Cytokine-induced killer cells targeted by the novel bispecific antibody CD19xCD5 (HD37xT5.16) efficiently lyse B-lymphoma cells

Profiling targets and potential target pairs of CAR-T cell therapy in clinical trials

Since the approval of the first chimeric antigen receptor (CAR)-T product in 2017, the number of new CAR-T clinical trials worldwide exceeds 100 per year. 1649 clinical studies have been conducted to explore possible future clinical applications of targets or target pairs through different biotechnologies. In this study, we aim to take a data-driven analytical approach to explore potential dual-target pairs based on clinical trial information. We screened 1283 non-withdrawal interventional CAR-T clinical trials spanning 96 different targets and 74 target pairs from clinicaltrials.gov. Through the Circos plot and temporal network plots, the information between targets and indications was visualized. Based on the assumption that two targets of a target pair must target the same indication, five new target pairs were inferred, including CD19/CD7, CD19/CD5, CD19/CD37, and CD19/BAFFR and validated by expression pattern, literature and patent information. This study provides novel support for target profiling of CAR-T from the perspective of clinical trials and also provides a reference for researchers and developers to select new targets or target pairs of CAR-T cell therapy.

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.

Clinical Studies on Cytokine-Induced Killer Cells: Lessons from Lymphoma Trials

Simple Summary

Lymphoma is a heterogeneous group of neoplasms including over 70 different subtypes. Its biological characteristic of deriving from lymphoid tissues makes it ideal for immunotherapy. In this paper, we provide insights into lymphoma-specific clinical trials based on cytokine-induced killer (CIK) cell therapy. We also reviewed pre-clinical lymphoma models where CIK cells have been used along with other synergetic tumor-targeting immune modules to improve their therapeutic potential. From a broader perspective, we will highlight that CIK cell therapy has potential, and in this rapidly evolving landscape of cancer therapies its optimization (as a personalized therapeutic approach) will be beneficial in lymphomas.

Abstract

Cancer is a complex disease where resistance to therapies and relapses often pose a serious clinical challenge. The scenario is even more complicated when the cancer type itself is heterogeneous in nature, e.g., lymphoma, a cancer of the lymphocytes which constitutes more than 70 different subtypes. Indeed, the treatment options continue to expand in lymphomas. Herein, we provide insights into lymphoma-specific clinical trials based on cytokine-induced killer (CIK) cell therapy and other pre-clinical lymphoma models where CIK cells have been used along with other synergetic tumor-targeting immune modules to improve their therapeutic potential. From a broader perspective, we will highlight that CIK cell therapy has potential, and in this rapidly evolving landscape of cancer therapies its optimization (as a personalized therapeutic approach) will be beneficial in lymphomas.

Recent advances in cellular therapy for malignant lymphoma

Cellular therapies for malignant lymphoma include autologous or allogeneic hematopoietic stem cell transplantation (HSCT) and adaptive cellular therapy using EBV-specific T cells, cytokine-induced killer (CIK) cells, NKT cells, NK cells, chimeric antigen receptor T (CAR-T) cells and chimeric antigen receptor NK (CAR-NK) cells. In this review we discusses recent advances of these cellular therapies and consider ways to optimize these therapies. Not only a single strategy using one of these cellular therapies, but also multi-disciplinary treatment combines with antibodies, such as an anti-tumor antibody and an immune checkpoint antibody, may be more effective for relapsed and refractory lymphoma.

Current Immunotherapy Approaches in Non-Hodgkin Lymphomas

Non-Hodgkin lymphomas (NHLs) are lymphoid malignancies of B- or T-cell origin. Despite great advances in treatment options and significant improvement of survival parameters, a large part of NHL patients either present with a chemotherapy-refractory disease or experience lymphoma relapse. Chemotherapy-based salvage therapy of relapsed/refractory NHL is, however, capable of re-inducing long-term remissions only in a minority of patients. Immunotherapy-based approaches, including bispecific antibodies, immune checkpoint inhibitors and genetically engineered T-cells carrying chimeric antigen receptors, single-agent or in combination with therapeutic monoclonal antibodies, immunomodulatory agents, chemotherapy or targeted agents demonstrated unprecedented clinical activity in heavily-pretreated patients with NHL, including chemotherapy-refractory cases with complex karyotype changes and other adverse prognostic factors. In this review, we recapitulate currently used immunotherapy modalities in NHL and discuss future perspectives of combinatorial immunotherapy strategies, including patient-tailored approaches.

