Dual-functional capability of CD3+CD56+ CIK cells, a T-cell subset that acquires NK function and retains TCR-mediated specific cytotoxicity. Blood. 2011;118:3301-3310. [PMID: 21821703 DOI: 10.1182/blood-2011-02-336321]

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.

Immunosuppressive tumor microenvironment in the progression, metastasis, and therapy of hepatocellular carcinoma: from bench to bedside

Hepatocellular carcinoma (HCC) is a highly heterogeneous malignancy with high incidence, recurrence, and metastasis rates. The emergence of immunotherapy has improved the treatment of advanced HCC, but problems such as drug resistance and immune-related adverse events still exist in clinical practice. The immunosuppressive tumor microenvironment (TME) of HCC restricts the efficacy of immunotherapy and is essential for HCC progression and metastasis. Therefore, it is necessary to elucidate the mechanisms behind immunosuppressive TME to develop and apply immunotherapy. This review systematically summarizes the pathogenesis of HCC, the formation of the highly heterogeneous TME, and the mechanisms by which the immunosuppressive TME accelerates HCC progression and metastasis. We also review the status of HCC immunotherapy and further discuss the existing challenges and potential therapeutic strategies targeting immunosuppressive TME. We hope to inspire optimizing and innovating immunotherapeutic strategies by comprehensively understanding the structure and function of immunosuppressive TME in HCC.

NK-like CD8 T cell: one potential evolutionary continuum between adaptive memory and innate immunity

CD8 T cells are crucial adaptive immune cells with cytotoxicity to fight against pathogens or abnormal self-cells via major histocompatibility complex class I-dependent priming pathways. The composition of the memory CD8 T-cell pool is influenced by various factors. Physiological aging, chronic viral infection, and autoimmune diseases promote the accumulation of CD8 T cells with highly differentiated memory phenotypes. Accumulating studies have shown that some of these memory CD8 T cells also exhibit innate-like cytotoxicity and upregulate the expression of receptors associated with natural killer (NK) cells. Further analysis shows that these NK-like CD8 T cells have transcriptional profiles of both NK and CD8 T cells, suggesting the transformation of CD8 T cells into NK cells. However, the specific induction mechanism underlying NK-like transformation and the implications of this process for CD8 T cells are still unclear. This review aimed to deduce the possible differentiation model of NK-like CD8 T cells, summarize the functions of major NK-cell receptors expressed on these cells, and provide a new perspective for exploring the role of these CD8 T cells in health and disease.

Multi‑omics approach to improve patient‑tailored therapy using immune checkpoint blockade and cytokine‑induced killer cell infusion in an elderly patient with lung cancer: A case report and literature review

The 5-year survival rate of patients with advanced non-small cell lung cancer (NSCLC) remains low, despite recent advances in targeted therapy and immunotherapy. Therefore, there is a need to identify alternative strategies to improve treatment outcomes. Modern diagnostics can significantly facilitate the selection of treatment plans to improve patient outcomes. In the present study, multi-form diagnostic methodologies were adopted, including next-generation sequencing-based actionable gene sequencing, programmed death ligand 1 (PD-L1) immunohistochemistry, a circulating tumor cell (CTC) assay, flow cytometric analysis of lymphocyte subsets and computed tomography, to improve disease management in an 86-year-old female patient with relapsed metastatic NSCLC. High expression of PD-L1, elevated CTC tmutations, were observed. Based on these results, the patient was initially treated with the programmed death protein 1 blocking antibody sintilimab for two cycles, resulting in the stabilization of their condition, although the patient still exhibited severe pain and other symptoms, including fatigue, malaise, a loss of appetite and poor mental state. Informed by dynamic monitoring of the patient's response to treatment, the treatment plan was subsequently adjusted to a combination therapy with sintilimab and autologous cytokine-induced killer cell infusion, which eventually led to improved outcomes in both the management of the cancer and quality of life. In conclusion, multi-omics analysis may be used to establish patient-tailored therapies to improve clinical outcomes in hard-to-treat elderly patients with metastatic NSCLC.

Evolving insights into the improvement of adoptive T-cell immunotherapy through PD-1/PD-L1 blockade in the clinical spectrum of lung cancer

Undeniably, cancer immunotherapies have expanded the spectrum of cancer treatment, however, some patients do not respond to immunotherapies. This scenario is no different for lung cancer, whose two main types, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), still pose a serious clinical challenge. Adoptive T-cell therapies (ATC), which primarily include cytokine-induced killer (CIK) cell therapy, chimeric antigen receptor T-cell (CAR T-cell) therapy and γδ-T-cell therapy, strengthen the patient's immune system in combating cancer. Combining ATC with immune checkpoint inhibitors (ICI) further enhances the effectiveness of this approach to eradicate cancer. With a particular emphasis on CIK cell therapy, which recently completed 30 years, we highlight the role of the PD-1/PD-L1 axis in NSCLC and SCLC. Besides, we provide insights into the potential synergies of PD-1/PD-L1 inhibitors with adoptive T-cell immunotherapy in reshaping the treatment paradigm for lung cancer.

CAR products from novel sources: a new avenue for the breakthrough in cancer immunotherapy

Chimeric antigen receptor (CAR) T cell therapy has transformed cancer immunotherapy. However, significant challenges limit its application beyond B cell-driven malignancies, including limited clinical efficacy, high toxicity, and complex autologous cell product manufacturing. Despite efforts to improve CAR T cell therapy outcomes, there is a growing interest in utilizing alternative immune cells to develop CAR cells. These immune cells offer several advantages, such as major histocompatibility complex (MHC)-independent function, tumor microenvironment (TME) modulation, and increased tissue infiltration capabilities. Currently, CAR products from various T cell subtypes, innate immune cells, hematopoietic progenitor cells, and even exosomes are being explored. These CAR products often show enhanced antitumor efficacy, diminished toxicity, and superior tumor penetration. With these benefits in mind, numerous clinical trials are underway to access the potential of these innovative CAR cells. This review aims to thoroughly examine the advantages, challenges, and existing insights on these new CAR products in cancer treatment.

Synergistic integration of histone deacetylase inhibitors apparently enhances the cytokine-induced killer cell efficiency in multiple myeloma via the NKG2D pathway

Objectives

The rapid recognition of epigenetic manipulation's potential in restricting cancer cell capabilities spurred translational initiatives, including histone deacetylase inhibitors (HDACis). Clinical trials on multiple myeloma (MM) demonstrated substantial benefits of HDACis, coupled with promising outcomes from cytokine-induced killer cell (CIK) immunotherapy. Intriguingly, the unexplored synergy of HDACis and CIK cell immunotherapy in MM prompted our study.

Methods

We examined clinically relevant HDACis (panobinostat/LBH589 and romidepsin) alongside CIK cells derived from peripheral blood mononuclear cells across diverse MM cell lines (U266, RPMI8226, OPM-2 and NCI-H929). Utilising various in vitro methodologies, we investigated how HDACis enhance CIK cell lysis of myeloma cells through NKG2D/NKG2D ligand interactions.

Results

The results of our analysis indicated several key findings. (1) Enhanced cytotoxicity of CIK cells in MM cells when combined with HDACis. (2) Significant increase in apoptosis, suggesting HDACis and CIK may together enhance apoptotic effects in specific MM cell lines. (3) Elevated IFN-γ secretion and alterations in granzyme B secretion because of the independent activity of HDACis. (4) Notably, HDACis increased the expression of MICA/B and ULBP2, crucial for inducing antitumor cytotoxicity of NKT cells. Validation through NKG2D receptor blocking in CIK cells with a purified mouse antihuman NKG2D antibody further supported our findings.

Conclusions

Our analyses provide sufficient evidence to consider this clinically forgotten instance (HDACis-CIK cell combination) as a therapeutic priority for MM treatment. Furthermore, we suggest that NKG2D/NKG2D-ligand interactions activating NK/NKT cells may contribute to enhanced myeloma cell lysis in response to HDACis treatment by CIK cells.

