Cytokine-induced NK-like T cells: from bench to bedside

Harnessing cytokine-induced killer cells to accelerate diabetic wound healing: an approach to regulating post-traumatic inflammation

Impaired immunohomeostasis in diabetic wounds prolongs inflammation and cytokine dysfunction, thus, delaying or preventing wound-surface healing. Extensive clinical studies have been conducted on cytokine-induced killer (CIK) cells recently, as they can be easily proliferated using a straightforward, inexpensive protocol. Therefore, the function of CIK cells in regulating inflammatory environments has been drawing attention for clinical management. Throughout the current investigation, we discovered the regenerative capacity of these cells in the challenging environment of wounds that heal poorly due to diabetes. We demonstrated that the intravenous injection of CIK cells can re-establish a proregenerative inflammatory microenvironment, promote vascularization and, ultimately, accelerate skin healing in diabetic mice. The results indicated that CIK cell treatment affects macrophage polarization and restores the function of regenerative cells under hyperglycemic conditions. This novel cellular therapy offers a promising intervention for clinical applications through specific inflammatory regulation functions.

Combination therapy of irreversible electroporation and cytokine-induced killer cells for treating mice bearing panc02 pancreatic-cancer xenografts

The current study aimed to investigate the antitumor effects and potent mechanism of cytokine-induced killer (CIK) cells combined with irreversible electroporation (IRE) via Panc02 cell-bearing mouse model in vivo. CIK cells were isolated from the spleens of Panc02 pancreatic-cancer (PC) subcutaneous-xenograft model and the proportion of different lymphocytes was also determined. The antitumor effect of the combination of IRE and CIK cells in a PC subcutaneous-xenograft model was also investigated. The proportion of cells that were positive for CD3+CD8+ and the proportion of CD3+CD56+ cells were both significantly increased after 21 days of in vitro culture. Combined treatment of IRE and CIK cell significantly inhibited tumor growth and increased the survival rate of Panc02 cell-bearing mice. Furthermore, infiltration of lymphocytes into tumor tissue was significantly increased by this combination therapy compared with the untreated group or monotherapy group. In addition, IRE significantly enhanced the expression of chemokine receptors elicited by CIK cells. In conclusion, IRE combined with CIK cells showed superior antitumor efficacy in a PC xenograft model, which we attributed to the promotion of lymphocytic infiltration, as well as to upregulation of chemokine receptor expression and the regulators of CIK cell proliferation.

5 years of clinical DC-CIK/NK cells immunotherapy for acute myeloid leukemia – a summary

Aim: To assess the efficacy of dendritic cells-cytokine induced killer (DC-CIK) and natural killer (NK) cell-based immunotherapy in treating the low- and intermediate-risk acute myeloid leukemia. Patients & methods: DC-CIK or NK cells were infused once every 3 months for 2–4 cycles to 85 patients. Results & conclusion: The 5-year overall survival (OS) and relapse-free survival (RFS) rates were 90.5 and 65.2%, respectively. The OS of the very favorable, the favorable and the intermediate-risk groups was 94.4, 86.3 and 93.3% (p = 0.88), and the RFS 83.3, 81.8 and 62.2% (p = 0.14), respectively. The OS and RFS of the 60 patients treated with DC-CIK alternating with NK cells were better than the 25 patients treated with DC-CIK or NK alone (96.5 vs 71.2%; p = 0.003. 79.5 vs 28.9%; p < 0.001).

Cytokine-Induced Killer Cells Express CD39, CD38, CD203a, CD73 Ectoenzymes and P1 Adenosinergic Receptors

Cytokine-induced killer (CIK) cells, a heterogeneous T cell population obtained by in vitro differentiation of peripheral blood mononuclear cells (PBMC), represent a promising immunological approach in cancer. Numerous studies have explored the role of CD38, CD39, CD203a/PC-1, and CD73 in generating extracellular adenosine (ADO) and thus in shaping the tumor niche in favor of proliferation. The findings shown here reveal that CIK cells are able to produce extracellular ADO via traditional (CD39/CD73) and/or alternative (CD38/CD203a/CD73 or CD203a/CD73) pathways. Transcriptome analysis showed the mRNA expression of these molecules and their modulation during PBMC to CIK differentiation. When PBMC from normal subjects or cancer bearing patients were differentiated into CIK cells under normoxic conditions, CD38 and CD39 were greatly up-regulated while the number of CD203a, and CD73 positive cells underwent minor changes. Since hypoxic conditions are often found in tumors, we asked whether CD39, CD38, CD203a, and CD73 expressed by CIK cells were modulated by hypoxia. PBMC isolated from cancer patients and differentiated into CIK cells in hypoxic conditions did not show relevant changes in CD38, CD39, CD73, CD203a, and CD26. CIK cells also expressed A₁, A_2A, and A_2B ADO receptors and they only underwent minor changes as a consequence of hypoxia. The present study sheds light on a previously unknown functional aspect of CIK cells, opening the possibility of pharmacologically modulated ADO-generating ectoezymes to improve CIK cells performance.

Cytokine-induced killer cells: A novel treatment for allergic airway inflammation

The effectiveness of cytokine-induced killer (CIK) cells for treatment of cancers has long been appreciated. Here, we report for the first time that CIK cells can be applied to treat allergic airway inflammation. Adopting from an established protocol with some modifications, we generated CIK cells ex vivo from mouse T cells, and examined their effectiveness in treatment of allergic airway inflammation using the ovalbumin-induced model of allergic airway inflammation. Based upon evaluation of bronchoalveolar lavage cellularity, T helper type2 cytokine levels and lung histology, all of which are important parameters for determining the severity of allergic airway inflammation, diseased mice treated with CIK cells showed significant reductions in all the parameters without any obvious adverse effects. Interestingly, the observed effects were comparable to those treated with dexamethasone. Thus, our study provides a novel application of CIK cells in treatment of allergic airway inflammation.

Pseudomonas aeruginosa-mannose sensitive hemagglutinin injection treated cytokine-induced killer cells combined with chemotherapy in the treatment of malignancies

Pseudomonas aeruginosa-mannose sensitive hemagglutinin (PA-MSHA) injection serves as immunological adjuvant in clinical treatment of cancer patients. In present study, we investigated whether PA-MSHA injection enhanced the anti-tumor efficacy of CIK cells. Twenty patients with malignancies were enrolled in this retrospective clinical trial. They were divided into two groups: 10 patients received PA-MSHA treated CIK cells transfusion combined with chemotherapy, and other patients accepted CIK cells and chemotherapy. The efficacy of PA-MSHA treated CIK cells was also observed in vitro and in vivo. With PA-MSHA treatment CIK cells exhibited enhanced proliferation but decreased expression of inhibitory cell surface markers such as Tim-3 and PD-1. Particularly in CIK cells, PA-MSHA promoted the extrusion of pro-inflammatory cytokines like IFN-γ. Of 10 patients with PA-MSHA treated CIK cells and chemotherapy, two patients reached partial remissions, 7 patients had stable disease and the other one had progressive disease. Some of these patients experienced fever after cell infusion. 8 patients with CIK cells showed stable disease and 2 patients had progressive disease. Moreover, the side effects were small in patients with CIK treatment. Our data indicated that PA-MSHA improves the functions of CIK cells and shed new light on developing more potent therapeutic approaches for malignancies.

