Interleukin-21 as an adjuvant in cancer immunotherapy: Current advances and future directions

Immunotherapy has revolutionized cancer treatment. However, it's well-recognized that a considerable proportion of patients fail to benefit from immunotherapy, and to improve immunotherapy response is clinically urgent. Insufficient immune infiltration and immunosuppressive tumor microenvironments (TME) are main contributors to immunotherapy resistance. Thus sustaining functional self-renewal capacity for immune cells and subverting immune-suppressive signals are potential strategies for boosting the efficacy of immunotherapy. Interleukin-21 (IL-21), a crucial cytokine, which could enhance cytotoxic function of immune cells and reduces immunosuppressive cells enrichment in TME, shows promising orientations as an immunoadjuvant in tumor immunotherapy. This review focuses on IL-21 in cancer treatment, including function and mechanisms of IL-21, preclinical and clinical studies, and future directions for IL-21-assisted therapies.

Synergistic effect of combining sunitinib with a peptide-based vaccine in cancer treatment after microenvironment remodeling

Although it has proven difficult to demonstrate the clinical efficacy of therapeutic vaccination as a monotherapy in advanced cancers, its combination with an immunomodulatory treatment to reduce intra-tumor immunosuppression and improve vaccine efficacy is a very promising strategy. In this context, we are studying the combination of a vaccine composed of peptides of the tumor antigen survivin (SVX vaccine) with the anti-angiogenic agent sunitinib in a colorectal carcinoma model. To this end, we have been focusing on administration scheduling and have highlighted a therapeutic synergy between SVX vaccine and sunitinib when the vaccine was administered at the end of anti-angiogenic treatment. In this setting, a prolonged control of tumor growth associated with an important percentage of complete tumor regression was observed. Studying the remodeling induced by each therapy on the immunological and angiogenic tumor microenvironment over time we observed, during sunitinib treatment, a transient increase in polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and a decrease in NK cells in the tumor microenvironment. In contrast, after sunitinib treatment was stopped, a decrease in PMN-MDSC populations has been observed in the tumor, associated with an increase in NK cells, pericyte coverage of tumor vessels and CD8⁺ T cell population and functionality. In conclusion, sunitinib treatment results in the promotion of an immune-favorable tumor microenvironment that can guide the optimal sequence of vaccine and anti-angiogenic combination to reinforce their synergy.

Sorafenib inhibits interferon production by plasmacytoid dendritic cells in hepatocellular carcinoma

BACKGROUND

Sorafenib is a multi-kinase inhibitor that shows antitumor activity in advanced hepatocellular carcinoma. Sorafenib exerts a regulatory effect on immune cells, including T cells, natural killer cells and dendritic cells. Studies have shown that plasmacytoid dendritic cells (pDCs) are functionally impaired in cancer tissues or produce low type I interferon alpha (IFNα) in cancer microenvironments. However, the effects of sorafenib on the function of pDCs have not been evaluated in detail.

METHODS

Normal and patient PBMCs were stimulated with CpG-A to evaluate IFNα production with Flow cytometry and ELISA.

RESULT

We analyzed the production of IFNα by PBMCs in patients with advanced HCC under sorafenib treatment. We found that sorafenib-treated HCC patients produced less IFNα than untreated patients. Furthermore, we demonstrated that sorafenib suppressed the production of IFNα by PBMCs or pDCs from heathy donors in a concentration-dependent manner.

CONCLUSION

Sorafenib suppressed pDCs function. Given that sorafenib is a currently recommended targeted therapeutic agent against cancer, our results suggest that its immunosuppressive effect on pDCs should be considered during treatment.

Modulation of the tumour microenvironment in hepatocellular carcinoma by tyrosine kinase inhibitors: from modulation to combination therapy targeting the microenvironment

Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide. Tyrosine kinase inhibitors (TKIs) remain the backbone of systematic therapy for advanced hepatocellular carcinoma. Sorafenib and lenvatinib are currently approved as first-line therapeutic drugs, and regorafenib and cabozantinib are applied as second-line treatments. With inhibition of angiogenesis as the main target, TKIs exert a profound effect on the tumour microenvironment (TME). The TME is a complex mixture of cellular and noncellular components surrounding the tumour mass, and is associated with tumour progression partially through the epithelial-mesenchymal transition. Specifically, the TME of HCC is characterized by profound extracellular matrix remodelling and an immunosuppressive microenvironment. The purpose of this review is to provide a summary of TME remodelling mediated by four Food and Drug Administration approved TKIs in HCC and thus summarize the rationale and potential targets for combination therapy. The modulatory effect of TKIs on the TME of HCC was reported to enhance the antitumour effect of TKIs through pyroptosis of macrophages and subsequent natural killer cell activation, T cell activation, regulatory T cell reduction in HCC. Meanwhile, TKIs also induce drug resistance via M2 polarization and accumulation, recruitment of tumour-associated neutrophils, and induction of the epithelial-mesenchymal transition. In conclusion, the effect of TKIs on TME can enhance its antitumour effect, but might also partially contribute to the drug resistance that hinders the progression of TKIs as treatment for HCC. Additionally, the effect of TKIs also provides the rationale for combination therapy, including combining TKIs with immune checkpoint inhibitors, to facilitate increased drug efficacy of TKIs.

The effects of Sorafenib and Natural killer cell co-injection in combinational treatment of hepatocellular carcinoma; an in vivo approach

BACKGROUND

Natural killer cells (NKC) and Sorafenib (Sor) are two important agents for the treatment of hepatocellular carcinoma (HCC). Over the past decade, the interaction of Sor and NKC against HCC has been widely challenging. This study aimed to assess the efficacy of NKC & Sor for the treatment of HCC in vivo.

METHODS

Subcutaneous xenograft models of HCC were established in nude mice. For safety assessment of treatment, the kidney and liver functions were analyzed. Paraffin embedded tumor sections were histopathologically studied and immunohistochemistry (IHC) tests were done to evaluate the angiogenesis (CD34) and proliferation (Ki67) indexes. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to identify the tumor cells undergoing apoptosis. The serum levels of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were measured by enzyme-linked immunosorbent assay (ELISA) and expression levels of major inflammatory cytokines and cytoplasmic granules in xenograft HCC were quantified using real-time PCR.

RESULTS

NKC & Sor significantly inhibited necrosis and apoptosis in tumor cells and increased angiogenesis and proliferation of HCC compared to the monotherapy of NKC or Sor alone. The serum levels of TNF-α, IFN-γ as well as the expression levels of TNF-α, IFN-γ, interleukins (ILs)-1, 6, 10, granzyme-B and perforin in the xenograft HCC tissues of the treated mice with NKC & Sor were significantly lower than those of treated with NKC or Sor alone.

CONCLUSION

Therapy with the specific dosage of NKC & Sor could not inhibit the HCC xenograft growth rate through a synergistic effect in a mouse model of HCC.

Combination of molecularly targeted therapies and immune checkpoint inhibitors in the new era of unresectable hepatocellular carcinoma treatment

Multikinase inhibitors (MKIs) have been the only first-line treatment for advanced hepatocellular carcinoma (HCC) for more than a decade, until the approval of immune checkpoint inhibitors (ICIs). Moreover, the combination regimen of atezolizumab (anti-programmed cell death protein ligand 1 antibody) plus bevacizumab (anti-vascular endothelial growth factor monoclonal antibody) has recently been demonstrated to have superior efficacy when compared with sorafenib monotherapy. The remarkable efficacy has made this combination therapy the new standard treatment for advanced HCC. In addition to MKIs, many other molecularly targeted therapies are under investigation, some of which have shown promising results. Therefore, in the era of immuno-oncology, there is a significant rationale for testing the combinations of molecularly targeted therapies and ICIs. Indeed, numerous preclinical and clinical studies have shown the synergic antitumor efficacy of such combinations. In this review, we aim to summarize the current knowledge on the combination of molecularly targeted therapies and immune checkpoint therapies for HCC from both preclinical and clinical perspectives.

