Profound impairment of adaptive immune responses by alkylating chemotherapy

The need for paradigm shift: prognostic significance and implications of standard therapy-related systemic immunosuppression in glioblastoma for immunotherapy and oncolytic virotherapy

Despite significant advances in our knowledge regarding the genetics and molecular biology of gliomas over the past two decades and hundreds of clinical trials, no effective therapeutic approach has been identified for adult patients with newly diagnosed glioblastoma, and overall survival remains dismal. Great hopes are now placed on combination immunotherapy. In clinical trials, immunotherapeutics are generally tested after standard therapy (radiation, temozolomide, and steroid dexamethasone) or concurrently with temozolomide and/or steroids. Only a minor subset of patients with progressive/recurrent glioblastoma have benefited from immunotherapies. In this review, we comprehensively discuss standard therapy-related systemic immunosuppression and lymphopenia, their prognostic significance, and the implications for immunotherapy/oncolytic virotherapy. The effectiveness of immunotherapy and oncolytic virotherapy (viro-immunotherapy) critically depends on the activity of the host immune cells. The absolute counts, ratios, and functional states of different circulating and tumor-infiltrating immune cell subsets determine the net immune fitness of patients with cancer and may have various effects on tumor progression, therapeutic response, and survival outcomes. Although different immunosuppressive mechanisms operate in patients with glioblastoma/gliomas at presentation, the immunological competence of patients may be significantly compromised by standard therapy, exacerbating tumor-related systemic immunosuppression. Standard therapy affects diverse immune cell subsets, including dendritic, CD4+, CD8+, natural killer (NK), NKT, macrophage, neutrophil, and myeloid-derived suppressor cell (MDSC). Systemic immunosuppression and lymphopenia limit the immune system's ability to target glioblastoma. Changes in the standard therapy are required to increase the success of immunotherapies. Steroid use, high neutrophil-to-lymphocyte ratio (NLR), and low post-treatment total lymphocyte count (TLC) are significant prognostic factors for shorter survival in patients with glioblastoma in retrospective studies; however, these clinically relevant variables are rarely reported and correlated with response and survival in immunotherapy studies (e.g., immune checkpoint inhibitors, vaccines, and oncolytic viruses). Our analysis should help in the development of a more rational clinical trial design and decision-making regarding the treatment to potentially improve the efficacy of immunotherapy or oncolytic virotherapy.

Intratumoral drug-releasing microdevices allow in situ high-throughput pharmaco phenotyping in patients with gliomas

The lack of reliable predictive biomarkers to guide effective therapy is a major obstacle to the advancement of therapy for high-grade gliomas, particularly glioblastoma (GBM), one of the few cancers whose prognosis has not improved over the past several decades. With this pilot clinical trial (number NCT04135807), we provide first-in-human evidence that drug-releasing intratumoral microdevices (IMDs) can be safely and effectively used to obtain patient-specific, high-throughput molecular and histopathological drug response profiling. These data can complement other strategies to inform the selection of drugs based on their observed antitumor effect in situ. IMDs are integrated into surgical practice during tumor resection and remain in situ only for the duration of the otherwise standard operation (2 to 3 hours). None of the six enrolled patients experienced adverse events related to the IMD, and the exposed tissue was usable for downstream analysis for 11 out of 12 retrieved specimens. Analysis of the specimens provided preliminary evidence of the robustness of the readout, compatibility with a wide array of techniques for molecular tissue interrogation, and promising similarities with the available observed clinical-radiological responses to temozolomide. From an investigational aspect, the amount of information obtained with IMDs allows characterization of tissue effects of any drugs of interest, within the physiological context of the intact tumor, and without affecting the standard surgical workflow.

Immunotherapy Approaches in Isocitrate-Dehydrogenase-Mutant Low-Grade Glioma

Low-grade gliomas (LGGs) are slow-growing tumors in the central nervous system (CNS). Patients characteristically show the onset of seizures or neurological deficits due to the predominant LGG location in high-functional brain areas. As a molecular hallmark, LGGs display mutations in the isocitrate dehydrogenase (IDH) enzymes, resulting in an altered cellular energy metabolism and the production of the oncometabolite D-2-hydroxyglutarate. Despite the remarkable progress in improving the extent of resection and adjuvant radiotherapy and chemotherapy, LGG remains incurable, and secondary malignant transformation is often observed. Therefore, novel therapeutic approaches are urgently needed. In recent years, immunotherapeutic strategies have led to tremendous success in various cancer types, but the effect of immunotherapy against glioma has been limited due to several challenges, such as tumor heterogeneity and the immunologically "cold" tumor microenvironment. Nevertheless, recent preclinical and clinical findings from immunotherapy trials are encouraging and offer a glimmer of hope for treating IDH-mutant LGG patients. Here, we aim to review the lessons learned from trials involving vaccines, T-cell therapies, and IDH-mutant inhibitors and discuss future approaches to enhance the efficacy of immunotherapies in IDH-mutant LGG.

The Current Status, Challenges, and Future Potential of Therapeutic Vaccination in Glioblastoma

Glioblastoma (GBM) is the most common malignant primary brain tumor and confers a dismal prognosis. With only two FDA-approved therapeutics showing modest survival gains since 2005, there is a great need for the development of other disease-targeted therapies. Due, in part, to the profound immunosuppressive microenvironment seen in GBMs, there has been a broad interest in immunotherapy. In both GBMs and other cancers, therapeutic vaccines have generally yielded limited efficacy, despite their theoretical basis. However, recent results from the DCVax-L trial provide some promise for vaccine therapy in GBMs. There is also the potential that future combination therapies with vaccines and adjuvant immunomodulating agents may greatly enhance antitumor immune responses. Clinicians must remain open to novel therapeutic strategies, such as vaccinations, and carefully await the results of ongoing and future trials. In this review of GBM management, the promise and challenges of immunotherapy with a focus on therapeutic vaccinations are discussed. Additionally, adjuvant therapies, logistical considerations, and future directions are discussed.

Immunotherapy approaches for adult glioma: knowledge gained from recent clinical trials

PURPOSE OF REVIEW

Summarize principles behind various immunotherapy approaches for high and low-grade glioma in the context of recently completed clinical trials and the new insights they provide.

RECENT FINDINGS

Despite the widespread success of therapies targeting the T-cell checkpoints programmed-death 1 and cytotoxic T lymphocyte antigen 4 in other malignancies, recent phase III trials in glioblastoma confirm the lack of efficacy of anti-programmed-death 1 monotherapy in more than 90% of patients. Vaccination approaches remain under investigation for high-grade glioma and have shown activity in some low-grade glioma patients. Chimeric antigen receptor T cells now feature a new generation of products engineered to potentially withstand glucocorticoid therapy. Oncolytic viral therapies have similarly advanced in sophistication, with drug-sensitive gene expression and tumor-selective modifications. Combinations of therapies hold promise for overcoming the numerous mechanisms of immune suppression in glioma.

SUMMARY

Although immunotherapies have yet to show rates of efficacy compared with other malignancies, new knowledge of immunology and combination therapies brings hope for improved efficacy in the future.

Size optimization of carfilzomib nanocrystals for systemic delivery to solid tumors

Carfilzomib (CFZ) is a second-generation proteasome inhibitor effective in blood cancer therapy. However, CFZ has shown limited efficacy in solid tumor therapy due to the short half-life and poor tumor distribution. Albumin-coated nanocrystal (NC) formulation was shown to improve the circulation stability of CFZ, but its antitumor efficacy remained suboptimal. We hypothesize that NC size reduction is critical to the formulation safety and efficacy as the small size would decrease the distribution in the reticuloendothelial system (RES) and selectively increase the uptake by tumor cells. We controlled the size of CFZ-NCs by varying the production parameters in the crystallization-in-medium method and compared the size-reduced CFZ-NCs (z-average of 168 nm, NC₁₆₈) with a larger counterpart (z-average of 325 nm, NC₃₂₅) as well as the commercial CFZ formulation (CFZ-CD). Both CFZ-NCs showed similar or higher cytotoxicity than CFZ-CD against breast cancer cells. NC₁₆₈ showed greater uptake by cancer cells, less uptake by macrophages and lower immune cell toxicity than NC₃₂₅ or CFZ-CD. NC₁₆₈, but not NC₃₂₅, showed a similar safety profile to CFZ-CD in vivo. The biodistribution and antitumor efficacy of CFZ-NCs in mice were also size-dependent. NC₁₆₈ showed greater antitumor efficacy and tumor accumulation but lower RES accumulation than NC₃₂₅ in 4T1 breast cancer model. These results support that NC formulation with an optimal particle size can improve the therapeutic efficacy of CFZ in solid tumors.

