Sunitinib reverses type-1 immune suppression and decreases T-regulatory cells in renal cell carcinoma patients

Adoptive T-Cell Therapy for Solid Tumors

Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of immunotherapy wherein autologous T cells are genetically modified to express chimeric receptors encoding an antigen-specific single-chain variable fragment and various costimulatory molecules. Upon administration, these modified T cells traffic to, and recognize, cancer cells in an HLA-independent manner. CAR T-cell therapy has shown remarkable success in the treatment of CD-19-expressing B-cell acute lymphocytic leukemia. However, clinical gains to the same magnitude have not been reported in solid tumors. Several known obstacles to CAR T-cell therapy for solid tumors include target antigen identification, effective trafficking to the tumor, robust activation, proliferation, and in vivo cytotoxicity. Beyond these T-cell intrinsic properties, a complex and dynamic immunosuppressive tumor microenvironment in solid tumors hinders T-cell efficacy. Notable advancements in CAR design to include multiple costimulatory molecules, ligands, and soluble cytokines have shown promise in preclinical models, and some of these are currently in early-phase clinical trials. In this review, we discuss selected solid tumor malignancies and relevant preclinical data and highlight clinical trial results that are available. Furthermore, we outline some obstacles to CAR T-cell therapy for each tumor and propose strategies to overcome some of these limitations.

Adoptive T-Cell Therapy for Solid Tumors

Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of immunotherapy wherein autologous T cells are genetically modified to express chimeric receptors encoding an antigen-specific single-chain variable fragment and various costimulatory molecules. Upon administration, these modified T cells traffic to, and recognize, cancer cells in an HLA-independent manner. CAR T-cell therapy has shown remarkable success in the treatment of CD-19-expressing B-cell acute lymphocytic leukemia. However, clinical gains to the same magnitude have not been reported in solid tumors. Several known obstacles to CAR T-cell therapy for solid tumors include target antigen identification, effective trafficking to the tumor, robust activation, proliferation, and in vivo cytotoxicity. Beyond these T-cell intrinsic properties, a complex and dynamic immunosuppressive tumor microenvironment in solid tumors hinders T-cell efficacy. Notable advancements in CAR design to include multiple costimulatory molecules, ligands, and soluble cytokines have shown promise in preclinical models, and some of these are currently in early-phase clinical trials. In this review, we discuss selected solid tumor malignancies and relevant preclinical data and highlight clinical trial results that are available. Furthermore, we outline some obstacles to CAR T-cell therapy for each tumor and propose strategies to overcome some of these limitations.

The relative change in regulatory T cells / T helper lymphocytes ratio as parameter for prediction of therapy efficacy in metastatic colorectal cancer patients

Purpose

The evaluation of regulatory T (Treg) (CD4⁺CD25^high CD127^neg) lymphocyte count with respect to the T helper (TH) (CD4) number has been shown to represent the main immune parameters capable of signifying the functional status of the anticancer immunity in cancer patients. This study is aimed to explore a correlation between therapy efficacy and changes in Treg/TH ratio and other biochemical and haematological parameters in patients with metastatic colorectal cancer (mCRC).

Experimental Design

Measurements of regulatory T cells were performed by flow cytometric analysis pre- and post-therapies in a prospective study.

Results

We investigated levels of Treg/TH ratio in the peripheral blood of 25 mCRC patients pre- and post-chemotherapy ± targeted therapy. There were significant differences in levels of Treg/TH ratio pre- and post-treatments among patients on study, patients with partial response (PR), stable disease (SD) and progressive disease (PD) (P= 0.012, P= 0.011, and P= 0.043, respectively). Moreover, the relative change in Treg/TH ratio showed statistically significant difference among patients with PD as compared to those with PR and SD. Our findings demonstrated a statistically significant strong correlation between the relative change in Treg/TH ratio and therapeutic response. (Spearman's rho= 0.788/p<0.001).

Conclusions

The monitoring of the relative change in Treg/TH ratio could constitute a promising clinical index for response prediction and a timely change in regimen. Further prospective evaluations of these parameters investigated, particularly their association with overall survival, are warranted.

Modern Systemic Therapy for Metastatic Renal Cell Carcinoma of the Clear Cell Type

In the last 30 years, there have been many advances in the treatment of metastatic renal cell carcinoma of the clear cell type. Renal cell carcinoma has long been understood to have a component of immune mediation and has been responsive to immune-based therapies; in addition to early cytokine therapy, newer checkpoint inhibition therapies have also demonstrated activity. Molecular characterization of the genome of clear cell renal cell carcinoma enabled identification of the roles of angiogenesis and hypoxic stress. This led to development of small-molecule tyrosine kinase inhibitors and inhibitors of mammalian target of rapamycin that have provided additional benefit to patients. Ongoing strategies of combinations of immune and antiangiogenic therapies may lead to further advancements.

Synergies of Targeting Tumor Angiogenesis and Immune Checkpoints in Non-Small Cell Lung Cancer and Renal Cell Cancer: From Basic Concepts to Clinical Reality

In recent years, considerable advances concerning therapeutic strategies in patients with metastatic cancer have been achieved. Particularly in renal cell cancer (RCC) and advanced stage non-small cell lung cancer (NSCLC), immune-activating and antiangiogenic (AA) drugs (i.e., checkpoint antibodies and vascular endothelial growth factor (VEGF)/VEGF receptors (VEGFR) targeting compounds, respectively) have been successfully developed. As immune-effector cells have to enter the tumor, it is tempting to speculate that the combination of immunotherapy with AA treatment may induce synergistic effects. In this short review, we explore the theoretical background and the therapeutic potential of this novel treatment option for patients with advanced RCC or NSCLC. We discuss the growing body of evidence that pro-angiogenic factors negatively modulate the T-cell-mediated immune response and examine the preclinical evidence for testing combined immune-activating and AA therapy concepts in clinical practice. Particular attention will also be paid to potential novel treatment-related adverse events induced by combination treatment.

