Resistance is futile: Targeting the inhibitory FcγRIIB (CD32B) to maximize immunotherapy

Monoclonal antibodies (mAb) are central to the treatment of several types of malignancy. However, these reagents are subject to particular types of resistance. Several resistance mechanisms are regulated by the inhibitory FcγRIIB. We recently developed mAbs to block FcγRIIB and provided in vivo proof-of-concept for their ability to overcome FcγRIIB-mediated resistance.

The Immune System and Responses to Cancer: Coordinated Evolution

This review explores the incessant evolutionary interaction and co-development between immune system evolution and somatic evolution, to put it into context with the short, over 60-year, detailed human study of this extraordinary protective system. Over millions of years, the evolutionary development of the immune system in most species has been continuously shaped by environmental interactions between microbes, and aberrant somatic cells, including malignant cells. Not only has evolution occurred in somatic cells to adapt to environmental pressures for survival purposes, but the immune system and its function has been successively shaped by those same evolving somatic cells and microorganisms through continuous adaptive symbiotic processes of progressive simultaneous immunological and somatic change to provide what we observe today. Indeed, the immune system as an environmental influence has also shaped somatic and microbial evolution. Although the immune system is tuned to primarily controlling microbiological challenges for combatting infection, it can also remove damaged and aberrant cells, including cancer cells to induce long-term cures. Our knowledge of how this occurs is just emerging. Here we consider the connections between immunity, infection and cancer, by searching back in time hundreds of millions of years to when multi-cellular organisms first began. We are gradually appreciating that the immune system has evolved into a truly brilliant and efficient protective mechanism, the importance of which we are just beginning to now comprehend. Understanding these aspects will likely lead to more effective cancer and other therapies.

Novel adjuvant therapies for pancreatic adenocarcinoma

Contemporary adjuvant therapy for pancreatic cancer patients following surgical resection includes chemotherapy and chemoradiotherapy. However, the median survival remains approximately 20 months despite multi-modality treatment using gemcitabine or fluoropyrimidine systemic chemotherapy. Adjuvant randomized trials are currently underway to evaluate cytotoxic combinations found to be active in advanced disease including FOLFIRINOX, gemcitabine/nab-paclitaxel and gemcitabine/capecitabine. Immunotherapy using genetically engineered cell-based vaccines had shown promise in resected pancreatic cancer patients during early phase trials, and algenpantucel-L vaccine is currently being evaluated in adjuvant setting in a randomized trial. This review focuses on novel adjuvant therapies currently in clinical evaluation.

T cells targeting NY-ESO-1 demonstrate efficacy against disseminated neuroblastoma

The cancer-testis antigen NY-ESO-1 is expressed by many solid tumors and has limited expression by mature somatic tissues, making it a highly attractive target for tumor immunotherapy. Targeting NY-ESO-1 using engineered T cells has demonstrated clinical efficacy in the treatment of some adult tumors. Neuroblastoma is a significant cause of cancer mortality in children, and is a tumor type shown to be responsive to immunotherapies. We evaluated a large panel of primarily resected neuroblastoma samples and demonstrated that 23% express NY-ESO-1. After confirming antigen-specific activity of T cells genetically engineered to express an NY-ESO-1 directed high-affinity transgenic T cell receptor in vitro, we performed xenograft mouse studies assessing the efficacy of NY-ESO-1-targeted T cells in both localized and disseminated models of neuroblastoma. Disease responses were monitored by tumor volume measurement and in vivo bioluminescence. After delivery of NY-ESO-1 transgenic TCR T cells, we observed significant delay of tumor progression in mice bearing localized and disseminated neuroblastoma, as well as enhanced animal survival. These data demonstrate that NY-ESO-1 is an antigen target in neuroblastoma and that targeted T cells represent a potential therapeutic option for patients with neuroblastoma.

