Effective activity of cytokine-induced killer cells against autologous metastatic melanoma including cells with stemness features

CSPG4 CAR-redirected Cytokine Induced Killer lymphocytes (CIK) as effective cellular immunotherapy for HLA class I defective melanoma

BACKGROUND

Even acknowledging the game-changing results achieved in the treatment of metastatic melanoma with the use of immune checkpoint inhibitors (ICI), a large proportion of patients (40-60%) still fail to respond or relapse due to the development of resistance. Alterations in the expression of Human Leukocyte Antigen class I (HLA-I) molecules are considered to play a major role in clinical resistance to ICI. Cellular immunotherapy with HLA-independent CAR-redirected lymphocytes is a promising alternative in this challenging setting and dedicated translational models are needed.

METHODS

In this study, we propose an HLA-independent therapeutic strategy with Cytokine Induced Killer lymphocytes (CIK) genetically engineered with a Chimeric Antigen Receptor (CAR) targeting the tumor antigen CSPG4 as effector mechanism. We investigated the preclinical antitumor activity of CSPG4-CAR.CIK in vitro and in a xenograft murine model focusing on patient-derived melanoma cell lines (Mel) with defective expression of HLA-I molecules.

RESULTS

We successfully generated CSPG4-CAR.CIK from patients with metastatic melanoma and reported their intense activity in vitro against a panel of CSPG4-expressing patient-derived Mel. The melanoma killing activity was intense, even at very low effector to target ratios, and not influenced by the expression level (high, low, defective) of HLA-I molecules on target cells. Furthermore, CAR.CIK conditioned medium was capable of upregulating the expression of HLA-I molecules on melanoma cells. A comparable immunomodulatory effect was replicated by treatment of Mel cells with exogenous IFN-γ and IFN-α. The antimelanoma activity of CSPG4-CAR.CIK was successfully confirmed in vivo, obtaining a significant tumor growth inhibition of an HLA-defective Mel xenograft in immunodeficient mice.

CONCLUSIONS

In this study we reported the intense preclinical activity of CSPG4-CAR.CIK against melanoma, including those with low or defective HLA-I expression. Our findings support CSPG4 as a valuable CAR target in melanoma and provide translational rationale for clinical studies exploring CAR-CIK cellular immunotherapies within the challenging setting of patients not responsive or relapsing to immune checkpoint inhibitors.

Murine models to study human NK cells in human solid tumors

Since the first studies, the mouse models have provided crucial support for the most important discoveries on NK cells, on their development, function, and circulation within normal and tumor tissues. Murine tumor models were initially set to study murine NK cells, then, ever more sophisticated human-in-mice models have been developed to investigate the behavior of human NK cells and minimize the interferences from the murine environment. This review presents an overview of the models that have been used along time to study NK cells, focusing on the most popular NOG and NSG models, which work as recipients for the preparation of human-in-mice tumor models, the study of transferred human NK cells, and the evaluation of various enhancers of human NK cell function, including cytokines and chimeric molecules. Finally, an overview of the next generation humanized mice is also provided along with a discussion on how traditional and innovative in-vivo and in-vitro approaches could be integrated to optimize effective pre-clinical studies.

Adjuvant cytokine-induced killer cell immunotherapy improves long-term survival in patients with stage I-II non-small cell lung cancer after curative surgery

BACKGROUND AIMS

Non-small cell lung cancer (NSCLC) remains the most common cancer worldwide, with an annual incidence of around 1.3 million. Surgery represents the standard treatment in early-stage NSCLC when feasible. However, because of cancer recurrence, only approximately 53% of patients with stage I and II NSCLC survive 5 years after radical surgery. The authors performed a retrospective study to investigate the impact of cytokine-induced killer (CIK) cell immunotherapy on the long-term survival of patients with stage I-II NSCLC after curative resection.

METHODS

Fifty-seven patients with NSCLC were included in the study, with 41 and 16 in the control and CIK groups, respectively. Clinical characteristics were compared using a t-test and χ² test. Survival analysis of patients with NSCLC was performed using the Kaplan-Meier method. The phenotypes and anti-tumor functions of CIK cells were evaluated by flow cytometry.

RESULTS

Patients in the CIK group exhibited significantly longer overall survival (OS) and better disease-free survival (DFS) than those in the control group. Subgroup analysis indicated that patients with a higher risk of recurrence benefited more from CIK treatment and attained longer OS and DFS compared with those in the control group. No severe adverse events related to CIK treatment occurred. CIK cells contained a higher proportion of CD3⁺CD56⁺ natural killer (NK) T cells and CD3⁺ and CD8⁺ T cells and a lower proportion of CD3^-CD56⁺ NK cells compared with peripheral blood mononuclear cells. CIK cells exhibited potent tumor-killing ability, with longer contact times with tumor cells and a greater number of cells exposed to tumor cells.

CONCLUSIONS

The authors' data suggest that adjuvant CIK cell therapy is a safe and effective therapeutic strategy for improving OS and DFS in patients with stage I-II NSCLC after curative resection.

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.

Fibroblasts Impair Migration and Antitumor Activity of NK-92 Lymphocytes in a Melanoma-on-Chip Model

Adoptive cell therapy in solid tumors, such as melanoma, is impaired, but little is known about the role that the fibroblasts present in the tumor microenvironment could exert. However, the mechanism at play is not well understood, partly due to the lack of relevant pre-clinical models. Three-dimensional culture and microfluidic chips are used to recapitulate the dynamic interactions among different types of cells in the tumor microenvironment in controlled and physiological settings. In this brief report, we propose a reductionist melanoma-on-a-chip model for evaluating the essential role of fibroblasts in the antitumor activity of lymphocytes. To this end, 3D melanoma spheroids were monocultured and co-cultured with human dermal fibroblasts and the NK-92 cell migration towards the tumor compartment was tested in a commercially available microfluidic device. Utilizing confocal microscopy, we observed the different recruitment of NK-92 cells in the presence and absence of fibroblasts. Our results show that fibroblasts' presence inhibits immune effector recruiting by exploiting a 3D pre-clinical tumor model.

