Aberrant Expression of MHC Class II in Melanoma Attracts Inflammatory Tumor-Specific CD4+ T- Cells, Which Dampen CD8+ T-cell Antitumor Reactivity

Tumor Necrosis Factor α Blockade: An Opportunity to Tackle Breast Cancer

Breast cancer is the most frequently diagnosed cancer and the principal cause of mortality by malignancy in women and represents a main problem for public health worldwide. Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine whose expression is increased in a variety of cancers. In particular, in breast cancer it correlates with augmented tumor cell proliferation, higher malignancy grade, increased occurrence of metastasis and general poor prognosis for the patient. These characteristics highlight TNFα as an attractive therapeutic target, and consequently, the study of soluble and transmembrane TNFα effects and its receptors in breast cancer is an area of active research. In this review we summarize the recent findings on TNFα participation in luminal, HER2-positive and triple negative breast cancer progression and metastasis. Also, we describe TNFα role in immune response against tumors and in chemotherapy, hormone therapy, HER2-targeted therapy and anti-immune checkpoint therapy resistance in breast cancer. Furthermore, we discuss the use of TNFα blocking strategies as potential therapies and their clinical relevance for breast cancer. These TNFα blocking agents have long been used in the clinical setting to treat inflammatory and autoimmune diseases. TNFα blockade can be achieved by monoclonal antibodies (such as infliximab, adalimumab, etc.), fusion proteins (etanercept) and dominant negative proteins (INB03). Here we address the different effects of each compound and also analyze the use of potential biomarkers in the selection of patients who would benefit from a combination of TNFα blocking agents with HER2-targeted treatments to prevent or overcome therapy resistance in breast cancer.

TNF-α inhibitor reduces drug-resistance to anti-PD-1: A mathematical model

Drug resistance is a primary obstacle in cancer treatment. In many patients who at first respond well to treatment, relapse occurs later on. Various mechanisms have been explored to explain drug resistance in specific cancers and for specific drugs. In this paper, we consider resistance to anti-PD-1, a drug that enhances the activity of anti-cancer T cells. Based on results in experimental melanoma, it is shown, by a mathematical model, that resistances to anti-PD-1 can be significantly reduced by combining it with anti-TNF-α. The model is used to simulate the efficacy of the combined therapy with different range of doses, different initial tumor volume, and different schedules. In particular, it is shown that under a course of treatment with 3-week cycles where each drug is injected in the first day of either week 1 or week 2, injecting anti-TNF-α one week after anti-PD-1 is the most effective schedule in reducing tumor volume.

Lymphocyte-activation gene 3 (LAG3): The next immune checkpoint receptor

Immune checkpoint therapy has revolutionized cancer treatment by blocking inhibitory pathways in T cells that limits the an effective anti-tumor immune response. Therapeutics targeting CTLA-4 and PD1/PDL1 have progressed to first line therapy in multiple tumor types with some patients exhibiting tumor regression or remission. However, the majority of patients do not benefit from checkpoint therapy emphasizing the need for alternative therapeutic options. Lymphocyte Activation Gene 3 (LAG3) or CD223 is expressed on multiple cell types including CD4⁺ and CD8⁺ T cells, and T_regs, and is required for optimal T cell regulation and homeostasis. Persistent antigen-stimulation in cancer or chronic infection leads to chronic LAG3 expression, promoting T cell exhaustion. Targeting LAG3 along with PD1 facilitates T cell reinvigoration. A substantial amount of pre-clinical data and mechanistic analysis has led to LAG3 being the third checkpoint to be targeted in the clinic with nearly a dozen therapeutics under investigation. In this review, we will discuss the structure, function and role of LAG3 in murine and human models of disease, including autoimmune and inflammatory diseases, chronic viral and parasitic infections, and cancer, emphasizing new advances in the development of LAG3-targeting immunotherapies for cancer that are currently in clinical trials.

Reverting Immune Suppression to Enhance Cancer Immunotherapy

Tumors employ strategies to escape immune control. The principle aim of most cancer immunotherapies is to restore effective immune surveillance. Among the different processes regulating immune escape, tumor microenvironment-associated soluble factors, and/or cell surface-bound molecules are mostly responsible for dysfunctional activity of tumor-specific CD8⁺T cells. These dynamic immunosuppressive networks prevent tumor rejection at several levels, limiting also the success of immunotherapies. Nevertheless, the recent clinical development of immune checkpoint inhibitors or of molecules modulating cellular targets and immunosuppressive enzymes highlights the great potential of approaches based on the selective disruption of immunosuppressive networks. Currently, the administration of different categories of immunotherapy in combination regimens is the ultimate modality for impacting the survival of cancer patients. With the advent of immune checkpoint inhibitors, designed to mount an effective antitumor immune response, profound changes occurred in cancer immunotherapy: from a global stimulation of the immune system to a specific targeting of an immune component. This review will specifically highlight the players, the mechanisms limiting an efficient antitumor response and the current immunotherapy modalities tailored to target immune suppressive pathways. We also discuss the ongoing challenges encountered by these strategies and provide suggestions for circumventing hurdles to new immunotherapeutic approaches, including the use of relevant biomarkers in the optimization of immunotherapy regimens and the identification of patients who can benefit from defined immune-based approaches.

The Major Histocompatibility Complex Class II-CD4 Immunologic Synapse in Alcoholic Hepatitis and Autoimmune Liver Pathology: The Role of Aberrant Major Histocompatibility Complex Class II in Hepatocytes

The major histocompatibility complex class II (MHC II)-CD4 immunologic synapse is classically described between the T-cell receptor of CD4-positive lymphocytes and MHC II on antigen-presenting cells. This interaction and others between surrounding costimulatory and checkpoint molecules promote differentiation of naïve CD4 T lymphocytes into helper T cells subtypes, including types 1, 2, and 17 helper T cells, that have more tailored immunologic responses. Although MHC II is mainly produced by professional antigen-presenting cells, it can be aberrantly produced by other cell types, including hepatocytes in various liver pathologies, such as autoimmune hepatitis and alcoholic hepatitis. This can lead to direct targeting of hepatocytes by CD4-positive lymphocytes, which form an immunologic synapse with the hepatocyte. The lymphocytes internalize the MHC II-CD4 complexes in a phagocytosis-like mechanism and in the process eat the hepatocyte piece by piece. We review the evidence for this mechanism and the role of these autoimmune responses in various liver diseases, including alcoholic hepatitis, autoimmune hepatitis, and primary biliary cirrhosis. The role of aberrant MHC II in malignancy, including hepatocellular carcinoma, is also reviewed. Further understanding of this mechanism can lead to better understanding of the immune mechanisms involved in these liver pathologies, with potential diagnostic and therapeutic applications.