A novel oral metronomic chemotherapy provokes tumor specific immunity resulting in colon cancer eradication in combination with anti-PD-1 therapy

In this study, we investigated the immune-modulating effects of a novel metronomic chemotherapy (MCT) featuring combined oral oxaliplatin (OXA) and pemetrexed (PMX) for colon cancer. OXA and PMX were ionically complexed with lysine derivative of deoxycholic acid (DCK), and incorporated into nanoemulsions or colloidal dispersions, yielding OXA/DCK-NE and PMX/DCK-OP, respectively, to improve their oral bioavailabilities. MCT was not associated with significant lymphotoxicity whereas the maximum tolerated dose (MTD) afforded systemic immunosuppression. MCT was associated with more immunogenic cell death and tumor cell MHC-class I expression than was MTD. MCT improved the tumor antigen presentation of dendritic cells and increased the number of functional T cells in the tumor. MCT also helped to enhance antigen-specific memory responses both locally and systemically. By combining MCT with anti-programmed cell death protein-1 (αPD-1) therapy, the tumor volume was suppressed by 97.85 ± 84.88% compared to the control, resulting in a 95% complete response rate. Upon re-challenge, all tumor-free mice rejected secondary tumors, indicating the induction of a tumor specific memory response. Thus, MCT using an OXA and PMX combination, together with αPD-1, successfully treated colon cancer by activating both innate and adaptive immune cells and elicited tumor-specific long-term immune memory while avoiding toxicity caused by MTD treatment.

Dendritic Cells and Cancer Immunotherapy: The Adjuvant Effect

Dendritic cells (DCs) are immune specialized cells playing a critical role in promoting immune response against antigens, and may represent important targets for therapeutic interventions in cancer. DCs can be stimulated ex vivo with pro-inflammatory molecules and loaded with tumor-specific antigen(s). Protocols describing the specific details of DCs vaccination manufacturing vary widely, but regardless of the employed protocol, the DCs vaccination safety and its ability to induce antitumor responses is clearly established. Many years of studies have focused on the ability of DCs to provide overall survival benefits at least for a selection of cancer patients. Lessons learned from early trials lead to the hypothesis that, to improve the efficacy of DCs-based immunotherapy, this should be combined with other treatments. Thus, the vaccine’s ultimate role may lie in the combinatorial approaches of DCs-based immunotherapy with chemotherapy and radiotherapy, more than in monotherapy. In this review, we address some key questions regarding the integration of DCs vaccination with multimodality therapy approaches for cancer treatment paradigms.

Profiling of bacterial bloodstream infections in hematological and oncological patients based on a comparative survival analysis

Bloodstream infections (BSI) are a frequent complication in patients with hematological and oncological diseases. However, the impact of different bacterial species causing BSI and of multiple BSI remains incompletely understood. We performed a retrospective study profiling 637 bacterial BSI episodes in hematological and oncological patients. Based on the 30-day (30d) overall survival (OS), we analyzed different types of multiple BSI and grouped BSI-associated bacteria into clusters followed by further assessment of clinical and infection-related characteristics. We discovered that polymicrobial BSI (different organisms on the first day of a BSI episode) and sequential BSI (another BSI before the respective BSI episode) were associated with a worse 30d OS. Different bacterial groups could be classified into three BSI outcome clusters based on 30d OS: favorable (FAV) including mainly common skin contaminants, Escherichia spp. and Streptococcus spp.; intermediate (INT) including mainly Enterococcus spp., vancomycin-resistant Enterococcus spp., and multidrug-resistant gram-negative bacteria (MDRGN); and adverse (ADV) including MDRGN with an additional carbapenem-resistance (MDRGN+CR). A polymicrobial or sequential BSI especially influenced the outcome in the combination of two INT cluster BSI. The presence of a polymicrobial BSI and the assignment into the BSI outcome clusters were identified as independent risk factors for 30d mortality in a Cox multivariate regression analysis. The assignment to a BSI outcome cluster and the differentiated perspective of multiple BSI open new insights into the prognosis of patients with BSI and should be further validated in other patient cohorts.

Adult immuno-oncology: using past failures to inform the future

In oncology, "immunotherapy" is a broad term encompassing multiple means of utilizing the patient's immune system to combat malignancy. Prominent among these are immune checkpoint inhibitors, cellular therapies including chimeric antigen receptor T-cell therapy, vaccines, and oncolytic viruses. Immunotherapy for glioblastoma (GBM) has had mixed results in early trials. In this context, the past, present, and future of immune oncology for the treatment of GBM was discussed by clinical, research, and thought leaders as well as patient advocates at the first annual Remission Summit in 2019. The goal was to use current knowledge (published and unpublished) to identify possible causes of treatment failures and the best strategies to advance immunotherapy as a treatment modality for patients with GBM. The discussion focuses on past failures, current limitations, failure analyses, and proposed best practices moving forward.

Radiotherapy, Temozolomide, and Antiprogrammed Cell Death Protein 1 Treatments Modulate the Immune Microenvironment in Experimental High-Grade Glioma

BACKGROUND

The lack of immune synergy with conventional chemoradiation could explain the failure of checkpoint inhibitors in current clinical trials for high-grade gliomas (HGGs).

OBJECTIVE

To analyze the impact of radiotherapy (RT), Temozolomide (TMZ) and antiprogrammed cell death protein 1 (αPD1) (as single or combined treatments) on the immune microenvironment of experimental HGGs.

METHODS

Mice harboring neurosphere /CT-2A HGGs received RT (4 Gy, single dose), TMZ (50 mg/kg, 4 doses) and αPD1 (100 μg, 3 doses) as monotherapies or combinations. The influence on survival, tumor volume, and tumor-infiltrating immune cells was analyzed.

RESULTS

RT increased total T cells (P = .0159) and cluster of differentiation (CD)8+ T cells (P = .0078) compared to TMZ. Lymphocyte subpopulations resulting from TMZ or αPD1 treatment were comparable with those of controls. RT reduced M2 tumor-associated macrophages/microglia (P = .0019) and monocytic myeloid derived suppressor cells (mMDSCs, P = .0003) compared to controls. The effect on mMDSC was also seen following TMZ and αPD1 treatment, although less pronounced (P = .0439 and P = .0538, respectively). Combining RT with TMZ reduced CD8+ T cells (P = .0145) compared to RT alone. Adding αPD1 partially mitigated this effect as shown by the increased CD8+ T cells/Tregs ratio, even if this result failed to reach statistical significance (P = .0973). Changing the combination sequence of RT, TMZ, and αPD1 did not alter survival nor the immune effects.

CONCLUSION

RT, TMZ, and αPD1 modify the immune microenvironment of HGG. The combination of RT with TMZ induces a strong immune suppression which cannot be effectively counteracted by αPD1.

Impact of chemotherapy on lymphocytes and serological memory in recovered COVID-19 patients with acute leukemia

Chemotherapy is the major method of treatment for acute leukemia to date, while intensive chemotherapy may impair immunity. We previously reported that leukemia patients were more susceptible to COVID-19 than the overall population. However, for COVID-19 recovered patients with leukemia, the impacts of intensive chemotherapy on the immune memory of COVID-19 are unknown. This study characterized the changes in immune cells and SARS-CoV-2 antibodies in acute leukemia patients, who underwent chemotherapy after recovering from COVID-19. The study enrolled three groups of individuals. One group was a total of three acute leukemia patients, who recovered well from COVID-19 before the last cycle of chemotherapy. The other two groups were six COVID-19 recovered healthy people, and six normal uninfected healthy people, respectively. Levels of B cells, T cells, and NK cells in peripheral blood were analyzed by multiparameter flow cytometry. Besides, the SARS-CoV-2 antibodies were monitored. The results showed that B cells were severely decreased after chemotherapy, especially memory B cells. Most of the T cells and NK cells showed only minor changes after chemotherapy, except for γδ T cells. The serum levels of SARS-CoV-2 antibodies were not significantly affected after chemotherapy in two leukemia patients. However, interestingly, one leukemia patient's SARS-CoV-2 IgM showed dramatically increase, suggesting possible loss of serological memory after chemotherapy. These findings raised the concern for the stability of immune memory against SARS-CoV-2 during chemotherapy and the choice of anti-leukemia treatment in the COVID-19 pandemic.