Sintilimab maintenance therapy post first-line cytokine-induced killer cells plus chemotherapy for extensive-stage small cell lung cancer

Despite recent progress in treating advanced non-small cell lung cancer, clinical intervention in extensive-stage small-cell lung cancer (ES-SCLC) remains stagnant. The purpose of this study was to evaluate the clinical efficacy of cytokine-induced killer (CIK) cells combined with cytotoxic chemotherapy, followed by anti-programmed death 1 antibody (sintilimab) maintenance, in ES-SCLC patients. To explore a new method for safe treatment of ES-SCLC patients, thirteen ES-SCLC patients were enrolled between June 2019 and December 2021. All patients received first-line chemotherapy (etoposide plus platinum) combined with CIK cell therapy. Patients who reached a stable disease state or responded well to treatment received sintilimab maintenance treatment. The primary objective of this study was to determine the median overall survival (OS); the secondary objective was to assess the objective response rate (ORR), progression-free survival 1 and 2 (PFS1 was defined as the duration from the signing of informed consent to the date of tumor progression, or death, or the last follow-up. PFS2 was defined as the duration from the first day of sintilimab treatment to the date of tumor progression, death, or the last follow-up.), and adverse reactions. At a 24.1-month follow-up, the median OS was 11.8 (95% confidence interval [CI]: 10.6–13.0) months, median PFS1 was 5.5 (95% CI: 5.0–6.0) months, and the median PFS2 was 2.3 (95% CI: 0.5–4.1) months. The ORR was 76.9% (10/13), the disease control rate was 100% (13/13), and the 20-month survival rate was 41.7%. Eight participants exhibited grade 3 or 4 adverse events after combination therapy. During maintenance treatment with sintilimab, level 3 adverse events occurred in 1 patient (1/9). In conclusion, adding CIK cells to standard chemotherapy regimens, followed by maintenance therapy with sintilimab, may represent a new safe and effective treatment strategy.

Origin and Therapies of Osteosarcoma

Simple Summary

Osteosarcoma is the most common malignant bone tumor in children, with a 5-year survival rate ranging from 70% to 20% depending on the aggressiveness of the disease. The current treatments have not evolved over the past four decades due in part to the genetic complexity of the disease and its heterogeneity. This review will summarize the current knowledge of OS origin, diagnosis and therapies.

Abstract

Osteosarcoma (OS) is the most frequent primary bone tumor, mainly affecting children and young adults. Despite therapeutic advances, the 5-year survival rate is 70% but drastically decreases to 20–30% for poor responders to therapies or for patients with metastasis. No real evolution of the survival rates has been observed for four decades, explained by poor knowledge of the origin, difficulties related to diagnosis and the lack of targeted therapies for this pediatric tumor. This review will describe a non-exhaustive overview of osteosarcoma disease from a clinical and biological point of view, describing the origin, diagnosis and therapies.

The Characteristics of Tumor Microenvironment in Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a special subtype of breast cancer, accounting for 10-20% of breast cancers with high intrinsic heterogeneity. Its unique immune microenvironment, including high expression of vascular endothelial growth factors, tumor infiltrating lymphocytes (TILs), tumor-associated macrophages (TAMs), and other molecules that promote the growth and migration of tumor cells, has been shown to play a dual role in the occurrence, growth, and metastasis of TNBC. Understanding the TNBC microenvironment is of great significance for the prognosis and treatment of TNBC. In this article, we describe the composition and function of immune cells in the TNBC microenvironment and summarize the major cytokine growth factors and chemokines in the TNBC microenvironment. Finally, we discuss the progress of TNBC, cytokine-induced killer cell therapy, and immune checkpoint therapy.

Reporter gene systems for the identification and characterization of cancer stem cells

Cancer stem cells (CSCs) are tumor cells that share functional characteristics with normal and embryonic stem cells. CSCs have increased tumor-initiating capacity and metastatic potential and lower sensitivity to chemo- and radiotherapy, with important roles in tumor progression and the response to therapy. Thus, a current goal of cancer research is to eliminate CSCs, necessitating an adequate phenotypic and functional characterization of CSCs. Strategies have been developed to identify, enrich, and track CSCs, many of which distinguish CSCs by evaluating the expression of surface markers, the initiation of specific signaling pathways, and the activation of master transcription factors that control stemness in normal cells. We review and discuss the use of reporter gene systems for identifying CSCs. Reporters that are under the control of aldehyde dehydrogenase 1A1, CD133, Notch, Nanog homeobox, Sex-determining region Y-box 2, and POU class 5 homeobox can be used to identify CSCs in many tumor types, track cells in real time, and screen for drugs. Thus, reporter gene systems, in combination with in vitro and in vivo functional assays, can assess changes in the CSCs pool. We present relevant examples of these systems in the evaluation of experimental CSCs-targeting therapeutics, demonstrating their value in CSCs research.

Recruitment, Infiltration, and Cytotoxicity of HLA-Independent Killer Lymphocytes in Three-Dimensional Melanoma Models

Simple Summary

Limited therapeutic results of immune checkpoint inhibitors in definite tumor settings, such as melanoma, call for alternative or complementary approaches. Among these, adoptive cell therapy (ACT) by means of HLA-independent tumor killer lymphocytes is a promising approach. We aimed at developing a pre-clinical 3D model to investigate and visualize the interaction between tumor and immune effectors in melanoma. To this aim, we employed Cytokine-Induced Killer cells (CIK) and NK-92 on patient-derived melanoma samples. By means of imaging-based methods, we measured the effector recruitment on the 3D targets, their infiltration, and cytotoxic activity. Our results and methodologies can be easily generalized to other effectors and other classes of tumors and help elucidate fundamental questions on the basic biology and kinetics of immune effector recruitment in a realistic 3D setting mimicking a solid tumor.

Abstract

Cancer adoptive cell therapy (ACT) with HLA-independent tumor killer lymphocytes is a promising approach, with intrinsic features potentially addressing crucial tumor-escape mechanisms of checkpoint inhibitors. Cytokine-induced Killer (CIK) and Natural Killer (NK) lymphocytes share similar tumor-killing mechanisms, with preclinical evidence of intense activity against multiple solid tumors and currently testing in clinical studies. To improve the effective clinical translation of such ACT approaches, several fundamental questions still need to be addressed within appropriate preclinical contexts, capable of overcoming limitations imposed by most traditional two-dimensional assays. Here, we developed a novel experimental approach to explore, dissect, and visualize the interactions of CIK and NK lymphocytes with melanoma tumors in vitro in 3D. Primary melanoma cells were assembled into small tumors that were dispersed in a 3D matrix and challenged with patient-derived CIK or the NK-92 cell line. By means of imaging-based methods, we reported, visualized, and quantitatively measured the recruitment of CIK and NK on the 3D targets, their infiltration, and cytotoxic activity. Our results support the effective tumor recruitment and tumor infiltration by CIK and NK. Such features appeared dependent on the specific geometric aspects of the environment but can be explained in terms of directional migration toward the tumor, without invoking major feedback components. Overall, our 3D platform allows us to monitor the processes of tumor recruitment, infiltration, and killing by means of live measurements, revealing important kinetic aspects of ACT with CIK and NK against melanoma.

