Inhibition of tumor growth with antiangiogenic cancer vaccine using epitope peptides derived from human vascular endothelial growth factor receptor 1

Phase I/II Study of a Vascular Endothelial Growth Factor Receptor Vaccine in Patients With NF2-Related Schwannomatosis

PURPOSE

The humanized antivascular endothelial growth factor (VEGF) antibody bevacizumab (Bev) is efficacious for the treatment of NF2-related schwannomatosis (NF2), previously known as neurofibromatosis type 2. This study evaluated the safety and efficacy of a VEGF receptor (VEGFR) vaccine containing VEGFR1 and VEGFR2 peptides in patients with NF2 with progressive schwannomas (jRCTs031180184).

MATERIALS AND METHODS

VEGFR1 and VEGFR2 peptides were injected subcutaneously into infra-axillary and inguinal regions, once a week for 4 weeks and then once a month for 4 months. The primary end point was safety. Secondary end points included tolerability, hearing response, imaging response, and immunologic response.

RESULTS

Sixteen patients with NF2 with progressive schwannomas completed treatment and were assessed. No severe vaccine-related adverse events occurred. Among the 13 patients with assessable hearing, word recognition score improved in five patients at 6 months and two at 12 months. Progression of average hearing level of pure tone was 0.168 dB/mo during the year of treatment period, whereas long-term progression was 0.364 dB/mo. Among all 16 patients, a partial response was observed in more than one schwannoma in four (including one in which Bev had not been effective), minor response in 5, and stable disease in 4. Both VEGFR1-specific and VEGFR2-specific cytotoxic T lymphocytes (CTLs) were induced in 11 patients. Two years after vaccination, a radiologic response was achieved in nine of 20 assessable schwannomas.

CONCLUSION

This study demonstrated the safety and preliminary efficacy of VEGFR peptide vaccination in patients with NF2. Memory-induced CTLs after VEGFR vaccination may persistently suppress tumor progression.

Anticancer Peptides Derived from Aldolase A and Induced Tumor-Suppressing Cells Inhibit Pancreatic Ductal Adenocarcinoma Cells

PDAC (pancreatic ductal adenocarcinoma) is a highly aggressive malignant tumor. We have previously developed induced tumor-suppressing cells (iTSCs) that secrete a group of tumor-suppressing proteins. Here, we examined a unique procedure to identify anticancer peptides (ACPs), using trypsin-digested iTSCs-derived protein fragments. Among the 10 ACP candidates, P04 (IGEHTPSALAIMENANVLAR) presented the most efficient anti-PDAC activities. P04 was derived from aldolase A (ALDOA), a glycolytic enzyme. Extracellular ALDOA, as well as P04, was predicted to interact with epidermal growth factor receptor (EGFR), and P04 downregulated oncoproteins such as Snail and Src. Importantly, P04 has no inhibitory effect on mesenchymal stem cells (MSCs). We also generated iTSCs by overexpressing ALDOA in MSCs and peripheral blood mononuclear cells (PBMCs). iTSC-derived conditioned medium (CM) inhibited the progression of PDAC cells as well as PDAC tissue fragments. The inhibitory effect of P04 was additive to that of CM and chemotherapeutic drugs such as 5-Flu and gemcitabine. Notably, applying mechanical vibration to PBMCs elevated ALDOA and converted PBMCs into iTSCs. Collectively, this study presented a unique procedure for selecting anticancer P04 from ALDOA in an iTSCs-derived proteome for the treatment of PDAC.

CRISPR/Cas9-mediated mutations in both a cAMP response element and an ETS-binding site suppress FLT1 gene expression

The Fms-like tyrosine kinase-1 (FLT1) gene is expressed in various types of cells, including vascular endothelial cells and placental trophoblasts, and regulates angiogenesis, inflammation, and pregnancy. However, the basal transcriptional machinery of FLT1 is still not well understood. In this study, we first examined FLT1 promoter activity in three different types of cells, that is, trophoblast-derived cells, vascular endothelial-related cells, and HEK293 cells, using plasmid-based luciferase reporter assays, and showed that a cAMP-response element (CRE) and an ETS-binding site (EBS) are important for FLT1 expression in all cell types. To further examine the importance of these sites at the chromosomal level using HEK293 cells, we introduced CRISPR/Cas9-mediated mutations in these sites on the genomic DNA. HEK293 cells carrying these mutations clearly showed a significant decrease in endogenous FLT1 gene expression. These results suggest that CRE and EBS transcription regulatory elements are crucial for FLT1 gene expression in human tissues.

Current Targeted Therapy for Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the third most common type of cancer and the second leading cause of cancer deaths worldwide. Surgery or surgery plus radiotherapy and/or chemotherapy for patients with metastatic CRC (mCRC) were accepted as the main therapeutic strategies until the early 2000s, when targeted drugs, like cetuximab and bevacizumab, were developed. The use of targeted drugs in clinical practice has significantly increased patients' overall survival. To date, the emergence of several types of targeted drugs has opened new possibilities and revealed new prospects for mCRC treatment. Therapeutic strategies are continually being updated to select the most suitable targeted drugs based on the results of clinical trials that are currently underway. This review discusses the up-to date molecular evidence of targeted therapy for mCRC and summarizes the Food and Drug Administration-approved targeted drugs including the results of clinical trials. We also explain their mechanisms of action and how these affect the choice of a suitable targeted therapy.

Vaccines targeting angiogenesis in melanoma

Angiogenesis has a significant role in metastasis and progression of melanoma. Even small tumors may be susceptible to metastasis and hence lead to a worse outcome in patients with melanoma. One of the anti-angiogenic treatment approaches that is undergoing comprehensive study is specific immunotherapy. While tumor cells are challenging targets for immunotherapy due to their genetic instability and heterogeneity, endothelial cells (ECs) are genetically stable. Therefore, vaccines targeting angiogenesis in melanoma are appropriate choices that target both tumor cells and ECs while capable of inducing strong, anti-tumor immune responses with limited toxicity. The main targets of angiogenesis are VEGFs and their receptors but other potential targets have also been investigated, especially in preclinical studies. Various types of vaccines that target angiogenesis in melanoma have been studied including DNA, peptide, protein, dendritic cell-based, and endothelial cell vaccines. This review outlines a number of target antigens that are important for potential progress in developing vaccines for targeting angiogenesis in melanoma. We also discuss different types of vaccines that have been investigated, delivery mechanisms and popular adjuvants, and suggest ways to improve future clinical outcomes.

Improved Immunotherapy Efficacy by Vascular Modulation

Several strategies have been developed to modulate the tumour vasculature for cancer therapy including anti-angiogenesis and vascular normalisation. Vasculature modulation results in changes to the tumour microenvironment including oxygenation and immune cell infiltration, therefore lending itself to combination with cancer therapy. The development of immunotherapies has led to significant improvements in cancer treatment. Particularly promising are immune checkpoint blockade and CAR T cell therapies, which use antibodies against negative regulators of T cell activation and T cells reprogrammed to better target tumour antigens, respectively. However, while immunotherapy is successful in some patients, including those with advanced or metastatic cancers, only a subset of patients respond. Therefore, better predictors of patient response and methods to overcome resistance warrant investigation. Poor, or periphery-limited, T cell infiltration in the tumour is associated with poor responses to immunotherapy. Given that (1) lymphocyte recruitment requires leucocyte-endothelial cell adhesion and (2) the vasculature controls tumour oxygenation and plays a pivotal role in T cell infiltration and activation, vessel targeting strategies including anti-angiogenesis and vascular normalisation in combination with immunotherapy are providing possible new strategies to enhance therapy. Here, we review the progress of vessel modulation in enhancing immunotherapy efficacy.

Immunotherapeutic advances in gastric cancer

Advanced gastric cancers are responsible for overwhelming human suffering and death. Despite the development of combination chemotherapies, the survival rates of patients with gastric cancer remain unsatisfactory. Given the growing evidence of the benefits of immunotherapy as an alternative treatment for other cancers such as advanced melanoma, non-small cell lung cancer, renal cell carcinoma, and refractory Hodgkin's lymphoma, researchers have begun to explore its application in the treatment of gastric cancer. Three types of immunotherapy have shown promising effects against gastric cancer: immune checkpoint inhibitors, chimeric antigen rector (CAR)-T cells, and tumor vaccines. Clinical trials have used either immuno-oncology monotherapies or combination immuno-chemotherapies to improve the overall survival times and objective response rates of patients with gastric cancer. We review the clinical efficacy of immunotherapy including checkpoint inhibitors, CAR‑T, and tumor vaccines, in the treatment of gastric cancer. Based on initial evidence, we believe that immunotherapy could positively impact the natural history and improve the outcomes of a subgroup of patients with gastric cancer.

