Function but not phenotype of melanoma peptide-specific CD8(+) T cells correlate with survival in a multiepitope peptide vaccine trial (ECOG 1696)

Potential association factors for developing effective peptide-based cancer vaccines

Peptide-based cancer vaccines have been shown to boost immune systems to kill tumor cells in cancer patients. However, designing an effective T cell epitope peptide-based cancer vaccine still remains a challenge and is a major hurdle for the application of cancer vaccines. In this study, we constructed for the first time a library of peptide-based cancer vaccines and their clinical attributes, named CancerVaccine (https://peptidecancervaccine.weebly.com/). To investigate the association factors that influence the effectiveness of cancer vaccines, these peptide-based cancer vaccines were classified into high (HCR) and low (LCR) clinical responses based on their clinical efficacy. Our study highlights that modified peptides derived from artificially modified proteins are suitable as cancer vaccines, especially for melanoma. It may be possible to advance cancer vaccines by screening for HLA class II affinity peptides may be an effective therapeutic strategy. In addition, the treatment regimen has the potential to influence the clinical response of a cancer vaccine, and Montanide ISA-51 might be an effective adjuvant. Finally, we constructed a high sensitivity and specificity machine learning model to assist in designing peptide-based cancer vaccines capable of providing high clinical responses. Together, our findings illustrate that a high clinical response following peptide-based cancer vaccination is correlated with the right type of peptide, the appropriate adjuvant, and a matched HLA allele, as well as an appropriate treatment regimen. This study would allow for enhanced development of cancer vaccines.

Peripheral immune-based biomarkers in cancer immunotherapy: can we realize their predictive potential?

The immunologic landscape of the host and tumor play key roles in determining how patients will benefit from immunotherapy, and a better understanding of these factors could help inform how well a tumor responds to treatment. Recent advances in immunotherapy and in our understanding of the immune system have revolutionized the treatment landscape for many advanced cancers. Notably, the use of immune checkpoint inhibitors has demonstrated durable responses in various malignancies. However, the response to such treatments is variable and currently unpredictable, the availability of predictive biomarkers is limited, and a substantial proportion of patients do not respond to immune checkpoint therapy. Identification and investigation of potential biomarkers that may predict sensitivity to immunotherapy is an area of active research. It is envisaged that a deeper understanding of immunity will aid in harnessing the full potential of immunotherapy, and allow appropriate patients to receive the most appropriate treatments. In addition to the identification of new biomarkers, the platforms and assays required to accurately and reproducibly measure biomarkers play a key role in ensuring consistency of measurement both within and between patients. In this review we discuss the current knowledge in the area of peripheral immune-based biomarkers, drawing information from the results of recent clinical studies of a number of different immunotherapy modalities in the treatment of cancer, including checkpoint inhibitors, bispecific antibodies, chimeric antigen receptor T cells, and anti-cancer vaccines. We also discuss the various technologies and approaches used in detecting and measuring circulatory biomarkers and the ongoing need for harmonization.

Existing and Emerging Biomarkers for Immune Checkpoint Immunotherapy in Solid Tumors

In the last few years, immunotherapy has transformed the way we treat solid tumors, including melanoma, lung, head neck, breast, renal, and bladder cancers. Durable responses and long-term survival benefit has been experienced by many cancer patients, with favorable toxicity profiles of immunotherapeutic agents relative to chemotherapy. Cures have become possible in some patients with metastatic disease. Additional approvals of immunotherapy drugs and in combination with other agents are anticipated in the near future. Multiple additional immunotherapy drugs are in earlier stages of clinical development, and their testing in additional tumor types is under way. Despite considerable early success and relatively fewer side effects, the majority of cancer patients do not respond to checkpoint inhibitors. Additionally, while the drugs are generally well tolerated, there is still the potential for significant, unpredictable and even fatal toxicity with these agents. Improved biomarkers may help to better select patients who are more likely to respond to these drugs. Two key biologically important predictive tissue biomarkers, specifically, PD-L1 and mismatch repair deficiency, have been FDA-approved in conjunction with the checkpoint inhibitor, pembrolizumab. Tumor mutation burden, another promising biomarker, is emerging in several tumor types, and may also soon receive approval. Finally, several other tissue and liquid biomarkers are emerging that could help guide single-agent immunotherapy and in combination with other agents. Of these, one promising investigational biomarker is alteration or deficiency in DNA damage response (DDR) pathways, with altered DDR observed in a broad spectrum of tumors. Here, we provide a critical overview of current, emerging, and investigational biomarkers in the context of response to immunotherapy in solid tumors.

