Current immunotherapeutic strategies in pancreatic cancer

Human Papillomavirus-Directed Therapeutics for Human Papillomavirus-Associated Oropharyngeal Cancer

ABSTRACT

Despite the availability of prophylactic human papillomavirus (HPV) vaccines, there is a growing incidence of HPV-associated head and neck squamous cell carcinomas (HPV-HNSCC) worldwide. The viral etiology of HPV-HNSCC provides an opportunity to develop personalized immune-based therapies, which target the unique viral- or tumor-specific proteins. Novel HPV-targeted immunotherapeutic approaches in clinical development are reviewed. Early results from these trials highlight new opportunities and potential challenges ahead. Immunotherapies for HPV-associated HNSCCs will require a tailored combinatorial approach based on preexisting mechanisms of host immune resistance. As the field continues to identify the relevant HPV types 16 and 18 immunogenic epitopes that are presented by diverse HLA class I alleles, improved HPV-targeted biologics and clinical monitoring tools can be developed and applied to a broader cancer patient population.

Clinical trials of vaccines for immunotherapy in pancreatic cancer

A greater understanding of the molecular events that trigger oncogenesis and events that negatively regulate immune responses has allowed for the development of targeted therapies with specific vaccines to match tumor antigens coupled with immunotherapy specifically directed against that tumor's immunosuppressive microenvironment. In order to be effective, vaccine therapies need to both expand the immune response to tumors and overcome immunosuppressive microenvironments therein. Specifically, targeted therapy must be personalized for each cancer patient. While the idea of personalized targeted therapy may seem like a daunting task, it may not be that difficult as it could involve a relatively simple genetic test to identify gene mutations and additional immunohistochemical staining of tumors with antibodies directed against markers of negative immune regulation. The additional cost to personalize cancer therapy with these diagnostic tests is relatively small in comparison to the cost afforded to our healthcare system when inappropriate targeting therapies are administered to patients whose tumors do not express the targets of either the vaccine or the immune modulator. Despite the large cost, cancer patients whose tumors lack the targets of these therapies often receive no benefit from the therapy. The most illogical approach is to develop a study design and perform clinical trials of potential novel targeting drugs without knowledge or confirmation that the patients' tumors express the targets. Current cancer trials for pancreatic cancer patients are discussed in this article.

Clinical importance of B7-H3 expression in human pancreatic cancer

Background:

B7-H3 is a new member of the B7 ligand family and regulates T-cell responses in various conditions. However, the role of B7-H3 in tumour immunity is largely unknown. The purpose of this study was to evaluate the clinical significance of B7-H3 expression in human pancreatic cancer and the therapeutic potential for cancer immunotherapy.

Methods:

We investigated B7-H3 expression in 59 patients with pancreatic cancer by immunohistochemistry and real-time PCR. Furthermore, we examined the anti-tumour effect of B7-H3-blocking monoclonal antibody in vivo in a murine pancreatic cancer model.

Results:

Tumour-related B7-H3 expression was abundant in most human pancreatic cancer tissues and was significantly higher compared with that in non-cancer tissue or normal pancreas. Moreover, its expression was significantly more intense in cases with lymph node metastasis and advanced pathological stage. B7-H3 blockade promoted CD8⁺ T-cell infiltration into the tumour and induced a substantial anti-tumour effect on murine pancreatic cancer. In addition, the combination of gemcitabine with B7-H3 blockade showed a synergistic anti-tumour effect without overt toxicity.

Conclusion:

Our data show for the first time that B7-H3 may have a critical role in pancreatic cancer and provide the rationale for developing a novel cancer immunotherapy against this fatal disease.

Countering tumor-induced immunosuppression during immunotherapy for pancreatic cancer

BACKGROUND

Vaccines for pancreatic cancer have been challenged by a number of factors, especially the immunosuppressive microenvironment within the tumor that allows for escape from immune surveillance.

OBJECTIVE/METHODS

We sought to identify results that define mechanisms of pancreatic-cancer-associated immunosuppression and strategies that might be useful to overcome them thereby resulting in effective immune responses to cancer vaccines capable of deleting pancreatic cancer cells.