Immunotherapy: A Potential Approach to Targeting Cancer Stem Cells

Tumor recurrence and drug resistance are two of the key factors affecting the prognosis of cancer patients. Cancer stem cells (CSCs) are a group of cells with infinite proliferation potential which are not sensitive to traditional therapies, including radio- and chemotherapy. These CSCs are considered to be central to tumor recurrence and the development of drug resistance. In addition, CSCs are important targets in cancer immunotherapy because of their expression of novel tumorassociated antigens, which result from mutations in cancer cells over the course of treatment. Emerging immunotherapies, including cancer vaccines, checkpoint blockade therapies, and transferred immune cell therapies, have all been shown to be more effective when they selectively target CSCs. Such therapies may also provide novel additions to the current therapeutic milieu and may offer new therapeutic combinations for treatment. This review summarizes the relationships between various immunotherapies and CSCs and provides novel insights into potential therapeutic applications for these approaches in the future.

Immune evasion by cancer stem cells

Tumor immunity represents a new avenue for cancer therapy. Immune checkpoint inhibitors have successfully improved outcomes in several tumor types. In addition, currently, immune cell-based therapy is also attracting significant attention. However, the clinical efficacy of these treatments requires further improvement. The mechanisms through which cancer cells escape the immune response must be identified and clarified. Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors. CSCs can initiate tumors in partially immunocompromised mice, whereas non-CSCs fail to form tumors, suggesting that tumor initiation is a definitive function of CSCs. However, the fact that non-CSCs also initiate tumors in more highly immunocompromised mice suggests that the immune evasion property may be a more fundamental feature of CSCs rather than a tumor-initiating property. In this review, we summarize studies that have elucidated how CSCs evade tumor immunity and create an immunosuppressive milieu with a focus on CSC-specific characteristics and functions. These profound mechanisms provide important clues for the development of novel tumor immunotherapies.

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Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors.

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Immune evasion is a fundamental feature of CSCs.

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Immune evasion mechanisms must be precisely clarified to improve tumor immunotherapy.

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CSCs are promising targets for tumor immunotherapy.

Cellular Immunotherapy Targeting Cancer Stem Cells: Preclinical Evidence and Clinical Perspective

The term “cancer stem cells” (CSCs) commonly refers to a subset of tumor cells endowed with stemness features, potentially involved in chemo-resistance and disease relapses. CSCs may present peculiar immunogenic features influencing their homeostasis within the tumor microenvironment. The susceptibility of CSCs to recognition and targeting by the immune system is a relevant issue and matter of investigation, especially considering the multiple emerging immunotherapy strategies. Adoptive cellular immunotherapies, especially those strategies encompassing the genetic redirection with chimeric antigen receptors (CAR), hold relevant promise in several tumor settings and might in theory provide opportunities for selective elimination of CSC subsets. Initial dedicated preclinical studies are supporting the potential targeting of CSCs by cellular immunotherapies, indirect evidence from clinical studies may be derived and new studies are ongoing. Here we review the main issues related to the putative immunogenicity of CSCs, focusing on and highlighting the existing evidence and opportunities for cellular immunotherapy approaches with T and non-T antitumor lymphocytes.

Multidirectional Strategies for Targeted Delivery of Oncolytic Viruses by Tumor Infiltrating Immune Cells

Oncolytic virus (OV) immunotherapy has demonstrated to be a promising approach in cancer treatment due to tumor-specific oncolysis. However, their clinical use so far has been largely limited due to the lack of suitable delivery strategies with high efficacy. Direct 'intratumoral' injection is the way to cross the hurdles of systemic toxicity, while providing local effects. Progress in this field has enabled the development of alternative way using 'systemic' oncolytic virotherapy for producing better results. One major potential roadblock to systemic OV delivery is the low virus persistence in the face of hostile immune system. The delivery challenge is even greater when attempting to target the oncolytic viruses into the entire tumor mass, where not all tumor cells are equally exposed to exactly the same microenvironment. The microenvironment of many tumors is known to be massively infiltrated with various types of leucocytes in both primary and metastatic sites. Interestingly, this intratumoral immune cell heterogeneity exhibits a degree of organized distribution inside the tumor bed as evidenced, for example, by the hypoxic tumor microenviroment where predominantly recruits tumor-associated macrophages. Although in vivo OV delivery seems complicated and challenging, recent results are encouraging for decreasing the limitations of systemically administered oncolytic viruses and an improved efficiency of oncolytic viral therapy in targeting cancerous tissues in vitro. Here, we review the latest developments of carrier cell-based oncolytic virus delivery using tumor-infiltrating immune cells with a focus on the main features of each cellular vehicle.

Preclinical immunotherapy with Cytokine-Induced Killer lymphocytes against epithelial ovarian cancer

Despite improvements in surgery and medical treatments, epithelial ovarian cancer (EOC) remains the most lethal gynaecological malignancy. Aim of this study is to investigate the preclinical immunotherapy activity of cytokine-induced killer lymphocytes (CIK) against epithelial ovarian cancers, focusing on platinum-resistant settings. We generated CIK ex vivo starting from human peripheral blood samples (PBMCs) collected from EOC patients. Their antitumor activity was tested in vitro and in vivo against platinum-resistant patient-derived ovarian cancer cells (pdOVCs) and a Patient Derived Xenograft (PDX), respectively. CIK were efficiently generated (48 fold median ex vivo expansion) from EOC patients; pdOVCs lines (n = 9) were successfully generated from metastatic ascites; the expression of CIK target molecules by pdOVC confirmed pre and post treatment in vitro with carboplatin. The results indicate that patient-derived CIK effectively killed autologous pdOVCs in vitro. Such intense activity was maintained against a subset of pdOVC that survived in vitro treatment with carboplatin. Moreover, CIK antitumor activity and tumor homing was confirmed in vivo within an EOC PDX model. Our preliminary data suggest that CIK are active in platinum resistant ovarian cancer models and should be therefore further investigated as a new therapeutic option in this extremely challenging setting.

Efficacy of cascade-primed cell infusion as an adjuvant immunotherapy with concurrent chemotherapy for patients with non-small-cell lung cancer: A retrospective observational study with a 5-year follow-up

BACKGROUND

Clinical studies have shown the efficacy of combination therapy for various malignancies. In this study, the characteristics, safety and feasibility of use of cascade-primed (CAPRI) cells for the combination treatment of non-small-cell lung cancer (NSCLC) were evaluated both in vitro and in vivo.

METHODS

Sixty-five patients with stage II-IV NSCLC were recruited. Of these patients, 31 patients received CAPRI cell therapy combined with chemotherapy (CAPRI group), and the other 34 patients constituted the control group and received chemotherapy alone. This study primarily aimed to evaluate the overall survival (OS), progression-free survival (PFS), short-term responses and treatment efficacy.