Chimeric antigen receptor-T cell therapy for solid tumors require new clinical regimens

INTRODUCTION

Chimeric antigen receptor modified T cell (CAR-T) therapy has achieved encouraging breakthroughs in the treatment of hematological malignancies. Nevertheless, this success has not yet been extrapolated to solid tumors. This review focuses on new clinical regimens that could improve the therapeutic efficacy of CAR-T in solid tumors. Areas covered: Herein, the authors reviewed recent clinical trials using CAR-T therapies for the treatment of solid tumors. Specifically, this review covered the following areas: (1) the current status of CAR-T cells in the treatment of solid tumors; (2) the major factors constraining the efficacy of CAR-T cells in solid tumors; and (3) opinions regarding the future of CAR-T as a treatment for solid tumors. Expert commentary: While some recent studies have shown promising results, the ultimate success of CAR-T therapies in solid tumor patients will require the following improvements to clinical regimens: (1) local delivery of CAR-T cells; (2) combination of CAR-T cells with chemotherapeutic drugs to treat metastatic tumors; (3) combination of CAR-T with immune checkpoint inhibitors; (4) combination therapy using CAR-T cells targeting two different antigens; and (5) the use of CAR-T as a strategy to prevent tumor recurrence and metastasis after radical resection.

Sunitinib represses regulatory T cells to overcome immunotolerance in a murine model of hepatocellular cancer

Successful development of immunotherapeutic strategies for hepatocellular cancer (HCC) has been impeded by limited understanding of tumor-induced profound tolerance and lack of a clinically faithful HCC model. Recently, we developed a novel model that recapitulates typical features of human HCC. Using this clinically relevant model, we demonstrate that tumor growth impairs host immunity and causes a profound exhaustion of tumor antigen-specific (TAS) CD8⁺ T cells. Increase in frequency and suppressive function of regulatory T cells (Tregs) is critically involved in this tumor-induced immune dysfunction. We further demonstrate that sunitinib suppresses Tregs and prevents tumor-induced immune tolerance, allowing TAS immunization to activate endogenous CD8⁺ T cells. As a result, this combinational strategy delays tumor growth. Importantly, the additional integration of exogenous naïve TAS CD8⁺ T cells by adoptive cell transfer (ACT) leads to the elimination of the established tumors without recurrence and promotes long-term survival of the treated mice. Mechanistically, sunitinib treatment primes the antitumor immune response by significantly decreasing Treg frequency, reducing TGF-β and IL-10 production by Tregs, and also protecting TAS CD8⁺ T cells from tumor-induced deletion in the setting of HCC. Taken together, sunitinib quantitatively and qualitatively modifies Tregs to overcome tumor-induced immune deficiency, suggesting the potential of sunitinib as a therapeutic immune activator for HCC control.

Nanomaterials for cancer immunotherapy

Cancer immunotherapy is quickly growing to be the fourth most important cancer therapy, after surgery, radiation therapy, and chemotherapy. Immunotherapy is the most promising cancer management strategy because it orchestrates the body's own immune system to target and eradicate cancer cells, which may result in durable antitumor responses and reduce metastasis and recurrence more than traditional treatments. Nanomaterials hold great promise in further improving the efficiency of cancer immunotherapy - in many cases, they are even necessary for effective delivery. In this review, we briefly summarize the basic principles of cancer immunotherapy and explain why and where to apply nanomaterials in cancer immunotherapy, with special emphasis on cancer vaccines and tumor microenvironment modulation.

Emerging immunotherapy in advanced renal cell carcinoma

Immunotherapy has recently catapulted to the forefront of treatments for patients with solid tumors. Given its inherent immunogenic properties, renal cell carcinoma (RCC) has historically responded to immunotherapy and remains primed for further development. Although immunotherapy with high-dose interleukin 2 was a primary treatment for advanced RCC (aRCC), recent discoveries of key molecular and immunological alterations have led to the FDA-approval of nivolumab, an antiprogrammed cell death inhibitor, which has demonstrated an overall survival in patients with previously treated aRCC. However, despite recent therapeutic advances, aRCC remains an incurable disease for most patients. In this review, we assess the current landscape and future developments of immunotherapy in aRCC.

The role and significance of VEGFR2+ regulatory T cells in tumor immunity

Tumor development is closely related to angiogenesis, and VEGFR2 plays an important role in tumor angiogenesis. It is broadly expressed in the blood vessels, especially in the microvessels of tumor tissues. Furthermore, VEGFR2 is detected on the surface of the cell membrane in various immune cells, such as dendritic cells, macrophages, and regulatory T cells (Tregs). Tregs, which are one of the key negative regulatory factors in tumor immune microenvironments, show high-level expression of VEGFR2 which participates in the regulation of immunosuppressive function. VEGFR2+ Tregs play a potent suppressive role in the formation of immunosuppressive microenvironments. A large number of reports have proven the synergistic effects between targeted therapy for VEGFR2 and immunotherapy. The depression of VEGFR2 activity on T cells can significantly reduce the infiltration of Tregs into the tumor tissue. Targeted therapy for VEGFR2+ Tregs also provides a new choice for the clinical treatment of malignant solid tumors. In this paper, the role and significance of VEGFR2+ Tregs in tumor immunity in recent years are reviewed.

Cancer vaccines: Enhanced immunogenic modulation through therapeutic combinations

Therapeutic cancer vaccines have gained significant popularity in recent years as new approaches for specific oncologic indications emerge. Three therapeutic cancer vaccines are FDA approved and one is currently approved by the EMA as monotherapy with modest treatment effects. Combining therapeutic cancer vaccines with other treatment modalities like radiotherapy (RT), hormone therapy, immunotherapy, and/or chemotherapy have been investigated as a means to enhance immune response and treatment efficacy. There is growing preclinical and clinical data that combination of checkpoint inhibitors and vaccines can induce immunogenic intensification with favorable outcomes. Additionally, novel methods for identifying targetable neoantigens hold promise for personalized vaccine development. In this article, we review the rationale for various therapeutic combinations, clinical trial experiences, and future directions. We also highlight the most promising developments that could lead to approval of novel therapeutic cancer vaccines.