Natural Killer Cells and Anti-Cancer Therapies: Reciprocal Effects on Immune Function and Therapeutic Response

Simple Summary

Natural Killer (NK) cells are innate lymphocytes that play an important role in the immune response against cancer. Their activity is controlled by a balance of inhibitory and activating receptors, which in cancer can be skewed to favor their suppression in support of immune escape. It is therefore imperative to find ways to optimize their antitumor functionality. In this review, we explore and discuss how their activity influences, or even mediates, the efficacy of various anti-cancer therapies and, vice versa, how their activity can be affected by these therapies. Knowledge of the mechanisms underlying these observations could provide rationales for combining anti-cancer treatments with strategies enhancing NK cell function in order to improve their therapeutic efficacy.

Abstract

Natural Killer (NK) cells are innate immune cells with the unique ability to recognize and kill virus-infected and cancer cells without prior immune sensitization. Due to their expression of the Fc receptor CD16, effector NK cells can kill tumor cells through antibody-dependent cytotoxicity, making them relevant players in antibody-based cancer therapies. The role of NK cells in other approved and experimental anti-cancer therapies is more elusive. Here, we review the possible role of NK cells in the efficacy of various anti-tumor therapies, including radiotherapy, chemotherapy, and immunotherapy, as well as the impact of these therapies on NK cell function.

NK cells sense tumors, course of disease and treatments: Consequences for NK-based therapies

The recent findings on NK activation indicate that these cells are important antitumor effectors. NK cells participate in the graft-vs.-leukemia effect to control the relapse in leukemic patients transplanted with allogeneic hematopoietic stem cells. In various tumors, correlation between NK cell infiltrates and prognosis were reported. However, tumor-infiltrating NK cells are yet poorly characterized. We here summarize our results and the recent studies of the literature on tumor-infiltrating NK cells, and discuss the impact of these novel insights into NK cell responses against tumors for the design of NK cell-based therapies.

Harnessing Natural Killer Cell Function for Genitourinary Cancers

Natural killer (NK) cells are potently cytolytic innate lymphocytes involved in the immune surveillance of tumors and virally infected cells. Although much progress has been made in manipulating the ability of T cells to recognize and eliminate tumors, a comprehensive understanding of NK-cell infiltration into solid tumors, and their amenability to immunomodulation, remains incomplete. This article discusses recent studies showing that urologic tumors are infiltrated by NK cells and that these NK cells are often dysfunctional, but that strategies interfering with inhibitory axes have significant potential to alleviate this dysfunction.

NK Cell-Based Immunotherapy in Renal Cell Carcinoma

Natural killer (NK) cells are cytotoxic lymphocytes that are able to kill tumor cells without prior sensitization. It has been shown that NK cells play a pivotal role in a variety of cancers, highlighting their relevance in tumor immunosurveillance. NK cell infiltration has been reported in renal cell carcinoma (RCC), the most frequent kidney cancer in adults, and their presence has been associated with patients’ survival. However, the role of NK cells in this disease is not yet fully understood. In this review, we summarize the biology of NK cells and the mechanisms through which they are able to recognize and kill tumor cells. Furthermore, we discuss the role that NK cells play in renal cell carcinoma, and review current strategies that are being used to boost and exploit their cytotoxic capabilities.

Sorafenib may enhance antitumour efficacy in hepatocellular carcinoma patients by modulating the proportions and functions of natural killer cells

Dysfunction of natural killer (NK) cells is associated with poor prognosis in hepatocellular carcinoma (HCC). We explored the phenotypic and functional characteristics of peripheral blood NK cells in HCC patients following sorafenib treatment.Peripheral blood samples were collected from 60 HCC patients in a single centre (2015~2017) and 45 healthy donors. The percentage and cytoplasmic granule production of NK cells were analysed. Subset proportions were evaluated for their associations with the modified Response Evaluation Criteria in Solid Tumors (mRECIST), time to progression, and median overall survival (OS).Compared with baseline, the percentages of total and CD56^dimCD16⁺ NK cells increased after two months of treatment, while the percentage of CD56^brightCD16^- NK cells decreased, leading to a dramatically reduced ratio of CD56^bright and CD56^dim NK cells (ratio^bri/dim). Patients with low ratio^bri/dim exhibited better mRECIST responses and longer median OS than those with high ratio^bri/dim. The expression levels of granzyme B and perforin in total NK cells and in both subsets of cells were increased after treatment.This study showed that sorafenib could affect the proportions and functions of peripheral CD56^brightCD16^- and CD56^dimCD16⁺ NK cells, which was associated with the outcomes including OS of HCC patients.

Sorafenib Induces Pyroptosis in Macrophages and Triggers Natural Killer Cell-Mediated Cytotoxicity Against Hepatocellular Carcinoma

Antiangiogenic and cytotoxic effects are considered the principal mechanisms of action of sorafenib, a multitarget kinase inhibitor approved for the treatment of hepatocellular carcinoma (HCC). We report that sorafenib also acts through direct immune modulation, indispensable for its antitumor activity. In vivo cell depletion experiments in two orthotopic HCC mouse models as well as in vitro analysis identified macrophages (MΦ) as the key mediators of the antitumoral effect and demonstrate a strong interdependency of MΦ and natural killer (NK) cells for efficient tumor cell killing. Caspase 1 analysis in sorafenib-treated MΦ revealed an induction of pyroptosis. As a result, cytotoxic NK cells become activated when cocultured with sorafenib-treated MΦ, leading to tumor cell death. In addition, sorafenib was found to down-regulate major histocompatibility complex class I expression of tumor cells, which may reduce the tumor responsiveness to immune checkpoint therapies and favor NK-cell response. In vivo cytokine blocking revealed that sorafenib efficacy is abrogated after inhibition of interleukins 1B and 18. Conclusion: We report an immunomodulatory mechanism of sorafenib involving MΦ pyroptosis and unleashing of an NK-cell response that sets it apart from other spectrum kinase inhibitors as a promising immunotherapy combination partner for the treatment of HCC.

RNAi-based small molecule repositioning reveals clinically approved urea-based kinase inhibitors as broadly active antivirals

Influenza viruses (IVs) tend to rapidly develop resistance to virus-directed vaccines and common antivirals targeting pathogen determinants, but novel host-directed approaches might preclude resistance development. To identify the most promising cellular targets for a host-directed approach against influenza, we performed a comparative small interfering RNA (siRNA) loss-of-function screen of IV replication in A549 cells. Analysis of four different IV strains including a highly pathogenic avian H5N1 strain, an influenza B virus (IBV) and two human influenza A viruses (IAVs) revealed 133 genes required by all four IV strains. According to gene enrichment analyses, these strain-independent host genes were particularly enriched for nucleocytoplasmic trafficking. In addition, 360 strain-specific genes were identified with distinct patterns of usage for IAVs versus IBV and human versus avian IVs. The strain-independent host genes served to define 43 experimental and otherwise clinically approved drugs, targeting reportedly fourteen of the encoded host factors. Amongst the approved drugs, the urea-based kinase inhibitors (UBKIs) regorafenib and sorafenib exhibited a superior therapeutic window of high IV antiviral activity and low cytotoxicity. Both UBKIs appeared to block a cell signaling pathway involved in IV replication after internalization, yet prior to vRNP uncoating. Interestingly, both compounds were active also against unrelated viruses including cowpox virus (CPXV), hantavirus (HTV), herpes simplex virus 1 (HSV1) and vesicular stomatitis virus (VSV) and showed antiviral efficacy in human primary respiratory cells. An in vitro resistance development analysis for regorafenib failed to detect IV resistance development against this drug. Taken together, the otherwise clinically approved UBKIs regorafenib and sorafenib possess high and broad-spectrum antiviral activity along with substantial robustness against resistance development and thus constitute attractive host-directed drug candidates against a range of viral infections including influenza.

