Successful treatment of melanoma brain metastases with adoptive cell therapy

Current approaches in glioblastoma multiforme immunotherapy

Glioblastoma multiform (GBM) is the most prevalent CNS (central nervous system) tumor in adults, with an average survival length shorter than 2 years and rare metastasis to organs other than CNS. Despite extensive attempts at surgical resecting, the inherently permeable nature of this disease has rendered relapse nearly unavoidable. Thus, immunotherapy is a feasible alternative, as stimulated immune cells can enter into the remote and inaccessible tumor cells. Immunotherapy has revolutionized patient upshots in various malignancies and might introduce different effective ways for GBM patients. Currently, researchers are exploring various immunotherapeutic strategies in patients with GBM to target both the innate and acquired immune responses. These approaches include reprogrammed tumor-associated macrophages, the use of specific antibodies to inhibit tumor progression and metastasis, modifying tumor-associated macrophages with antibodies, vaccines that utilize tumor-specific dendritic cells to activate anti-tumor T cells, immune checkpoint inhibitors, and enhanced T cells that function against tumor cells. Despite these findings, there is still room for improving the response faults of the many currently tested immunotherapies. This study aims to review the currently used immunotherapy approaches with their molecular mechanisms and clinical application in GBM.

Biomarkers for response to TIL therapy: a comprehensive review

Adoptive cell therapy with tumor-infiltrating lymphocytes (TIL) has demonstrated durable clinical responses in patients with metastatic melanoma, substantiated by recent positive results of the first phase III trial on TIL therapy. Being a demanding and logistically complex treatment, extensive preclinical and clinical effort is required to optimize patient selection by identifying predictive biomarkers of response. This review aims to comprehensively summarize the current evidence regarding the potential impact of tumor-related factors (such as mutational burden, neoantigen load, immune infiltration, status of oncogenic driver genes, and epigenetic modifications), patient characteristics (including disease burden and location, baseline cytokines and lactate dehydrogenase serum levels, human leucocyte antigen haplotype, or prior exposure to immune checkpoint inhibitors and other anticancer therapies), phenotypic features of the transferred T cells (mainly the total cell count, CD8:CD4 ratio, ex vivo culture time, expression of exhaustion markers, costimulatory signals, antitumor reactivity, and scope of target tumor-associated antigens), and other treatment-related factors (such as lymphodepleting chemotherapy and postinfusion administration of interleukin-2).

Expert consensus guidelines on management and best practices for tumor-infiltrating lymphocyte cell therapy

Adoptive cell therapy with autologous, ex vivo-expanded, tumor-infiltrating lymphocytes (TILs) is being investigated for treatment of solid tumors and has shown robust responses in clinical trials. Based on the encouraging efficacy, tolerable safety profile, and advancements in a central manufacturing process, lifileucel is now the first US Food and Drug Administration (FDA)-approved TIL cell therapy product. To this end, treatment management and delivery practice guidance is needed to ensure successful integration of this modality into clinical care. This review includes clinical and toxicity management guidelines pertaining to the TIL cell therapy regimen prepared by the TIL Working Group, composed of internationally recognized hematologists and oncologists with expertize in TIL cell therapy, and relates to patient care and operational aspects. Expert consensus recommendations for patient management, including patient eligibility, screening tests, and clinical and toxicity management with TIL cell therapy, including tumor tissue procurement surgery, non-myeloablative lymphodepletion, TIL infusion, and IL-2 administration, are discussed in the context of potential standard of care TIL use. These recommendations provide practical guidelines for optimal clinical management during administration of the TIL cell therapy regimen, and recognition of subsequent management of toxicities. These guidelines are focused on multidisciplinary teams of physicians, nurses, and stakeholders involved in the care of these patients.

Mechanisms of Melanoma Progression and Treatment Resistance: Role of Cancer Stem-like Cells

Melanoma is the third most common type of skin cancer, characterized by its heterogeneity and propensity to metastasize to distant organs. Melanoma is a heterogeneous tumor, composed of genetically divergent subpopulations, including a small fraction of melanoma-initiating cancer stem-like cells (CSCs) and many non-cancer stem cells (non-CSCs). CSCs are characterized by their unique surface proteins associated with aberrant signaling pathways with a causal or consequential relationship with tumor progression, drug resistance, and recurrence. Melanomas also harbor significant alterations in functional genes (BRAF, CDKN2A, NRAS, TP53, and NF1). Of these, the most common are the BRAF and NRAS oncogenes, with 50% of melanomas demonstrating the BRAF mutation (BRAFV600E). While the successful targeting of BRAFV600E does improve overall survival, the long-term efficacy of available therapeutic options is limited due to adverse side effects and reduced clinical efficacy. Additionally, drug resistance develops rapidly via mechanisms involving fast feedback re-activation of MAPK signaling pathways. This article updates information relevant to the mechanisms of melanoma progression and resistance and particularly the mechanistic role of CSCs in melanoma progression, drug resistance, and recurrence.

Nanomaterials for brain metastasis

Tumor metastasis is a significant contributor to the mortality of cancer patients. Specifically, current conventional treatments are unable to achieve complete remission of brain metastasis. This is due to the unique pathological environment of brain metastasis, which differs significantly from peripheral metastasis. Brain metastasis is characterized by high tumor mutation rates and a complex microenvironment with immunosuppression. Additionally, the presence of blood-brain barrier (BBB)/blood tumor barrier (BTB) restricts drug leakage into the brain. Therefore, it is crucial to take account of the specific characteristics of brain metastasis when developing new therapeutic strategies. Nanomaterials offer promising opportunities for targeted therapies in treating brain metastasis. They can be tailored and customized based on specific pathological features and incorporate various treatment approaches, which makes them advantageous in advancing therapeutic strategies for brain metastasis. This review provides an overview of current clinical treatment options for patients with brain metastasis. It also explores the roles and changes that different cells within the complex microenvironment play during tumor spread. Furthermore, it highlights the use of nanomaterials in current brain treatment approaches.

Cell-based therapies for glioblastoma: Promising tools against tumor heterogeneity

Glioblastoma (GBM) is a highly aggressive tumor with a devastating impact on quality-of-life and abysmal survivorship. Patients have very limited effective treatment options. The successes of targeted small molecule drugs and immune checkpoint inhibitors seen in various solid tumors have not translated to GBM, despite significant advances in our understanding of its molecular, immune, and microenvironment landscapes. These discoveries, however, have unveiled GBM's incredible heterogeneity and its role in treatment failure and survival. Novel cellular therapy technologies are finding successes in oncology and harbor characteristics that make them uniquely suited to overcome challenges posed by GBM, such as increased resistance to tumor heterogeneity, modularity, localized delivery, and safety. Considering these advantages, we compiled this review article on cellular therapies for GBM, focusing on cellular immunotherapies and stem cell-based therapies, to evaluate their utility. We categorize them based on their specificity, review their preclinical and clinical data, and extract valuable insights to help guide future cellular therapy development.

Type I interferon response in astrocytes promotes brain metastasis by enhancing monocytic myeloid cell recruitment

Cancer metastasis to the brain is a significant clinical problem. Metastasis is the consequence of favorable interactions between invaded cancer cells and the microenvironment. Here, we demonstrate that cancer-activated astrocytes create a sustained low-level activated type I interferon (IFN) microenvironment in brain metastatic lesions. We further confirm that the IFN response in astrocytes facilitates brain metastasis. Mechanistically, IFN signaling in astrocytes activates C-C Motif Chemokine Ligand 2 (CCL2) production, which further increases the recruitment of monocytic myeloid cells. The correlation between CCL2 and monocytic myeloid cells is confirmed in clinical brain metastasis samples. Lastly, genetically or pharmacologically inhibiting C-C Motif Chemokine Receptor 2 (CCR2) reduces brain metastases. Our study clarifies a pro-metastatic effect of type I IFN in the brain even though IFN response has been considered to have anti-tumor effects. Moreover, this work expands our understandings on the interactions between cancer-activated astrocytes and immune cells in brain metastasis.