Novel immunotherapy in metastatic renal cell carcinoma

Despite the rapid development of therapeutic modalities for metastatic renal cell carcinoma (mRCC) over the past decade to include a number of targeted antiangiogenic therapies and traditional immunotherapy, such as high-dose interleukin-2 and interferon-α, mRCC continues to be associated with poor prognosis. Currently, several novel immunotherapy agents, such as cancer vaccines, adoptive cell therapy, and checkpoint inhibitors, such as programmed cell death-1 (PD-1 present on T cells), one of its ligands (PD-L1 present on antigen-presenting cells and tumor cells), and cytotoxic T-lymphocyte-associated protein-4 pathways, are being studied in mRCC and are showing promise as important steps in the management of this disease. This review summarizes the current landscape of standard and emerging immune therapeutics and other modalities for mRCC.

Sunitinib in the treatment of renal cell carcinoma: an update on recent evidence

Sunitinib is a multitarget tyrosine kinase inhibitor endowed mainly by antiangiogenic effects, although an indirect inhibitory effect on tumor growth and, more recently, a complex activity on antitumor immune response has been described. From approval by the US Food and Drug Administration (FDA) in January 2006, sunitinib represents a key molecule in the treatment of metastatic renal cell carcinoma (mRCC) due to the peculiar molecular pathogenesis of this neoplasm. Over the past 10 years, clinical trials and real-world experiences helped clinicians to understand how, when and for how long to use sunitinib. Although a huge amount of data evidenced the relationship existing between sunitinib dose intensity and improved clinical outcome, the management of sunitinib-induced adverse events is often complex; thus, alternative schedules have been proposed over time which allow increased tolerability, without decreased daily sunitinib exposure, leading to improved clinical outcomes. To date, combinations of sunitinib with other approved targeted agents did not demonstrate any significant benefit over its single-agent use, mainly due to tolerability issues. Sunitinib has also been tested in the adjuvant setting, within the ASSURE and S-TRAC trials, with opposite results; indeed, equivocal risk-stratification criteria, as well as immature overall survival (OS) data prevent any definitive conclusion on this important issue. Despite being on the market for a long time, sunitinib still plays a role as the 'comparator arm' of a number of trials in the field of mRCC. Combinations with immune checkpoint inhibitors and vaccines look promising; once again, sunitinib can help us to optimize mRCC management.

Current Immunotherapeutic Strategies to Enhance Oncolytic Virotherapy

Oncolytic viruses (OV) represent a promising strategy to augment the spectrum of cancer therapeutics. For efficacy, they rely on two general mechanisms: tumor-specific infection/cell-killing, followed by subsequent activation of the host’s adaptive immune response. Numerous OV genera have been utilized in clinical trials, ultimately culminating in the 2015 Food and Drug Administration approval of a genetically engineered herpes virus, Talminogene laherparepvec (T-VEC). It is generally accepted that OV as monotherapy have only modest clinical efficacy. However, due to their ability to elicit specific antitumor immune responses, they are prime candidates to be paired with other immune-modulating strategies in order to optimize therapeutic efficacy. Synergistic strategies to enhance the efficacy of OV include augmenting the host antitumor response through the insertion of therapeutic transgenes such as GM-CSF, utilization of the prime-boost strategy, and combining OV with immune-modulatory drugs such as cyclophosphamide, sunitinib, and immune checkpoint inhibitors. This review provides an overview of these immune-based strategies to improve the clinical efficacy of oncolytic virotherapy.

Myeloid-derived suppressor cells-a new therapeutic target to overcome resistance to cancer immunotherapy

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that accumulate during pathologic conditions, such as cancer. Patients diagnosed with advanced metastatic cancers have an average survival of 12-24 mo, a survival time that hasn't changed significantly in the past 30 yr. Despite some encouraging improvements in response rates and overall survival in patients receiving immunotherapies, such as immune checkpoint inhibitors, most patients will ultimately progress. MDSCs contribute to immunotherapeutic resistance by actively inhibiting antitumor T cell proliferation and cytotoxic activity as well as by promoting expansion of protumorigenic T regulatory cells, thereby, dampening the host immune responses against the tumor. In addition, MDSCs promote angiogenesis, tumor invasion, and metastasis. Thus, MDSCs are potential therapeutic targets in cases of multiple cancers. This review focuses on the phenotypic and functional characteristics of MDSCs and provides an overview of the mono- and combinatorial-therapeutic strategies that target MDSCs with an objective of enhancing the efficacy of cancer immunotherapies.

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.

Therapeutic efficacy of combined vaccination against tumor pericyte-associated antigens DLK1 and DLK2 in mice

When compared with vascular cells in normal tissues, pericytes and vascular endothelial cells (VEC) in tumor blood vessels exhibit altered morphology and epigenetic programming that leads to the expression of unique antigens that allow for differential recognition by CD8⁺ T cells. We have previously shown that the Notch antagonist delta-like homolog 1 (DLK1) is a tumor pericyte-associated antigen expressed in setting of melanoma and a range of carcinomas. In this report, we show that therapeutic vaccination against DLK1 in murine models results in slowed tumor growth, but also to the compensatory expression of the DLK1 homolog, DLK2, by tumor-associated pericytes. Vaccines targeting both DLK1 and DLK2 resulted in superior antitumor benefits in association with improved activation and recruitment of antigen-specific Type 1 CD8⁺ T cells, reduced presence of myeloid-derived suppressive cells, T regulatory cell and tumor vascular normalization. The antitumor efficacy of vaccines coordinately targeting DLK1 and DLK2 was further improved by inclusion of PD-L1 blockade, thus defining a combination immunotherapy theoretically suitable for the treatment of a broad range of solid (vascularized) cancers.

[Immunotherapy in uropathology]

The algorithms for treatment of metastatic cancers are evolving due to positive results obtained with immunotherapy. Therapeutics approaches to stimulate the immune system have already been used in the treatment of kidney and bladder cancer, such as the administration of cytokines and BCG therapy, confirming the immunogenicity of these tumors. The aim of immunotherapies is not only to activate the immune system against tumor cells, but also to take into account the tumor-induced suppressive microenvironment, in particular by removing the anergy of T-cell lymphocytes, and by targeting the co-stimulation inhibitors molecules. Among the genito-urinary cancers, second-line clinical trials have clearly shown that kidney and bladder cancers are sensitive to the inhibition of PD-1/PD-L1 axis and have already achieved FDA approvals for some molecules. Numerous other clinical trials are underway, particularly in first-line treatment in bladder and renal cancers. Refractory testicular cancer could also benefit from these treatments. Other approaches using vaccine therapy especially in castration-resistant prostate cancer are also of interest. We will see, in this chapter dedicated to the urogenital cancers, the benefit of the immunotherapy by resituating it in the genetic and immunological context of each organ. We will also present briefly the therapeutic outlines and the place of biomarkers.