Analytic and Dynamic Secretory Profile of Patient-Derived Cytokine-Induced Killer Cells

Adoptive immunotherapy with Cytokine Induced Killer (CIK) cells has shown antitumor activity against several kinds of cancers in preclinical models and clinical trials. CIK cells are a subset of ex vivo expanded T lymphocytes with T-NK phenotype and MHC-unrestricted antitumor activity. Literature provides scanty information on cytokines, chemokines and growth factors secreted by CIK cells. Therefore, we investigated the secretory profile of CIK cells generated from tumor patients. The secretome analysis was performed at specific time points (day 1, day 14 and day 21) of CIK cells expansion. Mature CIK cells (day 21) produce a great variety of interleukins and secreted proteins that can be divided into 3 groups based on their secretion quantity: high (IL-13, RANTES, MIP-1α and 1β), medium (IL-1Ra, IL-5, IL-8, IL-10, IL-17, IP-10, INF-γ, VEGF and GMCSF) and low (IL-1β, IL-4, IL-6, IL-7, IL-9, IL-12, IL-15, Eotaxin, PDGF-bb, FGF basic, G-CSF and MCP-1) secreted. Moreover, comparing PBMC (day 1) and mature CIK cells (day 14 and 21) secretome, we observed that IL-5, IL-10, IL-13, GM-CSF, VEGF resulted greatly up-regulated, while IL-1β, IL-6, IL-8, IL-15, IL-17, eotaxin, MCP-1, and RANTES were down-regulated. We also performed a gene expression profile analysis of patient-derived CIK cells showing that mRNA for the different cytokines and secreted proteins were modulated during PBMC to CIK differentiation. We highlighted previously unknown secretory properties and provided for the first time a comprehensive molecular characterization of CIK cells. Our findings provide rationale to explore the functional implications and possible therapeutic modulation of CIK secretome.

A brief review of clinical trials involving manipulation of invariant NKT cells as a promising approach in future cancer therapies

In the recent years researchers have put a lot of emphasis on the possible immunotherapeutic strategies able to target tumors. Many studies have proven that the key role in recognition and eradication of cancer cells, both for mice and humans, is being conducted by the invariant natural killer T-cells (NKT). This small subpopulation of lymphocytes can kill other cells, either directly or indirectly, through the natural killer cells’ (NK) activation. They can also swiftly release cytokines, causing the involvement of elements of the innate and acquired immune system. With the discovery of α-galactosylceramide (α-GalCer) – the first known agonist for iNKT cells – and its later subsequent analogs, it became possible to effectively stimulate iNKT cells, hence to keep control over the tumor progression. This article refers to the current knowledge concerning iNKT cells and the most important aspects of their antitumor activity. It also highlights the clinical trials that aim at increasing the amount of iNKT cells in general and in the microenvironment of the tumor. For sure, the iNKT-based immunotherapeutic approach holds a great potential and is highly probable to become a part of the cancer immunotherapy in the future.

Cytotoxic potential of IL-15-activated cytokine-induced killer cells against human neuroblastoma cells

BACKGROUND

Neuroblastoma (NB) is the most common solid extracranial tumor in childhood. Despite advances in therapy, the prognosis is poor and optimized therapies are urgently needed. Therefore, we investigated the antitumor potential of interleukin-15 (IL-15)-activated cytokine-induced killer (CIK) cells against different NB cell lines.

PROCEDURE

CIK cells were generated from peripheral blood mononuclear cells by the stimulation with interferon-γ (IFN-γ), IL-2, OKT-3 and IL-15 over a period of 10-12 days. The cytotoxic activity against NB cells was analyzed by nonradioactive Europium release assay before and after blocking of different receptor-ligand interactions relevant in CIK cell-mediated cytotoxicity.

RESULTS

The final CIK cell products consisted in median of 83% (range: 75.9-91.9%) CD3⁺ CD56^- T cells, 14% (range: 5.2-20.7%) CD3⁺ CD56⁺ NK-like T cells and 2% (range: 0.9-4.8%) CD3^- CD56⁺ NK cells. CIK cells expanded significantly upon ex vivo stimulation with median rates of 22.3-fold for T cells, 58.3-fold for NK-like T cells and 2.5-fold for NK cells. Interestingly, CD25 surface expression increased from less than equal to 1% up to median 79.7%. Cytotoxic activity of CIK cells against NB cells was in median 34.7, 25.9 and 34.8% against the cell lines UKF-NB-3, UKF-NB-4 and SK-N-SH, respectively. In comparison with IL-2-stimulated NK cells, CIK cells showed a significantly higher cytotoxicity. Antibody-mediated blocking of the receptors NKG2D, TRAIL, FasL, DNAM-1, NKp30 and lymphocyte function-associated antigen-1 (LFA-1) significantly reduced lytic activity, indicating that diverse cytotoxic mechanisms might be involved in CIK cell-mediated NB killing.

CONCLUSIONS

Unlike the mechanism reported in other malignancies, NKG2D-mediated cytotoxicity does not constitute the major killing mechanism of CIK cells against NB.

Donor Cell Composition and Reactivity Predict Risk of Acute Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

Background. Graft-versus-host disease (GVHD) is a serious complication after allogeneic hematopoietic stem cell transplantation (HSCT). We designed a functional assay for assessment of individual risk for acute GVHD. Study Design and Methods. Blood samples were collected from patients and donors before HSCT. Two groups of seven patients each were selected, one in which individuals developed acute GVHD grades II-IV and one in which none showed any clinical signs of GVHD. Peripheral blood mononuclear cells (PBMCs) isolated from donors were incubated in mixed lymphocyte cultures (MLCs) with recipient PBMCs. The cells were characterized by flow cytometry before and after MLC. Results. Samples from donors in the GVHD group contained significantly lower frequencies of naïve γδ T-cells and T-cells expressing NK-cell markers CD56 and CD94. Donor samples in this group also exhibited lower frequencies of naïve CD95⁺ T-cells compared to controls. After MLC, there were dissimilarities in the CD4/CD8 T-cell ratio and frequency of CD69⁺ T-cells between the two patient groups, with the non-GVHD group showing higher frequencies of CD8⁺ and CD69⁺ T-cells. Conclusion. We conclude that a thorough flow cytometric analysis of donor cells for phenotype and allogeneic reactivity may be of value when assessing pretransplant risk for severe acute GVHD.

Curative Effects of Dendritic Cells Combined with Cytokine-Induced Killer Cells in Patients with Malignant Pericardial Effusion

Background

To determine the effects of dendritic cells (DCs) and cytokine-induced killer (CIK) cells in patients with malignant pericardial effusion.

Material/Methods

All patients underwent pericardial puncture and indwelling catheter insertion. After pericardial drainage, the 16 patients in the treatment group received an infusion of 20 mL DCs and CIK cells (>1.0×10¹⁰ cells) and 500,000 U interleukin (IL)-2 for 3 successive days. The 15 control-group patients received 30 mg/m² cisplatin and 500,000 U IL-2 for 3 successive days. The treatment effects were assessed using imaging data.

Results

The total efficiency and complete remission rates were higher in the treatment group than in the control group at 4 weeks (total efficiency: 87.50% vs. 73.33%; complete remission: 62.50% vs. 46.67%) and 3 months after the treatment (total efficiency: 81.25% vs. 66.67%; complete remission: 50.00% vs. 40.00%; P<0.05 for all). In both groups, the Karnofsky scores for quality of life improved after treatment. However, the curative effects were better in the treatment group than in the control group (P<0.05). The following adverse reactions occurred: fever, 6 treatment-group patients and 3 control-group patients; chest pain, 2 treatment-group patients and 7 control-group patients; gastrointestinal reactions, 1 treatment-group patient and 6 control-group patients; and bone marrow suppression, 1 treatment-group patient and 5 control-group patients. The between-group differences in adverse reactions were significant (P<0.05).

Conclusions

The combination of DCs and CIK cells effectively treated malignant pericardial effusion, produced few side effects, and improved the patients’ quality of life.