The Immune System and Responses to Cancer: Coordinated Evolution

This review explores the incessant evolutionary interaction and co-development between immune system evolution and somatic evolution, to put it into context with the short, over 60-year, detailed human study of this extraordinary protective system. Over millions of years, the evolutionary development of the immune system in most species has been continuously shaped by environmental interactions between microbes, and aberrant somatic cells, including malignant cells. Not only has evolution occurred in somatic cells to adapt to environmental pressures for survival purposes, but the immune system and its function has been successively shaped by those same evolving somatic cells and microorganisms through continuous adaptive symbiotic processes of progressive simultaneous immunological and somatic change to provide what we observe today. Indeed, the immune system as an environmental influence has also shaped somatic and microbial evolution. Although the immune system is tuned to primarily controlling microbiological challenges for combatting infection, it can also remove damaged and aberrant cells, including cancer cells to induce long-term cures. Our knowledge of how this occurs is just emerging. Here we consider the connections between immunity, infection and cancer, by searching back in time hundreds of millions of years to when multi-cellular organisms first began. We are gradually appreciating that the immune system has evolved into a truly brilliant and efficient protective mechanism, the importance of which we are just beginning to now comprehend. Understanding these aspects will likely lead to more effective cancer and other therapies.

The intersection of cancer, cancer stem cells, and the immune system: therapeutic opportunities

During brain neoplasia, malignant cells subjugate the immune system to provide an environment that favors tumor growth. These mechanisms capitalize on tumor-promoting functions of various immune cell types and typically result in suppression of tumor immune rejection. Immunotherapy efforts are underway to disrupt these mechanisms and turn the immune system against developing tumors. While many of these therapies are already in early-stage clinical trials, understanding how these therapies impact various tumor cell populations, including self-renewing cancer stem cells, may help to predict their efficacy and clarify their mechanisms of action. Moreover, interrogating the biology of glioma cell, cancer stem cell, and immune cell interactions may provide additional therapeutic targets to leverage against disease progression. In this review, we begin by highlighting a series of investigations into immune cell-mediated tumor promotion that do not parse the tumor into stem and non-stem components. We then take a closer look at the immune-suppressive mechanisms derived specifically from cancer stem cell interactions with the immune system and end with an update on immunotherapy and cancer stem cell-directed clinical trials in glioblastoma.

Pharmacologic options for the treatment and management of food allergy

Food allergy affects approximately 5% of adults and 8% of children in developed countries, and there is currently no cure. Current pharmacologic management is limited to using intramuscular epinephrine or oral antihistamines in response to food allergen exposure. Recent trials have examined the efficacy and safety of subcutaneous, oral, sublingual, and epicutaneous immunotherapy, with varying levels of efficacy and safety demonstrated. Bacterial adjuvants, use of anti-IgE monoclonal antibodies, and Chinese herbal formulations represent exciting potential for development of future pharmacotherapeutic agents. Ultimately, immunotherapy may be a viable option for patients with food allergy, although efficacy and safety are likely to be less than ideal.

Antibodies targeting human IL1RAP (IL1R3) show therapeutic effects in xenograft models of acute myeloid leukemia

Acute myeloid leukemia (AML) is associated with a poor survival rate, and there is an urgent need for novel and more efficient therapies, ideally targeting AML stem cells that are essential for maintaining the disease. The interleukin 1 receptor accessory protein (IL1RAP; IL1R3) is expressed on candidate leukemic stem cells in the majority of AML patients, but not on normal hematopoietic stem cells. We show here that monoclonal antibodies targeting IL1RAP have strong antileukemic effects in xenograft models of human AML. We demonstrate that effector-cell-mediated killing is essential for the observed therapeutic effects and that natural killer cells constitute a critical human effector cell type. Because IL-1 signaling is important for the growth of AML cells, we generated an IL1RAP-targeting antibody capable of blocking IL-1 signaling and show that this antibody suppresses the proliferation of primary human AML cells. Hence, IL1RAP can be efficiently targeted with an anti-IL1RAP antibody capable of both achieving antibody-dependent cellular cytotoxicity and blocking of IL-1 signaling as modes of action. Collectively, these results provide important evidence in support of IL1RAP as a target for antibody-based treatment of AML.

Dendritic cell-based immunotherapy targeting Wilms' tumor 1 in patients with recurrent malignant glioma

OBJECT

Dendritic cell (DC)-based vaccination is considered a potentially effective therapy against advanced cancer. The authors conducted a Phase I study to investigate the safety and immunomonitoring of Wilms' tumor 1 (WT1)-pulsed DC vaccination therapy for patients with relapsed malignant glioma.