Ten-year update of the international registry on cytokine-induced killer cells in cancer immunotherapy

Cytokine-induced killer (CIK) cells represent an exceptional T-cell population uniting a T cell and natural killer cell-like phenotype in their terminally differentiated CD3⁺ CD56⁺ subset, which features non-MHC-restricted tumor-killing activity. CIK cells have provided encouraging results in initial clinical studies and revealed synergistic antitumor effects when combined with standard therapeutic procedures. We established the international registry on CIK cells (IRCC) to collect and evaluate clinical trials for the treatment of cancer patients in 2010. Moreover, our registry set new standards on the reporting of results from clinical trials using CIK cells. In the present update, a total of 106 clinical trials including 10,225 patients were enrolled in IRCC, of which 4,889 patients in over 30 distinct tumor entities were treated with CIK cells alone or in combination with conventional or novel therapies. Significantly improved median progression-free survival and overall survival were shown in 27 trials, and 9 trials reported a significantly increased 5-year survival rate. Mild adverse effects and graft-versus-host diseases were also observed in the studies. Recently, more efforts have been put into the improvement of antitumoral efficacy by CIK cells including the administration of immune checkpoint inhibitors and modification with chimeric antigen receptorc. The minimal toxicity and multiple improvements on their tumor-killing activity both make CIK cells a favorable therapeutic tool in the clinical practice of cancer immunotherapy.

Bispecific, T-Cell-Recruiting Antibodies in B-Cell Malignancies

Bispecific antibodies (BsAbs) are designed to recognize and bind to two different antigens or epitopes. In the last few decades, BsAbs have been developed within the context of cancer therapies and in particular for the treatment of hematologic B-cell malignancies. To date, more than one hundred different BsAb formats exist, including bispecific T-cell engagers (BiTEs), and new constructs are constantly emerging. Advances in protein engineering have enabled the creation of BsAbs with specific mechanisms of action and clinical applications. Moreover, a better understanding of resistance and evasion mechanisms, as well as advances in the protein engineering and in immunology, will help generating a greater variety of BsAbs to treat various cancer types. This review focuses on T-cell-engaging BsAbs and more precisely on the various BsAb formats currently being studied in the context of B-cell malignancies, on ongoing clinical trials and on the clinical concerns to be taken into account in the development of new BsAbs.

Cell transfer-based immunotherapies in cancer: A review

In cell transfer therapy (CTT), immune cells such as innate immune-derived natural killer cells and dendritic cells as well as acquired immune-related T lymphocytes such as tumor-infiltrating lymphocytes and cytokine-activated or genetically modified peripheral blood T cells are used in the management of cancer. These therapies are increasingly becoming the most used treatment modality in cancer after tumor resection, chemotherapy, and radiotherapy. In adoptive cell transfer, the lymphocytes isolated from either a donor or the patient are modified ex vivo and reinfused to target malignant cells. Transferring in vitro-manipulated immune cells produces a continuous antitumor immune response. In this review, we evaluate the recent advances in CTT for the management of various malignancies.

Promising immunotherapy: Highlighting cytokine-induced killer cells

For many years, cancer therapy has appeared to be a challenging issue for researchers and physicians. By the introduction of novel methods in immunotherapy, the prospect of cancer therapy even more explained than before. Cytokine-induced killer (CIK) cell-based immunotherapy demonstrated to have potentiality in improving clinical outcomes and relieving major side effects of standard treatment options. In addition, given the distinctive features such as high safety, low toxicity effects on healthy cells, numerous clinical trials conducted on CIK cells. Due to the shortcomings that observed in CIK cell immunotherapy alone, arising a tendency to make modifications (combined modality therapy or combination therapy) including the addition of various types of cytokines, genetic engineering, combination with immune checkpoints, and so on. In this review, we have tried to bring forth the latest immunotherapy methods and their overview. We have discussed the combination therapies with CIK cells and the conducted clinical trials. This helps the future studies to use integrated therapies with CIK cells as a promising treatment of many types of cancers.

