Prognostic factors related to add-on dendritic cell vaccines on patients with inoperable pancreatic cancer receiving chemotherapy: a multicenter analysis

Current and future immunotherapeutic approaches in pancreatic cancer treatment

Pancreatic cancer is a major cause of cancer-related death, but despondently, the outlook and prognosis for this resistant type of tumor have remained grim for a long time. Currently, it is extremely challenging to prevent or detect it early enough for effective treatment because patients rarely exhibit symptoms and there are no reliable indicators for detection. Most patients have advanced or spreading cancer that is difficult to treat, and treatments like chemotherapy and radiotherapy can only slightly prolong their life by a few months. Immunotherapy has revolutionized the treatment of pancreatic cancer, yet its effectiveness is limited by the tumor's immunosuppressive and hard-to-reach microenvironment. First, this article explains the immunosuppressive microenvironment of pancreatic cancer and highlights a wide range of immunotherapy options, including therapies involving oncolytic viruses, modified T cells (T-cell receptor [TCR]-engineered and chimeric antigen receptor [CAR] T-cell therapy), CAR natural killer cell therapy, cytokine-induced killer cells, immune checkpoint inhibitors, immunomodulators, cancer vaccines, and strategies targeting myeloid cells in the context of contemporary knowledge and future trends. Lastly, it discusses the main challenges ahead of pancreatic cancer immunotherapy.

Dendritic cell vaccination in combination with erlotinib in a patient with inoperable lung adenocarcinoma: a case report

BACKGROUND

Satisfactory treatment for patients with unresectable advanced lung cancer has not yet been established. We report a case of unresectable advanced lung cancer (stage IIIb: T2aN3M0) treated with a total of 15 doses of dendritic cells pulsed with a Wilms' tumor 1 and mucin 1 vaccine in combination with erlotinib, a small molecule epidermal growth factor receptor tyrosine kinase inhibitor, for more than 699 days without recurrence or metastasis.

CASE PRESENTATION

A 63-year-old Korean woman was diagnosed with lung adenocarcinoma by pathology and computed tomography. The adenocarcinoma showed an epidermal growth factor receptor (EGFR) mutation, no anaplastic lymphoma kinase expression, and less than 1% expression of programmed death ligand 1. She received erlotinib alone for approximately 1 month. She then received erlotinib and the dendritic cells pulsed with Wilms' tumor 1 and mucin 1 vaccine. The diameter of the erythema at the vaccinated sites was 30 mm at 48 hours after the first vaccination. Moreover, it was maintained at more than 20 mm during the periods of vaccination. These results suggested the induction of antitumor immunity by the vaccine. Remarkably, the tumor size decreased significantly to 12 mm, a 65.7% reduction, after combined therapy with eight doses of the dendritic cells pulsed with Wilms' tumor 1 and mucin 1 vaccine and erlotinib for 237 days based on fluorodeoxyglucose uptake by positron emission tomography/computed tomography and computed tomography. Interestingly, after 321 days of combination therapy, the clinical findings improved, and no tumor was detected based on computed tomography. Validation of the tumor's disappearance persisted for at least 587 days after treatment initiation, without any indication of recurrence or metastasis.

CONCLUSION

Standard anticancer therapy combined with the dendritic cells pulsed with Wilms' tumor 1 and mucin 1 vaccine may have therapeutic effects for such patients with unresectable lung adenocarcinoma.

Attitudes, expectations, and lived experiences of cancer patients receiving dendritic cell vaccine therapy in Japan

Objective

Immunotherapeutic approaches to cancer, such as dendritic cell vaccine therapy, promise to improve survival rate but may present unique challenges to patients. However, there is no research on the lived experiences of cancer patients receiving dendritic cell vaccine therapy. The aim of this study was to explore the attitudes, expectations, and experiences of cancer patients receiving dendritic cell vaccine therapy in Japan.

Methods

This was an exploratory qualitative study. A descriptive phenomenological approach was used to investigate the experiences of eight advanced-stage cancer patients (median age: 59.5 years). Data were collected between July 2018 and March 2020 using in-depth semi-structured interviews. Data were analyzed according to Colaizzi's seven-step phenomenological strategy, and EQUATOR's Consolidated Criteria for Reporting Qualitative Research (COREQ) guidelines for qualitative studies were followed.

Results

Four themes emerged from the data analysis: strong concerns about chemotherapy, faith in dendritic cell vaccine therapy, motivation to succeed, and physical and mental changes. The first two themes related to pretreatment attitudes and expectations. The latter two themes expressed participants' experiences during and after therapy.

Conclusions

Dendritic cell vaccine therapy patients expressed fears about the effects of standard treatment, and hope and uncertainty regarding immunotherapy treatment decisions and efficacy. The findings suggest that such patients require nursing care that includes prevention and reduction of chemotherapy side effects, careful observation of patients' well-being, management of patients' expectations and uncertainty, formation of patient-health care practitioner partnerships, and team medicine.

Tumor microenvironment in pancreatic ductal adenocarcinoma: Implications in immunotherapy

Pancreatic ductal adenocarcinoma is one of the most aggressive and lethal cancers. Surgical resection is the only curable treatment option, but it is available for only a small fraction of patients at the time of diagnosis. With current therapeutic regimens, the average 5-year survival rate is less than 10% in pancreatic cancer patients. Immunotherapy has emerged as one of the most promising treatment options for multiple solid tumors of advanced stage. However, its clinical efficacy is suboptimal in most clinical trials on pancreatic cancer. Current studies have suggested that the tumor microenvironment is likely the underlying barrier affecting immunotherapy drug efficacy in pancreatic cancer. In this review, we discuss the role of the tumor microenvironment in pancreatic cancer and the latest advances in immunotherapy on pancreatic cancer.

