Antitumor Immunity In Mouse Model Research Articles

Abstract 5301: Tumor-targeted activation of CD137 using Bicycles: New insights into mechanism of action and discovery of BT7455, a clinical candidate for the treatment of EphA2-expressing cancers

Abstract Introduction: Clinical studies in cancer patients have validated CD137 agonism as an activator of the immune system to enable tumor rejection. We have demonstrated that small, chemically synthetic bicyclic peptides can drive tumor-localized agonism of CD137 and anti-tumor immunity in mouse models. Here, we report the next stage of our work - delving into the mechanism of action of these novel agents and extending our program to serve patients whose tumors express EphA2. Experimental Procedures: MultiOmyx™ hyperplexed immunofluorescence assay was used to evaluate the expression of CD137 and EphA2 in head and neck squamous cell carcinoma samples. Human PBMC/tumor cell co-culture assays were used to assess CD137 Bicycle TICA™ in vitro bioactivity and syngeneic mouse tumor models were used to evaluate CD137 Bicycle TICA anti-tumor activity as mono- or combination therapies. Pharmacodynamic activity was evaluated by transcriptional profiling using NanoString assays or single cell RNA sequencing. Summary of the Data: Studies utilizing a syngeneic mouse model and deep RNA sequencing of tumors from CD137 Bicycle TICA-treated mice implicated intratumoral dendritic cells in addition to T cells as early responders to localized CD137 agonism and potential contributors to the anti-tumor response. Furthermore, a mouse efficacy model demonstrated synergy with checkpoint inhibitor therapy. Multiplex imaging revealed that EphA2 and CD137 are co-expressed in human tumors of high unmet medical need and therefore, using our highly modular Bicycle platform, we discovered BT7455, a Bicycle TICA that engages EphA2 and CD137 with high affinity, resulting in potent EphA2-dependent activity in vitro and robust anti-tumor activity in vivo with intermittent dosing in mouse models. Gene expression profiling of tumors revealed that BT7455 led to increased production of cytokines and chemokines known to drive T cell infiltration, the extent of which differentiated it from both a checkpoint inhibitor and an anti-CD137 monoclonal antibody agonist. BT7455 was well tolerated in preclinical species and liver function tests indicated no evidence of hepatic toxicity. Statement of Conclusions: In summary, we have identified EphA2 as a promising target to pair with a CD137 agonist. In addition to CD8+ T cells, tumor-resident dendritic cells are a likely contributor to anti-tumor immunity following treatment with Bicycle® TICAs, supporting utility for Bicycle® tumor-targeted CD137 agonists in solid tumors beyond those that are highly T cell-infiltrated. We have advanced a clinical development candidate, BT7455, to realize this potential for patients with EphA2-expressing cancers. Citation Format: Johanna Lahdenranta, Kristen Hurov, Heather Cohen, Lia Luus, Cara Bray, Peter Brown, Anna Devlen, Carly Campbell, Matthew Gray, Mike Kelly, Gemma Mudd, Punit Upadhyaya, Sailaja Battula, Kelvin Zhang, Anne-Sophie Dugast, Kevin McDonnell, Phil Brandish, Nicholas Keen. Tumor-targeted activation of CD137 using Bicycles: New insights into mechanism of action and discovery of BT7455, a clinical candidate for the treatment of EphA2-expressing cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5301.

Hybrid LNP Prime Dendritic Cells for Nucleotide Delivery.

The efficient activation of professional antigen-presenting cells-such as dendritic cells (DC)-in tumors and lymph nodes is critical for the design of next-generation cancer vaccines and may be able to provide anti-tumor effects by itself through immune stimulation. The challenge is to stimulate these cells without causing excessive toxicity. It is hypothesized that a multi-pronged combinatorial approach to DC stimulation would allow dose reductions of innate immune receptor-stimulating TLR3 agonists while enhancing drug efficacy. Here, a hybrid lipid nanoparticle (LNP) platform is developed and tested for double-stranded RNA (polyinosinic:polycytidylic acid for TLR3 agonism) and immune modulator (L-CANDI) delivery. This study shows that the ≈120nm hybrid nanoparticles-in-nanoparticles effectively eradicate tumors by themselves and generate long-lasting, durable anti-tumor immunity in mouse models.