Generation and assessment of cytokine-induced killer cells for the treatment of colorectal cancer liver metastases

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. Cytokine-induced killer (CIK) cells are an adoptive immunotherapy reported to have strong anti-tumour activity across a range of cancers. They are a heterogeneous mix of lymphoid cells generated by culturing human peripheral blood mononuclear cells with cytokines and monoclonal antibodies in vitro. In this study, we investigated the yield and function of CIK cells generated from patients with CRC liver metastases. We first showed that CIK cells generated in serum free medium X-VIVO 15 were comparable to those from RPMI medium with 10% FBS in terms of the number and percentages of the main subsets of cells in the CIK culture, and the intracellular levels of granzyme B and perforin, and the pro-inflammatory cytokines IL-2, IFN-γ and TNF-α. The CIK cells were cytotoxic to CRC cell lines grown in 2D cultures or as spheroids, and against autologous patient-derived tumour organoids. Donor attributes such as age, sex, or prior chemotherapy exposure had no significant impact on CIK cell numbers or function. These results suggest that functional CIK cells can be generated from patients with CRC liver metastatic disease, and support further investigations into the therapeutic application of autologous CIK cells in the management of patients with CRC liver metastases.

Clinical application of cytokine-induced killer (CIK) cell therapy in colorectal cancer: Current strategies and future challenges

Colorectal cancer (CRC) remains a significant global health burden and is the second leading cause of cancer-related death. Cytokine induced killer (CIK) cell therapy is an immunotherapy which has the potential to meet this need. Clinical trials of CIK cell therapy for the management of CRC have reported improved clinical outcomes. However, production and delivery protocols varied significantly, and many studies were reported only in Chinese language journals. Here we present the most comprehensive review of the clinical CIK cell therapy trials for CRC management to date. We accessed both English and Chinese language clinical studies, and summarise how CIK cell therapy has been implemented, from manufacturing to patient delivery. We discuss current challenges that impede wider adoption of CIK cell therapy in CRC management.

The paths and challenges of "off-the-shelf" CAR-T cell therapy: An overview of clinical trials

The advent of chimeric antigen receptor T cells (CAR-T cells) has made a tremendous revolution in the era of cancer immunotherapy, so that since 2017 eight CAR-T cell products have been granted marketing authorization. All of these approved products are generated from autologous sources, but this strategy faces several challenges such as time-consuming and expensive manufacturing process and reduced anti-tumor potency of patients' T cells due to the disease or previous therapies. The use of an allogeneic source can overcome these issues and provide an industrial, scalable, and standardized manufacturing process that reduces costs and provides faster treatment for patients. Nevertheless, for using allogeneic CAR-T cells, we are faced with the challenge of overcoming two formidable impediments: severe life-threatening graft-versus-host-disease (GvHD) caused by allogeneic CAR-T cells, and allorejection of allogeneic CAR-T cells by host immune cells which is called "host versus graft" (HvG). In this study, we reviewed recent registered clinical trials of allogeneic CAR-T cell therapy to analyze different approaches to achieve a safe and efficacious "off-the-shelf" source for chimeric antigen receptor (CAR) based immunotherapy.

Adoptive cell therapy in paediatric extracranial solid tumours: current approaches and future challenges

Immunotherapy has ignited hope to cure paediatric solid tumours that resist traditional therapies. Among the most promising methods is adoptive cell therapy (ACT). Particularly, ACT using T cells equipped with chimeric antigen receptors (CARs) has moved into the spotlight in clinical studies. However, the efficacy of ACT is challenged by ACT-intrinsic factors, like lack of activation or T cell exhaustion, as well as immune evasion strategies of paediatric solid tumours, such as their highly immunosuppressive microenvironment. Novel strategies, including ACT using innate-like lymphocytes, innovative cell engineering techniques, and ACT combination therapies, are being developed and will be crucial to overcome these challenges. Here, we discuss the main classes of ACT for the treatment of paediatric extracranial solid tumours, reflect on the available preclinical and clinical evidence supporting promising strategies, and address the challenges that ACT is still facing. Ultimately, we highlight state-of-the-art developments and opportunities for new therapeutic options, which hold great potential for improving outcomes in this challenging patient population.

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.

The effect of serum origin on cytokines induced killer cell expansion and function

BACKGROUND

Cytokine-induced killer (CIK) cells have shown promising results in adoptive immunotherapy. However, serum may play a determining role in the large-scale expansion of these cells for clinical applications. According to Good Manufacturing Practice (GMP) guidelines to reduce the use of animal products in cell-based therapies; therefore, this study sought to investigate the impact of serum origin and the reduced serum concentration on the pattern of cell expansion and function.

METHODS

Peripheral blood mononuclear cells (PBMCs) isolated from a healthy donor were expanded based on the CIK cell expansion protocol. The cell culture medium was supplemented with three types of sera comprising fetal bovine serum (FBS), human serum (HS), or human-derived platelet lysate (hPL) at different concentrations (10%, 5%, and 2.5%). The proliferation kinetics for each group were investigated for 30 days of cell culture.

RESULTS

Cell proliferation in 10% concentration of all sera (hPL, FBS, HS) was higher than their lower concentrations. Moreover, hPL was significantly associated with higher expansion rates than FBS and HS in all three concentrations. Furthermore, cells cultured in hPL showed higher viability, cytotoxicity effect, and CIK CD markers expression.

CONCLUSION

hPL at a concentration of 10% showed the best effect on CIK cell proliferation and function.

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.

Prognostic factors and impact of CMV reactivation on acute myeloid leukemia patients after HLA-matched myeloablative allogeneic stem cell transplantation in a high CMV prevalence country

INTRODUCTION

Relapse of acute myeloid leukemia (AML) after allogeneic stem cell transplantation (allo-SCT) leads to dismal outcomes. This study aimed to identify high-risk patients and explore the effects of cytomegalovirus (CMV) reactivation in a high CMV-seropositive population.

METHODS

The study involved a single-center retrospective cohort in Thailand, analyzing clinical risk factors and CMV-mediated immune responses, correlated with transplant outcomes in AML patients.

RESULTS

Eighty-five patients with AML in complete remission (CR) undergoing HLA-matched myeloablative allo-SCT between 2011 and February 2021 were enrolled. The relapse rate was 27.1% with the median time of 7 months after transplantation. The 3-year relapse-free-survival (RFS) and overall-survival (OS) were 72.2% and 80.8%, respectively. The disease status (>CR1) and absence of chronic graft-versus-host disease (cGVHD) were independently significant adverse prognostic factors of RFS and OS. Ninety-two percent of recipient-donor pairs were both CMV seropositive. The CMV reactivation occurred in 54.1% of the patients. The clinically significant CMV infection rate was 49.4%. No CMV syndrome/disease or CMV-related mortality occurred. One-year cumulative incidence of relapse among CMV-reactivation and non-reactivation groups were 14.3% and 25.6%, respectively, without a statistically significant difference. Transplantation-related mortality was 11.1%.

CONCLUSIONS

The transplantation beyond CR1 and absence of cGVHD are powerful prognostic factors associated with inferior RFS and OS. In a high CMV prevalence country, there appears to be no impact of CMV reactivation on relapse in AML patients undergoing an allo-SCT.

Use of cytokine-induced killer cell therapy in patients with colorectal cancer: a systematic review and meta-analysis

BACKGROUND

The number of clinical studies evaluating the benefit of cytokine-induced killer cell (CIK) therapy, an adoptive immunotherapy, for colorectal cancer (CRC) is increasing. In many of these trials, CIK therapy was coadministered with conventional cancer therapy. The aim of this review is to systematically assess the available literature, in which the majority were only in Chinese, on CIK therapy for the management of CRC using meta-analysis and to identify parameters associated with successful CIK therapy implementation.

METHODS

Prospective and retrospective clinical studies which compared CIK therapy to non-CIK therapy in patients with CRC were searched for electronically on MEDLINE, Embase, China National Knowledge Infrastructure, and Wanfang Data databases. The clinical endpoints of overall survival (OS), progression-free survival (PFS), OS and PFS rates, overall response rate (ORR), and toxicity were meta-analyzed using HR and relative ratio (RR), and subgroup analyses were performed using chi-square (χ2) test and I-squared (I2) statistics for study design, disease stage, cotherapy type, and timing of administration.

