Expansion of cytotoxic CD3+ CD56+ cells from peripheral blood progenitor cells of patients undergoing autologous hematopoietic cell transplantation

Cytokine-Induced Killer Cell Immunotherapy Reduces Recurrence in Patients with Early-Stage Hepatocellular Carcinoma

BACKGROUND/OBJECTIVES

Cytokine-induced killer (CIK) cell immunotherapy has shown promise in reducing recurrence and improving survival outcomes in hepatocellular carcinoma (HCC). We evaluated the efficacy and safety of CIK cell therapy in a real-world clinical setting.

METHODS

A retrospective analysis was conducted on 49 patients who received CIK cell therapy after curative resection or radiofrequency ablation, compared with 49 matched control patients via 1:1 propensity score matching. The primary endpoint was recurrence-free survival (RFS), and the secondary endpoint was overall survival (OS).

RESULTS

The median follow-up durations were 19.1 months for the immune cell group and 67.7 months for the control group. In univariable analysis, the immune cell group demonstrated a prolonged RFS than the control group (hazard ratio [HR], 0.32; 95% CI, 0.15-0.71; log-rank p = 0.001). The median RFS was not reached in the immune cell group but was 48.62 months in the control group. A multivariable Cox regression model identified CIK cell therapy as a significant factor associated with a reduced risk of HCC recurrence (adjusted HR, 0.32; 95% CI, 0.15-0.71; p = 0.005). The median OS was not reached in either group; no significant differences in OS were observed between the immune cell and control groups (log-rank p = 0.082). The overall incidence of adverse events was low, and no Grade 3 or 4 events were reported.

CONCLUSIONS

Adjuvant CIK cell immunotherapy after curative treatment significantly prolongs RFS in early-stage HCC patients. Further research regarding the broader applications of CIK cell immunotherapy in HCC is warranted.

Treatment Options for Hepatocellular Carcinoma Using Immunotherapy: Present and Future

Hepatocellular carcinoma (HCC) is a common cancer, and the body's immune responses greatly affect its progression and the prognosis of patients. Immunological suppression and the maintenance of self-tolerance in the tumor microenvironment are essential responses, and these form part of the theoretical foundations of immunotherapy. In this review, we first discuss the tumor microenvironment of HCC, describe immunosuppression in HCC, and review the major biomarkers used to track HCC progression and response to treatment. We then examine antibody-based therapies, with a focus on immune checkpoint inhibitors (ICIs), monoclonal antibodies that target key proteins in the immune response (programmed cell death protein 1, anti-cytotoxic T-lymphocyte associated protein 4, and programmed death-ligand 1) which have transformed the treatment of HCC and other cancers. ICIs may be used alone or in conjunction with various targeted therapies for patients with advanced HCC who are receiving first-line treatments or subsequent treatments. We also discuss the use of different cellular immunotherapies, including T cell receptor (TCR) T cell therapy and chimeric antigen receptor (CAR) T cell therapy. We then review the use of HCC vaccines, adjuvant immunotherapy, and oncolytic virotherapy, and describe the goals of future research in the development of treatments for HCC.

How can Cytokine-induced killer cells overcome CAR-T cell limits

The successful treatment of patients affected by B-cell malignancies with Chimeric Antigen Receptor (CAR)-T cells represented a breakthrough in the field of adoptive cell therapy (ACT). However, CAR-T therapy is not an option for every patient, and several needs remain unmet. In particular, the production of CAR-T cells is expensive, labor-intensive and logistically challenging; additionally, the toxicities deriving from CAR-T cells infusion, such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), have been documented extensively. Alternative cellular therapy products such as Cytokine-induced killer (CIK) cells have the potential to overcome some of these obstacles. CIK cells are a heterogeneous population of polyclonal CD3+CD56+ T cells with phenotypic and functional properties of NK cells. CIK cell cytotoxicity is exerted in a major histocompatibility complex (MHC)-unrestricted manner through the engagement of natural killer group 2 member D (NKG2D) molecules, against a wide range of hematological and solid tumors without the need for prior antigen exposure or priming. The foremost potential of CIK cells lies in the very limited ability to induce graft-versus-host disease (GvHD) reactions in the allogeneic setting. CIK cells are produced with a simple and extremely efficient expansion protocol, which leads to a massive expansion of effector cells and requires a lower financial commitment compared to CAR-T cells. Indeed, CAR-T manufacturing involves the engineering with expensive GMP-grade viral vectors in centralized manufacturing facilities, whereas CIK cell production is successfully performed in local academic GMP facilities, and CIK cell treatment is now licensed in many countries. Moreover, the toxicities observed for CAR-T cells are not present in CIK cell-treated patients, thus further reducing the costs associated with hospitalization and post-infusion monitoring of patients, and ultimately encouraging the delivery of cell therapies in the outpatient setting. This review aims to give an overview of the limitations of CAR-T cell therapy and outline how the use of CIK cells could overcome such drawbacks thanks to their unique features. We highlight the undeniable advantages of using CIK cells as a therapeutic product, underlying the opportunity for further research on the topic.

Novel Cellular Therapies for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer related death worldwide. Most patients present with advanced disease, and current gold-standard management using tyrosine kinase inhibitors or immune checkpoint inhibitors (ICIs) offers modest clinical benefit. Cellular immune therapies targeting HCC are currently being tested in the laboratory and in clinical trials. Here, we review the landscape of cellular immunotherapy for HCC, defining antigenic targets, outlining the range of cell therapy products being applied in HCC (such as CAR-T and TCR-T), and exploring how advanced engineering solutions may further enhance this therapeutic approach.

PD-L1 expression is a predictive biomarker for CIK cell-based immunotherapy in postoperative patients with breast cancer

Background

A sequential combination of radiochemotherapy/endocrinotherapy and cytokine-induced killer cell (CIK) infusion has been shown to be an effective therapy for post-mastectomy breast cancer based on statistical analysis of the patient population. However, whether an individual could obtain an improved prognosis from CIK cell-based treatment remains unknown. In the present study, we focused on immune microenvironment regulation and specifically investigated the relationship between PD-L1 expression and survival benefit from CIK immunotherapy in breast cancer.

Methods

A total of 310 postoperative breast cancer patients who received comprehensive treatment were enrolled in this retrospective study, including 160 patients in the control group (received chemotherapy/radiotherapy/endocrinotherapy) and 150 patients in the CIK cell treatment group (received chemotherapy/radiotherapy/ endocrinotherapy and subsequent CIK infusion).

Results

We found that overall survival (OS) and recurrence-free survival (RFS) were significantly better in the CIK group than that in the control group. PD-L1 expression in tumor tissue sections was showed to be an independent prognostic factor for patients in the CIK treatment group using multivariate survival analysis. Further survival analysis in the CIK group showed that patients with PD-L1 tumor expression exhibited longer OS and RFS. In addition, among all patients who were enrolled in this study, only the patients with PD-L1 expression experienced survival benefits from CIK treatment.

Conclusions

Our study showed the relationship between PD-L1 expression and CIK therapy and revealed that PD-L1 expression in the tumor is as an indicator of adjuvant CIK therapy for postoperative breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0696-8) contains supplementary material, which is available to authorized users.

Adjuvant cytokine-induced killer cell immunotherapy for hepatocellular carcinoma: a propensity score-matched analysis of real-world data

BACKGROUND

Several randomized controlled trials have shown that adjuvant immunotherapy with autologous cytokine-induced killer (CIK) cells prolongs recurrence-free survival (RFS) after curative treatment for hepatocellular carcinoma (HCC). We investigated the efficacy of adjuvant immunotherapy with activated CIK cells in real-world clinical practice.

METHODS

A total of 59 patients who had undergone curative surgical resection or radiofrequency ablation for stage I or II HCC, and subsequently received adjuvant CIK cell immunotherapy at two large-volume centers in Korea were retrospectively included. Propensity score matching with a 1:1 ratio was conducted to avoid possible bias, and 59 pairs of matched control subjects were also generated. The primary endpoint was RFS and the secondary endpoints were overall survival and safety.

