Immunotherapeutic Agents in Non-small-cell Lung Cancer Finally Coming to the Front Lines

Recent advances in neoantigen vaccines for treating non-small cell lung cancer

The breakthrough of programmed cell death protein 1 (PD-1) blockade therapy has changed the clinical treatment of non-small cell lung cancer (NSCLC) in the past few years. The success of PD-1 blockade therapy has been attributed to high tumor mutation burden and high immunogenicity of lung cancer cells. To further improve the efficacy of NSCLC immunotherapy and overcome the resistance of lung cancer cells to immune checkpoint blockade, new approaches that enhance the active immune response, such as neoantigen vaccines and cellular-based therapies, are urgently required. Neoantigens are considered ideal targets for cancer immunotherapy because of their high immunogenicity and specificity. In this mini review, we first discuss the current advances in neoantigen vaccines for treating cancers and then review the results of preclinical studies and early-phase human clinical trials of neoantigen-based therapies for NSCLC. Finally, we focus on the identification of neoantigens in patients with NSCLC and review the candidate mutations reported by recent studies and our investigations. The review concludes that, in addition to immune checkpoint blockade, approaches targeting neoantigens are promising for improving the efficacy of NSCLC immunotherapy.

Recent Advances in Lung Cancer Therapy Based on Nanomaterials: A Review

Lung cancer is one of the commonest cancers with a significant mortality rate for both genders, particularly in men. Lung cancer is recognized as one of the leading causes of death worldwide, which threatens the lives of over 1.6 million people every day. Although cancer is the leading cause of death in industrialized countries, conventional anticancer medications are unlikely to increase patients' life expectancy and quality of life significantly. In recent years, there are significant advances in the development and applications of nanotechnology in cancer treatment. The superiority of nanostructured approaches is that they act more selectively than traditional agents. This progress led to the development of a novel field of cancer treatment known as nanomedicine. Various formulations based on nanocarriers, including lipids, polymers, liposomes, nanoparticles and dendrimers have opened new horizons in lung cancer therapy. The application and expansion of nano-agents lead to an exciting and challenging research era in pharmaceutical science, especially for the delivery of emerging anti-cancer agents. The objective of this review is to discuss the recent advances in three types of nanoparticle formulations for lung cancer treatments modalities, including liposomes, polymeric micelles, and dendrimers for efficient drug delivery. Afterward, we have summarized the promising clinical data on nanomaterials based therapeutic approaches in ongoing clinical studies.

Modified Sijunzi Decoction Inhibits Epithelial-Mesenchymal Transition of Non-Small Cell Lung Cancer by Attenuating AKT/GSK3β Pathway in vitro and in vivo

Modified Sijunzi Decoction (MSJZD) is an empirical prescription of Traditional Chinese Medicine (TCM) and has been corroborated to be effective in multiple human diseases, but its role in non-small cell lung cancer (NSCLC) is enigmatic. Here we mainly analyze the function and mechanism of MSJZD in NSCLC. In this study, we used a method that coupled ultra-performance liquid chromatography to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) to investigate the major constituents in MSJZD with positive and negative ion modes. Additionally, in in vitro experiments, the effects of serum-containing MSJZD on the biological behavior of NSCLC cells induced by TGF-β1 were assessed by cell function experiments. Then, the influences of serum-containing MSJZD on epithelial-mesenchymal transition (EMT)-related markers were examined by immunofluorescence and western blot assays. Also, the AKT/GSK3β pathway and apoptosis-related markers were estimated by western blotting. Tumor xenografts were generated by subcutaneously injecting A549 cells into BALB/c nude mice to determine the effects of MSJZD in vivo. We first analyzed the composition of MSJZD. In positive ion mode, 47 kinds of components were identified. In negative ion mode, 45 kinds of components were identified. We also found that TGF-β1 contributed to inducing cell morphological changes and EMT progression. In vitro, surprisingly, cell proliferation, migration as well as invasion in NSCLC cells induced by TGF-β1, could be weakened by serum-containing MSJZD, and apoptosis was intensified. Moreover, serum-containing MSJZD weakened EMT passage and AKT/GSK3β pathway activation and induced apoptosis-related markers in NSCLC cells triggered by TGF-β1. In vivo, we discovered that MSJZD attenuated the tumor growth, promoted histopathological damage, and induced apoptosis in A549 tumor-bearing mice. Importantly, MSJZD has also restrained the development of EMT, AKT/GSK3β pathway, and TGF-β1 expression levels in nude mice. These findings demonstrated that MSJZD significantly weakened NSCLC progression by modulating EMT and AKT/GSK3β pathway.