Prognostic biomarkers for immunotherapy with ipilimumab in metastatic melanoma

New therapies, including the anti‐cytotoxic T lymphocyte antigen (CTLA)‐4 antibody, ipilimumab, is approved for metastatic melanoma. Prognostic biomarkers need to be identified, because the treatment has serious side effects. Serum samples were obtained before and during treatment from 56 patients with metastatic or unresectable malignant melanoma, receiving treatment with ipilimumab in a national Phase IV study (NCT0268196). Expression of a panel of 17 inflammatory‐related markers reflecting different pathways including extracellular matrix remodeling and fibrosis, vascular inflammation and monocyte/macrophage activation were measured at baseline and the second and/or third course of treatment with ipilimumab. Six candidate proteins [endostatin, osteoprotegerin (OPG), C‐reactive protein (CRP), pulmonary and activation‐regulated chemokine (PARC), growth differentiation factor 15 (GDF15) and galectin‐3 binding‐protein (Gal3BP)] were persistently higher in non‐survivors. In particular, high Gal3BP and endostatin levels were also independently associated with poor 2‐year survival after adjusting for lactate dehydrogenase, M‐stage and number of organs affected. A 1 standard deviation increase in endostatin gave 1·74 times [95% confidence interval (CI) = 1·10–2·78, P = 0·019] and for Gal3BP 1·52 times (95% CI = 1·01–2·29, P = 0·047) higher risk of death in the adjusted model. Endostatin and Gal3BP may represent prognostic biomarkers for patients on ipilimumab treatment in metastatic melanoma and should be further evaluated. Owing to the non‐placebo design, we could only relate our findings to prognosis during ipilimumab treatment.

Immune biomarkers for predicting response to adoptive cell transfer as cancer treatment

Adoptive cell transfer (ACT) is a form of personalised immunotherapy which has shown promising results in metastasised cancer. For this treatment, autologous T lymphocytes are selected and stimulated in vitro before re-administration in large numbers. However, only a fraction of patients benefit from ACT, and it is not yet known what biomarkers can predict treatment outcome. In this review, we describe what tumour characteristics are associated with response to ACT. Based on the current knowledge, the best candidate biomarker for a good anti-tumour response seems to be a large number of neoantigens with a homogeneous distribution across the tumour in combination with sufficient MHC-I expression level. Additionally, it is necessary to be able to isolate a diverse population of T cells reactive to these neoantigens from tumour tissue or peripheral blood. Additional promising candidate biomarkers shared with other cancer immunotherapies are a large number of tumour-infiltrating cytotoxic and memory T cells, normal levels of glycolysis, and a pro-inflammatory cytokine profile within the tumour. Intense research in this field will hopefully result in identification of more biomarkers for cancers with low mutational load.

Whole cell melanoma vaccine genetically modified to stem cells like phenotype generates specific immune responses to ALDH1A1 and long-term survival in advanced melanoma patients

Allogeneic whole cell gene modified therapeutic melanoma vaccine (AGI-101H) comprising of two melanoma cell lines transduced with cDNA encoding fusion protein composed of IL-6 linked with the soluble IL-6 receptor (sIL-6R), referred to as H6 was developed. H6 served as a molecular adjuvant, however, it has altered vaccine cells phenotype towards melanoma stem cells (MSC)-like with high activity of aldehyde dehydrogenase isoenzyme (ALDH1A1). AGI-101H was applied in advanced melanoma patients with non-resected and resected disease. In the adjuvant setting, it was combined with surgery in case of recurring metastases, which were surgically removed and vaccination continued. A significant fraction of AGI-101H treated melanoma patients is still alive (11–19 years). Out of 106 living patients, 39 were HLA-A2 positive and were the subject of the study. Immunization of melanoma patients resulted in the generation of cytotoxic CD8+ T cells specific for ALDH1A1, which were detected in circulation by HLA-A0201 MHC dextramers loaded with ALDH1A1_88-96(LLYKLADLI) peptide. Phenotypically they were central memory CD8⁺ T cells. Re-stimulation with ALDH1A1_88-96ex vivo resulted in IFN-γ secretion and cells degranulation. Following each vaccine dose administration, the number of ALDH1A1-CD8⁺ T cells increased in circulation and returned to the previous level until next dose injection (one month). ALDH1A1-CD8⁺ T cells were also found, however in the lower number than in vaccinated patients, in the circulation of untreated melanoma with stage IV but were not found in stage II or III and healthy donors. Specific anti-ALDH1 antibodies were present in treated patients. Long-term survival suggests immuno-targeting of MSC in treated patients.