Siglec-7 is a predictive biomarker for the efficacy of cancer vaccination against metastatic colorectal cancer

Cancer immunotherapy, including vaccination, is considered a major scientific and medical breakthrough. However, cancer immunotherapy does not result in durable objective responses against colorectal cancer (CRC). To improve the efficacy of immunotherapy, the present study investigated several biomarkers for selecting patients who were expected to respond well to immunotherapy. Firstly, a comprehensive proteomic analysis was performed using tumor tissue lysates from patients enrolled in a phase II study, in which five human leukocyte antigen (HLA)-A*24:02-restricted peptides were administered. Sialic acid-binding immunoglobulin type lectin (Siglec)-7 was identified as a potential predictive biomarker. Subsequently, this biomarker was validated using western blot analysis, and immunofluorescence using tissue samples from the patients enrolled in the phase II study. The expression levels of Siglec-7 detected by immunofluorescence were quantified and their association with overall survival (OS) in patients treated with the peptide vaccine was examined. Furthermore, considering the important role of tumor-infiltrating lymphocytes (TILs) for CRC prognosis, the densities of CD3⁺, CD4^+, CD8⁺ and forkhead box P3 (FOXP3)⁺ T cells in CRC tissues were examined and compared with Siglec-7 expression. The mean expression levels of Siglec-7 were significantly higher in patients with poor prognosis, with an OS of ≤2 years, as shown in comprehensive proteomic analysis (P=0.016) and western blot analysis (P=0.025). Immunofluorescence analysis demonstrated that Siglec-7 was expressed in intratumoral macrophages. The OS in patients with high Siglec-7 expression was significantly shorter than in that in patients with low Siglec-7 expression (P=0.017) in the HLA-A*24:02-matched patients. However, this difference was not observed in the HLA-unmatched patients. There was no significant difference in OS between patients according to the numbers of TILs, nor significant correlation between TILs and Siglec-7 expression. In conclusion, Siglec-7 expression in macrophages in tumor tissue may be a novel predictive biomarker for the efficacy of immunotherapy against metastatic CRC.

Inhibiting Autophagy in Renal Cell Cancer and the Associated Tumor Endothelium

The clear cell subtype of kidney cancer encompasses most renal cell carcinoma cases and is associated with the loss of von Hippel-Lindau gene function or expression. Subsequent loss or mutation of the other allele influences cellular stress responses involving nutrient and hypoxia sensing. Autophagy is an important regulatory process promoting the disposal of unnecessary or degraded cellular components, tightly linked to almost all cellular processes. Organelles and proteins that become damaged or that are no longer needed in the cell are sequestered and digested in autophagosomes upon fusing with lysosomes, or alternatively, released via vesicular exocytosis. Tumor development tends to disrupt the regulation of the balance between this process and apoptosis, permitting prolonged cell survival and increased replication. Completed trials of autophagic inhibitors using hydroxychloroquine in combination with other anticancer agents including rapalogues and high-dose interleukin 2 have now been reported. The complex nature of autophagy and the unique biology of clear cell renal cell carcinoma warrant further understanding to better develop the next generation of relevant anticancer agents.

Clinical and histopathological analyses of VEGF receptors peptide vaccine in patients with primary glioblastoma - a case series

BACKGROUND

The expression of vascular endothelial growth factor (VEGF)-A/ VAGF receptors (VEGFRs) signaling plays a pivotal role in the tumor angiogenesis and the development of the immunosuppressive tumor microenvironment in glioblastomas. We have previously conducted exploratory clinical studies investigating VEGFRs peptide vaccination with and without multiple glioma oncoantigens in patients with recurrent high-grade gliomas. Recently, an exploratory clinical investigation of VEGFRs peptide vaccination was conducted in patients with progressive neurofibromatosis type 2. Those studies suggested that cytotoxic T lymphocytes (CTLs) induced by the vaccination can directly kill a wide variety of cells associated with tumor growth, including tumor vessels, tumor cells, and immunosuppressive cells expressing VEGFR1 and/or 2. In the present study, synergistic activity of the combination of VEGFRs peptide vaccination with chemotherapy was evaluated.

METHODS

We performed the first clinical trial to assess VEGFR1 and 2 vaccination along with temozolomide (TMZ) -based chemoradiotherapy for the patients with primary glioblastomas. Furthermore, histopathological changes after the vaccination were evaluated using paired pre- and post- vaccination specimens.

RESULTS

The disappearance of radiographically enhanced lesion was observed in 2 patients after the vaccination, including one in which the methylation of the O6-methylguanine-DNA methyltransferase (MGMT) promoter was not observed. The histopathological findings of pre- and post-vaccination specimens demonstrated that tumor vessels showed negative or slight VEGFRs expressions after the vaccination and most endothelial cells were covered with PDGFR-β-positive pericytes. Notably, CTLs induced by VEGFRs peptide vaccination attacked not only tumor vessels but also tumor cells and regulatory T cells expressing VEGFRs even in recurrent tumors.

CONCLUSIONS

VEGFR1 and 2 vaccination may have a preliminary synergistic effect when administered with TMZ. The limitation of the present study was the paucity of the number of the samples. Further studies involving more patients are warranted to confirm the findings of this study.

TRIAL REGISTRATION

This study was registered as UMIN000013381 (University Hospital Medical Information Network-Clinical Trial Registry: UMIN-CTR) on 5 March, 2014 and with the Japan Registry of Clinical Trials (jRCT) as jRCTs031180170 on 1 March, 2019.

A VEGF receptor vaccine demonstrates preliminary efficacy in neurofibromatosis type 2

The anti-VEGF antibody bevacizumab has shown efficacy for the treatment of neurofibromatosis type 2 (NF2). Theoretically, vascular endothelial growth factor receptors (VEGFRs)-specific cytotoxic T lymphocytes (CTLs) can kill both tumor vessel cells and tumor cells expressing VEGFRs. Here we show an exploratory clinical study of VEGFRs peptide vaccine in seven patients with progressive NF2-derived schwannomas. Hearing improves in 2/5 assessable patients (40%) as determined by international guidelines, with increases in word recognition scores. Tumor volume reductions of ≥20% are observed in two patients, including one in which bevacizumab had not been effective. There are no severe adverse events related to the vaccine. Both VEGFR1-specific and VEGFR2-specific CTLs are induced in six patients. Surgery is performed after vaccination in two patients, and significant reductions in the expression of VEGFRs in schwannomas are observed. Therefore, this clinical immunotherapy study demonstrates the safety and preliminary efficacy of VEGFRs peptide vaccination in patients with NF2.

The anti-vascular endothelial growth factor (VEGF) antibody bevacizumab has shown efficacy for the treatment of neurofibromatosis type 2 (NF2). Here, the authors show that VEGFRs peptide vaccination can improve hearing and reduce tumor volume in NF2 patients, including in previously bevacizumab resistant tumors.

Use of immunotherapy in the treatment of gastric cancer

Gastric cancer (GC) is a malignant tumor that negatively impacts human health, which typically presents in the advanced stages of disease in the majority of patients. Despite the development of combination chemotherapy, only a modest survival advantage is gained in patients with GC treated by this method. Recently, cancer immunotherapies have received considerable attention as a viable therapeutic option for GC. Specifically, the immune checkpoint inhibitors, chimeric antigen rector (CAR)-T cells and tumor vaccines, represent immunotherapies that have exhibited promising effects in the treatment of GC. A number of clinical trials have employed either immuno-oncology monotherapies or combination therapies to improve the overall survival time (OS) and objective response rate (ORR) of patients with GC. The current review presents a summary of the clinical effects of checkpoint inhibitors, including CAR-T and tumor vaccines, in the treatment of GC.

Targeting Angiogenesis With Peptide Vaccines

Most cancer peptide vaccinations tested so far are capable of eliciting a strong immune response, but demonstrate poor clinical benefits. Since peptide vaccination is safe and well-tolerated, and several indications suggest that it has clear potential advantages over other modalities of treatment, it is important to investigate the reasons for these clinical failures. In this review, the current state of the art in targeting angiogenic proteins via peptide vaccines is presented, and the underlying reasons for both the successes and the failures are analyzed. The review highlights a number of areas critical for future success, including choice of target antigens, types of peptides used, delivery methods and use of proper adjuvants, and suggests ways to achieve better clinical results in the future.