Interleukin-15 enhances cytokine induced killer (CIK) cytotoxic potential against epithelial cancer cell lines via an innate pathway

CIK cells are a subset of effector lymphocytes endowed with a non-MHC restricted anti-tumor activity making them an appealing and promising cell population for adoptive immunotherapy. CIK are usually generated ex-vivo by initial priming with Interferon-γ (IFN-γ) and monoclonal antibody against CD3 (anti-CD3), followed by culture in medium containing Interleukin-2 (IL-2). Interleukin-15 (IL-15) shares with IL-2 similar biological functions and recently it has been reported to induce CIK with increased anti-leukemic potential. The aim of the study was to compare the killing efficacy of CIK generated by IL-2 alone or IL-2 and IL-15 toward tumor targets of different origins, leukemic cells and malignant cells from epithelial solid tumors. CIK bulk cultures were examined for cell proliferation, surface phenotype and cytotoxic potential against tumor cell lines K562, HL60, HeLa and MCF-7. The results showed that IL-15 is able to induce a selective expansion of CIK cells, but it is less effective in sustaining CIK cell proliferation compared to IL-2. Conversely, our data confirm and reinforce the feature of IL-15 to induce CIK cells with a potent cytotoxic activity mostly against tumor cells from epithelial solid malignancies via NKG2D-mediated mechanism.

Chemotherapy with or without autologous cytokine-induced killer cell transfusion as the first-line treatment for stage IV gastrointestinal cancer: a phase II clinical trial

OBJECTIVE

To investigate the efficacy of autologous cytokine-induced killer (CIK) cell therapy combined with chemotherapy versus chemotherapy alone for the treatment of stage IV gastrointestinal (GI) cancer in the first-line setting.

METHODS

Thirty-three patients diagnosed with stage IV GI cancer were divided into chemotherapy plus CIK group (chemo-CIK, n = 16) and chemotherapy-alone group (chemo-alone, n = 17). Autologous peripheral blood mononuclear cells were separated by flow cytometry, cultured in vitro to induce CIK cells, and transfused into patients on days 14 and 16 of the first and second chemotherapy cycles.

RESULTS

The median progression-free survival (PFS) was 5.6 months for patients in the chemo-CIK group and 3.83 months for those in the chemo-alone group. The difference was borderline significant (P = 0.06), indicating a potential advantage for combined CIK cell transfusion with chemotherapy in improving PFS. A favored objective response rate was also observed in the chemo-CIK group than in the chemo-alone group. This study also revealed that CIK cell transfusion restored the cellular immunity in these GI cancer patients. The percentage of natural killer T cells, NK cells, CD3(+) T cells, and T-cell subgroups CD4(+) proportion in the peripheral blood of cancer patients significantly increased after the CIK cell transfusion, while the change in T-cell subgroups CD8(+) and CD4(+)/CD8(+) did not differ significantly.

CONCLUSIONS

The study showed that the addition of CIK cell transfusion to traditional chemotherapy in the first-line setting was associated with a prolonged PFS and enhanced T-lymphocyte subset activity, supporting a potential treatment choice for advanced GI cancer patients.

Dendritic cell vaccine and cytokine-induced killer cell therapy for the treatment of advanced non-small cell lung cancer

The present study aimed to evaluate the survival time, immune response and safety of a dendritic cell (DC) vaccine and cytokine-induced killer (CIK) cell therapy (DC-CIK) in advanced non-small cell lung cancer (NSCLC). The present retrospective study enrolled 507 patients with advanced NSCLC; 99 patients received DC-CIK [immunotherapy group (group I)] and 408 matched patients did not receive DC-CIK, and acted as the control [non-immunotherapy group (group NI)]. Delayed-type hypersensitivity (DTH), quality of life (QOL) and safety were analyzed in group I. The follow-up period for the two groups was 489.2±160.4 days. The overall survival (OS) time was calculated using the Kaplan-Meier method. DTH was observed in 59 out of 97 evaluated patients (60.8%) and 67 out of 98 evaluated patients (68.4%) possessed an improved QOL. Fever and a skin rash occurred in 36 out of 98 patients (36.7%) and 7 out of 98 patients (7.1%) in group I. DTH occurred more frequently in patients with squamous cell carcinoma compared with patients with adenocarcinoma (77.1 vs. 40.4%; P=0.0013). Radiotherapy was not associated with DC-CIK-induced DTH (72.7 vs. 79.6%; P=0.18), but chemotherapy significantly reduced the rate of DTH (18.2 vs. 79.6%; P=0.00). The OS time was significantly increased in group I compared with group NI (P=0.03). In conclusion, DC-CIK may induce an immune response against NSCLC, improve the QOL, and prolong the OS time of patients, without adverse effects. Therefore, the present study recommends DC-CIK for the treatment of patients with advanced NSCLC.

Adjuvant Cytokine-Induced Killer Cell Therapy Improves Disease-Free and Overall Survival in Solitary and Nonmicrovascular Invasive Hepatocellular Carcinoma After Curative Resection

Cytokine-induced killer (CIK) cell therapy has recently been used as an adjuvant setting following resection of hepatocellular carcinoma (HCC), while its benefit remains unclear. This study aimed to evaluate the efficacy of adjuvant CIK application in solitary HCC patients undergoing curative resection with stratification of microvascular invasion (MVI).In total, specimens and data from 307 solitary HCC patients undergoing curative resection between January 2007 and December 2010 were included. Of these, 102 patients received CIK treatment after surgery (CIK group), whereas 205 patients did not (control group). Pathological evaluation was used to retrospectively determine MVI status. The CIK group had 60 MVI-negative and 42 MVI-positive patients, while the numbers in control group were 124 and 81. Kaplan-Meier and Cox regression analyses were used to validate possible effects of CIK treatment on disease free survival (DFS) and overall survival (OS) as appropriate.For all patients, the CIK group exhibited significantly higher OS than the control group (log-rank test; PDFS = 0.055, POS = 0.020). Further analysis based on MVI stratification showed that for patients with MVI, DFS and OS did not differ between the 2 groups (PDFS = 0.439, POS = 0.374). For patients without MVI, the CIK group exhibited better DFS and OS than the control group (PDFS = 0.042, POS = 0.007), and multivariate analyses demonstrated that CIK treatment was an independent prognostic factor both for DFS and OS.For solitary HCC, CIK cell therapy after curative resection improves DFS and OS for patients without MVI, but has no statistically significant survival benefit for patients with MVI.

Cytokine-induced killer (CIK) cells: from basic research to clinical translation

The accumulation of basic researches and clinical studies related to cytokine-induced killer (CIK) cells has confirmed their safety and feasibility in treating malignant diseases. This review summarizes the available published literature related to the biological characteristics and clinical applications of CIK cells in recent years. A number of clinical trials with CIK cells have been implemented during the progressive phases of cancer, presenting potential widespread applications of CIK cells for the future. Furthermore, this review briefly compares clinical applications of CIK cells with those of other adoptive immunotherapeutic cells. However, at present, there are no uniform criteria or large-scale preparations of CIK cells. The overall clinical response is difficult to evaluate because of the use of autologous CIK cells. Based on these observations, several suggestions regarding uniform criteria and universal sources for CIK cell preparations and the use of CIK cells either combined with chemotherapy or alone as a primary strategy are briefly proposed in this review. Large-scale, controlled, grouped, and multi-center clinical trials on CIK cell-based immunotherapy should be conducted under strict supervision. These interventions might help to improve future clinical applications and increase the clinical curative effects of CIK cells for a broad range of malignancies in the future.

Cytokine-induced killer cells co-cultured with dendritic cells loaded with the protein lysate produced by radiofrequency ablation induce a specific antitumor response

Radiofrequency ablation (RFA) causes coagulative necrosis of tumor tissue and the production of local tumor protein debris. These fragments of tumor protein debris contain a large number of various antigens, which can stimulate a specific cellular immune response. In the present study, dendritic cells (DCs) were loaded with tumor protein lysate antigens that were produced in situ by RFA, and were used to treat murine colon carcinoma in combination with cytokine-induced killer (CIK) cells. Subsequent to the treatment of murine colon carcinoma by RFA, the in situ supernatant of tumor lysis was collected and the DCs were loaded with the lysate antigen to generate Ag-DCs. CIK cells induced from the spleen cells of mice were co-cultured with Ag-DCs to generate Ag-DC-CIK cells. The results revealed that the Ag-DC-CIK cells exhibited strong antitumor activity in vitro and in vivo. The morphology and immunophenotypes of these cells were determined using microscopy and flow cytometry, respectively. The cytotoxic activity of Ag-DC-CIK cells was determined using a CCK-8 assay. To establish a mouse model, mice were randomized into Ag-DC-CIK, DC-CIK, CIK and PBS control groups and monitored for tumor growth and survival time. ANOVA was used to compare the trends in the three groups for implanted tumor volumes. The log-rank test was used to compare the survival time. The present findings indicated that DCs loaded with the protein lysate antigens of tumors, produced in situ by RFA, combined with CIK cells may be a novel strategy for cancer treatment.

