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

Safety and Therapeutic Outcomes of Adjuvant Immunotherapy With Autologous Cytokine-induced Killer Cells for Patients With Hepatocellular Carcinoma Beyond Milan Criteria After Liver Transplantation

BACKGROUND

Adjuvant immunotherapy with autologous cytokine-induced killer (CIK) cells for hepatocellular carcinoma (HCC) remains understudied in liver transplant patients because of potential risks of acute rejection and diminished efficacy by immunosuppression.

METHODS

This study examined the safety and effectiveness of CIK therapy in patients with HCC exceeding the Milan criteria, treated at 2 Korean hospitals between 2019 and 2021. We analyzed clinical outcomes of 16 patients who underwent CIK therapy compared with 44 propensity-matched controls who did not receive CIK therapy. CIK cells were administered in 6 escalating doses, either 3 or 6 times over the course of weeks 4, 5, 6, 8, 10, and 12 posttransplantation.

RESULTS

CIK therapy was well-tolerated without significant treatment-related adverse reactions. Maximal tolerated dose of CIK cells was 10 × 109, which had been repeated 6 times. The CIK group exhibited higher 2-y HCC recurrence-free (87.5% versus 62.9%, P = 0.027) and patient survival (100% versus 81.5%, P = 0.002) rates, with no significant difference in rejection-free survival rates (92.9% versus 95.0%, P = 0.926) compared with the no-CIK group. Subgroup analysis showed that the CIK group in patients with high retreat scores, elevated R3-α-fetoprotein scores, and those beyond the University of California San Francisco criteria had improved HCC recurrence-free survival. Immunological evaluation showed elevated CD8+ T cells and polymorphonuclear myeloid-derived suppressor cells with transient increases in granzyme B and tumor necrosis factor-α levels in the CIK group.

CONCLUSIONS

These findings advocate CIK therapy as a safe and effective, potential adjuvant treatment for HCC beyond Milan criteria after transplantation, supporting further validation trials.

The antitumor effect of extracellular vesicles derived from cytokine-activated CD8+ T cells

Extracellular vesicles (EVs) are nano-sized membrane particles secreted by various cell types that are involved in many important cellular processes. Recently, EVs originating from immune cells, such as dendritic cells, chimeric antigen receptor T cells, and natural killer cells, have attracted much attention because of their known direct and indirect antitumor activity. Here, we report the EVs released by cytokine-activated CD8+ T (caCD8) cells and its cytotoxicity against cancer cells. CaCD8 cells can release EVs following stimulation of CD8+ T cells with an anti-CD3 antibody and a cytokine cocktail ex vivo. The isolated vesicles have typical EV characteristics, such as an oval shape and a size distribution between 30 and 200 nm, as well as CD81 expression. Notably, caCD8-EVs displayed cytotoxicity against various cancer cells in vitro. Furthermore, mechanism analysis demonstrates that caCD8-EVs not only contain typical cytotoxic proteins (i.e. granzyme B and perforin), but also significantly enrich interferon γ (IFNγ) compared with caCD8 cells. EV-derived IFNγ participates in EV-induced apoptosis in cancer cells. Therefore, our data reveal antitumor effects of EVs secreted from caCD8 cells and the potential role of the EV-derived IFNγ.

Generation of dual-attribute iTNK cells from hPSCs for cancer immunotherapy

Dual-attribute immune cells possess advantageous features of cytotoxic T cells and natural killer (NK) cells and hold promise for advancing immunotherapy. Dual-attribute cell types such as invariant natural killer T cells, induced T-to-NK cells, and cytokine-induced killer cells have demonstrated efficacy and safety in preclinical and clinical studies. However, their limited availability hinders their widespread application. Human pluripotent stem cells (hPSCs) offer an ideal source. Here, we generate dual-attribute induced T-NK (iTNK) cells from hPSCs, expressing markers of both cytotoxic T and NK cells. Single-cell RNA and T cell receptor (TCR) sequencing analyses reveal that iTNK cells expressed signature genes associated with both NK and T cells and displayed a diverse TCR repertoire. iTNK cells release cytotoxic mediators, exert cytotoxicity against diverse tumor cell lines, and inhibit tumor growth in vivo. By harnessing adaptive and innate immune responses, hPSC-derived iTNK cells offer promising strategies for cancer immunotherapy.

Cytokine-induced killer cells: new insights for therapy of hematologic malignancies

BACKGROUND

Cytokine-induced killer (CIK) cells are a novel subgroup of immune effectors, classified as one of the modified T cell-mediated arms for immunotherapy. These cells exert MHC-unrestricted cytotoxicity against both hematological and solid malignancies with low incidence of treatment-related severe complications. This study reviews the application of CIK cells in treating cases with hematologic malignancies.

