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

Challenges and solutions for therapeutic TCR-based agents

Recent development of methods to discover and engineer therapeutic T-cell receptors (TCRs) or antibody mimics of TCRs, and to understand their immunology and pharmacology, lag two decades behind therapeutic antibodies. Yet we have every expectation that TCR-based agents will be similarly important contributors to the treatment of a variety of medical conditions, especially cancers. TCR engineered cells, soluble TCRs and their derivatives, TCR-mimic antibodies, and TCR-based CAR T cells promise the possibility of highly specific drugs that can expand the scope of immunologic agents to recognize intracellular targets, including mutated proteins and undruggable transcription factors, not accessible by traditional antibodies. Hurdles exist regarding discovery, specificity, pharmacokinetics, and best modality of use that will need to be overcome before the full potential of TCR-based agents is achieved. HLA restriction may limit each agent to patient subpopulations and off-target reactivities remain important barriers to widespread development and use of these new agents. In this review we discuss the unique opportunities for these new classes of drugs, describe their unique antigenic targets, compare them to traditional antibody therapeutics and CAR T cells, and review the various obstacles that must be overcome before full application of these drugs can be realized.

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.

Retargeting of NK-92 Cells against High-Risk Rhabdomyosarcomas by Means of an ERBB2 (HER2/Neu)-Specific Chimeric Antigen Receptor

The dismal prognosis of pediatric and young adult patients with high-risk rhabdomyosarcoma (RMS) underscores the need for novel treatment options for this patient group. In previous studies, the tumor-associated surface antigen ERBB2 (HER2/neu) was identified as targetable in high-risk RMS. As a proof of concept, in this study, a novel treatment approach against RMS tumors using a genetically modified natural killer (NK)-92 cell line (NK-92/5.28.z) as an off-the-shelf ERBB2-chimeric antigen receptor (CAR)-engineered cell product was preclinically explored. In cytotoxicity assays, NK-92/5.28.z cells specifically recognized and efficiently eliminated RMS cell suspensions, tumor cell monolayers, and 3D tumor spheroids via the ERBB2-CAR even at effector-to-target ratios as low as 1:1. In contrast to unmodified parental NK-92 cells, which failed to lyse RMS cells, NK-92/5.28.z cells proliferated and became further activated through contact with ERBB2-positive tumor cells. Furthermore, high amounts of effector molecules, such as proinflammatory and antitumoral cytokines, were found in cocultures of NK-92/5.28.z cells with tumor cells. Taken together, our data suggest the enormous potential of this approach for improving the immunotherapy of treatment-resistant tumors, revealing the dual role of NK-92/5.28.z cells as CAR-targeted killers and modulators of endogenous adaptive immunity even in the inhibitory tumor microenvironment of high-risk RMS.

Immunotherapy of gastric cancer: Past, future perspective and challenges

Gastric cancer is considered as the third leading cause of deaths and the fifth most common cancers worldwide. Common treatment approaches include chemotherapy, radiation, gastric resection and targeted therapies. The emergence of gastric cancer immunotherapy has already shown some promising results and have altered the therapeutic procedures. Now, different combination therapies as well as novel immunotherapies targeting new molecules have been proposed. Despite ongoing investigations on the therapeutic options and significant advancements in this regard, the disease is poorly prognosed. In fact, limited therapeutic options and delayed diagnosis lead to the progression, dissemination and metastasis of the disease. Current immunotherapies are mostly based on cytotoxic immunocytes, monoclonal antibodies and gene transferred vaccines. The use of Immune checkpoint inhibitors (ICIs) have grown rapidly. In this review, we aimed to explore perspective and progression of different approaches of immunotherapy in the treatment of GC and the clinical outcomes reported so far. We also summarized the tumor immunosurveillance and tumor immunoescape.

Autologous cytokine-induced killer (CIK) cells enhance the clinical response to PD-1 blocking antibodies in patients with advanced non-small cell lung cancer: A preliminary study

Background

Programmed death‐1 (PD‐1) blocking antibodies have been shown to improve progression‐free survival (PFS) and overall survival in a subset of patients with non–small cell lung cancer (NSCLC). However, the objective response rate with these agents remains low, and the vast majority of NSCLC patients require alternative combination treatment regimens to prolong their survival. The purpose of this study was to evaluate the clinical efficacy of autologous cytokine‐induced killer (CIK) cell infusions combined with PD‐1 blocking antibodies in patients with NSCLC.

Methods

In this preliminary study, we investigated the safety and immune function effectiveness of PD‐1 blockade antibodies pembrolizumab or nivolumab administered in combination with or without autologous CIK cell infusions in 18 patients with advanced NSCLC. The peripheral blood mononuclear cells were isolated from these patients and the expression level of some cell surface molecules like PD‐1 were detected using flow cytometry to reflect the effectiveness of this combination regimen.

Results

No treatment‐related deaths occurred in either cohort. In comparison with the pretreatment level, CD3⁺CD56⁺CD16⁺ T cells were significantly increased with the combination therapy, while myeloid‐derived suppressor cells were significantly increased with PD‐1 blocking antibody therapy alone but not with combination therapy. Although the serum interleukin‐4 level was downregulated following treatment with the combination regimen, interferon‐γ levels were unchanged.

Conclusions

The purpose of this clinical study was to report the clinical efficacy and lack of exacerbated autoimmune adverse events with a combination of PD‐1 blockade and CIK cell infusions in patients with advanced NSCLC, further supporting assessments of this combination in future clinical trials.

CSPG4-Specific CAR.CIK Lymphocytes as a Novel Therapy for the Treatment of Multiple Soft-Tissue Sarcoma Histotypes

PURPOSE

No effective therapy is available for unresectable soft-tissue sarcomas (STS). This unmet clinical need prompted us to test whether chondroitin sulfate proteoglycan 4 (CSPG4)-specific chimeric antigen receptor (CAR)-redirected cytokine-induced killer lymphocytes (CAR.CIK) are effective in eliminating tumor cells derived from multiple STS histotypes in vitro and in immunodeficient mice.