A meta-analysis of cytokine-induced killer cells therapy in combination with minimally invasive treatment for hepatocellular carcinoma

BACKGROUND AND OBJECTIVE

There was a continuing controversy on whether the adoptive transfusion of cytokine-induced killer cells (CIK) therapy should have been recommended to reduce the recurrence and metastasis of hepatocellular carcinoma (HCC) after minimally invasive therapy such as TACE (transarterial chemoembolization) or TACE plus RFA (radiofrequency ablation) treatment. The meta-analysis was conducted to compare the effectiveness of CIK cells transfusion therapy combined with TACE or TACE plus RFA treatment with that of minimally invasive therapy alone.

METHODS

Relevant studies were identified by electronic search using a combination of "hepatocellular carcinoma" and "cytokine-induced killer cells". Overall survival (OS) rates and recurrence-free survival (RFS) rates were compared as the major outcome measures. The meta-analysis was divided into two sub-studies (sub-study 1: CIK+TACE+RFA versus TACE+RFA; sub-study 2: CIK+TACE versus TACE) to avoid the risk of bias as we could.

RESULTS

Meta-analysis data suggested that CIK cells transfusion therapy combined with TACE plus RFA treatment was associated with higher 1-year RFS rate (odds ratio [OR]=2.46) and 1-year, 2-year OS rates (OR: 1-year=2.09; 3-year=2.16) than TACE plus RFA treatment alone in sub-study 1. For sub-study 2, there were significant differences between CIK+TACE group and TACE group for OS rates (OR: half-year=3.29; 1-year=3.71; 2-year=7.37).

CONCLUSION

CIK cells transfusion therapy truly showed a synergistic effect for HCC patients after minimally invasive treatment especially for a long-term survival.

Common gamma chain (γc) cytokines differentially potentiate TNFR family signaling in antigen-activated CD8(+) T cells

Background

Several members of the common gamma chain (gc) cytokine family are already approved (IL-2) or actively being developed as vaccine adjuvants and cancer immunotherapies. Studies have indicated that co-administration of gc cytokines may enhance the efficacy of immunotherapies that function via direct activation of co-stimulatory T cell receptors. To define the specific influence of gc cytokines on the co-stimulatory capacity of CD8⁺ T cells and identify combinations with synergistic potential, we investigated the direct impact of gc cytokines on the differentiation and transcriptional profile of recently antigen-primed CD8⁺ T cells.

Methods

Naïve CD8⁺ T cells were activated with peptide-pulsed APCs. After 48 hours, CD8⁺ T cells were harvested and re-cultured in media supplemented with IL-2, IL-4, IL-7, IL-15 or IL-21. After 24 hours, cells were analyzed by cytokine bead array, flow cytometry, and mRNA micro-array. Gene networks responsible for specific CD8⁺ T cell functions were constructed through literature-meta review and publicly available annotation databases. Gene expression data from the experimental groups was imported into this network to visualize the impact of each gc cytokine on the functional polarization of recently-activated CD8⁺ T cells.

Results

Among the gc cytokines, IL-2 induced the greatest increase in the expression of co-stimulatory receptors in recently-activated CD8⁺ T cells. IL-2 increased significantly expression of 4-1BB, GITR, ICOS and OX40, at both the transcriptional and protein level. IL-2 also drove the greatest increase in cellular proliferation and the most robust shift towards a pro-survival phenotype, compared with the other gc cytokines. Both IL-4 and IL-21 enhanced expression of cytotoxic effector proteins, but drove distinct phenotypic polarizations, Th2/Tc2 and NK-like, respectively.

Conclusions

Overall, these observations suggest that among gc cytokines, IL-2 may be uniquely capable of synergizing with therapeutic strategies that combine immunization with agonists of co-stimulatory T cell receptors. Previous studies have shown that the timing of IL-2 treatment relative to immunization plays a key role in defining the CD8⁺ T cell response, and the findings from this study indicate that administration of exogenous IL-2 shortly after the initial antigen-priming event has concluded may augment the receptivity of these cells to subsequent TNFR co-stimulation.

Evaluation of tumor response to cytokine-induced killer cells therapy in malignant solid tumors

CIK cells therapy has been evaluated as an adoptive cell immunotherapy for cancer patients, but there still have not been any standardized systems for evaluating the antitumor efficacy yet. The WHO and RECIST criteria have already been established for a few years but not sufficient to fully characterize the activity of immunotherapy. Based on these two criteria, the irRC was proposed for evaluating the efficacy of immunotherapy. A variety of bioassays for immune monitoring including the specific and non-specific methods, have been established. We recommend detect levels of various immunocytes, immune molecules and soluble molecules to find the correlations among them and clinicopathological characteristics to establish criteria for immunological classification. We also recommend a paradigm shift for the oncologists in the evaluation of immune therapies to ensure assessment of activity based on clinically relevant criteria and time points.

Global transcriptome-wide analysis of CIK cells identify distinct roles of IL-2 and IL-15 in acquisition of cytotoxic capacity against tumor

Background

Cytokine-induced killer (CIK) cells are an emerging approach of cancer treatment. Our previous study have shown that CIK cells stimulated with combination of IL-2 and IL-15 displayed improved proliferation capacity and tumor cytotoxicity. However, the mechanisms of CIK cell proliferation and acquisition of cytolytic function against tumor induced by IL-2 and IL-15 have not been well elucidated yet.

Methods

CIK_IL-2 and CIK_IL-15 were generated from peripheral blood mononuclear cells primed with IFN-γ, and stimulated with IL-2 and IL-15 in combination with OKT3 respectively. RNA-seq was performed to identify differentially expressed genes, and gene ontology and pathways based analysis were used to identify the distinct roles of IL-2 and IL-15 in CIK preparation.

Results

The results indicated that CIK_IL-15 showed improved cell proliferation capacity compared to CIK_IL-2. However, CIK_IL-2 has exhibited greater tumor cytotoxic effect than CIK_IL-15. Employing deep sequencing, we sequenced mRNA transcripts in CIK_IL-2 and CIK_IL-15. A total of 374 differentially expressed genes (DEGs) were identified including 175 up-regulated genes in CIK_IL-15 and 199 up-regulated genes in CIK_IL-2. Among DEGs in CIK_IL-15, Wnt signaling and cell adhesion were significant GO terms and pathways which related with their functions. In CIK_IL-2, type I interferon signaling and cytokine-cytokine receptor interaction were significant GO terms and pathways. We found that the up-regulation of Wnt 4 and PDGFD may contribute to enhanced cell proliferation capacity of CIK_IL-15, while inhibitory signal from interaction between CTLA4 and CD80 may be responsible for the weak proliferation capacity of CIK_IL-2. Moreover, up-regulated expressions of CD40LG and IRF7 may make for improved tumor cytolytic function of CIK_IL-2 through type I interferon signaling.

Conclusions

Through our findings, we have preliminarily elucidated the cells proliferation and acquisition of tumor cytotoxicity mechanism of CIK_IL-15 and CIK_IL-2. Better understanding of these mechanisms will help to generate novel CIK cells with greater proliferation potential and improved tumor cytolytic function.