Inhibitory receptors and ligands beyond PD-1, PD-L1 and CTLA-4: breakthroughs or backups

Although immunotherapeutics targeting the inhibitory receptors (IRs) CTLA-4, PD-1 or PD-L1 have made substantial clinical progress in cancer, a considerable proportion of patients remain unresponsive to treatment. Targeting novel IR-ligand pathways in combination with current immunotherapies may improve clinical outcomes. New clinical immunotherapeutics target T cell-expressed IRs (LAG-3, TIM-3 and TIGIT) as well as inhibitory ligands in the B7 family (B7-H3, B7-H4 and B7-H5), although many of these targets have complex biologies and unclear mechanisms of action. With only modest clinical success in targeting these IRs, current immunotherapeutic design may not be optimal. This Review covers the biology of targeting novel IR-ligand pathways and the current clinical status of their immunotherapeutics, either as monotherapy or in combination with antibody to PD-1 or to its ligand PD-L1. Further understanding of the basic biology of these targets is imperative to the development of effective cancer immunotherapies.

MERTK Acts as a Costimulatory Receptor on Human CD8+ T Cells

The TAM family of receptor tyrosine kinases (TYRO3, AXL, and MERTK) is known to be expressed on antigen-presenting cells and function as oncogenic drivers and as inhibitors of inflammatory responses. Both human and mouse CD8⁺ T cells are thought to be negative for TAM receptor expression. In this study, we show that T-cell receptor (TCR)-activated human primary CD8⁺ T cells expressed MERTK and the ligand PROS1 from day 2 postactivation. PROS1-mediated MERTK signaling served as a late costimulatory signal, increasing proliferation and secretion of effector and memory-associated cytokines. Knockdown and inhibition studies confirmed that this costimulatory effect was mediated through MERTK. Transcriptomic and metabolic analyses of PROS1-blocked CD8⁺ T cells demonstrated a role of the PROS1-MERTK axis in differentiation of memory CD8⁺ T cells. Finally, using tumor-infiltrating lymphocytes (TIL) from melanoma patients, we show that MERTK signaling on T cells improved TIL expansion and TIL-mediated autologous cancer cell killing. We conclude that MERTK serves as a late costimulatory signal for CD8⁺ T cells. Identification of this costimulatory function of MERTK on human CD8⁺ T cells suggests caution in the development of MERTK inhibitors for hematologic or solid cancer treatment.

Implications of altered O-glycosylation in tumour immune evasion

Aberrant glycosylation on tumour cells has been implicated in tumour immune modulation. A recent article published in The Journal of Biochemistry (Sutoh Yoneyama et al., A mechanism for evasion of CTL immunity by altered O-glycosylation of HLA class I, J. Biochem. 2017;161:479-492) showed that bladder cancer cells evaded cytotoxic T lymphocyte-mediated antitumour immunity by a novel mechanism involving the loss of Core 2 structures on human leukocyte antigen Class I O-glycans and subsequent impairment of galectin-glycan lattice formation. The immunosuppressive action of O-glycans on natural killer cell-mediated tumour immunity is also considered an immune evasion system. Furthermore, sialylated O-glycans have been proposed to play a central role in tumour immune escape by modulating the production of immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. Therefore, a better understanding of how alterations in O-glycosylation influence tumour immune evasion will enable the development of novel and more effective therapeutic options for cancer treatment.

Tumour-reactive T cell subsets in the microenvironment of ovarian cancer

BACKGROUND

Solid malignancies are frequently infiltrated with T cells. The success of adoptive cell transfer (ACT) with expanded tumour-infiltrating lymphocytes (TILs) in melanoma warrants its testing in other cancer types. In this preclinical study, we investigated whether clinical-grade TILs could be manufactured from ovarian cancer (OC) tumour specimens.

METHODS

Thirty-four tumour specimens were obtained from 33 individual patients with OC. TILs were analysed for phenotype, antigen specificity and functionality.

RESULTS

Minimally expanded TILs (Young TILs) were successfully established from all patients. Young TILs contained a high frequency of CD3⁺ cells with a variable CD4/CD8 ratio. TILs could be expanded to clinical numbers. Importantly, recognition of autologous tumour cells was demonstrated in TILs in >50% of the patients. We confirmed with mass spectrometry the presentation of multiple tumour antigens, including peptides derived from the cancer-testis antigen GAGE, which could be recognised by antigen-specific TILs. Antigen-specific TILs could be isolated and further expanded in vitro.

CONCLUSION

These findings support the hypothesis that patients with OC can benefit from ACT with TILs and led to the initiation of a pilot clinical trial at our institution .

TRIAL REGISTRATION

clinicaltrials.gov: NCT02482090.

Tumour-reactive T cell subsets in the microenvironment of ovarian cancer

BACKGROUND

Solid malignancies are frequently infiltrated with T cells. The success of adoptive cell transfer (ACT) with expanded tumour-infiltrating lymphocytes (TILs) in melanoma warrants its testing in other cancer types. In this preclinical study, we investigated whether clinical-grade TILs could be manufactured from ovarian cancer (OC) tumour specimens.

METHODS

Thirty-four tumour specimens were obtained from 33 individual patients with OC. TILs were analysed for phenotype, antigen specificity and functionality.