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.

T cell engaging bispecific antibody (T-BsAb): From technology to therapeutics

Harnessing the power of the human immune system to treat cancer is the essence of immunotherapy. Monoclonal antibodies engage the innate immune system to destroy targeted cells. For the last 30years, antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity have been the main mechanisms of anti-tumor action of unconjugated antibody drugs. Efforts to exploit the potentials of other immune cells, in particular T cells, culminated in the recent approval of two T cell engaging bispecific antibody (T-BsAb) drugs, thereby stimulating new efforts to accelerate similar platforms through preclinical and clinical trials. In this review, we have compiled the worldwide effort in exploring T cell engaging bispecific antibodies. Our special emphasis is on the lessons learned, with the hope to derive insights in this fast evolving field with tremendous clinical potential.

Influence of the number and interval of treatment cycles on cytokine-induced killer cells and their adjuvant therapeutic effects in advanced non-small-cell lung cancer (NSCLC)

OBJECTIVE

Cytokine-induced killer (CIK) cells have important therapeutic effects in adoptive cell transfer (ACT) for the treatment of various malignancies. In this study, we focused on in vitro expansion of CIK cells and their clinical efficacy in combination with chemotherapy in patients with advanced non-small-cell lung cancer (NSCLC).

METHODS

A total of 64 patients with NSCLC (enrolled from 2011 to 2012), including 32 patients who received chemotherapy alone or with sequential radiotherapy (conventional treatment, control group) and 32 patients who received conventional treatment and sequential CIK infusion (study group), were retrospectively analyzed. The time to progression (TTP), overall survival (OS) and adverse effects were analyzed and the phenotype of lymphocytes in CIK population was also determined by flow cytometry.

RESULTS

After in vitro expansion, the average percentage of CIK cells was 26.35%. During the 54-month follow up, the median OS and TTP were significantly longer in the study group than in the control group (P=0.0189 and P=0.0129, respectively). The median OS of the ACT≥4cycles subgroup was significantly longer than that of the ACT<4cycles subgroup (P=0.0316). The percentage of CIK cells in patients who received ≥4cycles of ACT was higher than that in patients treated with <4cycles of ACT (P=0.0376). Notably, CIK cells were difficult to expand in vitro in some patients after the first ACT cycle but became much easier as the treatment cycles increased monthly. Longer treatment interval negatively impacted the expansion of CIK cells.

CONCLUSIONS

Systematic immune levels can be increasingly boosted by reinfusion of ACT. Conventional treatment plus CIK cells is an effective therapeutic strategy to prevent progression and prolong survival of patients with advanced NSCLC.

Cytokine-Induced Killer Cells As Pharmacological Tools for Cancer Immunotherapy

Cytokine-induced killer (CIK) cells are a heterogeneous population of effector CD3⁺CD56⁺ natural killer T cells, which can be easily expanded in vitro from peripheral blood mononuclear cells. CIK cells work as pharmacological tools for cancer immunotherapy as they exhibit MHC-unrestricted, safe, and effective antitumor activity. Much effort has been made to improve CIK cells cytotoxicity and treatments of CIK cells combined with other antitumor therapies are applied. This review summarizes some strategies, including the combination of CIK with additional cytokines, dendritic cells, check point inhibitors, antibodies, chemotherapeutic agents, nanomedicines, and engineering CIK cells with a chimeric antigen receptor. Furthermore, we briefly sum up the clinical trials on CIK cells and compare the effect of clinical CIK therapy with other immunotherapies. Finally, further research is needed to clarify the pharmacological mechanism of CIK and provide evidence to formulate uniform culturing criteria for CIK expansion.