Limitations of Anti-Angiogenic Treatment of Tumors

Clinical trials using anti-vascular endothelial growth factor /(VEGF) molecules induce a modest improvement in overall survival, measurable in weeks to just a few months, and tumors respond differently to these agents. In this review article, we have exposed some tumor characteristics and processes that may impair the effectiveness of anti-angiogenic approaches, including genotypic changes on endothelial cells, the vascular normalization phenomenon, and the vasculogenic mimicry. The usage of anti-angiogenic molecules leads to hypoxic tumor microenvironment which enhances tumor invasiveness. The role of tumor-infiltrating cells, including tumor associated macrophages and fibroblasts (TAMs and TAFs) in the therapeutic response to anti-angiogenic settings was also highlighted. Finally, among the new therapeutic approaches to target tumor vasculature, anti-PD-1 or anti-PD-L1 therapy sensitizing and prolonging the efficacy of anti-angiogenic therapy, have been discussed.

Novel immunotherapeutic approaches for hepatocellular carcinoma treatment

INTRODUCTION

The introduction of immune checkpoint inhibitors has been lately proposed for the treatment of hepatocellular carcinoma (HCC) with respect to other cancer types. Several immunotherapeutic approaches are now under evaluation for HCC treatment including: i) antibodies acting as immune checkpoint inhibitors; ii) antibodies targeting specific tumor-associated antigens; iii) chimeric antigen receptor redirected T (CAR-T) cells targeting specific tumor-associated antigens; iv) vaccination strategies with tumor-specific epitopes. Areas covered: The review provides a wide description of the clinical trials investigating the efficacy of the main immunotherapeutic approaches proposed for the treatment of patients affected by HCC. Expert opinion: The balancing between immunostimulative and immunosuppressive factors in the context of HCC tumor microenvironment results in heterogeneous response rates to immunotherapeutic approaches such as checkpoint inhibitors, among HCC patients. In this context, it becomes crucial the identification of predictive factors determining the treatment response. A multiple approach using different biomarkers could be useful to identify the subgroup of HCC patients responsive to the treatment with a checkpoint inhibitor (as an example, nivolumab) as single agent, and to identify those patients in which other treatment regimens, such as the combination with sorafenib, or with locoregional therapies, could be more effective.

A Pilot Study of Vaccine Therapy with Multiple Glioma Oncoantigen/Glioma Angiogenesis-Associated Antigen Peptides for Patients with Recurrent/Progressive High-Grade Glioma

High-grade gliomas (HGGs) carry a dismal prognosis despite current treatments. We previously confirmed the safety and immunogenicity of a vaccine treatment targeting tumor angiogenesis with synthetic peptides, for vascular endothelial growth factor receptor (VEGFR) epitopes in recurrent HGG patients. In this study, we evaluated a novel vaccine therapy targeting not only tumor vasculature but also tumor cells, using multiple glioma oncoantigen (GOA)/glioma angiogenesis-associated antigen (GAAA) peptides in HLA-A2402+ recurrent/progressive HGG patients. The vaccine included peptide epitopes from four GOAs (LY6K, DEPDC1, KIF20A, and FOXM1) and two GAAAs (VEGFR1 and VEGFR2). Ten patients received subcutaneous vaccinations. The primary endpoint was the safety of the treatment. T-lymphocyte responses against GOA/GAAA epitopes and treatment response were evaluated secondarily. The treatment was well tolerated without any severe systemic adverse events. The vaccinations induced immunoreactivity to at least three vaccine-targeted GOA/GAAA in all six evaluable patients. The median overall survival time in all patients was 9.2 months. Five achieved progression-free status lasting at least six months. Two recurrent glioblastoma patients demonstrated stable disease. One patient with anaplastic oligoastrocytoma achieved complete response nine months after the vaccination. Taken together, this regimen was well tolerated and induced robust GOA/GAAA-specific T-lymphocyte responses in recurrent/progressive HGG patients.

Immune responses against tumour-associated antigen-derived cytotoxic T lymphocyte epitopes in cholangiocarcinoma patients

BACKGROUND & AIMS

Immunotherapy is a promising treatment option for cholangiocarcinoma. We compared cytotoxic T lymphocyte (CTL) responses against several tumour-associated antigen (TAA)-derived epitopes in cholangiocarcinoma patients to identify candidate epitopes for immunotherapy.

METHODS

Twenty-six TAAs were selected, and the expression of TAAs in 6 cholangiocarcinoma cell lines and 9 specimens were measured using real-time polymerase chain reaction (PCR). CTL responses against 38 TAA-derived epitopes were measured using samples from 26 cholangiocarcinoma patients by interferon-γ enzyme linked immunospot (ELISPOT)-assay.

RESULTS

Most TAAs were expressed in cholangiocarcinoma cell lines and specimens in PCR. Epitopes that stimulated a specific immune response were defined as those that elicited a CTL response in more than 3 patients and little response in healthy volunteers, as measured by ELISPOT-assay. Based on these criteria, there were 18 epitopes that stimulated specific immune responses: squamous cell carcinoma antigen recognized by T cells (SART)1₆₉₀ , P53₁₆₁ , multidrug resistance-associated protein (MRP)3₅₀₃ , Survivin2B₈₀ , melanoma-associated antigen (MAGE)-A4₁₄₃ , receptor tyrosine kinase ErbB-2/neu (Her2/neu)₆₃ , Wilms tumour (WT1)₂₃₅ , WT1₄₁₇ , β-catenin₂₉ , carcinoembryonic antigen (CEA)₂₆₈ , CEA₆₅₂ , epithelial cell adhesion molecule (EpCAM)₁₇₃ , enhancer of zeste homolog (EZH)2₂₉₁ , mucin 5AC (MUC5AC)₇₁₆ , glypican-3 (GPC3)₂₉₈ and kinesin family member 20A (KIF20A)₆₆ . Furthermore, the absolute number of lymphocytes in peripheral blood was significantly correlated with the TAA-specific response. Lastly, the overall survival was significantly prolonged in patients with 2 or more TAA-specific CTL responses compared with none to one.

CONCLUSIONS

These results demonstrated several TAAs may be promising for immunotherapy for cholangiocarcinoma, and patients with high lymphocyte counts may benefit more from immunotherapy.

A pilot study of peptide vaccines for VEGF receptor 1 and 2 in patients with recurrent/progressive high grade glioma

Object

Early-phase clinical studies of glioma vaccines have shown feasibility and encouraging preliminary clinical activity. A vaccine that targets tumor angiogenesis factors in glioma microenvironment has not been reported. Therefore, we performed a pilot study to evaluate the safety and immunogenicity of a novel vaccination targeting tumor angiogenesis with synthetic peptides for vascular endothelial growth factor (VEGF) receptor epitopes in patients with recurrent/progressive high grade gliomas.

Methods

Eight patients received intranodal vaccinations weekly at a dose of 2mg/kg bodyweight 8 times. T-lymphocyte responses against VEGF receptor (VEGFR) epitopes were assessed by enzyme linked immunosorbent spot assays.

Results

This treatment was well-tolerated in patients. The first four vaccines induced positive immune responses against at least one of the targeted VEGFR epitopes in the peripheral blood mononuclear cells in 87.5% of patients. The median overall survival time in all patients was 15.9 months. Two achieved progression-free status lasting at least 6 months. Two patients with recurrent GBM demonstrated stable disease. Plasma IL-8 level was negatively correlated with overall survival.