Historical Evolution of Second-Line Therapy in Non-Small Cell Lung Cancer

Innovative therapeutic agents have significantly improved outcome with an acceptable safety profile in a substantial proportion of non-small cell lung cancer (NSCLC) patients, who depend on oncogenic molecular alterations for their malignant phenotype. Despite the survival improvement achieved with first-line chemotherapy, about 30% of patients do not obtain a tumor response. Moreover, those patients, initially sensitive to treatment, acquire resistance and develop tumor progression after a median of about 5 months. Approximately 60% of the patients progressing from first-line chemotherapy receive further systemic treatment in the second-line setting. Moreover, new options have emerged in the second-line armamentarium for the treatment of patients with NSCLC, including immune checkpoint inhibitors and antiangiogenic agents. The current review provides an overview on the clinical studies that gained the approval of chemotherapy agents (docetaxel and pemetrexed) and epidermal growth factor receptor gene–tyrosine kinase inhibitors as second-line treatment options for NSCLC patients, not carrying molecular alterations.

Tumor-targeted delivery of sunitinib base enhances vaccine therapy for advanced melanoma by remodeling the tumor microenvironment

Development of an effective treatment against advanced tumors remains a major challenge for cancer immunotherapy. We have previously developed a potent mannose-modified lipid calcium phosphate (LCP) nanoparticle (NP)-based Trp2 vaccine for melanoma therapy, but because this vaccine can induce a potent anti-tumor immune response only during the early stages of melanoma, poor tumor growth inhibition has been observed in more advanced melanoma models, likely due to the development of an immune-suppressive tumor microenvironment (TME). To effectively treat this aggressive tumor, a multi-target receptor tyrosine kinase inhibitor, sunitinib base, was efficiently encapsulated into a targeted polymeric micelle nano-delivery system (SUNb-PM), working in a synergistic manner with vaccine therapy in an advanced mouse melanoma model. SUNb-PM not only increased cytotoxic T-cell infiltration and decreased the number and percentage of MDSCs and Tregs in the TME, but also induced a shift in cytokine expression from Th2 to Th1 type while remodeling the tumor-associated fibroblasts, collagen, and blood vessels in the tumor. Additionally, inhibition of the Stat3 and AKT signaling pathways by SUNb-PM may induce tumor cell apoptosis or decrease tumor immune evasion. Our findings indicated that targeted delivery of a tyrosine kinase inhibitor to tumors can be used in a novel synergistic way to enhance the therapeutic efficacy of existing immune-based therapies for advanced melanoma.

Immuno-oncology for renal cell carcinoma treatment: future perspectives for combinations and sequences with molecularly targeted agents

INTRODUCTION

From a theoretical viewpoint, combining molecularly targeted agents endowed with antiangiogenic properties with immunotherapy makes sense in treatment of metastatic renal cell carcinoma (RCC); this neoplasm is highly angiogenesis-dependent, as well as potentially immunogenic. Areas covered: The authors performed a literature search looking for clinical trials aimed at evaluating efficacy and tolerability of combinations (or sequences) of molecularly targeted agents and different immunotherapeutic approaches in metastatic RCC. Expert opinion: Combinations of molecularly targeted agents with old immunotherapeutics (i.e., cytokines) seem to add little to the presently available treatment standards (mainly monotherapy with targeted agents). Newer combinations with immune checkpoint inhibitors are promising but cumulative toxicity is an important issue, although highly dependent on the different companion drugs. Combinations with vaccines are ongoing, but first available data are not encouraging. A more thorough comprehension of the complex effects of these combinations on the immune system is mandatory to develop less empiric treatments.

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.

Immunomodulatory and Antitumor Effects of a Novel TLR7 Agonist Combined with Lapatinib

As new treatment approaches, both immunotherapy and targeted treatments have been used in the clinical treatment of cancers. These therapies are different from traditional surgery, chemotherapy and radiotherapy. Use of a combination of immunotherapy and targeted treatments may improve tumor clearance. We investigated the feasibility of combining tyrosine kinase inhibitors (TKIs, targeted drugs) and SZU-101 (a novel TLR7 agonist synthesized by our laboratory). Thirteen different TKIs were combined with or without SZU-101 and studied to determine their effects on immunocytes. On the basis of the distinctive results, lapatinib and sunitinib were selected for further tumor-inhibition investigation and determination of the underlying mechanism. Interestingly, we found lapatinib to work better with SZU-101, enhancing tumor clearance in vivo, without affecting the TLR7-NF-κB pathway activated by the TLR7 agonist in mouse spleen lymphocytes and bone marrow dendritic cells (BMDCs).

Sunitinib in the treatment of metastatic renal cell carcinoma

Sunitinib is an oral multi-targeted tyrosine kinase inhibitor (TKI) that targets various receptors, including vascular endothelial growth factor receptors (VEGFRs). Sunitinib received approval in 2006 and became a standard treatment option in the first-line treatment of metastatic renal cell cancer (mRCC) after a phase III trial showed superiority compared with interferon alpha (IFN-α). Sunitinib has also shown activity in second-line treatment in several trials. Most of the combination trials with sunitinib with various agents have led to considerable toxicity without improving efficacy. Sunitinib alone causes significant side effects and has a distinct profile with diarrhoea, hypertension, skin effects hypothyroidism, fatigue and nausea of special interest. The recommended dose of sunitinib in mRCC is 50 mg orally daily for 4 weeks, followed by 2 weeks off treatment (4/2 schedule). An alternative 2 weeks on, 1 week off schedule (2/1 schedule) seems to be of similar efficacy and better tolerability and could be more widely used in the future. An intermittent treatment strategy with a stop in remission and re-induction after progression showed efficacy in smaller trials and is currently being evaluated in a phase III trial. Direct comparison of sunitinib with pazopanib in first-line treatment showed a similar efficacy for both TKIs with a distinct toxicity profile. Data from two phase II trials showed that sunitinib has also activity in non-clear cell cancer and is an option due to a lack of better alternatives. Currently, after immune checkpoint inhibitors have shown very promising results in the second-line treatment of RCC, they are being tested in a number of phase III trials in the first-line setting. The future will show the position of sunitinib in the first-line treatment of RCC in the era of the immune checkpoint inhibitors.

