TG1042 (Adenovirus-interferon-γ) in primary cutaneous B-cell lymphomas: a phase II clinical trial

Targeting natural killer cells: from basic biology to clinical application in hematologic malignancies

Natural killer (NK) cell belongs to innate lymphoid cell family that contributes to host immunosurveillance and defense without pre-immunization. Emerging studies have sought to understand the underlying mechanism behind NK cell dysfunction in tumor environments, and provide numerous novel therapeutic targets for tumor treatment. Strategies to enhance functional activities of NK cell have exhibited promising efficacy and favorable tolerance in clinical treatment of tumor patients, such as immune checkpoint blockade (ICB), chimeric antigen receptor NK (CAR-NK) cell, and bi/trispecific killer cell engager (BiKE/TriKE). Immunotherapy targeting NK cell provides remarkable advantages compared to T cell therapy, including a decreased rate of graft versus-host disease (GvHD) and neurotoxicity. Nevertheless, advanced details on how to support the maintenance and function of NK cell to obtain better response rate and longer duration still remain to be elucidated. This review systematically summarizes the profound role of NK cells in tumor development, highlights up-to-date advances and current challenges of therapy targeting NK cell in the clinical treatment of hematologic malignancies.

The Clinical Advances of Oncolytic Viruses in Cancer Immunotherapy

A promising future for oncology treatment has been brought about by the emergence of a novel approach utilizing oncolytic viruses in cancer immunotherapy. Oncolytic viruses are viruses that have been exploited genetically to assault malignant cells and activate a robust immune response. Several techniques have been developed to endow viruses with an oncolytic activity through genetic engineering. For instance, redirection capsid modification, stimulation of anti-neoplastic immune response, and genetically arming viruses with cytokines such as IL-12. Oncolytic viral clinical outcomes are sought after, particularly in more advanced cancers. The effectiveness and safety profile of the oncolytic virus in clinical studies with or without the combination of standard treatment (chemotherapy, radiotherapy, or primary excision) has been assessed using response evaluation criteria in solid tumors (RECIST). This review will comprehensively outline the most recent clinical applications and provide the results from various phases of clinical trials in a variety of cancers in the latest published literature.

Darby J, Lyons AB, L. Patchett A, Lisowski L, Liu GS, S. Flies A. A human adenovirus encoding IFN-γ can transduce Tasmanian devil facial tumour cells and upregulate MHC-I

The devil facial tumour disease (DFTD) has led to a massive decline in the wild Tasmanian devil (Sarcophilus harrisii) population. The disease is caused by two independent devil facial tumours (DFT1 and DFT2). These transmissible cancers have a mortality rate of nearly 100 %. An adenoviral vector-based vaccine has been proposed as a conservation strategy for the Tasmanian devil. This study aimed to determine if a human adenovirus serotype 5 could express functional transgenes in devil cells. As DFT1 cells do not constitutively express major histocompatibility complex class I (MHC-I), we developed a replication-deficient adenoviral vector that encodes devil interferon gamma (IFN-γ) fused to a fluorescent protein reporter. Our results show that adenoviral-expressed IFN-γ was able to stimulate upregulation of beta-2 microglobulin, a component of MHC-I, on DFT1, DFT2 and devil fibroblast cell lines. This work suggests that human adenoviruses can serve as a vaccine platform for devils and potentially other marsupials.

Update in Diagnosis and Management of Primary Cutaneous B-Cell Lymphomas

Primary cutaneous lymphomas are a rare group of diseases, with an estimated incidence of 0.5-1 case per 100,000 people per year. Primary cutaneous B-cell lymphomas (pCBCLs) represent 25-30% of all primary cutaneous lymphomas. There are three main subtypes of pCBCL: primary cutaneous marginal zone lymphoma, primary cutaneous follicle center lymphoma, and primary cutaneous diffuse large B-cell lymphoma, leg type. Cutaneous B-cell lymphomas have a broad spectrum of clinical presentations, which makes diagnostic and therapeutic strategies challenging. To date, treatment recommendations for cutaneous B-cell lymphomas have been largely based on small retrospective studies and institutional experience. Recently, the pharmacotherapeutic landscape has expanded to include drugs that may modify the underlying disease pathology of pCBCLs, representing new therapeutic modalities for this rare group of diseases. Novel therapies used for other systemic B-cell lymphomas show promise for the treatment of pCBCLs and are being increasingly considered. These new therapies are divided into five main groups: monoclonal antibodies, immune checkpoint inhibitors, small-molecule inhibitors, bispecific T-cell engaging, and chimeric antigen receptor T cell. In this review, we discuss the clinical, histopathological, molecular, and cytogenetic features of the most common pCBCL subtypes with a focus on current and innovative therapeutic developments in their management. These emerging treatment strategies for B-cell lymphomas and cutaneous B-cell lymphomas may represent novel first-line options for the management of these rare diseases.