Conclusion

These data demonstrate the safety and immunogenicity of VEGFR peptide vaccines targeting tumor vasculatures in high grade gliomas.

miR-125b-1 and miR-378a are predictive biomarkers for the efficacy of vaccine treatment against colorectal cancer

Many clinical trials of peptide vaccines have been conducted. However, these vaccines have provided clinical benefits in only a small fraction of patients. The purpose of the present study was to explore microRNAs (miRNAs) as novel predictive biomarkers for the efficacy of vaccine treatment against colorectal cancer. First, we carried out microarray analysis of pretreatment cancer tissues in a phase I study, in which peptide vaccines alone were given. Candidate miRNAs were selected by comparison of the better prognosis group with the poorer prognosis group. Next, we conducted microarray analysis of cancer tissues in a phase II study, in which peptide vaccines combined with chemotherapy were given. Candidate miRNAs were further selected by a similar comparison of prognosis. Subsequently, we carried out reverse‐transcription PCR analysis of phase II cases, separating cancer tissues into cancer cells and stromal tissue using laser capture microdissection. Treatment effect in relation to overall survival (OS) and miRNA expression was analyzed. Three miRNA predictors were negatively associated with OS: miR‐125b‐1 in cancer cells (P = 0.040), and miR‐378a in both cancer cells (P = 0.009) and stromal cells (P < 0.001). Multivariate analysis showed that expression of miR‐378a in stromal cells was the best among the three predictors (HR, 2.730; 95% CI, 1.027–7.585; P = 0.044). In conclusion, miR‐125b‐1 and miR‐378a expression might be considered as novel biomarkers to predict the efficacy of vaccine treatment against colorectal cancer.

miR-196b, miR-378a and miR-486 are predictive biomarkers for the efficacy of vaccine treatment in colorectal cancer

MicroRNAs (miRNAs/miRs) regulate the levels of transcripts and serve a critical function in the regulation of tumor microenvironments. Therefore, miRNA levels in cancer tissues are thought to be potential biomarkers for immunotherapy. From a phase I trial of a vaccine treatment using 5 human leukocyte antigen (HLA)-A*2402-restricted peptides (registration no. UMIN000004948), colorectal cancer (CRC) tissues were obtained from 8 patients and normal colorectal tissues from 5 patients via surgery. From a phase II trial using the same peptides (registration no. UMIN000001791), CRC tissues were obtained from 16 patients from the HLA-A*2402-matched group and 10 patients from the HLA-A*2402-unmatched group. These tissues were used for miRNA microarray analysis. As the first step, cancer tissues from the phase I study were used and 10 candidate miRNAs were selected by comparing the miRNA expression between two groups; one with improved prognosis and the other with poor prognosis. The miRNAs were subsequently validated using the cases enrolled in the phase II study. Significantly improved prognoses were identified in 16 patients in the HLA-A*2402-matched group with high expression of miR-196b-5p and low expression of miR-378a-3p and miR-486-5p. There was no difference in prognosis in the 10 patients in the HLA-A*2402-unmatched group. Therefore, high miR-196b expression and low miR-378a-3p and miR-486-5p expression were indicated as useful biomarkers for prediction of the efficacy of vaccine treatment for patients with metastatic CRC. In a planned phase III study, expression levels of these 3 miRNAs (miR-196b-5p, miR-378a-3p and miR-486-5p) may be useful biomarkers for assessing patients who are likely to have an improved outcome following vaccination.

Predictive biomarkers for the efficacy of peptide vaccine treatment: based on the results of a phase II study on advanced pancreatic cancer

Background

The purpose of the present study was to explore novel biomarkers that can predict the clinical outcome of patients before treatment or during vaccination. These would be useful for the selection of appropriate patients who would be expected to exhibit better treatment outcomes from vaccination, and for facilitating the development of cancer vaccine treatments.

Methods

From a single-arm, non-randomized, human leukocyte antigen (HLA)-A-status-blind phase II trial of a vaccine treatment using three HLA-A*2402-restricted peptides for advanced pancreatic cancer (PC), we obtained peripheral blood samples from 36 patients of an HLA-A*2402-matched group and 27 patients of an HLA-A*2402-unmatched group.

Results

Multivariate analysis (HR = 2.546; 95% CI = 1.138 to 5.765; p = 0.0231) and log-rank test (p = 0.0036) showed that a high expression level of programmed death-1 (PD-1) on CD4+ T cells was a negative predictive biomarker of overall survival in the HLA-A*2402-matched group . Moreover, a high expression level of PD-1 on CD4+ T cells was a negative predictor for the induction of cytotoxic T lymphocytes (p = 0.0007). After treatment, we found that the upregulation of PD-1 and T cell immunoglobulin mucin-3 (Tim-3) expression on CD4+ and CD8+ T cells was significantly associated with a poor clinical outcome in the HLA-A*2402-matched group (p = 0.0330, 0.0282, 0.0046, and 0.0068, respectively). In contrast, there was no significant difference for these factors in the HLA-A*2402-unmatched group.

Conclusions

Our results indicate that the upregulation of PD-1 and Tim-3 expression on CD4+ and CD8+ T cells may restrict T cell responses in advanced PC patients; therefore, combination immunotherapy with blockade of PD-1 and Tim-3 to restore T cell responses may be a potential therapeutic approach for advanced PC patients.

Trial registration

Clinical-Trail-Registration: UMIN000008082.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0509-1) contains supplementary material, which is available to authorized users.

Phase II clinical trial using novel peptide cocktail vaccine as a postoperative adjuvant treatment for surgically resected pancreatic cancer patients

We investigated peptide cocktail vaccine OCV-C01 containing epitope peptides derived from KIF20A, vascular endothelial growth factor receptor (VEGFR)1 and VEGFR2 combined with gemcitabine in the adjuvant treatment for resected pancreatic cancer patients. A single-arm multicenter phase II study was performed on 30 patients with pancreatic ductal carcinoma who underwent pancreatectomy. At each 28-day treatment cycle, patients received weekly subcutaneous injection of OCV-C01 for 48 weeks and gemcitabine was administered intravenously at 1,000 mg/m2 on days 1, 8 and 15 for 24 weeks. Patients were followed for 18 months. The primary endpoint was disease-free survival (DFS) and secondary endpoints included safety, overall survival (OS) and immunological assays on peptide-specific cytotoxic T lymphocyte (CTL) activity and KIF20A expression in resected pancreatic cancer. The median DFS was 15.8 months [95% confidence interval (CI), 11.1-20.6] and the DFS rate at 18 months was 34.6% (95% CI, 18.3-51.6). The median OS was not reached and the OS rate at 18 months was 69.0% (95% CI, 48.8-82.5). The administration of OCV-C01 was well tolerated. In the per protocol set, there were significant differences in DFS between patients with KIF20A-specific CTL responses and without (p = 0.027), and between patients with KIF20A expression and without (p = 0.014). In addition, all four patients who underwent R0 resection with KIF20A expression had no recurrence of pancreatic cancer with KIF20A-specific CTL responses. OCV-C01 combined with gemcitabine was tolerable with a median DFS of 15.8 months, which was favorable compared with previous data for resected pancreatic cancer.

Phase II clinical trial of peptide cocktail therapy for patients with advanced pancreatic cancer: VENUS-PC study

We previously conducted a phase I clinical trial combining the HLA-A*2402-restricted KIF20A-derived peptide vaccine with gemcitabine for advanced pancreatic cancer (PC) and confirmed its safety and immunogenicity in cancer patients. In this study, we conducted a multicenter, single-armed, phase II trial using two antiangiogenic cancer vaccines targeting VEGFR1 and VEGFR2 in addition to the KIF20A peptide. We attempted to evaluate the clinical benefit of the cancer vaccination in combination with gemcitabine. Chemotherapy naïve PC patients were enrolled to evaluate primarily the 1-year survival rate, and secondarily overall survival (OS), progression free survival (PFS), response rate (RR), disease control rate (DCR) and the peptide-specific immune responses. All enrolled patients received therapy without the HLA-A information, and the HLA genotypes were used for classification of the patients. Between June 2012 and May 2013, a total of 68 patients were enrolled. No severe systemic adverse effects of Grade 3 or higher related to these three peptides were observed. The 1-year survival rates between the HLA-A*2402-matched and -unmatched groups were not significantly different. In the HLA-A*2402 matched group, patients showing peptide-specific CTL induction for KIF20A or VEGFR1 showed a better prognosis compared to those without such induction (P = 0.023, P = 0.009, respectively). In the HLA-A*2402-matched group, the patients who showed a strong injection site reaction had a better survival rate (P = 0.017) compared to those with a weak or no injection site reaction. This phase II study demonstrated that this therapeutic peptide cocktail might be effective in patients who demonstrate peptide-specific immune reactions although predictive biomarkers are needed for patient selection in its further clinical application.

Immunotherapeutic Targeting of Tumor-Associated Blood Vessels

Pathological angiogenesis occurs during tumor progression and leads in the formation of an abnormal vasculature in the tumor microenvironment (TME). The tumor vasculature is disorganized, tortuous and leaky, resulting in high interstitial pressure and hypoxia in the TME, all of which are events that support tumor growth and survival. Given the sustaining role of the tumor vasculature, it has become an increasingly attractive target for the development of anti-cancer therapies. Antibodies, tyrosine kinase inhibitors and cancer vaccines that target pro-angiogenic factors, angiogenesis-associated receptors or tumor blood vessel-associated antigens continue to be developed and tested for therapeutic efficacy. Preferred anti-angiogenic protocols include those that "normalize" the tumor-associated vasculature which reduce hypoxia and improve tumor blood perfusion, resulting in tumor cell apoptosis, decreased immunosuppression, and enhanced effector immune cell infiltration/tumoricidal action within the TME.