RESULTS

CD83, CD1a, CD80 and CD86 marker levels were significantly upregulated in CAPRI cells. Interferon-γ expression levels were highest in CD3⁺CD8⁺ cells (33.77% ± 4.40%). Furthermore, interleukin-2 levels were highest in CD3⁺CD56⁺ cells (26.73% ± 6.63%), whereas perforin expression levels were similar in CD3⁺CD8⁺ and CD3⁺CD56⁺ cells. Furthermore, CAPRI cells had a better anti-tumor potential in CD3⁺CD56⁺ cells and displayed the highest expression levels of CD107a to H460 and A549 cell lines. The 5-year OS was significantly greater in the CAPRI group than in the control group (P = 0.008), and the PFS of two groups exhibited a significant difference (P = 0.007). Median OS (48 versus 31.6 months; P = 0.004) and PFS (48 versus 36.4 months; P = 0.016) differed between these two groups. Moreover, treatment-associated toxicities were mild and well-tolerated by patients with NSCLC.

CONCLUSION

CAPRI cell therapy potentially prolongs the survival of patients with NSCLC when combined with chemotherapy.

Aldehyde dehydrogenase-positive melanoma stem cells in tumorigenesis, drug resistance and anti-neoplastic immunotherapy

Cancer stem cells (CSCs), a rare subset of cancer cells, are well known for their self-renewing capacity. CSCs play a critical role in therapeutic failure and are responsible for poor prognosis in leukemia and various solid tumors. However, it is still unclear how CSCs initiate carcinogenesis and evade the immune response. In humans, the melanoma initiating cells (MICs) are recognized as the CSCs in melanomas, and were verified to possess CSC potentials. The enzymatic system, aldehyde dehydrogenase (ALDH) is considered to be a specific marker for CSCs in several tumors. The expression of ALDH in MICs may be closely correlated with phenotypic heterogeneity, melanoma-genesis, metastasis, and drug resistance. The ALDH⁺ CSCs/MICs not only serve as an indicator for therapeutic efficacy, but have also become a target for the treat of melanoma. In this review, we initially introduce the multiple capacities of MICs in melanoma. Then, we summarize in vivo and in vitro studies that illustrate the relationship between ALDH and MICs. Furthermore, understanding of chemotherapy resistance in melanoma relies on ALDH⁺ MICs. Finally, we review studies that focus on melanoma immunotherapies, rendering ALDH a potential marker to evaluate the efficacy of anti-neoplastic therapies or an adjuvant anti-melanoma target.

CAR-Based Strategies beyond T Lymphocytes: Integrative Opportunities for Cancer Adoptive Immunotherapy

Chimeric antigen receptor (CAR)-engineered T lymphocytes (CAR Ts) produced impressive clinical results against selected hematological malignancies, but the extension of CAR T cell therapy to the challenging field of solid tumors has not, so far, replicated similar clinical outcomes. Many efforts are currently dedicated to improve the efficacy and safety of CAR-based adoptive immunotherapies, including application against solid tumors. A promising approach is CAR engineering of immune effectors different from αβT lymphocytes. Herein we reviewed biological features, therapeutic potential, and safety of alternative effectors to conventional CAR T cells: γδT, natural killer (NK), NKT, or cytokine-induced killer (CIK) cells. The intrinsic CAR-independent antitumor activities, safety profile, and ex vivo expansibility of these alternative immune effectors may favorably contribute to the clinical development of CAR strategies. The proper biological features of innate immune response effectors may represent an added value in tumor settings with heterogeneous CAR target expression, limiting the risk of tumor clonal escape. All these properties bring out CAR engineering of alternative immune effectors as a promising integrative option to be explored in future clinical studies.

Cancer stem cell immunology and immunotherapy: Harnessing the immune system against cancer's source

Despite recent advances in diagnosis and therapy having improved cancer outcome, many patients still do not respond to treatments, resulting in the progression or relapse of the disease, eventually impairing survival expectations. The limited efficacy of therapy is often attributable to its inability to affect cancer stem cells (CSCs), a small population of cells resistant to current radio- and chemo-therapies. CSCs are characterized by self-renewal and tumor-initiating capabilities, and function as a reservoir for the local and distant recurrence of the disease. Therefore, new therapeutic approaches able to effectively target and deplete CSCs are urgently needed. Immunotherapy is facing a renewed interest for its potential in cancer treatment, and the possibility of harnessing the immune system to target CSCs is being addressed by a new exciting research field. In this chapter, we discuss the cancer stem cell model and illustrate CSC biological and molecular properties, critically addressing theoretical and practical issues linked with their definition and study. We then review the existing literature regarding the immunological properties of CSCs and the complex interplay occurring between CSCs and immune cells. Finally, we present up-to-date studies on CSC immunotargeting and its potential future perspective. In conclusion, understanding the interplay between CSC biology and tumor immunology will provide a deeper understanding of the mechanisms that regulate CSC immunological properties. This will contribute to the design of new CSC-directed immunotherapeutic strategies with the potential of strongly improving cancer outcomes.

Adjuvant treatment for triple-negative breast cancer: a retrospective study of immunotherapy with autologous cytokine-induced killer cells in 294 patients

Objective

To examine the efficacy and safety of a sequential combination of chemotherapy and autologous cytokine-induced killer (CIK) cell treatment in triple-negative breast cancer (TNBC) patients.

Methods

A total of 294 post-surgery TNBC patients participated in the research from January 1, 2009 to January 1, 2015. After adjuvant chemotherapy, autologous CIK cells were introduced in 147 cases (CIK group), while adjuvant chemotherapy alone was used to treat the remaining 147 cases (control group). The major endpoints of the investigation were the disease-free survival (DFS) and overall survival (OS). Additionally, the side effects of the treatment were evaluated.

Results

In the CIK group, the DFS and OS intervals of the patients were significantly longer than those of the control group (DFS: P = 0.047; OS: P = 0.007). The multivariate analysis demonstrated that the TNM (tumor-node-metastasis) stage and adjuvant CIK treatment were independent prognostic factors for both DFS [hazard ratio (HR) = 0.520, 95% confidence interval (CI):0.271-0.998, P = 0.049; HR = 1.449, 95% CI:1.118-1.877, P = 0.005, respectively] and OS (HR=0.414, 95% CI:0.190-0.903, P = 0.027; HR = 1.581, 95% CI:1.204-2.077, P = 0.001, respectively) in patients with TNBC. Additionally, longer DFS and OS intervals were associated with increased number of CIK treatment cycles (DFS: P = 0.020; OS: P = 0.040). The majority of the patients who benefitted from CIK cell therapy were relatively early-stage TNBC patients.

Conclusion

Chemotherapy in combination with adjuvant CIK could be used to lower the relapse and metastasis rate, thus effectively extending the survival time of TNBC patients, especially those at early stages.

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.