Modification of cytokine-induced killer cells with folate receptor alpha (FRα)-specific chimeric antigen receptors enhances their antitumor immunity toward FRα-positive ovarian cancers

Folate receptor alpha (FRα) is aberrantly expressed in ovarian cancers but largely absent in normal tissues, and therefore represents an attractive target for immunotherapy. In recent years, modification of T cells with chimeric antigen receptor (CAR) targeting FRα has been reported to improve antitumor immunity of T cells. However, there are limited data regarding CAR-modified cytokine-induced killer (CAR-CIK) cells. In the present study, we modified CIK cells with FRα-specific CARs and investigated their antitumor immunity against ovarian cancers. We found that both non-transduced and mock CAR-transduced CIK cells showed only low antitumor activity against either FRα-positive (FRα⁺) or FRα-negative (FRα^-) targets. However, all three generations of CAR-modified CIK cells showed enhanced antitumor activity against FRα⁺ targets, but not FRα^- targets. First-generation ζ-CAR-CIK cells increased production of IFN-γ, enhanced short-term cytotoxicity against FRα⁺ ovarian cancer cells, and showed modest and short-term suppression of established tumors; while second-generation 28ζ- and third-generation 28BBζ-CAR-CIK cells showed significant proliferation, enhanced secretion of IL-2, eliminated the FRα⁺ ovarian cancer cells in long-term co-culture, and showed dramatic and long-term inhibition of tumor growth and prolonged survival of xenograft-bearing mice. It is noteworthy that the 28BBζ-CAR was more potent in the modification of CIK cells than 28ζ-CAR both in vitro and in vivo. Moreover, CAR-CIK cells showed more efficient anticancer activity compared with CAR-T cells in vitro, but less efficient than CAR-T cells in vivo. According to these results, we conclude that modification of CIK cells with FRα-specific CARs enhances their antitumor immunity to FRα⁺ ovarian cancers. The third-generation 28BB-ζ CAR containing 4-1BB co-stimulation was more efficient in modification of CIK cells than either first-generation ζ-CAR or second-generation CD28-ζ-CAR.

Cytokine-induced killer cells efficiently kill stem-like cancer cells of nasopharyngeal carcinoma via the NKG2D-ligands recognition

Cancer stem cells (CSCs) are considered to be the root cause for cancer treatment failure. Thus, there remains an urgent need for more potent and safer therapies against CSCs for curing cancer. In this study, the antitumor activity of cytokine-induced killer (CIK) cells against putative CSCs of nasopharyngeal carcinoma (NPC) was fully evaluated in vitro and in vivo. To visualize putative CSCs in vitro by fluorescence imaging, and image and quantify putative CSCs in tumor xenograft-bearing mice by in vivo bioluminescence imaging, NPC cells were engineered with CSC detector vector encoding GFP and luciferase (Luc) under control of Nanog promoter. Our study reported in vitro intense tumor-killing activity of CIK cells against putative CSCs of NPC, as revealed by percentage analysis of side population cells, tumorsphere formation assay and Nanog-promoter-GFP-Luc reporter gene strategy plus time-lapse recording. Additionally, time-lapse imaging firstly illustrated that GFP-labeled or PKH26-labeled putative CSCs or tumorspheres were usually attacked simultaneously by many CIK cells and finally killed by CIK cells, suggesting the necessity of achieving sufficient effector-to-target ratios. We firstly confirmed that NKG2D blockade by anti-NKG2D antibody significantly but partially abrogated CIK cell-mediated cytolysis against putative CSCs. More importantly, intravenous infusion of CIK cells significantly delayed tumor growth in NOD/SCID mice, accompanied by a remarkable reduction in putative CSC number monitored by whole-body bioluminescence imaging. Taken together, our findings suggest that CIK cells demonstrate the intense tumor-killing activity against putative CSCs of NPC, at least in part, by NKG2D-ligands recognition. These results indicate that CIK cell-based therapeutic strategy against CSCs presents a promising and safe approach for cancer treatment.

