Vaccination: role in metastatic melanoma

Immune system functional pathway analysis using single cell network profiling (SCNP): a novel tool in cancer immunotherapy

The development of cancer immunotherapies has been ongoing for many years and has shown limited success. Novel biomarkers are needed to identify patients most likely to respond to anticancer immune-therapeutic approaches. Moreover, a systems-level approach is required for comprehensive understanding of the interconnected components, pathways, and cell types associated with an immune response. In this chapter, we describe single cell network profiling (SCNP), a novel method for assessing and measuring immune function/dysfunction at a systems level. SCNP is a multiparametric flow-cytometry-based analysis that can simultaneously measure, at the single cell level, both extracellular surface markers and changes in intracellular signaling proteins in response to extracellular modulators. Measuring changes in signaling proteins following the application of an external modulation informs on the functional capacity of the signaling network which cannot be assessed by the measurement of basal signaling alone. In addition, the simultaneous analysis of multiple pathways in multiple cell subsets can provide insight into the connectivity of both cell signaling networks and immune cell subtypes. The experimental steps associated with an SCNP assay are (1) pre-analytical sample preparation; (2) modulation for functional analysis; (3) staining with antibody cocktail; (4) data acquisition on flow cytometer; and (5) data analysis and metrics. Important considerations for each step of the assay will be discussed, and data demonstrating the utility of SCNP for immune monitoring applications will be summarized.

Individual patient-specific immunity against high-grade glioma after vaccination with autologous tumor derived peptides bound to the 96 KD chaperone protein

PURPOSE

Cancer immunotherapy offers hope of a highly specific nontoxic adjuvant treatment. Heat shock protein peptide complexes (HSPPCs) found in cancer cells carry tumor-specific antigenic proteins and can facilitate adaptive and innate immune responses. Here we show that peptides bound to a 96 kD chaperone protein (HSP-96) from brain tissue containing glioblastoma multiforme (GBM) can be used to safely immunize patients with recurrent GBM.

EXPERIMENTAL DESIGN

Multimodality immunomonitoring was completed on 12 patients with recurrent GBM before and after immunization with an autologous HSPPC vaccine derived from surgically resected tumor. Clinical endpoints included safety assessments and overall survival.

RESULTS

No adverse events attributable to the vaccine were found. Testing of peripheral blood leukocytes before and after vaccination revealed a significant peripheral immune response specific for the peptides bound to HSP-96, in 11 of the 12 patients treated. Brain biopsies of immune responders after vaccination revealed focal CD4, CD8, and CD56 IFNγ positive cell infiltrates, consistent with tumor site specific immune responses. Immune responders had a median survival of 47 weeks after surgery and vaccination, compared with 16 weeks for the single nonresponder.

CONCLUSIONS

These data provide the first evidence in humans of individual patient-specific immune responses against autologous tumor derived peptides bound to HSP-96.

Inhibition of melanoma growth by subcutaneous administration of hTERTC27 viral cocktail in C57BL/6 mice

Background

hTERTC27 is a 27 kDa C-terminal polypeptide of human telomerase reverse transcriptase that has previously been shown to reduce tumorigenicity of HeLa cells and suppress growth of xenografted glioblastoma in nude mice. Although ectopic expression of hTERTC27 upregulated genes that are involved in apoptosis, cell cycle, and immune response, the mechanism for hTERTC27-induced tumor suppression has not been completely elucidated. Since hTERT was identified as a universal tumor-associated antigen, we hypothesize that hTERTC27 inhibits tumor growth in vivo through activation of anti-tumor immune response.

Methodology/Principal Finding

Immunocopetent C57BL/6 mice were used for mouse B16 melanoma model. Mice bearing B16 melanoma were administered rAAV-/rAdv viral cocktail expressing hTERTC27, and tumor growth was monitored after viral cocktail treatment. Blood and splenocytes were used to determine the level of cytokines and the activity of immune cells, respectively. B16 tumor growth was significantly inhibited by subcutaneous administration of a single dose of 1.5×10¹¹ vg rAAV-hTERTC27 and 2.5×10⁹ pfu rAdv-hTERTC27 viral cocktail (rAAV-/rAdv-hTERTC27). The population and cytotoxicity of NK cells in the mice were significantly augmented by rAAV-/rAdv-hTERTC27 treatment, and selective depletion of the NK cell population in mice by intraperitoneal injection of anti-GM1 antibody abrogated the growth suppression of melanoma induced by rAAV-/rAdv-hTERTC27 administration.