Lymphodepleting chemotherapy practices and effect on safety and efficacy outcomes in patients with solid tumours undergoing T cell receptor-engineered T cell (TCR-T) Therapy: a systematic review and meta-analysis

BACKGROUND

T cell receptor-engineered T cell (TCR-T) therapy has shown promising efficacy in advanced solid tumours. Lymphodepleting (LD) chemotherapy improves TCR-T cell therapy efficacy but is associated with significant toxicities. Evidence is sparse regarding the optimum LD regimen for TCR-T cell therapy in solid tumours.

METHODS

A systematic review was conducted of interventional, prospective clinical trials describing LD practices prior to TCR-T cell therapy in patients with advanced solid tumours. The objective was to define LD regimens administered prior to TCR-T cell therapy and their effects on specific safety and efficacy outcomes in this patient population.

RESULTS

Searches returned 484 studies, 19 (231 patients) met the eligibility criteria. Cyclophosphamide (cyclo) 60 mg/kg daily (2 days), plus fludarabine (fludara) 25 mg/m2 daily (5 days) was the most common LD regimen (38% of studies). Higher dose LD regimens were associated with increased pooled incidence rates of febrile neutropaenia compared to low dose (0.64, [95% Confidence interval (CI): 0.50-0.78], vs. 0.39 [95% CI: 0.25-0.53], respectively) but were not significantly associated with higher objective responses (odds ratio: 1.05, 95%CI: 0.60-1.82, p = 0.86). A major shortfall in safety data reporting was identified; determination of LD regimen effects on many safety outcomes was not possible.

CONCLUSION

Standard consensus guidelines for the design and reporting of adoptive cell therapy (ACT) studies would facilitate accurate risk-benefit analysis for optimising LD regimens in patients with advanced solid tumours.

IL13Rα2-targeted third-generation CAR-T cells with CD28 transmembrane domain mediate the best anti-glioblastoma efficacy

Chimeric antigen receptor (CAR)-modified T (CAR-T) cell therapy has been proven to be a powerful tool for the treatment of cancer, however, the limits are obvious, especially for solid tumors. Therefore, constantly optimizing the structure of CAR to improve its therapeutic effect is necessary. In this study, we generated three different third-generation CARs targeting IL13Rα2, with the same scFv, but different transmembrane domains (TMDs) from CD4, CD8 or CD28 (IL13-CD4TM-28.BB.ζ, IL13-CD8TM-28.BB.ζ and IL13-CD28TM-28.BB.ζ). CARs were transduced into primary T cells using retroviruses. The anti-GBM efficacy of CAR-T cells was monitored by flow cytometry and real-time cell analysis (RTCA) in vitro and examined in two xenograft mouse models. The differentially expressed genes related to different anti-GBM activity were screened by high throughput RNA sequencing. We observed that T cells transduced with these three CARs have similar anti-tumor activity when co-cultured with U373 cells which expressed higher IL13Rα2 but exhibited different anti-tumor activity when co-cultured with U251 cells that expressed lower IL13Rα2. All the three groups of CAR-T cells can be activated by U373 cells, but only IL13-CD28TM-28.BB.ζ CAR-T cells could be activated and expressed increased IFN-γ after co-culturing with U251 cells. IL13-CD28TM-28.BB.ζ CAR-T cells exhibited the best anti-tumor activity in xenograft mouse models which can infiltrate into the tumors. The superior anti-tumor efficacy of IL13-CD28TM-28.BB.ζ CAR-T cells was partially owing to differentially expressed extracellular assembly, extracellular matrix, cell migration and adhesion-related genes which contribute to the lower activation threshold, increased cell proliferation, and elevated migration capacity.

Effective generation of tumor-infiltrating lymphocyte products from metastatic non-small-cell lung cancer (NSCLC) lesions irrespective of location and previous treatments

Background

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide. Because current treatment regimens show limited success rates, alternative therapeutic approaches are needed. We recently showed that treatment-naïve, stage I/II primary NSCLC tumors contain a high percentage of tumor-reactive T cells, and that these tumor-reactive T cells can be effectively expanded and used for the generation of autologous tumor-infiltrating T cell (TIL) therapy. Whether these promising findings also hold true for metastatic lesions is unknown yet critical for translation into the clinic.

Materials and methods

We studied the lymphocyte composition using flow cytometry from 27 metastatic NSCLC lesions obtained from different locations and from patients with different histories of treatment regimens. We determined the expansion capacity of TILs with the clinically approved protocol, and measured their capacity to produce the key pro-inflammatory cytokines interferon-γ, tumor necrosis factor and interleukin 2 and to express CD137 upon co-culture of expanded TILs with the autologous tumor digest.

Results

The overall number and composition of lymphocyte infiltrates from the various metastatic lesions was by and large comparable to that of early-stage primary NSCLC tumors. We effectively expanded TILs from all metastatic NSCLC lesions to numbers that were compatible with TIL transfusion, irrespective of the location of the metastasis and of the previous treatment. Importantly, 16 of 21 (76%) tested TIL products displayed antitumoral activity, and several contained polyfunctional T cells.

Conclusions

Metastatic NSCLC lesions constitute a viable source for the generation of tumor-reactive TIL products for therapeutic purposes irrespective of their location and the pre-treatment regimens.

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T cells can be efficiently isolated and expanded from late-stage NSCLC lesions.

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TIL products from metastatic NSCLC lesions are polyfunctional.

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Metastatic location or pre-treatment regimen does not affect T cells.

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Adoptive TIL therapy is a therapeutic option for late-stage NSCLC patients.

Clinical feasibility and treatment outcomes with nonselected autologous tumor-infiltrating lymphocyte therapy in patients with advanced cutaneous melanoma

Nonselected autologous tumor-infiltrating lymphocytes (TILs) may provide advantages over other treatments for solid tumors, including checkpoint inhibitor-refractory melanoma. This retrospective analysis reports a single-center experience of nonselected autologous TILs derived from digested tumors for compassionate use treatment of advanced cutaneous melanoma, including after programmed cell death protein 1 (PD-1) inhibition. Patients with histologically confirmed metastatic cutaneous melanoma and no standard-of-care treatment options underwent tumor resection for TIL product manufacturing. Patients received lymphodepleting chemotherapy with cyclophosphamide for 2 days and fludarabine for 5 days, followed by a single TIL infusion and post-TIL high-dose interleukin (IL)-2. Safety assessments included clinically significant adverse events (AEs). Efficacy assessments included overall response rate (ORR), complete response (CR) rate, disease control rate (DCR), and overall survival. Between October 2011 and August 2019, 21 patients underwent treatment (median follow-up time, 52.2 months from TIL infusion). Among all treated patients, median age was 45 years, median number of disease sites was 4, 100% had M1c or M1d disease, and 90% received prior checkpoint inhibitor. Twelve patients received TILs after prior PD-1 inhibition. The safety profile among all treated patients and the prior PD-1 inhibitor subgroup was generally consistent with lymphodepletion and high-dose IL-2. No treatment-related deaths occurred. Among all patients, the ORR was 67%, CR rate was 19%, and the DCR was 86%, which was consistent with that observed in the prior PD-1 inhibitor subgroup (58%, 8%, and 75%, respectively). Median overall survival in all treated patients and the prior PD-1 inhibitor subgroup was 21.3 months. In total, 5 patients (24%) had durable ongoing responses (>30 months post-TIL infusion) at data cutoff, and all patients who achieved CR remained alive and disease free. To further illustrate how TIL therapy may integrate into established treatment paradigms, several case studies of patients treated in this series were included. Overall, these data demonstrate that manufacturing of nonselected autologous TILs from tumor digests is feasible and resulted in high rates of durable response in poor-risk patient populations, which may address significant unmet medical need.