Conventional medications against influenza infections, including vaccination and antiviral drug therapy, are targeted against viral determinants–an approach collectively referred to as pathogen-directed. However, influenza viruses mutate fast and quickly develop resistance to these pathogen-directed treatments. An alternative, yet not well established, is to block host cellular molecules required by the virus to successfully multiply. Such a host-directed approach is anticipated to be more robust against the development of drug resistance. This notion is founded on the different modes of action of the two principal approaches: Virus-directed therapeutics target the virus itself. Thus, just a single mutation could abrogate sensitivity to a virus-directed therapeutic. In contrast, it is unlikely that viruses can easily circumvent a pharmacological blockage of a cellular factor by means of just a few mutations. Instead, the virus needs to either exploit an immediate parallel cellular pathway or adjust its replication cycle to a different cellular factor–the latter being a process likely to require multiple mutations, if possible at all. To identify the most promising targets for a host-directed therapy, we performed a small interfering RNA (siRNA) screen with four different influenza virus strains using a lung epithelial cell line. Subsequently, we tested a series of drugs, specific for the products of the genes that are required for replication of all four influenza virus strains tested. Regorafenib and sorafenib, two chemically related urea-based kinase inhibitors already clinically approved for cancer treatment, turned out to be effective inhibitors of all influenza viruses and displayed low cytotoxicity. These drugs blocked viral replication at an early stage of the life cycle not only in cell lines but also in human primary respiratory cells. Moreover, these drugs exhibited high efficacy even against unrelated viruses. In addition, no development of resistance was observed against regorafenib, which was used in an in vitro assay representatively of urea-based kinase inhibitors. Our results suggest that regorafenib and sorafenib are promising drug candidates for a host-directed therapy of influenza and other viral infections.

Mutated Von Hippel-Lindau-renal cell carcinoma (RCC) promotes patients specific natural killer (NK) cytotoxicity

Background

Previous evidence demonstrated that restoration of wild type VHL in human renal cancer cells decreased in vitro NK susceptibility. To investigate on the role of tumoral VHL status versus NK capability in renal cancer patients, 51 RCC patients were characterized for VHL mutational status and NK function.

Methods

VHL mutational status was determined by direct DNA sequencing on tumor tissue. NK cytotoxicity was measured against specific target cells K562, VHL-wild type (CAKI-1) and VHL-mutated (A498) human renal cancer cells through externalization of CD107a and IFN-γ production. Activating NK receptors, NKp30, NKp44, NKp46, NKG2D, DNAM-1, NCAM-1 and FcγRIIIa were evaluated through quantitative RT-PCR. RCC tumoral Tregs were characterized as CD4⁺CD25⁺CD127^lowFoxp3⁺ and Treg function was evaluated as inhibition of T-effector proliferation.

Results

VHL mutations were detected in 26/55 (47%) RCC patients. IL-2 activated whole-blood samples (28 VHL-WT-RCC and 23 VHL-MUT-RCC) were evaluated for NK cytotoxicity toward human renal cancer cells A498, VHL-MUT and CAKI-1, VHL-WT. Efficient NK degranulation and increase in IFN-γ production was detected when IL-2 activated whole-blood from VHL-MUT-RCC patients were tested toward A498 as compared to CAKI-1 cells (CD107a⁺NK: 7 ± 2% vs 1 ± 0.41%, p = 0.015; IFN-γ⁺NK: 6.26 ± 3.4% vs 1.78 ± 0.9% respectively). In addition, IL-2 activated NKs induced higher CD107a exposure in the presence of RCC autologous tumor cells or A498 as compared to SN12C (average CD107a⁺NK: 4.7 and 2.7% vs 0.3% respectively at 10E:1 T ratio).

VHL-MUT-RCC tumors were NKp46⁺ cells infiltrated and expressed high NKp30 and NKp46 receptors as compared to VHL-WT-RCC tumors. A significant lower number of Tregs was detected in the tumor microenvironment of 13 VHL-MUT-RCC as compared to 13 VHL-WT-RCC tumors (1.84 ± 0.36% vs 3.79 ± 0.74% respectively, p = 0.04). Tregs isolated from VHL-MUT-RCC patients were less suppressive of patients T effector proliferation compared to Tregs from VHL-WT-RCC patients (Teff proliferation: 6.7 ± 3.9% vs 2.8 ± 1.1%).

Conclusions

VHL tumoral mutations improve NKs effectiveness in RCC patients and need to be considered in the evaluation of immune response. Moreover therapeutic strategies designed to target NK cells could be beneficial in VHL-mutated-RCCs alone or in association with immune checkpoints inhibitors.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0952-7) contains supplementary material, which is available to authorized users.

Tumor hypoxia directed multimodal nanotherapy for overcoming drug resistance in renal cell carcinoma and reprogramming macrophages

Drug resistance is one of the significant clinical burden in renal cell carcinoma (RCC). The development of drug resistance is attributed to many factors, including impairment of apoptosis, elevation of carbonic anhydrase IX (CA IX, a marker of tumor hypoxia), and infiltration of tumorigenic immune cells. To alleviate the drug resistance, we have used Sorafenib (Sor) in combination with tumor hypoxia directed nanoparticle (NP) loaded with a new class of apoptosis inducer, CFM 4.16 (C4.16), namely CA IX-C4.16. The NP is designed to selectively deliver the payload to the hypoxic tumor (core), provoke superior cell death in parental (WT) and Everolimus-resistant (Evr-res) RCC and selectively downmodulate tumorigenic M2-macrophage. Copper-free 'click' chemistry was utilized for conjugating SMA-TPGS with Acetazolamide (ATZ, a CA IX-specific targeting ligand). The NP was further tagged with a clinically approved NIR dye (S0456) for evaluating hypoxic tumor core penetration and organ distribution. Imaging of tumor spheroid treated with NIR dye-labeled CA IX-SMA-TPGS revealed remarkable tumor core penetration that was modulated by CA IX-mediated targeting in hypoxic-A498 RCC cells. The significant cell killing effect with synergistic combination index (CI) of CA IX-C4.16 and Sor treatment suggests efficient reversal of Evr-resistance in A498 cells. The CA IX directed nanoplatform in combination with Sor has shown multiple benefits in overcoming drug resistance through (i) inhibition of p-AKT, (ii) upregulation of tumoricidal M1 macrophages resulting in induction of caspase 3/7 mediated apoptosis of Evr-res A498 cells in macrophage-RCC co-culturing condition, (iii) significant in vitro and in vivo Evr-res A498 tumor growth inhibition as compared to individual therapy, and (iv) untraceable liver and kidney toxicity in mice. Near-infrared (NIR) imaging of CA IX-SMA-TPGS-S0456 in Evr-res A498 RCC model exhibited significant accumulation of CA IX-oligomer in tumor core with >3-fold higher tumor uptake as compared to control. In conclusion, this proof-of-concept study demonstrates versatile tumor hypoxia directed nanoplatform that can work in synergy with existing drugs for reversing drug-resistance in RCC accompanied with re-education of tumor-associated macrophages, that could be applied universally for several hypoxic tumors.

Combinational immune-cell therapy of natural killer cells and sorafenib for advanced hepatocellular carcinoma: a review

Background

High prevalence of hepatocellular carcinoma (HCC) and typically poor prognosis of this disease that lead to late stage diagnosis when potentially curative therapies are least effective; therefore, development of an effective and systematic treatment is an urgent requirement.

Main body

In this review, several current treatments for HCC patients and their advantages or disadvantages were summarized. Moreover, various recent preclinical and clinical studies about the performances of "two efficient agents, sorafenib or natural killer (NK) cells", against HCC cells were investigated. In addition, the focus this review was on the chemo-immunotherapy approach, correlation between sorafenib and NK cells and their effects on the performance of each other for better suppression of HCC.

Conclusion

It was concluded that combinational therapy with sorafenib and NK cells might improve the outcome of applied therapeutic approaches for HCC patients. Finally, it was also concluded that interaction between sorafenib and NK cells is dose and time dependent, therefore, a careful dose and time optimizing is necessary for development of a combinational immune-cell therapy.