RESULTS

The median follow-up duration was 28.0 months (interquartile range, 22.9-42.3 months). In a univariable analysis, the immunotherapy group showed significantly longer RFS than the control group (hazard ratio [HR], 0.42; 95% CI, 0.22-0.80; log-rank P = 0.006). The median RFS in the control group was 29.8 months, and the immunotherapy group did not reach a median RFS. A multivariable Cox proportional hazard analysis showed that immunotherapy was an independent predictor for HCC recurrence (adjusted HR, 0.38; 95% CI, 0.20-0.73; P = 0.004). The overall incidence of adverse events in the immunotherapy group was 16/59 (27.1%) and no patient experienced a grade 3 or 4 adverse event.

CONCLUSIONS

The adjuvant immunotherapy with autologous CIK cells after curative treatment safely prolonged the RFS of HCC patients in a real-world setting.

Cord blood-derived cytokine-induced killer cells combined with blinatumomab as a therapeutic strategy for CD19+ tumors

BACKGROUND

Cytokine-induced killer cells (CIKs) are an advanced therapeutic medicinal product (ATMP) that has shown therapeutic activity in clinical trials but needs optimization. We developed a novel strategy using CIKs from banked cryopreserved cord blood units (CBUs) combined with bispecific antibody (BsAb) blinatumomab to treat CD19⁺ malignancies.

METHODS

CB-CIKs were expanded in vitro and fully characterized in comparison with peripheral blood (PB)-derived CIKs.

RESULTS

CB-CIKs, like PB-CIKs, were mostly CD3⁺ T cells with mean 45% CD3⁺CD56⁺ and expressing mostly TCR(T cell receptor)αβ with a TH1 phenotype. CB-CIK cultures had, however, a larger proportion of CD4⁺ cells, mostly CD56^-, as well as a greater proportion of naïve CCR7⁺CD45RA⁺ and a lower percentage of effector memory cells, compared with PB-CIKs. CB-CIKs were very similar to PB-CIKs in their expression of a large panel of co-stimulatory and inhibitory/exhaustion markers, except for higher CD28 expression among CD8⁺ cells. Like PB-CIKs, CB-CIKs were highly cytotoxic in vitro against natural killer (NK) cell targets and efficiently lysed CD19⁺ tumor cells in the presence of blinatumomab, with 30-60% lysis of target cells at very low effector:target ratios. Finally, both CB-CIKs and PB-CIKs, combined with blinatumomab, showed significant therapeutic activity in an aggressive PDX Ph⁺ CD19⁺ acute lymphoblastic leukemia model in NOD-SCID mice, without sign of toxicity or graft-versus-host disease. The improved expansion protocol was finally validated in good manufacturing practice conditions, showing reproducible expansion of CIKs from cryopreserved cord blood units with a median of 28.8 × 10⁶ CIK/kg.

DISCUSSION

We conclude that CB-CIKs, combined with bispecific T-cell-engaging antibodies, offer a novel, effective treatment strategy for leukemia.

Novel TLR7 agonist stimulates activity of CIK/NK immunological effector cells to enhance antitumor cytotoxicity

Toll-like receptor (TLR) 7/8 agonists have been applied in combination with chemo-, radio- or immunotherapy for lymphoma, and used as topical drugs for the treatment of viral skin lesions and skin tumors. In the present study, the role of an adenine analog, 9-(4-carboxyphenyl)-8-hydroxy-2-(2-methoxyethoxy)-adenine [termed Gao Dong (GD)], a novel TLR7 agonist, in the activation of cytokine-induced killer/natural killer (CIK/NK) cells was determined. The results of the present study indicated that GD was able to activate CIK/NK cells. The proportion of GD-induced CD3⁺CD56⁺ CIK and CD3^-CD56⁺ NK cells was ~4% higher respectively compared with the control. Notably, combination therapy with CIK/NK cells stimulated by GD, markedly suppressed the proliferation of the chronic myelogenous leukemia K562 cell line. Following GD treatment, the cytotoxicity improved by ~25 and 21% when the effector/target ratio was 20:1 and 10:1, respectively. The results of the present study suggested a novel protocol for CIK/NK cell proliferation and revealed that GD may serve as a potent innate and adaptive immunomodulator in immunocyte culture.

Innovative Clinical Perspectives for CIK Cells in Cancer Patients

Cytokine-induced killer (CIK) cells are T lymphocytes that have acquired, in vitro, following extensive manipulation by Interferon gamma (IFN-γ), OKT3 and Interleukin 2 (IL-2) addition, the expression of several Natural Killer (NK) cell-surface markers. CIK cells have a dual "nature", due to the presence of functional TCR as well as NK molecules, even if the antitumoral activity can be traced back only to the NK-like structures (DNAM-1, NKG2D, NKp30 and CD56). In addition to antineoplastic activity in vitro and in several in-vivo models, CIK cells show very limited, if any, GvHD toxicity as well as a strong intratumoral homing. For all such reasons, CIK cells have been proposed and tested in many clinical trials in cancer patients both in autologous and allogeneic combinations, up to haploidentical mismatching. Indeed, genetic modification of CIK cells as well as the possibility of combining them with specific monoclonal antibodies will further expand the possibility of their clinical utilization.

Cellular Immunotherapy for Hematologic Malignancies: Beyond Bone Marrow Transplantation

Immunotherapy has changed treatment practices for many hematologic malignancies. Even in the current era of targeted therapy, chemotherapy remains the backbone of treatment for many hematologic malignancies, especially in acute leukemias, where relapse remains the major cause of mortality. Application of novel immunotherapies in hematology attempts to harness the killing power of the immune system against leukemia and lymphoma. Cellular immunotherapy is evolving rapidly for high-risk hematologic disorders. Recent advances include chimeric antigen-receptor T cells, mesenchymal stromal/stem cells, dendritic cell tumor vaccines, cytokine-induced killer cells, and virus-specific T cells. The advantages of nontransplantation cellular immunotherapy include suitability for patients for whom transplantation has failed or is contraindicated, and a potentially less-toxic treatment alternative to transplantation for relapsed/refractory patients. This review examines those emerging cellular immunotherapies that are changing treatment paradigms for patients with hematologic malignancies.

Anticancer cellular immunotherapies derived from umbilical cord blood

INTRODUCTION

The lack of highly effective drugs in many malignancies has prompted scientific interest in the development of alternative treatment strategies. Cellular immunotherapy involving the adoptive transfer of immune cells that potently recognize and eliminate malignantly transformed cells has become a promising new tool in the anticancer armory. Studies suggest that the unique biological properties of umbilical cord blood (UCB) cells could precipitate enhanced anticancer activity; hence, UCB could be an optimal source for immunotherapy with the potential to provide products with 'off-the-shelf' availability.

AREAS COVERED

In this review, the authors summarize data on the transfer of naturally occurring or genetically modified UCB cells to treat cancer. The focus within is on the phenotypic and functional differences compared to other sources, the alloreactive and anticancer properties, and manufacturing of these products. Therapies utilizing cytokine-induced killer (CIK) cells, natural killer (NK) cells and chimeric antigen receptor (CAR) T-cells, are discussed.

EXPERT OPINION

The cellular immunotherapy field has become a growing, exciting area that has generated much enthusiasm. There is evidence that anticancer immunotherapy with UCB-derived products is feasible and safe; however, considering the limited number of clinical trials using UCB-derived products, further studies are warranted to facilitate translation into clinical practice.