Adoptive Cell Transfer and Vaccines in Melanoma: The Horizon Comes Into View

Over the past four decades, cancer immunotherapy for melanoma has evolved from single-agent, type-I cytokine therapy to combination immune checkpoint inhibition. Along the way, breakthroughs in the fields of cell therapy and cancer vaccination have been made as well. The early data from adoptive cell therapy, involving the delivery of tumor infiltrating lymphocytes harvested from resected tumors, was generated at the National Cancer Institute. Subsequently, a limited number of centers across the globe have developed programs to deliver these therapies. Recently, more widespread availability of this therapy has been made possible by centralizing the growth and expansion of tumor infiltrating lymphocyte products, then distributing the products for delivery of therapy at numerous academic medical centers. Work is ongoing to optimize these treatments with additional cell types and/or modified cell products, and to determine the best ways of combining these treatments with immune checkpoint inhibition. Similarly, tumor vaccination strategies are undergoing dramatic changes, transitioning the field from peptide-based vaccines to next-generation sequencing and T-cell receptor sequencing. These changes help improve the selection of targeted antigens by finding more immunogenic options, and they help with the development of lipid nanoparticles and mRNA delivery. In short, evolution of the approaches that are revolutionizing infectious disease vaccination has been ongoing, and there are promising preliminary data in patients with melanoma.

Efficacy of Cytokine-Induced Killer Cell Immunotherapy for Patients With Pathologically Pure Glioblastoma

The most common malignant central nervous system tumor is glioblastoma multiforme (GBM). Cytokine-induced killer (CIK) cell therapy is a promising type of adoptive cell immunotherapy for various cancers. We previously conducted a randomized clinical trial on CIK cell therapy in patients with GBM. The aim of this study was to evaluate the efficacy of CIK immunotherapy for patients with pathologically pure GBM, using data from our previous randomized clinical trial. The difference between overall survival (OS) and progression-free survival (PFS) according to CIK immunotherapy was analyzed using the Kaplan–Meier method. Hazard ratios were calculated using univariate and multivariate Cox regression analyses to determine whether CIK cell immunotherapy was independently associated with higher OS and PFS in patients with pure GBM. A total of 156 eligible patients were included in the modified intention-to-treat (mITT) population. We confirmed that 125 (80.1%) GBM samples were pure GBM tumors without the presence of other types of tumors. For patients with pure GBM, Kaplan-Meier analysis showed no significant difference in OS between the CIK cell treatment and control groups. However, multivariate Cox regression demonstrated CIK cell immunotherapy as an independent predictor of greater OS (hazard ratio, 0.59; 95% CI, 0.36–0.97; p = 0.038) and PFS (hazard ratio, 0.55; 95% CI, 0.36–0.84; p = 0.001) in patients with pathologically pure GBM in the mITT population. This study showed that CIK cell immunotherapy combined with conventional temozolomide chemoradiotherapy could prolong OS and PFS in patients with newly diagnosed pathologically pure GBM, with no significant adverse events related to treatment. However, unlike the results of multivariate Cox analysis, no statistical significance of CIK cell immunotherapy in OS in Kaplan-Meier analysis raises a question. Further studies are required to validate these results.

A Toolkit for Profiling the Immune Landscape of Pediatric Central Nervous System Malignancies

The prognosis of pediatric central nervous system (CNS) malignancies remains dismal due to limited treatment options, resulting in high mortality rates and long-term morbidities. Immunotherapies, including checkpoint inhibition, cancer vaccines, engineered T cell therapies, and oncolytic viruses, have promising results in some hematological and solid malignancies, and are being investigated in clinical trials for various high-grade CNS malignancies. However, the role of the tumor immune microenvironment (TIME) in CNS malignancies is mostly unknown for pediatric cases. In order to successfully implement immunotherapies and to eventually predict which patients would benefit from such treatments, in-depth characterization of the TIME at diagnosis and throughout treatment is essential. In this review, we provide an overview of techniques for immune profiling of CNS malignancies, and detail how they can be utilized for different tissue types and studies. These techniques include immunohistochemistry and flow cytometry for quantifying and phenotyping the infiltrating immune cells, bulk and single-cell transcriptomics for describing the implicated immunological pathways, as well as functional assays. Finally, we aim to describe the potential benefits of evaluating other compartments of the immune system implicated by cancer therapies, such as cerebrospinal fluid and blood, and how such liquid biopsies are informative when designing immune monitoring studies. Understanding and uniformly evaluating the TIME and immune landscape of pediatric CNS malignancies will be essential to eventually integrate immunotherapy into clinical practice.

Current Immunotherapeutic Approaches for Malignant Gliomas

Glioblastoma is the most common malignant central nervous system (CNS) tumor (48.3%), with a median survival of only about 14.6 months. Although the CNS is an immune-privileged site, activated T cells can cross the blood-brain barrier. The recent successes of several immunotherapies for various cancers have drawn interest in immunotherapy for treatment of malignant glioma. There have been extensive attempts to evaluate the efficiency of immunotherapy against malignant glioma. Passive immunotherapy for malignant glioma includes monoclonal antibody-mediated immunotherapy, cytokine-mediated therapy, and adoptive cell transfer, also known as chimeric antigen receptor T cell treatment. On the other hand, active immunotherapy, which stimulates the patient’s adaptive immune system against specific tumor-associated antigens, includes cancer vaccines that are divided into peptide vaccines and cell-based vaccines. In addition, there is immune checkpoint blockade therapy, which increases the efficiency of immunotherapy by reducing the resistance of malignant glioma to immunotherapy. Despite centuries of efforts, immunotherapeutic successes for malignant glioma remain limited. However, many clinical trials of adoptive cell transfer immunotherapy on malignant glioma are ongoing, and the outcomes are eagerly awaited. In addition, although there are still several obstacles, current clinical trials using personalized neoantigen-based dendritic cell vaccines offer new hope to glioblastoma patients. Furthermore, immune checkpoint targeted therapy is expected to decipher the mechanism of immunotherapy resistance in malignant glioma in the near future. More studies are needed to increase the efficacy of immunotherapy in malignant glioma. We hope that immunotherapy will become a new treatment of malignant glioma.

The current landscape of immunotherapy for pediatric brain tumors

Pediatric central nervous system tumors are the most common solid malignancies in childhood, and aggressive therapy often leads to long-term sequelae in survivors, making these tumors challenging to treat. Immunotherapy has revolutionized prospects for many cancer types in adults, but the intrinsic complexity of treating pediatric patients and the scarcity of clinical studies of children to inform effective approaches have hampered the development of effective immunotherapies in pediatric settings. Here, we review recent advances and ongoing challenges in pediatric brain cancer immunotherapy, as well as considerations for efficient clinical translation of efficacious immunotherapies into pediatric settings.