The importance of correctly timing cancer immunotherapy

INTRODUCTION

The treatment options for cancer-surgery, radiotherapy and chemotherapy-are now supplemented with immunotherapy. Previously underappreciated but now gaining strong interest are the immune modulatory properties of the three conventional modalities. Moreover, there is a better understanding of the needs and potential of the different immune therapeutic platforms. Key to improved treatment will be the combinations of modalities that complete each other's shortcomings. Area covered: Tumor-specific T-cells are required for optimal immunotherapy. In this review, the authors focus on the correct timing of different types of chemotherapeutic agents or immune modulators and immunotherapeutic drugs, not only for the activation and expansion of tumor-specific T-cells but also to support and enhance their anti-tumor efficacy. Expert opinion: At an early phase of disease, clinical success can be obtained using single treatment modalities but at later disease stages, combinations of several modalities are required. The gain in success is determined by a thorough understanding of the direct and indirect immune effects of the modalities used. Profound knowledge of these effects requires optimal tuning of immunomonitoring. This will guide the appropriate combination of treatments and allow for correct sequencing the order and interval of the different therapeutic modalities.

Leukocyte trafficking is not affected by multikinase inhibitors sunitinib or sorafenib in mice

Sunitinib and sorafenib are broad-spectrum tyrosine kinase inhibitors (TKI) targeting, for example, VEGF1-3, PDGFRb, RET, FLT3, CD117 (c-KIT) and CSF-1R cell membrane receptors thus suppressing tumor angiogenesis and cancer cell growth. Recently it has been suggested that the kinases targeted by Sunitinib and/or Sorafenib regulate leukocyte transmigration, which might in part be responsible for the often-observed reduction in tumor-associated myeloid derived suppressor cells and regulatory T cells. The aim of the current study is to determine whether sunitinib or sorafenib inhibit leukocyte extravasation. Sunitinib, sorafenib, or vehicle treated animals did not show any difference in leukocyte trafficking either in peritonitis or in vivo homing experiments, although sunitinib treatment effectively inhibited growth of B16 melanoma tumors in WT, SCID and SCID beige mice. Inhibition of tumor growth was associated with an increased number of infiltrating CD11b+ cells in the tumor, while the numbers of CD8, Gr-1 and F4/80 expressing cells were unchanged. In conclusion, the findings suggest that despite multiple targets with a potential role in leukocyte extravasation, neither sunitinib nor sorafenib effectively inhibits this process in vivo. Thus, the observed specific effect on CD11b cells among tumor infiltrating leukocytes is most likely an indirect effect.

The Potential of Combined Immunotherapy and Antiangiogenesis for the Synergistic Treatment of Advanced NSCLC

Over the past few years, there have been considerable advances in the treatments available to patients with metastatic or locally advanced NSCLC, particularly those who have progressed during first-line treatment. Some of the treatment options available to patients are discussed here, with a focus on checkpoint inhibitor immunotherapies (nivolumab and pembrolizumab) and antiangiogenic agents (bevacizumab, ramucirumab, and nintedanib). It is hypothesized that combining immunotherapy with antiangiogenic treatment may have a synergistic effect and enhance the efficacy of both treatments. In this review, we explore the theory and potential of this novel treatment option for patients with advanced NSCLC. We discuss the growing body of evidence that proangiogenic factors can modulate the immune response (both by reducing T-cell infiltration into the tumor microenvironment and through systemic effects on immune-regulatory cell function), and we examine the preclinical evidence for combining these treatments. Potential challenges are also considered, and we review the preliminary evidence of clinical efficacy and safety with this novel combination in a variety of solid tumor types.

Medical treatment of renal cancer: new horizons

Renal cell carcinoma (RCC) makes up 2-3% of adult cancers. The introduction of tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin inhibitors in the mid-2000s radically changed the management of RCC. These targeted treatments superseded immunotherapy with interleukin-2 and interferon. The pendulum now appears to be shifting back towards immunotherapy, with the evidence of prolonged overall survival of patients with metastatic RCC on treatment with the anti-programmed cell death 1 ligand monoclonal antibody, nivolumab. Clinical prognostic criteria aid prediction of relapse risk for resected localised disease. Unfortunately, for patients at high risk of relapse, no adjuvant treatment has yet shown benefit, although further trials are yet to report. Clinical prognostic models also have a role in the management of advanced disease; now there is a pressing need for predictive biomarkers to direct therapy. Treatment selection for metastatic disease is currently based on histology, prognostic group and patient preference based on side effect profile. In this article, we review the current medical and surgical management of localised, oligometastatic and advanced RCC, including side effect management and the evidence base for management of poor-risk and non-clear cell disease. We discuss recent results from clinical trials and how these are likely to shape future practice and a renaissance of immunotherapy for renal cell cancer.

Active surveillance in metastatic renal-cell carcinoma: a prospective, phase 2 trial

BACKGROUND

A subset of patients with metastatic renal-cell carcinoma show indolent growth of metastases. Because of the toxicity and non-curative nature of systemic therapy, some of these patients could benefit from initial active surveillance. We aimed to characterise the time to initiation of systemic therapy in patients with metastatic renal-cell carcinoma under active surveillance.

METHODS

In this prospective phase 2 trial, we enrolled patients with treatment-naive, asymptomatic, metastatic renal-cell carcinoma from five hospitals in the USA, Spain, and the UK. Patients were radiographically assessed at baseline, every 3 months for year 1, every 4 months for year 2, then every 6 months thereafter. Patients continued on observation until initiation of systemic therapy for metastatic renal-cell carcinoma; a decision that was made at the discretion of the treating physician and patient. The primary endpoint of the study was time to initiation of systemic therapy in the per-protocol population. The follow-up of patients is ongoing.