Abstract 5964: Context-dependent induction of interferon signaling by CD11b agonists supports anti-tumor immunity in mouse models and human cancer patients

Abstract Chronic activation of inflammatory pathways and suppressed interferon signaling are hallmarks of myeloid cells in immunosuppressive tumors that drive poor responsiveness to conventional and immune therapies. Previous studies have identified agonistic activation of the CD11b integrin as a potential strategy to enhance anti-tumor immunity. However, the mechanisms by which CD11b-agonism reprogram tumor immunity are poorly understood, and this may impair patient selection and identification of effective treatment combinations. Here we will use a combination of in vitro systems, animal models, and samples from first in human clinical trials of the CD11b-agonist to identify the mechanism of action of this approach and identify combinations for further testing. CD11b agonism alters tumor-associated macrophage (TAM) phenotypes by simultaneously repressing NFκB/IL1-signaling and activating interferon (IFN) gene expression. Repression of NFκB/IL-1 signaling was due to rapid degradation of p65 protein by the proteosome, contributing to suppressing myeloid cells infiltration. In contrast, CD11b agonism triggers mitochondrial dysfunction to stimulate STING-induced, STAT1-mediated interferon signaling, contributing to macrophages-augmented anti-tumor T cell immunity. Tissues from phase I clinical trials shows that CD11b agonist activates STING and STAT1 signaling in TAMs in human tumors, which is in consistent with preclinical data. Furthermore, combining CD11b agonism with cytotoxic therapies, STING agonist or TLRs agonists leads to robust anti-tumor activity in PDAC models. These studies pave the way for mechanism-based therapeutic combination strategies in cancer patients. Citation Format: Xiuting Liu, Graham Hogg, Chong Zuo, John Baer, Varintra Lander, Liang Kang, Nicholas Borcherding, Brett Knolhoff, Robin Osterhout, Anna Galkin, Jean Bruey, Laura Carter, Cedric Mpoy, Julie Schwarz, Haeseong Park, Vineet Gupta, David DeNardo. Context-dependent induction of interferon signaling by CD11b agonists supports anti-tumor immunity in mouse models and human cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5964.

An anti-mesothelin targeting antibody drug conjugate induces pyroptosis and ignites antitumor immunity in mouse models of cancer

BackgroundEmerging evidence suggests that the mechanism of chemotherapy-induced cell death may influence the antitumor immune response in patients with cancer. Unlike immunologically silent apoptosis, pyroptosis is a lytic and inflammatory...

Increased CD73 expression is associated with poorly differentiated Gleason score and tumor size in prostate cancer

There are few prostate cancer prognostic biomarkers. However, clinical difficulties in distinguishing between aggressive and non-aggressive tumors have been observed. CD73 is a 70-kDa glycosylphosphatidylinositol (GPI)-linked ecto-enzyme that reduces antitumor immunity in mouse models of tumor, particularly prostate cancer. It's believed to be a promising biomarker for predicting the clinical development and prognosis of certain tumor types. Its function in prostate cancer, however, is unknown. This study aims to investigate the hypothesis that CD73 may be used as a biomarker in prostate cancer diagnosis and/or prognosis. Nuclear and cytoplasmic CD73 staining has been evaluated by immunohistochemistry using benign (23) and malignant (75) prostate tissues. The immunohistochemical study showed nuclear and cytoplasmic CD73 staining in cancerous and non-cancerous prostate tissues. Increased CD73 staining was shown in prostate cancer tissues compared to benign prostate tissues. A negative association between CD73 expression and Gleason scores has been observed. However, increased cytoplasmic CD73 staining was significantly associated with increasing tumor size. This finding suggests that CD73 may have a role in cancer development or aggressiveness, indicating that more research is needed to better understand its function and determine whether it might be used as a diagnostic biomarker for prostate cancer.