Engineering interferons and interleukins for cancer immunotherapy

Cytokines are a class of potent immunoregulatory proteins that are secreted in response to various stimuli and act locally to regulate many aspects of human physiology and disease. Cytokines play important roles in cancer initiation, progression, and elimination, and thus, there is a long clinical history associated with the use of recombinant cytokines to treat cancer. However, the use of cytokines as therapeutics has been limited by cytokine pleiotropy, complex biology, poor drug-like properties, and severe dose-limiting toxicities. Nevertheless, cytokines are crucial mediators of innate and adaptive antitumor immunity and have the potential to enhance immunotherapeutic approaches to treat cancer. Development of immune checkpoint inhibitors and combination immunotherapies has reinvigorated interest in cytokines as therapeutics, and a variety of engineering approaches are emerging to improve the safety and effectiveness of cytokine immunotherapy. In this review we highlight recent advances in cytokine biology and engineering for cancer immunotherapy.

Alphavirus-Driven Interferon Gamma (IFNg) Expression Inhibits Tumor Growth in Orthotopic 4T1 Breast Cancer Model

Interferon gamma (IFNg) is a pleiotropic cytokine that can potentially reprogram the tumor microenvironment; however, the antitumor immunomodulatory properties of IFNg still need to be validated due to variable therapeutic outcomes in preclinical and clinical studies. We developed a replication-deficient Semliki Forest virus vector expressing IFNg (SFV/IFNg) and evaluated its immunomodulatory antitumor potential in vitro in a model of 3D spheroids and in vivo in an immunocompetent 4T1 mouse breast cancer model. We demonstrated that SFV-derived, IFN-g-stimulated bone marrow macrophages can be used to acquire the tumoricidal M1 phenotype in 3D nonattached conditions. Coculturing SFV/IFNg-infected 4T1 spheroids with BMDMs inhibited spheroid growth. In the orthotopic 4T1 mouse model, intratumoral administration of SFV/IFNg virus particles alone or in combination with the Pam3CSK4 TLR2/1 ligand led to significant inhibition of tumor growth compared to the administration of the control SFV/Luc virus particles. Analysis of the composition of intratumoral lymphoid cells isolated from tumors after SFV/IFNg treatment revealed increased CD4⁺ and CD8⁺ and decreased T-reg (CD4⁺/CD25⁺/FoxP3⁺) cell populations. Furthermore, a significant decrease in the populations of cells bearing myeloid cell markers CD11b, CD38, and CD206 was observed. In conclusion, the SFV/IFNg vector induces a therapeutic antitumor T-cell response and inhibits myeloid cell infiltration in treated tumors.

Suppression effect of a dual cancer-specific oncolytic adenovirus on luciferase-labeled human melanoma cells in vitro and in vivo

BACKGROUND

To explore the suppressive effect of Apoptin-loaded oncolytic adenovirus (Ad-VT) on luciferase-labeled human melanoma cells in vitro and in vivo.

METHODS

The stable luciferase-expressing human melanoma cells A375-luc or M14-luc were obtained by transfecting the plasmid pGL4.51 and selection with G418, followed by luciferase activity, genetic stability and bioluminescence intensity assays. In vitro, the inhibitory effects of Ad-VT on A375-luc or M14-luc were evaluated using the MTS cell proliferation, FITC-Annexin V apoptosis detection, transwell migration, Matrigel invasion and scratch assays. The inhibition pathway in Ad-VT-infected A375-luc and M14-luc cells were analyzed by JC-1 staining and Western-blot detection of mitochondrial apoptosis-related proteins. In vivo, the suppressive effects of Ad-VT on A375-luc or M14-luc were assessed by living imaging technology, tumor volume, bioluminescence intensity, survival curves and immunohistochemical analysis of the tumors from the xenograft tumor model BALB/c nude mice.