RESULTS

Minimally expanded TILs (Young TILs) were successfully established from all patients. Young TILs contained a high frequency of CD3+ cells with a variable CD4/CD8 ratio. TILs could be expanded to clinical numbers. Importantly, recognition of autologous tumour cells was demonstrated in TILs in >50% of the patients. We confirmed with mass spectrometry the presentation of multiple tumour antigens, including peptides derived from the cancer-testis antigen GAGE, which could be recognised by antigen-specific TILs. Antigen-specific TILs could be isolated and further expanded in vitro.

CONCLUSION

These findings support the hypothesis that patients with OC can benefit from ACT with TILs and led to the initiation of a pilot clinical trial at our institution .

TRIAL REGISTRATION

clinicaltrials.gov: NCT02482090.

Transient redirection of T cells for adoptive cell therapy with telomerase-specific T helper cell receptors isolated from long term survivors after cancer vaccination

Adoptive cell therapy (ACT) with retargeted T cells has produced remarkable clinical responses against cancer, but also serious toxicity. Telomerase is overexpressed in most cancers, but also expressed in some normal cells, raising safety concerns. We hypothesize that ACT with T-helper cell receptors may overcome tumour tolerance, mobilize host immune cells and induce epitope spreading, with limited toxicity. From long term survivors after cancer vaccination, we have isolated telomerase-specific T cell receptors (TCRs) from T-helper cells. Herein, we report the development of transient retargeting of T cells with mRNA-based TCRs. This strategy allows for safer clinical testing and meaningful dose escalation. DP4 is the most common HLA molecule. We cloned two telomerase-specific, DP4-restricted TCRs into the mRNA expression vector pCIpA102, together with the sorter/marker/suicide gene RQR8. Donor T cells were electroporated with mRNA encoding TCR_RQR8. The results showed that both TCR_RQR8 constructs were expressed in >90% of T cells. The transfected T cells specifically recognized the relevant peptide, as well as naturally processed epitopes from a 177aa telomerase protein fragment, and remained functional for six days. A polyfunctional and Th1-like cytokine profile was observed. The TCRs were functional in both CD4+and CD8+recipient T cells, even though DP4-restricted. The findings demonstrate that the cloned TCRs confer recipient T cells with the desired telomerase-specificity and functionality. Preclinical experiments may provide limited information on the efficacy and toxicity of T-helper TCRs, as these mobilize the host immune system. We therefore intend to use the mRNA-based TCRs for a first-in-man trial.

Differential effects of corticosteroids and anti-TNF on tumor-specific immune responses: implications for the management of irAEs

Up to 60% of patients treated with cancer immunotherapy develop severe or life threatening immune-related adverse events (irAEs). Immunosuppression with high dose corticosteroids, or tumor necrosis factor (TNF) antagonists in refractory cases, is the mainstay of treatment for irAEs. It is currently unknown what impact corticosteroids and anti-TNF have on the activity of antitumor T cells. In our study, the influence of clinically relevant doses of dexamethasone (corresponding to an oral dose of 10-125 mg prednisolone) and infliximab (anti-TNF) on the activation and killing ability of tumor-infiltrating lymphocytes (TILs) was tested in vitro. Overall, dexamethasone at low or intermediate/high doses impaired the activation (-46 and -62%, respectively) and tumor-killing ability (-48 and -53%, respectively) of tumor-specific TILs. In contrast, a standard clinical dose of infliximab only had a minor effect on T cell activation (-20%) and tumor killing (-10%). A 72-hr resting period after withdrawal of dexamethasone was sufficient to rescue the in vitro activity of TILs, while a short withdrawal did not result in a full rescue. In conclusion, clinically relevant doses of infliximab only had a minor influence on the activity of tumor-specific TILs in vitro, whereas even low doses of corticosteroids markedly impaired the antitumor activity of TILs. However, the activity of TILs could be restored after withdrawal of steroids. These data indirectly support steroid-sparing strategies and early initiation of anti-TNF therapy for the treatment of irAEs in immuno-oncology.

Loss of VGLL4 suppresses tumor PD-L1 expression and immune evasion

Targeting immune checkpoints, such as PD-L1 and its receptor PD-1, has opened a new avenue for treating cancers. Understanding the regulatory mechanism of PD-L1 and PD-1 will improve the clinical response rate and efficacy of PD-1/PD-L1 blockade in cancer patients and the development of combinatorial strategies. VGLL4 inhibits YAP-induced cell proliferation and tumorigenesis through competition with YAP for binding to TEADs. However, whether VGLL4 has a role in anti-tumor immunity is largely unknown. Here, we found that disruption of Vgll4 results in potent T cell-mediated tumor regression in murine syngeneic models. VGLL4 deficiency reduces PD-L1 expression in tumor cells. VGLL4 interacts with IRF2BP2 and promotes its protein stability through inhibiting proteasome-mediated protein degradation. Loss of IRF2BP2 results in persistent binding of IRF2, a transcriptional repressor, to PD-L1 promoter. In addition, YAP inhibits IFNγ-inducible PD-L1 expression partially through suppressing the expression of VGLL4 and IRF1 by YAP target gene miR-130a. Our study identifies VGLL4 as an important regulator of PD-L1 expression and highlights a central role of VGLL4 and YAP in the regulation of tumor immunity.

Cancer Cells Exploit Notch Signaling to Redefine a Supportive Cytokine Milieu

Notch signaling is a well-known key player in the communication between adjacent cells during organ development, when it controls several processes involved in cell differentiation. Notch-mediated communication may occur through the interaction of Notch receptors with ligands on adjacent cells or by a paracrine/endocrine fashion, through soluble molecules that can mediate the communication between cells at distant sites. Dysregulation of Notch pathway causes a number of disorders, including cancer. Notch hyperactivation may be caused by mutations of Notch-related genes, dysregulated upstream pathways, or microenvironment signals. Cancer cells may exploit this aberrant signaling to "educate" the surrounding microenvironment cells toward a pro-tumoral behavior. This may occur because of key cytokines secreted by tumor cells or it may involve the microenvironment through the activation of Notch signaling in stromal cells, an event mediated by a direct cell-to-cell contact and resulting in the increased secretion of several pro-tumorigenic cytokines. Up to now, review articles were mainly focused on Notch contribution in a specific tumor context or immune cell populations. Here, we provide a comprehensive overview on the outcomes of Notch-mediated pathological interactions in different tumor settings and on the molecular and cellular mediators involved in this process. We describe how Notch dysregulation in cancer may alter the cytokine network and its outcomes on tumor progression and antitumor immune response.