Removing the B (cell) STING to improve cancer immunotherapy.

Removing the B (cell) STING to improve cancer immunotherapy.

Macrophage-Targeting by CSF1/1R Blockade in Pancreatic Cancers.

Published in Cancer Research in 2014, Zhu and colleagues achieved a mechanistic leap in our understanding of cancer-associated macrophage biology with their proof-of-concept study showing that macrophage-specific targeting, via blocking colony-stimulating factor-1 (CSF1) signaling through its cognate receptor CSF1R, synergized with checkpoint immunotherapy to enhance antitumor immunity in mouse models of pancreatic cancer. Here, we reflect on the critical set of observations presented in this study and how the study's findings fueled the subsequent efforts to translate CSF1/1R-specific and other tumor-associated macrophage modulating therapies into the clinic.See related article by Zhu and colleagues, Cancer Res 2014;74:5057-69.

Targeted epigenetic induction of mitochondrial biogenesis enhances antitumor immunity in mouse model

Considering the potential of combinatorial therapies in overcoming existing limitations of cancer immunotherapy, there is an increasing need to identify small-molecule modulators of immune cells capable of augmenting the effect of programmed cell death protein 1 (PD-1) blockade, leading to better cancer treatment. Although epigenetic drugs showed potential in combination therapy, the lack of sequence specificity is a major concern. Here, we identify and develop a DNA-based epigenetic activator with tri-arginine vector called EnPGC-1 that can trigger the targeted induction of the peroxisome proliferator-activated receptor-gamma coactivator 1 alpha/beta (PGC-1α/β), a regulator of mitochondrial biogenesis. EnPGC-1 enhances mitochondrial activation, energy metabolism, proliferation of CD8+ Tcells invitro, and, in particular, enhances oxidative phosphorylation, a feature of long-lived memory Tcells. Genome-wide gene analysis suggests that EnPGC-1 and not the control compounds can regulate Tcell activation as a major biological process. EnPGC-1 also synergizes with PD-1 blockade to enhance antitumor immunity and improved host survival.

Abstract 1788: Increasing the therapeutic index of IL12 by engineering for tumor specific protease activation