RESULTS

In total, 70 studies involving 6743 patients were analyzed. CIK therapy was favored over non-CIK therapy for OS (HR=0.59, 95% CI: 0.53 to 0.65), PFS (HR=0.55, 95% CI: 0.47 to 0.63), and ORR (RR=0.65, 95% CI: 0.57 to 0.74) without increasing toxicity (HR=0.59, 95% CI: 0.16 to 2.25). Subgroup analyses on OS and PFS by study design (randomized vs non-randomized study design), disease stage (Stage I-III vs Stage IV), cotreatment with dendritic cells (DCs) (CIK vs DC-CIK therapy), or timing of therapy administration (concurrent vs sequential with coadministered anticancer therapy) also showed that the clinical benefit of CIK therapy was robust in any subgroup analysis. Furthermore, cotreatment with DCs did not improve clinical outcomes over CIK therapy alone.

CONCLUSION

Compared with standard therapy, patients who received additional CIK cell therapy had favorable outcomes without increased toxicity, warranting further investigation into CIK therapy for the treatment of CRC.

Harnessing novel strategies and cell types to overcome immune tolerance during adoptive cell therapy in cancer

Cell therapy encompasses an expanding spectrum of cell-based regimes for the treatment of human ailments, such as the use of immune cells, in particular T cells, for combating tumors and the modulation of inflammatory immune responses. In this review, we focus on cell therapy in the immuno-oncology space, which is largely driven by interests and demands from the clinics for better solutions to target various hard-to-treat cancers. We discuss recent advances in various types of cell therapies, including T cell receptor-T cells, chimeric antigen receptor (CAR)-T cells, tumor-infiltrating lymphocytes and natural killer cells. Particularly, the present review focuses on the strategies to improve therapeutic responses by either enhancing tumor recognition or the resilience of infused immune cells within tumor microenvironment. Finally, we discuss the potential of other innate or innate-like immune cell types currently being explored as promising CAR-cell alternatives that seek to address the limitations of conventional adoptive cell therapies.

Comparison of cytotoxic potency between freshly cultured and freshly thawed cytokine-induced killer cells from human umbilical cord blood

Immune cell therapy has been incorporated into cancer therapy over the past few years. Chimeric antigen receptor T cells (Car-T cells) transplantation is a novel and promising therapy for cancer treatment and introduces a new age of immune cell therapy. However, the expensive nature of genetic modification procedures limits the accessibility of Car-T cells for cancer treatment. Cytokine-induced killer cells (CIKs) can kill the target cells in an MHC-non-restricted manner; these cells can be developed to "off-the-shelf" immune cell products for cancer treatment. However, the anti-tumor potency of freshly thawed CIKs is not well documented. This study aimed to fill this gap, evaluating the anti-tumor potency of freshly thawed CIKs compared to that of freshly cultured CIKs. CIKs were produced from the human umbilical cord blood in accordance with published protocols. CIKs were cryopreserved in xeno-free cryomedium that contains 5% DMSO, 10% human serum in phosphate buffer saline at - 86 °C. These cells were thawed and immediately utilized in assays (called freshly thawed CIKs) with freshly cultured cells are control. The expression of the surface markers of CIKs, cytokine production, and in vitro anti-tumor cytotoxic cells of freshly thawed CIKs were evaluated and compared to freshly cultured CIKs. Additionally, the freshly thawed CIKs were injected into the breast of tumor-bearing mice to assess the anti-tumor potency in vivo. The results obtained in freshly thawed CIKs and freshly cultured CIKs demonstrated that the expression of CD3, and CD56 were comparable in both cases. The production of TNF-α, IFN-γ, and IL-10 was slightly reduced in freshly thawed cells compared to the freshly cultured cells. The in vitro lysis toward MCF-7 cancer cells was similar between freshly thawed and freshly cultured CIKs. Moreover, the freshly thawed CIKs displayed anti-breast tumor activity in the breast tumor-bearing mice. The volume of tumors significantly reduced in the mice grafted with freshly thawed CIKs while, conversely, the tumor volume in mice of the placebo group gradually increased. This study substantiated that freshly thawed CIKs preserved their anti-tumor potency in both in vitro and in vivo conditions. The results initially revealed the great potential of UCB-CIKs for "off-the-shelf" CIK product manufacturing. However, further studies on the effects of cryomedia, freezing rate, and thawing procedure should be undertaken before freshly thawed off-the-shelf UCB-CIKs are utilized in clinical trials.

Canine mammary carcinoma: current therapeutic targets and future perspectives – a review

Canine mammary carcinoma (CMC) is the most common neoplasm in bitches, and it shares many biological similarities with breast cancer in humans. Drug resistance, high epigenetic mutations, and relapse rates are among the challenges which eventually urge the need for a veterinary oncologist to discover new therapeutic approaches that are more effective and safer. Therefore, in this review, we also cover the current therapeutic strategies from human medicine for the future perspectives of tumor immunotherapy in veterinary medicine. These strategies have great potential to be employed as therapeutic or prophylactic options due to their ability to modulate a specific and potent immune response against CMC. As we acquire a better understanding of canine tumor immunology, we can move towards a brighter prognosis. Additionally, we report on the recent successful studies in breast cancer that may benefit canines as well.

Weaponizing natural killer cells for solid cancer immunotherapy

Enhancing natural killer (NK) cell-based innate immunity has become a promising strategy for immunotherapy against hard-to-cure solid cancers. Monoclonal antibody (mAb) therapy has been used to activate NK-cell-mediated antibody-dependent cellular cytotoxicity (ADCC) towards solid cancers. Cancer cells, however, can subvert immunosurveillance using multiple immunosuppressive mechanisms, which may hamper NK cell ADCC. Mechanisms to safely enhance ADCC by NK cells, such as utilizing temporary inhibition of receptor endocytosis to increase antibody presentation from target to effector cells can now be used to enhance NK-cell-mediated ADCC against solid tumors. This review summarizes and discusses the recent advances in the field and highlights current and potential future use of immunotherapies to maximize the therapeutic efficacy of innate anticancer immunity.

Role of NKT cells in cancer immunotherapy-from bench to bed

Natural killer T (NKT) cells are a specific T cell subset known to express the αβ-T cell receptor (TCR) for antigens identification and express typical NK cell specifications, such as surface expression of CD56 and CD16 markers as well as production of granzyme. Human NKT cells are divided into two subgroups based on their cytokine receptor and TCR repertoire. Both of them are CD1-restricted and recognize lipid antigens presented by CD1d molecules. Studies have demonstrated that these cells are essential in defense against malignancies. These cells secret proinflammatory and regulatory cytokines that stimulate or suppress immune system responses. In several murine tumor models, activation of type I NKT cells induces tumor rejection and inhibits metastasis's spread. However, type II NKT cells are associated with an inhibitory and regulatory function during tumor immune responses. Variant NKT cells may suppress tumor immunity via different mechanisms that require cross-talk with other immune-regulatory cells. NKT-like cells display high tumor-killing abilities against many tumor cells. In the recent decade, different studies have been performed based on the application of NKT-based immunotherapy for cancer therapy. Moreover, manipulation of NKT cells through administering autologous dendritic cell (DC) loaded with α-galactosylceramide (α-GalCer) and direct α-GalCer injection has also been tested. In this review, we described different subtypes of NKT cells, their function in the anti-tumor immune responses, and the application of NKT cells in cancer immunotherapy from bench to bed.

Cytokine-Induced Killer Cell Immunotherapy Combined With Gemcitabine Reduces Systemic Metastasis in Pancreatic Cancer: An Analysis Using Preclinical Adjuvant Therapy-Mimicking Pancreatic Cancer Xenograft Model

OBJECTIVES

To evaluate the efficacy and safety of cytokine-induced killer (CIK) cell therapy in pancreatic cancer.

METHODS

An orthotopic murine model of pancreatic cancer and adjuvant therapy-mimicking xenograft murine model that underwent splenectomy was created. Eighty mice were randomized into four groups: the control, gemcitabine alone, CIK alone, and CIK with gemcitabine groups. The tumor growth was monitored using bioluminescence imaging once weekly.