The Trinity: Interplay among Cancer Cells, Fibroblasts, and Immune Cells in Pancreatic Cancer and Implication of CD8+ T Cell-Orientated Therapy

The microenvironment in tumors is complicated and is constituted by different cell types and stromal proteins. Among the cell types, the abundance of cancer cells, fibroblasts, and immune cells is high and these cells work as the “Trinity” in promoting tumorigenesis. Although unidirectional or bidirectional crosstalk between two independent cell types has been well characterized, the multi-directional interplays between cancer cells, fibroblasts, and immune cells in vitro and in vivo are still unclear. We summarize recent studies in addressing the interaction of the “Trinity” members in the tumor microenvironment and propose a functional network for how these members communicate with each other. In addition, we discuss the underlying mechanisms mediating the interplay. Moreover, correlations of the alterations in the distribution and functionality of cancer cells, fibroblasts, and immune cells under different circumstances are reviewed. Finally, we point out the future application of CD8⁺ T cell-oriented therapy in the treatment of pancreatic cancer.

Baseline immunity predicts prognosis of pancreatic cancer patients treated with WT1 and/or MUC1 peptide-loaded dendritic cell vaccination and a standard chemotherapy

The prognosis of patients with advanced pancreatic cancer is poor despite the recent introduction of immune checkpoint inhibitors. Therefore, the development of new therapeutic approaches is urgently required. In the present phase I/II study, we have evaluated the safety, the efficacy and the prognostic factors of Wilms' tumor 1 (WT1) and/or mucin 1 (MUC1) peptide-loaded dendritic cell (DC) vaccination in combination with a chemotherapy employing gemcitabine plus nab-paclitaxel or a combination chemotherapy regimen consisting of oxaliplatin, irinotecan, fluorouracil and leucovorin (FOLFIRINOX) in patients with advanced or relapsed pancreatic ductal adenocarcinoma (PDAC). Forty-eight eligible patients were enrolled and received the vaccinations approximately every 2-4 weeks at least seven times. No severe adverse events related to the vaccinations were observed. Median progression free survival and overall survival were 8.1 months and 15.1 months, respectively. DC vaccinations augmented tumor specific immunity which might be related to clinical outcome. The multivariate analyses demonstrated that WT1 or MUC1-specific interferonɤ enzyme-linked immunospot number prior to DC vaccination was an independent prognostic factor related to overall survival. These results indicate that DC-based immunotherapy combined with a conventional chemotherapy is safe and has clinical benefits for patients in advanced stage of PDAC. The precise evaluation of the baseline antitumor specific immunity is critical to predict clinical outcome.

Inflammation-Immunity-Nutrition Score: A Novel Prognostic Score for Patients with Resectable Colorectal Cancer

Purpose

This study was designed to investigate the prognostic value of the combination of high-sensitivity C-reactive protein, lymphocyte, and albumin in patients with resectable colorectal cancer.

Patients and Methods

Seven-hundred-and-nineteen patients who underwent colorectal cancer resection in Hubei Cancer Hospital were included. Inflammation-Immunity-Nutrition score (0–6) was constructed based on preoperative high-sensitivity C-reactive protein, lymphocyte, and albumin. Time-dependent receiver operating characteristic curve, decision curve, Kaplan-Meier survival curve, Cox regression, and C-index were conducted to detect the prognostic values of inflammation-immunity-nutrition score. The prognostic values of inflammation-immunity-nutrition score in different subgroups by sex, location of tumor, pathologic stage, and KRAS mutation were also explored. The prognostic performance of inflammation-immunity-nutrition score was further compared with that of other traditional prognostic indicators.

Results

The median follow-up time was 40 months. High inflammation-immunity-nutrition score (>2 scores) presented worse survival, with the adjusted hazard ratios (95% confidence intervals) of 3.106 (2.202–4.380) for overall survival and 2.105 (1.604–2.764) for disease-free survival. Besides, the associations of high inflammation-immunity-nutrition score with overall survival were even stronger in cases with wild type KRAS, with the adjusted hazard ratios (95% confidence intervals) of 4.018 (2.355–6.854). Considering the AUCs, C-indices, and hazard ratios estimates, inflammation-immunity-nutrition score presented better prognostic performance than high-sensitivity modified Glasgow prognostic score, high-sensitivity C-reactive protein to albumin ratio, prognostic nutrition index, carcinoembryonic antigen, and carbohydrate antigen 19-9 for overall survival.

Conclusion

Inflammation-immunity-nutrition score might serve as a powerful prognostic score in patients with colorectal cancer for overall survival, particularly in patients with wild type KRAS.

Role of targeted immunotherapy for pancreatic ductal adenocarcinoma (PDAC) treatment: An overview

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid tumors with a high mortality rate and poor survival rate. Depending on the tumor stage, PDAC is either treated by resection surgery, chemotherapies, or radiotherapies. Various chemotherapeutic agents have been used to treat PDAC, alone or in combination. Despite the combinations, chemotherapy exhibits many side-effects leading to an increase in the toxicity profile amongst the PDAC patients. Additionally, these standard chemotherapeutic agents have only a modest impact on patient survival due to their limited efficacy. PDAC was previously considered as an immunologically silent malignancy, but recent findings have demonstrated that effective immune-mediated tumor cell death can be used for its treatment. PDAC is characterized by an immunosuppressive tumor microenvironment accompanied by the major expression of myeloid-derived suppressor cells (MDSC) and M2 tumor-associated macrophages. In contrast, the expression of CD8⁺ T cells is significantly low. Additionally, infiltration of mast cells in PDAC correlates with the poor prognosis. Immunotherapeutic agents target the immunity mediators and empower them to suppress the tumor and effectively treat PDAC. Different targets are studied and exploited to induce an antitumor immune response in PDAC patients. In recent times, site-specific delivery of immunotherapeutics also gained attention among researchers to effectively treat PDAC. In the present review, existing immunotherapies for PDAC treatment along with their limitations are addressed in detail. The review also includes the pathophysiology, traditional strategies and significance of targeted immunotherapies to combat PDAC effectively. Separately, the identification of ideal targets for the targeted therapy of PDAC is also reviewed exhaustively. Additionally, the review also addresses the applications of targeted immunotherapeutics like checkpoint inhibitors, adoptive T-cell therapy etc.