MicroRNA-6826 and -6875 in plasma are valuable non‑invasive biomarkers that predict the efficacy of vaccine treatment against metastatic colorectal cancer

Various vaccine treatments against metastatic colorectal cancer have been developed and applied. However, to improve the efficacy of immunotherapy, biomarkers that can predict the effects are needed. It has been reported that various microRNAs (miRNAs) in peripheral blood may be useful as non-invasive biomarkers. In this study, miRNAs influencing the efficacy of vaccine treatment were screened for in a microarray analysis of 13 plasma samples that were obtained from patients prior to vaccine treatment. To validate the screening results, real-time RT-PCR was performed using 93 plasma samples obtained from patients prior to vaccine treatment. Four candidate miRNAs were selected according to the results of the comprehensive analysis of miRNA expression, which were ranked using the Fisher criterion and the absolute value of the log2 ratio in the screening analysis. The validation analysis showed that in the HLA-A*2402-matched patient group (vaccine-treated group), patients with a high expression of plasma miR-6826 had a poorer prognosis than those with a low expression (P=0.048). In contrast, in the HLA-A*2402-unmatched patient group (control group), there was no difference between the patients with high or low plasma miR-6826 expression (P=0.168). Similar results were obtained in the analysis of miR-6875 (P=0.029 and P=0.754, respectively). Moreover, multivariate analysis of the Cox regression model indicated that the expression of miR-6826 was the most significant predictor for overall survival (P=0.003, hazard ratio, 3.670). In conclusion, plasma miR-6826 and miR-6875 may be predictive biomarkers for a poor response to vaccine treatment. Although further clarification is needed regarding the functions of miR-6826 and miR-6875 and their relationship to immune-related molecules, plasma miR-6826 and miR-6875 may be useful negative biomarkers for predicting the efficacy of vaccine treatment.

Cancer anti-angiogenesis vaccines: Is the tumor vasculature antigenically unique?

Angiogenesis is essential for the growth and metastasis of solid tumors. The tumor endothelium exists in a state of chronic activation and proliferation, fueled by the tumor milieu where angiogenic mediators are aberrantly over-expressed. Uncontrolled tumor growth, immune evasion, and therapeutic resistance are all driven by the dysregulated and constitutive angiogenesis occurring in the vasculature. Accordingly, great efforts have been dedicated toward identifying molecular signatures of this pathological angiogenesis in order to devise selective tumor endothelium targeting therapies while minimizing potential autoimmunity against physiologically normal endothelium. Vaccination with angiogenic antigens to generate cellular and/or humoral immunity against the tumor endothelium has proven to be a promising strategy for inhibiting or normalizing tumor angiogenesis and reducing cancer growth. Here we review tumor endothelium vaccines developed to date including active immunization strategies using specific tumor endothelium-associated antigens and whole endothelial cell-based vaccines designed to elicit immune responses against diverse target antigens. Among the novel therapeutic options, we describe a placenta-derived endothelial cell vaccine, ValloVax™, a polyvalent vaccine that is antigenically similar to proliferating tumor endothelium and is supported by pre-clinical studies to be safe and efficacious against several tumor types.

Peptide-Based Treatment: A Promising Cancer Therapy

Many new therapies are currently being used to treat cancer. Among these new methods, chemotherapy based on peptides has been of great interest due to the unique advantages of peptides, such as a low molecular weight, the ability to specifically target tumor cells, and low toxicity in normal tissues. In treating cancer, peptide-based chemotherapy can be mainly divided into three types, peptide-alone therapy, peptide vaccines, and peptide-conjugated nanomaterials. Peptide-alone therapy may specifically enhance the immune system's response to kill tumor cells. Peptide-based vaccines have been used in advanced cancers to improve patients' overall survival. Additionally, the combination of peptides with nanomaterials expands the therapeutic ability of peptides to treat cancer by enhancing drug delivery and sensitivity. In this review, we mainly focus on the new advances in the application of peptides in treating cancer in recent years, including diagnosis, treatment, and prognosis.

Vaccination approach to anti-angiogenic treatment of cancer

Improvement of patient survival by anti-angiogenic therapy has proven limited. A vaccination approach inducing an immune response against the tumor vasculature combines the benefits of immunotherapy and anti-angiogenesis, and may overcome the limitations of current anti-angiogenic drugs. Strategies to use whole endothelial cell vaccines and DNA- or protein vaccines against key players in the VEGF signaling axis, as well as specific markers of tumor endothelial cells, have been tested in preclinical studies. Current clinical trials are now testing the promise of this specific anti-cancer vaccination approach. This review will highlight the state-of-the-art in this exciting field of cancer research.

P53, hTERT, WT-1, and VEGFR2 are the most suitable targets for cancer vaccine therapy in HLA-A24 positive pancreatic adenocarcinoma

Cancer vaccine therapy is one of the most attractive therapies as a new treatment procedure for pancreatic adenocarcinoma. Recent technical advances have enabled the identification of cytotoxic T lymphocyte (CTL) epitopes in various tumor-associated antigens (TAAs). However, little is known about which TAA and its epitope are the most immunogenic and useful for a cancer vaccine for pancreatic adenocarcinoma. We examined the expression of 17 kinds of TAA in 9 pancreatic cancer cell lines and 12 pancreatic cancer tissues. CTL responses to 23 epitopes derived from these TAAs were analyzed using enzyme-linked immunospot (ELISPOT), CTL, and tetramer assays in 41 patients, and factors affecting the immune responses were investigated. All TAAs were frequently expressed in pancreatic adenocarcinoma cells, except for adenocarcinoma antigens recognized by T cells 1, melanoma-associated antigen (MAGE)-A1, and MAGE-A3. Among the epitopes recognized by CTLs in more than two patients in the ELISPOT assay, 6 epitopes derived from 5 TAAs, namely, MAGE-A3, p53, human telomerase reverse transcriptase (hTERT), Wilms tumor (WT)-1, and vascular endothelial growth factor receptor (VEGFR)2, could induce specific CTLs that showed cytotoxicity against pancreatic cancer cell lines. The frequency of lymphocyte subsets correlated well with TAA-specific immune response. Overall survival was significantly longer in patients with TAA-specific CTL responses than in those without. P53, hTERT, WT-1, and VEGFR2 were shown to be attractive targets for immunotherapy in patients with pancreatic adenocarcinoma, and the induction of TAA-specific CTLs may improve the prognosis of these patients.

A phase ΙI study of five peptides combination with oxaliplatin-based chemotherapy as a first-line therapy for advanced colorectal cancer (FXV study)

BACKGROUND

We previously conducted a phase I trial for advanced colorectal cancer (CRC) using five HLA-A*2402-restricted peptides, three derived from oncoantigens and two from vascular endothelial growth factor (VEGF) receptors, and confirmed safety and immunological responses. To evaluate clinical benefits of cancer vaccination treatment, we conducted a phase II trial using the same peptides in combination with oxaliplatin-based chemotherapy as a first-line therapy.

METHODS

The primary objective of the study was the response rates (RR). Progression free survival (PFS), overall survival (OS), and immunological parameters were evaluated as secondary objective. The planned sample size was more than 40 patients for both HLA2402-matched and -unmatched groups. All patients received a cocktail of five peptides (3 mg each) mixed with 1.5 ml of IFA which was subcutaneously administered weekly for the first 12 weeks followed by biweekly administration. Presence or absence of the HLA-A*2402 genotype were used for classification of patients into two groups.

RESULTS

Between February 2009 and November 2012, ninety-six chemotherapy naïve CRC patients were enrolled under the masking of their HLA-A status. Ninety-three patients received mFOLFOX6 and three received XELOX. Bevacizumab was added in five patients. RR was 62.0% and 60.9% in the HLA-A*2402-matched and -unmatched groups, respectively (p=0.910). The median OS was 20.7 months in the HLA-A*2402-matched group and 24.0 months in the unmatched group (log-rank, p=0.489). In subgroup with a neutrophil/lymphocyte ratio (NLR) of <3.0, patients in the HLA-matched group did not survive significantly longer than those in the unmatched group (log-rank, p=0.289) but showed a delayed response.

CONCLUSIONS

Although no significance was observed for planned statistical efficacy endpoints, a delayed response was observed in subgroup with a NLR of <3.0. Biomarkers such as NLR might be useful for selecting patients with a better treatment outcome by the vaccination.

TRIAL REGISTRATION

Trial registration: UMIN000001791.

