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

The quest for nanoparticle-powered vaccines in cancer immunotherapy

Despite recent advancements in cancer treatment, this disease still poses a serious threat to public health. Vaccines play an important role in preventing illness by preparing the body's adaptive and innate immune responses to combat diseases. As our understanding of malignancies and their connection to the immune system improves, there has been a growing interest in priming the immune system to fight malignancies more effectively and comprehensively. One promising approach involves utilizing nanoparticle systems for antigen delivery, which has been shown to potentiate immune responses as vaccines and/or adjuvants. In this review, we comprehensively summarized the immunological mechanisms of cancer vaccines while focusing specifically on the recent applications of various types of nanoparticles in the field of cancer immunotherapy. By exploring these recent breakthroughs, we hope to identify significant challenges and obstacles in making nanoparticle-based vaccines and adjuvants feasible for clinical application. This review serves to assess recent breakthroughs in nanoparticle-based cancer vaccinations and shed light on their prospects and potential barriers. By doing so, we aim to inspire future immunotherapies for cancer that harness the potential of nanotechnology to deliver more effective and targeted treatments.

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.

The tumor microenvironment of colorectal cancer metastases: opportunities in cancer immunotherapy

About a fifth of individuals with colorectal cancer (CRC) present with disease metastasis at the time of diagnosis. While the role of the tumor microenvironment (TME) in governing CRC progression is undeniable, the role of the TME in either establishing or suppressing the formation of distant metastases of CRC is less well established. Despite advances in immunotherapy, many individuals with metastatic CRC do not respond to standard-of-care therapy. Therefore, understanding the role of the TME in establishing distant metastases is essential for developing new immunological agents. Here, we summarize our current understanding of the TME of CRC metastases, describe differences between the TME of primary tumors and their distant metastases, and discuss advances in the design and combinations of immunotherapeutic agents.

The dark side of immunotherapy: pancreatic cancer

Since the journal Science deemed cancer immunotherapy as the "breakthrough of the year" in 2014, there has been an explosion of clinical trials involving immunotherapeutic approaches that, in the last decade - thanks also to the renaissance of the immunosurveillance theory (renamed the three Es theory) - have been continuously and successfully developed. In the latest update of the development of the immuno-oncology drug pipeline, published last November by Nature Review Drug Discovery, it was clearly reported that the immunoactive drugs under study almost doubled in just two years. Of the different classes of passive and active immunotherapies, "cell therapy" is the fastest growing. The aim of this review is to discuss the preclinical and clinical studies that have focused on different immuno-oncology approaches applied to pancreatic cancer, which we assign to the "dark side" of immunotherapy, in the sense that it represents one of the solid tumors showing less response to this type of therapeutic strategy.

Clinical Significance of Tumor-Infiltrating T Cells and Programed Death Ligand-1 in Patients with Pancreatic Cancer

The associations of the immunological status of the pancreatic ductal adenocarcinoma (PDA) microenvironment with prognosis were assessed. A high tumor-infiltrating lymphocyte (TIL) density was associated with a better prognosis. Importantly, even with a high density of TILs, the PDA cells with programed cell death-ligand 1 (PD-L1) expression showed a worse prognosis than the patients with negative PD-L1 expression. A significant association between a better prognosis and a tumor microenvironment with a high TIL density/negative PD-L1 expression was observed. Assessments of a combined immunological status in the tumor microenvironment may predict the prognosis of PDA patients following surgical resection.

RNA-loaded dendritic cells: more than a tour de force in cancer therapeutics

A wide array of therapeutic strategies has been implemented against cancers, yet their clinical benefit is limited. The lack of clinical efficacy of the conventional treatment options might be due to the inept immune competency of the patients. Dendritic cells (DCs) have a vital role in initiating and directing immune responses and have been frequently used as delivery vehicles in clinical research. The recent clinical data suggest the potential use of DCs pulsed with nucleic acid, especially with RNA holds a great potential as an immunotherapeutic measure with compare to other cancer therapeutics. This review mainly deals with the DCs and their role in transfection with RNA in cancer immunotherapy.