Recognition and killing of cancer stem-like cell population in hepatocellular carcinoma cells by cytokine-induced killer cells via NKG2d-ligands recognition

There is an urgent need for more potent and safer approaches to eradicate cancer stem cells (CSCs) for curing cancer. In this study, we investigate cancer-killing activity (CKA) of cytokine-induced killer (CIK) cells against CSCs of hepatocellular carcinoma (HCC). To visualize CSCs in vitro by fluorescence imaging, and image and quantify CSCs in tumor xenograft-bearing mice by bioluminescence imaging, HCC cells were engineered with CSC detector vector encoding GFP and luciferase controlled by Nanog promoter. We found that CIK cells have a strong CKA in vitro against putative CSCs of HCC, as shown by tumorsphere formation and time-lapse imaging. Additionally, time-lapse recording firstly revealed that putative CSCs were attacked simultaneously by many CIK cells and finally eradicated by CIK cells, indicating the necessity of achieving sufficient effector-to-target ratios. We firstly illustrated that anti-NKG2D antibody blocking partially but significantly inhibited CKA of CIK cells against putative CSCs. More importantly, intravenous infusion of CIK cells remarkably delayed tumor growth in mice with a significant decrease in putative CSC number monitored by bioluminescence imaging. Taken together, these findings demonstrate CKA of CIK cells against putative CSCs of HCC, at least in part, by NKG2D-ligands recognition.

Adoptive Immunotherapies After Allogeneic Hematopoietic Stem Cell Transplantation in Patients With Hematologic Malignancies

Hematopoietic stem cell transplantation (HSCT) is the only curative therapy for patients with chemotherapy-resistant hematologic malignancies that are usually fatal in absence of treatment. Hematopoietic stem cell transplantation is associated with significant early and late morbidity and mortality. Graft-versus-host disease, infections, and relapse are the most important causes of mortality after HSCT. Until now, these complications have been managed mainly with pharmacological drugs, but in some situations, this approach clearly shows its limit. As such, there is a significant need for novel therapies for the treatment of complications after allogeneic HSCT. In this review, the currently available adoptive immunotherapies offering an alternative in case of treatment failure of HSCT complications will be described. The results of the main clinical trials based on immune cell infusion will be discussed and the strategies aiming at maximizing cytotoxic T-lymphocyte, regulatory T-cell, natural killer cell, cytokine-induced killer cell, and γδ T-cell efficacies in the context of immunotherapy approaches after allogeneic HSCT in patients with hematologic malignancies will be gathered.

A killer choice for cancer immunotherapy

The promise of cell-based immunotherapies for the treatment of cancer offers the potential of therapeutic synergy with chemo- and radiotherapies that may overcome current limitations leading to durable responses and prevention of recurrence. There is a wide array of cell-based immunotherapies that are either poised to enter cancer clinical trials or are in clinical trials, and many are showing some success. Yet within this field, there are clear obstacles that need to be overcome, including limited access across tissue barriers, development of antigen tolerance, and the immunosuppressive microenvironment of tumors. Through an understanding of immune cell signaling and trafficking, immune cell populations can be selected for adoptive transfer, and delivery strategies can be developed that circumvent these obstacles to effectively direct populations of cells with robust anti-tumor efficacy to the target. Within the realm of immune cell therapies, cytokine-induced killer (CIK) cells have demonstrated promising trafficking patterns, effective delivery of synergistic therapeutics, and stand-alone efficacy. Here, we discuss the next generation of CIK therapies and their application for the effective treatment of a wide variety of cancers.

Purified anti-CD3 × anti-HER2 bispecific antibody potentiates cytokine-induced killer cells of poor spontaneous cytotoxicity against breast cancer cells

Background

Chemical crosslinking is the most straightforward method to produce bispecific antibodies (BsAb) for arming ex vivo activated cytotoxic T lymphocytes. However, heterogeneous polymers are produced by chemical crosslinking. Currently, it is not known under what circumstances or to what extent further purification is needed.

Results

In this study, we purified Traut’s Reagent-Sulfo-SMCC crosslinked anti-CD3 × anti-HER2 by size-exclusion column chromatography and compared the capacity of the crude and the purified forms of the BsAb in enhancing cytokine-induced killer (CIK) cell-mediated cytotoxicity in vitro. We found that the purified BsAb assisted CIK cells more efficiently than the crude form only when the spontaneous cytotoxicity of the CIK cells was relatively low; otherwise, the two forms performed almost identically.