RESULTS

In the orthotopic murine model, the treatment groups showed a significantly longer survival than the control group (median: not reached vs 125.0 days; 95% confidence interval, 119.87-130.13; P = 0.04); however, the overall survival did not differ significantly among the treatment groups (P = 0.779). The metastatic recurrence rate and overall survival were also not significantly different among the groups in the adjuvant therapy-mimicking xenograft murine model (P = 0.497). However, the CIK and gemcitabine combination suppressed the metastatic recurrence effectively, with recurrence-free survival being significantly longer in the CIK with gemcitabine group than in the control group (median, 54 days; 95% confidence interval, 25.00-102.00; P = 0.013).

CONCLUSIONS

The combination of CIK and gemcitabine suppressed systemic metastatic recurrence, with promising efficacy and good tolerability in an adjuvant setting of pancreatic cancer.

Acute exercise mobilizes NKT-like cells with a cytotoxic transcriptomic profile but does not augment the potency of cytokine-induced killer (CIK) cells

CD3⁺/CD56⁺ Natural killer (NK) cell-like T-cells (NKT-like cells) represent <5% of blood lymphocytes, display a cytotoxic phenotype, and can kill various cancers. NKT-like cells can be expanded ex vivo into cytokine-induced killer (CIK) cells, however this therapeutic cell product has had mixed results against hematological malignancies in clinical trials. The aim of this study was to determine if NKT-like cells mobilized during acute cycling exercise could be used to generate more potent anti-tumor CIK cells from healthy donors. An acute exercise bout increased NKT-like cell numbers in blood 2-fold. Single cell RNA sequencing revealed that exercise mobilized NKT-like cells have an upregulation of genes and transcriptomic programs associated with enhanced anti-tumor activity, including cytotoxicity, cytokine responsiveness, and migration. Exercise, however, did not augment the ex vivo expansion of CIK cells or alter their surface phenotypes after 21-days of culture. CIK cells expanded at rest, during exercise (at 60% and 80% VO_2max) or after (1h post) were equally capable of killing leukemia, lymphoma, and multiple myeloma target cells with and without cytokine (IL-2) and antibody (OKT3) priming in vitro. We conclude that acute exercise in healthy donors mobilizes NKT-like cells with an upregulation of transcriptomic programs involved in anti-tumor activity, but does not augment the ex vivo expansion of CIK cells.

Novel IL-15 dendritic cells have a potent immunomodulatory effect in immunotherapy of multiple myeloma

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Culture DCs with GM-CSF + IL-4 + IL-15 (IL-15 DCs) can be shortened for 6 days.

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IL-15 DCs showed high expression levels of costimulatory receptors, IFN-γ and IL-12p70.

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IL-15 DCs showed strong stimulation toward T, CIK and NK cells.

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The activated lymphocytes showed high cytotoxicity against myeloma cells.

Dendritic cells (DCs) are the most potent antigen-presenting cells, and have thus been used in clinical cancer vaccines. However, the effects of DC vaccines are still limited, leading researchers to explore novel ways to make them effective. In this study, we investigated whether human monocyte-derived DCs generated via the addition of interleukin 15 (IL-15) had a higher capacity to induce antigen-specific T cells compared to conventional DCs. We isolated CD14⁺ monocytes from peripheral blood from multiple myeloma (MM) patients, and induced immature DCs with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 in the presence or absence of IL-15 for 4–6 days. Then we generated mature DCs (mDCs) with lipopolysaccharide for another 2 days [IL-15 mDCs (6 days), IL-15 mDCs (8 days), and conventional mDCs (8 days)]. IL-15 mDCs (6 days) showed higher expression of MHC I and II, CD40, CD86, and CCR7, and the secretion of IFN-γ was significantly higher compared to conventional mDCs. IL-15 mDCs (6 days) showed superior polarization of naïve T cells toward Th1 cells and a higher proportion of activated T cells, cytokine-induced killer (CIK) cells, and natural killer (NK) cells for inducing strong cytotoxicity against myeloma cells, and lower proportion of regulatory T cells compared to conventional mDCs. These data imply that novel multipotent mDCs generated by the addition of IL-15, which can be cultivated in 6 days, resulted in outstanding activation of T cells, CIK cells and NK cells, and may facilitate cellular immunotherapy for cancer patients.

Bystander T cells in cancer immunology and therapy

Cancer-specific T cells are required for effective anti-cancer immunity and have a central role in cancer immunotherapy. However, emerging evidence suggests that only a small fraction of tumor-infiltrating T cells are cancer specific, and T cells that recognize cancer-unrelated antigens (so-called 'bystanders') are abundant. Although the role of cancer-specific T cells in anti-cancer immunity has been well established, the implications of bystander T cells in tumors are only beginning to be understood. It is becoming increasingly clear that bystander T cells are not a homogeneous group of cells but, instead, they differ in their specificities, their activation states and effector functions. In this Perspective, we discuss recent studies of bystander T cells in tumors, including experimental and computational approaches that enable their identification and functional analysis and viewpoints on how these insights could be used to develop new therapeutic approaches for cancer immunotherapy.

The Hematology of Tomorrow Is Here-Preclinical Models Are Not: Cell Therapy for Hematological Malignancies

Simple Summary

Cell therapy is revolutionizing the prospect of deadly hematological malignancies such as high-risk acute myeloid leukemia. Stem cell therapy of allogeneic source from compatible human leukocyte antigen donor has exceptional success promoting durable remissions, but the rate of relapse is currently still high and there is transplant-related mortality. This review presents the current knowledge on the clinical use of mesenchymal stromal cells to improve outcomes in hematopoietic stem cell transplants. As an alternative or adjuvant approach to prevent relapse, we summarize the status of the promising forms of cellular immunotherapy aimed at targeting not only the bulk but also the cells of origin of leukemia. Finally, we discuss the available in vivo models for disease modelling and treatment efficacy prediction in these contexts.

Abstract

The purpose of this review is to present the current knowledge on the clinical use of several forms of cell therapy in hematological malignancies and the preclinical models available for their study. In the context of allogeneic hematopoietic stem cell transplants, mesenchymal stromal cells are pursued to help stem cell engraftment and expansion, and control graft versus host disease. We further summarize the status of promising forms of cellular immunotherapy including CAR T cell and CAR NK cell therapy aimed at eradicating the cells of origin of leukemia, i.e., leukemia stem cells. Updates on other forms of cellular immunotherapy, such as NK cells, CIK cells and CAR CIK cells, show encouraging results in AML. The considerations in available in vivo models for disease modelling and treatment efficacy prediction are discussed, with a particular focus on their strengths and weaknesses for the study of healthy and diseased hematopoietic stem cell reconstitution, graft versus host disease and immunotherapy. Despite current limitations, cell therapy is a rapidly evolving field that holds the promise of improved cure rates, soon. As a result, we may be witnessing the birth of the hematology of tomorrow. To further support its development, improved preclinical models including humanized microenvironments in mice are urgently needed.

HIF-1α Is a Rational Target for Future Ovarian Cancer Therapies

Ovarian cancer is the eighth most commonly diagnosed cancer among women worldwide. Even with the development of novel drugs, nearly one-half of the patients with ovarian cancer die within five years of diagnosis. These situations indicate the need for novel therapeutic agents for ovarian cancer. Increasing evidence has shown that hypoxia-inducible factor-1α(HIF-1α) plays an important role in promoting malignant cell chemoresistance, tumour metastasis, angiogenesis, immunosuppression and intercellular interactions. The unique microenvironment, crosstalk and/or interaction between cells and other characteristics of ovarian cancer can influence therapeutic efficiency or promote the disease progression. Inhibition of the expression or activity of HIF-1α can directly or indirectly enhance the therapeutic responsiveness of tumour cells. Therefore, it is reasonable to consider HIF-1α as a potential therapeutic target for ovarian cancer. In this paper, we summarize the latest research on the role of HIF-1α and molecules which can inhibit HIF-1α expression directly or indirectly in ovarian cancer, and drug clinical trials about the HIF-1α inhibitors in ovarian cancer or other solid malignant tumours.