The Effect of Pembrolizumab in Absence of Programmed Death 1 Receptor

Tumor therapy has evolved greatly since the discovery of immunotherapies. New therapies permit targeted approach with less side effects. Immunotherapies target specific components recognized on tumor cells, such as Programmed death-1 (PD-1). Overexpression of PD-1 markers in solid gastrointestinal tumors is a consequence of deficiency in DNA mismatch repair mechanism. Pembrolizumab is an example of immunotherapy targeting PD-1. Pembrolizumab binding of PD-1 helps the immune system recognize tumor cells and initiate destruction cascade. We present a case of a PD-1 negative appendiceal tumor responding to pembrolizumab.

The opposing roles of CD4+ T cells in anti-tumour immunity

Cancer immunotherapy focuses mainly on anti-tumour activity of CD8+ cytotoxic T lymphocytes (CTLs). CTLs can directly kill all tumour cell types, provided they carry recognizable antigens. However, CD4+ T cells also play important roles in anti-tumour immunity. CD4+ T cells can either suppress or promote the anti-tumour CTL response, either in secondary lymphoid organs or in the tumour. In this review, we highlight opposing mechanisms of conventional and regulatory T cells at both sites. We outline how current cancer immunotherapy strategies affect both subsets and how selective modulation of each subset is important to maximize the clinical response of cancer patients.

Influence of ipilimumab on expanded tumour derived T cells from patients with metastatic melanoma

INTRODUCTION

Tumour infiltrating lymphocyte (TIL) based adoptive cell therapy (ACT) is a promising treatment for patients with advanced melanoma. Retrospective studies suggested an association between previous treatment with anti-CTLA-4 antibodies and long term survival after subsequent ACT. Thus, we hypothesized that treatment with anti-CTLA-4 antibodies can induce favourable changes to be detected in TILs.

RESULTS

Expanded T cells from Ipilimumab treated patients had a higher proportion of cells expressing CD27, intracellular CTLA-4, TIM-3 and LAG-3. In addition, broader and more frequent T cell responses against common tumour antigens were detected in patients treated with Ipilimumab as compared to anti-CTLA-4 naïve patients.

MATERIALS AND METHODS

Expanded TILs were obtained from patients with advanced melanoma who had received Ipilimumab in the previous six months, or had not received any type of anti-CTLA-4 antibody. T cell specificity and expression of phenotypic and exhaustion markers were scrutinized as well as functional properties.

CONCLUSIONS

Ipilimumab may induce tumor-infiltration of T cells of a more naïve phenotype expressing markers related to activation or exhaustion. Additionally, Ipilimumab may increase the frequency of T cells recognizing common tumour associated antigens.

Recent Advances in Targeting CD8 T-Cell Immunity for More Effective Cancer Immunotherapy

Recent advances in cancer treatment have emerged from new immunotherapies targeting T-cell inhibitory receptors, including cytotoxic T-lymphocyte associated antigen (CTLA)-4 and programmed cell death (PD)-1. In this context, anti-CTLA-4 and anti-PD-1 monoclonal antibodies have demonstrated survival benefits in numerous cancers, including melanoma and non-small-cell lung carcinoma. PD-1-expressing CD8⁺ T lymphocytes appear to play a major role in the response to these immune checkpoint inhibitors (ICI). Cytotoxic T lymphocytes (CTL) eliminate malignant cells through recognition by the T-cell receptor (TCR) of specific antigenic peptides presented on the surface of cancer cells by major histocompatibility complex class I/beta-2-microglobulin complexes, and through killing of target cells, mainly by releasing the content of secretory lysosomes containing perforin and granzyme B. T-cell adhesion molecules and, in particular, lymphocyte-function-associated antigen-1 and CD103 integrins, and their cognate ligands, respectively, intercellular adhesion molecule 1 and E-cadherin, on target cells, are involved in strengthening the interaction between CTL and tumor cells. Tumor-specific CTL have been isolated from tumor-infiltrating lymphocytes and peripheral blood lymphocytes (PBL) of patients with varied cancers. TCRβ-chain gene usage indicated that CTL identified in vitro selectively expanded in vivo at the tumor site compared to autologous PBL. Moreover, functional studies indicated that these CTL mediate human leukocyte antigen class I-restricted cytotoxic activity toward autologous tumor cells. Several of them recognize truly tumor-specific antigens encoded by mutated genes, also known as neoantigens, which likely play a key role in antitumor CD8 T-cell immunity. Accordingly, it has been shown that the presence of T lymphocytes directed toward tumor neoantigens is associated with patient response to immunotherapies, including ICI, adoptive cell transfer, and dendritic cell-based vaccines. These tumor-specific mutation-derived antigens open up new perspectives for development of effective second-generation therapeutic cancer vaccines.

T-cell Responses in the Microenvironment of Primary Renal Cell Carcinoma-Implications for Adoptive Cell Therapy