Predictive factors of poor blood collecting flow during leukocyte apheresis for cellular therapy

Leukocyte apheresis is necessary in various cellular therapies. However, maintenance of a stable flow rate during leukocyte apheresis is often difficult, even in patients or donors without major problems. Despite this, predictive methods and evidence regarding the reality of the situation are limited. We conducted a retrospective analysis involving adult patients who required leukocyte apheresis for the treatment of neoplasms using WT1-pulsed dendritic cell vaccine. Monocytes were separated from apheresis products to obtain dendritic cells. All the patients were pre-evaluated based on laboratory and chest X-ray findings and subjected to an identical apheresis procedure. The occurrence of poor blood collecting flow during leukocyte apheresis was monitored, and the frequency, clinical information, and associated risk factors were analyzed. Among 160 cases, poor blood collecting flow was observed in 53 cases (33.1%) in a median time of 54 min (range, 2-127 min) post-initiation of leukocyte apheresis. Owing to difficulty in obtaining higher collecting flow, a longer procedure time was required, and in some cases, the scheduled apheresis cycles could not be completed. Consequently, the number of harvested monocytes was low. Multivariable analysis indicated that female patients have an increased risk of poor inlet flow rate. Furthermore, prolonged QT dispersion (QTD) calculated using Bazett's formula was found to be a risk factor. Although the patients did not present any major problems during leukocyte apheresis, poor blood collecting flow was observed in some cases. Sex and pre-evaluated QTD might be useful predictors for these cases; however, further prospective evaluation is necessary.

Immunological Gene Signature Associated With the Tumor Microenvironment of Pancreatic Cancer After Neoadjuvant Chemotherapy

OBJECTIVES

Neoadjuvant chemotherapy (NAC) has improved overall survival in patients with pancreatic ductal adenocarcinoma (PDAC), but its effects on immune gene signatures are unknown. Here, we examined the immune transcriptome after NAC for PDAC.

METHODS

Resected tumor specimens were obtained from 140 patients with PDAC who received surgery first (n = 93) or NAC (n = 47). Six patients were randomly selected from each group, and RNA was extracted from tumor tissues. We compared 770 immune-related genes among the 2 groups using nCounterPanCancer Immune Profiling (NanoString Technologies, Seattle, Wash). Gene clusters were classified into 14 immune function groups based on gene ontology argolism by nSolver 4.0 software (NanoString Technologies), and corresponding immune cell function scores were compared.

RESULTS

Eleven genes (LY86, SH2D1A, CD247, TIGIT, CR2, CD83, LAMP3, CXCR4, DUSP4, SELL, and IL2RA) were significantly downregulated in the NAC group. Gene expression analysis showed that the functions of regulatory T cells, B cells, and natural killer CD56 dim cells were significantly decreased in the NAC group.

CONCLUSIONS

Neoadjuvant chemotherapy may suppress regulatory T cells and B-cell function in the PDAC microenvironment. The 11 identified genes could be useful for predicting the efficacy of NAC and could be therapeutic targets for PDAC.

Immunotherapy employing dendritic cell vaccination for patients with advanced or relapsed esophageal cancer

The prognosis of patients with advanced esophageal cancer is poor despite the recent introduction of immune checkpoint inhibitors. In the present pilot study, we have evaluated the safety and the feasibility of Wilms' tumor 1 (WT1) peptide-pulsed dendritic cell (DC) vaccination in combination with OK-432 in patients with advanced or relapsed esophageal cancer. Fifteen eligible patients were enrolled. No severe adverse events related to the vaccinations were observed. Objective response rate and disease control rate were 20% and 40%, respectively. Median progression free survival and overall survival was 4.1 months and 7.0 months, respectively. WT1 peptide-pulsed DC vaccinations augmented WT1specific immunity, which might be related to clinical outcome. These results indicate that DC-based immunotherapy combined with a conventional chemotherapy is safe and feasible for patients in advanced stage of esophageal cancer.

Efficacy of dendritic cell-based immunotherapy produced from cord blood in vitro and in a humanized NSG mouse cancer model

AIM

To produce dendritic cells (DCs) from CD34⁺ stem cells from cord blood and explore their prophylactic and curative effect against tumors by vaccinating humanized NSG mice.

MATERIALS & METHODS

Separated CD34⁺ stem cells from cord blood were cultured for 30 days, and the resultant DCs (CD34-DCs) were collected. The basic function of the CD34-DCs and the cytotoxicity of CD34-cytotoxic-T lymphocytes (CTLs) were tested in vitro, and tumor inhibition in a humanized NSG mouse tumor model was observed.

RESULTS

The number of CD34-DCs reached approximately 9 log. These cells performed functions similar to those of DCs derived from monocytes from peripheral blood (PBMC-DCs). The CTLs of the CD34-DCs (CD34-CTLs) presented a better antitumor effect in vitro. The obvious prophylactic and therapeutic antitumor effects of the CD34-DC vaccine were observed in the humanized NSG mouse models.

CONCLUSION

CD34-DCs from cord blood were sufficient in quantity and quality as a vaccine agent against tumors in vitro and in vivo.