EXPERIMENTAL DESIGN

The experimental platform included patient-derived CAR.CIK and cell lines established from multiple STS histotypes. CAR.CIK were transduced with a retroviral vector encoding second-generation CSPG4-specific CAR (CSPG4-CAR) with 4-1BB costimulation. The functional activity of CSPG4-CAR.CIK was explored in vitro, in two- and three-dimensional STS cultures, and in three in vivo STS xenograft models.

RESULTS

CSPG4-CAR.CIK were efficiently generated from patients with STS. CSPG4 was highly expressed in multiple STS histotypes by in silico analysis and on all 16 STS cell lines tested by flow cytometry. CSPG4-CAR.CIK displayed superior in vitro cytolytic activity against multiple STS histotypes as compared with paired unmodified control CIK. CSPG4-CAR.CIK also showed strong antitumor activity against STS spheroids; this effect was associated with tumor recruitment, infiltration, and matrix penetration. CSPG4-CAR.CIK significantly delayed or reversed tumor growth in vivo in three STS xenograft models (leiomyosarcoma, undifferentiated pleomorphic sarcoma, and fibrosarcoma). Tumor growth inhibition persisted for up to 2 weeks following the last administration of CSPG4-CAR.CIK.

CONCLUSIONS

This study has shown that CSPG4-CAR.CIK effectively targets multiple STS histotypes in vitro and in immunodeficient mice. These results provide a strong rationale to translate the novel strategy we have developed into a clinical setting.

The Synergistic Use of IL-15 and IL-21 for the Generation of NK Cells From CD3/CD19-Depleted Grafts Improves Their ex vivo Expansion and Cytotoxic Potential Against Neuroblastoma: Perspective for Optimized Immunotherapy Post Haploidentical Stem Cell Transplantation

Neuroblastoma (NB) is the most common solid extracranial tumor in childhood. Despite therapeutic progress, prognosis in high-risk NB is poor and innovative therapies are urgently needed. Therefore, we addressed the potential cytotoxic capacity of interleukin (IL)-activated natural killer (NK) cells compared to cytokine-induced killer (CIK) cells for the treatment of NB. NK cells were isolated from peripheral blood mononuclear cells (PBMCs) by indirect CD56-enrichment or CD3/CD19-depletion and expanded with different cytokine combinations, such as IL-2, IL-15, and/or IL-21 under feeder-cell free conditions. CIK cells were generated from PBMCs by ex vivo stimulation with interferon-γ, IL-2, OKT-3, and IL-15. Comparative analysis of expansion rate, purity, phenotype and cytotoxicity was performed. CD56-enriched NK cells showed a median expansion rate of 4.3-fold with up to 99% NK cell content. The cell product after CD3/CD19-depletion consisted of a median 43.5% NK cells that expanded significantly faster reaching also 99% of NK cell purity. After 10–12 days of expansion, both NK cell preparations showed a significantly higher median cytotoxic capacity against NB cells relative to CIK cells. Remarkably, these NK cells were also capable of efficiently killing NB spheroidal 3D culture in long-term cytotoxicity assays. Further optimization using a novel NK cell culture medium and a prolonged culturing procedure after CD3/CD19-depletion for up to 15 days enhanced the expansion rate up to 24.4-fold by maintaining the cytotoxic potential. Addition of an IL-21 boost prior to harvesting significantly increased the cytotoxicity. The final cell product consisted for the major part of CD16⁻, NCR-expressing, poly-functional NK cells with regard to cytokine production, CD107a degranulation and antitumor capacity. In summary, our study revealed that NK cells have a significantly higher cytotoxic potential to combat NB than CIK cell products, especially following the synergistic use of IL-15 and IL-21 for NK cell activation. Therefore, the use of IL-15+IL-21 expanded NK cells generated from CD3/CD19-depleted apheresis products seems to be highly promising as an immunotherapy in combination with haploidentical stem cell transplantation (SCT) for high-risk NB patients.

Adoptive cellular immunotherapy for refractory childhood cancers: a single center experience

Prognosis of refractory childhood cancers despite multimodal treatment strategies remains poor. Here, we report a single center experience encountered in 18 patients with refractory solid malignancies treated with adoptive cellular immunotherapy (ACI) from haploidentical or matched donors following hematopoietic stem cell transplantation. While seven patients were in partial and six in complete remission (CR), five patients suffered from relapsed diseases at the time of ACI. 1.5-year probabilities of overall survival (OS) and progression-free survival (PFS) were 19.5% and 16.1% for all patients. Patients in CR showed estimated 1.5-year OS and PFS of 50.1% and 42.7%, respectively. CR was induced or rather sustained in ten children, with two still being alive 9.6 and 9.3 years after ACI. Naïve, central and effector memory T-cells correlated with responses. However, the majority of patients relapsed. Cumulative incidence of relapse was 79.8% at 1.5 years. Acute graft versus host disease (aGVHD) occurred in nine of 18 patients (50%) with aGVHD grade I–II observed in six (33%) and aGVHD grade III seen in three (17%) patients, manageable in all cases.

Altogether, study results indicate that donor-derived ACI at its current state offers palliation but no clear curative benefit for refractory childhood cancers and warrants further improvement.

Improving Clinical Manufacturing of IL-15 Activated Cytokine-Induced Killer (CIK) Cells