High expression of MAGE-C1 gene in colorectal cancer is associated with its poor prognosis

BACKGROUND

The aim of this study was to explore the relationship between melanoma antigen gene C1 (MAGE-C1) expression and the prognosis for colorectal cancer (CRC), and to establish a mathematical model to comprehensively evaluate the prognosis of patients with CRC.

METHODS

MAGE-C1 was selected by bioinformatics for its greater expression differences in CRC patients. Immunohistochemistry (IHC) was used to detect the expression level of MAGE-C1 in tissue samples of 156 patients with CRC. Kaplan-Meier analysis was employed to assess the relationship between MAGE-C1 and the prognosis of patients with CRC. Univariate and multivariate Cox regression models analyzed the factors affecting the prognosis of CRC patients. Also, the clinicopathological characteristics of patients and genes with clinical concern were integrated to establish a model to comprehensively predict the prognosis of patients with CRC.

RESULTS

MAGE-C1 was found to be highly expressed in 28.8% of CRC patients. MAGE-C1 expression was associated with tumor size, number, and metastasis. Survival analysis showed that CRC patients with high expression of MAGE-C1 had a poor prognosis. Regression analysis demonstrated that MAGE-C1 protein status, T stage, differentiation, Kirsten rat sarcoma (KRAS) status, and v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) status were the independent factors influencing the overall survival of patients with CRC. Meanwhile, MAGE-C1 combined with clinicopathological characteristics and hotspot gene mutations could be used to evaluate the prognosis of CRC.

CONCLUSIONS

Our study shows that MAGE-C1 is differentially expressed in patients with CRC and affects the prognosis of patients. The combination of MAGE-C1, clinicopathological characteristics, and genes with clinical concern can be used to assess the prognosis of CRC.

Diagnostic and Prognostic Significance of Keap1 mRNA Expression for Lung Cancer Based on Microarray and Clinical Information from Oncomine Database

We performed a bioinformatics analysis with validation by multiple databases, aiming to evaluate the diagnostic and prognostic value of Kelch-like ECH-associated protein 1 (Keap1) mRNA for lung cancer, and to explore possible mechanisms. Diagnostic performance of Keap1 mRNA was determined by receiver operating characteristic (ROC) curve analysis. Prognostic implication of Keap1 mRNA was estimated by Kaplan-Meier survival analysis. Co-expressed genes with both Keap1 and Nfe2L2 were identified by LinkedOmics. Mechanisms of Keap1-Nfe2L2-co-expressed genes underlying the pathogenesis of lung cancer were explored by function enrichment and pathway analysis. The ROC curve analysis determined a good diagnostic performance of Keap1 mRNA for lung squamous cell carcinoma (LUSC), with an area under the ROC curve (AUC) of 0.833, sensitivity of 72.7%, and specificity of 90.6% (P<0.001). Multivariate Cox regression recognized high Keap1 mRNA to be an independent risk factor of mortality for overall lung cancer [hazard ratio (HR): 11.034, P=0.044], but an independent antagonistic factor for lung adenocarcinoma (LUAD) (HR: 0.404, P<0.001). Validation by UALCAN and GEPIA supported Oncomine findings regarding the diagnostic value of Keap1 mRNA for LUSC, but denied its prognostic value. After screening, we identified 17 co-expressed genes with both Keap1 and Nfe2L2 for LUAD, and 22 for LUSC, mainly enriched in signaling pathway of oxidative stress-induced gene expression via Nrf2. In conclusion, Keap1 mRNA has a good diagnostic performance, but controversial prognostic efficacy for LUSC. The pathogenesis of lung cancer is associated with Keap1-Nfe2L2-co-expressed genes by signaling pathway of oxidative stress-induced gene expression via Nrf2.