Conclusions

For the CIK cells of low spontaneous cytotoxicity, purified BsAb is a more powerful substitute for crude BsAb in enhancing their killing efficacy. However, that purification of BsAb is not necessary for robust CIK cells. This phenomenon also corroborates that CIK-mediated cytotoxicity is highly dependent on cell contact.

Electronic supplementary material

The online version of this article (doi:10.1186/2045-3701-4-70) contains supplementary material, which is available to authorized users.

The experimental study on the treatment of cytokine-induced killer cells combined with EGFR monoclonal antibody against gastric cancer

AIMS

To investigate the antitumor activity of cytokine-induced killer (CIK) cells combined with epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) against gastric cancer cell line SGC7901.

MATERIALS AND METHODS

Immunocytochemistry assay was performed to detect the expression of EGFR in SGC7901 cell lines. The cytotoxicity activity of CIK cells combined with EGFR mAb was analyzed by the (51)Cr release assay. Then, the comparison of the cytotoxicity activity between CIK cells combined with EGFR mAb and CIK cells combined with CD3 mAb and CIK cells was conducted. Antitumor activity of CIK cells combined with EGFR mAb in vivo was analyzed by tumor growth assay and tumor reduction assay.

RESULTS

The cell lysis rate of CIK cells combined with EGFR mAb was higher than those of CIK cells combined with CD3 mAb and CIK cells only (p<0.05). The lysis rates of the latter two groups were not different. The antitumor activity of CIK cells combined with EGFR mAb was higher than those of other groups in vivo (p<0.05).

CONCLUSION

It was suggested in the current study that EGFR mAb could enhance the antitumor ability of CIK cells to bind and kill the gastric cancer cells in vitro and in vivo.

Cell transfer therapy for cancer: past, present, and future

Cell transfer therapy for cancer has made a rapid progress recently and the immunotherapy has been recognized as the fourth anticancer modality after operation, chemotherapy, and radiotherapy. Lymphocytes used for cell transfer therapy include dendritic cells, natural killer (NK) cells, and T lymphocytes such as tumor-infiltrating lymphocytes (TILs) and cytotoxic T lymphocytes (CTLs). In vitro activated or engineered immune cells can traffic to cancer tissues to elicit persistent antitumor immune response which is very important especially after immunosuppressive treatments such as chemotherapy. In this review, we overviewed recent advances in the exploration of dendritic cells, NK cells, and T cells for the treatment of human cancer cells.

Cytokine-induced killer (CIK) cells bound with anti-CD3/anti-CD133 bispecific antibodies target CD133(high) cancer stem cells in vitro and in vivo

CD133 is a common marker of cancer stem cells (CSCs). We generated an anti-CD3/anti-CD133 bispecific antibody (BsAb) and bound it to the cytokine-induced killer (CIK) cells as effector cells (BsAb-CIK) to target CD133(high) CSCs. The killing of CD133(high) pancreatic (SW1990) and hepatic (Hep3B) cancer cells by the BsAb-CIK cells was significantly (p<0.05) higher than the killing by the parental CIK or by CIK cells bound with anti-CD3 (CD3-CIK) without CD133 targeting. In nude mice, the BsAb-CIK cells inhibited CD133(high) tumor growth significantly (p<0.05) more than that by CIK or CD3-CIK cells, or by the BsAb alone. BsAb-CIK cells co-cultured with CD133(high) cells produced significantly (p<0.05) higher amount of IFN-γ. Treatment with the BsAb-CIK cells significantly downregulated the expression of S100P and IL-18bp, but upregulated STAT1. The findings may help with the development of novel immunotherapies for patients with cancer containing CD133(high) CSCs by selectively targeting this cell population.