RESULTS

The growth and migration of A375-luc and M14-luc were significantly inhibited by Ad-VT in vitro. The evaluations of A375-luc and M14-luc tumor models in BALB/c nude mice were successfully performed using living imaging technology. Ad-VT had an anti-tumor effect by reducing tumor growth and increasing survival in vivo. Ad-VT significantly changed the mitochondrial membrane potential by triggering the the mitochondrial release of apoptosis-related proteins, AIF (apoptosis inducing factor), ARTS (Apoptosis-Related Proteins), and Cyto-c (cytochrome c) from the mitochondria.

CONCLUSION

Ad-VT reduced the mitochondrial membrane potential in A375-luc or M14-luc cells and induced the mitochondrial release of AIF, ARTS and Cyto-C. Ad-VT induced apoptosis in A375-luc or M14-luc cells via the mitochondrial apoptotic pathway.

Combinatorial Approaches for Cancer Treatment Using Oncolytic Viruses: Projecting the Perspectives through Clinical Trials Outcomes

Recent cancer immunotherapy breakthroughs have fundamentally changed oncology and revived the fading hope for a cancer cure. The immune checkpoint inhibitors (ICI) became an indispensable tool for the treatment of many malignant tumors. Alongside ICI, the application of oncolytic viruses in clinical trials is demonstrating encouraging outcomes. Dozens of combinations of oncolytic viruses with conventional radiotherapy and chemotherapy are widely used or studied, but it seems quite complicated to highlight the most effective combinations. Our review summarizes the results of clinical trials evaluating oncolytic viruses with or without genetic alterations in combination with immune checkpoint blockade, cytokines, antigens and other oncolytic viruses as well. This review is focused on the efficacy and safety of virotherapy and the most promising combinations based on the published clinical data, rather than presenting all oncolytic virus variations, which are discussed in comprehensive literature reviews. We briefly revise the research landscape of oncolytic viruses and discuss future perspectives in virus immunotherapy, in order to provide an insight for novel strategies of cancer treatment.

Dermatological Considerations in the Diagnosis and Treatment of Marginal Zone Lymphomas

Primary cutaneous marginal zone lymphoma (PC-MZL) is a B-cell lymphoma arising in the skin. Although it is a rare disease, PC-MZL accounts for 20–40% of all primary cutaneous B-cell lymphoma in Western Countries. The aetiology and the pathogenesis of PC-MZL are poorly understood, as it generally lacks the chromosomal translocations most typically present in marginal zone lymphomas of other sites. The diagnosis of PC-MZL may be challenging, due to the rarity of the disease, and needs the competence of different professional figures, including the dermatologist and the pathologist. Furthermore, the management of the patient after the diagnosis is complex and involves the dermatologist, the haematologist, the surgeon, the radiotherapist and the radiologist. The aim of this review is to describe the clinical and histological findings for the diagnosis of PC-MZL, and the state of art for the management of the patient.

Innovative Therapeutic Approaches in Primary Cutaneous B Cell Lymphoma

Background: Primary cutaneous B-cell lymphomas (pCBCL) include an infrequent group of non-Hodgkin lymphomas that are limited to skin sites at the time of diagnosis. They comprise roughly 20–25% of all cutaneous lymphomas and are subdivided into primary cutaneous marginal zone lymphoma (PCMZL), primary cutaneous follicle center lymphoma (PCFCL), and primary cutaneous diffuse large cell B cell lymphoma, leg type (PCDLCBCL, LT). The first two show a rather indolent course while PCDLCBCL, LT carries a worse prognosis. Intravascular large cell B-cell lymphoma is the most infrequent subtype, and its therapy is not covered in this review.

Topical Therapy: For solitary, single-site PCMZL and PCFCL, several topical treatment options exist. They include, but are not limited to, excision, radiotherapy, and intralesional therapies, discussed in this review. However, in selected cases, even “watchful waiting” is reasonable.

Systemic Therapy: Indolent types of pCBCL rarely require systemic treatment. However, in extended cases and more importantly DLCBCL, LT, systemic treatment is the first choice. Monoclonal anti-CD20-antibody rituximab is often used as monotherapy in PCMZL and PCFCL or combined with chemotherapy in PCDLBCL, LT. Newer options are monoclonal anti-CD40 antibody dacetuzumab, anti-PD-1 and anti-PD-L1 checkpoint inhibitors, and Bruton tyrosine kinase inhibitors.