Considerations when treating high-grade pediatric glioma patients with immunotherapy

INTRODUCTION

Children with high-grade gliomas (pHGGs) represent a clinical population in substantial need of new therapeutic options given the inefficacy and toxicity of current standard-of-care modalities. Although immunotherapy has emerged as a promising modality, it has yet to elicit a significant survival benefit for pHGG patients. While preclinical studies address a variety of underlying challenges, translational clinical trial design and management also need to reflect the most updated progress and lessons from the field.

AREAS COVERED

The authors will focus our discussion on the design of clinical trials, the management of potential toxicities, immune monitoring, and novel biomarkers. Clinical trial design should integrate appropriate patient populations, novel, and preclinically optimized trial design, and logical treatment combinations, particularly those which synergize with standard of care modalities. However, there are caveats due to the nature of immunotherapy trials, such as patient selection bias, evidenced by the frequent exclusion of patients on high-dose corticosteroids. Robust immune-modulating effects of modern immunotherapy can have toxicities. As such, it is important to understand and manage these, especially in pHGG patients.

EXPERT OPINION

Adequate integration of these considerations should allow us to effectively gain insights on biological activity, safety, and biomarkers associated with benefits for patients.

Polyamines drive myeloid cell survival by buffering intracellular pH to promote immunosuppression in glioblastoma

Glioblastoma is characterized by the robust infiltration of immunosuppressive tumor-associated myeloid cells (TAMCs). It is not fully understood how TAMCs survive in the acidic tumor microenvironment to cause immunosuppression in glioblastoma. Metabolic and RNA-seq analysis of TAMCs revealed that the arginine-ornithine-polyamine axis is up-regulated in glioblastoma TAMCs but not in tumor-infiltrating CD8+ T cells. Active de novo synthesis of highly basic polyamines within TAMCs efficiently buffered low intracellular pH to support the survival of these immunosuppressive cells in the harsh acidic environment of solid tumors. Administration of difluoromethylornithine (DFMO), a clinically approved inhibitor of polyamine generation, enhanced animal survival in immunocompetent mice by causing a tumor-specific reduction of polyamines and decreased intracellular pH in TAMCs. DFMO combination with immunotherapy or radiotherapy further enhanced animal survival. These findings indicate that polyamines are used by glioblastoma TAMCs to maintain normal intracellular pH and cell survival and thus promote immunosuppression during tumor evolution.

Phenotypic Screening of Chemical Libraries Enriched by Molecular Docking to Multiple Targets Selected from Glioblastoma Genomic Data

Like most solid tumors, glioblastoma multiforme (GBM) harbors multiple overexpressed and mutated genes that affect several signaling pathways. Suppressing tumor growth of solid tumors like GBM without toxicity may be achieved by small molecules that selectively modulate a collection of targets across different signaling pathways, also known as selective polypharmacology. Phenotypic screening can be an effective method to uncover such compounds, but the lack of approaches to create focused libraries tailored to tumor targets has limited its impact. Here, we create rational libraries for phenotypic screening by structure-based molecular docking chemical libraries to GBM-specific targets identified using the tumor's RNA sequence and mutation data along with cellular protein-protein interaction data. Screening this enriched library of 47 candidates led to several active compounds, including 1 (IPR-2025), which (i) inhibited cell viability of low-passage patient-derived GBM spheroids with single-digit micromolar IC50 values that are substantially better than standard-of-care temozolomide, (ii) blocked tube-formation of endothelial cells in Matrigel with submicromolar IC50 values, and (iii) had no effect on primary hematopoietic CD34+ progenitor spheroids or astrocyte cell viability. RNA sequencing provided the potential mechanism of action for 1, and mass spectrometry-based thermal proteome profiling confirmed that the compound engages multiple targets. The ability of 1 to inhibit GBM phenotypes without affecting normal cell viability suggests that our screening approach may hold promise for generating lead compounds with selective polypharmacology for the development of treatments of incurable diseases like GBM.

Impact of Radiochemotherapy on Immune Cell Subtypes in High-Grade Glioma Patients

Glioblastoma is a dreadful disease with very poor prognosis, median overall survival being <2 years despite standard-of-care treatment. This has led to the development of alternative strategies, among which immunotherapy is being actively tested. In particular, many clinical trials of therapeutic vaccination using peptides or tumor cells are ongoing. A major issue in implementing therapeutic vaccines in patients with high-grade glioma is that immune responses have to be elicited in the context of immunosuppressive treatments. Indeed, radiotherapy, chemotherapy, and steroids, which are part of the standard of care for patients with glioblastoma, are known to deplete leukocytes. Whether lymphopenia is beneficial or detrimental to elicitation of efficient immune responses is still debated. Here, in order to determine the impact of standard radiochemotherapy on immune cell subsets, we analyzed the phenotype and function of immune populations in 25 patients with high-grade glioma along concomitant radiochemotherapy and adjuvant chemotherapy with temozolomide. Thirteen healthy individuals were studied along the same period. We show that absolute T and B cell counts are reduced upon concomitant radiochemotherapy. Importantly, T cell counts were not restored long-term after discontinuation of treatment. In addition, the percentage of T regulatory cells among CD4 T cells was increased during the same period and was not decreased upon treatment discontinuation. Finally, we show that the ability of T cells to proliferate is transiently reduced after concomitant radiochemotherapy but is restored at the time of adjuvant TMZ cycles. Although not experimentally validated, transient reduction in proliferation associated with strong lymphopenia during radiochemotherapy may suggest that vaccine-induced T cell stimulation would be suboptimal in that period and that therapeutic vaccination should be performed outside radiochemotherapy administration. In addition, strategies aiming at depleting Treg cells should be implemented in future trials.

High leukemia-free survival after TBI-based conditioning and mycophenolate mofetil-containing immunosuppression in patients allografted for chronic myelomonocytic leukemia: a single-center experience

This retrospective single-center analysis studied the impact of the conditioning and the graft-versus-host disease (GVHD) prophylaxis on outcome in unselected patients allografted for chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia (AML) secondary to documented prior CMML. A total of 44 patients (median age 61 years) allografted between 2002 and 2019 in our institution were analyzed. Fifteen patients had secondary AML. The conditioning regimen was fractionated 6-8 Gy total body irradiation (TBI) in combination with fludarabine in 33 (75%) patients. Eleven patients (25%) received alkylator-based conditioning therapy without TBI. For GVHD prophylaxis, a calcineurin inhibitor (CNI) backbone in combination with methotrexate (MTX) or mycophenolate mofetil (MMF) was applied in 21 and 23 patients, respectively. All patients allografted from an unrelated donor (UD) received antithymocyte globuline. In univariate analysis of the entire cohort, TBI-based conditioning and MMF-containing immunosuppression were associated with improved leukemia-free survival (LFS, HR 0.16, P < 0.001 and HR 0.41, P = 0.030, respectively). After stratification according to conditioning and GVHD prophylaxis into four groups (TBI-MMF [n = 17], TBI-MTX [n = 16], alkylator-MMF [n = 6], alkylator-MTX [n = 5]), TBI-MMF was associated with improved overall survival (OS) and LFS (P = 0.001 and P < 0.001, respectively). Patient and disease characteristics did not differ between the groups. The associations of TBI-based conditioning and MMF with prolonged LFS were observed across the CMML (n = 29), secondary AML (n = 15), and UD allograft (n = 34) subgroups. In summary, our study suggests that allografting based on intermediate-dose TBI conditioning and MMF-containing GVHD prophylaxis is associated with increased disease control in CMML. Larger (registry-based) studies are warranted to confirm our findings.