Conclusion

Activation of NK cells by administration of rAAV-/rAdv-hTERTC27 is critical for growth suppression of melanoma in mouse model.

Novel immunotherapies as potential therapeutic partners for traditional or targeted agents: cytotoxic T-lymphocyte antigen-4 blockade in advanced melanoma

The successful management of advanced melanoma remains an unmet need because of a resolutely poor prognosis and therapeutic options with limited effectiveness. Dacarbazine and fotemustine are the only approved chemotherapeutic agents for advanced melanoma, yet neither alone or in combination regimens has been shown to extend survival in randomized clinical trials. The only agent to be approved for advanced melanoma in the US in more than 30 years is high-dose bolus interleukin-2, but its use is associated with high toxicity and cost, and it has also failed to show a survival benefit. Our expanding knowledge of the complex factors and pathways regulating immune function has led to the advent of novel immunotherapeutic agents. Among these are ipilimumab and tremelimumab - fully human, monoclonal antibodies directed against cytotoxic T-lymphocyte antigen-4 (CTLA-4). The pivotal role of CTLA-4 in regulating T-cell function is established, and a series of preclinical studies provided proof-of-concept evidence of the antitumor activity of anti-CLTA-4 antibodies in combination with vaccines or chemotherapy. Subsequently, anti-CTLA-4 antibodies have shown encouraging results in clinical trials in advanced melanoma. Recent progress in the understanding of melanoma genetics and tumorigenesis has led to potential new therapeutic targets. Molecular targeted agents that inhibit the proliferation and survival of metastatic melanoma cells offer potential partners for anti-CTLA-4 antibodies in combined modality regimens. Novel combinations are reviewed in the context of creating an immunosupportive environment in the host.

Clinical and immunological responses in metastatic melanoma patients vaccinated with a high-dose poly-epitope vaccine

BACKGROUND

Safety and cellular immunogenicity of rising doses and varying regimens of a poly-epitope vaccine were evaluated in advanced metastatic melanoma. The vaccine comprised plasmid DNA and recombinant modified vaccinia virus Ankara (MVA) both expressing a string (Mel3) of seven HLA.A2/A1 epitopes from five melanoma antigens.

METHODS

Forty-one HLA-A2 positive patients with stage III/IV melanoma were enrolled. Patient groups received one or two doses of DNA.Mel3 followed by escalating doses of MVA.Mel3. Immunisations then continued eight weekly in the absence of disease progression. Epitope-specific CD8+ T cell responses were evaluated using ex-vivo tetramer and IFN-gamma ELISPOT assays. Safety and clinical responses were monitored.

RESULTS

Prime-boost DNA/MVA induced Melan-A-specific CD8+ T cell responses in 22/31 (71%) patients detected by tetramer assay. ELISPOT detected a response to at least one epitope in 10/31 (32%) patients. T cell responder rates were <50% with low-dose DNA/MVA, or MVA alone, rising to 91% with high-dose DNA/MVA. Among eight patients showing evidence of clinical benefit-one PR (24 months+), five SD (5 months+) and two mixed responses-seven had associated immune responses. Melan-A-tetramer+ immunity was associated with a median 8-week increase in time-to-progression (P = 0.037) and 71 week increase in survival (P = 0.0002) compared to non-immunity. High-dose vaccine was well tolerated. The only significant toxicities were flu-like symptoms and injection-site reactions.

CONCLUSIONS

DNA.Mel3 and MVA.Mel3 in a prime-boost protocol generated high rates of immune response to melanoma antigen epitopes. The treatment was well tolerated and the correlation of immune responses with patient outcomes encourages further investigation.