In vitro expansion of large numbers of highly potent tumor-reactive T cells appears a prerequisite for effective adoptive cell therapy (ACT) with autologous tumor-infiltrating lymphocytes (TIL) as shown in metastatic melanoma (MM). We therefore sought to determine whether renal cell carcinomas (RCC) are infiltrated with tumor-reactive T cells that could be efficiently employed for adoptive transfer immunotherapy. TILs and autologous tumor cell lines (TCL) were successfully generated from 22 (92%) and 17 (77%) of 24 consecutive primary RCC specimens and compared with those generated from metastatic melanoma. Immune recognition of autologous TCLs or fresh tumor digests was observed in CD8⁺ TILs from 82% of patients (18/22). Cytotoxicity assays confirmed the tumoricidal capacity of RCC-TILs. The overall expansion capacity of RCC-TILs was similar to MM-TILs. However, the magnitude, polyfunctionality, and ability to expand in classical expansion protocols of CD8⁺ T-cell responses was lower compared with MM-TILs. The RCC-TILs that did react to the tumor were functional, and antigen presentation and processing of RCC tumors was similar to MM-TILs. Direct recognition of tumors with cytokine-induced overexpression of human leukocyte antigen class II was observed from CD4⁺ T cells (6/12; 50%). Thus, TILs from primary RCC specimens could be isolated, expanded, and could recognize tumors. However, immune responses of expanded CD8⁺ RCC-TILs were typically weaker than MM-TILs and displayed a mono-/oligofunctional pattern. The ability to select, enrich, and expand tumor-reactive polyfunctional T cells may be critical in developing effective ACT with TILs for RCC. In summary, TILs isolated from primary RCC specimens could recognize tumors. However, their immune responses were weaker than MM-TILs and displayed a mono-/oligofunctional pattern. The ability to select and expand polyfunctional T cells may improve cell therapy for RCC. Cancer Immunol Res; 6(2); 222-35. ©2018 AACR.

TNFα blockade overcomes resistance to anti-PD-1 in experimental melanoma

Antibodies against programmed cell death-1 (PD-1) have considerably changed the treatment for melanoma. However, many patients do not display therapeutic response or eventually relapse. Moreover, patients treated with anti-PD-1 develop immune-related adverse events that can be cured with anti-tumor necrosis factor α (TNF) antibodies. Whether anti-TNF antibodies affect the anti-cancer immune response remains unknown. Our recent work has highlighted that TNFR1-dependent TNF signalling impairs the accumulation of CD8+ tumor-infiltrating T lymphocytes (CD8+ TILs) in mouse melanoma. Herein, our results indicate that TNF or TNFR1 blockade synergizes with anti-PD-1 on anti-cancer immune responses towards solid cancers. Mechanistically, TNF blockade prevents anti-PD-1-induced TIL cell death as well as PD-L1 and TIM-3 expression. TNF expression positively correlates with expression of PD-L1 and TIM-3 in human melanoma specimens. This study provides a strong rationale to develop a combination therapy based on the use of anti-PD-1 and anti-TNF in cancer patients.

Most melanoma patients do not respond to anti-PD1 therapy. Here, the authors show that TNFα blockade synergizes with anti-PD-1 by preventing anti-PD-1-induced CD8+ T cell death and TIM-3 expression on such cells.

Immunotherapy in managing metastatic melanoma: which treatment when?

INTRODUCTION

Ten to fifteen percent of melanoma patients develop distant or unresectable metastasis requiring systemic treatment. Around 45% of the patients diagnosed with metastatic cutaneous melanoma harbor a BRAFV600 mutation and derive benefit from combined targeted therapy with MAPK pathway inhibitors. These offer a rapid response that translates into improvement of symptoms and increased quality of life. However, resistance often develops with subsequent progressive disease. Immunotherapy with checkpoint inhibitors may be offered to BRAF-mutated and wild-type patients and is associated with longer and durable responses that can continue over years. Areas covered: In this review, the authors discuss the late evidence for targeted and immunotherapy in melanoma patients, as well as therapy sequencing. Immunotherapy in special populations is also addressed. Expert opinion: Effective treatments are currently available. However, there are still unanswered questions of the best therapy sequence, the clear superiority of combined immunotherapy versus monotherapy in all patients, and therapy duration. Since different promising treatments will become available, clinical trials comparing the diverse options in terms of safety, efficacy and cost- effectiveness are required to make the right decisions. Consequently, patients should be encouraged to participate in clinical trials, whenever possible.

Detection of ABCB5 tumour antigen-specific CD8+ T cells in melanoma patients and implications for immunotherapy

ATP binding cassette subfamily B member 5 (ABCB5) has been identified as a tumour-initiating cell marker and is expressed in various malignancies, including melanoma. Moreover, treatment with anti-ABCB5 monoclonal antibodies has been shown to inhibit tumour growth in xenotransplantation models. Therefore, ABCB5 represents a potential target for cancer immunotherapy. However, cellular immune responses against ABCB5 in humans have not been described so far. Here, we investigated whether ABCB5-reactive T cells are present in human melanoma patients and tested the applicability of ABCB5-derived peptides for experimental induction of human T cell responses. Peripheral blood mononuclear cells (PBMNC) isolated from blood samples of melanoma patients (n = 40) were stimulated with ABCB5 peptides, followed by intracellular cytokine staining (ICS) for interferon (IFN)-γ and tumour necrosis factor (TNF)-α. To evaluate immunogenicity of ABCB5 peptides in naive healthy donors, CD8 T cells were co-cultured with ABCB5 antigen-loaded autologous dendritic cells (DC). ABCB5 reactivity in expanded T cells was assessed similarly by ICS. ABCB5-reactive CD8⁺ T cells were detected ex vivo in 19 of 29 patients, melanoma antigen recognised by T cells (MART-1)-reactive CD8⁺ T cells in six of 21 patients. In this small, heterogeneous cohort, reactivity against ABCB5 was significantly higher than against MART-1. It occurred significantly more often and independently of clinical characteristics. Reactivity against ABCB5 could be induced in 14 of 16 healthy donors in vitro by repeated stimulation with peptide-loaded autologous DC. As ABCB5-reactive CD8 T cells can be found in the peripheral blood of melanoma patients and an ABCB5-specific response can be induced in vitro in naive donors, ABCB5 could be a new target for immunotherapies in melanoma.

CD4 and CD8 T lymphocyte interplay in controlling tumor growth

The outstanding clinical success of immune checkpoint blockade has revived the interest in underlying mechanisms of the immune system that are capable of eliminating tumors even in advanced stages. In this scenario, CD4 and CD8 T cell responses are part of the cancer immune cycle and both populations significantly influence the clinical outcome. In general, the immune system has evolved several mechanisms to protect the host against cancer. Each of them has to be undermined or evaded during cancer development to enable tumor outgrowth. In this review, we give an overview of T lymphocyte-driven control of tumor growth and discuss the involved tumor-suppressive mechanisms of the immune system, such as senescence surveillance, cancer immunosurveillance, and cancer immunoediting with respect to recent clinical developments of immunotherapies. The main focus is on the currently existing knowledge about the CD4 and CD8 T lymphocyte interplay that mediates the control of tumor growth.

