Uncoupling CD4+ TIL-Mediated Tumor Killing from JAK-Signaling in Melanoma.

PURPOSE: Impaired MHCI-presentation and insensitivity to immune effector molecules are common features of immune checkpoint blockade (ICB)-resistant tumors and can be, respectively, associated with loss of ß2 microglobulin (B2M) or impaired IFNγ signaling. Patients with ICB-resistant tumors can respond to alternative immunotherapies, such as infusion of autologous tumor-infiltrating lymphocytes (TIL). CD4+ T cells can exert cytotoxic functions against tumor cells; however, it is unclear whether CD4+ T-cell responses can be exploited to improve the clinical outcomes of patients affected by ICB-resistant tumors. EXPERIMENTAL DESIGN: Here, we exploited CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 gene editing to reproduce immune-resistant tumor phenotypes via gene knockout (KO). To determine the role of cytotoxic CD4+ TILs in ICB-resistant tumors, we investigated CD4+ TIL-mediated cytotoxicity in matched pairs of TILs and autologous melanoma cell lines, used as a model of patient-specific immune-tumor interaction. Around 40% of melanomas constitutively express MHC Class II molecules; hence, melanomas with or without natural constitutive MHC Class II expression (MHCIIconst+ or MHCIIconst-) were used. RESULTS: CD4+ TIL-mediated cytotoxicity was not affected by B2M loss but was dependent on the expression of CIITA. MHCIIconst+ melanomas were killed by tumor-specific CD4+ TILs even in the absence of IFNγ-mediated MHCII upregulation, whereas IFNγ was necessary for CD4+ TIL-mediated cytotoxicity against MHCIIconst- melanomas. Notably, although tumor-specific CD4+ TILs did not kill JAK1KO MHCIIconst- melanomas even after IFNγ stimulation, sensitivity to CD4+ TIL-mediated cytotoxicity was maintained by JAK1KO MHCIIconst+ melanomas. CONCLUSIONS: In conclusion, our data indicate that exploiting tumor-specific cytotoxic CD4+ TILs could help overcome resistance to ICB mediated by IFNγ-signaling loss in MHCIIconst+ melanomas. See related commentary by Betof Warner and Luke, p. 3829.

Coexisting Alterations of MHC Class I Antigen Presentation and IFNγ Signaling Mediate Acquired Resistance of Melanoma to Post-PD-1 Immunotherapy.

Responses to immunotherapy can be very durable but acquired resistance leading to tumor progression often occurs. We investigated a patient with melanoma resistant to anti-programmed death 1 (anti-PD-1) who participated in the CA224-020 clinical trial (NCT01968109) and had further progression after an initial objective response to anti-PD-1 plus anti-lymphocyte activation gene 3. We found consecutive acquisition of beta-2 microglobulin (B2M) loss and impaired Janus kinase 1 (JAK1) signaling that coexisted in progressing tumor cells. Functional analyses revealed a pan T-cell immune escape phenotype, where distinct alterations mediated independent immune resistance to tumor killing by autologous CD8+ tumor-infiltrating lymphocytes (TIL; B2M loss) and CD4+ TILs (impaired JAK1 signaling). These findings shed light on the complexity of acquired resistance to immunotherapy in the post anti-PD-1 setting, indicating that coexisting altered pathways can lead to pan T-cell immune escape.

Tumor-infiltrating lymphocytes for adoptive cell therapy: recent advances, challenges, and future directions.

INTRODUCTION: Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TILs) is a highly personalized type of cancer immunotherapy. TIL-based ACT exploits naturally occurring TILs, derived from the patients' tumor. This treatment has shown consistent clinical responses in melanoma, and recent results point toward a potential use in multiple cancer diagnoses. However, several limitations have restricted the clinical development and adaptation of TIL-based ACT. AREAS COVERED: In this review, we present the principles of TIL-based ACT and discuss the most significant limitations for therapeutic efficacy and its widespread application. The topics of therapeutic resistance (both innate and acquired), treatment-related toxicity, and the novel research topic of metabolic barriers in the tumor microenvironment (TME) are covered. EXPERT OPINION: There are many ongoing areas of research focusing on improving clinical efficacy and optimizing TIL-based ACT. Many strategies have shown a great potential, particularly strategies advancing TIL efficacy (such as increasing and harnessing ex vivo the sub-population of tumor-reactive TILs) and manufacturing processes. Novel approaches can help overcome current limitations and potentially result in TIL-based ACT entering the mainstream of cancer therapy across tumor types.

Rapid Identification of the Tumor-Specific Reactive TIL Repertoire via Combined Detection of CD137, TNF, and IFNγ, Following Recognition of Autologous Tumor-Antigens.