Amphiphilic polyanhydride-based recombinant MUC4β-nanovaccine activates dendritic cells

Mucin 4 (MUC4) is a high molecular weight glycoprotein that is differentially overexpressed in pancreatic cancer (PC), functionally contributes to disease progression, and correlates with poor survival. Further, due to its aberrant glycosylation and extensive splicing, MUC4 is a potential target for cancer immunotherapy. Our previous studies have demonstrated the utility of amphiphilic polyanhydride nanoparticles as a useful platform for the development of protein-based prophylactic and therapeutic vaccines. In the present study, we encapsulated purified recombinant human MUC4-beta (MUC4β) protein in polyanhydride (20:80 CPTEG:CPH) nanoparticles (MUC4β-nanovaccine) and evaluated its ability to activate dendritic cells and induce adaptive immunity. Immature dendritic cells when pulsed with MUC4β-nanovaccine exhibited significant increase in the surface expressions of MHC I and MHC II and costimulatory molecules (CD80 and CD86), as well as, secretion of pro-inflammatory cytokines (IFN-γ, IL-6, and IL-12) as compared to cells exposed to MUC4β alone or MUC4β mixed with blank nanoparticles (MUC4β+NP). Following immunization, as compared to the other formulations, MUC4β-nanovaccine elicited higher IgG2b to IgG1 ratio of anti-MUC4β-antibodies suggesting a predominantly Th1-like class switching. Thus, our findings demonstrate MUC4β-nanovaccine as a novel platform for PC immunotherapy.

Long-term survival of pancreatic cancer patients treated with multimodal therapy combined with WT1-targeted dendritic cell vaccines

BACKGROUND/AIM

Pancreatic ductal adenocarcinoma (PDA) remains one of the most aggressive tumors with a dismally poor prognosis. Although surgical resection remains the only potentially curative treatment, most PDAs are not surgically resectable at diagnosis. Therefore, multimodal therapy is urgently needed to improve the long-term survival of PDA patients.

METHODS

Six eligible PDA patients underwent multimodal therapy comprising dendritic cells (DCs) pulsed with Wilms' tumor 1 (WT1) peptide (DC/WT1-I) restricted by the human leukocyte antigen (HLA) class I (A*24:02 or A*02:06) allele, chemotherapy, radiation, and/or surgery. Patient laboratory data, DC/WT1-I-specific delayed-type hypersensitivity (DTH) reactions, and WT1-specific immune responses were analyzed to assess the prognostic markers of multimodal therapy.

RESULTS

Compared to 2-treatment type combinations, multimodal therapy involving 3 to 4 treatment types was significantly associated with longer overall survival (p = 0.0177). Moreover, after 7 DC/WT1-I vaccinations, the progression-free survival (PFS) of PDA patients with a neutrophil to lymphocyte ratio (NLR) or C-reactive protein (CRP) level less than the median was superior to that of PDA patients with values above the median (p = 0.0246). PDA patients with an overall survival (OS)>1000 days had significantly more lymphocytes after one DC/WT1-I vaccination course than did those with an OS<1000 days.

CONCLUSION

Multimodal therapy involving the DC/WT1-I vaccination may benefit patients with advanced PDA. However, comparing the limited number of PDA patients in terms of survival is difficult because the patients were at different disease stages and received different treatments. Further studies are needed to evaluate the clinical benefits of this multimodal therapy.