Abstract IL-12 is a cytokine produced by antigen-presenting cells that increases T cell proliferation, IFN gamma mediated Th1 effector functions and T and NK cell cytotoxicity. While these effects generate potent anti-tumor immunity in mouse models, the high toxicity of IL-12 in cancer patients has limited its clinical utility. Potency attenuation and intratumoral cytokine localization may improve IL-12 tolerability, but these approaches can reduce efficacy or be limited by intratumoral delivery or tumor antigen expression. To improve both tolerability and efficacy of IL-12, we engineered IL-12Fc fusions with anti-IL-12 antibodies to block IL-12 potency. Using linkers designed to be cleaved by highly active intratumoral proteases, blocking antibodies are released specifically in the tumor microenvironment, thereby increasing intratumoral IL-12 activity. Single chain IL-12 was fused to one C-termini of an Azymetric™ Fc heterodimer. To the other Fc C-termini, an anti-IL-12 scFv was fused via a protease-cleavable linker in order to block IL-12 activity. In addition to antibody blockade, modifications of IL-12Fc fusions were used to further limit IL-12Fc activity. In vitro potency was determined by CD8T cell IFN gamma release. Anti-IL-12 scFv cleavage in the presence of recombinant enzyme or human tumor material was assessed by reducing CE-SDS and LC/MS, respectively. All IL-12Fc fusions were produced with favorable biophysical characteristics. Modified IL-12Fc molecules had up to 500x reduced potency, while antibody blocked IL-12Fc molecules had up to 100,000x reduced potency compared to IL-12Fc control. In vitro cleavage of the anti-IL-12 scFv from IL-12Fc recovered potency to that of the corresponding non-masked IL-12Fc molecules. Reducing CE-SDS confirmed that anti-IL-12 scFvs were cleaved from IL-12Fc in the presence of recombinant enzyme. Cleavage of anti-IL-12 scFvs also occurred when variants were incubated in pancreatic tumor cell supernatant or human tumor tissue lysate. These results indicate that antibody blockade and re-activation by protease cleavage is a promising strategy to localize the activity of IL-12 to the tumor microenvironment while potentially limiting off-tumor toxicities. Further modifying antibody blocked IL-12 has the potential to better fine tune therapeutic index. We are pursuing tumor-specific IL-12 fusions for clinical application in tumors with high intratumoral protease activity. Citation Format: Jennifer Leah Bishop, Ryan Blackler, Gesa Volkers, Maya Poffenberger, Irene Yu, Joel Smith, Akram Khodabandehloo, Sifa Arrafi, Desmond Lau, Liz Stangle, Leisa Stenberg, Patricia Zwierzchowski, Iulia Dude, David Douda, Grant Wickman, Jeff Proctor, Gerry Rowse, Laurence Madera, Genevieve Desjardins, Nicole Afacan, Stuart Barnscher, David Mills, Thomas Spreter, Surjit Dixit. Increasing the therapeutic index of IL12 by engineering for tumor specific protease activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1788.

Reprogramming lipid metabolism prevents effector T cell senescence and enhances tumor immunotherapy.

The functional state of T cells is a key determinant for effective antitumor immunity and immunotherapy. Cellular metabolism, including lipid metabolism, controls T cell differentiation, survival, and effector functions. Here, we report that development of T cell senescence driven by both malignant tumor cells and regulatory T cells is a general feature in cancers. Senescent T cells have active glucose metabolism but exhibit unbalanced lipid metabolism. This unbalanced lipid metabolism results in changes of expression of lipid metabolic enzymes, which, in turn, alters lipid species and accumulation of lipid droplets in T cells. Tumor cells and Treg cells drove elevated expression of group IVA phospholipase A2, which, in turn, was responsible for the altered lipid metabolism and senescence induction observed in T cells. Mitogen-activated protein kinase signaling and signal transducer and activator of transcription signaling coordinately control lipid metabolism and group IVA phospholipase A2 activity in responder T cells during T cell senescence. Inhibition of group IVA phospholipase A2 reprogrammed effector T cell lipid metabolism, prevented T cell senescence in vitro, and enhanced antitumor immunity and immunotherapy efficacy in mouse models of melanoma and breast cancer in vivo. Together, these findings identify mechanistic links between T cell senescence and regulation of lipid metabolism in the tumor microenvironment and provide a new target for tumor immunotherapy.

Intratumoral IL12 mRNA Therapy Promotes TH1 Transformation of the Tumor Microenvironment.

While immune checkpoint inhibitors such as anti-PD-L1 are rapidly becoming the standard of care in the treatment of many cancers, only a subset of treated patients have long-term responses. IL12 promotes antitumor immunity in mouse models; however, systemic recombinant IL12 had significant toxicity and limited efficacy in early clinical trials. We therefore designed a novel intratumoral IL12 mRNA therapy to promote local IL12 tumor production while mitigating systemic effects. A single intratumoral dose of mouse (m)IL12 mRNA induced IFNγ and CD8+ T-cell-dependent tumor regression in multiple syngeneic mouse models, and animals with a complete response demonstrated immunity to rechallenge. Antitumor activity of mIL12 mRNA did not require NK and NKT cells. mIL12 mRNA antitumor activity correlated with TH1 tumor microenvironment (TME) transformation. In a PD-L1 blockade monotherapy-resistant model, antitumor immunity induced by mIL12 mRNA was enhanced by anti-PD-L1. mIL12 mRNA also drove regression of uninjected distal lesions, and anti-PD-L1 potentiated this response. Importantly, intratumoral delivery of mRNA encoding membrane-tethered mIL12 also drove rejection of uninjected lesions with very limited circulating IL12p70, supporting the hypothesis that local IL12 could induce a systemic antitumor immune response against distal lesions. Furthermore, in ex vivo patient tumor slice cultures, human IL12 mRNA (MEDI1191) induced dose-dependent IL12 production, downstream IFNγ expression and TH1 gene expression. These data demonstrate the potential for intratumorally delivered IL12 mRNA to promote TH1 TME transformation and robust antitumor immunity.See related commentary by Cirella et al., p. 6080.