Cytokine-induced killer (CIK) cells are an immunotherapeutic approach to combat relapse following allogeneic hematopoietic stem cell transplantation (HSCT) in acute leukemia or myelodysplastic syndrome (MDS) patients. Prompt and sequential administration of escalating cell doses improves the efficacy of CIK cell therapy without exacerbating graft vs. host disease (GVHD). This study addresses manufacturing-related issues and aimed to develop a time-, personal- and cost-saving good manufacturing process (GMP)-compliant protocol for the generation of ready-for-use therapeutic CIK cell doses starting from one unstimulated donor-derived peripheral blood (PB) or leukocytapheresis (LP) products. Culture medium with or without the addition of either AB serum, fresh frozen plasma (FFP) or platelet lysate (PL) was used for culture. Fresh and cryopreserved CIK cells were compared regarding expansion rate, viability, phenotype, and ability to inhibit leukemia growth. Cell numbers increased by a median factor of 10-fold in the presence of FFP, PL, or AB serum, whereas cultivation in FFP/PL-free or AB serum-free medium failed to promote adequate CIK cell proliferation (p < 0.01) needed to provide clinical doses of 1 × 10⁶ T cells/kG, 5 × 10⁶ T cells/kG, 1 × 10⁷ T cells/kG, and 1 × 10⁸ T cells/kG recipient body weight. CIK cells consisting of T cells, T- natural killer (T-NK) cells and a minor fraction of NK cells were not significantly modified by different medium supplements. Moreover, neither cytotoxic potential against leukemic THP-1 cells nor cell activation shown by CD25 expression were significantly influenced. Moreover, overnight and long-term cryopreservation had no significant effect on the composition of CIK cells, their phenotype or cytotoxic potential. A viability of almost 93% (range: 89–96) and 89.3% (range: 84–94) was obtained after freeze-thawing procedure and long-term storage, respectively, whereas viability was 96% (range: 90-97) in fresh CIK cells. Altogether, GMP-complaint CIK cell generation from an unstimulated donor-derived PB or LP products was feasible. Introducing FFP, which is easily accessible, into CIK cell cultures was time- and cost-saving without loss of viability and potency in a 10-12 day batch culture. The feasibility of cryopreservation enabled storage and delivery of sequential highly effective ready-for-use CIK cell doses and therefore reduced the number of manufacturing cycles.

Enhanced metabolic activities for ATP production and elevated metabolic flux via pentose phosphate pathway contribute for better CIK cells expansion

Objective

Ex vivo expansion is an effective way to produce cytokine‐induced killer (CIK) cells needed for clinical trials. Here, ex vivo expansion and metabolism characters of CIK cells in static and dynamic cultures and the relationship between cell expansion and metabolism were investigated.

Materials and methods

Oxygen transfer efficiency was assessed by computational fluid dynamics technique. Cell phenotype, apoptosis and of transporter expression were determined by flow cytometry and Western blotting. Metabolites and enzyme activities were assessed by biochemical methods.

Results

Dynamic cultures favoured better CIK cell expansion without impairing their phenotype and cytotoxicity, enhanced oxygen transfer efficiency. The glucose metabolism flux of cells in dynamic cultures was enhanced by upregulating surface glucose transporter 1 expression and phosphofructokinase activity. Moreover, pentose phosphate pathway (PPP) metabolic flux was enhanced through upregulating glucose‐6‐phosphate dehydrogenase activity. Glutaminolysis was also accelerated via boosting glutamine transporters expression, glutaminase (GLS) and glutamate dehydrogenase activities. Together with higher oxygen consumption rate and extracellular acidification rate, it was suggested that cells in dynamic cultures were in a more vigorous metabolic state for ATP production.

Conclusion

Dynamic cultures accelerated glucose and glutamine metabolic flux to promote ATP production, elevated glucose metabolic flux through PPP to promote biosynthesis for better cell expansion. These findings may provide the basis for ex vivo CIK cell expansion process optimization.

Dynamic suspension culture improves ex vivo expansion of cytokine-induced killer cells by upregulating cell activation and glucose consumption rate

Ex vivo expansion is an effective strategy to acquire cytokine-induced killer (CIK) cells needed for clinical trials. In this work, the effects of dynamic suspension culture, which was carried out by shake flasks on a shaker, on CIK cells were investigated by the analysis of expansion characteristics and physiological functions, with the objective to optimize the culture conditions for ex vivo expansion of CIK cells. The results showed that the expansion folds of total cells in dynamic cultures reached 69.36 ± 30.36 folds on day 14, which were significantly higher than those in static cultures (9.24 ± 1.12 folds, P < 0.05), however, the proportions of CD3⁺ cells and CD3⁺CD56⁺ cells in both cultures were similar, leading to much higher expansion of CD3⁺ cells and CD3⁺CD56⁺ cells in dynamic cultures. Additionally, expanded CIK cells in two cultures possessed comparable physiological functions. Notably, significantly higher percentages of CD25⁺ cells and CD69⁺ cells were found in dynamic cultures (P <  0.05). Besides, much higher glucose consumption rate of cells (P <  0.05) but similar Y_Lac/gluc were observed in dynamic cultures. Further, cells in dynamic cultures had better glucose utilization efficiency. Together, these results suggested that dynamic cultures improved cell activation, then accelerated glucose consumption rate, which enhanced cell expansion and promoted glucose utilization efficiency of cells.

Cancer Immunotherapy with Cytokine-Induced Killer Cells

Cytokine-induced killer (CIK) cells form under certain stimulation conditions in cultures of peripheral blood mononuclear cells (PBMCs). They are a heterogeneous immune cell population and contain a high percentage of cells with a mixed T-NK phenotype (CD3+CD56+). The ready availability of a lymphocyte source, together with the high proliferative rate and potent anti-tumor activity of CIK cells, has allowed their use as immunotherapy in a wide variety of neoplasms. Cytotoxicity mediated by CD3+CD56+ T cells depends on the major histocompatibility antigen (MHC)-independent recognition of tumor cells and the activation of signaling pathways through the natural killer group 2 member D (NKG2D) cell-surface receptor. Clinical trials have demonstrated the feasibility and efficacy of CIK cell immunotherapy even in advanced stage cancer patients or those that have not responded to first-line treatment. This review summarizes biological and technical aspects of CIK cells, as well as past and current clinical trials and future trends in this form of immunotherapy.

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.

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.