Efficacy of cytokine-induced killer cell infusion as an adjuvant immunotherapy for hepatocellular carcinoma: a systematic review and meta-analysis

This study was designed to evaluate the efficacy and safety of cytokine-induced killer (CIK) cell-based immunotherapy as an adjuvant therapy for hepatocellular carcinoma (HCC). Published studies were identified by searching Medline, Cochrane, EMBASE, and Google Scholar databases with the keywords: cytokine-induced killer cell, hepatocellular carcinoma, and immunotherapy. The outcomes of interest were overall survival, progression-free survival, and disease-free survival. Eight randomized controlled trials (RCTs), six prospective studies, and three retrospective studies were included. The overall analysis revealed that patients in the CIK cell-treatment group had a higher survival rate (pooled hazard ratio (HR) =0.594, 95% confidence interval [CI] =0.501–0.703, P<0.001). Patients treated with CIK cells in non-RCTs had a higher progression-free survival rate (pooled HR =0.613, 95% CI =0.510–0.738, P<0.001). However, CIK cell-treated patients in RCTs had progression-free survival rates similar to those of the control group (pooled HR =0.700, 95% CI =0.452–1.084, P=0.110). The comparison between pooled results of RCTs and non-RCTs regarding the progression-free survival rate did not reach statistical significance. Patients in the CIK cell-treatment group had lower rates of relapse in RCTs (pooled HR =0.635, 95% CI =0.514–0.784, P<0.001). Similar results were found when non-RCT and RCTs were pooled (pooled HR =0.623, 95% CI =0.516–0.752, P<0.001). Adjuvant CIK cell-based immunotherapy is a promising therapeutic approach that can improve overall survival and reduce recurrence in patients with HCC.

Dendritic cells infected by Ad-sh-SOCS1 enhance cytokine-induced killer (CIK) cell immunotherapeutic efficacy in cervical cancer models

BACKGROUND AIMS

Cervical cancer constitutes a major problem in women's health worldwide, but the efficacy of the standard therapy is unsatisfactory. Cytokine-induced killer (CIK) cells exhibit antitumor activity against a variety of malignancies in preclinical models and have proven safe and effective in clinical trials. However, current CIK therapy has limitations and needs to be improved to meet the clinical requirements. The aim of this study was to investigate whether suppressing the expression of cytokine signaling 1 (SOCS1) in dendritic cells (DCs) can shorten in vitro CIK culture time and improve its antitumor efficacy.

METHODS

DCs were pre-cultured for 3 days before infected with adenovirus-mediated-SOCS1 short hairpin RNA (Ad-sh-SOCS1) and pulsed with CTL epitope peptides E7. The DCs infected by Ad-sh-SOCS1 (gmDCs) and CIKs were then co-cultured for 5 or 9 days, and CIK proliferation and antitumor activity were evaluated both in vitro and in vivo.

RESULTS

Our data show that gmDCs significantly stimulated the expansion of co-cultured CIKs and increased the secretion of interferon-γ and interleukin-12. Moreover, gmDCs-activated CIKs showed higher cytotoxic activity against TC-1 cells expressing HPV16E6 and E7. Our in vivo study showed that the mice infused with gmDCs-activated CIKs on day 10 had an increased survival rate and prolonged survival time compared with the controls.

CONCLUSIONS

Taken together, these results indicate that DCs modified by adenovirus-mediated SOCS1 silencing can promote CIKs expansion and enhance the efficacy of antitumor immunotherapy both in vitro and in vivo, which represents an effective therapeutic approach for cervical cancer and other tumors.

Immune checkpoint inhibitors enhance cytotoxicity of cytokine-induced killer cells against human myeloid leukaemic blasts

We studied whether blockade of inhibitory receptors on cytokine-induced killer (CIK) cells by immune checkpoint inhibitors could increase its anti-tumour potency against haematological malignancies. CIK cultures were generated from seven normal donors and nine patients with acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL) or multiple myeloma (MM). The inhibitory receptors B and T lymphocyte attenuator, CD200 receptor, lymphocyte activation gene-3 (LAG-3) and T cell immunoglobulin and mucin-domain-containing-3 (TIM-3) were present at variable percentages in most CIK cultures, while cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed death-1 (PD-1) and killer cell immunoglobulin-like receptors (KIR2DL1/2/3) were expressed at low level in most cultures. Without blockade, myeloid leukaemia cells were susceptible to autologous and allogeneic CIK-mediated cytotoxicity. Blockade of KIR, LAG-3, PD-1 and TIM-3 but not CTLA-4 resulted in remarkable increase in killing against these targets, even in those with poor baseline cytotoxicity. ALL and MM targets were resistant to CIK-mediated cytotoxicity, and blockade of receptors did not increase cytotoxicity to a meaningful extent. Combination of inhibitors against two receptors did not further increase cytotoxicity. Interestingly, potentiation of CIK killing by blocking antibodies was not predicted by expression of receptors on CIK and their respective ligands on the targets. Compared to un-activated T and NK cells, blockade potentiated the cytotoxicity of CIK cells to a greater degree and at a lower E:T ratio, but without significant increase in cytotoxicity against normal white cell. Our findings provide the basis for clinical trial combining autologous CIK cells with checkpoint inhibitors for patients with AML.

Immunotherapy for hepatocellular carcinoma: From basic research to clinical use

Hepatocellular carcinoma (HCC) is a common cancer worldwide with a poor prognosis. Few strategies have been proven efficient in HCC treatment, particularly for those patients not indicated for curative resection or transplantation. Immunotherapy has been developed for decades for cancer control and is attaining more attention as a result of encouraging outcomes of new strategies such as chimeric antigen receptor T cells and immune checkpoint blockade. Right at the front of the new era of immunotherapy, we review the immunotherapy in HCC treatment, from basic research to clinical trials, covering anything from immunomodulators, tumor vaccines and adoptive immunotherapy. The mechanisms, efficacy and safety as well as the approach particulars are unveiled to assist readers to gain a concise but extensive understanding of immunotherapy of HCC.

Adoptive Cell Therapy of Melanoma with Cytokine-induced Killer Cells

Melanoma is the most aggressive skin cancer and its incidence is gradually increasing worldwide. Patients with metastatic melanoma have a very poor prognosis (estimated 5-year survival rate of <16%). In the last few years, several drugs have been approved for malignant melanoma, such as tyrosine kinase inhibitors and immune checkpoint blockades. Although new therapeutic agents have improved progression-free and overall survival, their use is limited by drug resistance and drug-related toxicity. At the same time, adoptive cell therapy of metastatic melanoma with tumor-infiltrating lymphocytes has shown promising results in preclinical and clinical studies. In this review, we summarize the currently available drugs for treatment of malignant melanoma. In addition, we suggest cytokine-induced killer (CIK) cells as another candidate approach for adoptive cell therapy of melanoma. Our preclinical study and several previous studies have shown that CIK cells have potent anti-tumor activity against melanomas in vitro and in an in vivo human tumor xenograft model without any toxicity.

A nomogram for predicting the benefit of adjuvant cytokine-induced killer cell immunotherapy in patients with hepatocellular carcinoma

The benefits of adjuvant cytokine-induced killer (CIK) cell immunotherapy for hepatocellular carcinoma (HCC) remain mixed among patients. Here, we constructed a prognostic nomogram to enable individualized predictions of survival benefit of adjuvant CIK cell treatment for HCC patients. Survival analysis showed that the median overall survival (OS) and progression-free survival (PFS) for patients in the hepatectomy/CIK combination group were 41 and 16 months, respectively, compared to 28 and 12 months for patients in the hepatectomy alone group (control). Based on multivariate analysis of the entire cohort, independent factors for OS were tumor size, tumor capsule, pathological grades, total bilirubin, albumin, prothrombin time, alpha-fetoprotein, and tumor number, which were incorporated into the nomogram. The survival prediction model performed well, as assessed by the c-index and calibration curve. Internal validation revealed a c-index of 0.698, which was significantly greater than the c-index value of the TNM (tumor–node–metastasis) staging systems of 0.634. The calibration curves fitted well. In conclusions, our developed nomogram resulted in more accurate individualized predictions of the survival benefit from adjuvant CIK cell treatment after hepatectomy. The model may provide valuable information to aid in the decision making regarding the application of adjuvant CIK cell immunotherapy.