Dendritic cell-based vaccination: powerful resources of immature dendritic cells against pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PAC) has a poor prognosis. One treatment approach, investigated here, is to reinforce antitumor immunity. Dendritic cells (DCs) are essential for the development and regulation of adaptive host immune responses against tumors. A major role for DCs may be as innate tumoricidal effector cells. We explored the efficacy of vaccination with immature (i)DCs, after selecting optimal conditions for generating immunostimulatory iDCs. We used two models, C57BL/6Jrj mice with ectopic tumors induced by the PAC cell line, Panc02, and genetically engineered (KIC) mice developing PAC. Therapeutic iDC-vaccination resulted in a significant reduction in tumor growth in C57BL/6Jrj mice and prolonged survival in KIC mice. Prophylactic iDC-vaccination prevented subcutaneous tumor development. These protective effects were long-lasting in Panc02-induced tumor development, but not in melanoma. iDC-vaccination impacted the immune status of the hosts by greatly increasing the percentage of CD8⁺ T-cells, and natural killer (NK)1.1⁺ cells, that express granzyme B associated with Lamp-1 and IFN-γ. Efficacy of iDC-vaccination was CD8⁺ T-cell-dependent but NK1.1⁺ cell-independent. We demonstrated the ability of DCs to produce peroxynitrites and to kill tumor cells; this killing activity involved peroxynitrites. Altogether, these findings make killer DCs the pivotal actors in the beneficial clinical outcome that accompanies antitumor immune responses. We asked whether efficacy can be improved by combining DC-vaccination with the FOLFIRINOX regimen. Combined treatment significantly increased the lifespan of KIC mice with PAC. Prolonged treatment with FOLFIRINOX clearly augmented this beneficial effect. Combining iDC-vaccination with FOLFIRINOX may therefore represent a promising therapeutic option for patients with PAC.

Current Molecular and Genetic Aspects of Pancreatic Cancer, the Role of Metastasis Associated Proteins (MTA): A Review

Purpose/aim: To focus on current molecular and genetic aspects and MTA proteins, since pancreatic cancer is a lethal malignant with poor prognosis. Early diagnosis is essential step, contributing to potential curative resection.

MATERIALS AND METHODS

A PubMed search of relevant articles published up to August 2016 was performed to identify current information about pancreatic cancer regarding molecular biomarkers, with emphasis on carcinogenesis, novel therapeutic targets, and MTA proteins.

RESULTS

Understanding the mechanisms involved in the process of carcinogenesis at the molecular level and the recognition of various oncogenes has opened new horizons for both diagnosis and targeted therapy. Metastasis associated (MTA) proteins (MTA1, MTA2, MTA3) comprise a well-established family of biomarkers. The oncogene MTA1 and its expression product MTA1 protein are the most important and adequately studied in the current research. It defines the growth, local invasiveness, lymphatic spread, and metastatic capacity of various malignancies such as colorectal or gastric cancer including also pancreatic cancer. This protein is associated with malignant potential and biological behavior. Consequently, it could contribute to cancer detection since the first stages of carcinogenesis, as well as in prediction of its malignant differentiation grade. The pre-operative information of the possibility of lymph node involvement may also affect the attempt and the extent of curative resection and lymphadenectomy.

CONCLUSIONS

Carcinogenesis and implicated oncogenes, either activators or repressors, concentrate much research interest, as well as being useful as biomarkers and for targeted therapy. MTA proteins could become useful diagnostic and prognostic biomarkers in current management of pancreatic cancer.

Clinical impact of chemotherapy to improve tumor microenvironment of pancreatic cancer

A perioperative multimodal strategy including combination chemotherapy and radiotherapy, in addition to surgical resection, has been acknowledged to improve patient prognosis. However chemotherapy has not been actively applied as an immunomodulating modality because of concerns about various immunosuppressive effects. It has recently been shown that certain chemotherapeutic agents could modify tumor microenvironment and host immune responses through several underlying mechanisms such as immunogenic cell death, local T-cell infiltration and also the eradication of immune-suppressing regulatory cells such as regulatory T cells (Tregs) and myeloid-derived suppressor cells. With the better understanding of the cell components in the tumor microenvironment and the effect of chemotherapy to improve tumor microenvironment, it has been gradually clear that the chemotherapeutic agents is two-edged sword to have both immune promoting and suppressing effects. The cellular components of the tumor microenvironment include infiltrating T lymphocytes, dendritic cells, regulatory T cells, tumor associated macrophages, myeloid derived suppressor cells and cancer associated fibroblasts. Based on the better understanding of tumor microenvironment following chemotherapy, the treatment protocol could be modified as personalized medicine and the prognosis of pancreas cancer would be more improved utilizing multimodal chemotherapy. Here we review the recent advances of chemotherapy to improve tumor microenvironment of pancreatic cancer, introducing the unique feature of tumor microenvironment of pancreatic cancer, interaction between anti-cancer reagents and these constituting cells and future prospects.