Sustained Delivery of Carfilzomib by Tannic Acid-Based Nanocapsules Helps Develop Antitumor Immunity

A group of chemotherapeutic drugs has gained increasing interest in cancer immunotherapy due to the potential to induce immunogenic cell death (ICD). A critical challenge in using the ICD inducers in cancer immunotherapy is the immunotoxicity accompanying their antiproliferative effects. To alleviate this, a nanocapsule formulation of carfilzomib (CFZ), an ICD-inducing proteasome inhibitor, was developed using interfacial supramolecular assembly of tannic acid (TA) and iron, supplemented with albumin coating. The albumin-coated CFZ nanocapsules (CFZ-pTA-alb) attenuated CFZ release, reducing toxicity to immune cells. Moreover, due to the adhesive nature of the TA assembly, CFZ-pTA-alb served as a reservoir of damage-associated molecular patterns released from dying tumor cells to activate dendritic cells. Upon intratumoral administration, CFZ-pTA-alb prolonged tumor retention of CFZ and showed consistently greater antitumor effects than cyclodextrin-solubilized CFZ (CFZ-CD) in B16F10 and CT26 tumor models. Unlike CFZ-CD, the locally injected CFZ-pTA-alb protected or enhanced CD8+ T cell population in tumors, helped develop splenocytes with tumor-specific interferon-γ response, and delayed tumor development on the contralateral side in immunocompetent mice (but not in athymic nude mice), supporting that CFZ-pTA-alb contributed to activating antitumor immunity. This study demonstrates that sustained delivery of ICD inducers by TA-based nanocapsules is an effective way of translating local ICD induction to systemic antitumor immunity.

Temozolomide for immunomodulation in the treatment of glioblastoma

Temozolomide is the most widely used chemotherapy for patients with glioblastoma (GBM) despite the fact that approximately half of treated patients have temozolomide resistance and all patients eventually fail therapy. Due to the limited efficacy of existing therapies, immunotherapy is being widely investigated for patients with GBM. However, initial immunotherapy trials in GBM patients have had disappointing results as monotherapy. Therefore, combinatorial treatment strategies are being investigated. Temozolomide has several effects on the immune system that are dependent on mode of delivery and the dosing strategy, which may have unpredicted effects on immunotherapy. Here we summarize the immune modulating role of temozolomide alone and in combination with immunotherapies such as dendritic cell vaccines, T-cell therapy, and immune checkpoint inhibitors for patients with GBM.

Expansion of effector and memory T cells is associated with increased survival in recurrent glioblastomas treated with dendritic cell immunotherapy

Background

The efficacy of dendritic cell (DC) immunotherapy as a single therapeutic modality for the treatment of glioblastoma (GBM) patients remains limited. In this study, we evaluated in patients with GBM recurrence the immune-mediated effects of DC loaded with autologous tumor lysate combined with temozolomide (TMZ) or tetanus toxoid (TT).

Methods

In the phase I-II clinical study DENDR2, 12 patients were treated with 5 DC vaccinations combined with dose-dense TMZ. Subsequently, in eight patients, here defined as Variant (V)-DENDR2, the vaccine site was preconditioned with TT 24 hours before DC vaccination and TMZ was avoided. As a survival endpoint for these studies, we considered overall survival 9 months (OS9) after second surgery. Patients were analyzed for the generation of effector, memory, and T helper immune response.

Results

Four of 12 DENDR2 patients reached OS9, but all failed to show an immunological response. Five of eight V-DENDR2 patients (62%) reached OS9, and one patient is still alive (OS >30 months). A robust CD8⁺ T-cell activation and memory T-cell formation were observed in V-DENDR2 OS>9. Only in these patients, the vaccine-specific CD4⁺ T-cell activation (CD38⁺/HLA-DR⁺) was paralleled by an increase in TT-induced CD4⁺/CD38^low/CD127^high memory T cells. Only V-DENDR2 patients showed the formation of a nodule at the DC injection site infiltrated by CCL3-expressing CD4⁺ T cells.

Conclusions

TT preconditioning of the vaccine site and lack of TMZ could contribute to the efficacy of DC immunotherapy by inducing an effector response, memory, and helper T-cell generation.

Reduced Neoantigen Expression Revealed by Longitudinal Multiomics as a Possible Immune Evasion Mechanism in Glioma

Immune-based therapies have shown limited efficacy in glioma thus far. This might be at least in part due to insufficient numbers of neoantigens, thought to be targets of immune attack. In addition, we hypothesized that dynamic genetic and epigenetic tumor evolution in gliomas might also affect the mutation/neoantigen landscape and contribute to treatment resistance through immune evasion. Here, we investigated changes in the neoantigen landscape and immunologic features during glioma progression using exome and RNA-seq of paired primary and recurrent tumor samples obtained from 25 WHO grade II-IV glioma patients (glioblastoma, IDH-wild-type, n = 8; grade II-III astrocytoma, IDH-mutant, n = 9; and grade II-III oligodendroglioma, IDH-mutant, 1p/19q-codeleted, n = 8). The number of missense mutations, predicted neoantigens, or expressed neoantigens was not significantly different between primary and recurrent tumors. However, we found that in individual patients the ratio of expressed neoantigens to predicted neoantigens, designated the "neoantigen expression ratio," decreased significantly at recurrence (P = 0.003). This phenomenon was particularly pronounced for "high-affinity," "clonal," and "passenger gene-derived" neoantigens. Gene expression and IHC analyses suggested that the decreased neoantigen expression ratio was associated with intact antigen presentation machinery, increased tumor-infiltrating immune cells, and ongoing immune responses. Our findings imply that decreased expression of highly immunogenic neoantigens, possibly due to persistent immune selection pressure, might be one of the immune evasion mechanisms along with tumor clonal evolution in some gliomas.

Promising vaccines for treating glioblastoma

INTRODUCTION

Conventional therapies for glioblastoma  (GBM) typically fail to provide lasting antitumor benefits, owing to their inability to specifically eliminate all malignant cells. Cancer vaccines are currently being evaluated as a means to direct the adaptive immune system to target residual GBM cells that remain following standard-of-care treatment.

AREAS COVERED

In this review, we provide an overview of the more noteworthy cancer vaccines that are under investigation for the treatment of GBM, as well as potential future directions that may enhance GBM-vaccine effectiveness.

EXPERT OPINION

To date, no cancer vaccines have been proven effective against GBM; however, only a few have reached phase III clinical testing. Clinical immunological monitoring data suggest that GBM vaccines are capable of stimulating immune responses reactive to GBM antigens, but whether these responses have an appreciable antitumor effect on GBM is still uncertain. Nevertheless, there have been several promising outcomes in early phase clinical trials, which lend encouragement to this area of study. Further studies with GBM vaccines are, therefore, warranted.

Bloodstream infections in oncology patients at Red Cross War Memorial Children's Hospital, Cape Town, from 2012 to 2014

OBJECTIVES

This study was performed to investigate the epidemiology of bloodstream infection (BSI) in oncology patients at Red Cross War Memorial Children's Hospital (RCWMCH), Cape Town, with focus placed on the most common causes, complications, and antimicrobial susceptibilities in BSI.

METHODS

A retrospective cross-sectional study was conducted in the Haematology-Oncology Unit of RCWMCH. All positive blood cultures from RCWMCH oncology patients obtained in 2012 to 2014 were retrieved to identify cases of BSI.

RESULTS

Three hundred and forty-three positive cultures were identified, for 150 BSI episodes among 89 patients; 49.1% of the culture isolates were Gram-positive bacteria, 41.6% were Gram-negative bacteria, and 9.3% were fungal. Coagulase-negative Staphylococcus and viridans group Streptococcus were the most common Gram-positive isolates. Escherichia coli and Klebsiella species were the most common Gram-negative isolates. The majority of BSI episodes occurred in patients with haematological malignancies (74%), in the presence of severe neutropenia (76.4%), and were associated with chemotherapy (88%). Complications occurred in 14% of BSI. Fungal infections had the highest prevalence of complications (21.4%). Three children died during BSI, giving a case-fatality rate of 2%.