Modulation of the blood-tumor barrier to enhance drug delivery and efficacy for brain metastases

The blood-brain barrier is the selectively permeable vasculature of the brain vital for maintaining homeostasis and neurological function. Low permeability is beneficial in the presence of toxins and pathogens in the blood. However, in the presence of metastatic brain tumors, it is a challenge for drug delivery. Although the blood-tumor barrier is slightly leaky, it still is not permissive enough to allow the accumulation of therapeutic drug concentrations in brain metastases. Herein, we discuss the differences between primary brain tumors and metastatic brain tumors vasculature, effects of therapeutics on the blood-tumor barrier, and characteristics to be manipulated for more effective drug delivery.

Harnessing nanomedicine for enhanced immunotherapy for breast cancer brain metastases

Brain metastases (BMs) are the most common type of brain tumor, and the incidence among breast cancer (BC) patients has been steadily increasing over the past two decades. Indeed, ~ 30% of all patients with metastatic BC will develop BMs, and due to few effective treatments, many will succumb to the disease within a year. Historically, patients with BMs have been largely excluded from clinical trials investigating systemic therapies including immunotherapies (ITs) due to limited brain penetration of systemically administered drugs combined with previous assumptions that BMs are poorly immunogenic. It is now understood that the central nervous system (CNS) is an immunologically distinct site and there is increasing evidence that enhancing immune responses to BCBMs will improve patient outcomes and the efficacy of current treatment regimens. Progress in IT for BCBMs, however, has been slow due to several intrinsic limitations to drug delivery within the brain, substantial safety concerns, and few known targets for BCBM IT. Emerging studies demonstrate that nanomedicine may be a powerful approach to overcome such limitations, and has the potential to greatly improve IT strategies for BMs specifically. This review summarizes the evidence for IT as an effective strategy for BCBM treatment and focuses on the nanotherapeutic strategies currently being explored for BCBMs including targeting the blood-brain/tumor barrier (BBB/BTB), tumor cells, and tumor-supporting immune cells for concentrated drug release within BCBMs, as well as use of nanoparticles (NPs) for delivering immunomodulatory agents, for inducing immunogenic cell death, or for potentiating anti-tumor T cell responses.

Using chimeric antigen receptor T-cell therapy to fight glioblastoma multiforme: past, present and future developments

Introduction

Glioblastoma multiforme (GBM) constitutes one of the deadliest tumors to afflict humans, although it is still considered an orphan disease. Despite testing multiple new and innovative therapies in ongoing clinical trials, the median survival for this type of malignancy is less than two years after initial diagnosis, regardless of therapy. One class of promising new therapies are chimeric antigen receptor T cells or CAR-T which have been shown to be very effective at treating refractory liquid tumors such as B-cell malignancies. However, CAR-T effectivity against solid tumors such as GBM has been limited thus far.

Methods

A Pubmed, Google Scholar, Directory of Open Access Journals, and Web of Science literature search using the terms chimeric antigen receptor or CAR-T, GBM, solid tumor immunotherapy, immunotherapy, and CAR-T combination was performed for publication dates between January 1987 and November 2021.

Results

In the current review, we present a comprehensive list of CAR-T cells developed to treat GBM, we describe new possible T-cell engineering strategies against GBM while presenting a short introductory history to the reader regarding the origin(s) of this cutting-edge therapy. We have also compiled a unique list of anti-GBM CAR-Ts with their specific protein sequences and their functions as well as an inventory of clinical trials involving CAR-T and GBM.

Conclusions

The aim of this review is to introduce the reader to the field of T-cell engineering using CAR-Ts to treat GBM and describe the obstacles that may need to be addressed in order to significantly delay the relentless growth of GBM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11060-021-03902-8.

Is There a Role for Immunotherapy in Central Nervous System Cancers?

Glioblastoma has emerged as an immunotherapy-refractory tumor based on negative phase III studies of anti-programmed cell death-1 therapy among newly diagnosed as well as recurrent patients. In addition, although much work on vaccine and cellular approaches is ongoing, therapeutic benefit with these approaches has been underwhelming. Much scientific insight into the multitiered layers of immunosuppression exploited by glioblastoma tumors is emerging that sheds light on the explanation for the disappointing results to date and highlights possible therapeutic avenues that may offer a better likelihood of therapeutic benefit for immune-based therapies.

Convection-enhanced delivery for high-grade glioma

Glioblastoma (GBM) is the most common adult primary malignant brain tumor and is associated with a dire prognosis. Despite multi-modality therapies of surgery, radiation, and chemotherapy, its 5-year survival rate is 6.8%. The presence of the blood-brain barrier (BBB) is one factor that has made GBM difficult to treat. Convection-enhanced delivery (CED) is a modality that bypasses the BBB, which allows the intracranial delivery of therapies that would not otherwise cross the BBB and avoids systemic toxicities. This review will summarize prior and ongoing studies and highlights practical considerations related to clinical care to aid providers caring for a high-grade glioma patient being treated with CED. Although not the main scope of this paper, this review also touches upon relevant technical considerations of using CED, an area still under much development.

Delivery strategies for cell-based therapies in the brain: overcoming multiple barriers

Cell-based therapies to the brain are promising for the treatment of multiple brain disorders including neurodegeneration and cancers. In order to access the brain parenchyma, there are multiple physiological barriers that must be overcome depending on the route of delivery. Specifically, the blood-brain barrier has been a major difficulty in drug delivery for decades, and it still presents a challenge for the delivery of therapeutic cells. Other barriers, including the blood-cerebrospinal fluid barrier and lymphatic-brain barrier, are less explored, but may offer specific challenges or opportunities for therapeutic delivery. Here we discuss the barriers to the brain and the strategies currently in place to deliver cell-based therapies, including engineered T cells, dendritic cells, and stem cells, to treat diseases. With a particular focus on cancers, we also highlight the current ongoing clinical trials that use cell-based therapies to treat disease, many of which show promise at treating some of the deadliest illnesses.

T-Cell Immunotherapy for Pediatric High-Grade Gliomas: New Insights to Overcoming Therapeutic Challenges

Despite decades of research, pediatric central nervous system (CNS) tumors remain the most debilitating, difficult to treat, and deadliest cancers. Current therapies, including radiation, chemotherapy, and/or surgery, are unable to cure these diseases and are associated with serious adverse effects and long-term impairments. Immunotherapy using chimeric antigen receptor (CAR) T cells has the potential to elucidate therapeutic antitumor immune responses that improve survival without the devastating adverse effects associated with other therapies. Yet, despite the outstanding performance of CAR T cells against hematologic malignancies, they have shown little success targeting brain tumors. This lack of efficacy is due to a scarcity of targetable antigens, interactions with the immune microenvironment, and physical and biological barriers limiting the homing and trafficking of CAR T cells to brain tumors. In this review, we summarize experiences with CAR T-cell therapy for pediatric CNS tumors in preclinical and clinical settings and focus on the current roadblocks and novel strategies to potentially overcome those therapeutic challenges.

Chimeric Antigen Receptor (CAR) T Cell Therapy for Glioblastoma

Glioblastoma (GBM) are the most common and aggressive primary brain tumors in adults. Current mainstay treatments include surgery, chemotherapy, and radiation; however, these are ineffective. As a result, immunotherapy treatment strategies are being developed to harness the body's natural defense mechanisms against gliomas. Adoptive cell therapy with chimeric antigen receptor (CAR) T cells uses patients' own T cells that are genetically modified to target tumor-associated antigens. These cells are harvested from patients, engineered to target specific proteins expressed by the tumor and re-injected into the patient with the goal of destroying tumor cells. In this mini review, we outline the history of CAR T cell therapy, describe current antigen targets, and review challenges this treatment faces specifically in targeting GBM.

Oncolytic Virotherapy for Melanoma Brain Metastases, a Potential New Treatment Paradigm?