Dendritic Cells Pre-Pulsed with Wilms' Tumor 1 in Optimized Culture for Cancer Vaccination

With recent advances in cancer vaccination therapy targeting tumor-associated antigens (TAAs), dendritic cells (DCs) are considered to play a central role as a cell-based drug delivery system in the bioactive immune environment. Ex vivo generation of monocyte-derived DCs has been conventionally applied in adherent manufacturing systems with separate loading of TAAs before clinical use. We developed DCs pre-pulsed with Wilms’ tumor (WT1) peptides in low-adhesion culture maturation (WT1-DCs). Quality tests (viability, phenotype, and functions) of WT1-DCs were performed for process validation, and findings were compared with those for conventional DCs (cDCs). In comparative analyses, WT1-DCs showed an increase in viability and recovery of the DC/monocyte ratio, displaying lower levels of IL-10 (an immune suppressive cytokine) and a similar antigen-presenting ability in an in vitro cytotoxic T lymphocytes (CTLs) assay with cytomegalovirus, despite lower levels of CD80 and PD-L2. A clinical study revealed that WT1-specific CTLs (WT1-CTLs) were detected upon using the WT1-DCs vaccine in patients with cancer. A DC vaccine containing TAAs produced under an optimized manufacturing protocol is a potentially promising cell-based drug delivery system to induce acquired immunity.

Prophylactic dendritic cell vaccination controls pancreatic cancer growth in a mouse model

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related deaths with high recurrence after surgery due to a paucity of effective post-surgical adjuvant treatments. DC vaccines can activate multiple anti-tumor immune responses but have not been explored for post-surgery PDAC recurrence. Intraperitoneal (IP) delivery may allow increased DC vaccine dosage and migration to lymph nodes. Here, we investigated the role of prophylactic DC vaccination controlling PDAC tumor growth with IP delivery as an administration route for DC vaccination.

METHODS

DC vaccines were generated using ex vivo differentiation and maturation of bone marrow-derived precursors. Twenty mice were divided into four groups (n = 5) and treated with DC vaccines, unpulsed mature DCs, Panc02 lysates or no treatment. After tumor induction, mice underwent three magnetic resonance imaging scans to track tumor growth. Apparent diffusion coefficient (ADC), a quantitative magnetic resonance imaging measurement of tumor microstructure, was calculated. Survival was tracked. Tumor tissue was collected after death and stained with hematoxylin and eosin, Masson's trichrome, terminal deoxynucleotidyl transferase dUTP nick end labeling and anti-CD8 stains for histology.

RESULTS

DC-vaccinated mice demonstrated stronger anti-tumor cytotoxicity compared with control groups on lactate dehydrogenase assay. DC vaccine mice also demonstrated decreased tumor volume, prolonged survival and increased ΔADC compared with control groups. On histology, the DC vaccine group had increased apoptosis, increased CD8+ T cells and decreased collagen. ΔADC negatively correlated with % collagen in tumor tissues.

DISCUSSION

Prophylactic DC vaccination may inhibit PDAC tumor growth during recurrence and prolong survival. ΔADC may be a potential imaging biomarker that correlates with tumor histological features.

Dendritic cells in pancreatic cancer immunotherapy: Vaccines and combination immunotherapies

Despite significant advances over the past decades of research, pancreatic cancer (PC) continues to have the worst 5-year survival of any malignancy. Dendritic cells (DCs) are the most potent professional antigen-presenting cells and are involved in the induction and regulation of antitumor immune responses. DC-based immunotherapy has been used in clinical trials for PC. Although safety, efficacy, and immune activation were reported in patients with PC, DC vaccines have not yet fulfilled their promise. Additional strategies for combinatorial approaches aimed to augment and sustain the antitumor specific immune response elicited by DC vaccines are currently being investigated. Here, we will discuss DC vaccination immunotherapies that are currently under preclinical and clinical investigation and potential combination approaches for treating and improving the survival of PC patients.

In Vivo Administration of Recombinant Human Granulocyte Colony-Stimulating Factor Increases the Immune Effectiveness of Dendritic Cell-Based Cancer Vaccination

Significant recent advances in cancer immunotherapeutics include the vaccination of cancer patients with tumor antigen-associated peptide-pulsed dendritic cells (DCs). DC vaccines with homogeneous, mature, and functional activities are required to achieve effective acquired immunity; however, the yield of autologous monocyte-derived DCs varies in each patient. Priming with a low dose of recombinant human granulocyte colony-stimulating factor (rhG-CSF) 16-18 h prior to apheresis resulted in 50% more harvested monocytes, with a significant increase in the ratio of CD11c⁺CD80⁺ DCs/apheresed monocytes. The detection of antigen-specific cytotoxic T lymphocytes after Wilms' tumor 1-pulsed DC vaccination was higher in patients treated with rhG-CSF than those who were not, based on immune monitoring using tetramer analysis. Our study is the first to report that DC vaccines for cancer immunotherapy primed with low-dose rhG-CSF are expected to achieve higher acquired immunogenicity.

Inhibiting PI3 kinase-γ in both myeloid and plasma cells remodels the suppressive tumor microenvironment in desmoplastic tumors

Phosphoinositide-3-kinases (PI3Ks) are part of signal transducing enzymes that mediate key cellular functions in cancer and immunity. PI3K-γ is crucial for cellular activation and migration in response to certain chemokines. PI3K-γ is highly expressed in myeloid cells and promotes their migration and the production of inflammatory mediators. We found that PI3K-γ was also highly expressed in tumor-associated B cells. IPI-549, the only PI3K-γ inhibitor in clinical development, offers a unique approach to enhance the anti-tumor immune response. We encapsulated IPI-549 in targeted polymeric nanoparticles (NP) and tested its activity in both murine pancreatic cancer and melanoma models. IPI-549 NP significantly decreased tumor growth and prolonged host survival in both models. Importantly, IPI-549 NP treatment reduced the suppressive tumor microenvironment by decreasing both suppressive myeloid and plasma cells in the tumor. We concluded that IPI-549 NP delivery could be a promising method for treating pancreatic cancer and other immune-suppressive tumors.