Alternative Checkpoints as Targets for Immunotherapy.

Purpose of ReviewImmunotherapy has shown an unprecedented response in treatment of tumors. However, challenges such as lack of cytotoxic lymphocytes to mount an immune response or development of resistance to therapy can limit efficacy. Here, we discuss alternative checkpoints that can be targeted to improve cytotoxic lymphocyte function while harnessing other components of the immune system.Recent FindingsBlockade of alternative checkpoints has improved anti-tumor immunity in mouse models and is being tested clinically with encouraging findings. In addition to modulating T cell function directly, alternative checkpoints can also regulate activity of myeloid cells and regulatory T cells to affect anti-tumor response.SummaryCombination of immune checkpoint inhibitors can improve treatment of tumors by activating multiple arms of the immune system.

Targeted Epigenetic Induction of Mitochondrial Biogenesis Enhances Antitumor Immunity in Mouse Model

Here, we prepared a library of pyrrole–imidazole polyamides, PIPs encompassing the P300/CBP-selective bromodomain inhibitor (BI), which acts as a P300/CBP recruiter, and identified a PIP called BI-PIP-R that can trigger the targeted induction of the peroxisome proliferator-activated receptor-gamma coactivator 1 alpha/beta (PGC-1 α/β), a regulator of mitochondrial activation and biogenesis. We further improved the chemical architecture of this PIP using a tri-arginine vector to generate a designer dual-functional molecule termed EnPGC-1 that enhanced mitochondrial activation, energy metabolism, proliferation of CD8+ T cells in vitro, and, in particular, enhanced oxidative phosphorylation (OXPHOS), a feature of long-lived memory T cells. Collectively, the ability of EnPGC-1 to synergize with PD-1 checkpoint blockade represents the first example of a programmable DNA-based epigenetic drug with the potential to overcome the existing issues in cancer immunotherapy.

CD19-targeting fusion protein combined with PD1 antibody enhances anti-tumor immunity in mouse models

ABSTRACT In our previous studies, using a B cell vaccine (scFv-Her2), the targeting of tumor-associated antigen Her2 (human epidermal growth factor receptor-2) to B cells via the anti-CD19 single chain variable fragment (scFv) was shown to augment tumor-specific immunity, which enhanced tumor control in the prophylactic and therapeutic setting. However, the fusion protein displayed limited activity against established tumors, and local relapses often occurred following scFv-Her2 treatment, indicating that scFv-Her2-induced responses are inadequate to maintain anti-tumor immunity. In this study, targeting the IV region (D4) of the extracellular region of Her2 to B cells via CD19 molecules (scFv-Her2D4) was found to enhance IFN-γ-producing-CD8+ T cell infiltration in tumor tissues and reduced the number of tumor-infiltrating myeloid-derived suppressor cells (MDSCs). However, negative co-stimulatory molecules such as programmed cell death protein-1 (PD-1), CD160, and LAG-3 on T cells and programmed death protein ligand-1 (PD-L1) on tumor cells were upregulated in the tumor microenvironment after scFv-Her2D4 treatment. Further, anti-PD1 administration enhanced the efficacy of scFv-Her2D4 and anti-tumor immunity, as evidenced by the reversal of tumor-infiltrating CD8+ T cell exhaustion and the reduction of MDSCs and Treg cells, which suppress T cells and alter the tumor immune microenvironment. Moreover, combining this with anti-PD1 antibodies promoted complete tumor rejection. Our data provide evidence of a close interaction among tumor vaccines, T cells, and the PD-L1/PD-1 axis and establish a basis for the rational design of combination therapy with immune modulators and tumor vaccine therapy.