Identifying baseline immune-related biomarkers to predict clinical outcome of immunotherapy

As cancer strikes, individuals vary not only in terms of factors that contribute to its occurrence and development, but as importantly, in their capacity to respond to treatment. While exciting new therapeutic options that mobilize the immune system against cancer have led to breakthroughs for a variety of malignancies, success is limited to a subset of patients. Pre-existing immunological features of both the host and the tumor may contribute to how patients will eventually fare with immunotherapy. A broad understanding of baseline immunity, both in the periphery and in the tumor microenvironment, is needed in order to fully realize the potential of cancer immunotherapy. Such interrogation of the tumor, blood, and host immune parameters prior to treatment is expected to identify biomarkers predictive of clinical outcome as well as to elucidate why some patients fail to respond to immunotherapy. To approach these opportunities for progress, the Society for Immunotherapy of Cancer (SITC) reconvened the Immune Biomarkers Task Force. Comprised of an international multidisciplinary panel of experts, Working Group 4 sought to make recommendations that focus on the complexity of the tumor microenvironment, with its diversity of immune genes, proteins, cells, and pathways naturally present at baseline and in circulation, and novel tools to aid in such broad analyses.

Unraveling the role of preexisting immunity in prostate cancer patients vaccinated with a HER-2/neu hybrid peptide

Background

Cancer vaccines aim at eliciting not only an immune response against specific tumor antigens, but also at enhancing a preexisting immunity against the tumor. In this context, we recently reported on the levels of preexisting immunity in prostate cancer patients vaccinated with the HER-2 hybrid peptide (AE37), during a phase I clinical trial. The purpose of the current study was to correlate between preexisting immunity to the native HER-2 peptide, AE36, and expression of HLA-A2 and -A24 molecules with the clinical outcome. Additionally, we investigated the ability of the AE37 vaccine to induce an antitumor immune response against other tumor associated antigens, not integrated in the vaccine formulation, with respect to the clinical response.

Methods

We analyzed prostate cancer patients who were vaccinated with the AE37 vaccine [Ii-Key-HER-2/neu_(776–790) hybrid peptide vaccine (AE37), which is a MHC class II long peptide vaccine encompassing MHC class I epitopes, during a phase I clinical trial. Preexisting immunity to the native HER-2/neu_(776–790) (AE36) peptide was assessed by IFNγ response or dermal reaction at the inoculation site. Antigen specificity against other tumor antigens was defined using multimer analysis. Progression free survival (PFS) was considered as the patients’ clinical outcome. Two-tailed Wilcoxon signed rank test at 95 % confidence interval was used for statistical evaluation at different time points and Kaplan–Meier curves with log-rank (Mantel-Cox) test were used for the evaluation of PFS.

Results

Preexisting immunity to AE36, irrespectively of HLA expression, was correlated with longer PFS. Specific CD8⁺ T cell immunity against E75 and PSA_146–151 (HLA-A2 restricted), as well as, PSA_153–161 (HLA-A24 restricted) was detected at relatively high frequencies which were further enhanced during vaccinations. Specific immunity against PSA_153–161 correlated with longer PFS in HLA-A24⁺ patients. However, HLA-A2⁺ patients with high preexisting or vaccine-induced immunity to E75, showed a trend for shorter PFS.

Conclusions

Our data cast doubt on whether preexisting immunity or epitope spreading specific for HLA-class I-restricted peptides can actually predict a favorable clinical outcome. They also impose that preexisting immunity to long vaccine peptides, encompassing both HLA class II and I epitopes should be considered as an important prerequisite for the improvement of future immunotherapeutic protocols.