Angiogenic and immunological pathways in metastatic renal cell carcinoma: A counteracting paradigm or two faces of the same medal? The GIANUS Review

In the so-called "antiangiogenic era" of recent years, a number of targeted therapies have been approved for the treatment of metastatic renal cell carcinoma (mRCC). Emerging information about the immunological features of mRCC and the immunomodulating properties of antiangiogenic agents, one of the standard treatments for mRCC, indicates that a more rational design of potentially synergistic combinations should be pursued. Indeed, immunotherapy has undergone a resurgence in clinical practice. In this narrative review, we discuss the immunological features of mRCC and the potential interactions that antiangiogenic agents may also exert on host immunity and tumor immunogenicity, possibly working on both sides of this complex cross-talk. Hence, the recall to Gianus, the ancient two-faced Roman God who was looking both at the future and the past. Treatment strategies will be also critically discussed.

Sorafenib paradoxically activates the RAS/RAF/ERK pathway in polyclonal human NK cells during expansion and thereby enhances effector functions in a dose- and time-dependent manner

Natural killer (NK) cells play a major role in host immunity against leukaemia and lymphoma. However, clinical trials applying NK cells have not been as efficient as hoped for. Patients treated with rapidly accelerated fibrosarcoma (RAF) inhibitors exhibit increased tumour infiltration by immune cells, suggesting that a combination of RAF inhibitors with immunotherapy might be beneficial. As mitogen-activated protein kinases (MAPKs) such as raf-1 proto-oncogene, serine/threonine kinase (CRAF) regulate NK cell functions, we performed an in-vitro investigation on the potential of clinically relevant short-acting tyrosine kinase inhibitors (TKIs) as potential adjuvants for NK cell therapy: NK cells from healthy human blood donors were thus treated with sorafenib, sunitinib or the pan-RAF inhibitor ZM336372 during ex-vivo expansion. Functional outcomes assessed after washout of the drugs included cytokine production, degranulation, cytotoxicity, apoptosis induction and signal transduction with/without target cell contact. Paradoxically, sorafenib enhanced NK cell effector functions in a time- and dose-dependent manner by raising the steady-state activation level. Of note, this did not lead to NK cell exhaustion, but enhanced activity against target cells such as K562 or Daudis mediated via the RAS/RAF/extracellular-regulated kinase (ERK) pathway, but not via protein kinase B (AKT). Our data will pave the path to develop a rationale for the considered use of RAF inhibitors such as sorafenib for pre-activation in NK cell-based adoptive immune therapy.

Combination of sorafenib and cytokine-induced killer cells in metastatic renal cell carcinoma: a potential regimen

Metastatic renal cell carcinoma (MRCC) exhibits primary resistance to both chemotherapy and radiotherapy. As an immunogenic cancer, MRCC is relatively sensitive to immunotherapy such as that with cytokines, immune checkpoint inhibitors and adoptive T-cell therapy. In addition, many targeted agents developed over the past decade exhibit greater efficacy than cytokines and have become the standard first-line therapy for MRCC. Several preclinical studies have shown that the targeted agent sorafenib possesses an immunomodulation function and may be suitable for combination with immunotherapy. Here, combinatorial therapy consisting of sorafenib and cytokine-induced killer cell immunotherapy was administered to an MRCC patient resulting in a synergistic effect without serious adverse effects. These results suggest a potential combinatorial regimen for MRCC patients.

Clinical and kinomic analysis identifies peripheral blood mononuclear cells as a potential pharmacodynamic biomarker in metastatic renal cell carcinoma patients treated with sunitinib

Background

Sunitinib is a protein tyrosine kinase (PTK) inhibitor that has immune-modulating properties. In this context, peripheral blood mononuclear cells (PBMC), mainly constituted by lymphocytes, could be a perfect surrogate tissue for identifying and assaying pharmacodynamic biomarkers of sunitinib. In this study, we investigated the changes in lymphocytes count as pharmacodynamic biomarker in metastatic renal cell carcinoma (mRCC) patients under sunitinib therapy. Thereafter, we studied the ex vivo effect of sunitinib and SU12262 (active metabolite) on PBMC from naïve mRCC patients using a high throughput kinomic profiling method.

Methods

The prognostic value of total lymphocytes count between Day 0 and Day 21 (expressed as a ratio D21/D0) was retrospectively investigated in 88 mRCC patients under sunitinib therapy. PTK PamChip^® microarrays were used to explore prospectively the ex vivo effect of sunitinib and SU12662 on PTK activity in PBMC from 21 naïve mRCC patients.

Results

In this retrospective study, D21/D0 lymphocytes ratio (Hazard Ratio, 1.83; CI95%, 1.24-2.71; p=0.0023) was independently associated with PFS. Interestingly, kinomic analysis showed that D21/D0 lymphocytes ratio and Heng prognostic model was statistically associated with the ex vivo sunitinib and SU12662 effect in PBMC.

Conclusion

The present study highlights that D21/D0 total lymphocytes ratio could be a promising pharmacodynamic biomarker in mRCC patients treated with sunitinib. Additionally, it paves the way to investigate the kinomic profile in PBMC as a prognostic factor in a larger cohort of mRCC patients under sunitinib therapy.

Harness the synergy between targeted therapy and immunotherapy: what have we learned and where are we headed?

Since the introduction of imatinib for the treatment of chronic myelogenous leukemia, several oncogenic mutations have been identified in various malignancies that can serve as targets for therapy. More recently, a deeper insight into the mechanism of antitumor immunity and tumor immunoevasion have facilitated the development of novel immunotherapy agents. Certain targeted agents have the ability of inhibiting tumor growth without causing severe lymphocytopenia and amplifying antitumor immune response by increasing tumor antigenicity, enhancing intratumoral T cell infiltration, and altering the tumor immune microenvironment, which provides a rationale for combining targeted therapy with immunotherapy. Targeted therapy can elicit dramatic responses in selected patients by interfering with the tumor-intrinsic driver mutations. But in most cases, resistance will occur over a relatively short period of time. In contrast, immunotherapy can yield durable, albeit generally mild, responses in several tumor types via unleashing host antitumor immunity. Thus, combination approaches might be able to induce a rapid tumor regression and a prolonged duration of response. We examine the available evidence regarding immune effects of targeted therapy, and review preclinical and clinical studies on the combination of targeted therapy and immunotherapy for cancer treatment. Furthermore, we discuss challenges of the combined therapy and highlight the need for continued translational research.

Sunitinib does not impair natural killer cell function in patients with renal cell carcinoma

Although the available treatment options have expanded, the survival of patients with metastatic renal cell carcinoma (RCC) remains poor. As patients with RCC lack responsiveness to chemotherapy or radiation, therapeutic options predominantly include surgical interventions and immunomodulatory approaches, including the administration of tyrosine kinase inhibitors (TKIs) such as sunitinib. Natural killer (NK) cells have been reported to be key players in TKI-mediated off-target effects on the immune system. However, only limited information is available regarding the possible impact of sunitinib on the function of NK cells of individual patients. The present study reports on the immunomonitoring results of three patients with metastatic RCC who underwent sunitinib treatment. These results were compared with age-matched, healthy controls in terms of the immune status of T, B and NK cells, focusing on functional in vitro analyses of NK cells. In all three patients, NK cell number, subset distribution and function, as measured by cluster of differentiation 107a degranulation, did not exhibit any significant alterations as a result of sunitinib treatment. These results indicate that sunitinib does not negatively affect NK cell function, which supports the pursuit of therapeutic modalities that combine immunomodulation and NK cell-stimulating approaches.

Tyrosine kinase inhibitors reprogramming immunity in renal cell carcinoma: rethinking cancer immunotherapy

The immune system regulates angiogenesis in cancer by way of both pro- and antiangiogenic activities. A bidirectional link between angiogenesis and the immune system has been clearly demonstrated. Most antiangiogenic molecules do not inhibit only VEGF signaling pathways but also other pathways which may affect immune system. Understanding of the role of these pathways in the regulation of immunosuppressive mechanisms by way of specific inhibitors is growing. Renal cell carcinoma (RCC) is an immunogenic tumor in which angiogenesis and immunosuppression work hand in hand, and its growth is associated with impaired antitumor immunity. Given the antitumor activity of selected TKIs in metastatic RCC (mRCC), it seems relevant to assess their effect on the immune system. The confirmation that TKIs improve cell cytokine response in mRCC provides a basis for the rational combination and sequential treatment of TKIs and immunotherapy.