INTRODUCTION

Melanoma brain metastases remain a devastating disease process with poor prognosis. Recently, there has been a surge in studies demonstrating the efficacy of oncolytic virotherapy for brain tumor treatment. Given their specificity and amenability to genetic modification, the authors explore the possible role of oncolytic virotherapy as a potential treatment option for patients with melanoma brain metastases.

METHODS

A comprehensive literature review including both preclinical and clinical evidence of oncolytic virotherapy for the treatment of melanoma brain metastasis was performed.

RESULTS

Oncolytic virotherapy, specifically T-VEC (Imlygic™), was approved for the treatment of melanoma in 2015. Recent clinical trials demonstrate promising anti-tumor changes in patients who have received T-VEC; however, there is little evidence for its use in metastatic brain disease based on the existing literature. To date, only two single cases utilizing virotherapy in patients with metastatic brain melanoma have been reported, specifically in patients with treatment refractory disease. Currently, there is not sufficient data to support the use of T-VEC or other viruses for intracranial metastatic melanoma. In developing a virotherapy treatment paradigm for melanoma brain metastases, several factors must be considered, including route of administration, need to bypass the blood-brain barrier, viral tumor infectivity, and risk of adverse events.

CONCLUSIONS

Evidence for oncolytic virotherapy treatment of melanoma is limited primarily to T-VEC, with a noticeable paucity of data in the literature with respect to brain tumor metastasis. Given the promising findings of virotherapy for other brain tumor types, oncolytic virotherapy has great potential to offer benefits to patients afflicted with melanoma brain metastases and warrants further investigation.

Novel Allosteric Inhibitors of Deoxyhypusine Synthase against Malignant Melanoma: Design, Synthesis, and Biological Evaluation

Based on the novel allosteric site of deoxyhypusine synthase (DHPS), two series of 30 novel 5-(2-methoxyphenoxy)-2-phenylpyrimidin-4-amine derivatives as DHPS inhibitors were designed and synthesized. Among them, compound 8m, with the best DHPS inhibitory potency (IC50 = 0.014 μM), exhibited excellent inhibition against melanoma cells, which was superior to that of GC7. Besides, molecular docking and molecular dynamics (MD) simulations further proved that compound 8m was tightly bound to the allosteric site of DHPS. Flow cytometric analysis and enzyme-linked immunosorbent assay (ELISA) showed that compound 8m could inhibit the intracellular reactive oxygen species (ROS) level. Furthermore, by western blot analysis, compound 8m effectively activated caspase 3 and decreased the expressions of GP-100, tyrosinase, eIF5A2, MMP2, and MMP9. Moreover, both Transwell analysis and wound healing analysis showed that compound 8m could inhibit the invasion and migration of melanoma cells. In the in vivo study, the tumor xenograft model showed that compound 8m effectively inhibited melanoma development with low toxicity.

Increased antitumor efficacy of PD-1-deficient melanoma-specific human lymphocytes

Background

Genome editing offers unique perspectives for optimizing the functional properties of T cells for adoptive cell transfer purposes. So far, PDCD1 editing has been successfully tested mainly in chimeric antigen receptor T (CAR-T) cells and human primary T cells. Nonetheless, for patients with solid tumors, the adoptive transfer of effector memory T cells specific for tumor antigens remains a relevant option, and the use of high avidity T cells deficient for programmed cell death-1 (PD-1) expression is susceptible to improve the therapeutic benefit of these treatments.

Methods

Here we used the transfection of CAS9/sgRNA ribonucleoproteic complexes to edit PDCD1 gene in human effector memory CD8⁺ T cells specific for the melanoma antigen Melan-A. We cloned edited T cell populations and validated PDCD1 editing through sequencing and cytometry in each T cell clone, together with T-cell receptor (TCR) chain’s sequencing. We also performed whole transcriptomic analyses on wild-type (WT) and edited T cell clones. Finally, we documented in vitro and in vivo through adoptive transfer in NOD scid gamma (NSG) mice, the antitumor properties of WT and PD-1KO T cell clones, expressing the same TCR.

Results

Here we demonstrated the feasibility to edit PDCD1 gene in human effector memory melanoma-specific T lymphocytes. We showed that PD-1 expression was dramatically reduced or totally absent on PDCD1-edited T cell clones. Extensive characterization of a panel of T cell clones expressing the same TCR and exhibiting similar functional avidity demonstrated superior antitumor reactivity against a PD-L1 expressing melanoma cell line. Transcriptomic analysis revealed a downregulation of genes involved in proliferation and DNA replication in PD-1-deficient T cell clones, whereas genes involved in metabolism and cell signaling were upregulated. Finally, we documented the superior ability of PD-1-deficient T cells to significantly delay the growth of a PD-L1 expressing human melanoma tumor in an NSG mouse model.

Conclusion

The use of such lymphocytes for adoptive cell transfer purposes, associated with other approaches modulating the tumor microenvironment, would be a promising alternative to improve immunotherapy efficacy in solid tumors.

The State of Immunotherapy in Hepatobiliary Cancers

Hepatobiliary cancers, including hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), and gallbladder carcinoma (GBC), are lethal cancers with limited therapeutic options. Curative-intent treatment typically involves surgery, yet recurrence is common and many patients present with advanced disease not amenable to an operation. Immunotherapy represents a promising approach to improve outcomes, but the immunosuppressive tumor microenvironment of the liver characteristic of hepatobiliary cancers has hampered the development and implementation of this therapeutic approach. Current immunotherapies under investigation include immune checkpoint inhibitors (ICI), the adoptive transfer of immune cells, bispecific antibodies, vaccines, and oncolytic viruses. Programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) are two ICIs that have demonstrated utility in HCC, and newer immune checkpoint targets are being tested in clinical trials. In advanced CCA and GBC, PD-1 ICIs have resulted in antitumor responses, but only in a minority of select patients. Other ICIs are being investigated for patients with CCA and GBC. Adoptive transfer may hold promise, with reports of complete durable regression in metastatic CCA, yet this therapeutic approach may not be generalizable. Alternative approaches have been developed and promising results have been observed, but clinical trials are needed to validate their utility. While the treatment of hepatobiliary cancers involves unique challenges that these cancers present, the progress seen with ICIs and adoptive transfer has solidified immunotherapy as an important approach in these challenging patients with few other effective treatment options.

Role of Surgery in Stage IV Melanoma

Stage IV melanoma has a 5-year survival rate of 6%, but considerable advances have been made in systemic therapies. Systemic immunotherapy has achieved durable responses in up to 40% of patients, with similar improvements with targeted therapies. This has reshaped the landscape for surgery in stage IV melanoma. Metastasectomy can be considered in patients on systemic immunotherapy or targeted therapy with responding, stable, or isolated progressing lesions, oligometastatic disease, or long disease-free intervals. Surgery plays a role in providing tumor tissue for preparation of tumor-infiltrating lymphocytes for adoptive cell therapy. Surgical palliation plays a role in patients with symptomatic metastases.

Chimeric Antigen Receptor T-Cell Therapy: Updates in Glioblastoma Treatment

Glioblastoma multiforme (GBM) are the most common and among the deadliest brain tumors in adults. Current mainstay treatments are insufficient to treat this tumor, and therefore, more effective therapies are desperately needed. Immunotherapy, which takes advantage of the body's natural defense mechanism, is an exciting emerging field in neuro-oncology. Adoptive cell therapy with chimeric antigen receptor (CAR) T cells provides a treatment strategy based on using patients' own selected and genetically engineered cells that target tumor-associated antigens. These cells are harvested from patients, modified to target specific proteins expressed by the tumor, and re-introduced into the patient with the goal of destroying tumor cells. Here, we review the history of CAR T-cell therapy, and describe the characteristics of various generations of CAR T therapies, and the challenges inherent to treatment of GBM. Finally, we describe recent and current CAR T clinical trials designed to combat GBM.