RESULTS/CONCLUSION

Immunosuppressive tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSC), and regulatory T cells (Treg) reside in tumors, and their products along with tumor derived products (such as VEGF, TGFbeta and IL-10), create a microenvironment that counters immune activation and attack. Immunotherapy with cancer vaccines must include strategies to modulate these immunosuppressive cell types and tumor byproducts. Clinical trials are beginning to test these strategies.

Progression of pancreatic adenocarcinoma is significantly impeded with a combination of vaccine and COX-2 inhibition

With a 5-year survival rate of <5%, pancreatic cancer is one of the most rapidly fatal malignancies. Current protocols for the treatment of pancreas cancer are not as effective as we desire. In this study, we show that a novel Mucin-1 (MUC1)-based vaccine in combination with a cyclooxygenase-2 inhibitor (celecoxib), and low-dose chemotherapy (gemcitabine) was effective in preventing the progression of preneoplastic intraepithelial lesions to invasive pancreatic ductal adenocarcinomas. The study was conducted in an appropriate triple transgenic model of spontaneous pancreatic cancer induced by the KRAS(G12D) mutation and that expresses human MUC1 as a self molecule. The combination treatment elicited robust antitumor cellular and humoral immune responses and was associated with increased apoptosis in the tumor. The mechanism for the increased immune response was attributed to the down-regulation of circulating prostaglandin E(2) and indoleamine 2, 3,-dioxygenase enzymatic activity, as well as decreased levels of T regulatory and myeloid suppressor cells within the tumor microenvironment. The preclinical data provide the rationale to design clinical trials with a combination of MUC1-based vaccine, celecoxib, and gemcitabine for the treatment of pancreatic cancer.

Enhanced therapeutic effects for human pancreatic cancer by application K-ras and IGF-IR antisense oligodeoxynucleotides

AIM: To investigate the combined effects of K-ras antisense oligodeoxynucleotide (K-ras ASODN) specific to GTT point mutation at codon 12 and type Iinsulin-like growth factor receptor (IGF-IR) antisense oligodeoxynucleotide (IGF-IR ASODN) on proliferation and apoptosis of human pancreatic cancer Patu8988 cells in vitro and in vivo.

METHODS: K-ras gene point mutation and its style at codon 12 of human pancreatic cancer cell line Patu8988 were detected by using polymerase chain reaction with special sequence primers (PCR-SSP) and sequence analysis. According to the mutation style, K-ras mutation ASODN specific to K-ras point mutation at codon 12 was designed and composed. After K-ras ASODN and IGF-IR ASODN treated on Patu8988 cells respectively or cooperatively, the proliferation and morphological change of Patu8988 cells were analyzed by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony forming assay and transmission electron microscopy; the expression of K-ras and IGF-IR mRNA and protein in the treated cells was measured by reverse-transcript polymerase chain reaction (RT-PCR) and flow cytometry respectively; apoptosis was determined by flow cytometry. The combined antitumor activity of K-ras ASODN and IGF-IR ASODN was evaluated in BALB/c nude mice bearing human pancreatic cancer inoculated with Patu8988 cells.

RESULTS: The results of PCR-SSP and sequence analysis showed that the human pancreatic cancer cell line Patu8988 had point mutation at codon 12, and the mutation style was GGT→GTT. 2-32 μg/mL K-ras ASODN and 2-32 μg/mL IGF-IR ASODN could inhibit Patu8988 cells’ growth, induce apoptosis and decrease the expression of K-ras and IGF-IR mRNA and protein alone. However, there was much more effective inhibition of growth and induction of apoptosis by their combination than by each one alone. In tumor bearing mice, the combination of K-ras ASODN and IGF-IR ASODN showed a significant inhibitory effect on the growth of transplanted pancreatic cancer, resulting in a statistically significant difference compared with each alone.

CONCLUSION: It has been found that K-ras ASODN combined with IGF-IR ASODN could cooperatively inhibit the growth of Patu8988 cells, and induce their apoptosis via reinforcing specific down regulation of K-ras and IGF-IR mRNA and protein expression.