Cytotoxicity of cytokine-induced killer cells targeted by a bispecific antibody to gastric cancer cells

The aim of the present study was to investigate the cytotoxic activity of cytokine-induced killer (CIK) cells targeted by an epidermal growth factor receptor (EGFR)/CD3 bispecific antibody (BsAb) to the gastric cancer cell line SGC7901. A BsAb was constructed by chemically cross-linking a monoclonal antibody (McAb) against human CD3 with another McAb against human EGFR. An immunocytochemistry assay was performed to detect the expression of EGFR in SGC7901 cells. The cytotoxic activity of CIK cells targeted by the EGFR/CD3 BsAb was analyzed by the ⁵¹Cr release assay, Subsequently, a comparison of the cytotoxic activity between CIK cells targeted by EGFR/CD3 BsAb, CIK cells targeted by EGFR McAb or/and CD3 McAb and CIK cells was performed. The antineoplastic activity of the CIK cells directed using the EGFR/CD3 BsAb in vivo was analyzed by tumor growth and tumor reduction assays. The cell lysis rate of CIK cells targeted by the EGFR/CD3 BsAb was higher compared with those of CIK cells targeted by CD3 McAb only or by CD3 McAb and EGFR McAb. The lysis rates of the latter two groups were significantly higher than those of CIK cells targeted by EGFR McAb only and CIK cells (P<0.05). The mean tumor reduction using the administration of CIK cells directed by the EGFR/CD3 BsAb was higher than those of the other groups (P<0.05). The results indicate that the EGFR/CD3 BsAb is able to enhance the ability of CIK cells to bind to and kill gastric cancer cells in vitro and in vivo.

The anti-tumour activity of allogeneic cytokine-induced killer cells in patients who relapse after allogeneic transplant for haematological malignancies

We performed a Phase I/II clinical trial to study the feasibility, toxicity and efficacy of allogeneic cytokine-induced killer (CIK) cell expansion, and treatment for patients with haematological malignancies who relapsed after allogeneic haemopoietic SCT (allo-HSCT). Allogeneic CIK cells were successfully generated for a total of 24 patients, including those from patients' own leukapheresis products in 5 patients who had no access to further donor cells. The median CD3(+) T-cell expansion was 9.33 (1.3-38.97) fold, and CD3(+)CD56(+) natural killer (NK)-like T-cell expansion was 27.77 (2.59-438.93) fold. A total of 55 infusions were done for 16 patients who had either failed or progressed after initial response to various individualized chemotherapy regimens and donor lymphocyte infusion (DLI), at doses ranging from 10 to 200 million CD3(+) cells/kg. Response attributable to CIK cell infusion was observed in five patients. These included two with ALL, two with Hodgkin's disease (HD) and one with AML, and two of whom had a response sustained for more than 2 years. Acute GVHD occurred in three and was easily treatable. This study provides some evidence suggestive of the efficacy of allogeneic CIK cells even after failure of DLI in some cases.

Cytokine induced killer cells as promising immunotherapy for solid tumors

Cytokine-induced killer (CIK) cells are a heterogeneous subset of ex-vivo expanded T lymphocytes which present a mixed T-NK phenotype and are endowed with a MHC-unrestricted antitumor activity. The main functional properties of CIK cells may address some of the main limitations that are currently preventing the successful clinical translation of adoptive immunotherapy strategies. Clinically adequate quantities of immune effectors, sufficient for multiple adoptive infusions, may be obtained based on their relatively easy and inexpensive ex-vivo expansion starting from peripheral blood mononuclear cells. The MHC-unrestricted tumor-killing is mainly based on the interaction between NKG2D molecules on CIK cells and MIC A/B or ULBPs molecules on tumor cells; it has been proved effective against several solid and hematological malignancies and does not require any HLA-restriction increasing the number of patients that might potentially benefit from such approach. Finally, CIK cells present a reduced alloreactivity across HLA-barriers with important clinical implications for their potential use as alternative to conventional Donor Lymphocyte Infusions after allogeneic hemopoietic cell transplant with a reduced risk of GVHD. In the present report we review the main functional characteristics of CIK cells discussing recent findings and future perspectives to improve their antitumor activity and potential clinical applications.