Genotype Driven Therapy for Non-Small Cell Lung Cancer: Resistance, Pan Inhibitors and Immunotherapy

Eighty-five percent of patients with lung cancer present with Non-small Cell Lung Cancer (NSCLC). Targeted therapy approaches are promising treatments for lung cancer. However, despite the development of targeted therapies using Tyrosine Kinase Inhibitors (TKI) as well as monoclonal antibodies, the five-year relative survival rate for lung cancer patients is still only 18%, and patients inevitably become resistant to therapy. Mutations in Kirsten Ras Sarcoma viral homolog (KRAS) and epidermal growth factor receptor (EGFR) are the two most common genetic events in lung adenocarcinoma; they account for 25% and 20% of cases, respectively. Anaplastic Lymphoma Kinase (ALK) is a transmembrane receptor tyrosine kinase, and ALK rearrangements are responsible for 3-7% of NSCLC, predominantly of the adenocarcinoma subtype, and occur in a mutually exclusive manner with KRAS and EGFR mutations. Among drug-resistant NSCLC patients, nearly half exhibit the T790M mutation in exon 20 of EGFR. This review focuses on some basic aspects of molecules involved in NSCLC, the development of resistance to treatments in NSCLC, and advances in lung cancer therapy in the past ten years. Some recent developments such as PD-1-PD-L1 checkpoint-based immunotherapy for NSCLC are also covered.

Uncovering the Tumor Antigen Landscape: What to Know about the Discovery Process

According to the latest available data, cancer is the second leading cause of death, highlighting the need for novel cancer therapeutic approaches. In this context, immunotherapy is emerging as a reliable first-line treatment for many cancers, particularly metastatic melanoma. Indeed, cancer immunotherapy has attracted great interest following the recent clinical approval of antibodies targeting immune checkpoint molecules, such as PD-1, PD-L1, and CTLA-4, that release the brakes of the immune system, thus reviving a field otherwise poorly explored. Cancer immunotherapy mainly relies on the generation and stimulation of cytotoxic CD8 T lymphocytes (CTLs) within the tumor microenvironment (TME), priming T cells and establishing efficient and durable anti-tumor immunity. Therefore, there is a clear need to define and identify immunogenic T cell epitopes to use in therapeutic cancer vaccines. Naturally presented antigens in the human leucocyte antigen-1 (HLA-I) complex on the tumor surface are the main protagonists in evocating a specific anti-tumor CD8+ T cell response. However, the methodologies for their identification have been a major bottleneck for their reliable characterization. Consequently, the field of antigen discovery has yet to improve. The current review is intended to define what are today known as tumor antigens, with a main focus on CTL antigenic peptides. We also review the techniques developed and employed to date for antigen discovery, exploring both the direct elution of HLA-I peptides and the in silico prediction of epitopes. Finally, the last part of the review analyses the future challenges and direction of the antigen discovery field.

Chemotherapy agents induce tartrate-resistant acid phosphatase 5a contributing to the symptom distress in lung cancer patients

Tartrate-resistant acid phosphatase 5a (TRACP5a) is mainly secreted by activated macrophages in chronic inflammation. Serum TRACP5a is associated with symptom distress in lung cancer patients during chemotherapy. Therefore, this study aimed to investigate whether chemotherapy drugs modulate TRACP5a as an inducible marker for symptom distress in lung cancer patients during chemotherapy. In clinical analysis, lung cancer participants completely received the six-cycle chemotherapy process (n = 42). Clinical determinations for TRACP5a, C-reactive protein (CRP), interleukin-6 (IL-6), white blood cells, monocytes, and hemoglobin were analyzed at six time points: BL, C1d8, C2d1, C4d1, C4d8, and Ed28. Meanwhile, five questionnaires for fatigue, sleep disturbance, pain, depression, and confusion were finished before drug treatment. For monocyte-to-macrophage differentiation, THP-1 cells were treated with phorbol 12-myristate 13-acetate (PMA). TRACP5a secretion in THP-1 cells was determined at the following days up to 6 days after 1-day incubation of chemotherapy drugs by dot blotting. Clinical analysis revealed that TRACP5a significantly increased at C1d8 and C4d8, but dropped at C2d1 and Ed28. CRP and IL-6 displayed a broad-range variation, resulting in no significant difference among the assessment time points. In contrast, monocytes decreased at C1d8 and C4d8, but rose again at C2d1 and Ed28. In symptom distress, the changes only in fatigue and sleep disturbance were positively associated with the trend in TRACP5a. In PMA-treated THP-1 cells, TRACP5a significantly increased after stimulation with gemcitabine and paclitaxel. Taken together, induction of TRACP5a by chemotherapy drugs might be generated from monocyte-differentiated macrophages, further causing clinical symptom distress in lung cancer patients.