MAIN BODY

CIK cells consist of CD3+/CD56+  natural killer (NK) T cells, CD3-/CD56+ NK cells, and CD3+/CD56- cytotoxic T cells. In this regard, the CD3+/CD56+  NK T cells are the primary effectors. Compared with the previously reported antitumor immune cells, CIK cells are characterized by improved in vitro proliferation and amplification, enhanced migration and invasive capacity to tumor region, more significant antitumor activity, and a broader antitumor spectrum. CIK cells can also induce death in tumor cells via numerous pathways and mechanisms. Hence, CIKs-based therapy has been used in various clinical trials and has shown efficacy with a very low graft versus host disease (GVHD) against several cancers, such as hematologic malignancies, even in relapsing cases, or cases not responding to other therapies. Despite the high content of T cells, CIK cells induce low alloreactivity and, thus, pose a restricted threat of GVHD induction even in MHC-mismatched transplantation cases. Phase 1 and 2 clinical trials of CIK cell therapy have also highlighted satisfactory therapeutic advantages against hematologic cancers, indicating the safety of CIK cells even in haploidentical transplantation settings.

CONCLUSION

CIK cells have shown promising results in the treatment of hematologic malignancies, especially in combination with other antitumor strategies. However, the existing controversies in achieving desired clinical responses underscore the importance of future studies.

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.

Cytokine-Induced Killer Cells in Combination with Heat Shock Protein 90 Inhibitors Functioning via the Fas/FasL Axis Provides Rationale for a Potential Clinical Benefit in Burkitt's lymphoma

Constant efforts are being made to develop methods for improving cancer immunotherapy, including cytokine-induced killer (CIK) cell therapy. Numerous heat shock protein (HSP) 90 inhibitors have been assessed for antitumor efficacy in preclinical and clinical trials, highlighting their individual prospects for targeted cancer therapy. Therefore, we tested the compatibility of CIK cells with HSP90 inhibitors using Burkitt's lymphoma (BL) cells. Our analysis revealed that CIK cytotoxicity in BL cells was augmented in combination with independent HSP90 inhibitors 17-DMAG (17-dimethylaminoethylamino-17-demethoxygeldanamycin) and ganetespib. Interestingly, CIK cell cytotoxicity did not diminish after blocking with NKG2D (natural killer group 2, member D), which is a prerequisite for their activation. Subsequent analyses revealed that the increased expression of Fas on the surface of BL cells, which induces caspase 3/7-dependent apoptosis, may account for this effect. Thus, we provide evidence that CIK cells, either alone or in combination with HSP90 inhibitors, target BL cells via the Fas-FasL axis rather than the NKG2D pathway. In the context of clinical relevance, we also found that high expression of HSP90 family genes (HSP90AA1, HSP90AB1, and HSP90B1) was significantly associated with the reduced overall survival of BL patients. In addition to HSP90, genes belonging to the Hsp40, Hsp70, and Hsp110 families have also been found to be clinically significant for BL survival. Taken together, the combinatorial therapy of CIK cells with HSP90 inhibitors has the potential to provide clinical benefits to patients with BL.

Immunophenotype and antitumor activity of cytokine-induced killer cells from patients with hepatocellular carcinoma

BACKGROUND

Cytokine-induced killer (CIK) cells are heterogeneous lymphocytes from human peripheral blood mononucleated cells (PBMCs) co-cultured with several cytokines. The main purpose of this study is to evaluate the functional characteristics and anticancer ability of CIK cells from hepatocarcinoma (HCC) patients.

METHODS

CIK cells were activated ex-vivo and expanded from PBMCs from HCC patients. The immunophenotype and the ex-vivo killing ability of CIK cells were evaluated. Human CIK cells were intravenously injected into NOD/SCID mice to evaluate the in vivo anticancer ability.

RESULTS

More than 70% of CIK cells were CD3+CD8+, and 15%-30% were CD3+CD56+. These cells expressed an increased number of activated natural killer (NK) receptors, such as DNAM1 and NKG2D, and expressed low-immune checkpoint molecules, including PD-1, CTLA-4, and LAG-3. Among the chemokine receptors expressed by CIKs, CXCR3 and CD62L were elevated in CD8+ T cells, representing the trafficking ability to inflamed tumor sites. CIK cells possess the ex-vivo anticancer activity to different cell lines. To demonstrate in vivo antitumor ability, human CIK cells could significantly suppress the tumor of J7 bearing NOD/SCID mice. Furthermore, human immune cells could be detected in the peripheral blood and on the tumors after CIK injection.

CONCLUSIONS

This study revealed that CIK cells from HCC patients possess cytotoxic properties, and express increased levels of effector NK receptors and chemokine molecules and lower levels of suppressive checkpoint receptors. CIK cells can suppress human HCC ex-vivo and in vivo. Future clinical trials of human CIK cell therapy for HCC are warranted.

Case Report: Chemotherapy and Radiotherapy Combined With DC-CIK for Pulmonary and Mediastinal Metastases From Nasopharyngeal Carcinoma

Introduction

The optimal treatment for pulmonary and mediastinal metastasis of nasopharyngeal carcinoma (NPC) is still controversial, and the therapeutic effect is poor recently. In one case, we demonstrated a long-term survival after postoperative chemoradiotherapy combined with dendritic cell and cytokine-induced killer (DC-CIK) immunotherapy for pulmonary and mediastinal metastases from NPC.