Immunomodulatory Activity of VEGF in Cancer

The ability of tumor cells to escape tumor immunosurveillance contributes to cancer development. Factors produced in the tumor microenvironment create "tolerizing" conditions and thereby help the tumor to evade antitumoral immune responses. VEGF-A, already known for its major role in tumor vessel growth (neoangiogenesis), was recently identified as a key factor in tumor-induced immunosuppression. In particular, VEGF-A fosters the proliferation of immunosuppressive cells, limits T-cell recruitment into tumors, and promotes T-cell exhaustion. Antiangiogenic therapies have shown significant efficacy in patients with a variety of solid tumors, preventing tumor progression by limiting tumor-induced angiogenesis. VEGF-targeting therapies have also been shown to modulate the tumor-induced immunosuppressive microenvironment, enhancing Th1-type T-cell responses and increasing tumor infiltration by T cells. The immunomodulatory properties of VEGF-targeting therapies open up new perspectives for cancer treatment, especially through strategies combining antiangiogenic drugs with immunotherapy. Preclinical models and early clinical studies of these combined approaches have given promising results.

Small-molecule inhibitor sorafenib regulates immunoreactions by inducing survival and differentiation of bone marrow cells

Sorafenib has been used for the treatment of liver cancer. However, its clinical impact on human immunity system remains poorly known. Our previous study has shown that sorafenib modulates immunosuppressive cell populations in murine liver cancer models. Here, we continue to report that low doses of sorafenib promotes the survival of murine bone marrow cells (BMCs) in a dose-dependent manner by up-regulating the anti-apoptotic protein survivin. Sorafenib induces differentiation of BMCs into suppressive dendritic cells that inhibit autologous T-cell proliferation and stimulate CD4+ T cells to express increased IL-1β, IL-2, IL-4, IL-10, IFN-γ and TNF-α, and reduced levels of IL-6 and CD25, which indicates that sorafenib-induced dendritic cells represent a distinct cellular subset with unique properties. Taken together, our findings suggest that in addition to its anticancer effects, sorafenib has an immunoregulatory property that is apparent at low doses.

Decreased NK-cell tumour immunosurveillance consequent to JAK inhibition enhances metastasis in breast cancer models

The JAK/STAT pathway is an attractive target for breast cancer therapy due to its frequent activation, and clinical trials evaluating JAK inhibitors (JAKi) in advanced breast cancer are ongoing. Using patient biopsies and preclinical models of breast cancer, we demonstrate that the JAK/STAT pathway is active in metastasis. Unexpectedly, blocking the pathway with JAKi enhances the metastatic burden in experimental and orthotopic models of breast cancer metastasis. We demonstrate that this prometastatic effect is due to the immunosuppressive activity of JAKi with ensuing impairment of NK-cell-mediated anti-tumour immunity. Furthermore, we show that immunostimulation with IL-15 overcomes the enhancing effect of JAKi on metastasis formation. Our findings highlight the importance of evaluating the effect of targeted therapy on the tumour environment. The impact of JAKi on NK cells and the potential value of immunostimulators to overcome the weakened tumour immunosurveillance, are worthwhile considering in the clinical setting of breast cancer.

JAK inhibitors are currently undergoing evaluation in clinical trials for advanced breast cancer. Here, the authors show that JAK pathway inhibition increases metastasis in mouse models of breast cancer by impairing NK anti-tumour activity and that these side effects can be overcome by addition of IL-15.

MiR-101 targets DUSP1 to regulate the TGF-β secretion in sorafenib inhibits macrophage-induced growth of hepatocarcinoma

Hepatocellular carcinoma (HCC)-associated macrophages accelerate tumor progression via growth factor release. Therefore, tumor-associated macrophages (TAMs)-initiated signaling cascades are potential therapeutic targets. To better understand anticancer effects of systemic HCC therapy, we studied sorafenib's effect on macrophage function, focusing on macrophage-related growth factor secretion. We found that dual specificity phosphatase 1 (DUSP1) is a direct target of miR-101. Transfection of miR-101 reduced DUSP1 induction in M2 macrophages and prolonged ERK1/2, p38 and JNK activation, whereas inhibition of miR-101 enhanced DUSP1 expression and decreased ERK1/2, p38 and JNK activation. miR-101 expression was decreased by sorafenib, and inhibition of PI3K/AKT blocked induction of miR-101 by LPS in M2 cells. M2 cells with greater TGF-β and CD206 mRNA expression compared to M1 cells had increased hepatoma growth, metastases and EMT. Sorafenib inhibited miR-101 expression and enhanced DUSP1 expression and lowered TGF-β and CD206 release in M2 cells, slowing macrophage-driven HCC. Our studies demonstrate miR-101 regulates macrophage innate immune responses to LPS via targeting DUSP1. Sorafenib alters macrophage polarization, reduces TGF-β driven cancer growth, metastases and EMT in vitro, and partially inhibits macrophage activation in vivo. Thus, macrophage modulation might explain the anticancer effects of sorafenib.

Expanded and Activated Natural Killer Cells for Immunotherapy of Hepatocellular Carcinoma

Viral infection of the liver is a major risk factor for hepatocellular carcinoma (HCC). Natural killer (NK) cells recognize virally infected and oncogenically transformed cells, suggesting a therapeutic role for NK-cell infusions in HCC. Using the K562-mb15-41BBL cell line as a stimulus, we obtained large numbers of activated NK cells from the peripheral blood of healthy donors. Expanded NK cells exerted remarkably high cytotoxicity against HCC cell lines, which was generally much higher than that of unstimulated or IL2-activated NK cells. In immunodeficient NOD/scid IL2RGnull mice engrafted with Hep3B, treatment with expanded NK cells markedly reduced tumor growth and improved overall survival. HCC cells exposed for 48 hours to 5 μmol/L of sorafenib, a kinase inhibitor currently used for HCC treatment, remained highly sensitive to expanded NK cells. HCC cell reductions of 39.2% to 53.8% caused by sorafenib in three cell lines further increased to 80.5% to 87.6% after 4 hours of culture with NK cells at a 1:1 effector-to-target ratio. NK-cell cytotoxicity persisted even in the presence of sorafenib. We found that NKG2D, an NK-cell-activating receptor, was an important mediator of anti-HCC activity. We therefore enhanced its signaling capacity with a chimeric NKG2D-CD3ζ-DAP10 receptor. This considerably increased the anti-HCC cytotoxicity of expanded NK cells in vitro and in immunodeficient mice. The NK expansion and activation method applied in this study has been adapted to clinical-grade conditions. Hence, these results warrant clinical testing of expanded NK-cell infusions in patients with HCC, possibly after genetic modification with NKG2D-CD3ζ-DAP10. Cancer Immunol Res; 4(7); 574-81. ©2016 AACR.

Enhancement of tumor cell susceptibility to natural killer cell activity through inhibition of the PI3K signaling pathway

Natural killer (NK) cells are the primary effectors of the innate immune response against virus-infected cells or cells that have undergone malignant transformation. NK cells recognize their targets through a complex array of activating and inhibitory receptors, which regulate the intensity of the effector response against individual target cells. However, many studies have shown that tumor cells can escape immune cell recognition through a variety of mechanisms, developing resistance to NK cell killing. Using a lentiviral shRNA library, we previously demonstrated that several common signaling pathways modulate susceptibility of tumor cells to NK cell activity. In this study, we focused on one of the genes (PI3KCB), identified in this genetic screen. The PI3KCB gene encodes an isoform of the catalytic subunit of PI3K called P110β. The PI3K pathway has been linked to diverse cellular functions, but has never been associated with susceptibility to NK cell activity. Gene silencing of PI3KCB resulted in increased susceptibility of several tumor cell lines to NK cell lytic activity and induced increased IFN-γ secretion by NK cells. Treatment of primary tumor cells with two different PI3K inhibitors also increased target cell susceptibility to NK cell activity. These effects are due, at least in part, to modulation of several activating and inhibitory ligands and appear to be correlated with PI3K signaling pathway inhibition. These findings identify a new and important role of PI3KCB in modulating tumor cell susceptibility to NK cells and open the way to future combined target immunotherapies.