The Combined Antitumor Effects of 125I Radioactive Particle Implantation and Cytokine-Induced Killer Cell Therapy on Xenograft Hepatocellular Carcinoma in a Mouse Model

The combination of radiotherapy and immunotherapy has shown great promise in eradicating tumors. For example, ¹²⁵I radioactive particle implantation and cytokine-induced killer cell therapies have demonstrated efficacy in treating hepatocellular carcinoma. However, the mechanism of this combination therapy remains unknown. In this study, we utilized cytokine-induced killer cells obtained from human peripheral blood mononuclear cells along with ¹²⁵I radioactive particle implantation to treat subcutaneous hepatocellular carcinoma xenograft tumors in BALB/c nude mice. The effects of combination therapy on tumor growth, tumor cell apoptosis and proliferation, animal survival, and immune indexes were then assessed. The results indicated that ¹²⁵I radioactive particle implantation combined with cytokine-induced killer cells shows a much greater antitumor therapeutic effect than either of the therapies alone when compared to control treatments. Mice treated with a combination of radiotherapy and immunotherapy displayed significantly reduced tumor growth. ¹²⁵I radioactive particle implantation upregulated the expression of major histocompatibility complex (MHC) class I chain-related gene A in hepatocellular carcinoma cells and enhanced cytokine-induced killer cell–mediated apoptosis through activation of caspase-3. Furthermore, cytokine-induced killer cells supplied immune substrates to induce a strong immune response after ¹²⁵I radioactive particle implantation therapy. In conclusion, ¹²⁵I radioactive particle implantation combined with cytokine-induced killer cell therapy significantly inhibits the growth of human hepatocellular carcinoma cells in vivo and improves animal survival times through mutual promotion of antitumor immunity, presenting a promising therapy for hepatocellular carcinoma.

Zoledronic acid sensitizes rhabdomyosarcoma cells to cytolysis mediated by human γδ T cells

Rhabdomyosarcoma (RMS) is the most common type of soft-tissue sarcoma in children. Immunotherapy has been proposed as a treatment for this deadly tumor. In the present study, the cytotoxicity of ex vivo expanded γδ T cells on RMS cell lines was evaluated and the molecular interactions involved were investigated. γδ T cells were expanded in vitro using peripheral blood mononuclear cells from 5 healthy donors and were stimulated with zoledronic acid (Zol) and interleukin 2. RMS cell lines RD and A-673 were used as target cells. The cytotoxicity of the γδ T cells against RMS was assessed in vitro and in vivo. γδ T cells were cytotoxic to RMS cells. Importantly, Zol markedly increased their cytotoxic potential. RMS cells treated with Zol-stimulated γδ T cells to produce interferon γ. γδ T cell-mediated cytotoxicity was primarily through the T cell receptor-dependent signaling pathway in blocking studies. Transfer of γδ T cells together with Zol into nude mice induced the regression of RD tumor xenotransplants. The results of the present study provide the rationale for the clinical evaluation of γδ T cells in RMS.

Generation and characterization of ErbB2-CAR-engineered cytokine-induced killer cells for the treatment of high-risk soft tissue sarcoma in children

Pediatric patients with recurrent, refractory or advanced soft tissue sarcoma (STS) who are simultaneously showing signs of cumulative treatment toxicity are in need of novel therapies. In this preclinical analysis, we identified ErbB2 as a targetable antigen on STS cells and used cytokine-induced killer (CIK) cells transduced with the lentiviral 2^nd-generation chimeric antigen receptor (CAR) vector pS-5.28.z-IEW to target ErbB2-positive tumors. Solely CIK cell subsets with the CD3⁺ T cell phenotype showed up to 85% cell surface expression of the respective CAR. A comparison of wildtype (WT), mock-vector and ErbB2-CAR-CIK cells showed, that engineered cells exhibited diminished in vitro expansion, retained WT CIK cell phenotype with higher percentages of differentiated effector memory/effector cells. Activating natural killer (NK) cell receptor NKG2D-restricted target cell recognition and killing of WT and ErbB2-CAR-CIK cells was maintained against ErbB2-negative tumors, while ErbB2-CAR-CIK cells demonstrated significantly increased cytotoxicity against ErbB2-positive targets, including primary tumors. ErbB2-CAR- but not WT CIK cells proliferated, infiltrated and efficiently lysed tumor cell monolayers as well as 3D tumor spheroids.

Here, we demonstrate a potential cell therapeutic approach using ErbB2-CAR-CIK cells for the recognition and elimination of tumor cells expressing ErbB2, which we identified as a targetable antigen on high-risk STS cells.

Implication of combined PD-L1/PD-1 blockade with cytokine-induced killer cells as a synergistic immunotherapy for gastrointestinal cancer

Cytokine-induced killer (CIK) cells represent a realistic approach in cancer immunotherapy with confirmed survival benefits in the context of metastatic solid tumors. However, therapeutic effects are limited to a fraction of patients. In this study, immune-resistance elements and ideal combination therapies were explored. Initially, phenotypic analysis was performed to document CD3, CD56, NKG2D, DNAM-1, PD-L1, PD-1, CTLA-4, TIM-3, 2B4, and LAG-3 on CIK cells. Upon engagement of CIK cells with the tumor cells, expression of PD-1 on CIK cells and PD-L1 on both cells were up-regulated. Over-expression of PD-L1 levels on tumor cells via lentiviral transduction inhibited tumoricidal activity of CIK cells, and neutralizing of PD-L1/PD-1 signaling axis could enhance their tumor-killing effect. Conversely, blockade of NKG2D, a major activating receptor of CIK cells, largely caused dysfunction of CIK cells. Functional study showed an increase of NKG2D levels along with PD-L1/PD-1 blockade in the presence of other immune effector molecule secretion. Additionally, combined therapy of CIK infusion and PD-L1/PD-1 blockade caused a delay of in vivo tumor growth and exhibited a survival advantage over untreated mice. These results provide a preclinical proof-of-concept for simultaneous PD-L1/PD-1 pathways blockade along with CIK infusion as a novel immunotherapy for unresectable cancers.

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

BACKGROUND

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

PROCEDURE

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

RESULTS

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

CONCLUSIONS

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

Progress and opportunities for immune therapeutics in osteosarcoma

Survival outcomes for osteosarcoma have plateaued since the 1980s, and patients with relapsed or refractory disease have a particularly dismal outcome. Treatment options for these patients are limited primarily due to the paucity of effective therapeutics. Immune therapies such as tumor vaccines and traditional antigen-targeted monoclonal antibodies have had limited success in solid tumors. The recent discovery of novel immune checkpoint blockade strategies and their success in adult cancers has revitalized the use of immunotherapy strategies for the treatment of solid tumors. This paper summarizes existing data supporting the use of immune therapies in osteosarcoma and the progress of this class of drugs in osteosarcoma therapy.