SMAC Mimetic BV6 Enables Sensitization of Resistant Tumor Cells but also Affects Cytokine-Induced Killer (CIK) Cells: A Potential Challenge for Combination Therapy

Allogeneic hematopoietic stem cell transplantation (HSCT) is an established treatment option for high-risk hematological malignancies, and may also be offered to patients with solid malignancies refractory to conventional therapies. In case of patients' relapse, refractory tumor cells may then be targeted by cellular therapy-based combination strategies. Here, we investigated the potential of small molecule IAP (SMAC mimetic) BV6 in increasing cytokine-induced killer (CIK) cell-mediated cytotoxicity against different tumor targets. Four-hour pre-incubation with 2.5 μMol BV6 moderately enhanced CIK cell-mediated lysis of hematological (H9, THP-1, and Tanoue) and solid malignancies (RH1, RH30, and TE671). However, BV6 also increased apoptosis of non-malignant cells like peripheral blood mononuclear cells and most notably had an inhibitory effect on immune cells potentially limiting their cytotoxic potential. Hence, cytotoxicity increased in a dose-dependent manner when BV6 was removed before CIK cells were added to tumor targets. However, cytotoxic potential was not further increasable by extending BV6 pre-incubation period of target cells from 4 to 12 h. Molecular studies revealed that BV6 sensitization of target cells involved activation of caspases. Here, we provide evidence that SMAC mimetic may sensitize targets cells for CIK cell-induced cell death. However, BV6 also increased apoptosis of non-malignant cells like CIK cells and peripheral mononuclear cells. These findings may therefore be important for cell- and small molecule IAP-based combination therapies of resistant cancers after allogeneic HSCT.

Toll-like receptor 4 is required for the cytotoxicity of cytokine-induced killer cells

Cytokine-induced killer (CIK) cells are heterogeneous effector T cells with diverse T-cell receptor specificities with non-major histocompatibility complex-restricted cytolytic activities against tumor cells and are considered a promising therapeutic approach against hematologic malignancy. Recently, it has been reported that IL-15-activated CIK cells are superior to cells generated according to the standard protocol; however, the underlying mechanism remains to be elucidated. In the present study, we found that in IL-15-stimulated CIK cells, Toll-like receptor 4 (TLR4) expression was upregulated. Upon knockdown of TLR4, the cytolytic activity was considerably compromised. Re-expression of TLR4 in CIK cells restored their function, confirming the essential role of TLR4 in CIK cell cytotoxicity. Collectively, our study demonstrated that TLR4 was essential for the cytotoxicity of CIK cells against tumor cells, which might provide a novel approach to promote the therapeutic efficacy of CIK cells against hematologic malignancy.

The CIK cells stimulated with combination of IL-2 and IL-15 provide an improved cytotoxic capacity against human lung adenocarcinoma

Generation of cytokine-induced killer (CIK) cells is an emerging approach in adoptive donor lymphocyte infusion for patients with a wide range of tumors. However, our previous in vitro studies have shown that the killing efficacy of CIK cells against lung cancer was lower than other tumor cells, while the underlying mechanisms are not clear. We explored the feasibility to improve CIK cells mediated cytotoxicity against lung cancer. Interleukin (IL)-15 is a pleiotropic cytokine that stimulates cytolytic activity and cytokine secretion of NK cells, which may enhance the cytotoxic activity of CIK cells. In this study, we intended to stimulate the CIK cells by IL-2 in combination with IL-15 in cell expansion to achieve enhanced cytotoxicity against lung cancer cells. The different phenotypes of IL-2 or combination of IL-2 and IL-15 stimulated cytokine-induced killer cells were determined, and the improved cytotoxicity of IL-2 and IL-15 induced CIK cells against lung adenocarcinoma were evaluated both in vitro and in vivo. CIK cells stimulated with both IL-2 and IL-15 has shown greater proliferative potential than CIK cells treated with IL-2 alone. IL-15 induction also has driven the expansion of CD3+CD56+ subset and significantly enhanced cytotoxicity against tumor cells. Further analysis has demonstrated that CIKIL-2&IL-15 injected mice models have shown significant tumor regression and lower expression level of CyclinD1 in tumor tissue. This study has provided preclinical evidences that CIKIL-2&IL-15 with enhanced cytotoxicity may offer alternative treatment option for patients with lung cancer.

Acute myeloid leukemia and novel biological treatments: monoclonal antibodies and cell-based gene-modified immune effectors

In the context of acute myeloid leukemia (AML) treatment, the interface between chemotherapy and immunotherapy is at present getting closer as never before. Scientific research is oriented in overcoming the main limits of actual chemotherapeutic regimens against AML, which still accounts for a considerable number of relapsed or resistant forms. A lot of investments have been done in the use of monoclonal antibodies (mAbs) and recently gene-modified immune cells have been considered as an alternative approach whenever chemotherapy fails to eradicate the disease. In this sense, AML is a potential suitable target for immunotherapeutic approaches, due to overexpression of several tumor antigens. Here we describe the state of the art of mAbs and cellular therapies employing engineered immune effectors, developed against specific AML antigens, in a window embracing preclinical research and translational studies to the clinical setting.

The phenotype of ex vivo generated cytokine-induced killer cells is associated with overall survival in patients with cancer

Cytokine-induced killer (CIK) cells are ex vivo generated heterogeneous NK-like T lymphocytes. It is not very clear whether the phenotype of CIK cells is associated with their therapeutic efficacy to cancer patients. Thus, in this study, the association of phenotype of CIK cells and the overall survival of 121 patients with hepatocellular carcinoma (HCC), 74 patients with lung cancer and 42 patients with colorectal cancer, all of whom underwent surgical resection and received autogenous CIK cell therapy, was analyzed. We found that high ratio of the CD3+CD4+ subset was associated with poorer overall survival in colorectal cancer, but not HCC or lung cancer. A high ratio of the CD3+CD8+ subset was associated with improved overall survival in all three types of cancer. A high ratio of the CD3+CD56+ NK-like subset was associated with improved overall survival in lung and colorectal cancer, but not HCC. A high ratio of the CD3-CD56+ NK subset was associated with poorer overall survival in lung and colorectal cancer, but not HCC. In conclusion, the CD3+CD8+ and CD3+CD56+ subsets, especially the CD3+CD8+ subset, may be the major phenotypes responsible for anti-tumor immunity in vivo after autogenous CIK cell therapy.

Early efficacy of stereotactic body radiation therapy combined with adoptive immunotherapy for advanced malignancies

Stereotactic body radiation therapy (SBRT) concentrates radiation to a predefined target, affecting all the cells within it. Adoptive immunotherapy is not restricted by the major histocompatibility complex (MHC) in recognizing and eliminating target cells. We investigated the effects of the combined modality of SBRT and adoptive immunotherapy on patients with advanced malignant tumors. The database of 316 patients with 845 tumors who underwent SBRT between April, 2010 and February, 2012 was retrospectively reviewed. Of the 316 patients, 145 received biological immunotherapy and were assigned into the observation group, whereas the remaining patients constituted the control group. Patients in the two groups were recorded on efficacy assessment, Karnofsky performance status (KPS), cell phenotype expression level in vitro and the percentages of lymphocyte subsets and ratio of CD4⁺/CD8⁺ lymphocytes in the peripheral blood. Following treatment, the total effectiveness [complete response (CR) + partial response (PR)], the KPS score, the percentages of lymphocyte subsets and the CD4⁺/CD8⁺ lymphocyte ratio in the observation group were higher compared to those in the control group, with a statistically significant difference (P<0.05). The expression of CD3⁺ and CD3⁺CD56⁺ cytokine-induced killer (CIK) cells were increased from 56.76±4.54% and 11.32±2.96% to 94.67±4.46% and 32.65±1.12%, respectively, when cultured in vitro (P<0.01). The percentages of lymphocyte subsets and the CD4⁺/CD8⁺ lymphocyte ratio were significantly increased compared to prior to treatment in the observation group (P<0.05). SBRT combined with adoptive immunotherapy may be a novel therapeutic option for patients with advanced malignant tumors.