METHODS

WT1-pulsed and/or autologous tumor lysate-pulsed DC vaccination therapy was performed in patients with relapsed malignant gliomas. Approximately 1 × 10(7) to 2 × 10(7) pulsed DCs loaded with WT1 peptide antigen and/or tumor lysate were intradermally injected into the axillary areas with OK-432, a streptococcal preparation, at 2-week intervals for at least 5-7 sessions (1 course) during an individual chemotherapy regimen.

RESULTS

Ten patients (3 men, 7 women; age range 24-64 years [median 39 years]) with the following tumors were enrolled: glioblastoma (6), anaplastic astrocytoma (2), anaplastic oligoastrocytoma (1), and anaplastic oligodendroglioma (1). Modified WT1 peptide-pulsed DC vaccine was administered to 7 patients, tumor lysate-pulsed DC vaccine to 2 patients, and both tumor lysate-pulsed and WT1-pulsed DC vaccine to 1 patient. The clinical response was stable disease in 5 patients with WT1-pulsed DC vaccination. In 2 of 5 patients with stable disease, neurological findings improved, and MR images showed tumor shrinkage. No serious adverse events occurred except Grade 1-2 erythema at the injection sites. WT1 tetramer analysis detected WT1-reactive cytotoxic T cells after vaccination in patients treated with WT1-pulsed therapy. Positivity for skin reaction at the injection sites was 80% (8 of 10 patients) after the first session, and positivity remained for these 8 patients after the final session.

CONCLUSIONS

This study of WT1-pulsed DC vaccination therapy demonstrated safety, immunogenicity, and feasibility in the management of relapsed malignant gliomas.

Dihydrofolate Reductase and Thymidylate Synthase Transgenes Resistant to Methotrexate Interact to Permit Novel Transgene Regulation

Methotrexate (MTX) is an anti-folate that inhibits de novo purine and thymidine nucleotide synthesis. MTX induces death in rapidly replicating cells and is used in the treatment of multiple cancers. MTX inhibits thymidine synthesis by targeting dihydrofolate reductase (DHFR) and thymidylate synthase (TYMS). The use of MTX to treat cancer also causes bone marrow suppression and inhibits the immune system. This has led to the development of an MTX-resistant DHFR, DHFR L22F, F31S (DHFR(FS)), to rescue healthy cells. 5-Fluorouracil-resistant TYMS T51S, G52S (TYMS(SS)) is resistant to MTX and improves MTX resistance of DHFR(FS) in primary T cells. Here we find that a known mechanism of MTX-induced increase in DHFR expression persists with DHFR(FS) and cis-expressed transgenes. We also find that TYMS(SS) expression of cis-expressed transgenes is similarly decreased in an MTX-inducible manner. MTX-inducible changes in DHFR(FS) and TYMS(SS) expression changes are lost when both genes are expressed together. In fact, expression of the DHFR(FS) and TYMS(SS) cis-expressed transgenes becomes correlated. These findings provide the basis for an unrecognized post-transcriptional mechanism that functionally links expression of DHFR and TYMS. These findings were made in genetically modified primary human T cells and have a clear potential for use in clinical applications where gene expression needs to be regulated by drug or maintained at a specific expression level. We demonstrate a potential application of this system in the controlled expression of systemically toxic cytokine IL-12.

Efficacy of cytokine-induced killer cells in the treatment of elderly patients with metastatic pancreatic adenocarcinoma