Clinical Effect of Adjuvant Cytokine-Induced Killer Cells Immunotherapy in Patients with Stage II-IVB Nasopharyngeal Carcinoma after Chemoradiotherapy: A propensity score analysis

As an adjuvant immunotherapy, cytokine-induced killer cells (CIKs) infusion has been demonstrated to exert potent effectiveness in several types of cancer patients who received curative treatment. However, controversy exists regarding whether nasopharyngeal carcinoma (NPC) patients can benefit from additional treatment after radical radiotherapy or chemoradiotherapy to improve their distant control and survival. In this retrospective study, we aimed to evaluate the efficacy of adjuvant CIK cells therapy in NPC patients with stage II-IVB after curative treatment. From January 1, 2005 to December 31, 2012, 85 pairs of NPC patients matching by propensity score matching (PSM) method to balance prognostic factors were included in this study: 85 cases underwent radical treatment, 85 cases received radical treatment and sequential CIKs infusion. We found that disease-free survival (DFS) and overall survival (OS) were significantly better in the CIK group than that in the control group (P = 0.009, P < 0.001, respectively). Adjuvant CIK cells immunotherapy was showed to be an independent prognostic factor for survival of the patients in further multivariate analysis. In subgroup analyses, the DFS and OS of patients with T3/4, III and IV A-B TNM (tumor-node-metastasis) stages were significantly enhanced in CIK group compared to control group. Nevertheless, both NPC patients with high and low EBV DNA benefited from adjuvant CIK cells immunotherapy. In conclusion, CIKs infusion is an effective adjuvant immunotherapy for enhancing the prognosis of NPC patients who have received the standard treatment, particularly for those with more aggressive tumor (T3/4) or advanced TNM stage.

Cytokine Induced Killer cells are effective against sarcoma cancer stem cells spared by chemotherapy and target therapy

Metastatic bone and soft tissue sarcomas often relapse after chemotherapy (CHT) and molecular targeted therapy (mTT), maintaining a severe prognosis. A subset of sarcoma cancer stem cells (sCSC) is hypothesized to resist conventional drugs and sustain disease relapses. We investigated the immunotherapy activity of cytokine induced killer cells (CIK) against autologous sCSC that survived CHT and mTT. The experimental platform included two aggressive bone and soft tissue sarcoma models: osteosarcoma (OS) and undifferentiated-pleomorphic sarcoma (UPS).

To visualize putative sCSC we engineered patient-derived sarcoma cultures (2 OS and 3 UPS) with a lentiviral sCSC-detector wherein the promoter of stem-gene Oct4 controls the expression of eGFP.

We visualized a fraction of sCSC (mean 24.2 ± 5.2%) and confirmed their tumorigenicity in vivo. sCSC resulted relatively resistant to both CHT and mTT in vitro. Therapeutic doses of doxorubicin significantly enriched viable eGFP⁺sCSC in both OS (2.6 fold, n = 16) and UPS (2.3 fold, n = 29) compared to untreated controls. Treatment with sorafenib (for OS) and pazopanib (for UPS) also determined enrichment (1.3 fold) of viable eGFP⁺sCSC, even if less intense than what observed after CHT.

Sarcoma cells surviving CHT and mTT were efficiently killed in vitro by autologous CIK even at minimal effector/target ratios (40:1 = 82%, 1:4 = 29%, n = 13). CIK immunotherapy did not spare sCSC that were killed as efficiently as whole sarcoma cell population. The relative chemo-resistance of sCSC and sensitivity to CIK immunotherapy was confirmed in vivo. Our findings support CIK as an innovative, clinically explorable, approach to eradicate chemo-resistant sCSC implicated in tumor relapse.

Combination therapy improves immune response and prognosis in patients with advanced oral mucosal melanoma: A clinical treatment success

OBJECTIVE

This study was undertaken to analyze disease response and immune response to assess treatment effectiveness and success in patients with advanced oral mucosal melanoma treated with cytokines injection, cryosurgery, and adoptive cell transfer therapy.

STUDY DESIGN

Ten patients were enrolled in the study, and the relevant characteristics and immunologic differences were evaluated.

RESULTS

All patients achieved an objective clinical response according to the Response Evaluation Criteria in Solid Tumors, including 7 cases of continuing complete remission (55, 27, 87 + , 58⁺, 58 + , 45 + , and 37 + months) and 3 cases of partial remission (30, 12, and 9 months). Five responders are currently alive. After combination therapy, we observed that the proportion of CD3+ lymphocytes and the secretion of interferon-γ increased, whereas interleukin-10 decreased. In the assay of improved cytokine-induced killer cells, CD4+CD25+ regulatory T cells declined, and natural killer cells upregulated. Meanwhile, the proliferation rate of in vitro cultured improved cytokine-induced killer cells improved after courses of therapy.

CONCLUSIONS

Combination therapy of cytokine injection, cryosurgery, and transfer of improved cytokine-induced killer cells may be a promising approach for patients with oral mucosal melanoma.

Efficiency of Cytokine-Induced Killer Cells in Combination with Chemotherapy for Triple-Negative Breast Cancer

Purpose

The treatment of triple-negative breast cancer (TNBC) remains challenging, due to the absence of estrogen, progesterone, and human epidermal growth factor receptors. This study was designed to evaluate the efficiency and safety of cytokine-induced killer (CIK) cell immunotherapy, following regular chemotherapy, for patients with TNBC.

Methods

A total of 340 patients with postmastectomy TNBC, from January 1, 2010 to June 30, 2014, were included in this retrospective study. Seventy-seven patients received CIK cell immunotherapy, following regular chemotherapy (arm 1), and 263 patients received regular chemotherapy alone (arm 2). The primary aim was overall survival (OS) and disease-free survival (DFS), and the treatment responses and adverse events were also evaluated.

Results

The 5-year DFS and OS rates in arm 1 were 77.9% and 94.3%, compared with 69.8% and 85.6% in arm 2, respectively (p=0.159 and p=0.035, respectively). This clearly shows that there was no statistical difference in the 5-year DFS between the two groups. Multivariate analyses of arm 1 indicated that a Karnofsky performance score (KPS) ≥90 and stage I/IIA disease were significantly associated with a prolonged DFS period (hazard ratio [HR], 0.25; 95% confidence interval [CI], 0.09–0.74; p=0.012; and HR 0.21; 95% CI, 0.06–0.82; p=0.024, respectively), but a KPS ≥90 and stage I/IIA disease were not independent prognostic factors for OS. Toxicity was mild in patients who received the CIK therapy.

Conclusion

The data suggested that CIK cell immunotherapy improved the efficiency of regular chemotherapy in patients with TNBC, and the side effects of CIK cell immunotherapy were mild.