FINDINGS

Between Aug 21, 2008, and June 7, 2013, we enrolled 52 patients. Median follow-up of patients in the study was 38·1 months (IQR 29·4-48·9). In the 48 patients included in analysis, median time on surveillance from registration on study until initiation of systemic therapy was 14·9 months (95% CI 10·6-25·0). Multivariate analysis showed that higher numbers of International Metastatic Database Consortium (IMDC) adverse risk factors (p=0·0403) and higher numbers of metastatic disease sites (p=0·0414) were associated with a shorter surveillance period. 22 (46%) patients died during the study period, all from metastatic renal-cell carcinoma.

INTERPRETATION

A subset of patients with metastatic renal-cell carcinoma can safely undergo surveillance before starting systemic therapy. Additional investigation is required to further define the benefits and risks of this approach.

FUNDING

None.

Pharmacokinetics, pharmacodynamics and clinical efficacy of nivolumab in the treatment of metastatic renal cell carcinoma

INTRODUCTION

Nivolumab is a recombinant, humanized monoclonal antibody that binds PD-1. The binding of PD-1 with PD-L1, expressed on antigen-presenting cells and tumor cells, suppresses the ability of T-lymphocytes to recognize and destroy tumor cells. Nivolumab reverts this inhibitory signal and has led to a significant prolongation of overall survival in patients with metastatic renal cell carcinoma (RCC).

AREAS COVERED

The rationale for immunotherapy in metastatic RCC, key immune checkpoint pathways, nivolumab pharmacodynamics, results from the main clinical trials, and predictors of response are discussed.

EXPERT OPINION

Nivolumab demonstrated a statistically significant advantage over everolimus in overall survival in metastatic RCC patients after first-line antiangiogenic therapy. Nevertheless, a number of issues remain to be resolved regarding the use of this drug in RCC. It is now imperative to identify which patients can benefit most from immunotherapy and studies are ongoing to define its role in other settings and/or in combinations with antiCTLA4 or antiangiogenic drugs.

Antitumour and antiangiogenic activities of [Pt(O,O'-acac)(γ-acac)(DMS)] in a xenograft model of human renal cell carcinoma

BACKGROUND AND PURPOSE

It is thought that the mechanism of action of anticancer chemotherapeutic agents is mainly due to a direct inhibition of tumour cell proliferation. In tumour specimens, the endothelial cell proliferation rate increases, suggesting that the therapeutic effects of anticancer agents could also be attributed to inhibition of tumour angiogenesis. Hence, we investigated the potential effects of [Pt(O,O'-acac)(γ-acac)(DMS)] ([Pt(DMS)]), a new platinum drug for non-genomic targets, on human renal carcinoma and compared them with those of the well-established anticancer drug, cisplatin.

EXPERIMENTAL APPROACH

Tumour growth, tumour cell proliferation and microvessel density were investigated in a xenograft model of renal cell carcinoma, developed by injecting Caki-1 cells into BALB/c nude mice. The antiangiogenic potential of compounds was also investigated using HUVECs.

KEY RESULTS

Treatment of the Caki-1 cells with cisplatin or [Pt(DMS)] resulted in a dose-dependent inhibition of cell survival, but the cytotoxicity of [Pt(DMS)] was approximately fivefold greater than that of cisplatin. [Pt(DMS)] was much more effective than cisplatin at inhibiting tumour growth, proliferation and angiogenesis in vivo, as well as migration, tube formation and MMP1, MMP2 and MMP9 secretion of endothelial cells in vitro. Whereas, cisplatin exerted a greater cytotoxic effect on HUVECs, but did not affect tube formation or the migration of endothelial cells. In addition, treatment of the xenograft mice with [Pt(DMS)] decreased VEGF, MMP1 and MMP2 expressions in tumours.

CONCLUSIONS AND IMPLICATIONS

The antiangiogenic and antitumour activities of [Pt(DMS)] provide a solid starting point for its validation as a suitable candidate for further pharmacological testing.

PD-1+ and Foxp3+ T cell reduction correlates with survival of HCC patients after sorafenib therapy

BACKGROUND

Sorafenib is an oral antiangiogenic agent administered in advanced-stage hepatocellular carcinoma (HCC). Based on preclinical and human studies, we hypothesized that, in addition to its antiangiogenic properties, sorafenib may beneficially reduce the extent of the immunosuppressive network in HCC patients. To test this hypothesis, we examined whether alterations in the immunosuppressive burden of advanced-stage HCC patients correlated with clinical outcome.

METHODS

In before and after sorafenib treatment, blood samples collected from 19 patients with advanced HCC, the frequency of PD-1⁺ T cells, Tregs, and myeloid derived suppressor cells (MDSC) were quantified by multiparameter FACS. Cytokine levels in plasma were determined by ELISA.

RESULTS

Overall survival (OS) was significantly impacted by the reduction in the absolute number of both CD4⁺PD-1⁺ T cells and CD8⁺PD-1⁺ T cells following sorafenib treatment. Significant decreases in the frequency and absolute number of Foxp3⁺ Tregs were also observed, and a statistically significant improvement in OS was noted in patients exhibiting a greater decrease in the number of Foxp3⁺ Tregs. The ratio of CD4⁺CD127⁺PD-1^- T effector cells to CD4⁺Foxp3⁺PD-1⁺ Tregs was significantly increased following treatment with sorafenib. Increased frequency of CD4⁺CD127⁺ T effector cells in the posttreatment samples significantly correlated with OS.

CONCLUSION

This study is the first to our knowledge to demonstrate the potent immunomodulatory effects of sorafenib therapy on PD-1⁺ T cells and Tregs and the ensuing correlation with survival. These phenotypes could serve as predictive biomarkers to identify HCC patients who are likely to benefit from sorafenib treatment.

TRIAL REGISTRATION

Registration is not required for observational studies.

FUNDING

This study was supported by NCI Core Grant to RPCI (NIH P30 CA016056) and discretionary funds to Y. Thanavala.