Targeting of acute myeloid leukaemia by cytokine-induced killer cells redirected with a novel CD123-specific chimeric antigen receptor

Current therapeutic regimens for acute myeloid leukaemia (AML) are still associated with high rates of relapse. Immunotherapy with T-cells genetically modified to express chimeric antigen receptors (CARs) represents an innovative approach. Here we investigated the targeting of the interleukin three receptor alpha (IL3RA; CD123) molecule, which is overexpressed on AML bulk population, CD34(+) leukaemia progenitors, and leukaemia stem cells (LSC) compared to normal haematopoietic stem/progenitor cells (HSPCs), and whose overexpression is associated with poor prognosis. Cytokine-induced killer (CIK) cells were transduced with SFG-retroviral-vector encoding an anti-CD123 CAR. Transduced cells were able to strongly kill CD123(+) cell lines, as well as primary AML blasts. Interestingly, secondary colony experiments demonstrated that anti-CD123.CAR preserved in vitro HSPCs, in contrast to a previously generated anti-CD33.CAR, while keeping an identical cytotoxicity profile towards AML. Furthermore, limited killing of normal monocytes and CD123-low-expressing endothelial cells was noted, thus indicating a low toxicity profile of the anti-CD123.CAR. Taken together, our results indicate that CD123-specific CARs strongly enhance anti-AML CIK functions, while sparing HSPCs and normal low-expressing antigen cells, paving the way to develop novel immunotherapy approaches for AML treatment.

Enhancing cytokine-induced killer cell therapy of multiple myeloma

Cytokine-induced killer (CIK) cells are in clinical testing against various tumor types, including multiple myeloma. In this study, we show that CIK cells have activity against subcutaneous and disseminated models of human myeloma (KAS-6/1), which can be enhanced by infecting the CIK cells with an oncolytic measles virus (MV) or by pretreating the myeloma cells with ionizing radiation (XRT). KAS-6/1 cells were killed by coculture with CIK or MV-infected CIK (CIK/MV) cells, and the addition of an anti-NKG2D antibody inhibited cytolysis by 50%. However, human bone marrow stromal cells can reduce CIK and CIK/MV mediated killing of myeloma cells (RPMI 8226, JJN-3 and MM1). In vivo, CIK and CIK/MV prolonged the survival of mice with systemic myeloma, although CIK/MV showed enhanced antitumor activity compared with CIK. Irradiation of the KAS-6/1 cells induced mRNA and protein expression of NKG2D ligands, MICA, and MICB in a dose-dependent manner and enhanced delivery of CIK/MV to the irradiated tumors. In both subcutaneous and disseminated myeloma models, XRT at 2 Gy resulted in superior prolongation of the survival of mice given CIK/MV therapy compared with CIK/MV with no XRT. This study demonstrates the potential of CIK against myeloma and that the combination of virotherapy with radiation could be used to further enhance therapeutic outcome using CIK cells.

In vivo distribution and antitumor effect of infused immune cells in a gastric cancer model

Adoptive cellular transfer has been employed for cancer immunotherapy, including patients with gastric cancer. However, little is known about the distribution of effector cells after their injection via different pathways. In this study, we used human gastric cancer cells (BGC823) tagged with enhanced green fluorescent protein (EGPF) to establish a subcutaneous gastric cancer model in nude mice. Cytokine-induced killer (CIK) cells and cytotoxic T lymphocytes (CTLs) were generated from human peripheral blood and labeled with red fluorescent PKH26. A portion of CIK cells was armed with CEA/CD3-bispecific single-chain antibody. When CIK cells were injected into nude mice with established subcutaneous gastric cancer via peritumoral (p.t.), intravenous (i.v.) and intraperitoneal (i.p.) infusion respectively, the distribution of cells was observed using a live fluorescence imaging system. We found that only a very small number of CIK cells could travel to the tumor site after i.p. or i.v. infusion, and they inhibited subcutaneous tumor growth in vivo only immediately following injection. In contrast, p.t. injection resulted in a significantly higher accumulation of CIK cells at the tumor site for 48 hours and mediated the greatest tumor inhibition compared with the other two injection methods. In addition, we compared the antitumor activity of CIK, CEA/CD3-bscAb-CIK and CTL cells in vitro and in vivo after p.t. injection. Among the three types of immune cells, CTLs demonstrated the strongest antitumor activity both in vitro and in vivo. CEA/CD3-bispecific single chain antibody could effectively link T lymphocytes and tumor cells expressing CEA, and resulted in significantly higher accumulation of CIK cells at the tumor site compared with the parental CIK cells. This study indicates that peritumoral injection of immune effector cells by minimally invasive surgical procedures represents an effective delivery method of adoptive cellular immunotherapy. Tumor-specific immune cells, such as CTLs, are a better choice of effector cells than CIKs in cellular immunotherapy. Furthermore, CD3+ immune cells armed with the CEA/CD3-bispecific single chain antibody could more effectively travel to and accumulate at the site of tumors expressing CEA, such as gastric cancer.

Adoptive immunotherapy in postoperative hepatocellular carcinoma: a systemic review

PURPOSE

The effectiveness of immunotherapy for postoperative hepatocellular carcinoma patients is still controversial. To address this issue, we did a systemic review of the literatures and analyzed the data with emphasis on the recurrence and survival.

METHODS

We searched six randomized controlled trials that included adoptive immunotherapy in the postoperative management of hepatocellular carcinoma and compared with non-immunotherapy postoperation. A meta-analysis was carried out to examine one- and 3-year recurrence and survival.

RESULTS

The overall analysis revealed significantly reduced risk of 1-year recurrence in patients receiving adoptive immunotherapy (OR=0.35; 95% CI, 0.17 to 0.71; p=0.003), in that the risk of 3-year recurrence with a pooled OR estimated at 0.31 (95% CI 0.16 to 0.61; p=0.001). However, no statistically significant difference was observed for 3-year survival between groups with adoptive immunotherapy and without adjuvant treatment (OR=0.91; 95% CI, 0.45 to 1.84; P=0.792).

CONCLUSIONS

Adjuvant immunotherapy with cytokine induced killer cells or lymphokine activated killer cells may reduce recurrence in postoperative hepatocellular carcinoma patients, but may not improve survival.

Review of Chinese clinical trials on CIK cell treatment for malignancies

China is the country where the most clinical trials on CIK cells have been performed. We aimed to provide definite evidence for using CIK cell treatment and extrapolate a common applicative standard for malignancies. We chose the VIP database of Chinese scientific and technological journals to search the literature. We entered the keywords "CIK" or "xi bao yin zi you dao de sha shang xi bao" (the equivalent Chinese phrase for CIK cells, by Chinese characters) and searched for in vivo human trials. In 24 collected trials, 936 patients were treated with CIK cells, 525 men and 246 women. The cultivation time of CIK cells ranged from 7 to 28 days. In five studies, CIK cells were co-cultured with dendritic cells. The total number of CIK cells used ranged from 6×10(6) to 1.5×10(10). The total number of DC-CIK cells used ranged from 1×10(9) to 1.3×10(10). In all studies, those immune parameters and tumour markers examined increased, but not all increased significantly. Of the reported 563 patients, 40 had a complete response, 126 had a partial response, 125 had a minimal response, 135 had stable disease and 58 had progressive disease. The remaining 76 patients did not reach an objective response. The total response rate was 51.7% (291/563). The toxicities were slight. CIK cell treatment is a promising and safe modality for treating malignancies. We proposed a standard for cultivating CIK cells.

Dynamic tracing of immune cells in an orthotopic gastric carcinoma mouse model using near-infrared fluorescence live imaging

Adoptive cellular immunotherapy (ACI) has been demonstrated to be a promising cancer therapeutic, however, the distribution of immune cells injected into a tumor-bearing body is unclear. In this study, we investigated the tumor-targeting capacity of cytokine-induced killer (CIK) cells and cytotoxic T lymphocytes (CTLs) in a human gastric carcinoma orthotopic mouse model using a near-infrared fluorescence imaging system. CIK cells and tumor-specific CTLs were prepared with the near-infrared fluorescent dye DiR. As expected, no significant change in the proliferation rate or antitumor activity of CIK cells and CTLs was noted after labeling with DiR. Furthermore, a gastric carcinoma orthotopic model was established using a fibrinogen-thrombin method in nude mice followed by intraperitoneal infusion of the labeled immune cells into nude mice with established gastric carcinoma. Dynamic tracing of the immune cells was performed using a fluorescence-based live imaging system. Concentrated fluorescence signals were observed for a minimum of two weeks at the tumor site in mice infused with either CIK cells or CTLs with a peak signal at 48 h. Notably, CTLs were more persistent at the tumor site and exhibited a more intense antitumor activity than CIK cells following infusion. These results provided visual evidence of the tumor-targeting capacity of immune cells in live animals.