In-vitro influence of mycophenolate mofetil (MMF) and Ciclosporin A (CsA) on cytokine induced killer (CIK) cell immunotherapy

Background

Cytokine-induced-killer (CIK) cells are a promising immunotherapeutic approach for impending relapse following hematopoietic stem cell transplantation (HSCT). However, there is a high risk for treatment failure associated with severe graft versus host disease (GvHD) necessitating pharmaceutical intervention post-transplant. Whether immunosuppression with mycophenolate mofetil (MMF) or Ciclosporin A (CsA) influences the cytotoxic effect of CIK cell immunotherapy is still an open issue.

Methods

CIK cells were generated from PBMC as previously described followed by co-incubation with mycophenolic acid (MPA) or CsA. Proliferation, cytotoxicity and receptor expression were investigated following short- (24 h), intermediate- (3 days) and long-term (7 days) MPA incubation with the intention to simulate the in vivo situation when CIK cells were given to a patient with relevant MPA/CsA plasma levels.

Results

Short-term MPA treatment led to unchanged proliferation capacity and barely had any effect on viability and cytotoxic capability in vitro. The composition of CIK cells with respect to T-, NK-like T- and NK cells remained stable. Intermediate MPA treatment lacked effects on NKG2D, FasL and TRAIL receptor expression, while an influence on proliferation and viability was detectable. Furthermore, long-term treatment significantly impaired proliferation, restricted viability and drastically reduced migration-relevant receptors accompanied by an alteration in the CD4/CD8 ratio. CD3⁺CD56⁺ cells upregulated receptors relevant for CIK cell killing and migration, whereas T cells showed the most interference through significant reductions in receptor expression. Interestingly, CsA treatment had no significant influence on CIK cell viability and the cytotoxic potential against K562.

Conclusions

Our data indicate that if immunosuppressant therapy is indispensable, efficacy of CIK cells is maintained at least short-term, although more frequent dosing might be necessary.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1024-4) contains supplementary material, which is available to authorized users.

A comparison between cytokine- and bead-stimulated polyclonal T cells: the superiority of each and their possible complementary role

Cytokine-induced killer (CIK) cells and T cells expanded by co-stimulation with beads presenting anti-CD3 and -CD28 antibodies are both polyclonal T cells under intensive laboratory and clinical studies, but there has not been any direct comparison between both. We compared the expansion, memory T cell subsets and cytotoxicity for T cells expanded in parallel by the two methods. Bead-stimulated T cells showed superior expansion as compared to CIK cells on D14 of culture. Bead-stimulated T cells consisted of a significantly higher CD4(+) subset and significantly lower CD8(+) subset as compared to CIK cells, as well as a higher proportion of less terminally differentiated T cells and a higher proportion of homing molecules. On the other hand, CIK cells exhibited significantly superior cytotoxicity against two myelomonocytic leukemia cell lines (THP-1 and U937) and two RCC cell lines (786.0 and CaKi-2). The cytotoxicity on D14 against THP-1 was 58.1 % for CIK cells and 8.3 % for bead-stimulated T cells at E:T of 10:1 (p < 0.01). Cytotoxicity correlated positively with the proportion of the CD8 subset in the culture and was independent of NKG2D recognition of susceptible targets. Polyclonal T cells expanded by different methods exhibit different characteristics which may define the specific role of each in different clinical scenario. We postulate that the more potent CIK cells may offer short term benefit while bead-stimulated T cells may offer a more sustained immune response.

The cytotoxic action of the CD56+ fraction of cytokine-induced killer cells against a K562 cell line is mainly restricted to the natural killer cell subset

BACKGROUND

Cytokine-induced killer cells are polyclonal T cells generated ex vivo and comprise two main subsets: the CD56- fraction, possessing an alloreactive potential caused by T cells (CD3+CD56-), and the CD56+ fraction, characterised by a strong antitumour capacity induced by natural killer-like T cells (NK-like T, CD3+CD56+) and natural killer cells (NK, CD3-CD56+ bright).

MATERIALS AND METHODS

We investigated the cytotoxic action of selected CD56+ cell subpopulations against a human chronic myeloid leukaemia (K562) cell line.

RESULTS

After immunomagnetic selection of the CD56+ cell fraction, NK bright cells (CD3-CD56+ bright) and two subsets of NK-like T cells (CD3+CD56+), called NK-like T CD56 dim and NK-like T CD56 bright, could be identified. The cytotoxic effect against K562 cells was mainly exerted by the NK bright subpopulation and resulted to be inversely correlated with the percentage of NK-like T CD56 dim cells in the culture. The lytic action appeared to be independent of cell degranulation as suggested by the lack of change in the expression of CD107a.

DISCUSSION

We conclude that the cytotoxic action of CD56+ cells against a K562 cell line is mainly due to the NK cells.

Effect of cytokine-induced killer cells on immune function in patients with lung cancer

Cytokine-induced killer (CIK) cells have been used as adoptive immunotherapy in cancer. The present study evaluated the effect of CIK cells on immune function in patients with lung cancer. Patients were divided into three groups, according to the treatment received prior to CIK cell treatment: CIK group (no prior treatment), Che-Sur group (prior chemotherapy and surgery) and Che-Rad group (prior chemotherapy and radiotherapy). Following treatment, the average percentage of cluster of differentiation (CD)3⁺CD4⁺, CD3⁺, natural killer (NK) and NKT cells in peripheral blood was significantly higher than that prior to CIK treatment in the Che-Sur and CIK groups, and the levels of interferon-γ in serum were significantly higher than those prior to CIK treatment in the Che-Sur and CIK groups. On the contrary, the levels of interleukin-10 had decreased in these groups following CIK treatment. Subsequently, patients were divided into three groups according to the percentage of CD3⁺CD56⁺ CIK cells that were administered to the patients. The number of NK and NKT cells increased with increasing number of CD3⁺CD56⁺ cells. The patients in the CIK and Che-Sur groups were the most benefited ones following CIK treatment, contrarily to those in the Che-Rad group, since the increase in the number of CD3⁺CD56⁺ CIK cells in the aforementioned patients enhanced the number of NK cells, which exhibit antitumor activity.