A general strategy to optimize immunogenicity of HLA-B*0702 restricted cryptic peptides from tumor associated antigens: Design of universal neo-antigen like tumor vaccines for HLA-B*0702 positive patients

Tumor Associated Antigens (TAAs) are the privileged targets of almost all the cancer vaccines tested to date. Unfortunately all these vaccines failed to show a clinical efficacy. The main reason for this failure is the immune tolerance to TAAs that are self-proteins expressed by normal and cancer cells. Self-tolerance to TAAs is directed against their dominant rather than against their cryptic epitopes. The best way to overcome self-tolerance to TAAs would therefore be to target their cryptic epitopes. However, because of their low HLA-I affinity, cryptic peptides are non-immunogenic and cannot be used to stimulate an antitumor immune response unless their immunogenicity has been previously enhanced. In this paper we describe a general approach to enhance immunogenicity of almost all the HLA-B*0702 restricted cryptic peptides derived from TAAs. It consists in substituting residues at position 1 or 9 of low HLA-B*0702 affinity cryptic peptides by an Alanine or a Leucine respectively. These substitutions increase affinity of peptides for HLA-B*0702. These optimized cryptic peptides are strongly immunogenic and very importantly CTL they stimulate recognize their native counterparts.

TAAs derived optimized cryptic peptides can be considered as universal antitumor vaccine since they escape self-tolerance, are immunogenic and are not patient specific.

Melanoma antigen A12 regulates cell cycle via tumor suppressor p21 expression

Melanoma-associated antigen family A (MAGE-A) is a family of cancer/testis antigens that are expressed in malignant tumors but not in normal tissues other than the testes. MAGE-A12 is a MAGE-A family gene whose tumorigenic function in cancer cells remains unclear. Searches of the Oncomine and NextBio databases revealed that malignant tumors show up-regulation of MAGE-A12 mRNA relative to corresponding normal tissue. In PPC1 primary prostatic carcinoma cells and in HCT116 colorectal cancer cells (wild type and p53-depleted), MAGE-A12 gene knockdown using siRNA or shRNA diminishes cancer cell proliferation as assessed by cellular ATP levels, cell counting, and clonogenic assays. FACS analyses of annexin V-PI staining and DNA content show that MAGE-A12 knockdown causes G2/M arrest and apoptosis. In tumor xenografts of HCT116 cells, conditional knockdown of MAGE-A12 suppresses tumor growth. The depletion of MAGE-A12 leads to the accumulation of tumor suppressor p21 in PPC1, HCT116, and p53-depleted HCT116 cells. Conversely, CDKN1A knockdown partially rescues the viability of PPC1 cells transfected with siRNA targeting MAGE-A12, while p21 overexpression leads to proliferation arrest in PPC-1 cells. Furthermore, exogenous MAGE-A12 expression promotes the ubiquitination of p21. Our findings reveal that MAGE-A12 plays crucial roles in p21 stability and tumor growth, suggesting that MAGE-A12 could provide a novel target for cancer treatment.

Expression of cancer/testis antigens in salivary gland carcinomas with reference to MAGE-A and NY-ESO-1 expression in adenoid cystic carcinoma

AIMS

Cancer/testis antigens (CTAs) are detected in cancer cells but not in healthy normal tissues, with the exception of gametogenic tissues. CTAs are highly immunogenic proteins, and thus represent ideal targets for cytotoxic T-lymphocyte-mediated specific immune therapy. The aim of this study was to screen CTA expression in various types of salivary gland carcinoma and to clarify clinicopathological significance of MAGE-A and NY-ESO-1 expression in adenoid cystic carcinomas (AdCCs) of the salivary gland, which is one of the most common salivary gland carcinomas, and usually has a fatal outcome.

METHODS AND RESULTS

We used immunohistochemistry to examine the expression of four CTAs (MAGE-A, NY-ESO-1, CT7, and GAGE7) in various types of salivary gland carcinoma (n = 95). When carcinoma cases were divided into low-grade and intermediate/high-grade types, NY-ESO-1 and CT7 were expressed more frequently in intermediate/high-grade carcinomas. We then focused on MAGE-A and NY-ESO-1 expression in a large cohort of adenoid cystic carcinomas (AdCCs) (n = 46). MAGE-A and NY-ESO-1 were frequently expressed in AdCC; specifically, MAGE-A was expressed in >60% of the AdCC cases. MAGE-A expression and tumour site (minor salivary gland) were identified as independent risk factors for locoregional tumour recurrence.

CONCLUSIONS

These findings suggest that CTAs may be expressed in a variety of salivary gland carcinomas, especially in those with higher histological grades. In addition, MAGE-A, which is frequently expressed in AdCC cases, may be a useful prognostic factor for poorer locoregional recurrence-free survival.