Cytokine-induced killer (CIK) cell therapy for patients with hepatocellular carcinoma: efficacy and safety

Purpose

To evaluate the efficacy of cytokine-induced killer (CIK) cell therapy in the treatment of hepatocellular carcinoma.

Materials and methods

Randomized phase II and III trials on CIK cell-based therapy were identified by electronic searches using a combination of "hepatocellular carcinoma" and "cytokine-induced killer cells".

Results

The analysis showed significant survival benefit (one-year survival, p < 0.001; two-year survival, p < 0.001; median overall survival, p < 0.001) in favor of CIK-based therapy. Comparison of CIK group versus non-CIK group resulted in a significantly prolonged progression-free survival (PFS) (p < 0.01). A favored disease control rate (DCR) and overall response rate (ORR) were also observed in patients receiving CIK cell therapy (p < 0.01). Meanwhile, patients in the CIK group showed better quality of life (QoL), diminished HBV-DNA content and AFP level (p < 0.01). Comparing T-lymphocyte subsets in peripheral blood, the analysis showed the ratio of CD3⁺, CD4⁺, CD4⁺CD8⁺ and CD3⁺CD4⁺ T cells significantly increased in the CIK group, compared with the non-CIK group (p < 0.01).

Conclusions

CIK cell therapy demonstrated a significant superiority in prolonging the median overall survival, PFS, DCR, ORR and QoL of HCC patients. These results support further larger scale randomized controlled trials for HCC patients with or without the combination of other therapeutic methods.

Cytokine-induced killer (CIK) cells as feasible and effective adoptive immunotherapy for the treatment of solid tumors

INTRODUCTION

Cytokine-induced killer (CIK) cells are heterogeneous ex vivo-expanded T lymphocytes with mixed T-NK phenotype and endowed with a wide MHC-unrestricted antitumor activity. CIK cells can be expanded from peripheral blood mononuclear cells (PBMC) cultured with the timed addition of IFN-γ, Ab anti-CD3 and IL2. A consistent subset of mature CIK cells presents a CD3(+)CD56(+) phenotype. The CD3(+)CD56(+) cellular subset is the main responsible for the tumor-killing activity, mostly mediated by the interaction of NKG2D receptor with MHC-unrestricted ligands (MIC A/B; ULBPs) on tumor cells.

AREAS COVERED

In the present work, we described the biologic characteristics of CIK cells, focusing on those aspects that may favor their clinical translation. We reviewed preclinical data and analyzed reports from clinical trials. A specific paragraph is dedicated to future research perspectives in the field.

EXPERT OPINION

CIK cells represent a realistic new option in the field of cancer immunotherapy. Crucial issues, favoring their clinical translation, are the easy availability of large amounts of expanded CIK cells and their MHC-unrestricted tumor killing, potentially effective against many tumor types. Intriguing future perspectives and open challenges are the investigation of synergisms with other immunotherapy approaches, targeted therapies or even conventional chemotherapy.

New adoptive immunotherapy strategies for solid tumours with CIK cells

INTRODUCTION

Despite development and introduction of new and innovative drugs, a large number of malignant diseases are associated with unfavourable prognosis. In recent years, considerable progress in cancer treatment has been obtained by the application of cytokine-induced killer (CIK) cells.

AREAS COVERED

This review provides an overview and summary of recent advances in adoptive immunotherapy strategies in cancer treatment using CIK cells. A selective literature search has been performed.

EXPERT OPINION

The application of CIK cells as adoptive immunotherapy plays an important role in cancer treatment. Combining CIK cells with other conventional and established therapy options represents an innovative approach and will hopefully provide new insight for the future.

Cytokine-induced killer cells in the treatment of patients with solid carcinomas: a systematic review and pooled analysis

BACKGROUND AIMS

The aim of this study was to evaluate the efficacy and safety of cytokine-induced killer (CIK) cell therapy for solid carcinomas.

METHODS

We performed a computerized search of phase II/III clinical trial databases of CIK cell-based therapy using a combination of the terms 'cytokine-induced killer cells', 'tumor' and 'cancer'.

RESULTS

Treatment with CIK cells was associated with a significantly improved half-year survival (P = 0.003), 1-year survival (P = 0.0005), 2-year survival (P < 0.01) and mean survival time (MST) (P < 0.001). Patients in the CIK group showed a prolonged half-year progression-free survival (PFS) (P < 0.01), 1-year PFS (P < 0.01) and median time to progression (MTTP) (P < 0.001). A favored disease control rate (DCR) was observed in patients receiving CIK cell therapy, while the objective response rate (ORR) was not altered (P = 0.05) compared with the non-CIK group (P = 0.007). CIK cell therapy could also reduce the adverse effects of grade III and IV leukopenia caused by chemotherapy (P = 0.002) and diminish hepatitis B virus (HBV)-DNA content (P < 0.01). However, the incidence of fever in the CIK therapy group was significantly higher than in the non-CIK group (P = 0.02). The percentage of CD3(+), CD4(+), CD4(+)CD8(+), CD3(-) CD56(+) and CD3(+) CD56(+) T-lymphocyte subsets in the peripheral blood of cancer patients was significantly increased, whereas the percentage of CD8(+) T-lymphocyte cells was significantly decreased in the CIK group compared with the non-CIK group (P < 0.01).

CONCLUSIONS

CIK cell therapy has demonstrated a significant superiority in prolonging the MST, PFS, DCR and quality of life (QoL) of patients.

The cytotoxic potential of interleukin-15-stimulated cytokine-induced killer cells against leukemia cells

BACKGROUND AIMS

Cytokine-induced killer (CIK) cells may serve as an alternative approach to adoptive donor lymphocyte infusions (DLI) for patients with acute leukemia relapsing after haplo-identical hematopoietic stem cell transplantation (HSCT). We investigated the feasibility of enhancing CIK cell-mediated cytotoxicity by interleukin (IL)-15 against acute myeloid and lymphoblastic leukemia/lymphoma cells.

METHODS

CIK cells were activated using IL-2 (CIK(IL-2)) or IL-15 (CIK(IL-15)) and phenotypically analyzed by fluorescence-activated cell sorting (FACS). Cytotoxic potential was measured by europium release assay.

RESULTS

CIK(IL-2) cells showed potent cytotoxicity against the T-lymphoma cell line H9, T-cell acute lymphoblastic leukemia (T-ALL) cell line MOLT-4 and subtype M4 acute myeloid leukemia (AML) cell line THP-1, but low cytotoxicity against the precursor B (pB)-cell ALL cell line Tanoue. IL-15 stimulation resulted in a significant enhancement of CIK cell-mediated cytotoxicity against acute lymphoblastic leukemia/lymphoma cell lines as well as against primary acute myeloid and defined lymphoblastic leukemia cells. However, the alloreactive potential of CIK(IL-15) cells remained low. Further analysis of CIK(IL-15) cells demonstrated that the NKG2D receptor is apparently involved in the recognition of target cells whereas killer-cell immunoglobulin-like receptor (KIR)-HLA mismatches contributed to a lesser extent to the CIK(IL-15) cell-mediated cytotoxicity. In this context, CD3 (+) CD8 (+) CD25 (+) CD56(-) CIK(IL-15) cell subpopulations were more effective in the lysis of AML cells, in contrast with CD56 (+) CIK(IL-15) cells, which showed the highest cytotoxic potential against ALL cells.