CONCLUSIONS

BSI in these patients was caused mainly by Gram-positive bacteria and was associated with a low case-fatality rate. These results are consistent with worldwide experience of BSI in paediatric oncology.

Determining the sequence of novel therapies in the treatment of relapsed Hodgkin's lymphoma

INTRODUCTION

Hodgkin's lymphoma (HL) accounts for about 10% of all lymphomas in the U.S.A. Exceptional progress has been made in the treatment of HL with complete response (CR) rates up to 94% in limited stage and 88% in advanced stage disease with regimens such as adriamycin, bleomycin, vinblastine, and dacarbazine in the frontline setting. Nevertheless, up to 10% of patients with limited stage disease and 20-30% of those with advanced stage HL relapse. In the last decade, newer agents such as brentuximab vedotin (BV) and checkpoint inhibitors have been approved by the FDA for treatment of patients with relapsed or refractory HL. As these newer agents are increasingly incorporated in both the frontline and relapsed settings, their optimal sequence becomes challenging for clinicians. Areas covered: This review will discuss the evidence behind the approval of BV and checkpoint inhibitors in HL and the appropriate sequence for using them in relapsed HL. Expert commentary: The appropriate sequence of BV and/or checkpoint inhibitors in the relapsed setting depends on the regimen used in the frontline setting.

Survival gain in glioblastoma patients treated with dendritic cell immunotherapy is associated with increased NK but not CD8+ T cell activation in the presence of adjuvant temozolomide

In a two-stage phase II study, 24 patients with first diagnosis of glioblastoma (GBM) were treated with dendritic cell (DC) immunotherapy associated to standard radiochemotherapy with temozolomide (TMZ) followed by adjuvant TMZ.

Three intradermal injections of mature DC loaded with autologous GBM lysate were administered before adjuvant TMZ, while 4 injections were performed during adjuvant TMZ. According to a two-stage Simon design, to proceed to the second stage progression-free survival (PFS) 12 months after surgery was expected in at least 8 cases enrolled in the first stage. Evidence of immune response and interaction with chemotherapy were investigated. After a median follow up of 17.4 months, 9 patients reached PFS12. In these patients (responders, 37.5%), DC vaccination induced a significant, persistent activation of NK cells, whose increased response was significantly associated with prolonged survival. CD8⁺ T cells underwent rapid expansion and priming but, after the first administration of adjuvant TMZ, failed to generate a memory status. Resistance to TMZ was associated with robust expression of the multidrug resistance protein ABCC3 in NK but not CD8⁺ T cells. The negative effect of TMZ on the formation of T cell-associated antitumor memory deserves consideration in future clinical trials including immunotherapy.

Anti-PD-1 antitumor immunity is enhanced by local and abrogated by systemic chemotherapy in GBM

The immunosuppressive effects of chemotherapy present a challenge for designing effective cancer immunotherapy strategies. We hypothesized that although systemic chemotherapy (SC) exhibits negative immunologic effects, local chemotherapy (LC) can potentiate an antitumor immune response. We show that LC combined with anti-programmed cell death protein 1 (PD-1) facilitates an antitumor immune response and improves survival (P < 0.001) in glioblastoma. LC-treated mice had increased infiltration of tumor-associated dendritic cells and clonal expansion of antigen-specific T effector cells. In comparison, SC resulted in systemic and intratumoral lymphodepletion, with decreased immune memory in long-term survivors. Furthermore, adoptive transfer of CD8⁺ cells from LC-treated mice partially rescued SC-treated mice after tumor rechallenge. Last, the timing of chemo- and immunotherapy had differential effects on anti-PD-1 efficacy. This study suggests that both mode of delivery and timing have distinct effects on the efficacy of anti-PD-1. The results of this work could help guide the selection and scheduling of combination treatment for patients with glioblastoma and other tumor types.

A review of immune therapy in cancer and a question: can thermal therapy increase tumor response?

Immune therapy is a successful cancer treatment coming into its own. This is because checkpoint molecules, adoptive specific lymphocyte transfer and chimeric antigen T-cell (CAR-T) therapy are able to induce more durable responses in an increasing number of malignancies compared to chemotherapy. In addition, immune therapies are able to treat bulky disease, whereas standard cytotoxic therapies cannot treat large tumour burdens. Checkpoint inhibitor monoclonal antibodies are becoming widely used in the clinic and although more complex, adoptive lymphocyte transfer and CAR-T therapies show promise. We are learning that there are nuances to predicting the successful use of the checkpoint inhibitors as well as to specific-antigen adoptive and CAR-T therapies. We are also newly aware of a here-to-fore unrealised natural force, the status of the microbiome. However, despite better understanding of mechanisms of action of the new immune therapies, the best responses to the new immune therapies remain 20-30%. Likely the best way to improve this somewhat low response rate for patients is to increase the patient's own immune response. Thermal therapy is a way to do this. All forms of thermal therapy, from fever-range systemic thermal therapy, to high-temperature HIFU and even cryotherapy improve the immune response pre-clinically. It is time to test the immune therapies with thermal therapy in vivo to test for optimal timing of the combinations that will best enhance tumour response and then to begin to test the immune therapies with thermal therapy in the clinic as soon as possible.

Immunotherapy with subcutaneous immunogenic autologous tumor lysate increases murine glioblastoma survival

Immunotherapeutic strategies for glioblastoma, the most frequent malignant primary brain tumor, aim to improve its disastrous consequences. On top of the standard treatment, one strategy uses T cell activation by autologous dendritic cells (DC) ex vivo loaded with tumor lysate to attack remaining cancer cells. Wondering whether 'targeting' in vivo DCs could replace these ex vivo ones, immunogenic autologous tumor lysate was used to treat glioma-inoculated mice in the absence of ex vivo loaded DCs. Potential immune mechanisms were studied in two orthotopic, immunocompetent murine glioma models. Pre-tumoral subcutaneous lysate treatment resulted in a survival benefit comparable to subcutaneous DC therapy. Focussing on the immune response, glioma T cell infiltration was observed in parallel with decreased amounts of regulatory T cells. Moreover, these results were accompanied by the presence of strong tumor-specific immunological memory, shown by complete survival of a second glioblastoma tumor, inoculated 100 days after the first one. Finally, in combination with temozolomide, survival of established glioma in mice could be increased. Our results show the potential of immunogenic autologous tumor lysate used to treat murine glioblastoma, which will be worthwhile to study in clinical trials as it has potential as a cost-efficient adjuvant treatment strategy for gliomas.

Temozolomide low-dose chemotherapy in newly diagnosed low-grade gliomas: activity, safety, and long-term follow-up

PURPOSE

To explore the efficacy and toxicity of an extended schedule of temozolomide (50 mg/mq 1 week on/1 week off) in a population of newly diagnosed low-grade gliomas (LGG).

METHODS

Primary endpoints were progression-free survival (PFS) at 12 and 24 months and response rate evaluated with Response Assessment in Neuro-Oncology Criteria. Secondary endpoints were clinical benefit (reduction of seizures frequency), reduction of steroid, and modifications of Karnofsky Performance Status.

RESULTS

From 2006 to 2009, we enrolled 14 consecutive patients with newly diagnosed LGG: 8 grade II astrocytomas, 2 oligodendroglioma, and 4 oligo-astrocytoma. Temozolomide was administered for 18 cycles (mean) per patient (range 3-24 cycles). In 57.5% (n = 8), we observed stable disease, 28.5% (n = 4) presented a minor response, and 14% (n = 2) showed progression. Five patients presented early progression during the first year of treatment and the study was stopped. A relevant clinical benefit was observed in 85% of patients (seizure control). After 6 years of follow-up, only 4 patients died. Prolonged PFS was associated with 1p-19q codeletion over 1p-19q intact (35 vs 4 months; p<0.04) and IDH1 mutation over IDH1 wild-type (36 vs 6 months; p<0.009).

CONCLUSIONS

The study was interrupted for the high rate of progression observed in the first 14 patients enrolled. However, our results show that an extended low dose of temozolomide presents interesting activity with objective response and clinical benefit, but does not seem to prevent progression in patients presenting unfavorable molecular prognostic factors.