Myeloid-derived suppressor cells as effectors of immune suppression in cancer

The tumor microenvironment consists of an immunosuppressive niche created by the complex interactions between cancer cells and surrounding stromal cells. A critical component of this environment are myeloid-derived suppressor cells (MDSCs), a heterogeneous group of immature myeloid cells arrested at different stages of differentiation and expanded in response to a variety of tumor factors. MDSCs exert diverse effects in modulating the interactions between immune effector cells and the malignant cells. An increased presence of MDSCs is associated with tumor progression, poorer outcomes, and decreased effectiveness of immunotherapeutic strategies. In this article, we will review our current understanding of the mechanisms that underlie MDSC expansion and their immune-suppressive function. Finally, we review the preclinical studies and clinical trials that have attempted to target MDSCs, in order to improve responses to cancer therapies.

Signal transducer and activator of transcription 3 in myeloid-derived suppressor cells: an opportunity for cancer therapy

Cancer progression is in part determined by interactions between cancer cells and stromal cells in the tumor microenvironment (TME). The identification of cytotoxic tumor-infiltrating lymphocytes has instigated research into immune stimulating cancer therapies. Although a promising direction, immunosuppressive mechanisms exerted at the TME hamper its success. Myeloid-derived suppressor cells (MDSCs) have come to the forefront as stromal cells that orchestrate the immunosuppressive TME. Consequently, this heterogeneous cell population has been the object of investigation. Studies revealed that the transcription factor signal transducer and activator of transcription 3 (STAT3) largely dictates the recruitment, activation and function of MDSCs in the TME. Therefore, this review will focus on the role of this key transcription factor during the MDSC's life cycle and on the therapeutic opportunities it offers.

Checkpoint inhibitors and other novel immunotherapies for advanced renal cell carcinoma

The management of advanced renal cell carcinoma (RCC) has dramatically changed over the past decade. Therapies that target the vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) pathways have considerably expanded treatment options; however, most patients with advanced RCC still have limited overall survival. Increased understanding of the mechanisms of T cell-antigen recognition and function has led to the development of novel immunotherapies to treat cancer, chief among them inhibitors of checkpoint receptors - molecules whose function is to restrain the host immune response. In 2015, the FDA approved the first checkpoint inhibitor nivolumab for patients with advanced RCC following treatment with antiangiogenic therapy based on improved overall survival compared with the standard of care. Ongoing phase III trials are comparing checkpoint-inhibitor-based combination regimens with antiangiogenesis agents in the first-line setting. The field is evolving rapidly, with many clinical trials already testing several checkpoint inhibitors alone, in combination, or with other targeted therapies. In addition, different novel immune therapies are being investigated including vaccines, T-cell agonists, and chimeric antigen receptor T cells. Determining which patients will benefit from these therapies and which combination approaches will result in better response will be important as this field evolves.

Immunotherapy advances in uro-genital malignancies

Immunotherapy for the treatment of cancer has made significant progresses over the last 20 years. Multiple efforts have been attempted to restore immune-mediated tumor elimination, leading to the development of several targeted immunotherapies. Data from recent clinical trials suggest that these agents might improve the prognosis of patients with advanced genito-urinary (GU) malignancies. Nivolumab has been the first immune checkpoint-inhibitor approved for pre-treated patients with metastatic renal cell carcinoma. Pembrolizumab and atezolizumab have shown promising results in both phase I and II trials in urothelial carcinoma. Brentuximab vedotin has demonstrated early signals of clinical activity and immunomodulatory effects in highly pre-treated patients with testicular germ cell tumors. In this review, we have summarized the major clinical achievements of immunotherapy in GU cancers, focusing on immune checkpoint blockade as well as the new immunomodulatory monoclonal antibodies (mAbs) under clinical evaluation for these malignancies.

Repurposing Sunitinib with Oncolytic Reovirus as a Novel Immunotherapeutic Strategy for Renal Cell Carcinoma

PURPOSE

In addition to their direct cytopathic effects, oncolytic viruses are capable of priming antitumor immune responses. However, strategies to enhance the immunotherapeutic potential of these agents are lacking. Here, we investigated the ability of the multi-tyrosine kinase inhibitor and first-line metastatic renal cell carcinoma (RCC) agent, sunitinib, to augment the antitumor immune response generated by oncolytic reovirus.

EXPERIMENTAL DESIGN

In vitro, oncolysis and chemokine production were assessed in a panel of human and murine RCC cell lines after exposure to reovirus, sunitinib, or their combination. In vivo, the RENCA syngeneic murine model of RCC was employed to determine therapeutic and tumor-specific immune responses after treatment with reovirus (intratumoral), sunitinib, or their combination. Parallel investigations employing the KLN205 syngeneic murine model of lung squamous cell carcinoma (NSCLC) were conducted for further validation.

RESULTS

Reovirus-mediated oncolysis and chemokine production was observed following RCC infection. Reovirus monotherapy reduced tumor burden and was capable of generating a systemic adaptive antitumor immune response evidenced by increased numbers of tumor-specific CD8⁺ IFNγ-producing cells. Coadministration of sunitinib with reovirus further reduced tumor burden resulting in improved survival, decreased accumulation of immune suppressor cells, and the establishment of protective immunity upon tumor rechallenge. Similar results were observed for KLN205 tumor-bearing mice, highlighting the potential broad applicability of this approach.

CONCLUSIONS

The ability to repurpose sunitinib for augmentation of reovirus' immunotherapeutic efficacy positions this novel combination therapy as an attractive strategy ready for clinical testing against a range of histologies, including RCC and NSCLC. Clin Cancer Res; 22(23); 5839-50. ©2016 AACR.