Anti-CD20 antibody induces the improvement of cytokine-induced killer cell activity via the STAT and MAPK/ERK signaling pathways

There is a current requirement for novel therapeutic strategies for the treatment of hematopoietic tumors. Residual tumor cells are the main origin of tumor relapse. The aim of this study was to eliminate the residual tumor cells of hematopoietic tumors. Cytokine-induced killer (CIK) cells are used in immunotherapy to deplete the residual cells. However, it is necessary to increase the antitumor activity and clinical applicability of CIK cells. The present study investigated the antitumor activity of CIK cells to the SU-DHL2 human B-cell lymphoma and K562 human chronic myelogenous leukemia cell lines. CD3⁺CD56⁺ cells from healthy donors were expanded in culture with cytokines and anti-CD20 monoclonal antibody (mAb; rituximab) to generate CIK cells. A preliminary investigation of their mechanism was then performed. The increase in the cytotoxicity of the CIK cells induced by the anti-CD20 mAb was associated with an increase in the expression of cytotoxic factors. The expression of components of the signal transducer and activator of transcription (STAT) and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathways was found to increase. Upregulation of the expression of STAT1, STAT3 and STAT5 is important as these co-stimulatory molecules enhance T-cell proliferation. Activation of the MAPK signaling pathway is a possible mechanism for the anti-apoptosis effect on the proliferation of CIK cells. In conclusion, anti-CD20 mAb may play an important role in the improvement of CIK-mediated cytotoxicity to tumor cells. These observations may aid in the improvement of the effects of immunotherapy in depleting the residual cells of hematopoietic tumors. Thus, the use of CIK cells cultured with anti-CD20 mAb could be a novel therapeutic strategy for the depletion of chemotherapy-resistant or residual cells in anaplastic large and B-cell lymphoma.

A truncated human NKG2D splice isoform negatively regulates NKG2D-mediated function

Natural killer group 2, member D (NKG2D) is a stimulatory receptor expressed by NK cells and a subset of T cells. NKG2D is crucial in diverse aspects of innate and adaptive immune functions. In this study, we characterize a novel splice variant of human NKG2D that encodes a truncated receptor lacking the ligand-binding ectodomain. This truncated NKG2D (NKG2D(TR)) isoform was detected in primary human NK and CD8(+) T cells. Overexpression of NKG2D(TR) severely attenuated cell killing and IFN-γ release mediated by full-length NKG2D (NKG2D(FL)). In contrast, specific knockdown of endogenously expressed NKG2D(TR) enhanced NKG2D-mediated cytotoxicity, suggesting that NKG2D(TR) is a negative regulator of NKG2D(FL). Biochemical studies demonstrated that NKG2D(TR) was bound to DNAX-activated protein of 10 kDa (DAP10) and interfered with the interaction of DAP10 with NKG2D(FL). In addition, NKG2D(TR) associated with NKG2D(FL), which led to forced intracellular retention, resulting in decreased surface NKG2D expression. Taken together, these data suggest that competitive interference of NKG2D/DAP10 complexes by NKG2D(TR) constitutes a novel mechanism for regulation of NKG2D-mediated function in human CD8(+) T cells and NK cells.

Clinical activity of adjuvant cytokine-induced killer cell immunotherapy in patients with post-mastectomy triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) is a high risk form of this disease, even after surgery, due to the absence of targets for hormone treatment and anti-Her-2 therapy. Chemotherapy is the main therapeutic strategy for such patients with breast cancer, although the outcome is often unsatisfactory. Thus, the development of combination adjuvant therapies is essential for improved prognosis in patients with TNBC. In this study, we investigated the efficacy of a sequential combination of cytokine-induced killer cell (CIK) infusion and chemotherapy for patients with post-mastectomy TNBC.

EXPERIMENTAL DESIGN

From 2008 to 2012, 90 patients with post-mastectomy TNBC were included in this retrospective study: 45 cases received chemotherapy alone or with sequential radiotherapy; a further 45 cases received chemotherapy with/without radiotherapy and sequential CIK infusion.

RESULTS

Survival analysis showed significantly higher disease-free survival (DFS) and overall survival (OS) rates in the CIK treatment group compared with the control group (P = 0.0382, P = 0.0046, respectively; log-rank test). Multivariate survival analysis showed that CIK adjuvant treatment was an independent prognostic factor for OS of patients with TNBC. In subgroup analyses, CIK adjuvant treatment significantly increased the DFS rate of patients with pathologic grade 3, and significantly increased the OS rate of patients in N1, N2, N3, IIB, III TNM (tumor-node-metastasis) stages, and with pathologic grade 3.

CONCLUSIONS

These data indicate that adjuvant CIK treatment combined with chemotherapy is an effective therapeutic strategy to prevent disease recurrence and prolong survival of patients with TNBC, particularly those with lymph node metastasis, advanced TNM stage, and poor pathologic grade. Clin Cancer Res; 20(11); 3003-11. ©2014 AACR.

The efficacy of cytokine-induced killer cell infusion as an adjuvant therapy for postoperative hepatocellular carcinoma patients

BACKGROUND

Even after surgery, hepatocellular carcinoma (HCC) has poor prognosis; adjuvant therapy is needed to improve effectively the outcome of HCC patients. We evaluated the efficacy of cytokine-induced killer (CIK) cell infusion as an adjuvant therapy for postoperative HCC patients.

METHODS

A total of 410 patients were studied retrospectively (January 2002 to January 2007): 206 received surgery alone; 204 received surgery and at least four cycles of CIK cell transfusion (CIK group). Kaplan-Meier and Cox regression analyses were used to explore differences in OS between two groups.

RESULTS

The CIK group overall survival rates were significantly higher than that of the surgery-alone group (log-rank test; p = 0.0007). Multivariate survival analysis showed that CIK cell treatment was an independent prognostic factor. In subgroup analysis, patients who received ≥8 cycles of CIK cell transfusion exhibited significantly better survival than the <8 cycle group (p = 0.0272). There was no significant difference in overall survival in patients with ≤5-cm tumors between the CIK and surgery-alone groups (p = 0.7567). However, in patients with >5-cm tumors, the CIK group displayed significantly better overall survival than the surgery-alone group (p = 0.0002).

CONCLUSIONS

Postoperative immunotherapy with CIK cell transfusion may be an effective adjuvant treatment for improving the outcomes of HCC patients; >8 cycles of CIK cell transfusion may ensure that patients derive maximal benefits. Moreover, patients with large tumors might benefit more from CIK cell adjuvant treatment than patients with small tumors.

Cytokine-induced killer cells co-cultured with complete tumor antigen-loaded dendritic cells, have enhanced selective cytotoxicity on carboplatin-resistant retinoblastoma cells

Retinoblastoma (RB) is a challenging disease that affects mostly young children. Chemical therapy has been shown to have limitations during clinical practice, principally because of the ability of RB to become resistant to the treatment. Nevertheless, chemotherapy is still the main treatment for RB, and immunotherapy has become a promising treatment for most solid tumors with fewer side effects than traditional therapies. In this study, we explored the antitumor effects of cytokine-induced killer (CIK) cells co-cultured with dendritic cells (DCs) pulsed with complete tumor antigens (DC-Ag). Cytotoxicity and specificity were evaluated on an RB cell line (RB-Y79), on a human normal retina cell line (hTERT-RPE1) and a carboplatin-resistant RB cell line. Our results showed that CIK differentiation and cytotoxicity were enhanced by co-culturing CIKs with DC-Ag. Moreover, the co-culture improved the CIK proliferation rate by increasing IL-6 and decreasing IL-10 levels in the culture medium. Furthermore, the use of DC-Ag-CIK cells had little effect on normal retinal cells but high cytotoxicity on RB cells even on carboplatin-resistant retinoblastoma cells. This is the first study showing that DC cells pulsed with the complete tumor antigen improve proliferation, differentiation and cytotoxic activity of CIKs specific not only for RB but also for the chemotherapy-resistant form of the malady. Thus highly efficient immunotherapy based on DC-Ag-CIK cells may be a potential effective and safe mean of treating RB especially to patients where traditional chemical therapy has failed.