ACT Up TIL Now: The Evolution of Tumor-Infiltrating Lymphocytes in Adoptive Cell Therapy for the Treatment of Solid Tumors

The past decades of cancer immunotherapy research have provided profound evidence that the immune system is capable of inducing durable tumor regression. Although many commercialized anti-cancer immunotherapies are available to patients, these treatment options only scrape the surface of the potential immune-related treatment possibilities for cancer. Additionally, many individuals are ineligible for established immunotherapies due to their cancer type. The adoptive cell transfer of autologous tumor-infiltrating lymphocytes has been used in humans for over 30 years to treat metastatic melanoma, and continued modifications are making it increasingly more effective against other types of cancer. This comprehensive review outlines this therapy from its infancy through to the present day, bringing to light modifications and optimizations to the traditional workflow, as well as highlighting the influence of new methods and technologies.

Current progress in chimeric antigen receptor T cell therapy for glioblastoma multiforme

Glioblastoma multiforme (GBM) is one of the deadliest brain tumors with an unfavorable prognosis and overall survival of approximately 20 months following diagnosis. The current treatment for GBM includes surgical resections and chemo‐ and radiotherapeutic modalities, which are not effective. CAR‐T immunotherapy has been proven effective for CD19‐positive blood malignancies, and the application of CAR‐T cell therapy for solid tumors including GBM offers great hope for this aggressive tumor which has a limited response to current treatments. CAR‐T technology depends on the use of patient‐specific T cells genetically engineered to express specific tumor‐associated antigens (TAAs). Interaction of CAR‐T cells with tumor cells triggers the destruction/elimination of these cells by the induction of cytotoxicity and the release of different cytokines. Despite the great promise of CAR‐T cell‐based therapy several challenges exist. These include the heterogeneity of GBM cancer cells, aberrant various signaling pathways involved in tumor progression, antigen escape, the hostile inhibitory GBM microenvironment, T cell dysfunction, blood‐brain barrier, and defective antigen presentation. All need to be addressed before full application at the clinical level can begin. Herein we provide a focused review of the rationale for the use of different types of CAR‐T cells (including FcγRs), the different GBM‐associated antigens, the challenges still facing CAR‐T‐based therapy, and means to overcome such challenges. Finally, we enumerate currently completed and ongoing clinical trials, highlighting the different ways such trials are designed to overcome specific problems. Exploitation of the full potential of CAR‐T cell therapy for GBM depends on their solution.

Cell Therapy With TILs: Training and Taming T Cells to Fight Cancer

The rationale behind cancer immunotherapy is based on the unequivocal demonstration that the immune system plays an important role in limiting cancer initiation and progression. Adoptive cell therapy (ACT) is a form of cancer immunotherapy that utilizes a patient’s own immune cells to find and eliminate tumor cells, however, donor immune cells can also be employed in some cases. Here, we focus on T lymphocyte (T cell)-based cancer immunotherapies that have gained significant attention after initial discoveries that graft-versus-tumor responses were mediated by T cells. Accumulating knowledge of T cell development and function coupled with advancements in genetics and data science has enabled the use of a patient’s own (autologous) T cells for ACT (TIL ACTs). In TIL ACT, tumor-infiltrating lymphocytes (TILs) are collected from resected tumor material, enhanced and expanded ex-vivo, and delivered back to the patient as therapeutic agents. ACT with TILs has been shown to cause objective tumor regression in several types of cancers including melanoma, cervical squamous cell carcinoma, and cholangiocarcinoma. In this review, we provide a brief history of TIL ACT and discuss the current state of TIL ACT clinical development in solid tumors. We also discuss the niche of TIL ACT in the current cancer therapy landscape and potential strategies for patient selection.

Generating CAR T cells from tumor-infiltrating lymphocytes

Background: Tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T-cell therapies have demonstrated promising, though limited, efficacy against melanoma. Methods: We designed a model system to explore the efficacy of dual specific T cells derived from melanoma patient TILs by transduction with a Her2-specific CAR. Results: Metastatic melanoma cells in our biobank constitutively expressed Her2 antigen. CAR-TIL produced greater amounts of IFN compared with parental TIL, when co-cultured with Her2 expressing tumor lines, including autologous melanoma tumor lines, although no consistent increase in cytotoxicity by TIL was afforded by expression of a CAR. Results of an in vivo study in NSG mice demonstrated tumor shrinkage when CAR-TILs were used in an adoptive cell therapy protocol. Conclusion: Potential limitations of transduced TIL in our study included limited proliferative potential and a terminally differentiated phenotype, which would need addressing in further work before consideration of clinical translation.

Recruitment, Infiltration, and Cytotoxicity of HLA-Independent Killer Lymphocytes in Three-Dimensional Melanoma Models

Simple Summary

Limited therapeutic results of immune checkpoint inhibitors in definite tumor settings, such as melanoma, call for alternative or complementary approaches. Among these, adoptive cell therapy (ACT) by means of HLA-independent tumor killer lymphocytes is a promising approach. We aimed at developing a pre-clinical 3D model to investigate and visualize the interaction between tumor and immune effectors in melanoma. To this aim, we employed Cytokine-Induced Killer cells (CIK) and NK-92 on patient-derived melanoma samples. By means of imaging-based methods, we measured the effector recruitment on the 3D targets, their infiltration, and cytotoxic activity. Our results and methodologies can be easily generalized to other effectors and other classes of tumors and help elucidate fundamental questions on the basic biology and kinetics of immune effector recruitment in a realistic 3D setting mimicking a solid tumor.

Abstract

Cancer adoptive cell therapy (ACT) with HLA-independent tumor killer lymphocytes is a promising approach, with intrinsic features potentially addressing crucial tumor-escape mechanisms of checkpoint inhibitors. Cytokine-induced Killer (CIK) and Natural Killer (NK) lymphocytes share similar tumor-killing mechanisms, with preclinical evidence of intense activity against multiple solid tumors and currently testing in clinical studies. To improve the effective clinical translation of such ACT approaches, several fundamental questions still need to be addressed within appropriate preclinical contexts, capable of overcoming limitations imposed by most traditional two-dimensional assays. Here, we developed a novel experimental approach to explore, dissect, and visualize the interactions of CIK and NK lymphocytes with melanoma tumors in vitro in 3D. Primary melanoma cells were assembled into small tumors that were dispersed in a 3D matrix and challenged with patient-derived CIK or the NK-92 cell line. By means of imaging-based methods, we reported, visualized, and quantitatively measured the recruitment of CIK and NK on the 3D targets, their infiltration, and cytotoxic activity. Our results support the effective tumor recruitment and tumor infiltration by CIK and NK. Such features appeared dependent on the specific geometric aspects of the environment but can be explained in terms of directional migration toward the tumor, without invoking major feedback components. Overall, our 3D platform allows us to monitor the processes of tumor recruitment, infiltration, and killing by means of live measurements, revealing important kinetic aspects of ACT with CIK and NK against melanoma.