Currently, metastatic pancreatic cancer is associated with disappointing survival outcomes. This is largely due to a rapid progression of the disease and a precipitous deterioration in the health of affected individuals, especially elderly patients who are often unable to tolerate chemotherapy. The aim of this study was to evaluate the efficacy and safety of adoptive immunotherapy using cytokine-induced killer cells (CIK) as a first-line treatment for metastatic pancreatic cancer. Between December 2010 and June 2012 eight patients were enrolled in this study. All participants were elderly, suffering from metastatic pancreatic cancer, and unable to tolerate chemotherapy. All patients in this study received R-CIK therapy only as a first-line treatment. In the eight patients, 1 had complete response (CR), 5 had stable disease (SD) and 2 had progression disease (PD). Therefore, the overall response rate (ORR) was 12.5% (1/8) and the disease control rate (DCR) was 75.0% (6/8 patients). The 1-year survival rate was 37.5%, and the median overall survival time (mOS) was 13.04 months (95% CI: 5.9-20.2). The results indicated that no significant positive or negative predictive factors were identified by univariate analysis. The main adverse effect of R-CIK was fever and the side effect rate was 25.0% (2/8). Adoptive immunotherapy using R-CIK cells showed comparable OS to survival data seen in previous trials assessing conventional chemotherapies in elderly patients and the adverse effect is less pronounced.

Comparative Immunogenicity of a Cytotoxic T Cell Epitope Delivered by Penetratin and TAT Cell Penetrating Peptides

Cell penetrating peptides (CPP), including the TAT peptide from the human immunodeficiency virus transactivator of transcription (HIV-TAT) protein and penetratin from Drosophila Antennapedia homeodomain protein, translocate various cargos including peptides and proteins across cellular barriers. This mode of delivery has been harnessed by our group and others to deliver antigenic proteins or peptides into the cytoplasm of antigen processing cells (APC) such as monocyte-derived dendritic cells (MoDC). Antigens or T cell epitopes delivered by CPP into APC in vivo generate antigen-specific cytotoxic T cell and helper T cell responses in mice. Furthermore, mice immunised with these peptides or proteins are protected from a tumour challenge. The functional properties of CPP are dependent on the various cargos being delivered and the target cell type. Despite several studies demonstrating superior immunogenicity of TAT and Antp-based immunogens, none has compared the immunogenicity of antigens delivered by TAT and Antp CPP. In the current study we demonstrate that a cytotoxic T cell epitope from the mucin 1 (MUC1) tumour associated antigen, when delivered by TAT or Antp, generates identical immune responses in mice resulting in specific MUC1 T cell responses as measured by in vivo CTL assays, IFNγ ELISpot assays and prophylactic tumour protection.

Extended evaluation of a phase 1/2 trial on dosing, safety, immunogenicity, and overall survival after immunizations with an advanced-generation Ad5 [E1-, E2b-]-CEA(6D) vaccine in late-stage colorectal cancer

A phase 1/2 clinical trial evaluating dosing, safety, immunogenicity, and overall survival on metastatic colorectal cancer (mCRC) patients after immunotherapy with an advanced-generation Ad5 [E1-, E2b-]-CEA(6D) vaccine was performed. We report our extended observations on long-term overall survival and further immune analyses on a subset of treated patients including assessment of cytolytic T cell responses, T regulatory (Treg) to T effector (Teff) cell ratios, flow cytometry on peripheral blood mononuclear cells (PBMCs), and determination of HLA-A2 status. An overall survival of 20 % (median survival 11 months) was observed during long-term follow-up, and no long-term adverse effects were reported. Cytolytic T cell responses increased after immunizations, and cell-mediated immune (CMI) responses were induced whether or not patients were HLA-A2 positive or Ad5 immune. PBMC samples from a small subset of patients were available for follow-up immune analyses. It was observed that the levels of carcinoembryonic antigen (CEA)-specific CMI activity decreased from their peak values during follow-up in five patients analyzed. Preliminary results revealed that activated CD4+ and CD8+ T cells were detected in a post-immunization sample exhibiting high CMI activity. Treg to Teff cell ratios were assessed, and samples from three of five patients exhibited a decrease in Treg to Teff cell ratio during the treatment protocol. Based upon the favorable safety and immunogenicity data obtained, we plan to perform an extensive immunologic and survival analysis on mCRC patients to be enrolled in a randomized/controlled clinical trial that investigates Ad5 [E1-, E2b-]-CEA(6D) as a single agent with booster immunizations.