Protocol ID Code: Generex-06-07

National Organization for Medicines (EOF) ID Code: IS-107-01-06

NEC Study Code: EED107/1/06

EudraCT Number: 2006-003299-37

Date of registration: 07/06/2006

Date of enrolment of the first participant to the trial: Nov 1st, 2007

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-016-0183-4) contains supplementary material, which is available to authorized users.

Phase I study to evaluate toxicity and feasibility of intratumoral injection of α-gal glycolipids in patients with advanced melanoma

Effective uptake of tumor cell-derived antigens by antigen-presenting cells is achieved pre-clinically by in situ labeling of tumor with α-gal glycolipids that bind the naturally occurring anti-Gal antibody. We evaluated toxicity and feasibility of intratumoral injections of α-gal glycolipids as an autologous tumor antigen-targeted immunotherapy in melanoma patients (pts). Pts with unresectable metastatic melanoma, at least one cutaneous, subcutaneous, or palpable lymph node metastasis, and serum anti-Gal titer ≥1:50 were eligible for two intratumoral α-gal glycolipid injections given 4 weeks apart (cohort I: 0.1 mg/injection; cohort II: 1.0 mg/injection; cohort III: 10 mg/injection). Monitoring included blood for clinical, autoimmune, and immunological analyses and core tumor biopsies. Treatment outcome was determined 8 weeks after the first α-gal glycolipid injection. Nine pts received two intratumoral injections of α-gal glycolipids (3 pts/cohort). Injection-site toxicity was mild, and no systemic toxicity or autoimmunity could be attributed to the therapy. Two pts had stable disease by RECIST lasting 8 and 7 months. Tumor nodule biopsies revealed minimal to no change in inflammatory infiltrate between pre- and post-treatment biopsies except for 1 pt (cohort III) with a post-treatment inflammatory infiltrate. Two and four weeks post-injection, treated nodules in 5 of 9 pts exhibited tumor cell necrosis without neutrophilic or lymphocytic inflammatory response. Non-treated tumor nodules in 2 of 4 evaluable pts also showed necrosis. Repeated intratumoral injections of α-gal glycolipids are well tolerated, and tumor necrosis was seen in some tumor nodule biopsies after tumor injection with α-gal glycolipids.

Adjuvant Autologous Melanoma Vaccine for Macroscopic Stage III Disease: Survival, Biomarkers, and Improved Response to CTLA-4 Blockade

Background. There is not yet an agreed adjuvant treatment for melanoma patients with American Joint Committee on Cancer stages III B and C. We report administration of an autologous melanoma vaccine to prevent disease recurrence. Patients and Methods. 126 patients received eight doses of irradiated autologous melanoma cells conjugated to dinitrophenyl and mixed with BCG. Delayed type hypersensitivity (DTH) response to unmodified melanoma cells was determined on the vaccine days 5 and 8. Gene expression analysis was performed on 35 tumors from patients with good or poor survival. Results. Median overall survival was 88 months with a 5-year survival of 54%. Patients attaining a strong DTH response had a significantly better (p = 0.0001) 5-year overall survival of 75% compared with 44% in patients without a strong response. Gene expression array linked a 50-gene signature to prognosis, including a cluster of four cancer testis antigens: CTAG2 (NY-ESO-2), MAGEA1, SSX1, and SSX4. Thirty-five patients, who received an autologous vaccine, followed by ipilimumab for progressive disease, had a significantly improved 3-year survival of 46% compared with 19% in nonvaccinated patients treated with ipilimumab alone (p = 0.007). Conclusion. Improved survival in patients attaining a strong DTH and increased response rate with subsequent ipilimumab suggests that the autologous vaccine confers protective immunity.

Intratumoral delivery of mTORC2-deficient dendritic cells inhibits B16 melanoma growth by promoting CD8(+) effector T cell responses