LAG3 (CD223) as a cancer immunotherapy target

Despite the impressive impact of CTLA4 and PD1-PDL1-targeted cancer immunotherapy, a large proportion of patients with many tumor types fail to respond. Consequently, the focus has shifted to targeting alternative inhibitory receptors (IRs) and suppressive mechanisms within the tumor microenvironment. Lymphocyte activation gene-3 (LAG3) (CD223) is the third IR to be targeted in the clinic, consequently garnering considerable interest and scrutiny. LAG3 upregulation is required to control overt activation and prevent the onset of autoimmunity. However, persistent antigen exposure in the tumor microenvironment results in sustained LAG3 expression, contributing to a state of exhaustion manifest in impaired proliferation and cytokine production. The exact signaling mechanisms downstream of LAG3 and interplay with other IRs remain largely unknown. However, the striking synergy between LAG3 and PD1 observed in multiple settings, coupled with the contrasting intracellular cytoplasmic domain of LAG3 as compared with other IRs, highlights the potential uniqueness of LAG3. There are now four LAG3-targeted therapies in the clinic with many more in preclinical development, emphasizing the broad interest in this IR. Given the translational relevance of LAG3 and the heightened interest in the impact of dual LAG3/PD1 targeting in the clinic, the outcome of these trials could serve as a nexus; significantly increasing or dampening enthusiasm for subsequent targets in the cancer immunotherapeutic pipeline.

PD-1+ Polyfunctional T Cells Dominate the Periphery after Tumor-Infiltrating Lymphocyte Therapy for Cancer

Purpose: Infusion of highly heterogeneous populations of autologous tumor-infiltrating lymphocytes (TIL) can result in tumor regression of exceptional duration. Initial tumor regression has been associated with persistence of tumor-specific TILs 1 month after infusion, but mechanisms leading to long-lived memory responses are currently unknown. Here, we studied the dynamics of bulk tumor-reactive CD8⁺ T-cell populations in patients with metastatic melanoma following treatment with TILs.Experimental Design: We analyzed the function and phenotype of tumor-reactive CD8⁺ T cells contained in serial blood samples of 16 patients treated with TILs.Results: Polyfunctional tumor-reactive CD8⁺ T cells accumulated over time in the peripheral lymphocyte pool. Combinatorial analysis of multiple surface markers (CD57, CD27, CD45RO, PD-1, and LAG-3) showed a unique differentiation pattern of polyfunctional tumor-reactive CD8⁺ T cells, with highly specific PD-1 upregulation early after infusion. The differentiation and functional status appeared largely stable for up to 1 year after infusion. Despite some degree of clonal diversification occurring in vivo within the bulk tumor-reactive CD8⁺ T cells, further analyses showed that CD8⁺ T cells specific for defined tumor antigens had similar differentiation status.Conclusions: We demonstrated that tumor-reactive CD8⁺ T-cell subsets that persist after TIL therapy are mostly polyfunctional, display a stable partially differentiated phenotype, and express high levels of PD-1. These partially differentiated PD-1⁺ polyfunctional TILs have a high capacity for persistence and may be susceptible to PD-L1/PD-L2-mediated inhibition. Clin Cancer Res; 23(19); 5779-88. ©2017 AACR.

Acquired Immune Resistance Follows Complete Tumor Regression without Loss of Target Antigens or IFNγ Signaling

Cancer immunotherapy can result in durable tumor regressions in some patients. However, patients who initially respond often experience tumor progression. Here, we report mechanistic evidence of tumoral immune escape in an exemplary clinical case: a patient with metastatic melanoma who developed disease recurrence following an initial, unequivocal radiologic complete regression after T-cell-based immunotherapy. Functional cytotoxic T-cell responses, including responses to one mutant neoantigen, were amplified effectively with therapy and generated durable immunologic memory. However, these immune responses, including apparently effective surveillance of the tumor mutanome, did not prevent recurrence. Alterations of the MHC class I antigen-processing and presentation machinery (APM) in resistant cancer cells, but not antigen loss or impaired IFNγ signaling, led to impaired recognition by tumor-specific CD8⁺ T cells. Our results suggest that future immunotherapy combinations should take into account targeting cancer cells with intact and impaired MHC class I-related APM. Loss of target antigens or impaired IFNγ signaling does not appear to be mandatory for tumor relapse after a complete radiologic regression. Personalized studies to uncover mechanisms leading to disease recurrence within each individual patient are warranted. Cancer Res; 77(17); 4562-6. ©2017 AACR.

Immune and molecular correlates in melanoma treated with immune checkpoint blockade

Immunotherapy for metastatic melanoma has a decades-long history, and the relatively recent use of checkpoint inhibitors has revolutionized treatment. Durable and sometimes complete remission of metastatic melanoma is now achievable in some patients who receive checkpoint-blocking therapy. However, it is unclear why some patients fare better than others. This review highlights several molecular indicators of response to checkpoint inhibition in metastatic melanoma, focusing on tumor programmed death ligand 1 expression, major histocompatibility complex class I expression, mutational load in the tumor, and T-cell infiltration into the tumor. In addition, clinical correlates of response, notably vitiligo and other immune-related adverse events, can potentially shed light on the mechanisms by which checkpoint blockade may achieve such great success, particularly in melanoma. The authors propose that microphthalmia-associated transcription factor-a key regulator of melanocyte survival, melanin production, and melanoma transformation-produces a molecular landscape in melanocytes and melanoma cells that can make melanomas particularly susceptible to checkpoint blockade and also can result in immune attack on normal melanocytes. Cancer 2017;123:2143-53. © 2017 American Cancer Society.