Phase I/II Pilot Study of Wilms' Tumor 1 Peptide-Pulsed Dendritic Cell Vaccination Combined With Conventional Chemotherapy in Patients With Head and Neck Cancer

The prognosis of metastatic or relapsed head and neck squamous cell carcinoma (HNSCC) remains poor despite the introduction of immune checkpoint blockade agents. We aimed to investigate the safety and the feasibility of a vaccination with Wilms' tumor 1 peptide-loaded dendritic cells (DCs) and OK-432 adjuvant combined with conventional chemotherapy. Eleven eligible patients with metastatic or relapsed HNSCC were enrolled. No severe adverse events related to a vaccination were observed. Five patients had durable stable disease and six other patients had disease progression after DC vaccination. Median progression-free survival and overall survival was 6.4 months and 12.1 months, respectively. DC vaccination augmented Wilms' tumor 1-specific immunity which might be related to clinical outcome. These results indicate that DC-based immunotherapy combined with a conventional chemotherapy is safe and feasible for patients in advanced stage of HNSCC.

Prognostic significance of Wilms' tumor 1 expression in patients with pancreatic ductal adenocarcinoma

The only current curative treatment for patients with pancreatic ductal adenocarcinoma (PDA) is surgical resection, and certain patients still succumb to disease shortly after complete surgical resection. Wilms' tumor 1 (WT1) serves an oncogenic role in various types of tumors; therefore, in the present study, WT1 protein expression in patients with PDA was analyzed and the association with overall survival (OS) and disease-free survival (DFS) time in patients with PDA was assessed following surgical resection. A total of 50 consecutive patients with PDA who received surgical resection between January 2005 and December 2015 at the Jikei University Kashiwa Hospital (Kashiwa, Chiba, Japan) were enrolled. WT1 protein expression in PDA tissue was measured using immunohistochemical staining. Furthermore, laboratory parameters were measured within 2 weeks of surgery, and systemic inflammatory response markers were evaluated. WT1 protein expression was detected in the nucleus and cytoplasm of all PDA cells and in tumor vessels. WT1 exhibited weak staining in the nuclei of all PDA cells; however, the cytoplasmic expression of WT1 levels was classified into four groups: Negative (n=0), weak (n=19), moderate (n=23) and strong (n=8). In patients with PDA, it was demonstrated that the OS and DFS times of patients with weak cytoplasmic WT1 expression were significantly prolonged compared with those of patients with moderate-to-strong cytoplasmic WT1 expression, as determined by log-rank test (P=0.0005 and P=0.0001, respectively). Furthermore, an association between the density of WT1-expressing tumor vessels and worse OS/DFS times was detected. Multivariate analysis also indicated a significant association between the overexpression of WT1 in PDA tissue and worse OS/DFS times. To the best of our knowledge, the present study is the first to demonstrate that moderate-to-strong overexpression of WT1 in the cytoplasm of PDA cells is significantly associated with worse OS/DFS times. Therefore, overexpression of WT1 in the cytoplasm of PDA cells may impact the recurrence and prognosis of patients with PDA following surgical resection. The results further support the development of WT1-targeted therapies to prolong survival in all patients with PDA.

Immunological Analysis and Generation of Dendritic Cells From Lavage Fluid Obtained by Cell-Free and Concentrated Ascites Reinfusion Therapy

Cell-free and concentrated ascites reinfusion therapy (CART) is an effective treatment for patients with refractory ascites. Cellular components such as cancer cells and blood cells are removed and discarded. The aim of this study was to investigate the alteration of immune cells in lavage fluid and the generation of dendritic cells (DCs) from lavage fluid obtained by CART. Flow cytometry analysis showed a trend toward immunosuppression and impairment in innate immunity in lavage fluid. Immature DCs with downregulation of CD14 and increased antigen-uptake were generated by culturing monocytes obtained from lavage fluid with GM-CSF and IL4. Following the culture with proinflammatory mediators, mature DCs with upregulation of CD83 and potent ability of T cell activation were induced. There were no significant phenotypical or functional differences between these DCs and DCs derived from peripheral blood, indicating lavage fluid might be employed for an alternative cellular source for the generation of DCs.

Role of immune cells in pancreatic cancer from bench to clinical application: An updated review

BACKGROUND

Pancreatic cancer (PC) remains difficult to treat, despite the recent advances in various anticancer therapies. Immuno-inflammatory response is considered to be a major risk factor for the development of PC in addition to a combination of genetic background and environmental factors. Although patients with PC exhibit evidence of systemic immune dysfunction, the PC microenvironment is replete with immune cells.

METHODS

We searched PubMed for all relevant English language articles published up to March 2016. They included clinical trials, experimental studies, observational studies, and reviews. Trials enrolled at Clinical trial.gov were also searched.

RESULTS

PC induces an immunosuppressive microenvironment, and intratumoral activation of immunity in PC is attenuated by inhibitory signals that limit immune effector function. Multiple types of immune responses can promote an immunosuppressive microenvironment; key regulators of the host tumor immune response are dendritic cells, natural killer cells, macrophages, myeloid derived suppressor cells, and T cells. The function of these immune cells in PC is also influenced by chemotherapeutic agents and the components in tumor microenvironment such as pancreatic stellate cells. Immunotherapy of PC employs monoclonal antibodies/effector cells generated in vitro or vaccination to stimulate antitumor response. Immune therapy in PC has failed to improve overall survival; however, combination therapies comprising immune checkpoint inhibitors and vaccines have been attempted to increase the response.