Cytokine-Induced Killer Cells Express CD39, CD38, CD203a, CD73 Ectoenzymes and P1 Adenosinergic Receptors

Cytokine-induced killer (CIK) cells, a heterogeneous T cell population obtained by in vitro differentiation of peripheral blood mononuclear cells (PBMC), represent a promising immunological approach in cancer. Numerous studies have explored the role of CD38, CD39, CD203a/PC-1, and CD73 in generating extracellular adenosine (ADO) and thus in shaping the tumor niche in favor of proliferation. The findings shown here reveal that CIK cells are able to produce extracellular ADO via traditional (CD39/CD73) and/or alternative (CD38/CD203a/CD73 or CD203a/CD73) pathways. Transcriptome analysis showed the mRNA expression of these molecules and their modulation during PBMC to CIK differentiation. When PBMC from normal subjects or cancer bearing patients were differentiated into CIK cells under normoxic conditions, CD38 and CD39 were greatly up-regulated while the number of CD203a, and CD73 positive cells underwent minor changes. Since hypoxic conditions are often found in tumors, we asked whether CD39, CD38, CD203a, and CD73 expressed by CIK cells were modulated by hypoxia. PBMC isolated from cancer patients and differentiated into CIK cells in hypoxic conditions did not show relevant changes in CD38, CD39, CD73, CD203a, and CD26. CIK cells also expressed A₁, A_2A, and A_2B ADO receptors and they only underwent minor changes as a consequence of hypoxia. The present study sheds light on a previously unknown functional aspect of CIK cells, opening the possibility of pharmacologically modulated ADO-generating ectoezymes to improve CIK cells performance.

BRAF and MEK Inhibitors Increase PD-1-Positive Melanoma Cells Leading to a Potential Lymphocyte-Independent Synergism with Anti-PD-1 Antibody

Purpose: BRAF and MEK inhibitors (BRAF/MEKi) favor melanoma-infiltrating lymphocytes, providing the rationale for current combinatorial trials with anti-PD-1 antibody. A portion of melanoma cells may express PD-1, and anti-PD-1 antibody could have a direct antitumor effect. Here, we explore whether BRAF/MEKi modulate rates of PD-1⁺ melanoma cells, supporting an additional-lymphocyte-independent-basis for their therapeutic combination with anti-PD-1 antibody.Experimental Design: With data mining and flow cytometry, we assessed PD-1, PD-L1/2 expression on melanoma cell lines (CCLE, N = 61; validation cell lines, N = 7) and melanoma tumors (TCGA, N = 214). We explored in vitro how BRAF/MEKi affect rates of PD-1⁺, PD-L1/2⁺ melanoma cells, and characterized the proliferative and putative stemness features of PD-1⁺ melanoma cells. We tested the functional lymphocyte-independent effect of anti-PD-1 antibody alone and in combination with BRAF/MEKi in vitro and in an in vivo immunodeficient murine model.Results: PD-1 is consistently expressed on a small subset of melanoma cells, but PD-1⁺ cells increase to relevant rates during BRAF/MEKi treatment [7.3% (5.6-14.2) vs. 1.5% (0.7-3.2), P = 0.0156; N = 7], together with PD-L2⁺ melanoma cells [8.5% (0.0-63.0) vs. 1.5% (0.2-43.3), P = 0.0312; N = 7]. PD-1⁺ cells proliferate less than PD-1^- cells (avg. 65% less; t = 7 days) and are preferentially endowed with stemness features. In vivo, the direct anti-melanoma activity of PD-1 blockage as monotherapy was negligible, but its association with BRAF/MEKi significantly delayed the development of drug resistance and tumor relapse.Conclusions: BRAF/MEKi increase the rates of PD-1⁺ melanoma cells that may sustain tumor relapse, providing a lymphocyte-independent rationale to explore combinatory strategies with anti-PD-1 antibody. Clin Cancer Res; 24(14); 3377-85. ©2018 AACR.

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.

PLAC1-specific TCR-engineered T cells mediate antigen-specific antitumor effects in breast cancer

Placenta-specific 1 (PLAC1), a novel cancer-testis antigen (CTA), is expressed in a number of different human malignancies. It is frequently produced in breast cancer, serving a function in tumorigenesis. Adoptive immunotherapy using T cell receptor (TCR)-engineered T cells against CTA mediates objective tumor regression; however, to the best of our knowledge, targeting PLAC1 using engineered T cells has not yet been attempted. In the present study, the cDNAs encoding TCRα- and β-chains specific for human leukocyte antigen (HLA)-A*0201-restricted PLAC1 were cloned from a cytotoxic T-lymphocyte, generated by in vitro by the stimulation of CD8+ T cells using autologous HLA-A2+ dendritic cells loaded with a PLAC1-specific peptide (p28-36, VLCSIDWFM). The TCRα/β-chains were linked by a 2A peptide linker (TCRα-Thosea asigna virus-TCRβ), and the constructs were cloned into the lentiviral vector, followed by transduction into human cytotoxic (CD8+) T cells. The efficiency of transduction was up to 25.16%, as detected by PLAC1 multimers. TCR-transduced CD8+ T cells, co-cultured with human non-metastatic breast cancer MCF-7 cells (PLAC1+, HLA-A2+) and triple-negative breast cancer MDAMB-231 cells (PLAC1+, HLA-A2+), produced interferon γ and tumor necrosis factor α, suggesting TCR activation. Furthermore, the PLAC1 TCR-transduced CD8+ T cells efficiently and specifically identified and annihilated the HLA-A2+/PLAC1+ breast cancer cell lines in a lactate dehydrogenase activity assay. Western blot analysis demonstrated that TCR transduction stimulated the production of mitogen-activated protein kinase signaling molecules, extracellular signal-regulated kinases 1/2 and nuclear factor-κB, through phosphoinositide 3-kinase γ-mediated phosphorylation of protein kinase B in CD8+ T cells. Xenograft mouse assays revealed that PLAC1 TCR-transduced CD8+T cells significantly delayed the tumor progression in mice-bearing breast cancer compared with normal saline or negative control-transduced groups. In conclusion, a novel HLA-A2-restricted and PLAC1-specific TCR was identified. The present study demonstrated PLAC1 to be a potential target for breast cancer treatment; and the usage of PLAC1-specific TCR-engineered T cells may be a novel strategy for PLAC1-positive breast cancer treatment.

CD44v6 as innovative sarcoma target for CAR-redirected CIK cells

Purpose of our study was to explore a new immunotherapy for high grade soft tissue sarcomas (STS) based on cytokine-induced killer cells (CIK) redirected with a chimeric antigen receptor (CAR) against the tumor-promoting antigen CD44v6. We aimed at generating bipotential killers, combining the CAR specificity with the intrinsic tumor-killing ability of CIK cells (CAR⁺.CIK). We set a patient-derived experimental platform. CAR⁺.CIK were generated by transduction of CIK precursors with a lentiviral vector encoding for anti-CD44v6-CAR. CAR⁺.CIK were characterized and assessed in vitro against multiple histotypes of patient-derived STS. The anti-sarcoma activity of CAR⁺.CIK was confirmed in a STS xenograft model. CD44v6 was expressed by 40% (11/27) of patient-derived STS. CAR⁺.CIK were efficiently expanded from patients (n = 12) and killed multiple histotypes of STS (including autologous targets, n = 4). The killing activity was significantly higher compared with unmodified CIK, especially at low effector/target (E/T) ratios: 98% vs 82% (E/T = 10:1) and 68% vs 26% (1:4), (p<0.0001). Specificity of tumor killing was confirmed by blocking with anti-CD44v6 antibody. CAR⁺.CIK produced higher amounts of IL6 and IFN-γ compared to control CIK. CAR⁺.CIK were highly active in mice bearing subcutaneous STS xenografts, with significant delay of tumor growth (p<0.0001) without toxicities.