Baseline Characteristics

A 53-year-old woman was admitted to our hospital in June 2008. Pathological biopsy revealed a poorly differentiated squamous cell carcinoma located in the nasopharynx with the invasion of internal pterygoid muscles, the sphenoid bone, and unilateral neck lymph node metastasis. No distant metastases were observed. The stage of NPC was T3N1M0 III (AJCC8). The patient received concurrent chemoradiotherapy for primary lesion and neck lymph nodes and achieved complete remission (CR) of the disease after 3 months. Follow-up at 3-month intervals was carried out. Pulmonary and mediastinal lymph node metastases were found in July 2009. The patient then underwent right upper lobectomy and mediastinal lymph node dissection and five cycles of gemcitabine and cisplatin (GP) regimen chemotherapy, following radiotherapy and DC-CIK immunotherapy.

Results

After a follow-up time of 13 years, no tumor recurrence or metastasis and severe adverse reactions were found.

Conclusion

Postoperative chemotherapy and radiotherapy in combination with DC-CIK immunotherapy may produce a synergistic therapeutic effect on patients with mediastinal lymph node metastasis from NPC.

NKG2D Engagement Alone Is Sufficient to Activate Cytokine-Induced Killer Cells While 2B4 Only Provides Limited Coactivation

Cytokine-induced killer (CIK) cells are an ex vivo expanded heterogeneous cell population with an enriched NK-T phenotype (CD3+CD56+). Due to the convenient and relatively inexpensive expansion capability, together with low incidence of graft versus host disease (GVHD) in allogeneic cancer patients, CIK cells are a promising candidate for immunotherapy. It is well known that natural killer group 2D (NKG2D) plays an important role in CIK cell-mediated antitumor activity; however, it remains unclear whether its engagement alone is sufficient or if it requires additional co-stimulatory signals to activate the CIK cells. Likewise, the role of 2B4 has not yet been identified in CIK cells. Herein, we investigated the individual and cumulative contribution of NKG2D and 2B4 in the activation of CIK cells. Our analysis suggests that (a) NKG2D (not 2B4) is implicated in CIK cell (especially CD3+CD56+ subset)-mediated cytotoxicity, IFN-γ secretion, E/T conjugate formation, and degranulation; (b) NKG2D alone is adequate enough to induce degranulation, IFN-γ secretion, and LFA-1 activation in CIK cells, while 2B4 only provides limited synergy with NKG2D (e.g., in LFA-1 activation); and (c) NKG2D was unable to costimulate CD3. Collectively, we conclude that NKG2D engagement alone suffices to activate CIK cells, thereby strengthening the idea that targeting the NKG2D axis is a promising approach to improve CIK cell therapy for cancer patients. Furthermore, CIK cells exhibit similarities to classical invariant natural killer (iNKT) cells with deficiencies in 2B4 stimulation and in the costimulation of CD3 with NKG2D. In addition, based on the current data, the divergence in receptor function between CIK cells and NK (or T) cells can be assumed, pointing to the possibility that molecular modifications (e.g., using chimeric antigen receptor technology) on CIK cells may need to be customized and optimized to maximize their functional potential.

Increase of Antitumoral Effects of Cytokine-Induced Killer Cells by Antibody-Mediated Inhibition of MICA Shedding

Natural killer group 2D (NKG2D) receptor plays a pivotal role in cytokine-induced killer (CIK) cell-mediated cytotoxicity against malignancies, and the expression of NKG2D ligands might allow targets to be more susceptible to the CIK cell-mediated destruction. In this study, we investigated the synergistic effects of CIK cells antitumor activity and antibody-mediated inhibition of MICA/B shedding. This monoclonal antibody (7C6) has been previously shown to be able to specifically target MICA/B a3 domain on tumor cells, resulting in the increase in cell surface MICA/B expression by inhibition of their shedding. In the current study, we show that 7C6 antibody could substantially inhibit MICA shedding and stabilize the expression of MICA/B on Hela cells and MDA-MB-231 cells. In combination with 7C6, CIK cells showed higher degranulation rate, more IFN-γ production and elevated cytotoxic capacity against tumor cells. Furthermore, we demonstrate that NKG2D-MICA/B ligation could lead to activation of both CD3+ CD56− T cells and CD3+CD56+ NKT subset cells of CIK culture and NKT subset was more sensitive to NKG2D signaling than the counterpart T cells. 7C6-mediated inhibition of MICA shedding could strengthen this signal and eventually enhance the antitumor activity of CIK cells. With multiple advantages of easy ex vivo expansion, minor GVHD, natural tumor trafficking and non-MHC restricted, CIK cell-based therapy may serve as a potent combination partner with MICA antibody-mediated immunotherapy.