HBV-specific CD4+ cytotoxic T cells in hepatocellular carcinoma are less cytolytic toward tumor cells and suppress CD8+ T cell-mediated antitumor immunity

In East Asia and sub-Saharan Africa, chronic infection is the main cause of the development of hepatocellular carcinoma, an aggressive cancer with low survival rate. Cytotoxic T cell-based immunotherapy is a promising treatment strategy. Here, we investigated the possibility of using HBV-specific CD4⁺ cytotoxic T cells to eliminate tumor cells. The naturally occurring HBV-specific cytotoxic CD4⁺ and CD8⁺ T cells were identified by HBV peptide pool stimulation. We found that in HBV-induced hepatocellular carcinoma patients, the HBV-specific cytotoxic CD4⁺ T cells and cytotoxic CD8⁺ T cells were present at similar numbers. But compared to the CD8⁺ cytotoxic T cells, the CD4⁺ cytotoxic T cells secreted less cytolytic factors granzyme A (GzmA) and granzyme B (GzmB), and were less effective at eliminating tumor cells. In addition, despite being able to secrete cytolytic factors, CD4⁺ T cells suppressed the cytotoxicity mediated by CD8⁺ T cells, even when CD4⁺ CD25⁺ regulator T cells were absent. Interestingly, we found that interleukin 10 (IL-10)-secreting Tr1 cells were enriched in the cytotoxic CD4⁺ T cells. Neutralization of IL-10 abrogated the suppression of CD8⁺ T cells by CD4⁺ CD25^- T cells. Neither the frequency nor the absolute number of HBV-specific CD4⁺ cytotoxic T cells were correlated with the clinical outcome of advanced stage hepatocellular carcinoma patients. Together, this study demonstrated that in HBV-related hepatocellular carcinoma, CD4⁺ T cell-mediated cytotoxicity was present naturally in the host and had the potential to exert antitumor immunity, but its capacity was limited and was associated with immunoregulatory properties.

The HLA-DR mediated signalling increases the migration and invasion of melanoma cells, the expression and lipid raft recruitment of adhesion receptors, PD-L1 and signal transduction proteins

The constitutive expression of Major Histocompatibility Complex (MHC) class II molecules is restricted to professional Antigen-Presenting Cells (APCs), nevertheless almost 50% of melanomas express constitutively the MHC class II molecules. Therefore, in two MHC class II constitutive expressing melanoma cell lines we studied the signalling mediated by the HLA-DR molecules in the aim to understand the consequence of class II mediated signalling on metastatic dissemination of melanoma. In particular, we reported that the HLA-DR mediated signalling play a new role in melanoma progression, increasing the migration and invasion of melanoma cells. Furthermore, we showed that the HLA-DR mediated signalling increases the expression and the lipid raft localisation of class II molecules, PD-L1 receptor, Integrin and CAM adhesion receptors, FAK, AKT and STAT3 signalling proteins. We also showed that the HLA-DR mediated signalling increases the activation of FAK, AKT, ERK, PKC and STAT3 signalling proteins and the expression of ILK, PAX, BRAF, ERK and PKC. Indeed, the results showed suggest that the HLA-DR mediated signalling provides a platform useful to frustrate an effective anti-tumour response and to increase melanoma migration and metastatic dissemination of this cancer.

Cutaneous squamous cell cancer (cSCC) risk and the human leukocyte antigen (HLA) system

Cutaneous squamous cell carcinoma (cSCC) is the second most common cancer among Caucasians in the United States, with rising incidence over the past decade. Treatment for non-melanoma skin cancer, including cSCC, in the United States was estimated to cost $4.8 billion in 2014. Thus, an understanding of cSCC pathogenesis could have important public health implications. Immune function impacts cSCC risk, given that cSCC incidence rates are substantially higher in patients with compromised immune systems. We report a systematic review of published associations between cSCC risk and the human leukocyte antigen (HLA) system. This review includes studies that analyze germline class I and class II HLA allelic variation as well as HLA cell-surface protein expression levels associated with cSCC risk. We propose biological mechanisms for these HLA-cSCC associations based on known mechanisms of HLA involvement in other diseases. The review suggests that immunity regulates the development of cSCC and that HLA-cSCC associations differ between immunocompetent and immunosuppressed patients. This difference may reflect the presence of viral co-factors that affect tumorigenesis in immunosuppressed patients. Finally, we highlight limitations in the literature on HLA-cSCC associations, and suggest directions for future research aimed at understanding, preventing and treating cSCC.

T-helper cell receptors from long-term survivors after telomerase cancer vaccination for use in adoptive cell therapy

We herein report retargeting of T-helper (Th) cells against the universal cancer antigen telomerase for use in adoptive cell therapy. The redirected Th cells may counter tumor tolerance, transform the inflammatory milieu, and induce epitope spreading and cancer senescence. We have previously conducted a series of trials evaluating vaccination with telomerase peptides. From long-term survivors, we isolated >100 CD4⁺ Th-cell clones recognizing telomerase epitopes. The clones were characterized with regard to HLA restriction, functional avidity, fine specificity, proliferative capacity, cytokine profile, and recognition of naturally processed epitopes. DP4 is the most prevalent HLA molecule worldwide. Two DP4-restricted T-cell clones with different functional avidity, C13 and D71, were selected for molecular T-cell receptor (TCR) cloning. Both clones showed a high proliferative capacity, recognition of naturally processed telomerase epitopes, and a polyfunctional and Th1-weighted cytokine profile. TCR C13 and D71 were cloned into the retroviral vector MP71 together with the compact and GMP-applicable marker/suicide gene RQR8. Both TCRs were expressed well in recipient T cells after PBMC transduction. The transduced T cells co-expressed RQR8 and acquired the desired telomerase specificity, with a polyfunctional response including production of TNFa, IFNγ, and CD107a. Interestingly, the DP4-restricted TCRs were expressed and functional both in CD4⁺ and CD8⁺ T cells. The findings demonstrate that the cloned TCRs confer recipient T cells with the desired hTERT-specificity and functionality. We hypothesize that adoptive therapy with Th cells may offer a powerful novel approach for overcoming tumor tolerance and synergize with other forms of immunotherapy.