Inhibition of human pancreatic tumor growth by cytokine-induced killer cells in nude mouse xenograft model

Pancreatic cancer is the fourth commonest cause of cancer-related deaths in the world. However, no adequate therapy for pancreatic cancer has yet been found. In this study, the antitumor activity of cytokine-induced killer (CIK) cells against the human pancreatic cancer was evaluated in vitro and in vivo. Human peripheral blood mononuclear cells were cultured with IL-2-containing medium in anti-CD3 for 14 days. The resulting populations of CIK cells comprised 94% CD3⁺, 4% CD3^-CD56⁺, 41% CD3⁺CD56⁺, 11% CD4⁺, and 73% CD8⁺. This heterogeneous cell population was called cytokine-induced killer (CIK) cells. At an effector-target cell ratio of 100:1, CIK cells destroyed 51% of AsPC-1 human pancreatic cancer cells, as measured by the ⁵¹Cr-release assay. In addition, CIK cells at doses of 3 and 10 million cells per mouse inhibited 42% and 70% of AsPC-1 tumor growth in nude mouse xenograft assays, respectively. This study suggests that CIK cells may be used as an adoptive immunotherapy for pancreatic cancer patients.

CIK cells from recurrent or refractory AML patients can be efficiently expanded in vitro and used for reduction of leukemic blasts in vivo

Autologous cytokine-induced killer (CIK) cell transfusion may prevent tumor relapse in acute myeloid leukemia (AML). This study investigated whether CIK cells from recurrent or refractory AML patients with high peripheral leukemia cell burdens could be expanded to a clinically usable number, and it further evaluated the antitumor potentials in vitro and in vivo. The numbers and phenotypes of CIK cells expanded from nine AML patients and 10 healthy donors were compared. Cytotoxicity (against K562 and U937 cell lines) and cytokine secretion (interleukin-2, interferon-γ, tumor necrosis factor-α and vascular endothelial growth factor) were tested for AML-derived and healthy donor-derived CIK cells and fresh peripheral blood mononuclear cells from healthy donors. Importantly, we assessed the therapeutic effects of autologous CIK cell infusions in two patients with AML. The proportions of CD3(+)and CD3(+)CD56(+) CIK cells from patients with AML were similar to those from healthy donors, and the number of CD3(+)CD56(+) cells in AML-derived CIK cells was expanded approximately 1,020-fold. Phenotype analyses with flow cytometry showed that the leukemic cells were gradually eliminated during the process of CIK cell preparation to an almost undetectable level. Although the cytotoxic effect of AML-derived CIK cells was equivalent to that of healthy donors, AML-derived CIK cells had a significantly higher cytokine-secreting capacity. In clinical treatment, the leukemia burden in the peripheral blood of one patient was dramatically decreased after four transfusions within 4 months. CIK cells can be efficiently expanded in vitro from patients with recurrent or refractory AML and may be used for reduction of leukemic blasts in vivo.

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.

Cytotoxic Capacity of IL-15-Stimulated Cytokine-Induced Killer Cells Against Human Acute Myeloid Leukemia and Rhabdomyosarcoma in Humanized Preclinical Mouse Models

Allogeneic stem cell transplantation (allo-SCT) has become an important treatment modality for patients with high-risk acute myeloid leukemia (AML) and is also under investigation for soft tissue sarcomas. The therapeutic success is still limited by minimal residual disease (MRD) status ultimately leading to patients' relapse. Adoptive donor lymphocyte infusions based on MRD status using IL-15-expanded cytokine-induced killer (CIK) cells may prevent relapse without causing graft-versus-host-disease (GvHD). To generate preclinical data we developed mouse models to study anti-leukemic- and anti-tumor-potential of CIK cells in vivo. Immunodeficient mice (NOD/SCID/IL-2Rγc(-), NSG) were injected intravenously with human leukemic cell lines THP-1, SH-2 and with human rhabdomyosarcoma (RMS) cell lines RH41 and RH30 at minimal doses required for leukemia or tumor engraftment. Mice transplanted with THP-1 or RH41 cells were randomly assigned for analysis of CIK cell treatment. Organs of mice were analyzed by flow cytometry as well as quantitative polymerase chain reaction for engraftment of malignant cells and CIK cells. Potential of CIK cells to induce GvHD was determined by histological analysis. Tissues of the highest degree of THP-1 cell expansion included bone marrow followed by liver, lung, spleen, peripheral blood (PB), and brain. RH30 and RH41 engraftment mainly took place in liver and lung, but was also detectable in spleen and PB. In spite of delayed CIK cell expansion compared with malignant cells, CIK cells injected at equal amounts were sufficient for significant reduction of RH41 cells, whereas against fast-expanding THP-1 cells 250 times more CIK than THP-1 cells were needed to achieve comparable results. Our preclinical in vivo mouse models showed a reliable 100% engraftment of malignant cells which is essential for analysis of anti-cancer therapy. Furthermore our data demonstrated that IL-15-activated CIK cells have potent cytotoxic capacity against AML and RMS cells without causing GvHD.

Immunomodulation of inducible co-stimulator (ICOS) in human cytokine-induced killer cells against cholangiocarcinoma through ICOS/ICOS ligand interaction

OBJECTIVE

To evaluate the immunomodulation of inducible co-stimulator (ICOS) in cytokine-induced killer (CIK) cells against cholangiocarcinoma.

METHODS

CIK cells were generated from normal peripheral blood mononuclear cells. Methyl thiazolyl tetrazolium assay was performed to assess proliferation of CIK-ICOS and controlled CIK cells; ELISA was used to analyze the expression of cytokines. Reverse transcription-polymerase chain reaction and immunohistochemistry were performed to evaluate the expression of ICOS ligand (ICOSL) in CIK cells and human cholangiocarcinoma cell line QBC939 cells. The cytotoxicity of CIK cells was determined either by lactate dehydrogenase-releasing assay in vivo or alteration of tumor size prior to and after the treatment of CIK cells in vivo.

RESULTS

CIK-ICOS cells proliferated more and expressed higher secretion a level of interferon-γ than the controlled CIK. These cells exhibited higher cytotoxicity against cholangiocarcinoma cell lines at all efficacy: toxicity (E:T) ratios tested than the controlled CIK cells. More importantly, the anti-ICOSL antibody was able to attenuate the elevated cytotoxicity mediated by ICOS overexpression. When injected into cholangiocarcinoma xenografts in severe combined immunodeficiency mice, CIK-ICOS cells survived better than the controlled CIK cells around xenografts and significantly reduced the growth rate of cholangiocarcinoma, with least volume increase and more severe necrosis of the xenografts than controlled mice treated with saline, CIK or CIK-enhanced green fluorescent protein.

CONCLUSION

ICOS can enhance the cytotoxic effect of CIK cells against cholangiocarcinoma both in vitro and in vivo. This effect is mediated by ICOS-augmented cytokine secretion and cell proliferation, and in part through ICOS-ICOSL interaction.

Anti-leukemia effect of ex vivo expanded DNT cells from AML patients: a potential novel autologous T-cell adoptive immunotherapy

CD3(+)CD56(-), CD4 and CD8 double negative T (DNT) cells comprise 1-3% of peripheral blood (PB) mononuclear cells. Their role in tumor immunity remains largely unknown due to their limited numbers and lack of effective methods to expand them. Here we developed a novel protocol by which DNT cells can be expanded ex vivo to therapeutic levels in 2 weeks from 13 of 16 acute myeloid leukemia (AML) patients during chemotherapy-induced complete remission. The expanded DNT cells expressed similar or higher levels of interferon-γ and tumor necrosis factor-α and Granzyme B as that seen in bulk activated CD8T cells from the same patient but significantly higher levels of perforin. The expanded DNT cells could effectively kill both allogeneic and autologous primary CD34(+) leukemic blasts isolated from PB of AML patients in a perforin-dependant manner. These results demonstrate, for the first time, that DNT cells from AML patients can be expanded ex vivo even after intensive chemotherapy, and are effective at killing both allogeneic and autologous primary leukemic blasts. These findings warrant studies further exploring the potential of DNT cells as a novel adjuvant immunotherapy to decrease the risk of relapse in patients with AML and, perhaps, other cancers.