Recent advances in immunotherapy for hepatocellular carcinoma

BACKGROUND

Treatment of hepatocellular carcinoma (HCC) is challenging as most patients are diagnosed at advanced stage with underlying chronic liver conditions. Conventional systemic chemotherapy has failed in HCC, and the clinical efficacy of FDA-approved molecular targeted agents such as sorafenib and lenvatinib remains unsatisfactory.

DATA SOURCES

Literature search was conducted in PubMed for relevant articles published before January 2021. The search aimed to identify recent developments in immune-based treatment approaches for HCC. Information of clinical trials was obtained from https://clinicaltrials.gov/.

RESULTS

Two immune checkpoint inhibitors (ICIs), nivolumab and pembrolizumab were approved as monotherapies, which has revolutionized HCC treatment. Besides, combination ICIs have also got accelerated FDA approval recently. Immune-based therapies have challenged targeted drugs owing to their safety, tolerability, and survival benefits. In addition to the significant success in ICIs, other immunotherapeutic strategies such as cancer vaccine, chimeric antigen receptor T-cells, natural killer cells, cytokines, and combination therapy, have also shown promising outcomes in clinical trials. Various diagnostic and prognostic biomarkers have been identified which can help in clinical decision making when starting treatment with ICIs.

CONCLUSIONS

Immunotherapy has emerged as one of the mainstream treatment modalities for advanced HCC in recent years. However, challenges such as low response rate and acquired resistance in previously respondent patients still exist. Further research is needed to understand the unique resistance mechanism to immunotherapy and to discover more predictive biomarkers to guide clinical decision making.

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.

Innovative therapeutic strategy for B-cell malignancies that combines obinutuzumab and cytokine-induced killer cells

Background

Patients affected by aggressive B-cell malignancies who are resistant to primary or salvage chemoimmunotherapy have an extremely poor prognosis and limited therapeutic options. Promising therapeutic success has been achieved with the infusion of CD19 chimeric antigen receptor-T cells, but several limits still restrain the administration to a limited proportion of patients. This unmet clinical need might be fulfilled by an adoptive immunotherapy approach that combines cytokine-induced killer (CIK) cells and monoclonal antibodies (mAb) to the CD20 antigen. Indeed, CIK cells are an effector population endowed with antitumor activity, which can be further improved and antigen-specifically redirected by clinical-grade mAb triggering antibody-dependent cell-mediated cytotoxicity.

Methods

CIK cells were generated from peripheral blood of patients affected by different B-cell malignancies using a blinatumomab-based cell culture protocol. Effector cells were combined with the anti-CD20 mAb obinutuzumab and their therapeutic activity was assessed both in vitro and in vivo.

Results

CIK cells were successfully expanded in clinically relevant numbers, starting from small volumes of peripheral blood with extremely low CD3⁺ counts and high tumor burden. This relied on the addition of blinatumumab in culture, which leads to the simultaneous expansion of effector cells and the complete elimination of the neoplastic component. Moreover, CIK cells were highly cytotoxic in vitro against both B-cell tumor cell lines and autologous neoplastic targets, and had a significant therapeutic efficacy against a B-cell malignancy patient-derived xenograft on in vivo transfer.

Conclusions

The combination of an easily expandable CIK cell effector population with a mAb already in clinical use establishes a tumor antigen-specific redirection strategy that can be rapidly translated into clinical practice, providing an effective therapeutic alternative for B-cell malignancies without any need for genetic modifications. Additionally, the approach can be potentially applied to an extremely vast array of different tumors by simply substituting the targeting mAb.

The Crosstalk Between Dendritic Cells, Cytokine-Induced Killer Cells And Cancer Cells From The Perspective Of Combination Therapy

Dendritic cells (DCs) are considered the most potent professional antigen-presenting cells (APCs) that elicit adaptive antitumour immunity. DCs integrate multiple environmental signals by efficiently processing tumour-associated antigens (TAAs) and migrating to draining lymph nodes (dLNs), where they present foreign antigens to T cells for priming. DCs thus serve as a major link between innate and adaptive immunity. Although DCs (mostly monocyte-derived DCs [mo-DCs]) have already been used in cancer therapies, such approaches have shown limited efficacy. Mo-DCs have the unique ability to present antigens to T cells in peripheral tissues. CD3+CD56+ cytokine-induced killer (CIK) cells are characterized by both MHC-restricted and MHC-unrestricted antitumour cytotoxicity against a broad range of cancer cells. This review presents an overview of the mechanisms by which mo-DCs and CIK cells’ interact with each other and with tumours. The maturation of DCs was identified as a crucial step in the development of effective DC-based vaccines against cancer. A further improved adoptive immunotherapy strategy involves a combination of mature mo-DCs and CIK cells. Combination therapy presents many opportunities for cancer treatment, as reported by a number of clinical trials. However, there is a lack of fundamental studies on the interaction of in vitro-generated mo-DCs with CIK cells. We discuss several methods of boosting DC-based vaccines and review the current knowledge of contact-dependent and cytokine-induced interactions of mo-DCs with CIK cells. We highlight that the combination of mo-DCs with CIK cells activates MHC-restricted and MHC-unrestricted immune responses.

The effects of stereotactic body radiotherapy on peripheral natural killer and CD3+CD56+ NKT-like cells in patients with hepatocellular carcinoma

BACKGROUND

Both natural killer (NK) and CD3⁺CD56⁺natural killer T (NKT)-like cells play critical roles in the antitumor response. This study aimed to explore the effects of stereotactic body radiotherapy (SBRT) on peripheral NK and NKT-like cells in patients with hepatocellular carcinoma (HCC), and to identify possible surface markers on these cells that correlate with the prognosis.

METHODS

Twenty-five HCC patients were prospectively enrolled in our study, and 10 healthy individuals were served as healthy controls. Flow cytometry was used to determine the counts and the percentages of peripheral NK and NKT-like cells, cells with certain receptors, and cells with intracellular interferon-γ and TNF-α secretion at different time points, including time points of prior to SBRT, at post-SBRT, and 3-month and 6-month after treatment. The Kaplan-Meier method with the log-rank test was applied for survival analysis.

RESULTS

The peripheral NKT-like cells was increased at post-SBRT. Meanwhile, elevated levels of inhibitory receptors and reduced levels of activating receptors of NK cells were also observed in NK cells at post-SBRT, but the levels was not significantly different at 3-month and 6-month as compared with the baseline levels. Lower percentage of NKp30⁺NK cells before SBRT and higher percentage of CD158b⁺NK cells after SBRT were associated with poor progression-free survival. In addition, higher percentage of CD3⁺CD56⁺ NKT-like cells was associated with a higher overall survival rate in HCC patients.

CONCLUSIONS

SBRT has an apparent effect on both peripheral NK and CD3⁺CD56⁺NKT-like cells. Lower percentage of NKp30⁺NK cells before SBRT and higher percentage of CD158b⁺NK cells after SBRT are correlated with poor patients' PFS. Higher percentage of CD3⁺CD56⁺ NKT-like cells is associated with higher OS in HCC patients.

Advanced Renal-Cell Carcinoma Pseudoprogression After Combined Immunotherapy: Case Report and Literature Review

Treatment with a combination of programmed cell death-1 (PD-1) blocker and cytokine-induced killer (CIK) cells has improved outcome in cancer patients but is also associated with various patterns of responses. Pseudoprogression is a unique and uncommon phenomenon with no clear criteria for rapid diagnosis. Although some reports of pseudoprogression during immunotherapy exist, there are few reports of pseudoprogression occurring twice in the same patient. Here, we report the case of 51-year-old female patient with advanced renal cell carcinoma, who received a combination treatment of PD-1 blocker and CIK cells, and where pseudoprogression of lung and brain tumors occurred successively during treatment.

Next-generation cell therapies: the emerging role of CAR-NK cells

T cells engineered with chimeric antigen receptors (CARs) have revolutionized the field of cell therapy and changed the paradigm of treatment for many patients with relapsed or refractory B-cell malignancies. Despite this progress, there are limitations to CAR-T cell therapy in both the autologous and allogeneic settings, including practical, logistical, and toxicity issues. Given these concerns, there is a rapidly growing interest in natural killer cells as alternative vehicles for CAR engineering, given their unique biological features and their established safety profile in the allogeneic setting. Other immune effector cells, such as invariant natural killer T cells, γδ T cells, and macrophages, are attracting interest as well and eventually may be added to the repertoire of engineered cell therapies against cancer. The pace of these developments will undoubtedly benefit from multiple innovative technologies, such as the CRISPR-Cas gene editing system, which offers great potential to enhance the natural ability of immune effector cells to eliminate refractory cancers.