Cytokine-induced killer cells as immunotherapy for solid tumors: current evidence and perspectives

Cytokine-induced killer (CIK) cells are ex vivo expanded T lymphocytes endowed with potent MHC-independent antitumor activity. CIK cells are emerging as promising therapeutic approach in the field of cancer adoptive immunotherapy, with biologic features favoring their transferability into clinical applications. Aim of this review is to present the biologic characteristic of CIK cells, discussing the main preclinical findings and initial clinical applications in the field of solid tumors.

Cytomegalovirus-specific cytokine-induced killer cells: concurrent targeting of leukemia and cytomegalovirus

BACKGROUND AIMS

Human cytomegalovirus (CMV) infection and reactivation is a leading complication of allogeneic hematopoietic stem cell transplantation (HSCT). In addition to drug treatment, the adoptive transfer of virus-specific T cells to restore cellular immunity has become a standard therapy after allogeneic HSCT. We recently demonstrated potent anti-leukemic activity of interleukin (IL)-15-activated cytokine-induced killer (CIK) cells. With the use of the same expansion protocol, we asked whether concurrent CMV antigen-pulsing might generate CIK cells with anti-leukemic and anti-CMV activity.

METHODS

CIK cells expanded in the presence of interferon-γ, IL-2, IL-15 and anti-CD3 antibody were pulsed once with CMV(pp65) peptide pool. CMV-specific CIK (CIK(pp65)) and conventional CIK cells were phenotypically and functionally characterized according to their cytokine secretion pattern, degranulation capacity and T-cell receptor (TCR)-mediated and NKG2D-mediated cytotoxicity.

RESULTS

We demonstrated that among CIK cells generated from CMV-seropositive donors, a single stimulation with CMV(pp65) protein co-expanded cytotoxic CMV-specific cells without sacrificing anti-tumor reactivity. Cells generated in this fashion lysed CMV(pp65)-loaded target cells and CMV-infected fibroblasts but also leukemic cells. Meanwhile, the alloreactive potential of CIK(pp65) cells remained low. Interestingly, CMV reactivity was TCR-mediated and CMV-specific cells could be found in CD3(+)CD8(+)CD56(+/-) cytotoxic T-cell subpopulations.

CONCLUSIONS

We provide an efficient method to generate CIK(pp65) cells that may represent a useful cell therapy approach for preemptive immunotherapy in patients who have both an apparent risk of CMV and impending leukemic relapse after allogeneic stem cell transplantation.

The importance of being dead: cell death mechanisms assessment in anti-sarcoma therapy

Cell death can occur through different mechanisms, defined by their nature and physiological implications. Correct assessment of cell death is crucial for cancer therapy success. Sarcomas are a large and diverse group of neoplasias from mesenchymal origin. Among cell death types, apoptosis is by far the most studied in sarcomas. Albeit very promising in other fields, regulated necrosis and other cell death circumstances (as so-called "autophagic cell death" or "mitotic catastrophe") have not been yet properly addressed in sarcomas. Cell death is usually quantified in sarcomas by unspecific assays and in most cases the precise sequence of events remains poorly characterized. In this review, our main objective is to put into context the most recent sarcoma cell death findings in the more general landscape of different cell death modalities.

Role of NKG2D, DNAM-1 and natural cytotoxicity receptors in cytotoxicity toward rhabdomyosarcoma cell lines mediated by resting and IL-15-activated human natural killer cells

Children with advanced stages (relapsed/refractory and stage IV) of rhabdomyosarcoma (RMS) have a poor prognosis despite intensive chemotherapy and autologous stem cell rescue, with 5-year survival rates ranging from 5 to 35 %. Development of new, additional treatment modalities is necessary to improve the survival rate. In this preclinical study, we investigated the potential of resting and cytokine-activated natural killer (NK) cells to lyse RMS cell lines, as well as the pathways involved, to explore the eventual clinical application of (activated) NK cell immunotherapy. RMS cell lines (n = 3 derived from embryonal RMS and n = 2 derived from alveolar RMS) were susceptible to cytolysis mediated by resting NK cells, and this susceptibility was significantly increased using IL-15-activated NK cells. Flow cytometry and cytolytic assays were used to define the activating and inhibitory pathways of NK cells involved in recognizing and lysing RMS cells. NKG2D and DNAM-1 receptor-ligand interactions were essential in cytolysis by resting NK cells, as simultaneous blocking of both pathways resulted in almost complete abrogation of the cytotoxicity. In contrast, combined blocking of DNAM-1 and NKG2D only led to partial reduction of the lytic activity of IL-15-activated NK cells. In this respect, residual lysis was, at least partly, mediated by pathways involving the natural cytotoxicity receptors NKp30 and NKp46. These findings support further exploration of NK cell-based immunotherapy as adjuvant modality in current treatment strategies of RMS.

Adoptive immunotherapy against sarcomas

INTRODUCTION

Conventional treatments reached an unsatisfactory therapeutic plateau in the treatment of advanced unresectable bone and soft tissue sarcomas that remain an unsolved medical need. Several evidences support the concept that adoptive immunotherapy may effectively integrate within the complex and multidisciplinary treatment of sarcomas.

AREAS COVERED

In this work we reviewed adoptive immunotherapy strategies that have been explored in sarcoma settings, with specific focus on issues related to their clinic transferability. We schematically divided approaches based on T lymphocytes specific for MHC-restricted tumor-associated antigens or relying on MHC-independent immune effectors such as natural killer (NK), cytokine-induced killer (CIK) or γδ T cells.

EXPERT OPINION

Preclinical findings and initial clinical reports showed the potentialities and drawbacks of different adoptive immunotherapy strategies. The expansion of tumor infiltrating lymphocytes is difficult to be reproduced outside melanoma. Genetically redirected T cells appear to be a promising option and initial reports are encouraging against patients with sarcomas. Adoptive immunotherapy with MHC-unrestricted effectors such as NK, CIK or γδ T cells has recently shown great preclinical potential in sarcoma setting and biologic features that may favor clinical transferability. Combination of different immunotherapy approaches and integration with conventional treatments appear to be key issues for successful designing of next clinical trials.

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

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

Will post-transplantation cell therapies for pediatric patients become standard of care?