CONCLUSION

A number of studies have begun to elucidate the roles of immune cell subtypes and their capacity to function or dysfunction in the tumor microenvironment of PC. It will not be long before immune therapy for PC becomes a clinical reality.

Wilms’ tumor 1 (WT1)-targeted cancer vaccines to extend survival for patients with pancreatic cancer

Despite novel chemotherapy treatments, pancreatic ductal adenocarcinoma (PDA) remains a lethal disease. New targeted cancer vaccines may represent a viable option for patients with PDA. The Wilms’ tumor 1 (WT1) antigen is one of the most widely expressed tumor-associated antigens in various types of tumors, including PDA. Recent reports have indicated that WT1-targeted cancer vaccines for patients with PDA mediated a potent antitumor effect when combined with chemotherapy in preclinical and clinical studies. This review summarizes the early-phase clinical trials of WT1-targeted cancer vaccines (peptide vaccines and dendritic cell-based vaccines) for PDA. Moreover, we will discuss future strategies for PDA treatments using WT1-specific cancer vaccines combined with immune checkpoint therapies to maximize the clinical effectiveness of PDA treatments.

Lung adenocarcinoma may be a more susceptive subtype to a dendritic cell-based cancer vaccine than other subtypes of non-small cell lung cancers: a multicenter retrospective analysis

OBJECTIVE

The J-SICT DC Vaccine Study Group provides dendritic cell (DC) vaccines for compassionate use under unified cell production and patient treatment regimens. We previously reported beneficial effects of DC vaccines on the overall survival of 62 patients with advanced non-small cell lung cancer (NSCLC) in a single-center analysis. Here, we extended analysis to 260 patients with NSCLC who were treated at six centers.

METHODS

Of the 337 patients who met the inclusion criteria, we analyzed 260 patients who received ≥5 peptide-pulsed DC vaccinations once every 2 weeks.

RESULTS

The mean survival time (MST) from diagnosis was 33.0 months (95 % confidence interval [CI]: 27.9-39.2), and that from time of first vaccination was 13.8 months (95 % CI 11.4-16.8). An erythema reaction at the injection site that was ≥30 mm in diameter was correlated most strongly with overall survival from the first vaccine (≥30 vs. < 30 mm: MST 20.4 vs. 8.8 months, P < 0.001). We reported a similar finding in our previous analysis of patients with advanced pancreatic cancer. Interestingly, although such findings were common between patients with adenocarcinoma and those with other subtypes, the former group experienced significantly prolonged overall survival and a higher response rate for erythema (56.3 vs. 37.3 %, respectively, P = 0.014).

CONCLUSIONS

This is the first multicenter study that suggests a possible clinical benefit of DC vaccines for patients with advanced NSCLC, especially those with adenocarcinoma. These findings suggest a specific potential responder population for DC vaccines and warrant further investigation in well-controlled prospective randomized trials.

Synergistic anti-pancreatic cancer immunological effects by treatment with reduced expression in immortalized cells/dickkopf-3 protein and peripheral blood mononuclear cells

BACKGROUND AND AIM

Reduced expression in immortalized cells/dickkopf-3 (REIC/DKK3) is a reported tumor suppressor gene and has potential to become an innovative therapy for various cancers. We examined the antitumor immunological effects of human REIC/DKK3 protein against pancreatic cancer.

METHODS

Activation of extracellular signal-regulated kinases 1 and 2, mammalian target of rapamycin, and signal transducer and activator of transcription 3 by REIC/DKK3 protein was assessed in human peripheral blood mononuclear cells using immunoblotting. Pancreatic cancer cell lines (AsPC-1 and MIA Paca-2) were cocultured with peripheral blood mononuclear cells, and the anticancer effects of REIC/DKK3 protein were assessed using the methyl thiazole tetrazolium, cytotoxicity, and enzyme-linked immunospot assays. The antitumor immunological effects of the combined treatment with REIC/DKK3 protein and peripheral blood mononuclear cells were also assessed in a pancreatic cancer model using non-obese diabetic/severe combined immunodeficiency mice.

RESULTS

The REIC/DKK3 protein activated extracellular signal-regulated kinases 1 and 2, mammalian target of rapamycin, and signal transducer and activator of transcription 3 in peripheral blood mononuclear cells. REIC/DKK3 protein inhibited in vitro cancer cell viability and enhanced cytotoxicity when incubated with peripheral blood mononuclear cells. REIC/DKK3 protein induced significant production of interferon gamma from lymphocytes incubated with pancreatic cancer cells, indicating that CD8+ T cells were activated in the peripheral blood mononuclear cells when cocultured with AsPC-1 and MIA Paca-2 in the presence of REIC/DKK3 protein. Combined treatment with REIC/DKK3 protein and peripheral blood mononuclear cells produced in vivo anticancer immunostimulatory effects on pancreatic cancer cells.

CONCLUSIONS

The REIC/DKK3 protein and peripheral blood mononuclear cells synergistically enhanced anticancer immunological effects against pancreatic cancer cells. The observed immunomodulatory effect of combined treatment likely occurs in adenovirus-mediated REIC/DKK3 gene therapy and provides important clues to the therapeutic mechanisms involving immune cells.

