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Summary 4-1BB has been considered a promising target in cancer immunotherapy for decades. Nevertheless, early 4-1BB–targeted agents demonstrated significant liver immuno-toxicity. A new wave of 4-1BB–based therapy is being developed to circumvent hepatotoxicity with a bispecific molecule that directs 4-1BB agonism to the tumor microenvironment by targeting tumor-associated immune checkpoint molecule PD-L1. See related article by Peper-Gabriel et al., p. 3387

It has been reported that a group of patients with advanced non–small cell lung cancer showed circulating T cells with a senescent phenotype, and an abundance of such cells is associated with worse clinical response to immune checkpoint inhibitors. This study encourages further analysis of the role of senescent T cells in resistance to lung cancer immunotherapy. See related article by Ferrara et al., p. 492

In the original version of [this article][1] ([1][2]), author Miguel F. Sanmamed's name was spelled incorrectly. The error has been corrected in the latest online HTML and PDF versions of the article. The authors regret this error. 1. 1.[↵][3]1. Sun J, 2. Lu Q, 3. Sanmamed MF

Purpose: To determine the expression level, associations, and biological role of PD-L1, IDO-1, and B7-H4 in non–small cell lung cancer (NSCLC). Experimental Design: Using multiplexed quantitative immunofluorescence (QIF), we measured the levels of PD-L1, IDO-1, B7-H4, and different tumor-infiltrating lymphoycte (TIL) subsets in 552 stages I–IV lung carcinomas from two independent populations. Associations between the marker levels, TILs, and major clinicopathologic variables were determined. Validation of findings was performed using mRNA expression data from The Cancer Genome Atlas (TCGA) and in vitro stimulation of lung adenocarcinoma A549 cells with IFNγ and IL10. Results: PD-L1 was detected in 16.9% and 21.8% of cases in each population. IDO-1 was expressed in 42.6% and 49.8%; and B7-H4 in 12.8% and 22.6% of cases, respectively. Elevated PD-L1 and IDO-1 were consistently associated with prominent B- and T-cell infiltrates, but B7-H4 was not. Coexpression of the three protein markers was infrequent, and comparable results were seen in the lung cancer TCGA dataset. Levels of PD-L1 and IDO-1 (but not B7-H4) were increased by IFNγ stimulation in A549 cells. Treatment with IL10 upregulated B7-H4 but did not affect PD-L1 and IDO-1 levels. Conclusions: PD-L1, IDO-1, and B7-H4 are differentially expressed in human lung carcinomas and show limited co-expression. While PD-L1 and IDO-1 are associated with increased TILs and IFNγ stimulation, B7-H4 is not. The preferential expression of discrete immune evasion pathways in lung cancer could participate in therapeutic resistance and support design of optimal clinical trials. Clin Cancer Res; 23(2); 370–8. ©2016 AACR.

Purpose: Myeloid-derived suppressor cells (MDSC) are considered an important T-cell immunosuppressive component in cancer-bearing hosts. The factors that attract these cells to the tumor microenvironment are poorly understood. IL8 (CXCL8) is a potent chemotactic factor for neutrophils and monocytes. Experimental Design: MDSC were characterized and sorted by multicolor flow cytometry on ficoll-gradient isolated blood leucokytes from healthy volunteers (n = 10) and advanced cancer patients (n = 28). In chemotaxis assays, sorted granulocytic and monocytic MDSC were tested in response to recombinant IL8, IL8 derived from cancer cell lines, and patient sera. Neutrophil extracellular traps (NETs) formation was assessed by confocal microscopy, fluorimetry, and time-lapse fluorescence confocal microscopy on short-term MDSC cultures. Results: IL8 chemoattracts both granulocytic (GrMDSC) and monocytic (MoMDSC) human MDSC. Monocytic but not granulocytic MDSC exerted a suppressor activity on the proliferation of autologous T cells isolated from the circulation of cancer patients. IL8 did not modify the T-cell suppressor activity of human MDSC. However, IL8 induced the formation of NETs in the GrMDSC subset. Conclusions: IL8 derived from tumors contributes to the chemotactic recruitment of MDSC and to their functional control. Clin Cancer Res; 22(15); 3924–36. ©2016 AACR.