Literature Highlights: Impactful Papers Published Elsewhere

Engineering safer immunolocks and keys (by Wapcaplet via Wikimedia Commons)IL2 therapy is used with caution due to adverse events at IL2 concentrations that are clinically useful. A modified IL2 receptor, which only binds to a modified form of IL2, was inserted into T cells destined for adoptive antitumor therapy. The modified IL2 was designed to only bind the modified receptor, and, as administration of this modified IL2 activates only the transferred T cells, the IL2 provides not only therapeutic benefit but also is not associated with identifiable toxicity.Sockolosky JT, …, Garcia KC. Science 2018 Mar 2;359:1037–42.Fibroblast engulfing debris (From Lakins et al.)Tumor fibroblasts were found to engulf and process tumor cell debris, then cross-present it to T cells. However, instead of activating T cells, this presentation is suppressive and reduces T-cell viability. The T-cell death results from increased expression of FasL and PD-L2 on the fibroblasts that, in turn, activates Fas and PD-1 pathways in the T cells. Blockade of these interactions restored antigen-specific T-cell killing of tumor cells.Lakins MA, …, Shields JD. Nat Commun 2018 Mar 5. DOI: 10.1038/s41467-018-03347-0.Tumor-associated macrophage clusters (from Perry et al., Fig. 2)Immunotherapeutics are hampered by suppressive elements in the tumor microenvironment, including M2 (suppressive) macrophages. Perry et al., using an authochthonous mouse model (mutant Braf/Pten) of melanoma, and Hoves et al., primarily with the MC38 model, show that activating CD40 while inhibiting CSF-1R signaling changes transcriptional modules, reduces M2s, increases inflammatory macrophages, and improves tumor control. The effects are strong, but not permanent, and both CD8+ T cells and macrophages are necessary for tumor eradication.Perry CJ, …, Kaech SM. J Exp Med 2018 Feb 7;215:877–93.Hoves S, …, Ries CH. J Exp Med 2018 Feb 7;215:859–76.Fc affinity affects checkpoint blockade effectiveness (from Arce Vargas et al.)Optimization of the interaction between human FcγRs and anti– CTLA-4 in humanized mice expressing human FcγRs efficiently depletes Tregs and controls tumor growth. However, removal of Tregs is only important in tumors that are highly inflamed and infiltrated by CD8+ T cells. Patients carrying FcγR polymorphisms with higher binding affinities for IgGs, and that have higher neoantigen burdens, show greater responses to CTLA-4 blockade.Arce Vargas F, …, Quezada SA. Cancer Cell 2018 Mar 22. DOI: 10.1016/j.ccell.2018.02.010.4-1BB–activated mitochondria (from Teijeira et al., Fig. 6)Removing checks on T-cell activation is often insufficient for reactivating CD8+ T cells. Inducing 4-1BB signaling while blocking PD-1 (Menk et al.) or during adoptive T-cell therapy (Teijeira et al.) induces robust antitumor immunity in mouse models of melanoma or colon cancer. 4-1BB appears to regulate mitochondrial mass and function, reprogramming the metabolic state of antitumor T cells to counter exhaustion.Menk AV, …, Delgoffe GM. J Exp Med 2018 Mar 6. DOI: 10.1084/jem.20171068.Teijeira A, …, Melero I. Cancer Immunol Res 2018 Apr. DOI: 10.1158/2326-6066.CIR-17-0767.Core of hydrogel (by Edgar181 via Wikimedia Commons)Surgery removes primary tumors, but the wound healing process produces an immunosuppressive environment that may be conducive to regrowth of residual tumor cells and distal metastasis. Placing a hydrogel laced with agonists for innate immune responses into post-surgical wounds from which tumors had been extracted resulted in activation of innate and specific antitumor responses and a decrease in metastasis.Park CG, …, Goldberg MS. Sci Transl Med 2018 Mar 21;10:eaar1916.