Repeated cycles of 5-fluorouracil chemotherapy impaired anti-tumor functions of cytotoxic T cells in a CT26 tumor-bearing mouse model

Background

Recently, the immunostimulatory roles of chemotherapeutics have been increasingly revealed, although bone marrow suppression is still a common toxicity of chemotherapy. While the numbers and ratios of different immune subpopulations are analyzed after chemotherapy, changes to immune status after each cycle of treatment are less studied and remain unclear.

Results

To determine the tumor-specific immune status and functions after different cycles of chemotherapy, we treated CT26 tumor-bearing mice with one to four cycles of 5-fluorouracil (5-FU). Overall survival was not improved when more than one cycle of 5-FU was administered. Here we present data concerning the immune statuses after one and three cycles of chemotherapy. We analyzed the amount of spleen cells from mice treated with one and three cycles of 5-FU as well as assayed their proliferation and cytotoxicity against the CT26 tumor cell line. We found that the absolute numbers of CD8 T-cells and NK cells were not influenced significantly after either one or three cycles of chemotherapy. However, after three cycles of 5-FU, proliferated CD8 T-cells were decreased, and CT26-specific cytotoxicity and IFN-γ secretion of spleen cells were impaired in vitro. After one cycle of 5-FU, there was a greater percentage of tumor infiltrating CD8 T-cells. In addition, more proliferated CD8 T-cells, enhanced tumor-specific cytotoxicity as well as IFN-γ secretion of spleen cells against CT26 in vitro were observed. Given the increased expression of immunosuppressive factors, such as PD-L1 and TGF-β, we assessed the effect of early introduction of immunotherapy in combination with chemotherapy. We found that mice treated with cytokine induced killer cells and PD-L1 monoclonal antibodies after one cycle of 5-FU had a better anti-tumor performance than those treated with chemotherapy or immunotherapy alone.

Conclusions

These data suggest that a single cycle of 5-FU treatment promoted an anti-tumor immune response, whereas repeated chemotherapy cycles impaired anti-tumor immune functions. Though the amount of immune cells could recover after chemotherapy suspension, their anti-tumor functions were damaged by multiple rounds of chemotherapy. These findings also point towards early implementation of immunotherapy to improve the anti-tumor effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-016-0167-7) contains supplementary material, which is available to authorized users.

Immunological effects of chemotherapy and radiotherapy against brain tumors

INTRODUCTION

The mainstays of brain tumor therapy are surgery, radiotherapy and chemotherapy. Cancer immunotherapy is explored as an additional treatment modality. However, emerging evidence indicates that also radio- and chemotherapy have immunological effects in addition to their cytotoxic and cytostatic activities.

AREA COVERED

We summarize the literature on radio- and chemotherapy-mediated immunological effects in primary and secondary brain tumors and outline open questions within the field. To this end, a literature search was performed using the terms 'brain tumor', 'immune system', 'immunogenic cell death', 'vaccination', 'checkpoint inhibition', 'radiotherapy', 'chemotherapy' and derivations thereof. Expert commentary: Immunological effects of chemo- and radiotherapy in brain tumors involve direct immunogenic modulations of tumor cells, changes of the microenvironment and functional alterations of innate and adaptive immune cells. Each treatment modality can exert various effects that comprise both immune-stimulatory and immunosuppressive mechanisms. A detailed knowledge of these mechanisms is indispensable for an optimal combination of conventional anti-tumor treatments and novel immunotherapeutic approaches.

Unlocking the promise of oncolytic virotherapy in glioma: combination with chemotherapy to enhance efficacy

Malignant glioma is a relentless burden to both patients and clinicians, and calls for innovation to overcome the limitations in current management. Glioma therapy using viruses has been investigated to accentuate the nature of a virus, killing a host tumor cell during its replication. As virus mediated approaches progress with promising therapeutic advantages, combination therapy with chemotherapy and oncolytic viruses has emerged as a more synergistic and possibly efficacious therapy. Here, we will review malignant glioma as well as prior experience with oncolytic viruses, chemotherapy and combination of the two, examining how the combination can be optimized in the future.

Cellular immunotherapy for malignant gliomas

INTRODUCTION

Cancer immunotherapy has made much progress in recent years. Clinical trials evaluating a variety of immunotherapeutic approaches are underway in patients with malignant gliomas. Thanks to recent advancements in cell engineering technologies, infusion of ex vivo prepared immune cells have emerged as promising strategies of cancer immunotherapy.

AREAS COVERED

Herein, the authors review recent and current studies using cellular immunotherapies for malignant gliomas. Specifically, they cover the following areas: a) cellular vaccine approaches using tumor cell-based or dendritic cell (DC)-based vaccines, and b) adoptive cell transfer (ACT) approaches, including lymphokine-activated killer (LAK) cells, γδ T cells, tumor-infiltrating lymphocytes (TIL), chimeric antigen receptor (CAR)-T cells and T-cell receptor (TCR) transduced T cells.

EXPERT OPINION

While some of the recent studies have shown promising results, the ultimate success of cellular immunotherapy in brain tumor patients would require improvements in the following areas: 1) feasibility in producing cellular therapeutics; 2) identification and characterization of targetable antigens given the paucity and heterogeneity of tumor specific antigens; 3) the development of strategies to promote effector T-cell trafficking; 4) overcoming local and systemic immune suppression, and 5) proper interpretation of imaging data for brain tumor patients receiving immunotherapy.

Response rates and durability of chemotherapy among 62 patients with metastatic Merkel cell carcinoma

Cytotoxic chemotherapy is commonly used to treat advanced Merkel cell carcinoma (MCC). However, its efficacy in distant metastatic MCC patients is unclear, in part because most prior reports aggregated these patients with those receiving adjuvant chemotherapy and combined chemoradiation for whom prognosis and outcomes may differ. In this retrospective study, we analyzed detailed records from 62 patients with distant metastatic MCC treated with cytotoxic chemotherapy. Efficacy outcomes including response rate (RR), durability of response (DOR), progression‐free survival (PFS), and overall survival (OS) were evaluated. In this cohort, platinum plus etoposide was the most commonly used first‐line regimen (69%). RR to first‐line chemotherapy was 55% (34/62) with complete responses (CR) in 13% (8/62) and partial responses (PR) in 42% (26/62) while 6% (4/62) had stable disease and 39% (24/62) had progressive disease. Median PFS was 94 days and median OS was 9.5 months from start of chemotherapy. Among responding patients (n = 34), median PFS was 168 days and median DOR was 85 days. Among 30 of the 62 patients who received second‐line chemotherapy, RR was 23% (7/30; 1 CR, 6 PR), median PFS was 61 days, and median DOR was 101 days. In summary, first‐line chemotherapy is associated with a high RR in metastatic MCC, but responses are typically not durable, and the median PFS is only 3 months. These results suggest rapid emergence of chemoresistance in MCC tumors, and may serve as a useful comparator for immunotherapies currently being explored for metastatic MCC.

The multidrug-resistance transporter Abcc3 protects NK cells from chemotherapy in a murine model of malignant glioma

Abcc3, a member of the ATP-binding cassette transporter superfamily, plays a role in multidrug resistance. Here, we found that Abcc3 is highly expressed in blood-derived NK cells but not in CD8(+) T cells. In GL261 glioma-bearing mice treated with the alkylating agent temozolomide (TMZ) for 5 d, an early increased frequency of NK cells was observed. We also found that Abcc3 is strongly upregulated and functionally active in NK cells from mice treated with TMZ compared to controls. We demonstrate that Abcc3 is critical for NK cell survival during TMZ administration; more importantly, Akt, involved in lymphocyte survival, is phosphorylated only in NK cells expressing Abcc3. The resistance of NK cells to chemotherapy was accompanied by increased migration and homing in the brain at early time points. Cytotoxicity, evaluated by IFNγ production and specific lytic activity against GL261 cells, increased peripherally in the later phases, after conclusion of TMZ treatment. Intra-tumor increase of the NK effector subset as well as in IFNγ, granzymes and perforin-1 expression, were found early and persisted over time, correlating with a profound modulation on glioma microenvironment induced by TMZ. Our findings reveal an important involvement of Abcc3 in NK cell resistance to chemotherapy and have important clinical implications for patients treated with chemo-immunotherapy.