Dendritic cells transfected with heat-shock protein 70 messenger RNA for patients with hepatitis C virus-related hepatocellular carcinoma: a phase 1 dose escalation clinical trial

BACKGROUND

We previously reported overexpression of heat-shock protein (HSP) 70 in hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC) using proteomic profiling and immunohistochemical staining (IHS). This suggested that HSP70 could be a molecular target for treatment of HCC.

METHODS

Twelve patients with HCV-related HCC were enrolled in a phase 1 clinical trial. Dendritic cells (DCs) transfected with HSP70 mRNA (HSP70-DCs) induced by electroporation were injected intradermally. Patients were treated three times every 3 weeks. The number of HSP70-DCs injected was 1 × 10(7) as the lowest dose, then 2 × 10(7) as the medium dose, and then 3 × 10(7) as the highest dose. Immunological analyses were performed.

FINDINGS

No adverse effects of grade III/IV, except one grade III liver abscess at the 3 × 10(7) dose, were observed. Thus, we added three more patients to confirm whether 3 × 10(7) is an appropriate dose. Eventually, we chose 3 × 10(7) as the recommended dose of DCs. Complete response (CR) without any recurrence occurred in two patients, stable disease in five, and progression of disease in five. The two patients with CR have had no recurrence for 44 and 33 months, respectively. IHS in one patient who underwent partial hepatectomy showed infiltration of CD8+ T cells and granzyme B in tumors, indicating that the dominant immune effector cells were cytotoxic T lymphocytes with tumor-killing activity.

INTERPRETATION

This study demonstrated that HSP70-DCs therapy is both safe and feasible in patients with HCV-related HCC. Further clinical trials should be considered.

Immune checkpoint inhibitors in melanoma

The potential to harness the power of the immune system and effectively treat patients with metastatic melanoma is finally being realized with the advent of immune checkpoint inhibitors. These new therapies herald a new era in the treatment of melanoma with the potential to produce very durable responses and possible cure for a subset of patients, though bring with them challenges including novel toxicities and nonconventional response patterns. This article reviews the currently available immune checkpoint inhibitors, potential biomarkers to predict response and promising investigational approaches including combination therapies.

Clinical Management of Multiple Melanoma Brain Metastases: A Systematic Review

IMPORTANCE

The treatment of multiple brain metastases (MBM) from melanoma is controversial and includes surgical resection, stereotactic radiosurgery (SRS), and whole-brain radiation therapy (WBRT). Several new classes of agents have revolutionized the treatment of metastatic melanoma, allowing some subsets of patients to have long-term survival. Given this, management of MBM from melanoma is continually evolving.

OBJECTIVE

To review the current evidence regarding the treatment of MBM from melanoma.

EVIDENCE REVIEW

The PubMed database was searched using combinations of search terms and synonyms for melanoma, brain metastases, radiation, chemotherapy, immunotherapy, and targeted therapy published between January 1, 1995, and January 1, 2015. Articles were selected for inclusion on the basis of targeted keyword searches, manual review of bibliographies, and whether the article was a clinical trial, large observational study, or retrospective study focusing on melanoma brain metastases. Of 2243 articles initially identified, 110 were selected for full review. Of these, the most pertinent 73 articles were included.

FINDINGS

Patients with newly diagnosed MBM can be treated with various modalities, either alone or in combination. Level 1 evidence supports the use of SRS alone, WBRT, and SRS with WBRT. Although the addition of WBRT to SRS improves the overall brain relapse rate, WBRT has no significant impact on overall survival and has detrimental neurocognitive outcomes. Cytotoxic chemotherapy has largely been ineffective; targeted therapies and immunotherapies have been reported to have high response rates and deserve further attention in larger clinical trials. Further studies are needed to fully evaluate the efficacy of these novel regimens in combination with radiation therapy.

CONCLUSIONS AND RELEVANCE

At this time, the standard management for patients with MBM from melanoma includes SRS, WBRT, or a combination of both. Emerging data exist to support the notion that SRS in combination with targeted therapies or immune therapy may obviate the need for WBRT; prospective studies are required to fully evaluate the efficacy of these novel regimens in combination with radiation therapy.