Immunotherapy with Dendritic Cells Modified with Tumor-Associated Antigen Gene Demonstrates Enhanced Antitumor Effect Against Lung Cancer

BACKGROUND: Immunotherapy using dendritic cell (DC) vaccine has the potential to overcome the bottleneck of cancer therapy. METHODS: We engineered Lewis lung cancer cells (LLCs) and bone marrow–derived DCs to express tumor-associated antigen (TAA) ovalbumin (OVA) via lentiviral vector plasmid encoding OVA gene. We then tested the antitumor effect of modified DCs both in vitro and in vivo. RESULTS: The results demonstrated that in vitro modified DCs could dramatically enhance T-cell proliferation (P < .01) and killing of LLCs than control groups (P < .05). Moreover, modified DCs could reduce tumor size and prolong the survival of LLC tumor-bearing mice than control groups (P < .01 and P < .01, respectively). Mechanistically, modified DCs demonstrated enhanced homing to T-cell–rich compartments and triggered more naive T cells to become cytotoxic T lymphocytes, which exhibited significant infiltration into the tumors. Interestingly, modified DCs also markedly reduced tumor cells harboring stem cell markers in mice (P < .05), suggesting the potential role on cancer stem-like cells. CONCLUSION: These findings suggested that DCs bioengineered with TAA could enhance antitumor effect and therefore represent a novel anticancer strategy that is worth further exploration.

The efficacy and safety of immunotherapy in patients with advanced NSCLC: a systematic review and meta-analysis

Immunotherapy is a novel treatment for advanced non-small cell lung cancer (NSCLC) patients. Immunotherapy includes two main broad classes of therapeutic vaccines and immune checkpoint inhibitors, as well as cytokines, biological response modifiers and cellular therapy. The present systematic review and meta-analysis aims to evaluate the efficacy and safety of different classes of immunotherapy in patients with advanced NSCLC. Literature search was done on Medline, Embase and Cochrane Library. The primary endpoints were overall survival (OS) and grade ≥3 adverse events. Twenty randomized controlled trials were finally identified in our study. Efficacy analysis indicated an improvement of OS in advanced NSCLC patients after treating by therapeutic vaccines and immune checkpoint inhibitors, but not for other immunomodulators. Safety analysis showed that immunotherapy was well-tolerated. All kinds of grade ≥3 adverse events were similar between experimental group and control group except that neutropenia and thrombocytopenia had a higher incidence in patients received vaccines. In conclusion, immunotherapy is a promising treatment for advanced NSCLC patients. Our findings will be further confirmed and supplemented by several phase II and phase III RCTs which are going to complete in near future.

Novel cancer antigens for personalized immunotherapies: latest evidence and clinical potential

The clinical success of monoclonal antibody immune checkpoint modulators such as ipilimumab, which targets cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and the recently approved agents nivolumab and pembrolizumab, which target programmed cell death receptor 1 (PD-1), has stimulated renewed enthusiasm for anticancer immunotherapy, which was heralded by Science as 'Breakthrough of the Year' in 2013. As the potential of cancer immunotherapy has been recognized since the 1890s when William Coley showed that bacterial products could be beneficial in cancer patients, leveraging the immune system in the treatment of cancer is certainly not a new concept; however, earlier attempts to develop effective therapeutic vaccines and antibodies against solid tumors, for example, melanoma, frequently met with failure due in part to self-tolerance and the development of an immunosuppressive tumor microenvironment. Increased knowledge of the mechanisms through which cancer evades the immune system and the identification of tumor-associated antigens (TAAs) and negative immune checkpoint regulators have led to the development of vaccines and monoclonal antibodies targeting specific tumor antigens and immune checkpoints such as CTLA-4 and PD-1. This review first discusses the established targets of currently approved cancer immunotherapies and then focuses on investigational cancer antigens and their clinical potential. Because of the highly heterogeneous nature of tumors, effective anticancer immunotherapy-based treatment regimens will likely require a personalized combination of therapeutic vaccines, antibodies and chemotherapy that fit the specific biology of a patient's disease.

Current and future targeted therapies for non-small-cell lung cancers with aberrant EGF receptors

Expression of the EGF receptors (EGFRs) is abnormally high in many types of cancer, including 25% of lung cancers. Successful treatments target mutations in the EGFR tyrosine kinase domain with EGFR tyrosine kinase inhibitors (TKIs). However, almost all patients develop resistance to this treatment, and acquired resistance to first-generation TKI has prompted the clinical development of a second generation of EGFR TKI. Because of the development of resistance to treatment of TKIs, there is a need to collect genomic information about EGFR levels in non-small-cell lung cancer patients. Herein, we focus on current molecular targets that have therapies available as well as other targets for which therapies will be available in the near future.