Phase I clinical study of multiple epitope peptide vaccine combined with chemoradiation therapy in esophageal cancer patients

Background

Chemoradiation therapy (CRT) has been widely used for unresectable esophageal squamous cell carcinoma (ESCC) patients. However, many patients develop local recurrence after CRT. In this study, we hypothesized that the immunotherapy by peptide vaccine may be effective for the eradication of minimal residual cancer cells after CRT. This study was conducted as a phase I clinical trial of multiple-peptide vaccine therapy combined with CRT on patients with unresectable ESCC.

Patients and methods

HLA-A*2402 positive 11 unresectable chemo-naïve ESCC patients were treated by HLA-A*2402-restricted multi-peptide vaccine combined with CRT. The peptide vaccine included the 5 peptides as follows; TTK protein kinase (TTK), up-regulated lung cancer 10 (URLC10), insulin-like growth factor–II mRNA binding protein 3 (KOC1), vascular endothelial growth factor receptor 1 (VEGFR1) and 2 (VEGFR2). CRT consisted of radiotherapy (60 Gy) with concurrent cisplatin (40 mg/m²) and 5-fluorouracil (400 mg/m²). Peptide vaccines mixed with incomplete Freund’s adjuvant were injected subcutaneously once a week on at least 8 occasions combined with CRT.

Results

Vaccination with CRT therapy was well-tolerated, and no severe adverse effects were observed. In the case of grade 3 toxicities, leucopenia, neutropenia, anemia and thrombocutopenia occurred in 54.5%, 27.3%, 27.3% and 9.1% of patients, respectively. Grade 1 local skin reactions in the injection sites of vaccination were observed in 81.8% of patients. The expressions of HLA class I, URLC10, TTK, KOC1, VEGFR1 and VEGFR2 antigens were observed in the tumor tissues of all patients. All patients showed peptide-specific cytotoxic T lymphocytes responses in at least one of the 5 kinds of peptide antigens during the vaccination. Six cases of complete response (CR) and 5 cases of progressive disease (PD) were observed after the 8^th vaccination. The 4 CR patients who continued the peptide vaccination experienced long consistent CR for 2.0, 2.9 4.5 and 4.6 years.

Conclusions

A combination therapy of multi-peptide vaccine with CRT can successfully be performed with satisfactory levels of safety, and application of this combination therapy may be an effective treatment for patients with unresectable ESCC.

Trial registration

ClinicalTrial.gov, number NCT00632333.

A phase I study of combination vaccine treatment of five therapeutic epitope-peptides for metastatic colorectal cancer; safety, immunological response, and clinical outcome

Background

To evaluate the safety of combination vaccine treatment of multiple peptides, phase I clinical trial was conducted for patients with advanced colorectal cancer using five novel HLA-A*2402-restricted peptides, three peptides derived from oncoantigens, ring finger protein 43 (RNF43), 34 kDa-translocase of the outer mitochondrial membrane (TOMM34), and insulin-like growth factor–II mRNA binding protein 3 (KOC1), and the remaining two from angiogenesis factors, vascular endothelial growth factor receptor 1 (VEGFR1) and VEGFR2.

Methods

Eighteen HLA- A*2402-positive colorectal cancer patients who had failed to standard therapy were enrolled in this study. 0.5 mg, 1.0 mg or 3.0 mg each of the peptides was mixed with incomplete Freund’s adjuvant and then subcutaneously injected at five separated sites once a week. We also examined possible effect of a single site injection of “the cocktail of 5 peptides” on the immunological responses. ELISPOT assay was performed before and after vaccinations in the schedule of every 4 weeks.

Results

The vaccine treatment using multiple peptides was well tolerated without any severe treatment-associated systemic adverse events. Dose-dependent induction of peptide-specific cytotoxic T lymphocytes was observed. The single injection of “peptides cocktail” did not diminish the immunological responses. Regarding the clinical outcome, one patient achieved complete response and 6 patients revealed stable disease for 4 to 7 months. The median overall survival time (MST) was 13.5 months. Patients, in which we detected induction of cytotoxic T lymphocytes specific to 3 or more peptides, revealed significantly better prognosis (MST; 27.8 months) than those with poorer immune responses (MST; 3.7 months) (p = 0.032).

Conclusion

Our cancer vaccine treatment using multiple peptides is a promising approach for advanced colorectal cancer with the minimum risk of systemic adverse reactions.

Clinical trial registration

UMIN-CTR number UMIN000004948.

Phase I clinical trial of peptide vaccination with URLC10 and VEGFR1 epitope peptides in patients with advanced gastric cancer

Peptide vaccine treatment has attracted attention in recent years as a new therapy option for chemotherapy-resistant, advanced, unresectable cancer. The safety of peptide vaccination with HLA-A^*2402-restricted URLC10-A24-177 and VEGFR1-A12-9 1084 epitope peptides (fixed 2-mg dose) was investigated in a phase I clinical trial of patients with advanced gastric cancer who were refractory to chemotherapy. We determined the HLA genotype of the subjects after enrollment, results of which were held by the evaluation committee and kept from both patients and investigators until completion of the study. The primary end-point was safety of the peptide vaccination. The secondary end-points were immunological responses and clinical outcome, which were compared between the HLA-A^*2402-positive and HLA-A^*2402-negative groups. The peptides were subcutaneously administered on day 1, 8, 15 and 22 within a 28-day treatment cycle. A total of 14 patients was enrolled in this study; 12 of the 14 patients received 4 or more vaccinations (at least 1 course). No patient had a severe treatment-related adverse event. Findings from evaluation of clinical responses after a single course showed that 4 cases had stable disease and 8 cases had progressive disease. The median overall survival time (MST) for the 12 patients was 3.9 months. The MSTs in the HLA-A^*2402-positive and HLA-A^*2402-negative groups were, 4.2 and 3.6 months (p= 0.9164), respectively. The results of this study showed that vaccination with URLC10 and VEGFR1 peptides was a safe treatment for advanced gastric cancer. This trial was registered with University Hospital Medical Information Network (UMIN, no. 000002409).

Trial Watch: Peptide vaccines in cancer therapy

Throughout the past 3 decades, along with the recognition that the immune system not only influences oncogenesis and tumor progression, but also determines how established neoplastic lesions respond therapy, renovated enthusiasm has gathered around the possibility of using vaccines as anticancer agents. Such an enthusiasm quickly tempered when it became clear that anticancer vaccines would have to be devised as therapeutic, rather than prophylactic, measures, and that malignant cells often fail to elicit (or actively suppress) innate and adaptive immune responses. Nonetheless, accumulating evidence indicates that a variety of anticancer vaccines, including cell-based, DNA-based, and purified component-based preparations, are capable of circumventing the poorly immunogenic and highly immunosuppressive nature of most tumors and elicit (at least under some circumstances) therapeutically relevant immune responses. Great efforts are currently being devoted to the identification of strategies that may provide anticancer vaccines with the capacity of breaking immunological tolerance and eliciting tumor-associated antigen-specific immunity in a majority of patients. In this sense, promising results have been obtained by combining anticancer vaccines with a relatively varied panels of adjuvants, including multiple immunostimulatory cytokines, Toll-like receptor agonists as well as inhibitors of immune checkpoints. One year ago, in the December issue of OncoImmunology, we discussed the biological mechanisms that underlie the antineoplastic effects of peptide-based vaccines and presented an abundant literature demonstrating the prominent clinical potential of such an approach. Here, we review the latest developments in this exciting area of research, focusing on high-profile studies that have been published during the last 13 mo and clinical trials launched in the same period to evaluate purified peptides or full-length proteins as therapeutic anticancer agents.

Multiple therapeutic peptide vaccines consisting of combined novel cancer testis antigens and anti-angiogenic peptides for patients with non-small cell lung cancer

Background

Vaccine treatment using multiple peptides derived from multiple proteins is considered to be a promising option for cancer immune therapy, but scientific evidence supporting the therapeutic efficacy of multiple peptides is limited.

Methods

We conducted phase I trials using a mixture of multiple therapeutic peptide vaccines to evaluate their safety, immunogenicity and clinical response in patients with advanced/recurrent NSCLC. We administered two different combinations of four HLA-A24-restricted peptides. Two were peptides derived from vascular endothelial growth factor receptor 1 (VEGFR1) and 2 (VEGFR2), and the third was a peptide derived from up-regulated lung cancer 10 (URLC10, which is also called lymphocyte antigen 6 complex locus K [LY6K]). The fourth peptide used was derived from TTK protein kinase (TTK) or cell division associated 1 (CDCA1). Vaccines were administered weekly by subcutaneous injection into the axillary region of patients with montanide ISA-51 incomplete Freund’s adjuvant, until the disease was judged to have progressed or patients requested to be withdrawn from the trial. Immunological responses were primarily evaluated using an IFN-gamma ELiSPOT assay.