CONCLUSIONS

This study provides the first evidence that CIK(IL-15) cells may offer a therapeutic option for patients with refractory or relapsed leukemia following haplo-identical HSCT.

New advances in leukaemia immunotherapy by the use of Chimeric Artificial Antigen Receptors (CARs): state of the art and perspectives for the near future

Leukaemia immunotherapy represents a fascinating and promising field of translational research, particularly as an integrative approach of bone marrow transplantation. Adoptive immunotherapy by the use of donor-derived expanded leukaemia-specific T cells has showed some kind of clinical response, but the major advance is nowadays represented by gene manipulation of donor immune cells, so that they acquire strict specificity towards the tumour target and potent lytic activity, followed by significant proliferation, increased survival and possibly anti-tumour memory state. This is achieved by gene insertion of Chimeric T-cell Antigen Receptors (CARs), which are artificial molecules containing antibody-derived fragments (to bind the specific target), joined with potent signalling T-Cell Receptor (TCR)-derived domains that activate the manipulated cells. This review will discuss the main application of this approach particularly focusing on the paediatric setting, raising advantages and disadvantages and discussing relevant perspectives of use in the nearest future.

Is adoptive T-cell therapy for solid tumors coming of age?

Among the novel biological therapeutics that will increase our ability to cure human cancer in years to come, adoptive cellular therapy is one of the most promising approaches. Although this is a complex and challenging field, there have been major advances in basic and translational research resulting in clinical trial activity that is now beginning to confirm this promise. The results obtained with tumor-infiltrating lymphocytes therapy for melanoma, and virus-specific CTLs for EBV-associated malignancies are encouraging in terms of both ability to obtain clinical benefit and limited toxicity profile. In both settings, objective responses were obtained in at least 50% of treated patients. However, improvements to the clinical protocols, in terms of better patient selection and timing of administration, as well as cell product quality and availability, are clearly necessary to further ameliorate outcome, and logistical solutions are warranted to extend T-cell therapy beyond academic centers. In particular, there is a need to simplify cell production, in order to decrease costs and ease preparation. Promising implementations are underway, including harnessing the therapeutic potential of T cells transduced with TCRs directed against shared tumor antigens, and delineating strategies aimed at targeting immune evasion mechanisms exerted by tumor cells.

Modulation of NKG2D-ligand cell surface expression enhances immune cell therapy of cancer

A variety of immune cell therapies proposed for use in the treatment of cancer, including both autologous cells (Lymphokine Activated Killer, Cytokine Induced Killer) or cell lines (TALL-104, NK-92), rely on recognition of NKG2D ligands on malignant cells for targeting. These ligands, such as MICA and MICB in humans are stress response ligands and are commonly, but not ubiquitously expressed within tumors. Several tumor escape mechanisms have been reported, including ligand downregulation and internalization, or proteolytic cleavage and shedding of their exposed portions (releasing soluble MICA and MICB; sMICA, sMICB). Therefore, an ability to prescreen patients for the level of tumor cell surface expression and shedding of these ligands would prevent needless treatment of patients that are unable to respond, whereas targeted pretreatment of patients to increase surface expression and/or block shedding would enhance the subsequent effectiveness of these therapies. Here, we report that serum tests of sMICA and sMICB in conjunction with tumor measurements might be used to determine rates of shedding from a tumor and that treatment with a selected combination of histone deacetylase inhibitors (to upregulate cell surface MICA/B in some tumors), and metalloproteinase inhibitors (to block MICA/B shedding in others) can be incorporated to regulate cell surface MICA/B levels before immune cell therapy, significantly enhancing their effectiveness (either used alone or as carrier vehicles for oncolytic viruses). Ultimately prescreening patients undergoing such immune cell therapies might be used to personalize cancer treatment regimens based on the NKG2D-ligand status of the tumor.

Immunotherapeutic Intervention against Sarcomas

Advances in systemic therapy for sarcoma have produced, over the last two decades, relatively short-term benefits for the majority of patient. Among the novel biologic therapeutics that will likely increase our ability to cure human cancer in the years to come, immunotherapy is one of the most promising approaches. While past attempts to use immunotherapy have failed to dramatically shift the paradigm of care for the treatment of patients with sarcoma, major advances in basic and translational research have resulted, in more recent years, in clinical trial activity that is now beginning to generate promising results. However, to move from “proof of principle” to large scale clinical applicability, we need well-designed, multi-institutional clinical trials, along with continuous laboratory research to explore further the immunological characteristics of individual sarcoma subtypes and the consequent tailoring of therapy.

Emerging natural killer cell immunotherapies: large-scale ex vivo production of highly potent anticancer effectors

Natural killer (NK) cell therapies are emerging worldwide as promising anticancer treatments, exploiting the fast cytolytic action of NK effectors and their potentially broad applicability against a wide range of malignancies. Until recently, clinical protocols have mainly involved freshly isolated NK cells or short- term activated NK cells or lymphokine-activated killer (LAK) cells. However, overall effector numbers and their anticancer potencies remained restricted, which poses a limiting factor to clinical efficacy. Recent developments in the field aim to improve clinical trial designs by increasing effector to target cell ratios in vivo and by application of superior cytotoxic NK effectors. Large-scale production of clinical grade NK cells through long-term activation in ex vivo cultures are another novel means in achieving these goals. However, such procedures require compliance with the strict Good Manufacturing Practice (GMP) regulations to ensure quality and safety of the NK cell product. Although the overall number of new protocols still remains comparably low, some of the protocols are already translated into clinical use. Also striking is the diversity of the different protocols proposed. We highlight in this review the most recent developments in the NK cell field with a focus on long-term NK cell expansion. Critical issues relating to this novel and promising type of therapy are highlighted and discussed.

Thymoglobulin, interferon-γ and interleukin-2 efficiently expand cytokine-induced killer (CIK) cells in clinical-grade cultures

Background

Cytokine-induced killer (CIK) cells are typically differentiated in vitro with interferon (IFN)-γ and αCD3 monoclonal antibodies (mAb), followed by the repeated provision of interleukin (IL)-2. It is presently unknown whether thymoglobulin (TG), a preparation of polyclonal rabbit γ immunoglobulins directed against human thymocytes, can improve the generation efficiency of CIK cells compared with αCD3 mAb in a clinical-grade culture protocol.

Methods

Peripheral blood mononuclear cells (PBMC) from 10 healthy donors and 4 patients with solid cancer were primed with IFN-γ on day 0 and low (50 ng/ml), intermediate (250 ng/ml) and high (500 ng/ml) concentrations of either αCD3 mAb or TG on day 1, and were fed with IL-2 every 3 days for 21 days. Aliquots of cells were harvested weekly to monitor the expression of representative members of the killer-like immunoglobulin receptor (KIR), NK inhibitory receptor, NK activating receptor and NK triggering receptor families. We also quantified the frequency of bona fide regulatory T cells (Treg), a T-cell subset implicated in the down-regulation of anti-tumor immunity, and tested the in vitro cytotoxic activity of CIK cells against NK-sensitive, chronic myeloid leukaemia K562 cells.

Results

CIK cells expanded more vigorously in cultures supplemented with intermediate and high concentrations of TG compared with 50 ng/ml αCD3 mAb. TG-driven CIK cells expressed a constellation of NK activating/inhibitory receptors, such as CD158a and CD158b, NKp46, NKG2D and NKG2A/CD94, released high quantities of IL-12p40 and efficiently lysed K562 target cells. Of interest, the frequency of Treg cells was lower at any time-point compared with PBMC cultures nurtured with αCD3 mAb. Cancer patient-derived CIK cells were also expanded after priming with TG, but they expressed lower levels of the NKp46 triggering receptor and NKG2D activating receptor, thus manifesting a reduced ability to lyse K562 cells.

Conclusions

TG fosters the generation of functional CIK cells with no concomitant expansion of tumor-suppressive Treg cells. The culture conditions described herein should be applicable to cancer-bearing individuals, although the differentiation of fully functional CIK cells may be hindered in patients with advanced malignancies.