Clinical scale expansion of cytokine-induced killer cells is feasible from healthy donors and patients with acute and chronic myeloid leukemia at various stages of therapy

OBJECTIVE

In our clinical studies involving cytokine-induced killer (CIK) cells for patients with hematological malignancies, starting cells came from a heterogeneous group of patients and donors. Here we study the feasibility of expansion and analyzed the characteristics of the end product from starting cells derived from different sources and at different disease states.

MATERIALS AND METHODS

Seventy-five clinical scale cultures were grown from 28 patients and 20 donors in Good Manufacturing Practices facilities under CIK condition.

RESULTS

CIK cells could be successfully expanded from healthy donors, patients with acute myeloid leukemia recovering from chemotherapy, untreated patients with acute myeloid leukemia or myelodysplastic syndrome with circulating leukemic blasts, and patients with chronic myeloid leukemia on imatinib. Furthermore, CIK cells of donor origin could be expanded from leukapheresis product collected from patients who relapsed post-allogeneic transplantation, thereby offering a useful method of obtaining activated donor cells in patients for whom further donor cells were unavailable. Interestingly, CIK cells cultured from patients with untreated acute myeloid leukemia and myelodysplastic syndrome had a significantly higher proportion of CD3(+)CD56(+) subset and higher fold expansion of CD3(+) cells as compared to other groups of patients or healthy donors. Multivariate analysis showed that fresh starting cells expanded better than frozen-thawed cells, while prior exposure to granulocyte colony-stimulating factor or imatinib before harvesting did not adversely affect CIK cell expansion.

CONCLUSIONS

Clinical scale expansion of CIK cells is feasible from both healthy donors and leukemia patients at various stages of treatment. This robust system allows clinical translation using CIK cells as immunotherapy in various clinical settings.

A clinical study of cytokine-induced killer cells for the treatment of refractory lymphoma

Cytokine-induced killer (CIK) cell therapy, an adoptive T-cell immunotherapy, has been reported to be a safe and effective mode of treatment for patients with metastatic diseases, lymphoma and acute leukaemia. To investigate the clinical efficacy of cytokine-induced killer cells for the treatment of refractory lymphoma, the present clinical study was conducted. A total of 8 male patients with a mean age of 41 years (range 22-65) who were pathologically diagnosed with malignant lymphoma (Hodgkin's disease, 2 and non-Hodgkin's lymphoma, 6) were enrolled. CIK cells were expanded by priming with IFN-γ, monoclonal antibody (mAb) to CD3 and IL-1α, followed by the addition of IL-2 the following day using peripheral blood mononuclear cells (PBMCs) of the 8 male patients. The CIK cells were then transfused back to the patients as treatment. On day 13, the CIK cell count reached 7-18×10(19) (mean, 12.7×10(9)), a 44- to 140-fold increase (mean, 98-fold). The average percentage of cells expressing CD3(+), CD4(+), CD8(+) and CD3(+)CD56(+) were also increased from 50.9±3.5, 29.9±1.7, 41.3±3.2, 1.6±0.2% to 90.2±1.6, 40.6±5.5, 52.8±4.9 and 33.1±4.0%, respectively. Patients showed measurable radiographic tumor reduction, increased T-cell subset levels, and relief of symptoms after treatment. No severe toxicity or side effects were reported. CIK cells developed by this culture method have a high in vitro proliferation rate and tumor-killing capacity. In conclusion, CIK cell treatment of patients with malignant lymphoma achieves effective clinical responses, causing few side effects.

Enhanced killing of human B-cell lymphoma targets by combined use of cytokine-induced killer cell (CIK) cultures and anti-CD20 antibodies

We have investigated combining adoptive immunotherapy with cytokine-induced killer (CIK) cells and anti-CD20 monoclonal antibodies (mAb) GA101 or rituximab to optimize B-cell non-Hodgkin lymphoma (B-NHL) therapy. CIK cultures alone demonstrated significant cytotoxic activity against B-NHL cell lines or freshly isolated samples in either an autologous or allogeneic combination. This natural cytotoxicity (NC) was mainly due to the predominating CD3(+)CD56(+) CIK population (40%-75%) present in the cultures. The addition of anti-CD20 mAb GA101 or rituximab further increased cytotoxicity by 35% and 15%, respectively. This enhancement was mainly due to antibody-dependent cytotoxicity (ADCC) mediated by the 1%-10% NK cells contaminating CIK cultures. The addition of human serum (HS) inhibited NK-cell activation induced by rituximab, but not activation induced by GA101.Overall lysis in presence of serum, even of a resistant B-NHL cell line, was significantly increased by 100 μg/mL of rituximab, but even more so by GA101, with respect to CIK cultures alone. This was due to the combined action of complement-mediated cytotoxicity (CDC), ADCC, and CIK-mediated NC. These data suggest that rituximab, and even more so GA101, could be used in vivo to enhance CIK therapeutic activity in B-NHL.

IL-12 enhances efficacy and shortens enrichment time in cytokine-induced killer cell immunotherapy

Cytokine-induced killer (CIK) cells are T cell derived ex vivo expanded cells with both NK and T cell properties. They exhibit potent anti-tumor efficacy against various malignancies in preclinical models and have proven safe and effective in clinical studies. We combined CIK cell adoptive immunotherapy with IL-12 cytokine immunotherapy in an immunocompetent preclinical breast cancer model. Combining CIK cells with IL-12 increased anti-tumor efficacy in vivo compared to either therapy alone. Combination led to full tumor remission and long-term protection in 75% of animals. IL-12 treatment sharply increased the anti-tumor efficacy of short-term cultured CIK cells that exhibited no therapeutic effect alone. Bioluminescence imaging based in vitro cytotoxicity and in vivo homing assays revealed that short-term cultured CIK cells exhibit full cytotoxicity in vitro, but display different tumor homing properties than fully expanded CIK cells in vivo. Our data suggest that short-term cultured CIK cells can be "educated" in vivo, producing fully expanded CIK cells upon IL-12 administration with anti-tumor efficacy in a mouse model. Our findings demonstrate the potential to improve current CIK cell-based immunotherapy by increasing efficacy and shortening ex vivo expansion time. This holds promise for a highly efficacious cancer therapy utilizing synergistic effects of cytokine and cellular immunotherapy.

Efficient lysis of rhabdomyosarcoma cells by cytokine-induced killer cells: implications for adoptive immunotherapy after allogeneic stem cell transplantation

BACKGROUND

Rhabdomyosarcoma is the most common soft tissue sarcoma in childhood and has a poor prognosis. Here we assessed the capability of ex vivo expanded cytokine-induced killer cells to lyse both alveolar and embryonic rhabdomyosarcoma cell lines and investigated the mechanisms involved.

DESIGN AND METHODS

Peripheral blood mononuclear cells from six healthy donors were used to generate and expand cytokine-induced killer cells. The phenotype and composition of these cells were determined by multiparameter flow cytometry, while their cytotoxic effect against rhabdomyosarcoma cells was evaluated by a europium release assay.