Neuroblastoma Arginase Activity Creates an Immunosuppressive Microenvironment That Impairs Autologous and Engineered Immunity

Neuroblastoma is the most common extracranial solid tumor of childhood, and survival remains poor for patients with advanced disease. Novel immune therapies are currently in development, but clinical outcomes have not matched preclinical results. Here, we describe key mechanisms in which neuroblastoma inhibits the immune response. We show that murine and human neuroblastoma tumor cells suppress T-cell proliferation through increased arginase activity. Arginase II is the predominant isoform expressed and creates an arginine-deplete local and systemic microenvironment. Neuroblastoma arginase activity results in inhibition of myeloid cell activation and suppression of bone marrow CD34(+) progenitor proliferation. Finally, we demonstrate that the arginase activity of neuroblastoma impairs NY-ESO-1-specific T-cell receptor and GD2-specific chimeric antigen receptor-engineered T-cell proliferation and cytotoxicity. High arginase II expression correlates with poor survival for patients with neuroblastoma. The results support the hypothesis that neuroblastoma creates an arginase-dependent immunosuppressive microenvironment in both the tumor and blood that leads to impaired immunosurveillance and suboptimal efficacy of immunotherapeutic approaches.

Optimal selection of natural killer cells to kill myeloma: the role of HLA-E and NKG2A

Immunotherapy with allogeneic natural killer (NK) cells offers therapeutic perspectives for multiple myeloma patients. Here, we aimed to refine NK cell therapy by evaluation of the relevance of HLA-class I and HLA-E for NK anti-myeloma reactivity. We show that HLA-class I was strongly expressed on the surface of patient-derived myeloma cells and on myeloma cell lines. HLA-E was highly expressed by primary myeloma cells but only marginally by cell lines. HLA-E(low) expression on U266 cells observed in vitro was strongly upregulated after in vivo (bone marrow) growth in RAG-2(-/-) γc(-/-) mice, suggesting that in vitro HLA-E levels poorly predict the in vivo situation. Concurrent analysis of inhibitory receptors (KIR2DL1, KIR2DL2/3, KIR3DL1 and NKG2A) and NK cell degranulation upon co-culture with myeloma cells revealed that KIR-ligand-mismatched NK cells degranulate more than matched subsets and that HLA-E abrogates degranulation of NKG2A+ subsets. Inhibition by HLA-class I and HLA-E was also observed with IL-2-activated NK cells and at low oxygen levels (0.6 %) mimicking hypoxic bone marrow niches where myeloma cells preferentially reside. Our study demonstrates that NKG2A-negative, KIR-ligand-mismatched NK cells are the most potent subset for clinical application. We envision that infusion of high numbers of this subclass will enhance clinical efficacy.

Clinical significance of programmed death ligand-1 (PD-L1) in colorectal serrated adenocarcinoma

Preliminary research results with antibody of the negative costimulatory molecule programmed cell death ligand-1 (PD-L1) suggested its expression on tumor cells associated with various tumor grade and postoperative prognosis. However, to date, there is no information of PD-L1 expression in colorectal serrated adenocarcinoma (SAC) and its clinical relevance. Therefore, the purpose of this study is to investigate the clinical significance of PD-L1 expression in a large cohort of patients with SAC. Here, we first retrospectively identified all SAC collected at our institution between August 2008 and May 2013. The expression levels of PD-L1 were examined by immunohistochemistry in 120 patients with SAC. We further evaluated the correlation between expression data and clinical parameters, including patient age, sex, tumor size, location, grade, primary tumor classification (pT), lymph node metastasis (pN), distant metastases (pM), and vascular invasion. Strong PD-L1 expression was detected in 25% of SAC. Higher expression of PD-L1 was significantly associated with pN (P=0.003) and pM (P=0.014). Survival analysis showed that patients with higher expression of PD-L1 had a poorer prognosis (P=0.045). However, multivariate regression analysis did not support PD-L1 as an independent prognostic factor (P=0.430). Our data suggest that PD-L1 may represent a new biomarker of metastasis and prognosis for patients with SAC, but as a target in the treatment of SAC is less certain.