Advances in inducing adaptive immunity using cell-based cancer vaccines: Clinical applications in pancreatic cancer

The incidence of pancreatic ductal adenocarcinoma (PDA) is on the rise, and the prognosis is extremely poor because PDA is highly aggressive and notoriously difficult to treat. Although gemcitabine- or 5-fluorouracil-based chemotherapy is typically offered as a standard of care, most patients do not survive longer than 1 year. Therefore, the development of alternative therapeutic approaches for patients with PDA is imperative. As PDA cells express numerous tumor-associated antigens that are suitable vaccine targets, one promising treatment approach is cancer vaccines. During the last few decades, cell-based cancer vaccines have offered encouraging results in preclinical studies. Cell-based cancer vaccines are mainly generated by presenting whole tumor cells or dendritic cells to cells of the immune system. In particular, several clinical trials have explored cell-based cancer vaccines as a promising therapeutic approach for patients with PDA. Moreover, chemotherapy and cancer vaccines can synergize to result in increased efficacies in patients with PDA. In this review, we will discuss both the effect of cell-based cancer vaccines and advances in terms of future strategies of cancer vaccines for the treatment of PDA patients.

Atorvastatin (Lipitor) attenuates the effects of aspirin on pancreatic cancerogenesis and the chemotherapeutic efficacy of gemcitabine on pancreatic cancer by promoting M2 polarized tumor associated macrophages

BACKGROUND

Interactions of inflammatory cells with pancreatic cancer cells play crucial roles in pancreatic cancer, however the dynamic changes of inflammatory cell populations in pancreatic cancerogensis and after chemotherapy have not been well eclucidated. The combinational use of aspirin and atrovastatin (Lipitor) have been widely prescribled for cardio-cerebral vascular diseases mainly by regulation of inflammations, and they have been also reported to have plausible anti-tumor effects, however their potential roles in pancreatic cancerogenesis and chemotherapeutic effects have been seldom investigated. We scanned the dynamic changes of pan-inflammatory cell populations in pancreatic cancerogensis and after chemotherapy and found the potential target cell populations. Then we tested the roles of aspirin and Lipitor to regulate these inflammatory cell populations and their effects on pancreatic cancerogenesis and chemotherapeutic effects.

METHODS

Cancerogen, dimethylbenzanthracene (DMBA), was used to induce pancreatic cancerogenesis and subcatunous implantation of syngenic murine Panc02 pancreatic cancer cells was adopted as well. Gemcitabine was used for chemotherapy. The peripheral blood, pancreatic lesions and tumor samples were harvested and analyzed to search for the potential target cell populations. The roles of aspirin and Lipitor to regulate these cell populations and their potential effects on pancreatic cancerogenesis and chemotherapeutic efficacy were investigated both in vitro and in vivo.

RESULTS

We found progressive accumulations of myeloid-derived suppressor cells (MDSC) and M2-polarzied tumor associated macrophages(M2) in pancreatic lesions accompanied with dynamic reducations of cytotoxic T cells(CTL) and helper T cells(Th) in the progression of pancreatic cancerogenesis. After gemcitabine treatment, the MDSC significantly reduced, however M2 soared up unexpectedly. Aspirin could significantly inhibit the MDSC and M2 to prevent pancreatic cancerogenesis and improve chemotherapeutic effects of gemcitabine, however Lipitor did not significantly affect MDSC, instead it could promote M2 to attenuate the postive effects of aspirin and gemcitabine.

CONCLUSIONS

MDSC and M2 accumulate in progression of pancreatic cancerogenesis and gemcitabine can induce M2. Aspirin could prevent pancreatic cancerogenesis and improve efficacy of gemcitabine partially by inhibiting MDSC and M2, however when used in combination, Lipitor could weaken the efficacy of aspirin and gemcitabine partially by promoting M2.

Dendritic cell-based vaccine for pancreatic cancer in Japan

“Vaccell” is a dendritic cell (DC)-based cancer vaccine which has been established in Japan. The DCs play central roles in deciding the direction of host immune reactions as well as antigen presentation. We have demonstrated that DCs treated with a streptococcal immune adjuvant OK-432, produce interleukin-12, induce Th1-dominant state, and elicit anti-tumor effects, more powerful than those treated with the known DC-maturating factors. We therefore decided to mature DCs by the OK-432 for making an effective DC vaccine, Vaccell. The 255 patients with inoperable pancreatic cancer who received standard chemotherapy combined with DC vaccines, were analyzed retrospectively. Survival time of the patients with positive delayed type hypersensitivity (DTH) skin reaction was significantly prolonged as compared with that of the patients with negative DTH. The findings strongly suggest that there may be “Responders” for the DC vaccine in advanced pancreatic cancer patients. We next conducted a small-scale prospective clinical study. In this trial, we pulsed HLA class II-restricted WT1 peptide (WT1-II) in addition to HLA class I-restricted peptide (WT1-I) into the DCs. Survival of the patients received WT1-I and -II pulsed DC vaccine was significantly extended as compared to that of the patients received DCs pulsed with WT1-I or WT1-II alone. Furthermore, WT1-specific DTH positive patients showed significantly improved the overall survival as well as progression-free survival as compared to the DTH negative patients. The activation of antigen-specific immune responses by DC vaccine in combination with standard chemotherapy may be associated with a good clinical outcome in advanced pancreatic cancer. We are now planning a pivotal study of the Vaccell in appropriate protocols in Japan.