Application of the chemokine-chemokine receptor axis increases the tumor-targeted migration ability of cytokine-induced killer cells in patients with colorectal cancer

Cytokine-induced killer (CIK) cells are a group of heterogeneous immune cells which can be isolated from human peripheral blood mononuclear cells and have demonstrated therapeutic benefit both in hematologic malignancies and solid tumors, including colorectal cancer. However, poor tumor-targeted migration has limited the clinical efficacy of CIK cell treatment. The chemokine-chemokine receptor (CK-CKR) axis serves a role in the tumor-directed trafficking capacity of immune cells. Investigating the relationship between CKR profiles on the surface of CIK cells and chemokine expression levels in the tumor microenvironment may improve CIK cell therapy. In the present study, the spectrum of chemokine expression levels in tumor tissues from patients with colorectal cancer (CRC) and CKR expression profiles in CIK cells obtained from the same individuals with CRC were investigated. The results showed that chemokine expression levels in tumor tissues exhibited variability and cell line heterogeneity. However, the expression levels of a number of chemokines were similar in different CRC donors and cell lines. Expression levels of CXCLL10, CXCL11 and CCL3 were significantly higher in most tumor tissues compared with adjacent normal tissues and highly expressed in most CRC cell lines. In accordance with chemokine expression levels, CKR profiles on the surface of CIK cells also showed donor-to-donor variability. However, concordant expression profiles of CKRs were identified in different patients with CRC. CXCR3 and CXCR4 were highly expressed on the surface of CIK cells through the culture process. Importantly, the expression levels of all CKRs, especially CCR4, CXCR4 and CXCR3, were notably decreased during the course of CIK cell expansion. The changing trend of CKR profiles were not correlated with the chemokine expression profiles in CRC tissues (CCL3, CXCL12 and CXCL10/CXCL11 were highly expressed in CRC tissue). Re-stimulating CIK cells using chemokines (CCL21 and CXCL11) at the proper time point increased corresponding CKR expression levels on the surface of CIK cells and enhance tumor-targeted trafficking in vitro. These results demonstrated that modification of the CK-CKR axis using exogenous recombinant chemokines at the proper time point enhanced CIK cell trafficking ability and improved CIK antitumor effects.

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.

A novel simplified method of generating cytomegalovirus-specific cytokine-induced killer cells of high specificity and superior potency with GMP compliance

We describe a method of rendering polyclonal cytokine-induced killer cells (CIK) specific against cytomegalovirus (CMV), focusing on GMP compliance. Peripheral blood mononuclear cells (PBMNC) are stimulated with pooled CMV peptides pp65 and IE-1 for 16-24 h and the reactive T cell subset which up-regulate CD137 is further co-stimulated with anti-CD137, followed by expansion in G-Rex flasks under standard CIK culture condition. This method generates a large number CMV-specific CIK with superior potency compared to published method currently in clinical trials. The cytotoxicity as measured by chromium release assay correlates with the upregulation of CD107a upon peptide re-challenge as measured by flow cytometry. CMV-CIK at maturity consist of mainly late effector memory CD8 T cells and have a skewed TCR repertoire with preferential expansion of a few families. Such CMV-CIK retain their function after freezing and thawing. CMV-CIK thus generated is ready for clinical trial against drug-resistant CMV disease.

High-affinity T cell receptors redirect cytokine-activated T cells (CAT) to kill cancer cells

Cytokine-activated T cells (CATs) can be easily expanded and are widely applied to cancer immunotherapy. However, the good efficacy of CATs is rarely reported in clinical applications because CATs have no or very low antigen specificity. The low-efficacy problem can be resolved using T cell antigen receptor-engineered CAT (TCR-CAT). Herein, we demonstrate that NY-ESO-1_157-165 HLA-A*02:01-specific high-affinity TCR (HAT)-transduced CATs can specifically kill cancer cells with good efficacy. With low micromolar range dissociation equilibrium constants, HAT-transduced CATs showed good specificity with no off-target killing. Furthermore, the high-affinity TCR-CATs delivered significantly better activation and cytotoxicity than the equivalent TCR-engineered T cells (TCR-Ts) in terms of interferon-γ and granzyme B production and in vitro cancer cell killing ability. TCR-CAT may be a very good alternative to the expensive TCR-T, which is considered an effective personalized cyto-immunotherapy.

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.