Dendritic cells (DC) play a pivotal role in the induction and regulation of immune responses. In cancer, DC-based vaccines have proven to be safe and to elicit protective and therapeutic immunological responses. Recently, we showed that specific mTORC2 (mechanistic target of rapamycin complex 2) deficiency in DC enhances their ability to promote Th1 and Th17 responses after LPS stimulation. In the present study, bone marrow-derived mTORC2-deficient (Rictor(-/-)) DC were evaluated as a therapeutic modality in the murine B16 melanoma model. Consistent with their pro-inflammatory profile (enhanced IL-12p70 production and low PD-L1 expression versus control DC), intratumoral (i.t.) injection of LPS-activated Rictor(-/-) DC slowed B16 melanoma growth markedly in WT C57BL/6 recipient mice. This antitumor effect was abrogated when Rictor(-/-) DC were injected i.t. into B16-bearing Rag(-/-) mice, and also after selective CD8(+) T cell depletion in wild-type hosts in vivo, indicating that CD8(+) T cells were the principal regulators of tumor growth after Rictor(-/-) DC injection. I.t. administration of Rictor(-/-) DC also reduced the frequency of myeloid-derived suppressor cells within tumors, and enhanced numbers of IFNγ(+) and granzyme-B(+) cytotoxic CD8(+) T cells both in the spleens and tumors of treated animals. These data suggest that selective inhibition of mTORC2 activity in activated DC augments their pro-inflammatory and T cell stimulatory profile, in association with their enhanced capacity to promote protective CD8(+) T cell responses in vivo, leading to slowed B16 melanoma progression. These novel findings may contribute to the design of more effective DC-based vaccines for cancer immunotherapy.

Dendritic cell-based autologous tumor vaccines for head and neck squamous cell carcinoma

BACKGROUND

An autologous vaccine of apoptotic tumor cells (ATCs) and dendritic cells (DCs) was administered to patients with stage III/IV head and neck squamous cell carcinoma (HNSCC) to study safety and feasibility.

METHODS

Autologous DCs were generated from monocytes, loaded with ATCs, and delivered intranodally. Delayed-type hypersensitivity (DTH) and immunological endpoints were measured prevaccination and postvaccination. Clinical follow-up was required.

RESULTS

Tumors obtained from 30 patients yielded 2 × 10(6) to 2 × 10(8) tumor cells. Only 19 of 30 (63%) were sterile. Ten of 30 patients (33%) had ≥1 × 10(7) sterile tumor cells required for vaccine production. Eight of 10 patients had positive recall DTH. Five of 10 patients were leukapheresed to generate DCs. Four of 5 patients were vaccinated. ATC-reactive T cells were detected in 3 of 4 patients. All 4 patients survived >5 years. The trial failed to enroll the projected 12 patients and was terminated.

CONCLUSION

This vaccine was safe and immunogenic but feasible only in patients with HNSCC with positive prevaccine DTH and ≥1 × 10(7) sterile tumor cells. All vaccinated patients were long-term disease-free survivors. © 2015 Wiley Periodicals, Inc. Head Neck 38: E494-E501, 2016.

Cancer vaccines

Cancer vaccines are designed to promote tumor specific immune responses, particularly cytotoxic CD8 positive T cells that are specific to tumor antigens. The earliest vaccines, which were developed in 1994-95, tested non-mutated, shared tumor associated antigens that had been shown to be immunogenic and capable of inducing clinical responses in a minority of people with late stage cancer. Technological developments in the past few years have enabled the investigation of vaccines that target mutated antigens that are patient specific. Several platforms for cancer vaccination are being tested, including peptides, proteins, antigen presenting cells, tumor cells, and viral vectors. Standard of care treatments, such as surgery and ablation, chemotherapy, and radiotherapy, can also induce antitumor immunity, thereby having cancer vaccine effects. The monitoring of patients' immune responses at baseline and after standard of care treatment is shedding light on immune biomarkers. Combination therapies are being tested in clinical trials and are likely to be the best approach to improving patient outcomes.

Tumor lysate-loaded biodegradable microparticles as cancer vaccines

Cancer vaccines that use tumor lysate (TL) as a source of tumor-associated antigens (TAAs) have significant potential for generating therapeutic anti-tumor immune responses. Vaccines encompassing TL bypass the limitations of single antigen vaccines by simultaneously stimulating immunity against multiple TAAs, thereby broadening the repertoire of TAA-specific T-cell clones available for activation. Administration of TL in particulate form, such as when encapsulated in biodegradable microparticles, increases its immunostimulatory capacity and produces more robust immune responses than when TL is given in soluble form. These effects can be further enhanced by co-administering TL with adjuvants. A number of recent studies using polymeric microparticle delivery of TL, with or without adjuvants, have produced promising results in preclinical studies. In this review, we will discuss current experimental approaches involving TL being pursued in the oncoimmunology field, and comment on strategies such as combining specific chemotherapeutic agents with TL microparticle delivery that may eventually lead to improved survival outcomes for cancer patients.