The MAGE protein family and cancer

The Melanoma Antigen Gene (MAGE) protein family is a large, highly conserved group of proteins that share a common MAGE homology domain. Intriguingly, many MAGE proteins are restricted in expression to reproductive tissues, but are aberrantly expressed in a wide variety of cancer types. Originally discovered as antigens on tumor cells and developed as cancer immunotherapy targets, recent literature suggests a more prominent role for MAGEs in driving tumorigenesis. This review will highlight recent developments into the function of MAGEs as oncogenes, their mechanisms of action in regulation of ubiquitin ligases, and outstanding questions in the field.

CIMAvax EGF (EGF-P64K) vaccine for the treatment of non-small-cell lung cancer

Epidermal growth factor receptor (EGFR) is overexpressed in many epithelial tumors and its role in the development of non-small-cell lung cancer (NSCLC) is widely documented. CIMAvax-EGF is a therapeutic cancer vaccine composed by recombinant EGF conjugated to a carrier protein and emulsified in Montanide ISA51. Vaccination induces antibodies against self-EGF that block EGF-EGFR interaction and inhibit EGFR phosphorylation. Five clinical trials were conducted to optimize vaccine formulation and schedule. Then, two randomized studies were completed in advanced NSCLC, where CIMAvax-EGF was administered after chemotherapy, as 'switch maintenance'. The vaccine was very well tolerated and the most frequent adverse events consisted of grade 1/2 injection site reactions, fever, headache, vomiting and chills. CIMAvax was immunogenic and EGF concentration was reduced after vaccination. Subjects receiving a minimum of 4 vaccine doses had a significant survival advantage. NSCLC patients with high EGF concentration at baseline had the largest benefit, comparable with best maintenance therapies.

Approaches to improve development methods for therapeutic cancer vaccines

Therapeutic cancer vaccines are an immunotherapy that amplify or induce an active immune response against tumors. Notably, limitations in the methodology for existing anti-cancer drugs may subsist while applying them to cancer vaccine therapy. A retrospective analysis was performed using information obtained from ClinicalTrials.gov, PubMed, and published articles. Our research evaluated the optimal methodologies for therapeutic cancer vaccines based on (1) patient populations, (2) immune monitoring, (3) tumor response evaluation, and (4) supplementary therapies. Failure to optimize these methodologies at an early phase may impact development at later stages; thus, we have proposed some points to be considered during the early phase. Moreover, we compared our proposal with the guidance for industry issued by the US Food and Drug Administration in October 2011 entitled "Clinical Considerations for Therapeutic Cancer Vaccines". Consequently, while our research was aligned with the guidance, we hope it provides further insights in order to predict the risks and benefits and facilitate decisions for a new technology. We identified the following points for consideration: (1) include in the selection criteria the immunological stage with a prognostic value, which is as important as the tumor stage; (2) select immunological assays such as phenotype analysis of lymphocytes, based on their features and standardize assay methods; (3) utilize optimal response criteria for immunotherapy in therapeutic cancer vaccine trials; and (4) consider supplementary therapies, including immune checkpoint inhibitors, for future therapeutic cancer vaccines.

Using chemo-drugs or irradiation to break immune tolerance and facilitate immunotherapy in solid cancer

The immunity is dual host-protective and tumor-promoting in cancer development and progression. Many immune suppressive cells and cytokines in microenvironment can prevent cytotoxic T lymphocytes (CTL) and natural killer cells (NK) from killing tumor cells. Chemotherapy drugs and irradiation have been reported helpful in breaking immune tolerance and creating microenvironment for adoptive cell therapy. Low-dose cyclophosphamide or gemcitabine therapy can selectively deplete T regulatory cells (Treg). Paclitaxel can alter cytokine network at the tumor site, and 5-fluorouracil shows a pronounced effect on myeloid-derived suppressor cells (MDSC) depletion. Local tumor irradiation and total body irradiation (TBI) can also affect tumor microenvironment and facilitate immunotherapy. In this review, we summarize the particular effects of these agents and methods on immunomodulation, as well as their potential values in immunotherapy. The combination with immunotherapy represents a novel therapeutic strategy.