Detecting the entire repertoire of tumor-specific reactive tumor-infiltrating lymphocytes (TILs) is essential for investigating their immunological functions in the tumor microenvironment. Current in vitro assays identifying tumor-specific functional activation measure the upregulation of surface molecules, de novo production of antitumor cytokines, or mobilization of cytotoxic granules following recognition of tumor-antigens, yet there is no widely adopted standard method. Here we established an enhanced, yet simple, method for identifying simultaneously CD8+ and CD4+ tumor-specific reactive TILs in vitro, using a combination of widely known and available flow cytometry assays. By combining the detection of intracellular CD137 and de novo production of TNF and IFNγ after recognition of naturally-presented tumor antigens, we demonstrate that a larger fraction of tumor-specific and reactive CD8+ TILs can be detected in vitro compared to commonly used assays. This assay revealed multiple polyfunctionality-based clusters of both CD4+ and CD8+ tumor-specific reactive TILs. In situ, the combined detection of TNFRSF9, TNF, and IFNG identified most of the tumor-specific reactive TIL repertoire. In conclusion, we describe a straightforward method for efficient identification of the tumor-specific reactive TIL repertoire in vitro, which can be rapidly adopted in most cancer immunology laboratories.

The effects of targeted immune-regulatory strategies on tumor-specific T-cell responses in vitro.

BACKGROUND: Immune-related adverse events (IrAEs) are auto-immune reactions associated with immune checkpoint inhibitor-based therapy (ICI). Steroids are currently the first-line option for irAE management; however, recent studies have raised concerns regarding their potential impairment of tumor-specific immune responses. In this study, we investigated the in vitro effects of commonly used irAE treatment drugs on the anti-tumor activity of tumor-infiltrating lymphocytes (TILs). METHODS: Impairment of anti-tumor immune responses by four drugs (antibodies: vedolizumab and tocilizumab; small molecules: mycophenolate mofetil and tacrolimus) reported to be effective in treating irAEs was tested at clinically relevant doses in vitro and compared to a standard moderate dose of corticosteroids (small molecules) or infliximab (antibodies). TIL responses against autologous tumor cell lines, in the presence or absence of irAE drugs, were determined by flow cytometry (short-term tumor-specific T-cell activation) or xCELLigence (T-cell-mediated tumor killing). RESULTS: None of the tested antibodies influenced T-cell activation or T-cell-mediated tumor killing. Low-dose mycophenolate and tacrolimus did not influence T-cell activation, whereas higher doses of tacrolimus (> 1 ng/ml) impaired T-cell activation comparably to dexamethasone. All tested small molecules impaired T-cell-mediated tumor killing, with high-dose tacrolimus reducing killing at levels comparable to dexamethasone-mediated inhibition. In addition, mycophenolate and tacrolimus alone also demonstrated anti-proliferative effects on tumor cells. CONCLUSIONS: These data support clinical testing of targeted immune-regulatory strategies in the initial phase of irAE management, as a potential replacement for corticosteroids.

Qualitative Analysis of Tumor-Infiltrating Lymphocytes across Human Tumor Types Reveals a Higher Proportion of Bystander CD8+ T Cells in Non-Melanoma Cancers Compared to Melanoma.

Background: Human intratumoral T cell infiltrates can be defined by quantitative or qualitative features, such as their ability to recognize autologous tumor antigens. In this study, we reproduced the tumor-T cell interactions of individual patients to determine and compared the qualitative characteristics of intratumoral T cell infiltrates across multiple tumor types. Methods: We employed 187 pairs of unselected tumor-infiltrating lymphocytes (TILs) and autologous tumor cells from patients with melanoma, renal-, ovarian-cancer or sarcoma, and single-cell RNA sequencing data from a pooled cohort of 93 patients with melanoma or epithelial cancers. Measures of TIL quality including the proportion of tumor-reactive CD8+ and CD4+ TILs, and TIL response polyfunctionality were determined. Results: Tumor-specific CD8+ and CD4+ TIL responses were detected in over half of the patients in vitro, and greater CD8+ TIL responses were observed in melanoma, regardless of previous anti-PD-1 treatment, compared to renal cancer, ovarian cancer and sarcoma. The proportion of tumor-reactive CD4+ TILs was on average lower and the differences less pronounced across tumor types. Overall, the proportion of tumor-reactive TILs in vitro was remarkably low, implying a high fraction of TILs to be bystanders, and highly variable within the same tumor type. In situ analyses, based on eight single-cell RNA-sequencing datasets encompassing melanoma and five epithelial cancers types, corroborated the results obtained in vitro. Strikingly, no strong correlation between the proportion of CD8+ and CD4+ tumor-reactive TILs was detected, suggesting the accumulation of these responses in the tumor microenvironment to follow non-overlapping biological pathways. Additionally, no strong correlation between TIL responses and tumor mutational burden (TMB) in melanoma was observed, indicating that TMB was not a major driving force of response. No substantial differences in polyfunctionality across tumor types were observed. Conclusions: These analyses shed light on the functional features defining the quality of TIL infiltrates in cancer. A significant proportion of TILs across tumor types, especially non-melanoma, are bystander T cells. These results highlight the need to develop strategies focused on the tumor-reactive TIL subpopulation.