Current status of granulocyte-macrophage colony-stimulating factor in the immunotherapy of melanoma

In 2012, it was estimated that 9180 people in the United States would die from melanoma and that more than 76,000 new cases would be diagnosed. Surgical resection is effective for early-stage melanoma, but outcomes are poor for patients with advanced disease. Expression of tumor-associated antigens by melanoma cells makes the disease a promising candidate for immunotherapy. The hematopoietic cytokine granulocyte–macrophage colony-stimulating factor (GM-CSF) has a variety of effects on the immune system including activation of T cells and maturation of dendritic cells, as well as an ability to promote humoral and cell-mediated responses. Given its immunobiology, there has been interest in strategies incorporating GM-CSF in the treatment of melanoma. Preclinical studies with GM-CSF have suggested that it has antitumor activity against melanoma and can enhance the activity of anti-melanoma vaccines. Numerous clinical studies have evaluated recombinant GM-CSF as a monotherapy, as adjuvant with or without cancer vaccines, or in combination with chemotherapy. Although there have been suggestions of clinical benefit in some studies, results have been inconsistent. More recently, novel approaches incorporating GM-CSF in the treatment of melanoma have been evaluated. These have included oncolytic immunotherapy with the GM-CSF–expressing engineered herpes simplex virus talimogene laherparepvec and administration of GM-CSF in combination with ipilimumab, both of which have improved patient outcomes in phase 3 studies. This review describes the diverse body of preclinical and clinical evidence regarding use of GM-CSF in the treatment of melanoma.

Immunologic monitoring of cancer vaccine trials using the ELISPOT assay

Cancer vaccines are designed to activate an immune response to tumor-specific or tumor-associated antigens expressed by the tumor. Cancer vaccines take many forms, including synthetic peptides, tumor cells and lysates, cell lines, and autologous antigen presenting cells like dendritic cells. The target antigens may be known, or "defined" in the vaccine, or unknown. In melanoma, more so than in other cancers, a large number of immunogenic "shared" antigens (tumor-specific or tumor-associated) have been identified. This allows for vaccination of groups of patients with the same vaccine, and also allows for testing for melanoma tumor immunity even when the vaccine does not include defined antigens. For the cancer vaccine field, the goal of a prognostic or predictive biomarker has yet to be achieved. However, the primary immunologic goal of any cancer vaccine is the induction (or amplification) of an immune response against the tumor, therefore the primary goal of immunologic monitoring in this setting, is testing for that response. In this chapter, we present standardized methodology from a central immunologic monitoring laboratory for melanoma cancer vaccine immune response assessment by the Enzyme-Linked Immunosorbant Spot (ELISPOT) assay. This assay allows for enumeration of antigen-specific cells in a plate format. We present the Interferon (IFN)-γ-producing lymphocyte assay, but the platform is easily adjusted to several cell types and several secreted molecules.

Recent progress in peptide vaccination in cancer with a focus on non-small-cell lung cancer

Active immunotherapy aimed at the stimulation of tumor-specific T cells has established itself within the clinic as a therapeutic option to treat cancer. One strategy is the use of so-called peptides that mimic genuine T-cell epitopes as vaccines to activate tumor-specific T cells. In various clinical trials, different types of vaccines, adjuvants and other immunomodulatory compounds were evaluated in patients with different types of tumors. Here, we review the trials published in the last 3 years focusing on the T-cell response, the effect of immunomodulation and potential relationships with clinical outcomes. Furthermore, we would like to make a case for the development of peptide vaccines aiming to treat non-small-cell lung cancer, the most common cause of cancer mortality.