CD4+ T cell-mediated cytotoxicity eliminates primary tumor cells in metastatic melanoma through high MHC class II expression and can be enhanced by inhibitory receptor blockade

Metastatic melanoma is a rapidly progressing disease with high mortality rate and limited treatment options. Immunotherapy based on tumor-targeting cytotoxic T cell responses represents a promising strategy. To assist in its development, we examined the possibility and efficacy of using CD4+ cytotoxic T cells. The regulatory mechanisms controlling CD4+ T cell-mediated cytotoxicity were also investigated. We found that naturally occurring granzyme B and perforin-expressing CD4+ cytotoxic T cells can be recovered from metastatic melanoma patients at significantly elevated frequencies compared to those from healthy controls. These CD4+ cytotoxic T cells were also capable of killing autologous tumor cells harvested from metastatic melanoma, independent of CD8+ T cells or any other cell types. However, several restricting factors were observed. First, the cytolytic activity by CD4+ T cells required high MHC class II expression on melanoma cells, which was not satisfied in a subset of melanomas. Second, the granzyme B and perforin release by activated CD4+ cytotoxic T cells was reduced after coculturing with autologous melanoma cells, characterized by low LAMP-1 expression and low granzyme B and perforin secretion in the supernatant. This suggested that inhibitory mechanisms were present to suppress CD4+ cytotoxic T cells. Indeed, blockade of PD-1 and CTLA-4 had increased the cytolytic activity of CD4+ T cells but was only effective in MHC class II high but not MHC class II low melanomas. Together, our study showed that CD4+ T cell-mediated cytotoxicity could eliminate primary melanoma cells but the efficacy depended on MHC class II expression.

Large-scale detection of antigen-specific T cells using peptide-MHC-I multimers labeled with DNA barcodes

Identification of the peptides recognized by individual T cells is important for understanding and treating immune-related diseases. Current cytometry-based approaches are limited to the simultaneous screening of 10-100 distinct T-cell specificities in one sample. Here we use peptide-major histocompatibility complex (MHC) multimers labeled with individual DNA barcodes to screen >1,000 peptide specificities in a single sample, and detect low-frequency CD8 T cells specific for virus- or cancer-restricted antigens. When analyzing T-cell recognition of shared melanoma antigens before and after adoptive cell therapy in melanoma patients, we observe a greater number of melanoma-specific T-cell populations compared with cytometry-based approaches. Furthermore, we detect neoepitope-specific T cells in tumor-infiltrating lymphocytes and peripheral blood from patients with non-small cell lung cancer. Barcode-labeled pMHC multimers enable the combination of functional T-cell analysis with large-scale epitope recognition profiling for the characterization of T-cell recognition in various diseases, including in small clinical samples.

Melanoma Lesions Independently Acquire T-cell Resistance during Metastatic Latency

Melanoma often recurs after a latency period of several years, presenting a T cell-edited phenotype that reflects a role for CD8(+) T cells in maintaining metastatic latency. Here, we report an investigation of a patient with multiple recurrent lesions, where poorly immunogenic melanoma phenotypes were found to evolve in the presence of autologous tumor antigen-specific CD8(+) T cells. Melanoma cells from two of three late recurrent metastases, developing within a 6-year latency period, lacked HLA class I expression. CD8(+) T cell-resistant, HLA class I-negative tumor cells became clinically apparent 1.5 and 6 years into stage IV disease. Genome profiling by SNP arrays revealed that HLA class I loss in both metastases originated from a shared chromosome 15q alteration and independently acquired focal B2M gene deletions. A third HLA class I haplotype-deficient lesion developed in year 3 of stage IV disease that acquired resistance toward dominant CD8(+) T-cell clonotypes targeting stage III tumor cells. At an early stage, melanoma cells showed a dedifferentiated c-Jun(high)/MITF(low) phenotype, possibly associated with immunosuppression, which contrasted with a c-Jun(low)/MITF(high) phenotype of T cell-edited tumor cells derived from late metastases. In summary, our work shows how tumor recurrences after long-term latency evolve toward T-cell resistance by independent genetic events, as a means for immune escape and immunotherapeutic resistance. Cancer Res; 76(15); 4347-58. ©2016 AACR.

Long-Lasting Complete Responses in Patients with Metastatic Melanoma after Adoptive Cell Therapy with Tumor-Infiltrating Lymphocytes and an Attenuated IL2 Regimen

PURPOSE

Adoptive cell transfer therapy (ACT) based on autologous tumor-infiltrating lymphocytes (TIL) has achieved impressive clinical results in several phase I and II trials performed outside of Europe. Although transient, the toxicities associated with high-dose (HD) bolus IL2 classically administered together with TILs are severe. To further scrutinize whether similar results can be achieved with lower doses of IL2, we have carried out a phase I/II trial of TIL transfer after classical lymphodepleting chemotherapy followed by an attenuated IL2 regimen.

EXPERIMENTAL DESIGN

Twenty-five patients with progressive treatment-refractory metastatic melanoma, good clinical performance, age < 70 years, and at least one resectable metastasis were eligible. TIL infusion was preceded by standard lymphodepleting chemotherapy and followed by attenuated doses of IL2 administered in an intravenous, continuous decrescendo regimen (ClinicalTrials.gov Identifier: NCT00937625).

RESULTS

Classical IL2-related toxicities were observed but patients were manageable in a general oncology ward without the need for intervention from the intensive care unit. RECIST 1.0 evaluation displayed three complete responses and seven partial responses (ORR 42%). Median overall survival was 21.8 months. Tumor regression was associated with a higher absolute number of infused tumor-reactive T cells. Moreover, induction and persistence of antimelanoma T-cell responses in the peripheral blood was strongly correlated to clinical response to treatment.

CONCLUSIONS

TIL-ACT with a reduced IL2 decrescendo regimen results in long-lasting complete responses in patients with treatment-refractory melanoma. Larger randomized trials are needed to elucidate whether clinical efficacy is comparable with TIL-ACT followed by HD bolus IL2. Clin Cancer Res; 22(15); 3734-45. ©2016 AACR.

The controversial role of TNF in melanoma

TNF has been associated with both inhibition and promotion of tumor growth. We recently described a mechanism by which tumor cells attract TNF producing cells via expression of MHC class II molecules.