Retrospective analysis of the efficacy of adjuvant CIK cell therapy in epithelial ovarian cancer patients who received postoperative chemotherapy

Cytokine-induced killer (CIK) cells are demonstrated to possess potent cytolytic effect against ovarian cancer cells in vitro and in vivo. However, the clinical efficacy of maintenance therapy of CIK cells in patients with epithelial ovarian cancer (EOC) after first-line treatment remains unclear. This retrospective study included 646 cases of postoperative EOC patients, 72 of which received chemotherapy and sequential immunotherapy (CIT group), and 574 of which received only chemotherapy (Control group). Patients in the CIT group received at least four cycles of CIK cell (range 8.0 × 10⁹ – 1.3 × 10¹⁰ cells) transfusion, with the interval of each cycle being 2 weeks. Survival analysis showed a significantly higher overall survival (OS) rate in the CIT group compared with the control group, as well as a favorable progression-free survival (PFS). Univariate and multivariate analyses indicated that adjuvant CIT was an independent prognostic factor for the OS of patients with EOC. Furthermore, subgroup analyses showed that adjuvant CIT significantly improved the OS of patients older than 45 years, with CA125 ≤ 1000, or with moderate or poorly differentiated tumors, and prolonged the PFS of patients with residual disease > 1 cm. Additionally, Kaplan-Meier analyses revealed that a higher fraction of CD3⁺CD8⁺/CD3⁺CD56⁺ phenotypes or lower percentage of CD3⁺CD4⁺/CD3⁻CD56⁺ phenotypes in the infused CIK cells significantly associated with better survival of patients with EOC. Furthermore, across all processes of CIK cell immunotherapy in the CIT group, 12.5% (9/72) of patients developed self-limiting light fevers and shivering at grade 1 or 2. No immunotherapy-related serious reactions were recorded. These data indicate that adjuvant CIT with CIK cells is an effective therapeutic approach to prolonging the survival of EOC patients.

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.

Safety and activity of PD-1 blockade-activated DC-CIK cells in patients with advanced solid tumors

Cytokine-induced killer (CIK) cells that are stimulated using mature dendritic cells (DCs), referred to as (DC-CIK cells) exhibit superior anti-tumor potency. Anti-programmed death-1 (PD-1) antibodies reinvigorate T cell-mediated antitumor immunity. This phase I study aimed to assess the safety and clinical activity of immunotherapy with PD-1 blockade (pembrolizumab)-activated autologous DC-CIK cells in patients with advanced solid tumors. Patients with selected types of advanced solid tumors received a single intravenous infusion of activated autologous DC-CIK cells weekly for the first month and every 2 weeks thereafter. The primary end points were safety and adverse event (AE) profiles. Antitumor responses, overall survival (OS), progression-free survival (PFS) and cytolytic activity were secondary end points. Treatment-related AEs occurred in 20/31 patients. Grade 3 or 4 toxicities, including fever and chills, were observed in two patients. All treatment-related AEs were reversible or controllable. The cytotoxicity of DC-CIK cells induced up-regulation of PD-L1 expression on autologous tumor cells. When activated using pembrolizumab ex vivo, DC-CIK cells exerted superior antitumor properties and elevated IFN-γ secretion. Objective responses (complete or partial responses) were observed in 7 of the 31patients.These responses were durable, with 6 of 7 responses lasting more than 5 months. The overall disease control rate in the patients was 64.5%. At the time of this report, the median OS and PFS were 270 and 162 days, respectively. In conclusions, treatment with pembrolizumab-activated autologous DC-CIK cells was safe and exerted encouraging antitumor activity in advanced solid tumors. A larger phase II trial is warranted.

The progress and current status of immunotherapy in acute myeloid leukemia

Recently, there has been remarkable progress in basic and preclinical studies of acute myeloid leukemia (AML). The improved outcomes of AML can largely be attributed to advances in supportive care and hematopoietic cell transplantation as opposed to conventional chemotherapy. However, as the 5-year survival rate remains low due to a high incidence of relapse, novel and effective treatments are urgently needed. Increasing attention is focusing on identifying suitable immunotherapeutic strategies for AML. Here, we describe the immunological features, mechanisms of immune escape, and recent progress in immunotherapy for AML. Problems encountered in the clinic will also be discussed. Although current outcomes may be limited, ongoing preclinical or clinical efforts are aimed at improving immunotherapy modalities and designing novel therapies, such as vaccines, monoclonal antibody therapy, chimeric antibody receptor-engineered T cells (CAR-T), TCR-engineered T cells (TCR-T), and checkpoint inhibitors, which may provide promising and effective therapies with higher specificity and efficacy for AML.

The Efficacy of CIK-Based Immunotherapies for Advanced Solid Tumors

OBJECTIVE

To investigate the efficacy of cytokine-induced killer cell-based immunotherapies in patients with advanced malignant solid tumors and the difference in clinical efficiency among 3 kinds of cytokine-induced killer cell-based immunotherapies.

METHODS

One hundred forty-six cases with advanced solid tumor, 230 cycles of cytokine-induced killer cell-based immunotherapies, were involved in this study. T-lymphocyte subsets, carcinoembryonic antigen, and adverse reactions were recorded.