Effective recovery of highly purified CD326(+) tumor cells from lavage fluid of patients treated with a novel cell-free and concentrated ascites reinfusion therapy (KM-CART)

For the production of tumor-specific vaccines, including dendritic cell (DC) vaccines, the tumor cells themselves are an ideal source. Floating tumor cells in the ascites fluid from patients with malignant ascites are a good candidate source, but it is not easy to obtain pure tumor cells from ascites because of various types of cell contamination as well as protein aggregates. We here report an effective method to recover pure tumor cells from malignant ascites. We used lavage fluid from 13 patients with malignant ascites who were treated with modified cell-free and concentrated ascites reinfusion therapy (KM-CART). Cellular components were separated from the lavage fluid by centrifugation, enzymatic digestion and hemolysis. Tumor cells were purified by depleting CD45⁺ leukocytes with antibody-conjugated magnetic beads. The tumor cell lysate was extracted by freeze-and-thaw cycles. The mean obtained total cell number was 7.50 × 10⁷ cells (range 4.40 × 10⁶–2.48 × 10⁸ cells). From this fraction, 6.39 × 10⁶ (range 3.23 × 10⁵–2.53 × 10⁷) CD45⁻ cells were collected, and the tumor cell purity was over 80 % defined as CD45⁻CD326⁺. A sufficient amount of tumor lysate, average  = 2416 μg (range 25–8743 μg), was extracted from CD45⁻CD326⁺ tumor cells. We here established an effective method to produce highly purified tumor cells from KM-CART lavage fluid. The clinical feasibility of this simple preparation method for generating tumor lysate should be examined in clinical studies of DC vaccines.

Dendritic Cell-Based Adjuvant Vaccination Targeting Wilms' Tumor 1 in Patients with Advanced Colorectal Cancer

Despite significant recent advances in the development of immune checkpoint inhibitors, the treatment of advanced colorectal cancer involving metastasis to distant organs remains challenging. We conducted a phase I study to investigate the safety and immunogenicity of Wilms’ tumor (WT1) class I/II peptides-pulsed dendritic cell DC vaccination for patients with advanced colorectal cancer. Standard treatment comprising surgical resection and chemotherapy was followed by one course of seven biweekly administrations of 1–2 × 10⁷ DCs with 1–2 KE of OK-432 (streptococcal preparation) in three patients. Clinical efficacy was confirmed based on WT1 expression using immunohistochemistry on paraffin-embedded tissues and immune monitoring using tetramer analysis and enzyme-linked immunosorbent spot (ELISPOT) assays. WT1 expression with human leukocyte antigen (HLA)-class I molecules was detected in surgical resected tissues. Adverse reactions to DC vaccinations were tolerable under an adjuvant setting. WT1-specific cytotoxic T cells were detected by both modified WT1-peptide/HLA-A*24:02 tetramer analysis and/or interferon-γ-producing cells through the use of ELISPOT assays after the first DC vaccination. Immunity acquired from DC vaccination persisted for two years with prolonged disease-free and overall survival. The present study indicated that DC vaccination targeting WT1 demonstrated the safety and immunogenicity as an adjuvant therapy in patients with resectable advanced colorectal cancer.

New targeted therapies in pancreatic cancer

Patients with pancreatic cancer have a poor prognosis with a median survival of 4-6 mo and a 5-year survival of less than 5%. Despite therapy with gemcitabine, patient survival does not exceed 6 mo, likely due to natural resistance to gemcitabine. Therefore, it is hoped that more favorable results can be obtained by using guided immunotherapy against molecular targets. This review summarizes the new leading targeted therapies in pancreatic cancers, focusing on passive and specific immunotherapies. Passive immunotherapy may have a role for treatment in combination with radiochemotherapy, which otherwise destroys the immune system along with tumor cells. It includes mainly therapies targeting against kinases, including epidermal growth factor receptor, Ras/Raf/mitogen-activated protein kinase cascade, human epidermal growth factor receptor 2, insulin growth factor-1 receptor, phosphoinositide 3-kinase/Akt/mTOR and hepatocyte growth factor receptor. Therapies against DNA repair genes, histone deacetylases, microRNA, and pancreatic tumor tissue stromal elements (stromal extracellular matric and stromal pathways) are also discussed. Specific immunotherapies, such as vaccines (whole cell recombinant, peptide, and dendritic cell vaccines), adoptive cell therapy and immunotherapy targeting tumor stem cells, have the role of activating antitumor immune responses. In the future, treatments will likely include personalized medicine, tailored for numerous molecular therapeutic targets of multiple pathogenetic pathways.

Trials of vaccines for pancreatic ductal adenocarcinoma: Is there any hope of an improved prognosis?

Pancreatic tumors are chemoresistant and malignant, and there are very few therapeutic options for pancreatic cancer, as the disease is normally diagnosed at an advanced stage. Although attempts have been made to develop vaccine therapies for pancreatic cancer for a couple of decades, none of the resultant protocols or regimens have succeeded in improving the clinical outcomes of patients. We herein review vaccines tested within the past few years, including peptide, biological and multiple vaccines, and describe the three sets of criteria used to evaluate the therapeutic activity of vaccines in solid tumors.

Trial watch: Dendritic cell-based anticancer therapy

The use of patient-derived dendritic cells (DCs) as a means to elicit therapeutically relevant immune responses in cancer patients has been extensively investigated throughout the past decade. In this context, DCs are generally expanded, exposed to autologous tumor cell lysates or loaded with specific tumor-associated antigens (TAAs), and then reintroduced into patients, often in combination with one or more immunostimulatory agents. As an alternative, TAAs are targeted to DCs in vivo by means of monoclonal antibodies, carbohydrate moieties or viral vectors specific for DC receptors. All these approaches have been shown to (re)activate tumor-specific immune responses in mice, often mediating robust therapeutic effects. In 2010, the first DC-based preparation (sipuleucel-T, also known as Provenge®) has been approved by the US Food and Drug Administration (FDA) for use in humans. Reflecting the central position occupied by DCs in the regulation of immunological tolerance and adaptive immunity, the interest in harnessing them for the development of novel immunotherapeutic anticancer regimens remains high. Here, we summarize recent advances in the preclinical and clinical development of DC-based anticancer therapeutics.