Modulation of Tetraspanin 32 (TSPAN32) Expression in T Cell-Mediated Immune Responses and in Multiple Sclerosis.

Tetraspanins are a conserved family of proteins involved in a number of biological processes including, cell-cell interactions, fertility, cancer metastasis and immune responses. It has previously been shown that TSPAN32 knockout mice have normal hemopoiesis and B-cell responses, but hyperproliferative T cells. Here, we show that TSPAN32 is expressed at higher levels in the lymphoid lineage as compared to myeloid cells. In vitro activation of T helper cells via anti-CD3/CD28 is associated with a significant downregulation of TSPAN32. Interestingly, engagement of CD3 is sufficient to modulate TSPAN32 expression, and its effect is potentiated by costimulation with anti-CD28, but not anti-CTLA4, -ICOS nor -PD1. Accordingly, we measured the transcriptomic levels of TSPAN32 in polarized T cells under Th1 and Th2 conditions and TSPAN32 resulted significantly reduced as compared with unstimulated cells. On the other hand, in Treg cells, TSPAN32 underwent minor changes upon activation. The in vitro data were finally translated into the context of multiple sclerosis (MS). Encephalitogenic T cells from Myelin Oligodendrocyte Glycoprotein (MOG)-Induced Experimental Autoimmune Encephalomyelitis (EAE) mice showed significantly lower levels of TSPAN32 and increased levels of CD9, CD53, CD82 and CD151. Similarly, in vitro-activated circulating CD4 T cells from MS patients showed lower levels of TSPAN32 as compared with cells from healthy donors. Overall, these data suggest an immunoregulatory role for TSPAN32 in T helper immune response and may represent a target of future immunoregulatory therapies for T cell-mediated autoimmune diseases.

Prediction of PD-L1 Expression in Neuroblastoma via Computational Modeling.

Immunotherapy is a promising new therapeutic approach for neuroblastoma (NBM): an anti-GD2 vaccine combined with orally administered soluble beta-glucan is undergoing a phase II clinical trial and nivolumab and ipilimumab are being tested in recurrent and refractory tumors. Unfortunately, predictive biomarkers of response to immunotherapy are currently not available for NBM patients. The aim of this study was to create a computational network model simulating the different intracellular pathways involved in NBM, in order to predict how the tumor phenotype may be influenced to increase the sensitivity to anti-programmed cell death-ligand-1 (PD-L1)/programmed cell death-1 (PD-1) immunotherapy. The model runs on COPASI software. In order to determine the influence of intracellular signaling pathways on the expression of PD-L1 in NBM, we first developed an integrated network of protein kinase cascades. Michaelis-Menten kinetics were associated to each reaction in order to tailor the different enzymes kinetics, creating a system of ordinary differential equations (ODEs). The data of this study offers a first tool to be considered in the therapeutic management of the NBM patient undergoing immunotherapeutic treatment.

Overexpression of macrophage migration inhibitory factor and functionally-related genes, D-DT, CD74, CD44, CXCR2 and CXCR4, in glioblastoma.

The macrophage migration inhibition factor (MIF) is a cytokine with multiple biological functions, including the cancer-associated processes, cell cycle deregulation, angiogenesis and metastatization. The present study investigated the expression of MIF and its functionally associated genes (D-DT, CD74, CD44, CXCR2 and CXCR4) in glioblastoma multiforme (GBM). The data were obtained from The Cancer Genome Atlas databank, through the cBioportal web-based utility (cbioportal.org/). A significant increase was observed in the majority of these genes in GBM samples compared with lower grade gliomas, however no significant correlation among the selected genes and the overall survival of the patients was identified. In contrast, the expression of MIF exhibited a trend toward an increase in overall survival and a significant increase of MIF expression was observed in samples of patients who underwent neoadjuvant treatment. In conclusion these data indicate that MIF and its receptors are involved in GBM progression and maintenance. Deciphering the precise biological significance in GBM would favor the adoption of tailored approaches to modulate the function of MIF and its associated genes for the treatment of the disease.