How Chemotherapy Increases the Risk of Systemic Candidiasis in Cancer Patients: Current Paradigm and Future Directions

Candida albicans is a fungal commensal and a major colonizer of the human skin, as well as of the gastrointestinal and genitourinary tracts. It is also one of the leading causes of opportunistic microbial infections in cancer patients, often presenting in a life-threatening, systemic form. Increased susceptibility to such infections in cancer patients is attributed primarily to chemotherapy-induced depression of innate immune cells and weakened epithelial barriers, which are the body’s first-line defenses against fungal infections. Moreover, classical chemotherapeutic agents also have a detrimental effect on components of the adaptive immune system, which further play important roles in the antifungal response. In this review, we discuss the current paradigm regarding the mechanisms behind the increased risk of systemic candidiasis in cancer patients. We also highlight some recent findings, which suggest that chemotherapy may have more extensive effects beyond the human host, in particular towards C. albicans itself and the bacterial microbiota. The extent to which these additional effects contribute towards the development of candidiasis in chemotherapy-treated patients remains to be investigated.

Combinatorial prospects of nano-targeted chemoimmunotherapy

Despite the significant increase in our knowledge on cancer initiation and progression, and the development of novel cancer treatments, overall patient survival rates have thus far only marginally improved. However, it can be expected that lasting tumor control will be attainable for an increasing number of cancer patients in the foreseeable future, which is likely to be achieved by combining cancer chemotherapy with anticancer immunotherapy. A plethora of new cancer chemotherapy reagents are expected to become accessible to the clinic in the coming years which can then be used for efficient tumor debulking and aid in antigen exposure to the immune system. Durable remission and the eradication of micrometastases are likely to be achieved with specialized monoclonal antibodies and therapeutic cancer vaccines that modulate the immune system to overcome immunosuppression and kill distant cancer cells. Moreover, the method of drug delivery to tumors, stromal and immune cells is expected to shift largely from conventional 'free' drug molecules to encapsulated in targeted nano-vehicles, therapeutics often referred to or considered part of "nanomedicine". Several biocompatible nano-vehicles, such as metal-nanoparticles, biodegradable-nanoparticles, liposomes or dendrimers are potential candidates for targeted drug delivery but may also serve additional purposes. A dexterous combination of nanomedicine, cancer immunotherapy and chemotherapeutic engineering are likely to become the basis for new hope in the form of targeted cancer therapies that could attack tumors early in their development. One can envision nano-vehicles that would selectively deliver effective doses of chemotherapeutic agents to cancer cells while leaving healthy cells untouched. Furthermore, given that after chemotherapeutic treatment there often remains a limited number of chemo-resistant tumor cells, which go on to drive tumor progression, nano-vehicles could also be engineered to provoke an appropriate immune response to destroy these cells. Here, we discuss the potential of the combinatorial role of cancer chemotherapy, cancer immunotherapy and the prospective of nanotechnology for the targeted delivery of chemoimmunotherapeutic agents.

Biological evaluation of PEG modified nanosuspensions based on human serum albumin for tumor targeted delivery of paclitaxel

Since its approval by the FDA, Abraxane™ has been established as a clinical standard of paclitaxel (PTX)-based therapy against a variety of cancers. Despite success, Abraxane™ is still limited by suboptimal biodistribution, unfavorable pharmacokinetics and chronic toxicities from chloroform used during preparation. Accordingly, a PTX-loaded nanosuspension based on human serum albumin (HSA) with PEG modifiers (PTX-PEG-HSA) has been developed to optimize the in-vivo biodistribution, pharmacokinetics and safety of PTX over traditional PTX-HSA nanosuspensions prepared using the accepted method for Abraxane™. Results of in-vivo pharmacokinetic (PK) studies indicated PTX-PEG-HSA achieved prolonged blood circulation, illustrated by an 8.8-fold and 4.8-fold increase in area-under-the-curve (AUC) of PTX over Taxol® and PTX-HSA, while the mean residence time (MRT) of PTX in PTX-PEG-HSA was increased by 3.2-fold and 1.5-fold, respectively. HSA mediated active targeting further suppressed non-specific distribution of PTX to normal tissues, which permitted enhanced antitumor efficacy in S180 mice over Taxol® and PTX-HSA. Safety of intravenously administered PTX-PEG-HSA was confirmed through lower hemolytic activity, a 2.2-fold and 1.2-fold increase in LD50 (113.4 mg/kg) over Taxol® and PTX-HSA alongside the absence of local venous irritation. Studies herein suggest the therapeutic and clinical applicability of PTX-PEG-HSA for tumor specific therapy.

CpG-1826 immunotherapy potentiates chemotherapeutic and anti-tumor immune responses to metronomic cyclophosphamide in a preclinical glioma model

Cyclophosphamide administered on an intermittent metronomic schedule induces strong immune-dependent regression in several glioma models. Here we investigate whether this immunogenic chemotherapy can be potentiated by combination with the immune stimulatory TLR9 agonist CpG-1826. CpG-1826 treatment of GL261 gliomas implanted in immune competent mice induced tumor growth delay associated with increased tumor recruitment of macrophages and B cells. Anti-tumor responses varied between individuals, with CpG-1826 inducing robust tumor growth delay in ~50% of treated mice. Both high and low CpG-1826-responsive mice showed striking improvements when CpG-1826 was combined with cyclophosphamide treatment. Tumor-associated macrophages, B cells, dendritic cells, and cytotoxic T cells were increased, T regulatory cells were not induced, and long-term GL261 glioma regression with immune memory was achieved when CpG-1826 was combined with either single cyclophosphamide dosing (90 mg/kg) or metronomic cyclophosphamide treatment (two cycles at 45 mg/kg, spaced 12-days apart). B16F10 melanoma, a low immunogenic tumor model, also showed enhanced immune and anti-tumor responses to cyclophosphamide/CpG-1826 chemoimmunotherapy, but unlike GL261 tumors, did not regress. TLR9-based immunotherapy can thus be effectively combined with immunogenic cyclophosphamide treatment to enhance immune-based anti-tumor responses, even in poorly immunogenic cancer models.

Modulation of APC Function and Anti-Tumor Immunity by Anti-Cancer Drugs

Professional antigen-presenting cells (APCs), such as dendritic cells (DCs), are central to the initiation and regulation of anti-cancer immunity. However, in the immunosuppressive environment within a tumor APCs may antagonize anti-tumor immunity by inducing regulatory T cells (Tregs) or anergy of effector T cells due to lack of efficient costimulation. Hence, in an optimal setting, anti-cancer drugs have the power to reduce tumor size and thereby may induce the release of tumor antigens and, at the same time, modulate APC function toward efficient priming of antigen-specific effector T cells. Selected cytotoxic agents may revert APC dysfunction either by directly maturing DCs or through induction of immunogenic tumor cell death. Furthermore, specific cytotoxic agents may support adaptive immunity by selectively depleting regulatory subsets, such as Tregs or myeloid-derived suppressor cells. Perspectively, this will allow developing effective combination strategies with novel immunotherapies to exert complementary pressure on tumors via direct toxicity as well as immune activation. We, here, review our current knowledge on the capacity of anti-cancer drugs to modulate APC functions to promote durable anti-cancer immune responses.

T-cell subsets in peripheral blood and tumors of patients treated with oncolytic adenoviruses

The quality of the antitumor immune response is decisive when developing new immunotherapies for cancer. Oncolytic adenoviruses cause a potent immunogenic stimulus and arming them with costimulatory molecules reshapes the immune response further. We evaluated peripheral blood T-cell subsets of 50 patients with refractory solid tumors undergoing treatment with oncolytic adenovirus. These data were compared to changes in antiviral and antitumor T cells, treatment efficacy, overall survival, and T-cell subsets in pre- and post-treatment tumor biopsies. Treatment caused a significant (P < 0.0001) shift in T-cell subsets in blood, characterized by a proportional increase of CD8(+) cells, and decrease of CD4(+) cells. Concomitant treatment with cyclophosphamide and temozolomide resulted in less CD4(+) decrease (P = 0.041) than cyclophosphamide only. Interestingly, we saw a correlation between T-cell changes in peripheral blood and the tumor site. This correlation was positive for CD8(+) and inverse for CD4(+) cells. These findings give insight to the interconnections between peripheral blood and tumor-infiltrating lymphocyte (TIL) populations regarding oncolytic virotherapy. In particular, our data suggest that induction of T-cell response is not sufficient for clinical response in the context of immunosuppressive tumors, and that peripheral blood T cells have a complicated and potentially misleading relationship with TILs.