Results

Vaccinations were well tolerated with no severe treatment-associated adverse events except for the reactions that occurred at the injection sites. Peptide-specific T cell responses against at least one peptide were observed in 13 of the 15 patients enrolled. Although no patient exhibited complete or partial responses, seven patients (47%) had stable disease for at least 2 months. The median overall survival time was 398 days, and the 1- and 2-year survival rates were 58.3% and 32.8%, respectively.

Conclusion

Peptide vaccine therapy using a mixture of four novel peptides was found to be safe, and is expected to induce strong specific T cell responses.

Trial registration

These studies were registered with ClinicalTrials.gov NCT00633724 and NCT00874588.

Phase I trial of OTS11101, an anti-angiogenic vaccine targeting vascular endothelial growth factor receptor 1 in solid tumor

OTS11101 is a novel peptide vaccine that acts as an angiogenesis inhibitor by inducing cytotoxic T lymphocyte (CTL) cells that specifically target vascular endothelial cells expressing vascular endothelial growth factor (VEGF) receptor 1. We conducted a phase I study to evaluate the safety, tolerability, maximum tolerated dose, and pharmacodynamic biomarker status of this vaccine. Nine patients with advanced solid tumors received 1.0, 2.0, or 3.0 mg of OTS11101 subcutaneously, once a week in a 28-day cycle. Three patients experienced grade 1 injection site reactions, which were the most frequent adverse events. Grade 2 proteinuria and hypertension each occurred in one patient. As other toxicities were generally mild, the maximum tolerated dose was not reached. Furthermore, we explored the induction of specific activated CTLs, and biomarkers related to angiogenesis. A pharmacodynamics study revealed that induction of specific CTLs was observed for a dose of 2.0 and 3.0 mg. The serum concentrations of soluble VEGF receptor 1 and 2 after vaccination increased significantly compared with baseline. A microarray was performed to give a comprehensive analysis of gene expression, suggesting that OTS11101 vaccination resulted in T cell activation in a clinical setting. In conclusion, OTS11101 was well tolerated in patients up to 3.0 mg once weekly and our biomarker analysis suggested that this anti-angiogenesis vaccine is biologically active.

Clinical phase I study of elpamotide, a peptide vaccine for vascular endothelial growth factor receptor 2, in patients with advanced solid tumors

Targeting of tumor angiogenesis with vaccines is a potentially valuable approach to cancer treatment. Elpamotide is an immunogenic peptide derived from vascular endothelial growth factor receptor 2, which is expressed at a high level in vascular endothelial cells. We have now carried out a phase I study to evaluate safety, the maximum tolerated dose, and potential pharmacodynamic biomarkers for this vaccine. Ten HLA-A*24:02-positive patients with advanced refractory solid tumors received elpamotide s.c. at dose levels of 0.5, 1.0, or 2.0 mg once a week on a 28-day cycle. Five patients experienced an injection site reaction of grade 1 and 2, which was the most frequent adverse event. In the 1.0 mg cohort, one patient experienced proteinuria of grade 1 and another patient developed both hypertension and proteinuria of grade 1. No adverse events of grade 3 or higher were observed, and the maximum tolerated dose was therefore not achieved. The serum concentration of soluble vascular endothelial growth factor receptor 2 decreased significantly after elpamotide vaccination. Microarray analysis of gene expression in PBMCs indicated that several pathways related to T cell function and angiogenesis were affected by elpamotide vaccination, supporting the notion that this peptide induces an immune response that targets angiogenesis in the clinical setting. In conclusion, elpamotide is well tolerated and our biomarker analysis indicates that this anti-angiogenic vaccine is biologically active. Clinical trial registration no. UMIN000008336.

Phase I/II study of S-1 plus cisplatin combined with peptide vaccines for human vascular endothelial growth factor receptor 1 and 2 in patients with advanced gastric cancer

The aim of this study was to evaluate the safety and efficacy of vaccination with human leukocyte antigen (HLA)-A24-restricted human vascular endothelial growth factor receptor 1 (VEGFR1)-1084 and VEGFR2-169 combined with chemotherapy in patients with advanced gastric cancer. HLA-A 2402-positive patients with advanced or recurrent adenocarcinoma of the stomach were vaccinated with VEGFR1-1084 and VEGFR2-169 combined with S-1 and cisplatin. The study included 22 patients (median age 60.5 years) who received at least one cycle of the combination therapy. No severe adverse effects caused by the vaccine therapy were observed except for an inflammatory reaction at the site of injection in 6 patients. Twelve patients (55%) showed partial response and 10 had stable disease after two cycles of the combination therapy. The disease control rate (partial response and stable disease) was 100% after two cycles. The median time to progression was 9.6 months and median overall survival was 14.2 months. VEGFR1-1084-specific cytotoxic T lymphocyte (CTL) response was induced in 18 (82%) of the 22 patients and VEGFR2-169-specific CTL response was induced in 18 (82%) of the 22 patients. Patients showing CTL response to VEGFR2-169 peptide had significantly better prognosis than those without, as demonstrated by the overall survival (OS) and time to progression (TTP) (OS, p=0.028, TTP, p=0.006). The combination therapy was well tolerated and highly effective in advanced or recurrent gastric cancer. Substantial specific CTL for both peptides was frequently induced even under chemotherapy. Thus, cancer vaccination combined with standard chemotherapy warrants further analysis as a promising strategy for the treatment of advanced cancer.

Identification of HLA-A24-restricted novel T Cell epitope peptides derived from P-cadherin and kinesin family member 20A

We here identified human leukocyte antigen-(HLA-)A^∗2402-restricted epitope peptides from Cadherin 3, type 1, P-cadherin (CDH3) and kinesin family member 20A (KIF20A) that were found to be specifically expressed in cancer cells through genome-wide expression profile analysis. CDH3-10-807 peptide and KIF20A-10-66 peptide successfully induced specific CTL clones, and these selectively responded to COS7 cells expressing both HLA-A^∗2402 and respective protein while did not respond to parental cells or COS7 cells expressing either HLA-A^∗2402 or respective protein. Furthermore, CTL clones responded to cancer cells that endogenously express HLA-A^∗2402 and respective protein, suggesting that CDH3-10-807 peptide and KIF20A-10-66 peptide are naturally presented on HLA-A^∗2402 molecule of human cancer cells. Our results demonstrated that CDH3-10-807 peptide and KIF20A-10-66 peptide are novel HLA-A24-restricted tumor-associated antigens and would be applicable for CTL-inducing cancer therapies.

Vaccines targeting tumor blood vessel antigens promote CD8(+) T cell-dependent tumor eradication or dormancy in HLA-A2 transgenic mice

We have recently shown that effective cytokine gene therapy of solid tumors in HLA-A2 transgenic (HHD) mice lacking murine MHC class I molecule expression results in the generation of HLA-A2-restricted CD8(+) T effector cells selectively recognizing tumor blood vessel-associated pericytes and/or vascular endothelial cells. Using an HHD model in which HLA-A2(neg) tumor (MC38 colon carcinoma or B16 melanoma) cells are not recognized by the CD8(+) T cell repertoire, we now show that vaccines on the basis of tumor-associated blood vessel Ags (TBVA) elicit protective Tc1-dependent immunity capable of mediating tumor regression or extending overall survival. Vaccine efficacy was not observed if (HLA-A2(neg)) wild-type C57BL/6 mice were instead used as recipient animals. In the HHD model, effective vaccination resulted in profound infiltration of tumor lesions by CD8(+) (but not CD4(+)) T cells, in a coordinate reduction of CD31(+) blood vessels in the tumor microenvironment, and in the "spreading" of CD8(+) T cell responses to alternate TBVA that were not intrinsic to the vaccine. Protective Tc1-mediated immunity was durable and directly recognized pericytes and/or vascular endothelial cells flow-sorted from tumor tissue but not from tumor-uninvolved normal kidneys harvested from these same animals. Strikingly, the depletion of CD8(+), but not CD4(+), T cells at late time points after effective therapy frequently resulted in the recurrence of disease at the site of the regressed primary lesion. This suggests that the vaccine-induced anti-TBVA T cell repertoire can mediate the clinically preferred outcomes of either effectively eradicating tumors or policing a state of (occult) tumor dormancy.