The Network of Cytokines in Brain Metastases

Brain metastases are the most common of all intracranial tumors and a major cause of death in patients with cancer. Cytokines, including chemokines, interferons, interleukins, lymphokines, and tumor necrosis factors are key regulators in the formation of brain metastases. They regulate the infiltration of different cellular subsets into the tumor microenvironment and affect the therapeutic outcomes in patients. Elucidating the cancer cell-cytokine interactions in the setting of brain metastases is crucial for the development of more accurate diagnostics and efficacious therapies. In this review, we focus on cytokines that are found in the tumor microenvironment of brain metastases and elaborate on their trends of expression, regulation, and roles in cellular recruitment and tumorigenesis. We also explore how cytokines can alter the anti-tumor response in the context of brain metastases and discuss ways through which cytokine networks can be manipulated for diagnosis and treatment.

Immune Therapy for Central Nervous System Metastasis

Brain metastases lead to substantial morbidity and mortality among patients with advanced malignancies. Although treatment options have traditionally included largely palliative measures, studies of brain metastasis response to immunotherapy are promising. Immune checkpoint inhibitors have shown efficacy in studies of patients with melanoma, renal cell carcinoma, and lung cancer brain metastases. Patients with brain metastases are more frequently included in clinical trials, ushering in a new era in immunotherapy and management for patients with brain metastases. Gaining an understanding of the molecular determination for response to immunotherapies remains a major challenge and is an active area of future research.

Bioactivity and safety of B7-H3-targeted chimeric antigen receptor T cells against anaplastic meningioma

Objective

We conducted a first‐in‐human study to evaluate the bioactivity and safety of B7‐H3‐targeted chimeric antigen receptor (CAR) autologous T cells for treating recurrent anaplastic meningioma.

Methods

Tumor tissues from a patient with recurrent anaplastic meningioma were evaluated for B7‐H3 expression. B7‐H3‐targeted CAR‐T cells were delivered into the intracranial tumor resection cavity using an Ommaya device at a maximum dose of 1.5 × 10⁷ cells. Magnetic resonance imaging (MRI) screening and multiple serum indexes were regularly monitored. The patient received surgical intervention after three‐cycle infusions, allowing analysis for CAR‐T‐cell infiltration and target antigen expression in post‐CAR‐T therapy tumor tissues.

Results

Immunochemical analysis demonstrated high and homogeneous B7‐H3 expression in tumor samples. MRI results indicated that the tumor near the delivery device was relatively stable compared with the rapid progression of tumors distant from the device. We found CAR‐T‐cell trafficking to regions of B7‐H3⁺ tumor tissues near the device, but not to tumor tissues distant from the device. Decreased B7‐H3 expression was observed near the region of CAR‐T‐cell infiltration after therapy. The intracavitary delivery of B7‐H3‐targeted CAR‐T cells was well‐tolerated and not associated with any toxic effects of grade 3 or higher.

Conclusion

Our results suggested that although intracavitary administration of B7‐H3‐targeted CAR‐T cells was safe and resulted in local bioactivity, addressing antigen loss and CAR‐T‐cell trafficking may further enhance the applications of B7‐H3‐targeted CAR‐T‐cell therapy.

Pilot Trial of Adoptive Transfer of Chimeric Antigen Receptor-transduced T Cells Targeting EGFRvIII in Patients With Glioblastoma

A deletion variant of epidermal growth factor receptor (EGFRvIII) is a known driver mutation in a subset of primary and secondary glioblastoma multiforme. Adoptive transfer of genetically modified chimeric antigen receptor (CAR) lymphocytes has demonstrated efficacy in hematologic malignancies but is still early in development for solid cancers. The surface expression of the truncated extracellular ligand domain created by EGFRvIII makes it an attractive target for a CAR-based cancer treatment. Patients with recurrent glioblastoma expressing EGFRvIII were enrolled in a dose escalation phase I trial, using a third-generation CAR construct derived from a human antibody. Transduced cells were administered after lymphodepleting chemotherapy and supported posttransfer with intravenous interleukin-2. The dose escalation proceeded at half-log increments from 10 to >10 cells. Primary endpoints were safety and progression-free survival. Eighteen patients were treated with final infusion products ranging from 6.3×10 to 2.6×10 anti-EGFRvIII CAR T cells. Median progression-free survival was 1.3 months (interquartile range: 1.1-1.9), with a single outlier of 12.5 months. Two patients experienced severe hypoxia, including one treatment-related mortality after cell administration at the highest dose level. All patients developed expected transient hematologic toxicities from preparative chemotherapy. Median overall survival was 6.9 months (interquartile range: 2.8-10). Two patients survived over 1 year, and a third patient was alive at 59 months. Persistence of CAR cells correlated with cell dose, but there were no objective responses. Administration of anti-EGFRvIII CAR-transduced T cells did not demonstrate clinically meaningful effect in patients with glioblastoma multiforme in this phase I pilot trial.

Current Treatment of Melanoma Brain Metastasis

OPINION STATEMENT

With greater understanding of underlying biology and development of effective BRAF-targeted therapy and immunotherapy, along with remarkable advances in local treatment such as stereotactic radiosurgery, melanoma brain metastasis (MBM) is witnessing continually improving outcome, with 1-year overall survival rate approaching 85%. Given disease complexity and myriad treatment options, all patients with MBM should ideally be evaluated in a multidisciplinary setting to allow an individualized treatment approach based on prognostic groups, molecular classification, number and size of brain metastasis, and performance status. With improving outcome, pendulum has now swayed to focus more on effective treatment modalities with minimal neurological toxicity while maintaining quality of life. Surgery is usually considered in symptomatic and large MBMs, while stereotactic radiosurgery considered in 1-4 lesions, and now also being explored for up to 15 brain metastases for improved local control. The role of whole brain radiotherapy is diminishing given its neurocognitive toxicities and is reserved for patients with diffuse brain involvement. Cytotoxic chemotherapy has largely been ineffective without evidence for survival benefit. Immune checkpoint inhibitors have become the cornerstone of management for melanoma brain metastasis with durable intracranial tumor control and excellent toxicity profile. For patients with asymptomatic MBMs, ipilimumab and nivolumab have shown intracranial response near 60% and provides comparable clinical benefit in MBMs as for extracranial metastases. For patients with driver BRAF mutation, BRAFi-/MEKi-targeted agents are proven to be effective in MBM with high rate intracranial responses (44-59%). However, the durability of intracranial responses induced by BRAFi/MEKi seems to be shorter than that of extracranial disease. Emerging data support novel combination of systemic therapy and stereotactic radiosurgery, which appears to be safe and effective; however, potential benefits and risks should be evaluated prospectively. Promising ongoing trials will further expand therapeutic evidence in MBM, and patients should be encouraged to participate in clinical trials.

Adoptive Cell Therapy: A Novel and Potential Immunotherapy for Glioblastoma

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults with very poor prognosis and few advances in its treatment. Recently, fast-growing cancer immunotherapy provides a glimmer of hope for GBM treatment. Adoptive cell therapy (ACT) aims at infusing immune cells with direct anti-tumor activity, including tumor-infiltrating lymphocyte (TIL) transfer and genetically engineered T cells transfer. For example, complete regressions in patients with melanoma and refractory lymphoma have been shown by using naturally tumor-reactive T cells and genetically engineered T cells expressing the chimeric anti-CD19 receptor, respectively. Recently, the administration of ACT showed therapeutic potentials for GBM treatment as well. In this review, we summarize the success of ACT in the treatment of cancer and provide approaches to overcome some challenges of ACT to allow its adoption for GBM treatment.