Purpose: Interleukin-8 (IL8) is a chemokine produced by malignant cells of multiple cancer types. It exerts various functions in shaping protumoral vascularization and inflammation/immunity. We evaluated sequential levels of serum IL8 in preclinical tumor models and in patients to assess its ability to estimate tumor burden. Experimental Design: IL8 levelsweremonitored by sandwich ELISAs incultured tumor cells supernatants, tumor-xenograftedmice serum, and in samples from126 patients with cancer. Wecorrelated IL8 serumlevels with baseline tumor burden and with treatment-induced changes in tumor burden, as well as with prognosis. Results: IL8 concentrations correlated with the number of IL8-producing tumor cells in culture. In xenografted neoplasms, IL8 serum levels rapidly dropped after surgical excision, indicating an accurate correlation with tumor burden. In patients with melanoma (n = 16), renal cell carcinoma (RCC; n = 23), non-small cell lung cancer (NSCLC; n = 21), or hepatocellular carcinoma (HCC; n = 30), serum IL8 concentrations correlated with tumor burden and stage, survival (melanoma, n = 16; RCC, n = 23; HCC, n = 33), and objective responses to therapy, including those to BRAF inhibitors (melanoma, n = 16) and immunomodulatory monoclonal antibodies (melanoma, n = 8). IL8 concentrations in urine (n = 18) were mainly elevated in tumors with direct contact with the urinary tract. Conclusions: IL8 levels correlate with tumor burden in preclinical models and in patients with cancer. IL8 is a potentially useful biomarker to monitor changes in tumor burden following anticancer therapy, and has prognostic significance. Fil: Sanmamed, Miguel F.. Universidad de Navarra; España Fil: Carranza Rua, Omar. Universidad de Navarra; España Fil: Alfaro, Carlos. Universidad de Navarra; España Fil: Oñate, Carmen. Universidad de Navarra; España Fil: Martín Algarra, Salvador. Universidad de Navarra; España Fil: Perez, Guiomar. Universidad de Navarra; España Fil: Landazuri, Sara F.. Universidad de Navarra; España Fil: Gonzalez, Alvaro. Universidad de Navarra; España Fil: Gross, Stefanie. University Hospital Erlangen; Alemania Fil: Rodriguez, Inmaculada. Universidad de Navarra; España Fil: Muñoz Calleja, Cecilia. Universidad Autonoma de Madrid. Hospital Universitario de la Princesa; España Fil: Rodríguez Ruiz, María. Universidad de Navarra; España Fil: Sangro, Bruno. Universidad de Navarra; España Fil: López Picazo, José M.. Universidad de Navarra; España Fil: Rizzo, Manglio Miguel. Universidad Austral. Facultad de Ciencias Biomédicas. Laboratorio de Terapia Genética; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mazzolini Rizzo, Guillermo Daniel. Universidad Austral. Facultad de Ciencias Biomédicas. Laboratorio de Terapia Genética; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pascual, Juan I.. Universidad de Navarra; España Fil: Andueza, Maria Pilar. Universidad de Navarra; España Fil: Perez Gracia, Jose Luis. Universidad de Navarra; España Fil: Melero, Ignacio. Universidad de Navarra; España

Therapy for cancer can be achieved by artificially stimulating antitumor T and natural killer (NK) lymphocytes with agonist monoclonal antibodies (mAb). T and NK cells express several members of the TNF receptor (TNFR) family specialized in delivering a costimulatory signal on their surface. Engagement of these receptors is typically associated with proliferation, elevated effector functions, resistance to apoptosis, and differentiation into memory cells. These receptors lack any intrinsic enzymatic activity and their signal transduction relies on associations with TNFR-associated factor (TRAF) adaptor proteins. Stimulation of CD137 (4-1BB), CD134 (OX40), and glucocorticoid-induced TNFR (GITR; CD357) promotes impressive tumor-rejecting immunity in a variety of murine tumor models. The mechanisms of action depend on a complex interplay of CTL, T-helper cells, regulatory T cells, dendritic cells, and vascular endothelium in tumors. Agonist mAbs specific for CD137 have shown signs of objective clinical activity in patients with metastatic melanoma, whereas anti-OX40 and anti-GITR mAbs have entered clinical trials. Preclinical evidence suggests that engaging TNFR members would be particularly active with conventional cancer therapies and additional immunotherapeutic approaches. Indeed, T-cell responses elicited to tumor antigens by means of immunogenic tumor cell death are amplified by these immunostimulatory agonist mAbs. Furthermore, anti-CD137 mAbs have been shown to enhance NK-mediated cytotoxicity elicited by rituximab and trastuzumab. Combinations with other immunomodulatory mAb that block T-cell checkpoint blockade receptors such as CTLA-4 and PD-1 are also promising. Clin Cancer Res; 19(5); 1044–53. ©2013 AACR.

Type I interferons (IFN-I) are well-known inducers of tumor cell apoptosis and antiangiogenesis via signaling through a common receptor interferon alpha receptor (IFNAR). IFNAR induces the Janus activated kinase–signal transducer and activation of transcription (JAK-STAT) pathway in most cells, along with other biochemical pathways that may differentially operate, depending on the responding cell subset, and jointly control a large collection of genes. IFNs-I were found to systemically activate natural killer (NK) cell activity. Recently, mouse experiments have shown that IFNs-I directly activate other cells of the immune system, such as antigen-presenting dendritic cells (DC) and CD4 and CD8 T cells. Signaling through the IFNAR in T cells is critical for the acquisition of effector functions. Cross-talk between IFNAR and the pathways turned on by other surface lymphocyte receptors has been described. Importantly, IFNs-I also increase antigen presentation of the tumor cells to be recognized by T lymphocytes. These IFN-driven immunostimulatory pathways offer opportunities to devise combinatorial immunotherapy strategies. Clin Cancer Res; 17(9); 2619–27. ©2011 AACR.

PDX models are limited by the absence of a complete and functional immune system. Overwhelming evidence now exists to suggest that immune cells play an integral role in the development and maintenance of tumors. Without a functional immune system, PDX models cannot reflect the dynamic processes of tumor-immune surveillance and immune-mediated editing, limiting the translation of antitumor results obtained in these models. Another important consequence of lacking an immune system is the impossibility to test in these models anticancer drugs that directly target immune cells. To overcome these important limitations, PDX models with human immune systems are needed. There are different approaches to enrich PDX models with human immune cells: engrafting human peripheral blood mononuclear cells, engrafting hematopoietic stem cells, or engrafting primary patient-derived tumor xenografts with human tumor infiltrating lymphocytes. All these alternatives have different strengths and weaknesses that are important to know for obtaining preclinical results that are meaningful for clinical translation. Citation Format: Miguel F. Sanmamed. Innovative PDX models for studying immunotherapy of cancer. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr IA28.