells, including their transcriptional programs, to enhance gliomagenesis. In this review, we summarize the role of developmentally regulated signaling pathways that have been found to facilitate glioma growth and invasion. Furthermore, we discuss how the microenvironment and treatment-induced perturbations of these highly interconnected signaling networks can trigger a shift in cellular phenotype and tumor subtype.

Contemporary management of high-grade gliomas

High-grade gliomas, including glioblastoma, are the most common malignant brain tumors in adults. Despite intensive efforts to develop new therapies for these diseases, treatment options remain limited and prognosis is poor. Recently, there have been important advances in our understanding of the molecular basis of glioma, leading to refinements in our diagnostic and management approach. There is new evidence to guide the treatment of elderly patients. A multitude of new agents have been investigated, including targeted therapies, immunotherapeutics and tumor-treating fields. This review summarizes the key findings from this research, and presents a perspective on future opportunities to advance the field.

Neutrophils in Gliomas

Neutrophils are the most abundant white blood cells and are the first recruited to inflammatory sites. Neutrophils are an important component of the tumor stroma and can exert both anti-tumoral and pro-tumoral activities, depending on their maturation and activation state. In human gliomas, the number of circulating and infiltrating neutrophils correlates with the severity of the disease, indicating a prognostic and possible pro-tumoral role for these leukocytes. In glioma preclinical models, neutrophils promote tumor growth and orchestrate the resistance to anti-angiogenic therapies. Nevertheless, recent data indicate that neutrophils can be activated to directly kill tumor cells or to orchestrate the anti-tumoral response. Here, we review current knowledge about the role of neutrophils in glioma and their possible involvement in new strategies to improve current cancer therapies.