Cytokine-induced killer cells-assisted tumor-targeting delivery of Her-2 monoclonal antibody-conjugated gold nanostars with NIR photosensitizer for enhanced therapy of cancer

Maximizing the accumulation of anticancer medicine in the tumor is the priority to achieve minimal invasive cancer therapy, which raises high demands on tumor-targeting ability of drug delivery systems. Herein, we adopted an emerging "cell-drug" strategy via the nanoplatform construction to achieve high aggregation and intratumoral distribution. We fabricated gold nanostars (GNSs) with HER-2 monoclonal antibody (trastuzumab) and near-infrared region (NIR) photosensitizer indocyanine green (ICG) to obtain GNS@ICG-Ab, which combined the photothermal therapy with photodynamic therapy (PTT/PDT) that rely on enhanced photothermal conversion efficiency of GNS and 1O2 generator ICG under the exposure of a NIR laser. Tumor-tropism CIK cells loaded with GNS@ICG-Ab were able to migrate into tumors and make a difference in efficient accumulation and uniform distribution of the GNS@ICG-Ab-CIK nanoplatform inside tumors based on fluorescence, photoacoustic (PA), and computed tomography (CT) imaging observations. Encouraged by the improvements in tumor targeting and retention presented by real-time imaging, we employed the novel nanoplatform to synergistically inhibit the progression of tumors in SK-BR-3 tumor-bearing mice via PTT/PDT and immunotherapy-implemented by CIK cells for activating the immune response, and with the specific linkage between trastuzumab and SK-BR-3 tumor cells, our platform could exert a precise strike of PDT/PTT. Taken together, the integrating tri-modal imaging with tri-modal therapy endows CIK-GNS@ICG-Ab with promising potential in cancer theranostics and lays a solid foundation for the development of immune cell application in nanomedicine delivery.

Arming Immune Cells for Battle: A Brief Journey through the Advancements of T and NK Cell Immunotherapy

Simple Summary

This review is intended to provide an overview on the history and recent advances of T cell and natural killer (NK) cell-based immunotherapy. While the thymus was discovered as the origin of T cells in the 1960s, and NK cells were first described in 1975, the clinical application of adoptive cell therapies (ACT) only began in the early 1980s with the first lymphokine activated killer (LAK) cell product for the treatment of cancer patients. Over the past decades, further immunotherapies have been developed, including ACT using cytokine-induced killer (CIK) cells, products based on the NK cell line NK-92 as well as specific T and NK cell preparations. Recent advances have successfully improved the effectiveness of T, NK, CIK or NK-92 cells towards tumor-targeting antigens generated by genetic engineering of the immune cells. Herein, we summarize the promising development of ACT over the past decades in the fight against cancer.

Abstract

The promising development of adoptive immunotherapy over the last four decades has revealed numerous therapeutic approaches in which dedicated immune cells are modified and administered to eliminate malignant cells. Starting in the early 1980s, lymphokine activated killer (LAK) cells were the first ex vivo generated NK cell-enriched products utilized for adoptive immunotherapy. Over the past decades, various immunotherapies have been developed, including cytokine-induced killer (CIK) cells, as a peripheral blood mononuclear cells (PBMCs)-based therapeutic product, the adoptive transfer of specific T and NK cell products, and the NK cell line NK-92. In addition to allogeneic NK cells, NK-92 cell products represent a possible “off-the-shelf” therapeutic concept. Recent approaches have successfully enhanced the specificity and cytotoxicity of T, NK, CIK or NK-92 cells towards tumor-specific or associated target antigens generated by genetic engineering of the immune cells, e.g., to express a chimeric antigen receptor (CAR). Here, we will look into the history and recent developments of T and NK cell-based immunotherapy.

Next-generation cell therapies: the emerging role of CAR-NK cells

T cells engineered with chimeric antigen receptors (CARs) have revolutionized the field of cell therapy and changed the paradigm of treatment for many patients with relapsed or refractory B-cell malignancies. Despite this progress, there are limitations to CAR-T cell therapy in both the autologous and allogeneic settings, including practical, logistical, and toxicity issues. Given these concerns, there is a rapidly growing interest in natural killer cells as alternative vehicles for CAR engineering, given their unique biological features and their established safety profile in the allogeneic setting. Other immune effector cells, such as invariant natural killer T cells, γδ T cells, and macrophages, are attracting interest as well and eventually may be added to the repertoire of engineered cell therapies against cancer. The pace of these developments will undoubtedly benefit from multiple innovative technologies, such as the CRISPR-Cas gene editing system, which offers great potential to enhance the natural ability of immune effector cells to eliminate refractory cancers.

ERBB2-CAR-Engineered Cytokine-Induced Killer Cells Exhibit Both CAR-Mediated and Innate Immunity Against High-Risk Rhabdomyosarcoma

High-risk rhabdomyosarcoma (RMS) occurring in childhood to young adulthood is associated with a poor prognosis; especially children above the age of 10 with advanced stage alveolar RMS still succumb to the disease within a median of 2 years. The advent of chimeric antigen receptor (CAR)-engineered T cells marked significant progress in the treatment of refractory B cell malignancies, but experience for solid tumors has proven challenging. We speculate that this is at least in part due to the poor quality of the patient's own T cells and therefore propose using CAR-modified cytokine-induced killer (CIK) cells as effector cells. CIK cells are a heterogeneous population of polyclonal T cells that acquire phenotypic and cytotoxic properties of natural killer (NK) cells through the cultivation process, becoming so-called T-NK cells. CIK cells can be genetically modified to express CARs. They are minimally alloreactive and can therefore be acquired from haploidentical first-degree relatives. Here, we explored the potential of ERBB2-CAR-modified random-donor CIK cells as a treatment for RMS in xenotolerant mice bearing disseminated high-risk RMS tumors. In otherwise untreated mice, RMS tumors engrafted 13-35 days after intravenous tumor cell injection, as shown by in vivo bioluminescence imaging, immunohistochemistry, and polymerase chain reaction for human gDNA, and mice died shortly thereafter (median/range: 62/56-66 days, n = 5). Wild-type (WT) CIK cells given at an early stage delayed and eliminated RMS engraftment in 4 of 6 (67%) mice, while ERBB2-CAR CIK cells inhibited initial tumor load in 8 of 8 (100%) mice. WT CIK cells were detectable but not as active as CAR CIK cells at distant tumor sites. CIK cell therapies during advanced RMS delayed but did not inhibit tumor progression compared to untreated controls. ERBB2-CAR CIK cell therapy also supported innate immunity as evidenced by selective accumulation of NK and T-NK cell subpopulations in disseminated RMS tumors, which was not observed for WT CIK cells. Our data underscore the power of heterogenous immune cell populations (T, NK, and T-NK cells) to control solid tumors, which can be further enhanced with CARs, suggesting ERBB2-CAR CIK cells as a potential treatment for high-risk RMS.

Immunotherapy for advanced hepatocellular carcinoma, where are we?

A couple of molecular-targeting medications, such as Lenvatinib, are available for the treatment of hepatocellular carcinoma (HCC) in addition to Sorafenib in an advanced stage. Approval for the use of immune check-point inhibitors, such as Nivolumab and Pembrolizumab has shifted the paradigm of current HCC treatment, and the monotherapy or in combination with Lenvatinib or Sorafenib has significantly extended overall survival or progression-free survival in a large portion of patients. A combination of programmed cell death ligand-1 (PD-L1) inhibitor Atezolizumab with a vascular endothelial growth factor (VEGF) inhibitor, Bevacizumab, has recently achieved promising outcome in unresectable HCC patients. Other immunotherapy, such as chimeric antigen receptor T (CAR-T) cell therapy has achieved an evolutional success in hematologic malignancies, and has extended its use in deadly solid tumors, such as HCC. Although there exist various barriers, novel approaches are developed to move potential adoptive T cell therapy strategies, including cytokine-induced killer (CIK) cells, tumor-infiltrating lymphocytes (TIL), T cell receptor (TCR) T cells, CAR-T cells, to clinical application.