We report first evidence of CAR⁺.CIK's activity against high grade STS and propose CD44v6 as an innovative target in this setting. CIK are a valuable platform for the translation of CAR-based strategies to challenging field of solid tumors. Our findings support the exploration of CAR⁺.CIK in clinical trials against high grade STS.

Reporter Systems to Study Cancer Stem Cells

Cancer stem cells have been identified in primary tumors, patient derived xenografts, and established cancer cell lines. The development of reporters has enabled investigators to rapidly enrich for these cells and more importantly track these cells in real time. Here we describe the current state of the reporter field and their use and limitations in multiple cancers.

Identification of a protein associated with the activity of cytokine-induced killer cells

Cytokine-induced killer cells (CIKs) adoptive immunotherapy for efficient antitumor ability is used clinically, but details regarding the proteins associated with CIK activity remain unclear. In the current study, the cytotoxicity of CIKs on hepatoma was identified to be significantly downregulated by 1.61-fold following gentamincin treatment. Further research revealed that a differentially expressed protein (P43) was significantly downregulated by 1.22-fold using one-dimensional gel electrophoresis analysis. Of these, the P43 was identified as human haptoglobin using liquid chromatography-mass spectrometry. Western blotting demonstrated that the haptoglobin specifically reacted with rabbit anti-human-haptoglobin. Furthermore, western blotting results verified that the haptoglobin was significantly downregulated by 1.17-fold compared with the control group. In addition, the expression of haptoglobin mRNA was significantly downregulated by 1.73-fold following gentamincin treatment. Taken together, the results of the present study demonstrated that the expression of haptoglobin protein was associated with the activity of CIKs, and the results will be beneficial to the further investigation of CIK activity-enhancement mechanism.

Melanoma: Genetic Abnormalities, Tumor Progression, Clonal Evolution and Tumor Initiating Cells

Melanoma is an aggressive neoplasia issued from the malignant transformation of melanocytes, the pigment-generating cells of the skin. It is responsible for about 75% of deaths due to skin cancers. Melanoma is a phenotypically and molecularly heterogeneous disease: cutaneous, uveal, acral, and mucosal melanomas have different clinical courses, are associated with different mutational profiles, and possess distinct risk factors. The discovery of the molecular abnormalities underlying melanomas has led to the promising improvement of therapy, and further progress is expected in the near future. The study of melanoma precursor lesions has led to the suggestion that the pathway of tumor evolution implies the progression from benign naevi, to dysplastic naevi, to melanoma in situ and then to invasive and metastatic melanoma. The gene alterations characterizing melanomas tend to accumulate in these precursor lesions in a sequential order. Studies carried out in recent years have, in part, elucidated the great tumorigenic potential of melanoma tumor cells. These findings have led to speculation that the cancer stem cell model cannot be applied to melanoma because, in this malignancy, tumor cells possess an intrinsic plasticity, conferring the capacity to initiate and maintain the neoplastic process to phenotypically different tumor cells.

Analytic and Dynamic Secretory Profile of Patient-Derived Cytokine-Induced Killer Cells

Adoptive immunotherapy with Cytokine Induced Killer (CIK) cells has shown antitumor activity against several kinds of cancers in preclinical models and clinical trials. CIK cells are a subset of ex vivo expanded T lymphocytes with T-NK phenotype and MHC-unrestricted antitumor activity. Literature provides scanty information on cytokines, chemokines and growth factors secreted by CIK cells. Therefore, we investigated the secretory profile of CIK cells generated from tumor patients. The secretome analysis was performed at specific time points (day 1, day 14 and day 21) of CIK cells expansion. Mature CIK cells (day 21) produce a great variety of interleukins and secreted proteins that can be divided into 3 groups based on their secretion quantity: high (IL-13, RANTES, MIP-1α and 1β), medium (IL-1Ra, IL-5, IL-8, IL-10, IL-17, IP-10, INF-γ, VEGF and GMCSF) and low (IL-1β, IL-4, IL-6, IL-7, IL-9, IL-12, IL-15, Eotaxin, PDGF-bb, FGF basic, G-CSF and MCP-1) secreted. Moreover, comparing PBMC (day 1) and mature CIK cells (day 14 and 21) secretome, we observed that IL-5, IL-10, IL-13, GM-CSF, VEGF resulted greatly up-regulated, while IL-1β, IL-6, IL-8, IL-15, IL-17, eotaxin, MCP-1, and RANTES were down-regulated. We also performed a gene expression profile analysis of patient-derived CIK cells showing that mRNA for the different cytokines and secreted proteins were modulated during PBMC to CIK differentiation. We highlighted previously unknown secretory properties and provided for the first time a comprehensive molecular characterization of CIK cells. Our findings provide rationale to explore the functional implications and possible therapeutic modulation of CIK secretome.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

5T4-specific chimeric antigen receptor modification promotes the immune efficacy of cytokine-induced killer cells against nasopharyngeal carcinoma stem cell-like cells

Relapse and metastasis of nasopharyngeal carcinoma (NPC) are presumably attributed to cancer stem cells (CSCs). In recent years, chimeric antigen receptor (CAR)-modified immune effector cells have been shown to have impressive antitumour efficacy. In this study, we aimed to identify appropriate tumour-associated antigens predominantly expressed on NPC stem cells (NPCSCs) and determine their suitability for CAR-engineered cytokine-induced killer (CIK) cell therapy against NPC. By investigating the expression patterns of potential target antigens (ROR1, 5T4 and CAIX) in NPC, we found that the oncofetal antigen 5T4 was predominately expressed in NPC cell lines and tissues but absent in non-cancerous nasopharyngeal tissues. Moreover, significantly enhanced expression of 5T4 in NPC spheroids revealed its relationship with putative NPCSCs. Hence, we designed a CAR construct (5T4-28Z) specific for 5T4 and generated CAR-transduced CIK cells. Our results showed that the artificial CAR was efficiently expressed on the surface of CIK cells and that no native phenotypes were altered by the gene transduction. Functional assays revealed that 5T4-28Z-CIK cells possessed both CAR-mediated and CAR-independent anti-NPC activity and were capable of efficiently attacking NPC cells, especially NPCSC-like cells in vitro, suggesting that they might serve as an attractive tool for developing efficient therapies against NPC.

