Jiang, Wen G.

Abstract Glioblastoma is the most common primary tumor of the CNS in adults, representing approximately 50% of all gliomas and 15% of primary brain tumors. The current standard of care for GBM is safe maximal surgical resection followed by radiotherapy and concurrent Temozolomide (TMZ), but median survival continues to be 15–16 months. Temozolomide is a second-generation DNA alkylating agent that induces thymine mispairing during DNA replication resulting in tumor cell G2/M phase arrest and autophagy, a standard care of therapy against GBM. While the success of TMZ in clinical trials showed great promise for its overall efficacy, emerging TMZ resistance make us to think more for the combination therapy. CD47, a tumor cell surface marker, plays as “don't eat me signal” through binding its receptor SIRPα on macrophages and the antibody against CD47, which blocks interactions of CD47 with SIRPα, has been shown to lead to tumor destruction. Furthermore, CD47 is a prognostic marker as its expression predisposes cancer patients to a poorer survival outcome. This has significant clinical implications since approximately more than 80% of patients with the most GBMs, overexpress CD47. Overexpression of CD47 is also associated with a decreased probability of survival in clinical cohorts of GBM. Our work and that of others demonstrate that CD47 blockade enables tumor cell phagocytosis by antigen presenting cells (APC), establishing this molecule as a viable therapeutic target in GBM. We additionally investigated the combinatorial effect of CD47 blockade with temozolomide. DNA alkylating agents induce sporadic tumor cell necrosis associated with the extracellular release of damage associated molecular patterns (DAMPs) such as calreticulin, a pro-phagocytic protein whose interaction with low density lipoprotein receptor-related protein 1 (LRP1) facilitates recognition by professional antigen-presenting cells (APCs) and acts as a critical molecular component in promoting immunogenic cell. Our results showed that tumor cell treatment with temozolomide induces plasma membrane expression of calreticulin. Combination therapy resulted in amplified tumor cell phagocytosis and antigen presentation by APC. In addition, preclinical assessment of combination therapy in a syngeneic murine model of GBM resulted in significantly improved survival, characterized by increased intra-tumor penetration of APC cells. These results suggest that the combination of CD47 blockade with temozolomide may enhance tumor immunogenicity, and can improve clinical outcomes demonstrated by mono-therapeutic approaches with conventional chemotherapy. Citation Format: Yaqing Qie, Christina Von Roemeling, Yuanxin Chen, Kevin Shih, Xiujie Liu, Wen Jiang, Joshua Knight, Charles Chan, Irving Weissman, Betty Kim. CD47 blockade with temozolomide can enhance the therapy in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-208. doi:10.1158/1538-7445.AM2017-LB-208

Abstract While growing evidence suggests that tumor microenvironment can modulate stemness and the mesenchymal phenotype, little is known about how these cell states are coordinately regulated. We report that S100A4 controls both stemness and mesenchymal transition in GBM cells. In a spontaneous mouse glioma model and in primary human GBM tumorspheres, S100A4 expression is enriched in tumor-initiating cells and is required for self-renewal and tumor growth in vivo. In addition, greater than 80 percent of S100A4+ cells are associated with the tumor vasculature, a known niche for glioma stem cells, and S100A4 promotes pro-angiogenic factor expression. Interestingly, acidosis induces expression of S100A4 and the EMT regulators SNAIL1/2 and acidosis-induced EMT regulator expression requires S100A4 function. Importantly, S100A4 functions as a molecular switch between the proneural and mesenchymal states in GBM as S100A4 knockdown results in down-regulation of the mesenchymal signature genes, including the “master transcriptional regulators of mesenchymal transition”, and concurrent up-regulation of proneural signature genes. Together, these results indicate that S100A4 sits in a critical node in the molecular network that controls both glioma stem cells and the mesenchymal phenotype. Citation Format: Kin-Hoe Chow, Hee Jung Park, Joshy George, Yuanxin Chen, Andrew Gallup, Wen Jiang, Betty Y. Kim, Kyuson Yun. Regulation of GBM stemness and mesenchymal transition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4783. doi:10.1158/1538-7445.AM2017-4783

Abstract Solid cancer microenvironment is heterogeneous in nature, comprised of many stromal cell types that work in concert with malignant tumor cells for its maintenance and growth. Among these cell types, tumor-associated macrophages (TAMs) represent a dominant cell population with immunosuppressive and proangiogenic properties. Present in most human cancers, histologic evidence of increased TAMs is often associated with poorer prognosis. Here, we show that the immunosuppressive properties of TAMs can be overcome by modulating tumor microenvironmental parameters. By restoring tumor vascular network and tissue perfusion via anti-vascular endothelial growth factor receptor 2 (VEGFR2) antibody, significant reduction of tumor tissue hypoxia and acidosis can be accomplished. Alteration of these local environmental factors directly results in the polarization of TAMs from an immune inhibitory (M2-like) towards immune stimulatory (M1-like) phenotype. In addition, the restoration of aberrant and dysfunctional tumor vessels leads to changes in local cytokine and protein expression profiles that favor the recruitment of immune effector cells, including increased CXCL9 expression. As a result, both CD4+ helper and CD8+ cytotoxic T cell populations were significantly increased within the tumor. Based on these findings, we tested the utility of combining the optimal dose of anti-VEGFR2 antibody therapy with B7-H4 blockade in breast cancer models. Our preliminary data suggests that such treatment enhanced TAM polarization to an anti-tumor phenotype, increased tumor immune cell infiltration and decreased T-cell inhibition, resulting in synergized anti-cancer effects. Therefore, these results suggest that tumor microenvironment modulating therapy provides a new and interesting strategy to augment active immunotherapy for breast as well as other cancer types. Citation Format: Yuhui Huang, Wen Jiang, Betty Y.S. Kim. Tumor microenvironment modulation enhances macrophage polarization and T-cell activation resulting in synergized anti-cancer effect. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3666. doi:10.1158/1538-7445.AM2014-3666