RESULTS

CD3+ T lymphocyte, Th, NKT, and Th/Tc were increased after cytokine-induced killer cell-based treatment, from 55.67 ± 3.64 to 84.12 ± 5.15, 26.56 ± 4.47 to 42.76 ± 3.68, 1.82 ± 0.58 to 7.08 ± 0.92, 0.79 ± 3.64 to 1.35 ± 0.20, respectively ( P < .001). Carcinoembryonic antigen was decreased from 398.39 ± 219.16 to 127.26 ± 153.41 ( P < .001). Difference values were greater than 0 ( P < .001). Difference value of carcinoembryonic antigen was obviously less than 0 ( P < .001). There was no obvious difference in all variations between cytokine-induced killer cell and DC+CIK groups ( P > .05). The highest amount of CD3+ T lymphocyte and Th was recorded after at least 4 cycles of immunotherapy. And CD8+ T/CD4+ T also began to decrease after 4 cycles of immunotherapy. Difference value of T lymphocyte and Tc of patients with surgery is higher than that of patients without surgery.

CONCLUSION

Cytokine-induced killer cell-based immunotherapy is capable of increasing T-lymphocyte subsets, recovering cellular immunity without severe side effects, and is suitable for different kinds of solid cancer. Clinical efficiency of cytokine-induced killer cell-based immunotherapy is influenced by many factors such as surgery, stage.

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

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

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

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

Phenotypic characterization and anticancer capacity of CD8+ cytokine-induced killer cells after antigen-induced expansion

Cytokine-induced killer cells (CIK) have been used in clinic for adoptive immunotherapy in a variety of malignant tumors and have improved the prognosis of cancer patients. However, there are individual differences in the CIK cell preparations including the obvious differences in the ratio of effector CIK cells among different cancer patients. Infusion of such heterogeneous immune cell preparation is an important factor that would affect the therapeutic efficacy. We report here the enrichment and expansion of CD8+ cells from CIK cells cultured for one week using magnetic activated cell sorting (MACS). These enriched CD8+ CIK cells expressed T cell marker CD3 and antigen recognition receptor NKG2D. Phenotypic analysis showed that CD8+ CIK cells contained 32.4% of CD3+ CD56+ natural killer (NK)-like T cells, 23.6% of CD45RO+ CD28+, and 50.5% of CD45RA+ CD27+ memory T cells. In vitro cytotoxic activity assay demonstrated that the enriched CD8+ CIK cells had significant cytotoxic activity against K562 cells and five ovarian cancer cell lines. Intriguingly, CD8+ CIK cells had strong cytotoxic activity against OVCAR3 cells that has weak binding capability to NKG2D. Flow cytometry and quantitative RT-PCR analysis revealed that OVCAR3 cells expressed HLA-I and OCT4 and Sox2, suggesting that CD8+ CIK cells recognize surface antigen via specific T cell receptor and effectively kill the target cells. The results suggest that transplantation of such in vitro enriched and expanded OCT4-specific CD8+ CIK cells may improve the specific immune defense mechanism against cancer stem cells, providing a novel avenue of cancer stem cell targeted immunotherapy for clinical treatment of ovarian cancer.

Role of NKG2D in cytokine-induced killer cells against lung cancer

It has been previously demonstrated that cytokine-induced killer (CIK) cells possess potent cytotoxicity against various cancer cells, including lung cancer cells. However, the mechanism by which CIK cells recognize lung cancer cells has not been understood. The interaction between killer cell lectin like receptor K1 (NKG2D) receptor and NKG2D ligands was demonstrated to serve an important role in target cell killing by natural killer cells. The present study investigated whether NKG2D receptor and NKG2D ligand interactions are involved in the CIK-directed killing of lung cancer cells. The expression of MICA and ULBP2 was detected in tumor and healthy tissue samples. The expression of MICA and ULBP2 in tumor tissue samples was higher compared with that in the healthy control tissue. The expression of NKG2D ligands was analyzed in A549 and Q56 cells through reverse transcription-quantitative polymerase chain reaction and flow cytometry. The results demonstrated that the lung cancer cell lines markedly expressed the NKG2D ligands. Furthermore, NKG2D ligand-expressing lung cancer cells were targeted by CIK cells, which was partially blocked by treating CIK cells with an antibody against NKG2D. The data of the current study has demonstrated that the NKG2D-NKG2D ligand interaction serves an essential role in mediating lung cancer cell killing by CIK cells.

Cytokine-induced killer cells hunt individual cancer cells in droves in a mouse model

Cytotoxicity of cytokine-induced killer (CIK) cells depends mainly on their encounters with target cells, but how many CIK cells are required to kill an individual cancer cell is unknown. Here we used time-lapse imaging to quantify the critical effector cell number required to kill an individual target cell. CIK cells killed MHC-I-negative and MHC-I-positive cancer cells, but natural killer (NK) cells destroyed MHC-I-negative cells only. The average threshold number of CIK cells required to kill an individual cancer cell was 6.7 for MHC-I-negative cells and 6.9 for MHC-I-positive cells. That of NK cells was 2.4 for MHC-I-negative cells. Likely due to the higher threshold numbers, killing by CIK cells was delayed in comparison with NK cells: 40% of MHC-negative target cells were killed after 5 h when co-cultured with CIK cells and after 2 h with NK cells. Our data have implications for the rational design of CIK cell-based immunotherapy of cancer patients.