RACK1 regulates VEGF/Flt1-mediated cell migration via activation of a PI3K/Akt pathway

Vascular endothelial growth factor (VEGF) is vital to physiological as well as pathological angiogenesis, and regulates a variety of cellular functions, largely by activating its 2 receptors, fms-like tyrosine kinase (Flt1) and kinase domain receptor (KDR). KDR plays a critical role in the proliferation of endothelial cells by controlling VEGF-induced phospholipase Cγ-protein kinase C (PLCγ-PKC) signaling. The function of Flt1, however, remains to be clarified. Recent evidence has indicated that Flt1 regulates the VEGF-triggered migration of endothelial cells and macrophages. Here, we show that RACK1, a ubiquitously expressed scaffolding protein, functions as an important regulator of this process. We found that RACK1 (receptor for activated protein kinase C 1) binds to Flt1 in vitro. When the endogenous expression of RACK1 was attenuated by RNA interference, the VEGF-driven migration was remarkably suppressed whereas the proliferation was unaffected in a stable Flt1-expressing cell line, AG1-G1-Flt1. Further, we demonstrated that the VEGF/Flt-mediated migration of AG1-G1-Flt1 cells occurred mainly via the activation of the PI3 kinase (PI3K)/Akt and Rac1 pathways, and that RACK1 plays a crucial regulatory role in promoting PI3K/Akt-Rac1 activation.

Intratumoral IL-12 gene therapy results in the crosspriming of Tc1 cells reactive against tumor-associated stromal antigens

HLA-A2 transgenic mice bearing established HLA-A2(neg) B16 melanomas were effectively treated by intratumoral (i.t.) injection of syngeneic dendritic cells (DCs) transduced to express high levels of interleukin (IL)-12, resulting in CD8(+) T cell-dependent antitumor protection. In this model, HLA-A2-restricted CD8(+) T cells do not directly recognize tumor cells and therapeutic benefit was associated with the crosspriming of HLA-A2-restricted type-1 CD8(+) T cells reactive against antigens expressed by stromal cells [i.e., pericytes and vascular endothelial cells (VEC)]. IL-12 gene therapy-induced CD8(+) T cells directly recognized HLA-A2(+) pericytes and VEC flow-sorted from B16 tumor lesions based on interferon (IFN)-γ secretion and translocation of the lytic granule-associated molecule CD107 to the T cell surface after coculture with these target cells. In contrast, these CD8(+) T effector cells failed to recognize pericytes/VEC isolated from the kidneys of tumor-bearing HHD mice. The tumor-associated stromal antigen (TASA)-derived peptides studied are evolutionarily conserved and could be recognized by CD8(+) T cells harvested from the blood of HLA-A2(+) normal donors or melanoma patients after in vitro stimulation. These TASA and their derivative peptides may prove useful in vaccine formulations against solid cancers, as well as, in the immune monitoring of HLA-A2(+) cancer patients receiving therapeutic interventions, such as IL-12 gene therapy.

Therapeutic cancer vaccines in combination with conventional therapy

The clinical efficacy of most therapeutic vaccines against cancer has not yet met its promise. Data are emerging that strongly support the notion that combining immunotherapy with conventional therapies, for example, radiation and chemotherapy may improve efficacy. In particular combination with chemotherapy may lead to improved clinical efficacy by clearing suppressor cells, reboot of the immune system, by rendering tumor cells more susceptible to immune mediated killing, or by activation of cells of the immune system. In addition, a range of tumor antigens have been characterized to allow targeting of proteins coupled to intrinsic properties of cancer cells. For example, proteins associated with drug resistance can be targeted, and form ideal target structures for use in combination with chemotherapy for killing of surviving drug resistant cancer cells. Proteins associated with the malignant phenotype can be targeted to specifically target cancer cells, but proteins targeted by immunotherapy may also simultaneously target cancer cells as well as suppressive cells in the tumor stroma.

The coordinated p53 and estrogen receptor cis-regulation at an FLT1 promoter SNP is specific to genotoxic stress and estrogenic compound

Background

Recently, we established that a C>T single nucleotide polymorphism (SNP) in the promoter of the VEGF receptor FLT1 gene generates a ½ site p53 response element (RE-T) that results in p53 responsiveness of the promoter. The transcriptional control required an estrogen receptor (ER) ½ site response element (ERE1) 225 nt upstream to the RE-T.

Methodology/Principal Findings

Here we report the identification of a second ER ½ site (ERE2) located 145 bp downstream of the RE-T and establish that both EREs can impact p53-mediated transactivation of FLT1-T in a manner that is cell type and ER level dependent. Gene reporter assays and ChIP experiments conducted in the breast cancer-derived MCF7 cells revealed that the ERE2 site was sufficient for p53-mediated ERα recruitment and transactivation of the FLT1-T promoter/reporter construct. Surprisingly, unlike the case for other p53 target promoters, p53-mediated transactivation of FLT1-T constructs or expression of the endogenous FLT1 gene, as well as binding of p53 and ER at the promoter constructs, was inducible by doxorubicin but not by 5-fluorouracil. Furthermore, ER activity at FLT1-T was differentially affected by ER ligands, compared to a control TFF1/pS2 ER target promoter. The p53-related transcription factors (TFs) p73 and p63 had no effect on FLT1 transactivation.

Conclusions/Significance

We establish a new dimension to the p53 master regulatory network where p53-mediated transcription from a ½ site RE can be determined by ER binding at one or more cis-acting EREs in manner that is dependent on level of ER protein, the type of ER ligand and the specific p53-inducing agent.

Growth factor receptor expression in anal squamous lesions: modifications associated with oncogenic human papillomavirus and human immunodeficiency virus

High prevalence of squamous anal lesions is linked to oncogenic human papillomavirus (HPV). Human immunodeficiency virus (HIV) promotes anal carcinogenesis. Epidermal growth factor receptor (EGFR), HER2/neu, c-Met, and vascular endothelial growth factor receptor-1 (VEGFR1) (tyrosine kinase growth factor receptors) are implicated in tumor progression, but little is known about their role in anal lesions. We investigated their expression and distribution in normal, dysplastic, and carcinomatous anal epithelium and then tried to analyze the effects on these variables of HPV and the HIV-positive status. Seventy-one HIV-positive and 47 HIV-negative patients were selected. We studied growth factor receptors, p16 and Ki67 expression, by in situ hybridization, fluorescent in situ hybridization (FISH) and chromogen in situ hybridization (CISH), immunocytochemistry, and morphological quantification in 226 lesions, either infected by HPV6 and 11 (31 condylomas acuminata) or infected with oncogenic HPVs (48 invasive cancers, 147 anal intraepithelial neoplasias). No HER2/neu was detected. Strong EGFR immunolabeling was not accompanied by gene amplification. The number and intensity of EGFR- and c-Met-immunoreactive cells increased significantly during lesion progression, highlighting the effects of oncogenic HPVs. EGFR, c-Met, VEGFR1, and p16 were coexpressed in 96% of invasive cancers. HIV-modified c-Met expression in condyloma acuminata (P < .008) and invasive cancers (P < .02). Strong HIV-related immunodeficiency and an absence of antiretroviral therapy increased c-Met and/or EGFR expression. HIV-positive anal cancers showed correlated c-Met and VEGFR1 (P < .003), strong p16 labeling, and an increased Ki67 proliferation. The finding that EGFR, c-Met, and VEGFR1 involved in carcinogenesis are well-represented and coexpressed in anal cancers, especially in HIV-positive population, suggests possible novel targeted treatments for anal diseases.

Vaccination with xenogeneic tumor endothelial proteins isolated in situ inhibits tumor angiogenesis and spontaneous metastasis

Angiogenesis is critical for tumor growth and metastasis. Tumor tissues induce the expression of angiogenesis-associated proteins on endothelial surface that can be targeted for tumor immunotherapy. In our study, the rat tumor endothelial proteins (EP) were isolated in situ via biotinylation of tumor vascular endothelial luminal surface followed by streptavidin affinity chromatography. The isolated tumor EP contained numerous up-regulated angiogenesis-associated endothelial proteins. The administration of these tumor EP as a vaccine to mice reduced the microvessel density in subcutaneous primary LLC tumors, delayed spontaneous LLC tumor metastasis and prolonged post-surgery life span. T lymphocytes from tumor EP-vaccinated mice lysed human umbilical vascular endothelial cells, but not tumor cells in vitro, in a dose-dependent manner. Furthermore, adoptive transfer of antitumor EP antibodies in vivo targeted to tumor endothelium and inhibited spontaneous LLC tumor metastasis. This study provides a successful preclinical exploration of the active immunotherapy for tumor by targeting tumor angiogenesis.