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.

Adoptive cell therapy of triple negative breast cancer with redirected cytokine-induced killer cells

Cytokine-Induced Killer (CIK) cells share several functional and phenotypical properties of both T and natural killer (NK) cells. They represent an attractive approach for cell-based immunotherapy, as they do not require antigen-specific priming for tumor cell recognition, and can be rapidly expanded in vitro. Their relevant expression of FcγRIIIa (CD16a) can be exploited in combination with clinical-grade monoclonal antibodies (mAbs) to redirect their lytic activity in an antigen-specific manner. Here, we report the efficacy of this combined approach against triple negative breast cancer (TNBC), an aggressive tumor that still requires therapeutic options. Different primitive and metastatic TNBC cancer mouse models were established in NSG mice, either by implanting patient-derived TNBC samples or injecting MDA-MB-231 cells orthotopically or intravenously. The combined treatment consisted in the repeated intratumoral or intravenous injection of CIK cells and cetuximab. Tumor growth and metastasis were monitored by bioluminescence or immunohistochemistry, and survival was recorded. CIK cells plus cetuximab significantly restrained primitive tumor growth in mice, either in patient-derived tumor xenografts or MDA-MB-231 cell line models. Moreover, this approach almost completely abolished metastasis spreading and dramatically improved survival. The antigen-specific mAb favored tumor and metastasis tissue infiltration by CIK cells, and led to an enrichment of the CD16a⁺ subset.

Data highlight the potentiality of this novel immunotherapy strategy where a nonspecific cytotoxic cell population can be converted into tumor-specific effectors with clinical-grade antibodies, thus providing not only a therapeutic option for TNBC but also a valid alternative to more complex approaches based on chimeric antigen receptor-engineered cells.

List of abbreviations

ACT, Adoptive Cell Transfer; ADCC, Antibody-Dependent Cell-mediated Cytotoxicity; ADP, Adenosine diphosphate; BLI, Bioluminescence Imaging; CAR, Chimeric Antigen Receptor; CIK, Cytokine Induced Killer cells; CTX, Cetuximab; DMEM, Dulbecco’s Modified Eagle Medium; EGFR, Human Epidermal Growth Factor 1; ER, Estrogen; FBS, Fetal Bovine Serum; FFPE, Formalin-Fixed Paraffin-Embedded; GMP, Good Manufacturing Practices; GVHD, Graft Versus Host Disease; HER2, Human Epidermal Growth Factor 2; HRP, Horseradish Peroxidase; IFN-γ, Interferon-γ; IHC, Immunohistochemistry; IL-2, Interleukin-2; ISO, Irrelevant antibody; i.t., intratumoral; i.v., intravenous, mAbs, Monoclonal Antibodies; mIHC, Multiplex Fluorescence Immunohistochemistry; MHC, Major Histocompatibility Complex; NK, Natural Killer; NKG2D, Natural-Killer group 2 member D; NSG, NOD/SCID common γ chain knockout; PARP, Poly ADP-ribose polymerase; PBMCs, Peripheral Blood Mononuclear Cells; PBS, Phosphate-buffered saline; PDX, Patient-derived xenograft; PR, Progesterone; rhIFN-γ, Recombinant Human Interferon-γ; RPMI, Roswell Park Memorial Institute; STR, Short tandem Repeat; TCR, T Cell Receptor; TNBC, Triple Negative Breast Cancer; TSA, Tyramide Signal Amplification

Targeting the "PVR-TIGIT axis" with immune checkpoint therapies

Checkpoint inhibitors have become an efficient way to treat cancers. Indeed, anti-CTLA-4, anti-PD1, and anti-PDL-1 antibodies are now used as therapies for cancers. However, while these therapies are very efficient in certain tumors, they remain poorly efficient in others. This might be explained by the immune infiltrate, the expression of target molecules, and the influence of the tumor microenvironment. It is therefore critical to identify checkpoint antigens that represent alternative targets for immunotherapies. PVR-like molecules play regulatory roles in immune cell functions. These proteins are expressed by different cell types and have been shown to be upregulated in various malignancies. PVR and Nectin-2 are expressed by tumor cells as well as myeloid cells, while TIGIT, CD96, and DNAM-1 are expressed on effector lymphoid cells. PVR is able to bind DNAM-1, CD96, and TIGIT, which results in two distinct profiles of effector cell activation. Indeed, while binding to DNAM-1 induces the release of cytokines and cytotoxicity of cytotoxic effector cells, binding TIGIT induces an immunosuppressive and non-cytotoxic profile. PVR is also able to bind CD96, which induces an immunosuppressive response in murine models. Unfortunately, in humans, results remain contradictory, and this interaction might induce the activation or the suppression of the immune response. Similarly, Nectin-2 was shown to bind TIGIT and to induce regulatory profiles in effectors cells such as NK and T cells. Therefore, these data highlight the potential of each of the molecules of the “PVR–TIGIT axis” as a potential target for immune checkpoint therapy. However, many questions remain to be answered to fully understand the mechanisms of this synapse, in particular for human CD96 and Nectin-2, which are still understudied. Here, we review the recent advances in “PVR–TIGIT axis” research and discuss the potential of targeting this axis by checkpoint immunotherapies.

Melanoma-associated fibroblasts impair CD8+ T cell function and modify expression of immune checkpoint regulators via increased arginase activity

Abstract

This study shows that melanoma-associated fibroblasts (MAFs) suppress cytotoxic T lymphocyte (CTL) activity and reveals a pivotal role played by arginase in this phenomenon. MAFs and normal dermal fibroblasts (DFs) were isolated from surgically resected melanomas and identified as Melan-A-/gp100-/FAP+ cells. CTLs of healthy blood donors were activated in the presence of MAF- and DF-conditioned media (CM). Markers of successful CTL activation, cytotoxic degranulation, killing activity and immune checkpoint regulation were evaluated by flow cytometry, ELISPOT, and redirected killing assays. Soluble mediators responsible for MAF-mediated effects were identified by ELISA, flow cytometry, inhibitor assays, and knock-in experiments. In the presence of MAF-CM, activated/non-naïve CTLs displayed dysregulated ERK1/2 and NF-κB signaling, impeded CD69 and granzyme B production, impaired killing activity, and upregulated expression of the negative immune checkpoint receptors TIGIT and BTLA. Compared to DFs, MAFs displayed increased amounts of VISTA and HVEM, a known ligand of BTLA on T cells, increased l-arginase activity and CXCL12 release. Transgenic arginase over-expression further increased, while selective arginase inhibition neutralized MAF-induced TIGIT and BTLA expression on CTLs. Our data indicate that MAF interfere with intracellular CTL signaling via soluble mediators leading to CTL anergy and modify immune checkpoint receptor availability via l-arginine depletion.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s00018-020-03517-8) contains supplementary material, which is available to authorized users.

Targeting prostate cancer stem-like cells by an immunotherapeutic platform based on immunogenic peptide-sensitized dendritic cells-cytokine-induced killer cells

Background

Autologous cellular immunotherapy or immune enhancement therapy has demonstrated some promising benefits for prostate cancer. T cell-based immunotherapy or sipuleucel-T therapy has yielded certain beneficial responses and a slight improvement on the overall survival of patients with metastatic castration-resistant prostate cancer (mCRPC) as shown in some clinical trials, suggesting that prostate cancer is immunoresponsive.

Methods

In this study, we developed an adaptive cytokine-induced killer cell (CIK)-based immunotherapeutic application targeting the prostate cancer stem-like cells (PCSCs). In this therapeutic platform, dendritic cells (DC) were isolated from the peripheral blood mononuclear cells (PBMCs) and preloaded or sensitized with immunogenic peptides derived from two PCSC-associated cell membrane molecules, CD44 and EpCAM, followed by co-culture with the expanded peripheral blood lymphocyte (PBL)-derived CIK cells. The in vitro cytotoxic activity of DC-activated CIK cells against PCSCs was determined by CCK8 and TUNEL assays, and the in vivo anti-tumor effect of DC-activated CIK cells on prostate cancer xenograft tumors was evaluated in subcutaneous and orthotopic xenograft models.