Targeted scVEGF/(177)Lu radiopharmaceutical inhibits growth of metastases and can be effectively combined with chemotherapy

BACKGROUND

scVEGF/(177)Lu is a novel radiopharmaceutical targeted by recombinant single-chain (sc) derivative of vascular endothelial growth factor (VEGF) that binds to and is internalized by vascular endothelial growth factor receptors (VEGFR). scVEGF/(177)Lu potential as adjuvant and neoadjuvant anti-angiogenic therapy was assessed in metastatic and orthotopic mouse models of triple-negative breast cancer.

METHODS

Metastatic lesions in Balb/c mice were established by intracardiac injection of luciferase-expressing 4T1luc mouse breast carcinoma cells. Mice with metastatic lesions received single intravenous (i.v.) injection of well-tolerated dose of scVEGF/(177)Lu (7.4 MBq/mouse) at day 8 after 4T1luc cell injection. Primary orthotopic breast tumors in immunodeficient mice were established by injecting luciferase-expressing MDA231luc human breast carcinoma cells into mammary fat pad. Tumor-bearing mice were treated with single injections of scVEGF/(177)Lu (7.4 MBq/mouse, i.v), or liposomal doxorubicin (Doxil, 1 mg doxorubicin per kg, i.v.), or with a combination of Doxil and scVEGF/(177)Lu given at the same doses, but two hours apart. "Cold" scVEGF-targeting conjugate was included in controls and in Doxil alone group. The effects of treatments were defined by bioluminescent imaging (BLI), computed tomography (CT), computed microtomography (microCT), measurements of primary tumor growth, and immunohistochemical analysis.

RESULTS

In metastatic model, adjuvant treatment with scVEGF/(177)Lu decreased overall metastatic burden and improved survival. In orthotopic primary tumor model, a combination of Doxil and scVEGF/(177)Lu was more efficient in tumor growth inhibition than each treatment alone. scVEGF/(177)Lu treatment decreased immunostaining for VEGFR-1, VEGFR-2, and pro-tumorigenic M2-type macrophage marker CD206.

CONCLUSIONS

Selective targeting of VEGFR with well-tolerated doses of scVEGF/(177)Lu is effective in metastatic and primary breast cancer models and can be combined with chemotherapy. As high level of VEGFR expression is a common feature in a variety of cancers, targeted delivery of (177)Lu for specific receptor-mediated uptake warrants further exploration.

Natural killer (NK) cells and anti-tumor therapeutic mAb: unexplored interactions

Tumor-targeting mAb are widely used in the treatment of a variety of solid and hematopoietic tumors and represent the first immunotherapeutic approach successfully arrived to the clinic. Nevertheless, the role of distinct immune mechanisms in contributing to their therapeutic efficacy is not completely understood and may vary depending on tumor- or antigen/antibody-dependent characteristics. Availability of next-generation, engineered, tumor-targeting mAb, optimized in their capability to recruit selected immune effectors, re-enforces the need for a deeper understanding of the mechanisms underlying anti-tumor mAb functionality. NK cells participate with a major role to innate anti-tumor responses, by exerting cytotoxic activity and producing a vast array of cytokines. As the CD16 (low-affinity FcγRIIIA)-activating receptor is expressed on the majority of NK cells, its effector functions can be ideally recruited against therapeutic mAb-opsonized tumor cells. The exact role of NK cells in determining therapeutic efficacy of tumor-targeting mAb is still unclear and much sought after. This knowledge will be instrumental to design innovative combination schemes with newly validated immunomodulatory agents. We will summarize what is known about the role of NK cells in therapeutic anti-tumor mAb therapy, with particular emphasis on RTX chimeric anti-CD20 mAb, the first one used in clinical practice for treating B cell malignancies.

Present and Future of Allogeneic Natural Killer Cell Therapy

Natural killer (NK) cells are innate lymphocytes that are capable of eliminating tumor cells and are therefore used for cancer therapy. Although many early investigators used autologous NK cells, including lymphokine-activated killer cells, the clinical efficacies were not satisfactory. Meanwhile, human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation revealed the antitumor effect of allogeneic NK cells, and HLA-haploidentical, killer cell immunoglobulin-like receptor ligand-mismatched allogeneic NK cells are currently used for many protocols requiring NK cells. Moreover, allogeneic NK cells from non-HLA-related healthy donors have been recently used in cancer therapy. The use of allogeneic NK cells from non-HLA-related healthy donors allows the selection of donor NK cells with higher flexibility and to prepare expanded, cryopreserved NK cells for instant administration without delay for ex vivo expansion. In cancer therapy with allogeneic NK cells, optimal matching of donors and recipients is important to maximize the efficacy of the therapy. In this review, we summarize the present state of allogeneic NK cell therapy and its future directions.

The yin and yang of evasion and immune activation in HCC

Current systemic treatment options for patients with hepatocellular carcinoma (HCC) are limited to sorafenib. With the recent FDA approval of the second PD1-PD-L1 pathway inhibitor, immunotherapy has gained even more interest as a potential novel treatment option for patients with HCC. This is due not only because of the failure of other treatment approaches in the past, but also because immunological mechanisms have been shown to play an important role during tumor development, growth, and treatment. Here we present a review of immunological mechanisms in the liver relevant for tumor progression and treatment. We summarize our current knowledge on immune activating and immune suppressing mechanisms during tumor initiation, development, and treatment. We try to explain the paradox of how inflammatory responses in a setting of chronic infection promote tumor development, while the primary aim of immunotherapy is to activate immunity. Finally we summarize recent advances in addition to providing an outlook for the immunotherapy of HCC.

Current concepts of immune based treatments for patients with HCC: from basic science to novel treatment approaches

The recent approval of two immune checkpoint inhibitors for the treatment of malignant melanoma has sparked great interest by physicians and basic scientists searching for novel therapeutics for GI cancer. Chronic inflammation is recognised as a major risk factor for the development of hepatocellular carcinoma (HCC) and makes this type of cancer a potentially ideal target for an immune based treatment approach. Further evidence for a critical role of immune responses in patients with HCC is derived from the fact that immune signatures and profiles predict patients' outcome as well as the fact that tumour-induced spontaneous antitumour immunity can be detected. In addition ablative therapies can lead to changes in the number, phenotype and function of different immune cell subsets, which correlate with patients' survival. Various HCC-specific mouse models have been developed, which improve our understanding of hepatocarcinogenesis and tumour-immune cell interactions, and lead to the development of novel immune based treatment approaches, which are currently being evaluated in preclinical and in early clinical settings. Immune checkpoint blockade along with adoptive immune cell therapy and vaccine approaches are currently being evaluated either alone or in combination with other treatments. Here, we provide an overview for the rationale of immunotherapy in HCC, summarise ongoing studies and provide a perspective for immune based approaches in patients with HCC.

Therapeutic potential and challenges of natural killer cells in treatment of solid tumors

Natural killer (NK) cells are innate lymphoid cells that hold tremendous potential for effective immunotherapy for a broad range of cancers. Due to the mode of NK cell killing, requiring one-to-one target engagement and site-directed release of cytolytic granules, the therapeutic potential of NK cells has been most extensively explored in hematological malignancies. However, their ability to precisely kill antibody coated cells, cancer stem cells, and genotoxically altered cells, while maintaining tolerance to healthy cells makes them appealing therapeutic effectors for all cancer forms, including metastases. Due to their release of pro-inflammatory cytokines, NK cells may potently reverse the anti-inflammatory tumor microenvironment (TME) and augment adaptive immune responses by promoting differentiation, activation, and/or recruitment of accessory immune cells to sites of malignancy. Nevertheless, integrated and coordinated mechanisms of subversion of NK cell activity against the tumor and its microenvironment exist. Although our understanding of the receptor ligand interactions that regulate NK cell functionality has evolved remarkably, the diversity of ligands and receptors is complex, as is their mechanistic foundations in regulating NK cell function. In this article, we review the literature and highlight how the TME manipulates the NK cell phenotypes, genotypes, and tropism to evade tumor recognition and elimination. We discuss counter strategies that may be adopted to augment the efficacy of NK cell anti-tumor surveillance, the clinical trials that have been undertaken so far in solid malignancies, critically weighing the challenges and opportunities with this approach.