Ex vivo derived primary melanoma cells: implications for immunotherapeutic vaccines

Transformation of the pigment producing melanocytes into melanoma is a complex multi-step process involving the enhanced expression of various antigens considered as immunotherapeutic targets. Significant progress in melanoma research has been made over the years and has resulted in the identification of various antigens over expressed in melanoma as well as advances in immunotherapeutic treatments, which focus on modulating the immune systems response to melanoma. Despite these advances, incidences of melanoma are still on the rise thus warranting additional research in identifying new therapeutic treatments. Our focus is on developing a multivalent immunotherapeutic vaccine that targets various melanoma associated antigens. The approach focuses on the use of five primary patient derived melanoma cells (MEL-2, MEL-V, 3MM, KFM, and GLM-2, which have been characterized in this study. These cells express differential amounts of various melanoma associated antigens such as MART-1, gp100 (Pmel17), MAGE-A1 and tyrosinase as well a cell surface antigens essential for melanoma cell metastasis, such as CD146 and CD71. In addition these cells display differential in vitro migratory and invasive properties as well as have the ability to form solid tumors when implanted into BALB/c nude mice. The retention of the innate phenotype of these primary patient derived cells together with the expression of a multitude repertoire of melanoma associated antigens offers a novel opportunity to target melanoma so as to avoid immune evasion.

Prospects of combinatorial synthetic peptide vaccine-based immunotherapy against cancer

The insight that the immune system is involved in tumor resistance is gaining momentum and this has led to the development of immunotherapeutic strategies aiming at enhancement of immune-mediated tumor destruction. Although some of these strategies have moderate clinical benefit, most stand-alone therapies fail to significantly affect progressive disease and survival or do so only in a minority of patients. Research on the mechanisms underlying the generation of immune responses against tumors and the immune evasion by tumors has emphasized that various mechanisms simultaneously prevent effective immunity against cancer including inefficient presentation of tumor antigens by dendritic cells and induction of negative immune regulation by regulatory T-cells (Tregs) and myeloid derived suppressor cells (MDSCs). Thus the design of therapies that simultaneously improve effective tumor immunity and counteract immune evasion by tumors seems most desirable for clinical efficacy. As it is unlikely that a single immunotherapeutic strategy addresses all necessary requirements, combinatorial strategies that act synergistically need to be developed. Here we discuss the current knowledge and prospects of treatment with synthetic peptide vaccines that stimulate tumor-specific T-cell responses combined with adjuvants, immune modulating antibodies, cytokines and chemotherapy. We conclude that combinatorial approaches have the best potency to accomplish the most significant tumor destruction but further research is required to optimize such approaches.

Immune responses to cancer: are they potential biomarkers of prognosis?

Recent technical improvements in evaluations of immune cells in situ and immune monitoring of patients with cancer have provided a wealth of new data confirming that immune cells play a key role in human cancer progression. This, in turn, has revived the expectation that immune endpoints might serve as reliable biomarkers of outcome or response to therapy in cancer. The recent successes in linking the T-cell signature in human colorectal carcinoma (CRC) with prognosis have provided a strong motive for searching for additional immune biomarkers that could serve as intermediate endpoints of response to therapy and outcome in human cancers. A number of potentially promising immune biomarkers have emerged, but most remain to be validated. Among them, the B-cell signature, as exemplified by expression of the immunoglobulin G kappa chain (IGKC) in tumor-infiltrating lymphocytes (TIL), has been validated as a biomarker of response to adjuvant therapy and better survival in patients with breast carcinoma and several other types of human solid tumors. Additional immune endpoints are being currently tested as potentially promising biomarkers in cancer. In view of currently growing use of immune cancer therapies, the search for immune biomarkers of prognosis are critically important for identifying patients who would benefit the most from adjuvant immunotherapy.

Biomarkers and correlative endpoints for immunotherapy trials

Immunotherapies for lung cancer are reaching phase III clinical trial, but the ultimate success likely will depend on developing biomarkers to guide development and choosing patient populations most likely to benefit. Because the immune response to cancer involves multiple cell types and cytokines, some spatially and temporally separated, it is likely that multiple biomarkers will be required to fully characterize efficacy of the vaccine and predict eventual benefit. Peripheral blood markers of response, such as the ELISPOT assay and cytokine flow cytometry analyses of peripheral blood mononuclear cells following immunotherapy, remain the standard approach, but it is increasingly important to obtain tissue to study the immune response at the site of the tumor. Earlier clinical endpoints such as response rate and progression-free survival do not correlate with overall survival demonstrated for some immunotherapies, suggesting the need to develop other intermediary clinical endpoints. Insofar as all these biomarkers and surrogate endpoints are relevant in multiple malignancies, it may be possible to extrapolate findings to immunotherapy of lung cancer.