Conclusion: Indolent pCBCL are treated with a risk-adapted strategy using intralesional steroids, RT, and interferon-α as first-line treatments. Relapsing cases may profit from rituximab. In aggressive PCDLCBCL, LT, rituximab with polychemotherapy is recommended. Innovative therapies include intralesional oncolytic virotherapy, systemic monoclonal antibodies, and small molecules.

Human intratumoral therapy: Linking drug properties and tumor transport of drugs in clinical trials

Cancer therapies aim to kill tumor cells directly or engage the immune system to fight malignancy. Checkpoint inhibitors, oncolytic viruses, cell-based immunotherapies, cytokines, and adjuvants have been applied to prompt the immune system to recognize and attack cancer cells. However, systemic exposure of cancer therapies can induce unwanted adverse events. Intratumoral administration of potent therapies utilizes small amounts of drugs, in an effort to minimize systemic exposure and off-target toxicities. Here, we discuss the properties of the tumor microenvironment and transport considerations for intratumoral drug delivery. Specifically, we consider various tumor tissue factors and physicochemical factors that can affect tumor retention after intratumoral injection. We also review approved and clinical-stage intratumoral therapies and consider how the molecular and biophysical properties (e.g. size and charge) of these therapies influences intratumoral transport (e.g. tumor retention and cellular uptake). Finally, we offer a critical review and highlight several emerging approaches to promote tumor retention and limit systemic exposure of potent intratumoral therapies.

Diagnosis and Treatment of Primary Cutaneous B-Cell Lymphomas: State of the Art and Perspectives

Primary cutaneous B-cell lymphomas are rare entities that develop primarily in the skin. They constitute a heterogeneous group that represents around a quarter of primary cutaneous lymphomas. The 2018 update of the World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) classification differentiates primary cutaneous marginal zone lymphoma and primary cutaneous follicle center lymphoma with an indolent course from primary cutaneous diffuse large B-cell lymphoma, leg type with an aggressive behavior. The broad spectrum of clinical presentations and the disease course marked by frequent relapses are diagnostic and therapeutic challenges. The classification of these diseases has been refined in recent years, which allows to better define their immunopathogenesis and specific management. In the present article, we review the main clinico-biological characteristics and the current therapeutic options of these three main subsets. Based on the recent therapeutic advances in nodal B-cell lymphomas, we focus on the development of novel treatment options applicable to primary cutaneous B-cell lymphomas, including targeted therapies, combination treatments and immunotherapeutic approaches, and cover basic, translational and clinical aspects aiming to improve the treatment of cutaneous B-cell lymphomas.

Diagnosis and Management of Cutaneous B-Cell Lymphomas

Primary cutaneous B-cell lymphomas are a group of diseases with indolent and aggressive behavior. The goal of the initial workup is to evaluate for systemic involvement, provide adequate staging, and guide therapy. Histopathological studies are a critical part of the workup for classification of these lymphomas because they are similar to their nodal counterparts. There are limited data for treatment guidelines, and thus, therapy differs among institutions. Overall, localized therapies are preferred for indolent types and chemotherapy or immunotherapy for the aggressive forms.

Chitosan/poly(γ-glutamic acid) nanoparticles incorporating IFN-γ for immune response modulation in the context of colorectal cancer

IFN-γ therapy has been approved by the Food and Drug Administration (FDA) for the treatment of chronic granulomatous disease and severe malignant osteopetrosis. Despite the promising IFN-γ-based therapeutic applications, its limited success in clinical trials is related with limitations inherent to its molecular properties and with the difficulties to deliver it locally or with adequate periodicity to achieve a therapeutic effect. We have previously shown that chitosan (Ch)/poly(γ-glutamic acid) (γ-PGA) nanoparticles (NPs) are immunostimulatory, impairing colorectal cancer cell invasion. Ch is a biocompatible cationic polysaccharide extensively studied and already approved for biomedical applications while γ-PGA is a poly(amino acid), biodegradable and negatively charged. Here, we evaluated the potential of Ch/γ-PGA NPs as vehicles for IFN-γ and their ability to modulate immune cells' phenotype. In this study, Ch/IFN-γ/γ-PGA nanoparticles (IFN-γ-NPs) prepared by a co-acervation method, presenting a size of approximately 180 nm and a low polydispersity index, were tested for their immunomodulatory activity. These IFN-γ-NPs induced an immunostimulatory profile on dendritic cells (DCs) with increased cell surface costimulatory molecules and secretion of pro-inflammatory cytokines, including IL-6, IL-12p40 and TNF-α. IFN-γ-NPs also modulated the IL-10-stimulated macrophage profile, increasing their ability to secrete the pro-inflammatory cytokines IL-6, IL-12p40 and TNF-α. Concomitantly, these phenotypic alterations enhanced T cell proliferation. In addition, the ability of DCs and macrophages to induce colorectal cancer cell invasion was hampered in the presence of IFN-γ-NPs. Although the major observations were mediated by Ch/γ-PGA NPs, the incorporation of IFN-γ into NPs potentiated the expression of CD40 and CD86, and the impairment of colorectal cancer cell invasion. This work bridges the previously reported immunostimulatory capacity of Ch/γ-PGA NPs with their potential as carriers for immunomodulatory molecules, like IFN-γ, opening new avenues for their use in clinical settings.