CAR T cells for brain tumors: Lessons learned and road ahead

Malignant brain tumors, including glioblastoma, represent some of the most difficult to treat of solid tumors. Nevertheless, recent progress in immunotherapy, across a broad range of tumor types, provides hope that immunological approaches will have the potential to improve outcomes for patients with brain tumors. Chimeric antigen receptors (CAR) T cells, a promising immunotherapeutic modality, utilizes the tumor targeting specificity of any antibody or receptor ligand to redirect the cytolytic potency of T cells. The remarkable clinical response rates of CD19-targeted CAR T cells and early clinical experiences in glioblastoma demonstrating safety and evidence for disease modifying activity support the potential of further advancements ultimately providing clinical benefit for patients. The brain, however, is an immune specialized organ presenting unique and specific challenges to immune-based therapies. Remaining barriers to be overcome for achieving effective CAR T cell therapy in the central nervous system (CNS) include tumor antigenic heterogeneity, an immune-suppressive microenvironment, unique properties of the CNS that limit T cell entry, and risks of immune-based toxicities in this highly sensitive organ. This review will summarize preclinical and clinical data for CAR T cell immunotherapy in glioblastoma and other malignant brain tumors, including present obstacles to advancement.

The impact of current treatment modalities on the outcomes of patients with melanoma brain metastases: A systematic review

Patients with melanoma brain metastases (MBM) still have a very poor prognosis. Several treatment modalities have been investigated in an attempt to improve the management of MBM. This review aimed to evaluate the impact of current treatments for MBM on patient‐ and tumor‐related outcomes, and to provide treatment recommendations for this patient population. A literature search in the databases PubMed, Embase, Web of Science and Cochrane was conducted up to January 8, 2019. Original articles published since 2010 describing patient‐ and tumor‐related outcomes of adult MBM patients treated with clearly defined systemic therapy were included. Information on basic trial demographics, treatment under investigation and outcomes (overall and progression‐free survival, local and distant control and toxicity) were extracted. We identified 96 eligible articles, comprising 95 studies. A large variety of treatment options for MBM were investigated, either used alone or as combined modality therapy. Combined modality therapy was investigated in 71% of the studies and resulted in increased survival and better distant/local control than monotherapy, especially with targeted therapy or immunotherapy. However, neurotoxic side‐effects also occurred more frequently. Timing appeared to be an important determinant, with the best results when radiotherapy was given before or during systemic therapy. Improved tumor control and prolonged survival can be achieved by combining radiotherapy with immunotherapy or targeted therapy. However, more randomized controlled trials or prospective studies are warranted to generate proper evidence that can be used to change the standard of care for patients with MBM.

High Endogenous DNA Damage Levels Predict Hematological Toxicity in Testicular Germ Cell Tumor Patients Treated With First-Line Chemotherapy

BACKGROUND

Testicular germ cell tumors (TGCTs) are an excellent example of chemosensitive disease. However, cisplatin-based chemotherapy has significant side effects, including myelosuppression. Previously, we found endogenous DNA damage level in peripheral blood mononuclear cells (PBMCs) to be an independent prognostic marker. In this study, we tested the hypothesis that patients with high endogenous DNA damage levels in PBMCs have an increased risk of developing hematological toxicity.

PATIENTS AND METHODS

One hundred twenty chemotherapy-naive TGCT patients treated in the National Cancer Institute and the St Elisabeth Cancer Institute in Bratislava, Slovakia, from 2012 to 2018 were enrolled. All patients received platinum-based chemotherapy with granulocyte colony stimulating factor support. On the day of starting treatment, we measured the DNA damage levels in PBMCs using the comet assay. We used the cutoff level of 5.25, a value previously reported to stratify patients on the basis of their prognosis. We monitored hematological toxicity during the first cycle of chemotherapy. The mean and standard error of the mean were calculated for all variables.

RESULTS

Patients with high DNA damage levels (>5.25) had more significant hematological toxicity with significantly lower nadir white blood cell count (P = .001), absolute neutrophil count (P = .013) and absolute lymphocyte count (ALC; P < .001). ALCs on day 0 (P = .005) and day 22 (P = .046) were also significantly lower in patients with high DNA damage levels.

CONCLUSION

This study shows that higher endogenous DNA damage levels correlate with increased risk of hematological toxicity in TGCT patients. Hence, the DNA damage levels can be used to select patients for closer monitoring because of a higher risk of acute chemotherapy-related complications.

Clinical chimeric antigen receptor-T cell therapy: a new and promising treatment modality for glioblastoma

Chimeric antigen receptor (CAR)-T cell therapy is now approved in the United States and Europe as a standard treatment for relapsed/refractory B-cell malignancies. It has also been approved recently by the Therapeutic Goods Administration in Australia and may soon be publicly reimbursed. This advance has accentuated scientific, clinical and commercial interest in adapting this exciting technology for the treatment of solid cancers where it is widely recognised that the challenges of overcoming a hostile tumor microenvironment are most acute. Indeed, CAR-T cell technology may be of the greatest value for those cancers that lack pre-existing immunity because they are immunologically 'cold', or have a low somatic tumor mutation load, or both. These cancers are generally not amenable to therapeutic immune checkpoint blockade, but CAR-T cell therapy may be effective because it provides an abundant supply of autologous tumor-specific T cells. This is achieved by using genetic engineering to re-direct autologous T-cell cytotoxicity towards a tumor-associated antigen, bypassing endogenous T-cell requirements for antigen processing, MHC-dependent antigen presentation and co-stimulation. One of the most challenging solid cancers is glioblastoma, which has among the least permissive immunological milieu of any cancer, and which is almost always fatal. Here, we argue that CAR-T cell technology may counter some glioblastoma defences and provide a beachhead for furthering our eventual therapeutic aims of restoring effective antitumor immunity. Although clinical investigation of CAR-T cell therapy for glioblastoma is at an early stage, we discuss three recently published studies, which feature significant differences in target antigen, CAR-T cell phenotype, route of administration and tumor response. We discuss the lessons, which may be learned from these studies and which may guide further progress in the field.

Lymphokine-activated killer cell transplantation after anti-cancer treatment in two aged cats

Immunotherapy improves both survival and remission rates after cancer surgery in humans, but its veterinary use has been limited. We determined the safety and feasibility of lymphokine-activated killer (LAK) cell transplantation in two aged cats that had undergone surgery for malignancy. Case 1 involved an 18-year-old male Japanese domestic cat. The cat exhibited appetite loss and poor physical activity after the surgical excision of oral squamous cell carcinoma followed by four sessions of radiotherapy, and the owner strongly requested immunotherapy for preventing further deterioration in the animal’s quality of life (QOL). We subsequently administered LAK cells three times during a 2-month period. Case 2 involved a 20-year-old female Japanese domestic cat who had undergone mammectomy after a diagnosis of breast adenocarcinoma. The owner strongly requested immunotherapy for QOL maintenance. We administered LAK cells four times over a period of 5 months. Autologous peripheral blood mononuclear cells (PBMCs) fractionated using density gradient centrifugation were cultured in the media containing a high concentration of interleukin-2 and supplemented with 2.5% fetal calf serum. The derived LAK cells were centrifuged, suspended in 10 ml of saline containing 1% of the subject’s own blood, and infused into the cephalic vein of the cats over 30 min. The composition ratios of CD3, CD4, CD8, and CD21 were evaluated by flow cytometry. Bacterial culture and endotoxin testing for a sample of LAK cells showed negative results in both the cases. The leukocyte and erythrocyte counts and the body temperature were assessed on days 7, 14, and 21 after the transfusion. No abnormal signs were observed in either case, which confirmed the safety of the procedure. QOL scores showed no significant changes after the treatment, and the body temperature remained steady throughout the treatment. The findings from these cases suggest that the transplantation of LAK cells derived from PBMCs may be safe and feasible for use in cats, regardless of their age.