Although allogeneic hematopoietic stem cell transplantation (HSCT) is a curative approach for many pediatric patients with hematologic malignancies and some nonmalignant disorders, some critical obstacles remain to be overcome, including relapse, engraftment failure, graft-versus-host disease (GVHD), and infection. Harnessing the immune system to induce a graft-versus-tumor effect or rapidly restore antiviral immunity through the use of donor lymphocyte infusion (DLI) has been remarkably successful in some settings. Unfortunately, however, the responses to DLI can be variable, and GVHD is common. Thus, manipulations to minimize GVHD while restoring antiviral immunity and enhancing the graft-versus-tumor effect are needed to improve outcomes after allogeneic HSCT. Cellular therapies, defined as treatment modalities in which hematopoietic or nonhematopoietic cells are used as therapeutic agents, offer this promise for improving outcomes post-HSCT. This review presents an overview of the field for pediatric cell therapies in the transplant setting and discusses how we can broaden applicability beyond phase I.

Immunomagnetic selection or irradiation eliminates alloreactive cells but also reduces anti-tumor potential of cytokine-induced killer cells: implications for unmanipulated cytokine-induced killer cell infusion

BACKGROUND AIMS

Cytokine-induced killer (CIK) cells may offer a novel therapeutic approach for patients with malignancies relapsing after allogeneic stem cell transplantation. Although CIK cells display negligible alloreactivity and cause minimal graft versus-host-disease (GVHD), high CIK cell doses required during relapse may pose a risk for severe GVHD, specifically in the mismatched or haploidentical transplantation setting. Manipulation of CIK cells may reduce risk for GVHD without affecting the anti-tumor potential.

METHODS

In this pre-clinical study, we provide a detailed functional comparison of conventional and irradiated, CD56-enriched or T-cell receptor α/β-depleted CIK cells.

RESULTS

In vitro analysis showed retained anti-leukemic and anti-tumor potential after CIK cell manipulation. Even being sequentially infused into immunodeficient mice grafted with malignant cells, cytotoxic effects were fewest after irradiation but were improved by CD56 enrichment and were best with conventional CIK cells. Hence, considering the proliferative capacity of inoculated malignancies and effector cells, a single dose of conventional CIK cells resulted in prolonged disease-free survival and elimination of rhabdomyosarcoma cells, whereas sequential infusions were needed to achieve comparable results in leukemia-bearing mice. However, this mouse model has limitations: highly effective conventional CIK cells demonstrated both limited xenogenic GVHD and low alloreactive potential in vitro.

CONCLUSIONS

Our study revealed that conventional CIK cells demonstrate no significant alloreactive potential but provide the strongest anti-tumor efficacy compared with manipulated CIK cells. Conventional CIK cells may therefore be tested in high numbers and short-term intervals in patients with impending relapse even after mismatched transplantation.

Implication of different effector mechanisms by cord blood-derived and peripheral blood-derived cytokine-induced killer cells to kill precursor B acute lymphoblastic leukemia cell lines

BACKGROUND AIMS

Cytokine-induced killer (CIK) cells ex vivo-expanded from cord blood (CB) or peripheral blood (PB) have been shown to be cytotoxic against autologous and allogeneic tumor cells. We have previously shown that CD56(+) CIK cells (CD3(+)CD56(+) and CD3(-)CD56(+)) are capable of killing precursor B-cell acute lymphoblastic leukemia (B-ALL) cell lines. However, the lytic pathways used by CD56(+) PB and CB-CIK cells to kill B-ALL cell lines have not been studied.

METHODS

CB and PB-CIK cells were differentiated. CD56(+) CB- and PB-CIK cells were compared for expression of different phenotypic markers and for the lytic pathways used to kill B-ALL cell lines.

RESULTS

We found that cytotoxic granule proteins were expressed at higher levels in CD56(+) PB-CIK than in CD56(+) CB-CIK cells. However, CD56(+) CB-CIK cells expressed more tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) compared with CD56(+) PB-CIK cells. We observed that CD56(+) CB-CIK cells used both the NKG2D and TRAIL cytotoxic pathways and were more effective at killing REH cells than CD56(+) PB-CIK cells that used only the NKG2D pathway. In contrast, CD56(+) PB-CIK cells used both NKG2D and TRAIL pathways to kill NALM6 cells, whereas CD56(+) CB-CIK cells used only the NKG2D pathway.

CONCLUSIONS

Our results suggest that both the source of CIK and the type of B-ALL cell line have an impact on the intensity of the cytolytic activity and on the pathway used. These findings may have clinical implications with respect to optimizing therapeutic efficacy, which may be dependent on the source of the CIK cells and on the target tumor cells.

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

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

Cytokine-induced killer cells eradicate bone and soft-tissue sarcomas

Unresectable metastatic bone sarcoma and soft-tissue sarcomas (STS) are incurable due to the inability to eradicate chemoresistant cancer stem-like cells (sCSC) that are likely responsible for relapses and drug resistance. In this study, we investigated the preclinical activity of patient-derived cytokine-induced killer (CIK) cells against autologous bone sarcoma and STS, including against putative sCSCs. Tumor killing was evaluated both in vitro and within an immunodeficient mouse model of autologous sarcoma. To identify putative sCSCs, autologous bone sarcoma and STS cells were engineered with a CSC detector vector encoding eGFP under the control of the human promoter for OCT4, a stem cell gene activated in putative sCSCs. Using CIK cells expanded from 21 patients, we found that CIK cells efficiently killed allogeneic and autologous sarcoma cells in vitro. Intravenous infusion of CIK cells delayed autologous tumor growth in immunodeficient mice. Further in vivo analyses established that CIK cells could infiltrate tumors and that tumor growth inhibition occurred without an enrichment of sCSCs relative to control-treated animals. These results provide preclinical proof-of-concept for an effective strategy to attack autologous sarcomas, including putative sCSCs, supporting the clinical development of CIK cells as a novel class of immunotherapy for use in settings of untreatable metastatic disease.

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

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

Allogeneic stem cell transplantation for patients with advanced rhabdomyosarcoma: a retrospective assessment

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (allo-SCT) may provide donor cytotoxic T cell-/NK cell-mediated disease control in patients with rhabdomyosarcoma (RMS). However, little is known about the prevalence of graft-vs-RMS effects and only a few case experiences have been reported.