Increased interstitial pressure improves nucleic acid delivery to skin enabling a comparative analysis of constitutive promoters

Nucleic acid-based therapies hold great promise for treatment of skin disorders if delivery challenges can be overcome. To investigate one mechanism of nucleic acid delivery to keratinocytes, a fixed mass of expression plasmid was intradermally injected into mouse footpads in different volumes, and reporter expression was monitored by intravital imaging or skin sectioning. Reporter gene expression increased with higher delivery volumes, suggesting that pressure drives nucleic acid uptake into cells after intradermal injections similar to previously published studies for muscle and liver. For spatiotemporal analysis of reporter gene expression, a dual-axis confocal (DAC) fluorescence microscope was used for intravital imaging following intradermal injections. Individual keratinocytes expressing hMGFP were readily visualized in vivo and initially appeared to preferentially express in the stratum granulosum and subsequently migrate to the stratum corneum over time. Fluorescence microscopy of frozen skin sections confirmed the patterns observed by intravital imaging. Intravital imaging with the DAC microscope is a noninvasive method for probing spatiotemporal control of gene expression and should facilitate development and testing of new nucleic acid delivery technologies.

A biofilm growth protocol and the design of a magnetic field exposure setup to be used in the study of magnetic fields as a means of controlling bacterial biofilms

The use of prosthetic implants is increasing both in the United States and around the world and there is a concomitant rise in cases of biofilm-based, persistent infections that are quite serious and virtually impervious to antibiotic treatment. The development of alternate therapies that do not involve long term use of high levels of antibiotics or surgical intervention is needed. Based on the success of using electric or magnetic fields to alter certain physiological processes, it is hypothesized that relatively low level magnetic fields, in conjunction with the appropriate antibiotic, may be able to help control and eventually clear bacterial biofilms on a prosthetic. In order to test this hypothesis, it is necessary to first develop a means of growing laboratory grade biofilms on specific materials in a way that is repeatable between experiments and that can be reproduced by other laboratories. Secondly, a means of applying controlled magnetic fields to the surfaces supporting the biofilms at a defined temperature must be developed. This article addresses both of these points.

Multipeptide vaccination in cancer patients

Since the identification of tumor associated antigens (TAA) in different tumor histotypes, many vaccination strategies have been investigated, including peptide-based vaccines. Results from the first decade of clinical experimentation, though demonstrating the feasibility and the good toxicity profile of this approach, provided evidence of clinical activity only in a minority of patients, despite inducing immunization in up to 50% of them. In this review, we discuss the different approaches recently developed in order to induce stronger peptide-induced immune-mediated tumor growth control, possibly translating into improved clinical response rates, with specific focus on multipeptide-based anti-cancer vaccines. This strategy offers many advantages, such as the possibility of bypassing tumor heterogeneity and selection of antigen (Ag)-negative clones escaping peptide-specific immune responses, or combining HLA class I- and class II-restricted epitopes, thus eliciting both CD4- and CD8-mediated immune recognition. Notably, advances in Ag discovery technologies permit further optimization of peptide selection, in terms of identification of tumor-specific and unique TAA as well as Ags derived from different tumor microenvironment cell components. With the ultimate goal of combining peptide selection with patient-specific immunogenic profile, peptide based anti-cancer vaccines remain a promising treatment for cancer patients, as attested by of pre-clinical and clinical studies.

Current clinical overview of cutaneous melanoma

This article reviews current evidence on epidemiology, diagnosis and management of cutaneous melanoma. Incidence of cutaneous melanoma is rising in all Caucasian populations across the world; thus, melanoma represents a significant public health burden. Although, incidence of melanoma is in continuous increase, a decrease of mortality and improved survival has been observed in most western European populations. Clinical characteristics of four major types of melanoma (superficial spreading, nodular, lentigo maligna melanoma and acral lentiginous melanoma) have been described. Surgical removal of melanoma remains the standard care in all primary melanomas. Current evidence suggests use of 1 to 2 cm excision margins. Wider margins may be necessary in patients with thicker melanomas with higher risk for local recurrence. In the treatment of regional lymph nodes elective lymphadenectomy has been surpassed by the sentinel lymph node biopsy (SLNB). However, although prognostic value of SLNB has been confirmed, its therapeutical benefit still needs to be evaluated. Currently there is no standard adjuvant therapy for melanoma although interferon-alpha has been the most widely used treatment in the adjuvant setting. The role of metastasectomy (removal of distant metastases) is still controversial. Chemotherapeutic agents have a limited activity in patients with metastatic melanoma with response rates up to 25%. Although different vaccines have been tested in melanoma patients their role still remain to be established in phase III trials. Progresses in molecular biology and genetics of melanoma may lead to the development of novel melanoma therapies.