Results

Our results showed that the peptide-sensitized DC-CIK cell preparation manifested significant in vitro cytotoxic activity against the PCSC-enriched prostatospheroids and also in vivo anti-tumor effect against prostate cancer xenografts derived from the PCSC-enriched prostatospheroids.

Conclusions

Together, our established immunogenic peptide-sensitized DC-CIK-based cell preparation platform manifests its potential immunotherapeutic application in targeting the PCSCs and also prostate cancer.

LMP1-specific cytotoxic T cells for the treatment of EBV-related post-transplantation lymphoproliferative disorders

Epstein-Barr virus-specific cytotoxic T lymphocytes (EBV-CTLs) represent a promising treatment option for EBV-associated post-transplantation lymphoproliferative disorders (PTLD). However, production of EBV-CTLs is often complicated and expensive. In the present study, we sought to establish an easy-to-use and economical production protocol for EBV-CTLs. EBV-CTLs were generated using latent membrane protein 1 (LMP1) peptides based on a modified generation protocol of cytokine-induced killer (CIK) cells. After 2-week culture, cells were well expanded (median total cell number: 9.82 × 10⁹; median expansion fold: 107.8) and the median EBV LMP1-specific CD8⁺ T cell number was 8.94 × 10⁸ (median frequency: 6.7%). However, the EBV-CTL products, unlike CIK cells, did not exhibit NK-like anti-tumor activity. Furthermore, the clinical efficacy of EBV-CTLs was demonstrated with a successful treatment of PTLD on a compassionate use basis in a patient following haploidentical hematopoietic stem cell transplantation. This study indicates the safety and efficacy of EBV LMP1-specific CTLs generated based on a modified generation protocol of CIK cells. Further investigation in a well-designed clinical study is warranted.

Retrospective analysis of the efficacy of cytokine-induced killer cell immunotherapy combined with first-line chemotherapy in patients with metastatic colorectal cancer

Objectives

Fluoropyrimidine‐based chemotherapy regimens are the current first‐line treatment for metastatic colorectal cancer (mCRC); however, the outcome is often unsatisfactory. The present study aimed to determine the effect of combined cytokine‐induced killer (CIK) cell immunotherapy and first‐line chemotherapy in patients with mCRC.

Methods

This retrospective study included 252 patients with mCRC treated with first‐line chemotherapy. Among them, 126 patients received first‐line chemotherapy only (control group), while the other 126 patients, with similar demographic and clinical characteristics, received CIK cell immunotherapy combined with first‐line chemotherapy (CIK group). Overall survival (OS) and progression‐free survival (PFS) were compared between the two groups using the Kaplan–Meier method.

Results

The median OS for the CIK group was 54.7 versus 24.1 months for the controls, and the median PFS for the CIK group was 25.7 versus 14.6 months for the controls. Univariate and multivariate analyses indicated that CIK cell treatment was an independent prognostic factor for patients' OS and PFS. Subgroup analyses showed that CIK cell treatment significantly improved the OS and PFS of patients with metastatic colon cancer, but not those with metastatic rectal cancer. Additionally, the change in CD3⁺CD56⁺ subsets after the fourth treatment cycle might be an indicator of successful CIK cell treatment: Patients with increased CD3⁺CD56⁺ subsets had better survival than those with decreased CD3⁺CD56⁺ subsets.

Conclusion

Cytokine‐induced killer cell immunotherapy combined with first‐line chemotherapy could significantly improve the OS and PFS of patients with mCRC, particularly for patients with metastatic colon cancer.

Influence of major histocompatibility complex class I chain-related gene A polymorphisms on cytomegalovirus disease after allogeneic hematopoietic cell transplantation

OBJECTIVE/BACKGROUND

Cytomegalovirus (CMV) infection and disease are common infectious complications after allogeneic hematopoietic cell transplantation (alloHCT). Major histocompatibility complex (MHC) class I chain-related gene A (MICA) is a ligand of the natural killer (NKG2D) receptor on immune effector cells that helps mediate NK cell alloreactivity. We hypothesized that MICA polymorphisms may influence CMV infection and disease incidence after alloHCT.

METHODS

We conducted a retrospective analysis of 423 adults at the Cleveland Clinic with hematologic malignancies treated with a matched related or unrelated donor alloHCT. CMV cases analyzed included a compositive of instances of viral copy replication above detection limits as well as any biopsy-proven tissue invasive disease episodes. Genotypes at the MICA-129 position have been categorized as weak (valine/valine; V/V), intermediate (methionine/valine; M/V), or strong (methionine/methionine; M/M) receptor affinity.

RESULTS

In multivariable analysis, V/V donor MICA-129 genotype was associated with CMV infection and disease (hazard ratio [HR] = 1.40; 95% confidence interval [CI], 1.00-1.96; p = .05), but not MICA mismatch (HR = 1.38; 95% CI, 0.83-2.29; p = .22). There was no association of acute or chronic GVHD with MICA donor-recipient mismatch (HR = 1.05; 95% 95% CI, 0.66-1.68; p = .83 and HR = 0.94; 95% CI, 0.51-1.76; p = .85, respectively) or V/V donor MICA-129 genotypes (HR = 1.02; 95% CI, 0.79-1.31; p = .89 and HR = 0.89; 95% CI, 0.65-1.22; p = .47, respectively).

CONCLUSION

These findings suggest that the donor MICA-129 V/V genotype with weak NKG2D receptor binding affinity is associated with an increased risk of CMV infection and disease after alloHCT.

GD2-targeted chimeric antigen receptor T cells prevent metastasis formation by elimination of breast cancer stem-like cells

Expression of the disialoganglioside GD2 has been identified as a marker antigen associated with a breast cancer stem-like cell (BCSC) phenotype. Here, we report on the evaluation of GD2 as a BCSC-specific target antigen for immunotherapy. GD2 expression was confirmed at variable degree in a set of breast cancer cell lines, predominantly in triple-negative breast cancer (TNBC). To target GD2, we have generated novel anti-GD2 chimeric antigen receptors (GD2-CAR), based on single-chain variable fragments (scFv) derived from the monoclonal antibody (mAb) ch14.18, also known as dinutuximab beta. Expressed on T cells, GD2-CARs mediated specific GD2-dependent T-cell activation and target cell lysis. In contrast to previously described GD2-CARs, no signs of exhaustion by tonic signaling were found. Importantly, application of GD2-CAR expressing T cells (GD2-CAR-T) in an orthotopic xenograft model of TNBC (MDA-MB-231) halted local tumor progression and completely prevented lung metastasis formation. In line with the BCSC model, GD2 expression was only found in a subpopulation (4-6%) of MDA-MB-231 cells before injection. Significant expansion of GD2-CAR-T in tumor-bearing mice as well as T-cell infiltrates in the primary tumor and the lungs were found, indicating site-specific activation of GD2-CAR-T. Our data strongly support previous findings of GD2 as a BCSC-associated antigen. GD2-targeted immunotherapies have been extensively studied in human. In conclusion, GD2-CAR-T should be considered a promising novel approach for GD2-positive breast cancer, especially to eliminate disseminated tumor cells and prevent metastasis formation.

Antigen-independent killer cells prepared for adoptive immunotherapy: One source, divergent protocols, diverse nomenclature

Adoptive cell therapy (ACT) using tumor antigen-independent killer cells has been widely used in clinical trials of cancer treatment. Circumventing the need for identification of a particular tumor-associated antigen on tumor cells, the approach has opened possibilities for the extension of ACT immunotherapy to patients with a wide variety of cancer types. Namely, Natural Killer (NK), Lymphokine-activated Killer (LAK) cells and Cytokine-induced killer (CIK) cells are the most commonly used cell types in antigen-independent adoptive immunotherapy of cancer. They all originate from peripheral blood mononuclear cells and share several common features in their killing mechanisms. However, despite broad application in clinical settings, the boundaries between these cell types are not very clearly defined. The current study aims to review different aspects of these cell populations in terms of phenotypical characteristic and preparation media, to clarify how the boundaries are set.