1178 Post-diagnosis aspirin use and overall survival in patients with melanoma

Melanoma is the fifth most common cancer in the US in 2017 and advanced melanoma is still a deadly disease. We recently showed that platelets promote melanoma growth by suppressing T cell anti-tumor immunity in mouse models. Moreover, tumor-derived prostaglandins and platelets aid in melanoma immune evasion and metastasis in preclinical studies. Therefore, aspirin could have a protective role in melanoma. This is a retrospective cohort study of 1,522 Caucasian patients at an academic center, diagnosed with melanoma between 2000 and 2014 and followed up through 2016. Aspirin use was associated with longer overall survival in univariate analysis and after controlling for age, sex, stage, and treatment modalities (HR 0.58, 95% CI [0.45-0.75]). The association persisted after adjusting for cardiovascular comorbidities/risk factors. While aspirin use was not associated with survival in patients with in situ and stage I melanoma, it was associated with longer survival in stages II (HR 0.45, 95% CI [0.24-0.82]) and III (HR 0.57, 95% CI [0.34-0.96]). A similar trend was observed in a smaller number of stage IV patients (n=112), without reaching statistical significance (HR 0.55, 95% CI [0.27-1.13]). In turn, patients using aspirin before diagnosis were less likely to be diagnosed in stages III (13.1% versus 20.4%) and IV (2.4% versus 8.6%) disease. Moreover, higher platelet count at diagnosis was a poor prognostic indicator: patients in the highest tertile experienced shorter overall survival (HR 1.66, 95% CI [1.13-2.43]). Lastly, in a mouse model of thrombocytopenia, low platelet counts resulted in protection from melanoma dissemination to the lungs. Therefore, aspirin could provide survival advantage in advanced melanoma and clinical trials are warranted.

CD73 Expression Is an Independent Prognostic Factor in Prostate Cancer.

CD73 is an adenosine-generating ecto-enzyme that suppresses antitumor immunity in mouse models of cancer, including prostate cancer. Although high levels of CD73 are associated with poor prognosis in various types of cancer, the clinical impact of CD73 in prostate cancer remains unclear. We evaluated the prognostic value of CD73 protein expression and CD8(+) cell density in 285 cases of prostate cancer on tissue microarray (TMA). Normal adjacent and tumor tissues were evaluated in duplicates. Univariate and multivariate analyses revealed that high levels of CD73 in normal adjacent prostate epithelium were significantly associated with shorter biochemical recurrence (BCR)-free survival. Notably, CD73 expression in normal epithelium conferred a negative prognostic value to prostate-infiltrating CD8(+) cells. Surprisingly, high levels of CD73 in the tumor stroma were associated with longer BCR-free survival in univariate analysis. In vitro studies revealed that adenosine signaling inhibited NF-κB activity in human prostate cancer cells via A2B adenosine receptors. Consistent with these results, CD73 expression in the prostate tumor stroma negatively correlated with p65 expression in the nuclei of prostate tumor cells. Our study revealed that CD73 is an independent prognostic factor in prostate cancer. Our data support a model in which CD73 expression in the prostate epithelium suppresses immunosurveillance by CD8(+) T cells, whereas CD73 expression in the tumor stroma reduces NF-κB signaling in tumor cells via A2B adenosine receptor signaling. CD73 expression, including in normal adjacent prostate epithelium, can thus effectively discriminate between aggressive and indolent forms of prostate cancer.