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.

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

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

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.

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

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

Immunoreceptor TIGIT inhibits the cytotoxicity of human cytokine-induced killer cells by interacting with CD155

T cell Ig and ITIM domain (TIGIT) is a newly identified inhibitory receptor expressed on T and natural killer (NK) cells. Cytokine-induced killer (CIK) cells express CD3 and CD56 molecules, and share functional properties with both NK and T cells. However, it remains unknown whether TIGIT is expressed in CIK cells. Here, we show that TIGIT is expressed by CIK cells and interacts with CD155. By blocking TIGIT using an anti-TIGIT functional antibody, we demonstrate that CIK cells display increased proliferation; higher cytotoxic targeting of tumor cells expressing CD155; and higher expression of interferon-γ (IFN-γ), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Furthermore, increases in IFN-γ and cytotoxicity by blockade of TIGIT were reduced by blocking DNAX accessory molecule-1 (DNAM-1) signaling, implying that TIGIT exerts immunosuppressive effects by competing with DNAM-1 for the same ligand, CD155. Our results provide evidence that blockade of TIGIT may be a novel strategy to improve the cytotoxic activity of CIK cells.

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

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

Cytokine-induced killer 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.

Adjuvant immunotherapy with autologous cytokine-induced killer cells for hepatocellular carcinoma

BACKGROUND & AIMS

No adjuvant therapy has been shown to extend the survival of patients with hepatocellular carcinoma (HCC) receiving curative treatment. We investigated whether injections of activated cytokine-induced killer (CIK) cells (CD3+/CD56+ and CD3+/CD56- T cells and CD3-/CD56+ natural killer cells) prolongs recurrence-free survival of patients after curative therapy for HCC.

METHODS

We performed a multicenter, randomized, open-label, phase 3 trial of the efficacy and safety of adjuvant immunotherapy with activated CIK cells (created by incubation of patients' peripheral blood mononuclear cells with interleukin 2 and an antibody against CD3). The study included 230 patients with HCC treated by surgical resection, radiofrequency ablation, or percutaneous ethanol injection at university-affiliated hospitals in Korea. Patients were assigned randomly to receive immunotherapy (injection of 6.4 × 10(9) autologous CIK cells, 16 times during 60 weeks) or no adjuvant therapy (controls). The primary end point was recurrence-free survival; secondary end points included overall survival, cancer-specific survival, and safety.

RESULTS

The median time of recurrence-free survival was 44.0 months in the immunotherapy group and 30.0 months in the control group (hazard ratio with immunotherapy, 0.63; 95% confidence interval [CI], 0.43-0.94; P = .010 by 1-sided log-rank test). Hazard ratios also were lower in the immunotherapy than in the control group for all-cause death (0.21; 95% CI, 0.06-0.75; P = .008) and cancer-related death (0.19; 95% CI, 0.04-0.87; P = .02). A significantly higher proportion of patients in the immunotherapy group than in the control group had an adverse event (62% vs 41%; P = .002), but the proportion of patients with serious adverse events did not differ significantly between groups (7.8% vs 3.5%; P = .15).

CONCLUSIONS

In patients who underwent curative treatment for HCC, adjuvant immunotherapy with activated CIK cells increased recurrence-free and overall survival. ClinicalTrials.gov number: NCT00699816.

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

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

Phenotypic characterization and anti-tumor effects of cytokine-induced killer cells derived from cord blood

BACKGROUND AIMS

Cytokine-induced killer (CIK) cell therapy represents a feasible immunotherapeutic option for treating malignancies. However, the number of anti-tumor lymphocytes cannot be easily obtained from the cancer patients with poor immunity status, and older patients cannot tolerate repeated collection of blood. Cord blood-derived CIK (CB-CIK) cells have shown efficacy in treating the patients with cancer in several clinical trials. This study was conducted to evaluate the biological characteristics and anti-tumor function of CB-CIK cells.

METHODS

The immunogenicity, chemokine receptors and proliferation of CB-CIK cells were analyzed by flow cytometry. The CIK cells on day 13 were treated with cisplatin and the anti-apoptosis capacity was analyzed. The function of CB-CIK cells against the human cancer was evaluated both in vitro and in vivo.

RESULTS

Compared with peripheral blood-derived CIK (PB-CIK) cells, CB-CIK cells demonstrated lower immunogenicity and increased proliferation rates. CB-CIK cells also had a higher percentage of main functional fraction CD3(+)CD56(+). The anti-apoptosis ability of CB-CIK cells after treatment with cisplatin was higher than that of PB-CIK cells. Furthermore, CB-CIK cells were effective for secreting interleukin-2 and interferon-γ and a higher percentage of chemokine receptors CCR6 and CCR7. In addition, tumor growth was greatly inhibited by CB-CIK treatment in a nude mouse xenograft model.