Effective Treatment of Established GL261 Murine Gliomas through Picornavirus Vaccination-Enhanced Tumor Antigen-Specific CD8+ T Cell Responses

Glioblastoma (GBM) is among the most invasive and lethal of cancers, frequently infiltrating surrounding healthy tissue and giving rise to rapid recurrence. It is therefore critical to establish experimental model systems and develop therapeutic approaches that enhance anti-tumor immunity. In the current study, we have employed a newly developed murine glioma model to assess the efficacy of a novel picornavirus vaccination approach for the treatment of established tumors. The GL261-Quad system is a variation of the GL261 syngeneic glioma that has been engineered to expresses model T cell epitopes including OVA257-264. MRI revealed that both GL261 and GL261-Quad tumors display characteristic features of human gliomas such as heterogeneous gadolinium leakage and larger T2 weighted volumes. Analysis of brain-infiltrating immune cells demonstrated that GL261-Quad gliomas generate detectable CD8+ T cell responses toward the tumor-specific Kb:OVA257-264 antigen. Enhancing this response via a single intracranial or peripheral vaccination with picornavirus expressing the OVA257-264 antigen increased anti-tumor CD8+ T cells infiltrating the brain, attenuated progression of established tumors, and extended survival of treated mice. Importantly, the efficacy of the picornavirus vaccination is dependent on functional cytotoxic activity of CD8+ T cells, as the beneficial response was completely abrogated in mice lacking perforin expression. Therefore, we have developed a novel system for evaluating mechanisms of anti-tumor immunity in vivo, incorporating the GL261-Quad model, 3D volumetric MRI, and picornavirus vaccination to enhance tumor-specific cytotoxic CD8+ T cell responses and track their effectiveness at eradicating established gliomas in vivo.

Single-fraction radiation therapy in patients with metastatic Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive, polyomavirus-associated cancer with limited therapeutic options for metastatic disease. Cytotoxic chemotherapy is associated with high response rates, but responses are seldom durable and toxicity is considerable. Here, we report our experience with palliative single-fraction radiotherapy (SFRT) in patients with metastatic MCC. We conducted retrospective analyses of safety and efficacy outcomes in patients that received SFRT (8 Gy) to MCC metastases between 2010 and 2013. Twenty-six patients were treated with SFRT to 93 MCC tumors located in diverse sites that included skin, lymph nodes, and visceral organs. Objective responses were observed in 94% of the measurable irradiated tumors (86/92). Complete responses were observed in 45% of tumors (including bulky tumors up to 16 cm). “In field” lesion control was durable with no progression in 77% (69/89) of treated tumors during median follow-up of 277 days among 16 living patients. Clinically significant toxicity was seen in only two patients who had transient side effects. An exploratory analysis suggested a higher rate of in-field progression in patients with an immunosuppressive comorbidity or prior recent chemotherapy versus those without (30% and 9%, respectively; P = 0.03). Use of SFRT in palliating MCC patients was associated with an excellent in field control rate and durable responses at treated sites, and with minimal toxicity. SFRT may represent a convenient and appealing alternative to systemic chemotherapy for palliation, for which most patients with oligometastatic MCC are eligible. SFRT may also synergize with emerging systemic immune stimulants by lowering tumor burden and enhancing presentation of viral/tumor antigens.

Seizure reduction in a low-grade glioma: more than a beneficial side effect of temozolomide

BACKGROUND

Seizures are a common symptom in patients with low-grade glioma (LGG), negatively influencing quality of life, if uncontrolled. Besides antiepileptic drugs, antitumour treatment might contribute to a reduction in seizure frequency. The aim of this study was to determine the effect of temozolomide (TMZ) chemotherapy on seizure frequency, to identify factors associated with post-treatment seizure reduction and to analyse the prognostic value of seizure reduction for survival.

METHODS

We retrospectively reviewed adult patients with supratentorial LGG and epilepsy who received chemotherapy with TMZ as initial treatment or for progressive disease in two hospitals (VUmc Amsterdam; MCH The Hague) between 2002 and 2012.

RESULTS

We identified 104 patients with LGG with epilepsy who had received TMZ. Uncontrolled epilepsy in the 3 months preceding chemotherapy was present in 66 of 104 (63.5%) patients. A ≥ 50% reduction in seizure frequency after 6 months occurred in 29 of 66 (43.9%) patients. Focal symptoms at presentation (OR 6.55; 95% CI 1.45 to 32.77; p = 0.015) appeared to be positively associated with seizure reduction. Seizure reduction was an independent prognostic factor for progression-free survival (HR 0.32; 95% CI 0.15 to 0.66; p = 0.002) and overall survival (HR 0.33; 95% CI 0.14 to 0.79; p = 0.013), along with a histological diagnosis of oligodendroglioma (HR 0.38; 95% CI 0.17 to 0.86; p = 0.021). Objective responses on MRI were similar for patients with and without seizure reduction.

CONCLUSIONS

TMZ may contribute to an important reduction in seizure frequency in patients with LGG. Seizure reduction following TMZ treatment has prognostic significance and may serve as an important clinical outcome measure in patients with LGG.

Seizure outcome after radiotherapy and chemotherapy in low-grade glioma patients: a systematic review

There is growing evidence that antitumor treatment contributes to better seizure control in low-grade glioma patients. We performed a systematic review of the current literature on seizure outcome after radiotherapy and chemotherapy and evaluated the association between seizure outcome and radiological response. Twenty-four studies were available, of which 10 described seizure outcome after radiotherapy and 14 after chemotherapy. All studies demonstrated improvements in seizure outcome after antitumor treatment. Eight studies reporting on imaging response in relation to seizure outcome showed a seizure reduction in a substantial part of patients with stable disease on MRI. Seizure reduction may therefore be the only noticeable effect of antitumor treatment. Our findings demonstrate the clinical relevance of monitoring seizure outcome after radiotherapy and chemotherapy, as well as the potential role of seizure reduction as a complementary marker of tumor response in low-grade glioma patients.

Transgene-derived overexpression of miR-17-92 in CD8+ T-cells confers enhanced cytotoxic activity

MicroRNAs (miRs) play important roles in regulation of a variety of cell functions, including immune responses. We have previously demonstrated that miR-17-92 expression in T-cells enhances Th1 phenotype and provides a long-term protection against glioblastoma when co-expressed as a transgene in T-cells along with a chimeric antigen receptor. To further elucidate the function of miR-17-92 in tumor antigen-specific CD8(+) T-cells, we generated transgenic (Tg) mice in which CD8(+) T-cells overexpress transgene-derived miR-17-92 under the lck promoter as well as T-cell receptor specific for human gp10025-33 (Pmel-1) (miR-17-92/Pmel-Tg). CD8(+) T-cells from miR-17-92/Pmel-Tg mice demonstrated enhanced interferon (IFN)-γ production and cytotoxicity in response to the cognate antigen compared with those from control Pmel-Tg mice without the transgene for miR-17-92. In addition, miR-17-92/Pmel-Tg mouse-derived CD8(+)CD44(+) T-cells demonstrated increased frequencies of cells with memory phenotypes and IFN-γ production. We also found that miR-17-92/Pmel-Tg-derived CD8(+) T-cells expressed decreased levels of transforming growth factor (TGF)-β type II receptor (TGFBR2) on their surface, thereby resisting against suppressive effects of TGF-β1. Our findings suggest that engineering of tumor antigen-specific CD8(+) T-cells to express miR-17-92 may improve the potency of cancer immunotherapy.