An alphavirus-based therapeutic cancer vaccine: from design to clinical trial

Cancer immunotherapy has greatly advanced in recent years. Most immunotherapeutic strategies are based on the use of immune checkpoint blockade to unleash antitumor immune responses or on the induction or adoptive transfer of immune effector cells. We aim to develop therapeutic vaccines based on recombinant Semliki Forest virus vectors to induce tumor-specific effector immune cells. In this review, we describe our ongoing work on SFV-based vaccines targeted against human papillomavirus- and hepatitis C virus-related infections and malignancies, focusing on design, delivery, combination strategies, preclinical efficacy and product development for a first-in-man clinical trial with an HPV-specific vaccine.

Effect of Genetic Modifications on Physical and Functional Titers of Adenoviral Cancer Gene Therapy Constructs

After the discovery and characterization of the adenovirus in the 1950s, this prevalent cause of the common cold and other usually mild diseases has been modified and utilized in biomedicine in several ways. To date, adenoviruses are the most frequently used vectors and therapeutic (e.g., oncolytic) agents with a number of beneficial features. They infect both dividing and nondividing cells, enable high-level, transient protein expression, and are easy to amplify to high concentrations. As an important and versatile research tool, it is of essence to understand the limits and advantages that genetic modification of adenovirus vectors may entail. Therefore, a retrospective analysis was performed of adenoviral gene therapy constructs produced in the same laboratory with similar methods. The aim was to assess the impact of various modifications on the physical and functional titer of the virus. It was found that genome size (designed within "the 105% golden rule") did not significantly affect the physical titer of the adenovirus preparations, regardless of the type of transgene (e.g., immunostimulatory vs. other), number of engineered changes, and size of the mutated virus genome. One statistically significant exception was noted, however. Chimeric adenoviruses (5/3) had a slightly lower physical titer compared to Ad5-based viruses, although a trend for the opposite was true for functional titers. Thus, 5/3 chimeric viruses may in fact be appealing from a safety versus efficacy viewpoint. Armed viruses had lower functional and physical titers than unarmed viruses, while five genomic modifications started to decrease functional titer. Importantly, even highly modified armed viruses generally had good titers compatible with clinical testing. In summary, this paper shows the plasticity of adenovirus for various vector, oncolytic, and armed oncolytic uses. These results inform future generations of adenovirus-based drugs for human use. This information is directly transferable to academic laboratories and the biomedical industry involved in vector design and production optimization.

The Interferon-Gamma Paradox in Cancer

Interferon-gamma (IFNG) has long been implicated as a central orchestrator of antitumor immune responses in the elimination stage of the immunoediting paradigm. However, mounting evidence suggests that IFNG may also have important and significant protumor roles to play in the equilibrium and escape phases through its regulatory effects on immunoevasive functions that promote tumorigenesis. These seemingly contradictory effects of IFNG undoubtedly play profound roles in not only the activation of inflammatory response to cancer but also in the determination of its outcome. In the face of the recent explosion of anticancer immunotherapeutic strategies in the clinic, it is critical that a complete understanding is achieved of the underpinnings of the mechanisms that determine the two faces of IFNG signaling in cancer. Here, the current state of this dichotomy is reviewed.