Infusions of allogeneic natural killer cells as cancer therapy

Natural killer (NK) cells are normal white blood cells capable of killing malignant cells without prior sensitization. Allogeneic NK cell infusions are attractive for cancer therapy because of non-cross-resistant mechanisms of action and minimal overlapping toxicities with standard cancer treatments. Although NK therapy is promising, many obstacles will need to be overcome, including insufficient cell numbers, failure of homing to tumor sites, effector dysfunction, exhaustion, and tumor cell evasion. Capitalizing on the wealth of knowledge generated by recent NK cell biology studies and the advancements in biotechnology, substantial progress has been made recently in improving therapeutic efficiency and reducing side effects. A multipronged strategy is essential, including immunogenetic-based donor selection, refined NK cell bioprocessing, and novel augmentation techniques, to improve NK function and to reduce tumor resistance. Although data from clinical trials are currently limited primarily to hematologic malignancies, broader applications to a wide spectrum of adult and pediatric cancers are under way. The unique properties of human NK cells open up a new arena of novel cell-based immunotherapy against cancers that are resistant to contemporary therapies.

Potential synergistic anti-tumor activity between lenalidomide and sorafenib in hepatocellular carcinoma

BACKGROUND AND AIM

The immune modulatory drug lenalidomide has shown promising anti-tumor activity in a clinical trial of patients with advanced hepatocellular carcinoma (HCC). The present study explored whether lenalidomide can enhance the anti-tumor activity of sorafenib, the standard molecular targeted therapy for HCC.

METHODS

The anti-tumor efficacy of single-agent or combination treatment was measured by change in tumor volume and animal survival using an orthotopic liver cancer model. Distribution of T-cell subpopulations in tumor-infiltrating lymphocytes (TILs) and splenocytes derived from tumor-implanted mice was measured by flow cytometry. Depletion of relevant T-cell subpopulations or cytokines was done by co-administration of relevant antibodies with study drug treatment. Tumor cell apoptosis and tumor angiogenesis were measured by transferase deoxytidyl uridine end labeling assay and immunohistochemical study, respectively.

RESULTS

Combination of sorafenib and lenalidomide produced significant synergistic anti-tumor efficacy in terms of tumor growth delay and animal survival. This synergistic effect was associated with a significant increase in interferon-γ expressing CD8(+) lymphocytes in TILs and a significantly higher number of granzyme- or perforin-expressing CD8(+) T cells, compared with vehicle- or single-agent treatment groups. Combination treatment significantly increased apoptotic tumor cells and vascular normalization in tumor tissue. The synergistic anti-tumor effect was abolished after CD8 depletion.

CONCLUSIONS

Lenalidomide can enhance the anti-tumor effects of sorafenib in HCC through its immune modulatory effects, and CD8(+) TILs play an important role in the anti-tumor synergism.

Kanglaite stimulates anticancer immune responses and inhibits HepG2 cell transplantation‑induced tumor growth

Previous studies revealed that Kanglaite (KLT) exhibits antitumor and immunomodulatory activities. In the present study, we show that KLT treatment stimulated the immune response by increasing the number of T cells and natural killer (NK) cells in the blood of hepatocellular carcinoma (HCC) patients. Experiments in tumor-bearing mice were further designed in order to explore the effects of KLT on the immune system and the underlying molecular mechanisms. The results showed that KLT improves the tumor cell transplantation-induced reduction in the serum level of the cytokines IFN‑γ and IL‑2, and rescues the levels of CD4+ T cells in host mice. These events enhanced the cytotoxic activities of natural killer and CD8+ T cells against the hepatic HepG2 cancer cells. KLT administration further increased the mRNA level of certain nuclear factor κB (NF‑κB)‑responsive genes in CD4+ cells. The chromatin immunoprecipitation assay showed that KLT increases the association of the NF-κB p65 subunit to the promoter regions of interleukin (IL)-2- and B-cell lymphoma (Bcl)-2-encoding genes in CD4+ T cells. Our study demonstrated that KLT is the main active ingredient of coix seed exhibiting anticancer and immunomodulatory properties. Induction of NF-κB‑mediated gene transcription in CD4+ T cells is involved in the immunomodulatory activity of KLT.

Dasatinib enhances migration of monocyte-derived dendritic cells by reducing phosphorylation of inhibitory immune receptors Siglec-9 and Siglec-3

The SRC family of kinases (SFKs) is crucial to malignant growth, but also important for signaling in immune cells such as dendritic cells (DCs). These specialized antigen-presenting cells are essential for inducing and boosting specific T-cell responses against pathogens and malignancies. Targeted therapy with SFK inhibitors holds great promise as a direct anti-cancer treatment, but potentially also as an indirect treatment via immunomodulation. Here, we investigated whether the BCR-ABL/SRC inhibitor dasatinib would modulate the major effector functions of DCs, especially their migration, a prerequisite to interaction with lymphocytes in secondary lymphoid organs. We report for the first time that dasatinib more than doubled the number of mature human monocyte-derived DCs (moDCs) migrating toward a CCL19 gradient despite unchanged CCR7 expression when used for pretreatment. These effects were caused by dephosphorylation of SFKs, as confirmed by the specific SFK inhibitor SRC inhibitor 1, leading to dephosphorylation of the inhibitory immunoreceptors Siglec-9 and Siglec-3. The specific blocking of the latter also enhanced migration and underlined the importance of these SFK-dependent receptor systems for migration of moDCs. Dasatinib hampered the secretion of interleukin-12 by moDCs at clinically relevant concentrations. In contrast, endocytosis or boosting of cytomegalovirus-specific CD8(+) T-cell responses remained unaltered when applying dasatinib-pretreated moDCs, in line with minor effects on the expression of co-stimulatory molecules essential for DC-T cell interaction. The induction of enhanced migration of moDCs may potentially be useful in chemo-immunotherapeutic applications. Thus, the use of dasatinib or blocking Siglec antibodies as adjuvants in this setting to induce stronger immune responses is worthy of further study.

Neoadjuvant sorafenib treatment of clear cell renal cell carcinoma and release of circulating tumor fragments

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is characterized by high constitutive vascular endothelial growth factor A (VEGF-A) production that induces a specific vascular phenotype. We previously reported that this phenotype may allow shedding of multicellular tumor fragments into the circulation, possibly contributing to the development of metastasis. Disruption of this phenotype through inhibition of VEGF signaling may therefore result in reduced shedding of tumor fragments and improved prognosis. To test this hypothesis, we investigated the effect of neoadjuvant sorafenib treatment on tumor cluster shedding.

PATIENTS AND METHODS

Patients with renal cancer (n = 10, of which 8 have ccRCC) received sorafenib for 4 weeks before tumor nephrectomy. The resection specimens were perfused, and the perfundate was examined for the presence of tumor clusters. Effects of the treatment on the tumor morphology and overall survival were investigated (follow-up of 2 years) and compared with a carefully matched control group.

RESULTS

Neoadjuvant sorafenib treatment induced extensive ischemic tumor necrosis and, as expected, destroyed the characteristic ccRCC vascular phenotype. In contrast to the expectation, vital groups of tumor cells with high proliferation indices were detected in postsurgical renal venous outflow in 75% of the cases. Overall survival of patients receiving neoadjuvant treatment was reduced compared to a control group, matched with regard to prognostic parameters.

CONCLUSIONS

These results suggest that neoadjuvant sorafenib therapy for ccRCC does not prevent shedding of tumor fragments. Although this is a nonrandomized study with a small patient group, our results suggest that neoadjuvant treatment may worsen survival through as yet undefined mechanisms.