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

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

Selective effect of cytokine-induced killer cells on survival of patients with early-stage melanoma

Adoptive immunotherapy using cytokine-induced killer (CIK) cells has shown potential antitumor ability against several kinds of cancers, including melanoma. However, little is known about the achievable outcome of CIK cells in melanoma patients at different pathological stages. Here we recruited 55 patients treated with conventional therapy plus CIK cells as the CIK group, and 49 patients treated with conventional therapy alone as the control group. The pathological characteristics were comparable between two groups, with a follow-up period up to 40 months. Survival data and immune responses were evaluated after CIK cell treatment. In this study, CIK cells were successfully generated from peripheral blood of melanoma patients after in vitro culture for 14 days. The cultured CIK cells not only produced high levels of pro-inflammatory cytokines upon in vitro stimulation but also efficiently killed human melanoma cell lines. No serious side events were observed in all patients treated with CIK cells. Furthermore, infusions of CIK cells improved the quality of life in some patients, including advanced cases. More importantly, the CIK group exhibited better survival rates compared to the control group among early-stage melanoma patients, in consistent with the increased frequency of peripheral CD4+ T cells. However, the patients with advanced-stage melanoma did not benefit from the CIK cell therapy in terms of survival rate. In conclusion, CIK cells combined with conventional treatments may prolong the survival of early-stage melanoma patients and improve the quality of life for some advanced cases in a safe way.

[Molecular markers of cancer stem cells verified in vivo]

This systematic review aims to analyze molecular markers of cancer stem cells. Only studies that confirmed tumor-initiating capacity of this population by in vivo assay in immunodeficient mice were included. Final sample of papers that fully correspond with initial aim consists of 97 original studies. The results of their analysis reveal that markers commonly used for cancer stem cells deriving were as follows: CD133, СD44, ALDH, CD34, CD24 and EpCAM. The review also contains description of molecular features of some cancer stem cell markers, modern approaches to cancer treatment by targeting this population and brief assessment of cancer stem cell theory development.

Cytokine-Induced Killer Cells Kill Chemo-surviving Melanoma Cancer Stem Cells

Purpose: The MHC-unrestricted activity of cytokine-induced killer (CIK) cells against chemo-surviving melanoma cancer stem cells (mCSC) was explored, as CSCs are considered responsible for chemoresistance and relapses.Experimental Design: Putative mCSCs were visualized by engineering patient-derived melanoma cells (MC) with a lentiviral vector encoding eGFP under expression control by stemness gene promoter oct4 Their stemness potential was confirmed in vivo by limiting dilution assays. We explored the sensitivity of eGFP⁺ mCSCs to chemotherapy (CHT), BRAF inhibitor (BRAFi) or CIK cells, as single agents or in sequence, in vitro First, we treated MCs in vitro with fotemustine or dabrafenib (BRAF-mutated cases); then, surviving MCs, enriched in mCSCs, were challenged with autologous CIK cells. CIK cell activity against chemoresistant mCSCs was confirmed in vivo in two distinct immunodeficient murine models.Results: We visualized eGFP⁺ mCSCs (14% ± 2.1%) in 11 MCs. The tumorigenic precursor rate in vivo was higher within eGFP⁺ MCs (1/42) compared with the eGFP^- counterpart (1/4,870). In vitro mCSCs were relatively resistant to CHT and BRAFi, but killed by CIK cells (n = 11, 8/11 autologous), with specific lysis ranging from 95% [effector:tumor ratio (E:T), 40:1] to 20% (E:T 1:3). In vivo infusion of autologous CIK cells into mice bearing xenografts from three distinct melanomas demonstrated significant tumor responses involving CHT-spared eGFP⁺ mCSCs (P = 0.001). Sequential CHT-immunotherapy treatment retained antitumor activity (n = 12, P = 0.001) reducing mCSC rates (P = 0.01).Conclusions: These findings are the first demonstration that immunotherapy with CIK cells is active against autologous mCSCs surviving CHT or BRAFi. An experimental platform for mCSC study and rationale for CIK cells in melanoma clinical study is provided. Clin Cancer Res; 23(9); 2277-88. ©2016 AACR.

Dendritic cell-activated cytokine-induced killer cell-mediated immunotherapy is safe and effective for cancer patients >65 years old

Individuals >65 years old account for a large proportion of cancer patients, and usually have poor prognoses due to relative weaker physiological function and lower drug tolerance. To characterize the efficacy and safety of dendritic cell (DC)-activated cytokine-induced killer cell (CIK)-mediated treatment, and develop an adoptive immunotherapy for cancer patients >65 years old, a retrospective study was performed in 58 cancer sufferers who received 1-4 cycles of DC-activated CIK (DC-CIK) treatment and evaluated the response (tumor remission rate) and toxicity (side effects to the treatment). The present results showed that DCs and CIKs could be expanded rapidly in vitro, and following co-culture with DCs, the population of cluster of differentiation (CD) 3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺ and CD3⁺CD56⁺ CIKs was significantly increased compared to CIKs without DC activation (P=0.044). In addition, DC-CIK infusion produced marked clinical outcomes, resulting in an objective remission rate, overall clinical benefit rate and Karnofsky performance status of 44.83, 75.86 and 87.28±5.46%, respectively, which was significantly improved compared with prior to treatment (P<0.05). Additionally, subsequent to two cycles of this immunotherapy, several tumor marker expression levels declined, returning to the normal range. The proportion of CD3⁺CD4⁺ (P=0.017) and CD3⁺CD8⁺ (P=0.023) lymphocytes, and the population of CD4/CD8 cells (P=0.024) were also increased. In conclusion, the present study suggests that the immunotherapy mediated by DC-CIK is safe and effective for cancer patients aged >65 years.

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.

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

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

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.

Biological Character of RetroNectin Activated Cytokine-Induced Killer Cells

Adoptive cell therapy (ACT) using autologous cytokine-induced killer (CIK) cells is a promising treatment for metastatic carcinomas. In this study, we investigated the impact of RetroNectin on the proliferation, phenotype alternation, cytokine secretion, and cytotoxic activity of CIK cells from pancreatic cancer patients. Furthermore, we treated 13 patients with metastatic or locally advanced pancreatic cancer using autologous RetroNectin-activated CIK cells (R-CIK cells) alone or in combination with chemotherapy. Compared with only CD3 activated CIK cells (OKT-CIK cells), R-CIK cells showed stronger and faster proliferative ability, with a lower ratio of spontaneous apoptosis. Moreover, this ability continued after IL-2 was withdrawn from the culture system. R-CIK cells could also secrete higher levels of IL-2 and lower levels of IL-4 and IL-5 versus OKT-CIK cells. There was no difference between OKT-CIK and R-CIK cells in cytotoxic ability against lymphoma cell line K562. In patients who received auto-R-CIK cell infusion therapy, the overall objective response rate was 23.1%. Median survival time (mOS) after first R-CIK cell infusion was 10.57 months; the 1-year survival rate was 38.5%. No serious toxicity was associated with R-CIK cell infusion. In conclusion, RetroNectin may enhance antitumor activity of CIK cells: it is safe for use in treating pancreatic cancer.