RESULTS

Cytokine-induced killer cells efficiently lysed cells from both rhabdomyosarcoma cell lines. Antibody-mediated masking of either NKG2D molecule on cytokine-induced killer cells or its ligands on rhabdomyosarcoma cells (major histocompatibility antigen related chain A and B and UL16 binding protein 2) diminished this effect by 50%, suggesting a major role for the NKG2D molecule in rhabdomyosarcoma cell killing. No effect was observed after blocking CD11a, CD3 or TCRalphabeta molecules on cytokine-induced killer cells or CD1d on rhabdomyosar-coma cells. Remarkably, cytokine-induced killer cells used tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to activate caspase-3, as the main caspase responsible for the execution of apoptosis. Accordingly, blocking TRAIL receptors on embryonic rhabdomyosarcoma cell lines significantly reduced the anti-tumor effect of cytokine-induced killer cells. About 50% of T cells within the cytokine-induced killer population had an effector memory phenotype, 20% had a naïve phenotype and approximately 30% of the cells had a central memory phenotype. In addition, cytokine-induced killer cells expressed low levels of activation-induced markers CD69 and CD137 and demonstrated a low alloreactive potential.

CONCLUSIONS

Our data suggest that cytokine-induced killer cells may be used as a novel adoptive immunotherapy for the treatment of patients with rhabdomyosarcoma after allogeneic stem cell transplantation.

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

Cytokine-induced killer (CIK) cells are polyclonal T effector cells generated when cultured under cytokine stimulation. CIK cells exhibit potent, non-MHC-restricted cytolytic activities against susceptible tumor cells of both autologous and allogeneic origins. Over the past 20 years, CIK cells have evolved from experimental observations into early clinical studies with encouraging preliminary efficacy towards susceptible autologous and allogeneic tumor cells in both therapeutic and adjuvant settings. This paper is our attempt to summarize the available published literature related to CIK cells. Looking into the future, we anticipate that the continuous therapeutic application of CIK cells will likely be developed along two major directions: overcoming the challenge to organize large prospective randomized clinical trials to define the roles of CIK cells in cancer immunotherapy and expanding its spectrum of cytotoxicity towards resistant tumor cells through experimental manipulations.

Correlation of peripheral blood Vα24 NK T cell count with the severity of hepatic injury in patients with chronic hepatitis B virus infection

AIM: To investigate the changes in the number of Vα24 natural killer (NK) T cells in peripheral blood and its possible correlation with the severity of hepatic injury in patients with chronic hepatitis B virus (HBV) infection.

METHODS: Twenty-six patients with chronic hepatitis B (CHB), 9 patients with liver cirrhosis (LC), 8 patients with acute-on-chronic liver failure (ACLF), and 7 normal controls (NCs) were included in the study. The percentage of Vα24 NK T cells in total peripheral blood T lymphocytes was determined by flow cytometry.

RESULTS: The percentages of Vα24 NKT cells in patients with CHB and ACLF were significantly lower than that in NCs (0.8012% ± 0.2979% and 0.4638% ± 0.2244% vs 1.1114% ± 0.3546%, respectively, both P < 0.05). The percentage of Vα24 NK T cells had a significant positive correlation with prothrombin time (PT) and a significant negative correlation with total bilirubin (TB), but had no significant correlations with serum alanine aminotransferase (ALT) and HBV DNA level.

CONCLUSION: The percentage of Vα24 NK T cells in peripheral blood decreases with the aggravation of hepatic injury in patients with chronic HBV infection, implying that Vα24 NKT cells play an important role in the pathogenesis of chronic hepatitis B.

Immunotherapy with cytokine induced killer cells in solid and hematopoietic tumours: a pilot clinical trial

BACKGROUND AND OBJECTIVES

CIK cells are a novel population of efficient immune effector cells with high antitumour activity mainly due to the high proliferation of CD3(+)CD56(+) cells, so may play a role in the development of new forms of adoptive cellular immunotherapy. We started a pilot clinical trial with autologous CIK cells in patients with refractory lymphoma and metastatic solid tumours. This study was aimed at determining the feasibility of generating a sufficient number of CIK cells in heavily pretreated patients and at assessing treatment toxicity.

DESIGN AND METHODS

CIK cells were generated from peripheral blood mononuclear cells (MNC) and incubated in the presence of IFN-gamma followed by OKT3 and IL-2. Treatment schedule consisted of three cycles of CIK cells infusions at an interval of 3 weeks.

RESULTS

At present 12 patients were enrolled: 6 advanced lymphomas, 5 metastatic kidney carcinoma and 1 hepatocellular carcinoma (HCC). The median number of transferred cells per patient was 28 x 10(9) (range, 6-61). Protocol adherence was excellent and the toxicity profile was favourable. After CIK cells infusion, the absolute median count of lymphocytes, CD3(+), CD8(+) and CD3(+)CD56(+) cells significantly increased in patient's peripheral blood. Clinical outcome appeared promising: three patients had complete response (CR) and two patients had stabilization of disease with a median follow-up of 33 months (range, 9-44).

INTERPRETATIONS AND CONCLUSIONS

These preliminary data showed that adoptive immunotherapy with CIK cells is a safe therapy with some suggestion of efficacy that significantly enhances immune functions increasing absolute numbers of effector cells without side effects. If confirmed in larger scale studies, these promising results may have a favourable impact on conventional treatment strategy of malignancies.

Cytokine induced killer cells as adoptive immunotherapy strategy to augment graft versus tumor after hematopoietic cell transplantation

Donor lymphocyte infusion (DLI) is used to increase the graft versus tumor (GVT) effect after allogeneic hematopoietic cell transplant (HCT). The limited spectrum of activity and high risk of graft versus host disease (GVHD) remain major limitations of this approach. The finding of new cell populations for adoptive immunotherapy, with the ability to separate GVT from GVHD, would be useful. Here we review the main basic, preclinical and clinical research on cytokine-induced killer (CIK) cells, highlighting the aspects of their antitumor and alloreactive potentials that might favourably affect the balance between GVT and GVHD. CIK cells are ex vivo-expanded T lymphocytes sharing NK markers and endowed with a potent MHC-unrestricted antitumor activity against haematological and solid malignancies. Studies in preclinical animal models have demonstrated their low GVHD potential when infused across MHC-barriers, and recent clinical studies seem to confirm these findings in patients with hematological malignancies relapsing after HCT. If consolidated with larger clinical trials, adoptive immunotherapy with CIK cells might represent an effective alternative to classic DLI, helping HCT to succesfully meet current challenges like the extension across major HLA-barriers and application to solid tumors.

Antitumor activity of cytokine-induced killer cells in nude mouse xenograft model

Malignant glioma is the most common primary brain tumor in adults and the median survival for patients is less than a year. Despite aggressive treatments including surgical resection, radiotherapy, and chemotherapy, only modest improvement has been achieved in the survival of patients with glioma. In this study, the antitumor activity of cytokine-induced killer (CIK) cells against human glioma cancer was evaluated in vitro and in vivo. Human peripheral blood mononuclear cells were cultured with IL-2-containing medium in anti-CD3 antibody-coated flasks for 5 days, followed by incubation in IL-2-containing medium for 9 days. The number of cells increased more than 200-fold and the viability was >90%. The resulting populations were consisted of 96% CD3(+), 2% CD3(-)CD56(+), 68% CD3(+)CD56(+), 2% CD4(+), <1% CD4(+)CD56(+), 80% CD8(+), and 49% CD8(+)CD56(+). This heterogeneous cell population was called as CIK cells. At an effector-target cell ratio of 30:1, CIK cells destroyed 43% of U-87 MG human glioma cells, as measured by the (51)Cr-release assay. In addition, CIK cells at doses of 0.3, 1, and 3 million cells per mouse inhibited 23%, 40%, and 50% of U-87 MG tumor growth in nude mouse xenograft assays, respectively. This study suggests that CIK cells may be used as an adoptive immunotherapy for glioma cancer patients.

Cytokine-induced killer cells are terminally differentiated activated CD8 cytotoxic T-EMRA lymphocytes

OBJECTIVE

Cytokine-induced killer cells (CIK) are CD3(+)CD56(+) T cells with natural killer (NK)-like cytotoxic activity used for the immunotherapy of tumors. We aimed to fully characterize CIK cells and define their ontogeny.