The association of clinical outcome and peripheral T-cell subsets in metastatic colorectal cancer patients receiving first-line FOLFIRI plus bevacizumab therapy

The first-line standard of care for patients with metastatic colorectal cancer (mCRC) is FOLFIRI (irinotecan, levo-leucovorin, 5-fluorouracil (5-FU)) plus bevacizumab. With the renewed interest in cancer immunotherapy with agents such as vaccines, checkpoint inhibitors and immune modulators, the possibility exists for the use of one or more of these immunotherapeutics in the first-line setting and thus in combination with the FOLFIRI and bevacizumab regimen. Studies were undertaken to study the effects of FOLFIRI and bevacizumab therapy on peripheral T-cell subsets, and to determine if there are any associations between these subsets and response to therapy. Peripheral blood mononuclear cell subsets of patients with mCRC (n = 23) were analyzed prior to and during therapy. While there were differences among patients, the majority of patients showed either a minimal change or an increase in CD4(+) T cell to regulatory T cell (Treg) ratios during therapy, as well as either minimal change or a decrease in Treg suppressive activity during therapy. There was also an association (p = 0.036) between a decrease in Treg frequency during FOLFIRI therapy and overall survival, and an association (p = 0.037) between the frequency of Tregs prior to therapy and progression-free survival. Responders to the chemotherapy by RECIST criteria also had a greater decrease in Tregs during therapy vs. pre-therapy (p = 0.0064) as compared to non-responders. While the number of mCRC patients undergoing chemotherapy in this study is relatively small, it provides the rationale for the use of immunotherapeutics in this first-line metastatic setting.

Myeloid-derived suppressor cells: The green light for myeloma immune escape

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous, immature myeloid cell population with the ability to suppress innate and adaptive immune responses that promote tumor growth. MDSCs are increased in patients with multiple myeloma (MM) and have bidirectional interaction with tumors within the MM microenvironment. MM-MDSCs promote MM tumor growth and induce immune suppression; conversely, MM cells induce MDSC development and survival. Although the role of MDSCs in infections, inflammatory diseases and solid tumors has been extensively characterized, their tumor-promoting and immune-suppressive role in MM and the MM microenvironment is only beginning to emerge. The presence and activation of MDSCs in MM patients has been well documented; however, the direct actions and functional consequences of MDSCs on cancer cells is poorly defined. Immunosuppressive MDSCs play an important role in tumor progression primarily because of their capability to promote immune-escape, angiogenesis, drug resistance and metastasis. However, their role in the bone marrow (BM), the primary MM site, is poorly understood. MM remains an incurable malignancy, and it is likely that the BM microenvironment protects MM against chemotherapy agents and the host immune system. A growing body of evidence suggests that host immune cells with a suppressive phenotype contribute to a myeloma immunosuppressive network. Among the known suppressor cells, MDSCs and T regulatory cells (Tregs) have been found to be significantly increased in myeloma patients and their levels correlate with disease stage and clinical outcome. Furthermore, it has been shown that MDSC can mediate suppression of myeloma-specific T-cell responses through the induction of T-cell anergy and Treg development in the MM microenvironment. Here, we review clinical correlations and the preclinical proof-of-principle data on the role of MDSCs in myeloma immunotolerance and highlight the mechanistically relevant MDSC-targeted compounds and their potential utility in a new approach for anti-myeloma therapy.

Therapeutic vaccines for prostate cancer: recent advances and future directions

In recent years, therapeutic cancer vaccines have emerged as a viable and promising treatment for prostate cancer. Beyond sipuleucel-T, phase III trials are evaluating multiple vaccine platforms in men with this disease. Growing data evaluating vaccine therapies suggests that these agents are more effective in patients with more indolent and possibly also earlier stages of disease. In addition, a wealth of preclinical data has shown that traditional prostate cancer treatments including anti androgens, cytotoxic and radiation therapies may provide immunologic synergy when given in combination with vaccine platforms. Building off this data, numerous clinical trials are evaluating therapeutic cancer vaccines in early stage prostate cancer and also in combination with traditional prostate cancer therapies. In addition, in order to optimize immune responses, ongoing trials are evaluating vaccines in combination with immune checkpoint inhibitors. Preliminary data from these trials have been promising and are offering an exciting glimpse at the future of immunotherapy for this disease.

The Role of Adaptive Immunity in the Efficacy of Targeted Cancer Therapies

Accumulating evidence indicates that the efficacy of tumor-targeted therapies relies on the host immune response, including targeted small-molecule and antibody approaches that were not previously thought to have an immune component. Here, we review the current understanding of how targeted therapies on tumor cells could have a major impact on the immune response, and how this relates to the therapeutic efficacy of these approaches. In this context, we evaluate different strategies that combine targeted therapies with immunotherapy approaches, and discuss past and ongoing clinical trials. We highlight gaps in knowledge, and argue that significant progress for combined therapies will require a better understanding of the complex interactions between immune cells, the tumor, and the tumor microenvironment (TME) in different cancer settings.

Phase 1 Dose-Escalation Study with LEC/chTNT-3 and Toceranib Phosphate (Palladia®) in Dogs with Spontaneous Malignancies

OBJECTIVES

LEC chemokine promotes TH1 responses and recruits immune cells to inflammatory sites. By linking LEC to an antibody targeting tumor necrosis, LEC/chTNT-3 can be used for the immunotherapeutic treatment of tumors. The primary objective of this study was to determine the safety profile of LEC/chTNT-3 and toceranib phosphate (Palladia^®) combination therapy in dogs with spontaneous malignancies. Secondary purpose was to determine objective responses to treatment.

METHODS

Twenty-three dogs with cancer were enrolled, covering nine different malignancies. In this dose escalation study, dogs received LEC/chTNT-3 for five days, and toceranib every 48 hours for the remainder of the study. Dogs received physical exams, chemistry panel, urinalysis, and complete blood counts on days 0, 10, 28 of the study, and every 6-8 weeks thereafter.

RESULTS

Lethargy was noted in 13% dogs. There were no statistical differences in the prevalence of anorexia, diarrhea, thrombocytopenia, renal toxicity, or hepatic toxicity before or during the study. There were trends in increases in the prevalence of vomiting, lymphopenia, and neutropenia (all grade 2 or lower, p=0.07) over the initial 28 days of the study. By day 28, 10% of dogs had partial responses, 58% had stable disease, and 32% had progressive disease.

CONCLUSIONS

LEC/chTNT-3 and toceranib were well tolerated. This combination therapy showed some biological activity against a variety of cancers at a low dose and short duration of LEC/chTNT-3 administration.