Cancer-Induced Alterations of NK-Mediated Target Recognition: Current and Investigational Pharmacological Strategies Aiming at Restoring NK-Mediated Anti-Tumor Activity

Despite evidence of cancer immune-surveillance, which plays a key role in tumor rejection, cancer cells can escape immune recognition through different mechanisms. Thus, evasion to Natural killer (NK) cell-mediated anti-tumor activity is commonly described and is mediated by various mechanisms, mainly cancer cell-induced down-regulation of NK-activating receptors (NCRs, NKG2D, DNAM-1, and CD16) as well as up-regulation of inhibitory receptors (killer-cell immunoglobulin-like receptors, KIRs, NKG2A). Alterations of NK cells lead to an impaired recognition of tumor cells as well as a decreased ability to interact with immune cells. Alternatively, cancer cells downregulate expression of ligands for NK cell-activating receptors and up-regulate expression of the ligands for inhibitory receptors. A better knowledge of the extent and the mechanisms of these defects will allow developing pharmacological strategies to restore NK cell ability to recognize and lyse tumor cells. Combining conventional chemotherapy and immune modulation is a promising approach likely to improve clinical outcome in diverse neoplastic malignancies. Here, we overview experimental approaches as well as strategies already available in the clinics that restore NK cell functionality. Yet successful cancer therapies based on the manipulation of NK cell already have shown efficacy in the context of hematologic malignancies. Additionally, the ability of cytotoxic agents to increase susceptibility of tumors to NK cell lysis has been studied and may require improvement to maximize this effect. More recently, new strategies were developed to specifically restore NK cell phenotype or to stimulate NK cell functions. Overall, pharmacological immune modulation trends to be integrated in therapeutic strategies and should improve anti-tumor effects of conventional cancer therapy.

Recombinant interleukin-21 plus sorafenib for metastatic renal cell carcinoma: a phase 1/2 study

Background

Despite the positive impact of targeted therapies on metastatic renal cell carcinoma (mRCC), durable responses are infrequent and an unmet need exists for novel therapies with distinct mechanisms of action. We investigated the combination of recombinant Interleukin 21 (IL-21), a cytokine with unique immunostimulatory properties, plus sorafenib, a VEGFR tyrosine kinase inhibitor.

Methods

In this phase 1/2 study, 52 mRCC patients received outpatient treatment with oral sorafenib 400 mg twice daily plus intravenous IL-21 (10–50 mcg/kg) on days 1–5 and 15–19 of each 7-week treatment course. The safety, antitumor activity, pharmacokinetic and pharmacodynamic effects of the combination were evaluated.

Results

In phase 1 (n = 19), the maximum tolerated dose for IL-21 with the standard dose of sorafenib was determined to be 30 mcg/kg/day; grade 3 skin rash was the only dose-limiting toxicity. In phase 2, 33 previously-treated patients tolerated the combination therapy well with appropriate dose reductions; toxicities were mostly grade 1 or 2. The objective response rate was 21% and disease control rate was 82%. Two patients have durable responses that are ongoing, despite cessation of both IL-21 and sorafenib, at 41+ and 30+ months, respectively. The median progression-free survival in phase 2 was 5.6 months. The pharmacokinetic and pharmacodynamic properties of IL-21 appeared to be preserved in the presence of sorafenib.

Conclusion

IL-21 plus sorafenib has antitumor activity and acceptable safety in previously treated mRCC patients. IL-21 may represent a suitable immunotherapy in further exploration of combination strategies in mRCC.

Trial registration

ClinicalTrials.gov Identifier: NCT00389285

Role of natural and adaptive immunity in renal cell carcinoma response to VEGFR-TKIs and mTOR inhibitor

Angiogenesis and immunosuppression work hand-in-hand in the renal cell carcinoma (RCC) microenvironment. Tumor growth is associated with impaired antitumor immune response in RCC, which involves T cells, natural killer cells, dendritic cells (DCs) and macrophages. Vascular endothelial growth factor receptor (VEGFR), such as sorafenib, sunitinib, pazopanib and axitinib, and mammalian target of rapamycin (mTOR) inhibitors, such as temsirolimus and everolimus, do exert both antiangiogenic and immunomodulatory functions. Indeed, these agents affect neutrophil migration, as well as T lymphocyte-DC cross-talk, DC maturation and immune cell metabolism and reactivity. In this review, we overview the essential role of innate and adaptive immune response in RCC proliferation, invasion and metastasis and the relationship between tumor-associated immune cells and the response to targeted agents approved for the treatment of metastatic RCC.

Sunitinib indirectly enhanced anti-tumor cytotoxicity of cytokine-induced killer cells and CD3⁺CD56⁺ subset through the co-culturing dendritic cells

Cytokine-induced killer (CIK) cells have reached clinical trials for leukemia and solid tumors. Their anti-tumor cytotoxicity had earlier been shown to be intensified after the co-culture with dendritic cells (DCs). We observed markedly enhanced anti-tumor cytotoxicity activity of CIK cells after the co-culture with sunitinib-pretreated DCs over that of untreated DCs. This cytotoxicity was reliant upon DC modulation by sunitinib because the direct exposure of CIK cells to sunitinib had no significant effect. Sunitinib promoted Th1-inducing and pro-inflammatory phenotypes (IL-12, IFN-γ and IL-6) in DCs at the expense of Th2 inducing phenotype (IL-13) and regulatory phenotype (PD-L1, IDO). Sunitinib-treated DCs subsequently induced the upregulation of Th1 phenotypic markers (IFN-γ and T-bet) and the downregulation of the Th2 signature (GATA-3) and the Th17 marker (RORC) on the CD3⁺CD56⁺ subset of CIK cells. It concluded that sunitinib-pretreated DCs drove the CD3⁺CD56⁺ subset toward Th1 phenotype with increased anti-tumor cytotoxicity.

Immunological off-target effects of standard treatments in gastrointestinal cancers

The effects on immune cells and the inflammatory microenvironment of commonly applied cancer treatments (chemotherapeutic or biologic agents, interventional radiologic procedures) have become better appreciated. Likewise, the contribution of the immune system toward the effectiveness of these treatments is clearer. The relevance of immune evasion by developing tumors is endorsed by its inclusion as one of the (updated) hallmarks of cancer. A greater understanding of this dimension can potentially lead to novel applications of existing standard of care therapies, in addition to potentiating their effect. This review summarizes the immune aspects of currently employed therapies-cytotoxic chemotherapeutics, biologic agents and interventional radiologic procedures-in solid tumor malignancies with a particular focus on those agents used in gastrointestinal cancers.

Sorafenib relieves cell-intrinsic and cell-extrinsic inhibitions of effector T cells in tumor microenvironment to augment antitumor immunity

Sorafenib, a multitargeted antiangiogenic tyrosine kinase inhibitor, is the standard of care for patients with advanced hepatocellular carcinoma (HCC). Cumulating evidence suggests that sorafenib differentially affects immune cells; however, whether this immunomodulatory effect has any impact on antitumor immune responses is unknown. Using an orthotopic mouse model of HCC and tumor-free mice, we investigated the effects of sorafenib on antitumor immunity and characterized the underlying mechanisms. Sorafenib treatment inhibited tumor growth and augmented antitumor immune responses in mice bearing established orthotopic HCC. The tumor-specific effector T cell functions were upregulated, while the proportion of PD-1-expressing CD8(+) T cells and regulatory T cells (Tregs) was reduced in tumor microenvironment of sorafenib-treated mice. Mechanistically, the sorafenib-mediated effects on Tregs could be independent of its direct tumor-suppressing activities. Sorafenib treatment reduced Treg numbers by inhibiting their proliferation and inducing apoptosis. Moreover, sorafenib inhibited the function of Tregs, characterized by diminished expression of Treg-associated molecules important for their function and by their impaired suppressive capacity. These data reveal that sorafenib treatment enhanced functions of tumor-specific effector T cells as well as relieved PD-1-mediated intrinsic and Treg-mediated non-cell-autonomous inhibitions in tumor microenvironment leading to effective antitumor immune responses. In addition to the well-known tumor-inhibiting activity of sorafenib, its enhancement of antitumor immunity may also contribute to the clinical efficacy. Our findings uncover a previously unrecognized mechanism of action of sorafenib and indicate that sorafenib represents a potential targeted agent suitable to be combined with immunotherapeutic approaches to treat cancer patients.