METHODS

We evaluated allo-SCT outcomes of 30 European Group for Blood and Marrow Transplantation (EBMT)-registered patients with advanced RMS regarding toxicity, progression-free survival (PFS) and overall survival (OS) after allo-SCT. Twenty patients were conditioned with reduced intensity and ten with high-dose chemotherapy. Twenty-three patients were transplanted with HLA-matched and seven with HLA-mismatched grafts. Three patients additionally received donor lymphocyte infusions (DLIs). Median follow-up was 9 months.

RESULTS

Three-year OS was 20% (s.e.±8%) with a median survival time of 12 months. Cumulative risk of progression was 67% (s.e.±10%) and 11% (s.e.±6%) for death of complications. Thirteen patients developed acute graft-vs-host disease (GvHD) and five developed chronic GvHD. Eighteen patients died of disease and four of complications. Eight patients survived in complete remission (CR) (median: 44 months). No patients with residual disease before allo-SCT were converted to CR.

CONCLUSION

The use of allo-SCT in patients with advanced RMS is currently experimental. In a subset of patients, it may constitute a valuable approach for consolidating CR, but this needs to be validated in prospective trials.

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

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

Survivin blockade sensitizes rhabdomyosarcoma cells for lysis by fetal acetylcholine receptor-redirected T cells

Cellular immunotherapy may provide a strategy to overcome the poor prognosis of metastatic and recurrent rhabdomyosarcoma (RMS) under the current regimen of polychemotherapy. Because little is known about resistance mechanisms of RMS to cytotoxic T cells, we investigated RMS cell lines and biopsy specimens for expression and function of immune costimulatory receptors and anti-apoptotic molecules by RT-PCR, Western blot analysis, IHC, and cytotoxicity assays using siRNA or transfection-modified RMS cell lines, together with engineered RMS-directed cytotoxic T cells specific for the fetal acetylcholine receptor. We found that costimulatory CD80 and CD86 were consistently absent from all RMSs tested, whereas inducible T-cell co-stimulator ligand (ICOS-L; alias B7H2) was expressed by a subset of RMSs and was inducible by tumor necrosis factor α in two of five RMS cell lines. Anti-apoptotic survivin, along with other inhibitor of apoptosis (IAP) family members (cIAP1, cIAP2, and X-linked inhibitor of apoptosis protein), was overexpressed by RMS cell lines and biopsy specimens. Down-regulation of survivin by siRNA or pharmacologically in RMS cells increased their susceptibility toward a T-cell attack, whereas induction of ICOS-L did not. Treatment of RMS-bearing Rag(-/-) mice with fetal acetylcholine receptor-specific chimeric T cells delayed xenograft growth; however, this happened without definitive tumor eradication. Combined blockade of survivin and application of chimeric T cells in vivo suppressed tumor proliferation during survivin inhibition. In conclusion, survivin blockade provides a strategy to sensitize RMS cells for T-cell-based therapy.

Intraperitoneal perfusion of cytokine-induced killer cells with local hyperthermia for advanced hepatocellular carcinoma

AIM: To study the effect and tolerance of intraperitoneal perfusion of cytokine-induced killer (CIK) cells in combination with local radio frequency (RF) hyperthermia in patients with advanced primary hepatocellular carcinoma (HCC).

METHODS: Patients with advanced primary HCC were included in this study. CIK cells were perfused intraperitoneal twice a week, using 3.2 × 10⁹ to 3.6 × 10⁹ cells each session. Local RF hyperthermia was performed 2 h after intraperitoneal perfusion. Following an interval of one month, the next course of treatment was administered. Patients received treatment until disease progression. Tumor size, immune indices (CD3⁺, CD4⁺, CD3⁺CD8⁺, CD3⁺CD56⁺), alpha-fetoprotein (AFP) level, abdominal circumference and adverse events were recorded. Time to progression and overall survival (OS) were calculated.

RESULTS: From June 2010 to July 2011, 31 patients diagnosed with advanced primary HCC received intraperitoneal perfusion of CIK cells in combination with local RF hyperthermia in our study. Patients received an average of 4.2 ± 0.6 treatment courses (range, 1-8 courses). Patients were followed up for 8.3 ± 0.7 mo (range, 2-12 mo). Following combination treatment, CD4⁺, CD3⁺CD8⁺ and CD3⁺CD56⁺ cells increased from 35.78% ± 3.51%, 24.61% ± 4.19% and 5.94% ± 0.87% to 45.83% ± 2.48% (P = 0.016), 39.67% ± 3.38% (P = 0.008) and 10.72% ± 0.67% (P = 0.001), respectively. AFP decreased from 167.67 ± 22.44 to 99.89 ± 22.05 ng/mL (P = 0.001) and abdominal circumference decreased from 97.50 ± 3.45 cm to 87.17 ± 4.40 cm (P = 0.002). The disease control rate was 67.7%. The most common adverse events were low fever and slight abdominal erubescence, which resolved without treatment. The median time to progression was 6.1 mo. The 3-, 6- and 9-mo and 1-year survival rates were 93.5%, 77.4%, 41.9% and 17.4%, respectively. The median OS was 8.5 mo.

CONCLUSION: Intraperitoneal perfusion of CIK cells in combination with local RF hyperthermia is safe, can efficiently improve immunological status, and may prolong survival in HCC patients.

Review of Chinese clinical trials on CIK cell treatment for malignancies

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

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.

Cell death pathways as therapeutic targets in rhabdomyosarcoma

Resistance of rhabdomyosarcoma to current therapies remains one of the key issues in pediatric oncology. Since the success of most cytotoxic therapies in the treatment of cancer, for example, chemotherapy, depends on intact signaling pathways that mediate programmed cell death (apoptosis), defects in apoptosis programs in cancer cells may result in resistance. Evasion of apoptosis in rhabdomyosarcoma may be caused by defects in the expression or function of critical mediators of apoptosis or in aberrant expression of antiapoptotic proteins. Therefore, the identification of the molecular mechanisms that confer primary or acquired resistance to apoptosis in rhabdomyosarcoma presents a critical step for the rational development of molecular targeted drugs. This approach will likely open novel perspectives for the treatment of rhabdomyosarcoma.

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

BACKGROUND AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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