Chimeric antigen receptors and bispecific antibodies to retarget T cells in pediatric oncology

Cancer immunotherapy using antigen-specific T cells has broad therapeutic potential. Chimeric antigen receptors and bispecific antibodies can redirect T cells to kill tumors without human leukocyte antigens (HLA) restriction. Key determinants of clinical potential include the choice of target antigen, antibody specificity, antibody affinity, tumor accessibility, T cell persistence, and tumor immune evasion. For pediatric cancers, additional constraints include their propensity for bulky metastatic disease and the concern for late toxicities from treatment. Nonetheless, the recent preclinical and clinical developments of these T cell based therapies are highly encouraging.

Idiotypic DNA vaccination for the treatment of multiple myeloma: safety and immunogenicity in a phase I clinical study

We report on the safety and immunogenicity of idiotypic DNA vaccination in a phase I, non-randomised, open-label study in patients with multiple myeloma. The study used DNA fusion gene vaccines encoding patient-specific single chain variable fragment, or idiotype (Id), linked to fragment C (FrC) of tetanus toxin. Patients in complete or partial response following high-dose chemotherapy and autologous stem cell transplant were vaccinated intramuscularly with 1 mg DNA on six occasions, beginning at least 6 months post-transplant; follow-up was to week 52. Fourteen patients were enrolled on study and completed vaccinations. Idiotypic DNA vaccines were well tolerated with vaccine-related adverse events limited to low-grade constitutional symptoms. FrC- and Id-specific T-cell responses were detected by ex vivo ELISPOT in 9/14 and 3/14 patients, respectively. A boost of pre-existing anti-FrC antibody (Ab) was detected by ELISA in 8/14 patients, whilst anti-Id Ab was generated in 1/13 patients. Overall, four patients (29 %) made an immune response to FrC and Id, with six patients (43 %) responding to FrC alone. Over the 52-week study period, serum paraprotein was undetectable, decreased or remained stable for ten patients (71 %), whilst ongoing CR/PR was maintained for 11 patients (79 %). The median time to progression was 38.0 months for 13/14 patients. Overall survival was 64 % after a median follow-up of 85.6 months.

Management of melanoma brain metastases

Relapses in the brain remain a major obstacle to cure in many patients with advanced melanoma. At present, the management of melanoma brain metastases continues to rely heavily on surgical and radiotherapeutic interventions, which have become safer and more effective with modern imaging, surgery and radiation technologies. Additionally, novel targeted and immunotherapeutic agents, shown to generate meaningful intracranial response and survival benefit in patients with melanoma brain metastases when compared with historical controls, expand systemic treatment options for this subset of patients. These systemic therapies become particularly important when intracranial disease burden precludes neuro- or radio-surgery. Considerable multidisciplinary research effort is ongoing to improve outcomes for melanoma patients with brain metastases, a key challenge in the management of advanced melanoma.

Intranodal vaccination with mRNA-optimized dendritic cells in metastatic melanoma patients

Autologous dendritic cell (DC) therapy is an experimental cellular immunotherapy that is safe and immunogenic in patients with advanced melanoma. In an attempt to further improve the therapeutic responses, we treated 15 patients with melanoma, with autologous monocyte-derived immature DC electroporated with mRNA encoding CD40 ligand (CD40L), CD70 and a constitutively active TLR4 (caTLR4) together with mRNA encoding a tumor-associated antigen (TAA; respectively gp100 or tyrosinase). In addition, DC were pulsed with keyhole limpet hemocyanin (KLH) that served as a control antigen. Production of this DC vaccine with high cellular viability, high expression of co-stimulatory molecules and MHC class I and II and production of IL-12p70, was feasible in all patients. A vaccination cycle consisting of three vaccinations with up to 15×106 DC per vaccination at a biweekly interval, was repeated after 6 and 12 months in the absence of disease progression. mRNA-optimized DC were injected intranodally, because of low CCR7 expression on the DC, and induced de novo immune responses against control antigen. T cell responses against tyrosinase were detected in the skin-test infiltrating lymphocytes (SKIL) of two patients. One mixed tumor response and two durable tumor stabilizations were observed among 8 patients with evaluable disease at baseline. In conclusion, autologous mRNA-optimized DC can be safely administered intranodally to patients with metastatic melanoma but showed limited immunological responses against tyrosinase and gp100.