CONCLUSIONS

CB-CIK cells exhibit more efficient anti-tumor activity in in vitro analysis and in the preclinical model and may serve as a potential therapeutic approach for the treatment of cancer.

Cytokine-induced killer cells: A novel immunotherapy strategy for leukemia

Cytokine-induced killer (CIK) cells are NK-like T cells derived from peripheral blood mononuclear cells that are co-stimulated and expanded using cytokines for 14–21 days in vitro. CIK cells are a heterogeneous subset of highly-efficient cytotoxic T effector cells that mediate major histocompatibility complex-unrestricted cytotoxicity against a broad array of tumor cells. These effector cells are generated from patients with leukemia or healthy donors who demonstrate similar cytotoxic activity against leukemia blasts. Allogeneic CIK cells retain the ability to produce the graft versus tumor response and generate minimal graft versus host disease. In addition, CIK cells possess no cytotoxicity against normal hematopoietic stem cells in vivo. Leukemia recurrence remains a formidable obstacle, but adoptive immunotherapy offers promise for the eradication of minimal residual disease and prevention of leukemia relapse following hematopoietic stem cell transplantation. CIK cell infusion started a novel generation of adoptive immunotherapy and exhibits particular potential applications in the area of hematological malignancy. In the present study, the previous strategies of leukemia immunotherapy using CIK cells are reviewed and the future directions of development are discussed.

Enhancement of the cytotoxic activity of cytokine-induced killer cells transfected with IL3PE38KDEL gene against acute myeloid leukemia cells

Cytokine-induced killer (CIK) cells, one of the feasible and effective methods of adoptive immunotherapy, have shown anti-leukemia activity in vivo and in vitro. But the strategy exhibits limited cytotoxic activity in clinical studies. In this study, CIK cells were transfected with an interleukin-3/Pseudomonas exotoxin gene (IL3PE38KDEL). RT-PCR and ELISA were used to verify the expression of IL3PE38KDEL in the transfected CIK cells. These cells released 1,186.7 ± 149.6 pg IL3PE38KDEL/10(4) cells over 48 h into the medium and the culture supernatant selectively killed IL3 receptor(IL3R)-positive HL60 cells, but not IL3R-negative K562 cells. Moreover, IL3PE38KDEL transfection did not influence phenotypes and cytokine production of CIK cells. Co-cultured with leukemia cells, IL3PE38KDEL transfected CIK cells showed enhanced cytotoxicity against IL3R-positive HL60 cells at all effector-to-target (E:T) ratios, but exerted a basal anti-leukemia activity against IL3R-negative K562 cells. Our findings demonstrate that IL3PE38KDEL gene transfection may be a novel strategy for improving anti-leukemia activity of CIK cells.

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.

Homing of cytokine-induced killer cells during the treatment of acute promyelocytic leukemia

Cytokine-induced killer (CIK) cells have been shown to be an effective immunotherapy for malignancies. However, their clinical application has been limited due to lack of knowledge on their in vivo kinesis. In this study, we explored their biodistribution by labeling CIK cells with (18)F-FDG and tracking their in vivo migration by PET/CT imaging. In the nine refractory APL patients enrolled in this study, pre-treatment PET/CT scans revealed leukemia burdens in vertebrae, and the bones of the pelvis and limbs. Post-treatment serial PET/CT tracked the localization of CIK cells over time: at 1 h, the majority of these cells accumulated diffusely in the lungs, while the first minor cell activities were observed in brain, liver and spleen; at 4 and 8 h, they not only migrated to the heart, spleen, and liver, but also showed tendencies to accumulate in bone marrow and brain. This specific cell migration route suggested that CIK cells show in vivo functional kinesis and potency as a targeted immunotherapy. The clinical outcome of this small cohort of nine patients supported the efficacy of this regimen: two patients achieved rapid complete remission after three-cycle treatment, and six patients remained stable, subsequently became sensitive to conventional therapy, and also achieved complete remission.

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.

Chimeric antigen receptors against CD33/CD123 antigens efficiently target primary acute myeloid leukemia cells in vivo

As significant numbers of acute myeloid leukemia (AML) patients are still refractory to conventional therapies or experience relapse, immunotherapy using T cells expressing chimeric antigen receptors (CARs) might represent a valid treatment option. AML cells frequently overexpress the myeloid antigens CD33 and CD123, for which specific CARs can be generated. However, CD33 is also expressed on normal hematopoietic stem/progenitor cells (HSPCs), and its targeting could potentially impair normal hematopoiesis. In contrast, CD123 is widely expressed by AML, while low expression is detected on HSPCs, making it a much more attractive target. In this study we describe the in vivo efficacy and safety of using cytokine-induced killer (CIK) cells genetically modified to express anti-CD33 or anti-CD123 CAR to target AML. We show that both these modified T cells are very efficient in reducing leukemia burden in vivo, but only the anti-CD123 CAR has limited killing on normal HSPCs, thus making it a very attractive immunotherapeutic tool for AML treatment.