MATERIALS AND METHODS

CIK were generated in vitro by stimulation of peripheral blood mononuclear cells or T-cell subsets with interferon-gamma, anti-CD3 and interleukin-2. They were fully characterized in terms of phenotype, cytotoxic activity, and gene expression with respect to circulating CD3(+)CD56(+) cells, NK cells, and CD56(-) T cells present in CIK cultures.

RESULTS

We demonstrate that CIK are terminally differentiated CD8 T cells that derive from proliferating CD3(+)CD56(-)CD8(+) T cells. They express polyclonal T-cell receptor Vbeta chains and have acquired CD56, NKG2D, and large granular lymphocyte morphology, but lack expression of most NK-specific activating (NKp30, NKp44, NKp46) and inhibitory (KIR2DL1, KIR2DL2, KIR3DL1, NKG2A, CD94) receptors, and can kill K562 targets. Circulating CD3(+)CD56(+) cells are also CD8(+)CD16(-), but are oligoclonal, poorly cytotoxic for K562, and express lower levels of CD56 and NKG2D. Gene profiling of CIK, CD56(-) T and NK cells present at the end of culture shows that differences are much more limited between CIK and CD56(-) T compared to CIK and NK cells. Most of the genes upregulated in CIK cells compared to CD56(-) T cells are part of the tumor necrosis factor gene network.

CONCLUSIONS

The CIK phenotype, that is CD45RA(+), CCR7(-), CD62L-weakly positive, CD11a(+), CD27(+), CD28(-), macrophage inflammatory protein 1alpha(+), perforin(+), Fas ligand(+) coincides almost exactly with that described for the T RA(+) effector memory CD27 single positive subset of terminally differentiated human memory T cells.

Inducible costimulator (ICOS) enhances the cytolytic activity of cytokine-induced killer cells against gallbladder cancer in vitro and in vivo

The generation of genetically modified immunological effector cells is of potential therapeutic value in the treatment of malignancies. Cytokine-induced killer cells (CIKs) have been described as highly efficient cytotoxic effector cells capable of recognizing and lysing tumor cell targets in a non-major histocompatibility complex restricted fashion. In the present study, we evaluated the effects of inducible costimulator (ICOS) on the cytotoxicity of CIK cells against gallbladder cancer. We first prepared CIK-ICOS cells by the transfection of ICOS genes into induced CIK cells, whereas untransfected or enhanced green fluorescent protein (EGFP)-transfected CIK cells were treated as controls. We found that CIK-ICOS cells displayed better proliferation and lower apoptosis than the other two CIK control cells after culture. The interferon-gamma level in the culture supernatant of CIK-ICOS cells was also significantly elevated, compared to CIK or CIK-EGFP cells. The cytotoxic effect of CIK-ICOS cells against gallbladder cancer cells was dramatically enhanced at the E:T ratio of 20:1, compared to that of CIK or CIK-EGFP cells. When injected into gallbladder tumor-bearing SCID mice, CIK-ICOS cells significantly slowed down the growth rate of xenografts. CIK-ICOS-treated mice exhibited the least volume variation of the xenografts and more severe necrosis, compared to saline, CIK, or CIK-EGFP cell-treated mice, accompanied by a better in situ survival around xenografts than the other two control cells. Taken together, our results demonstrated that ICOS could enhance the cytotoxic activity of CIK cells, in part, by augmenting cytokine secretion and prolonging cell survival both in vitro and in vivo. This might be considered as the potential immunomodulator for clinical therapy.

In vivo trafficking and survival of cytokine-induced killer cells resulting in minimal GVHD with retention of antitumor activity

Cytokine-induced killer (CIK) cells are ex vivo-expanded T lymphocytes expressing both natural killer (NK)- and T-cell markers. CIK cells are cytotoxic against autologous and allogeneic tumors. We previously showed that adoptive transfer of allogeneic CIK cells in a murine model caused minimal graft-versus-host disease (GVHD). However, the precise mechanism of reduced GVHD is not fully understood. Therefore, we evaluated the trafficking and survival of luciferase-expressing CIK cells in an allogeneic bone marrow transplant model. The initial trafficking patterns of CIK cells were similar to conventional T cells that induced GVHD; however, CIK cells infiltrated GVHD target tissues much less and transiently. CIK cells accumulated and persisted in tumor sites, resulting in tumor eradication. We evaluated different properties of CIK cells compared with conventional T cells, demonstrating a slower division rate of CIK cells, higher susceptibility to apoptosis, persistent increased expression of interferon gamma (IFN-gamma), and reduced acquisition of homing molecules required for entry of cells into inflamed GVHD target organs that lack expression of NKG2D ligands recognized by CIK cells. Due to these properties, allogeneic CIK cells had reduced expansion and caused less tissue damage. We conclude that CIK cells have the potential to separate graft-versus-tumor effects from GVHD.

Characterization of the recognition and functional heterogeneity exhibited by cytokine-induced killer cell subsets against acute myeloid leukaemia target cell

The polyclonal cytokine-induced killer (CIK) cells exhibit potent cytotoxicity against a variety of tumour cells including autologous and allogeneic acute myeloid leukaemic (AML) targets. At maturity, three lymphocyte subsets: CD3(-) CD56(+), CD3(+) CD56(-) and CD3(+) CD56(+), constitute the bulk of the CIK cell culture. The CD3(-) CD56(+) subset behaves like classical natural killer (NK) cells where cytotoxicity is potentiated by blocking the human leucocyte antigen Class I molecules in the AML targets. Both the CD3(+) CD56(+) and CD3(+) CD56(-) subsets, though known to kill autologous and allogeneic targets to a comparable degree and therefore non-major histocompatibility complex (MHC)-restricted, nevertheless require the presence of the MHC molecule on the target, which interacts with their CD3-T-cell receptor complex. Although CIK cells are often termed 'NK-like' T cells, we have demonstrated that the well-characterized NK receptors KIR, NKG2C/E, NKG2D and DNAM-1 are not involved in the process of AML recognition for the CD3(+) CD56(-) and CD3(+) CD56(+) subsets. The CD3(+) CD56(+) and CD3(+) CD56(-) subsets express a polyclonal and comparable TCRVbeta repertoire in a Gaussian distribution. The CD3(+) CD56(+) subset kills AML targets more efficiently than its CD3(+) CD56(-) counterpart because of the presence of a higher proportion of CD8(+) cells. The CD3(+) CD56(+) subset comprise more terminally differentiated late effector T cells that bear the CD27(+) CD28(-) or CD27(-) CD28(-) phenotype, with a higher granzyme A content. In comparison, the phenotype of the CD3(+) CD56(-) subset is consistent with early effector T cells that are CD27(+) CD28(+) and CD62L(+), known to be less cytotoxic but possess greater proliferative potential.

Anti-tumor activity of ex vivo expanded cytokine-induced killer cells against human hepatocellular carcinoma

Cytokine-induced killer (CIK) cells are ex vivo expanded T cells with natural killer cell phenotypes and functions. In this study, the anti-tumor activity of CIK cells against hepatocellular carcinoma was evaluated in vitro and in vivo. In the presence of anti-CD3 antibody and IL-2 for 14 days, human peripheral blood mononuclear cell population changed to heterogeneous CIK cell population, which comprised 96% CD3(+), 3% CD3( inverted exclamation mark(c))CD56(+), 32% CD3(+)CD56(+), 11% CD4(+), 75% CD8(+), and 30% CD8(+)CD56(+). CIK cells produced significant amounts of IFN-gamma and TNF-alpha; however, produced only slight amounts of IL-2, IL-4, and IL-5. At an effector-target cell ratio of 30:1, CIK cells destroyed 33% of SNU-354 human hepatocellular carcinoma cells, which was determined by the (51)Cr-release assay. In addition, a dose of 1x10(6) CIK cells per mouse inhibited 60% of SNU-354 tumor growth in irradiated nude mice. This study suggests that CIK cells may be used as an adoptive immunotherapy for patients with hepatocellular carcinoma.