The Dark Side of IFN-γ: Its Role in Promoting Cancer Immunoevasion

Interferon-γ (IFN-γ) is a pleiotropic cytokine that has long been praised as an important effector molecule of anti-tumor immunity, capable of suppressing tumor growth through various mechanisms. On the contrary to such a bright side of IFN-γ, it has also been involved in promoting an outgrowth of tumor cells with immunoevasive phenotype suggesting an existence of a dark "tumor-promoting" side effect of IFN-γ. In this review, we will summarize this multi-functional role of IFN-γ in tumor context, how it promotes changes in tumor phenotype towards increased fitness for growth in immunocompetent host. Furthermore, we summarize how IFN-γ is involved in homeostatic or cancer-triggered mechanisms to establish an immunosuppressive tumor microenvironment.

Hitting the nail on the head: combining oncolytic adenovirus-mediated virotherapy and immunomodulation for the treatment of glioma

Glioblastoma is a highly aggressive malignant brain tumor with a poor prognosis and the median survival 14.6 months. Immunomodulatory proteins and oncolytic viruses represent two treatment approaches that have recently been developed for patients with glioblastoma that could extend patient survival and result in better treatment outcomes for patients with this disease. Together, these approaches could potentially augment the treatment efficacy and strength of these anti-tumor therapies. In addition to oncolytic activities, this combinatory approach introduces immunomodulation locally only where cancerous cells are present. This thereby results in the change of the tumor microenvironment from immune-suppressive to immune-vulnerable via activation of cytotoxic T cells or through the removal of glioma cells immune-suppressive capability. This review discusses the strengths and weaknesses of adenoviral oncolytic therapy, and highlights the genetic modifications that result in more effective and targeted viral agents. Additionally, the mechanism of action of immune-activating agents is described and the results of previous clinical trials utilizing these treatments in other solid tumors are reviewed. The feasibility, synergy, and limitations for treatments that combine these two approaches are outlined and areas for which more work is needed are considered.

Interferon-alpha-based immunotherapies in the treatment of B cell-derived hematologic neoplasms in today's treat-to-target era

B cell lymphoma and multiple myeloma (MM) are the most common hematological malignancies which benefit from therapeutic monoclonal antibodies (mAbs)-based immunotherapies. Despite significant improvement on patient outcome following the use of novel therapies for the past decades, curative treatment is unavailable for the majority of patients. For example, the 5-year survival of MM is currently less than 50%. In the 1980s, interferon-α was used as monotherapy in newly diagnosed or previously treated MM with an overall response rate of 15-20%. Noticeably, a small subset of patients who responded to long-term interferon-α further achieved sustained complete remission. Since 1990, interferon-α-containing regimens have been used as a central maintenance strategy for patients with MM. However, the systemic administration of interferon-α was ultimately limited by its pronounced toxicity. To address this, the selective mAb-mediated delivery of interferon-α has been developed to enhance specific killing of MM and B-cell malignant cells. As such, targeted interferon-α therapy may improve therapeutic window and sustain responses, while further overcoming suppressive microenvironment. This review aims to reinforce the role of interferon-α by consolidating our current understanding of targeting interferon-α with tumor-specific mAbs for B cell lymphoma and myeloma.

Interferon-γ and Tumor Necrosis Factor-α Polarize Bone Marrow Stromal Cells Uniformly to a Th1 Phenotype

Activated T cells polarize mesenchymal stromal cells (MSCs) to a proinflammatory Th1 phenotype which likely has an important role in amplifying the immune response in the tumor microenvironment. We investigated the role of interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), two factors produced by activated T cells, in MSC polarization. Gene expression and culture supernatant analysis showed that TNF-α and IFN-γ stimulated MSCs expressed distinct sets of proinflammatory factors. The combination of IFN-γ and TNF-α was synergistic and induced a transcriptome most similar to that found in MSCs stimulated with activated T cells and similar to that found in the inflamed tumor microenvironment; a Th1 phenotype with the expression of the immunosuppressive factors IL-4, IL-10, CD274/PD-L1 and indoleamine 2,3 dioxygenase (IDO). Single cell qRT-PCR analysis showed that the combination of IFN-γ and TNF-α polarized uniformly to this phenotype. The combination of IFN-γ and TNF-α results in the synergist uniform polarization of MSCs toward a primarily Th1 phenotype. The stimulation of MSCs by IFN-γ and TNF-α released from activated tumor infiltrating T cells is likely responsible for the production of many factors that characterize the tumor microenvironment.