Monocyte-derived IL-10 expression predicts prognosis of stage IV melanoma patients

There are no standard methods to predict response to treatment or outcome of stage IV melanoma. Our previous assessment of peripheral blood mononuclear cells (PBMC) from immunized patients demonstrated that interleukin (IL)-10 expression might be associated with prognosis. However, PBMC are a mixture of CD4+ cells, CD8+ cells, and monocytes. This study identified the subset of PBMC responsible for IL-10 expression and evaluated the prognostic value of IL-10 expression in immunized stage IV patients. Eighty-seven patients with stage IV melanoma were randomly selected from our database. All patients had received an allogeneic melanoma whole-cell vaccine (Canvaxin) after complete resection of clinical disease. Blood samples had been collected serially during Canvaxin administration and cryopreserved. Intracellular IL-10 expression was assessed by double staining fluorescence-activated cell sorter. CD14+ monocytes are the predominant PBMC producing IL-10. Sixteen weeks after treatment (week 16), IL-10 levels were significantly (P=0.02) higher in poor-survival patients than those with favorable outcomes. Patients were separated into 2 groups on the basis of the CD14+ monocyte IL-10 response: either increasing or decreasing IL-10 expression from preimmunization (week 0) to week 16 blood draws. Patients with increasing IL-10 levels had significantly shorter survival than those whose IL-10 levels decreased at week 16 (P<0.0001). Multivariate analysis demonstrated that trends in IL-10 levels inversely correlated with survival (P<0.0001). We conclude that CD14+ monocytes are the dominant cellular source of IL-10 among PBMC and that changes in IL-10 expression may serve as an immunologic-based surrogate for predicting outcome for stage IV patients after surgical resection.

Allogeneic tumor-cell-based vaccines secreting endoplasmic reticulum chaperone gp96

Heat-shock proteins are chaperones for proteins including tumor antigens. Heat-shock protein gp96, also known as glucose-regulated protein grp94, is the primary chaperone of the endoplasmic reticulum and a natural adjuvant for priming the innate and adaptive immune system. By transfecting tumor cells with a genetically modified secretory form of gp96, the tumor cells are transformed into vaccine cells. Gp96 vaccines in murine studies trigger robust innate and antigen-specific cellular immune responses and cause tumor rejection followed by long-lasting tumor immunity. The authors briefly review here the generation of cytotoxic T lymphocyte responses by gp96 and the most up to date clinical data in the use of gp96-based cancer vaccines.

HLA-G expression in malignant melanoma

Both, the expression of HLA-G (a non-classical HLA class I molecule) and the loss of classical HLA class I molecules enable tumor cells to evade from immunosurveillance of the host. Whereas HLA-G down-modulates the immune functions of all cells participating in the immune defence mechanisms, defects on HLA class I expression result in the resistance of tumor cells to cytotoxic T lymphocytes attacks. This contribution reviews the HLA-G expression pattern in malignant melanoma lesions, its correlation to the loss of classical HLA class I antigens, and new aspects of HLA-G regulation.

New approaches in metastatic melanoma: biological and molecular targeted therapies

Classical metastatic melanoma therapy is disappointing but important progress has been made in the understanding of melanoma biology. Genetic lesions and several intracellular signaling pathways that could serve as targets for novel therapy have been identified and a number of new agents are under evaluation. Promising tumor cell targets were identified in the cell membrane, cytoplasm and nucleus. New therapeutic approaches, besides monoclonal antibodies and vaccination, include an increasing number of small molecules that have been shown to interfere restrictively with intracellular signaling pathways in melanoma and decrease proliferation, survival, migration or invasion. Other agents can interfere with stromal components of melanoma, such as angiogenesis and components of the immune system.