The growth of a xenograft breast cancer tumor model with engineered hyaluronan-accumulating stroma is dependent on hyaluronan and independent of CD44

Hyaluronan accumulation in the tumor microenvironment is associated with poor prognosis in several solid human cancers. To understand the role of stromal hyaluronan in tumor progression, we engineered 3T3HAS3, a hyaluronan-producing fibroblast cell line, by lentiviral transduction of Balb/c 3T3 cells with the human hyaluronan synthase 3(HAS3) gene. 3T3HAS3 cells significantly enhanced tumor growth when co-grafted with MDA-MB-468 cells in nude mice. Immunohistochemical analysis of the xenograft tumors showed that MDA-MB-468 cells were surrounded by hyaluronan-accumulating stroma, closely resembling the morphology observed in human breast cancer specimens. Tumor growth of MDA-MB-468 + 3T3HAS3 co-grafts was greatly reduced upon hyaluronan degradation by lentiviral transduction of a human hyaluronidase gene in 3T3HAS3 cells, or by systemic administration of pegvorhyaluronidase alfa (PEGPH20). In contrast, the growth of the co-graft tumors was not inhibited when CD44 expression was reduced or ablated by small hairpin RNA-mediated CD44 knockdown in MDA-MB-468 cells, CD44 CRISPR knockout in 3T3HAS3 cells, or by grafting these cells in CD44 knockout nude mice. Collectively, these data demonstrate that tumor growth of an engineered xenograft breast cancer model with hyaluronan-accumulating stroma can be dependent on hyaluronan and independent of CD44.

Abstract 2206: Degradation of hyaluronan in the tumor microenvironment enhances oncolytic reovirus and anti-PD-L1 therapy in a murine syngeneic breast tumor model

The extracellular matrix (ECM) structure heavily influences tumor growth, invasion and various steps of the cancer-immunity cycle. Hyaluronan (HA), a major component of ECM, is a glycosaminoglycan that accumulates in the tumor microenvironment (TME) of many solid tumor types, and HA accumulation can restrict T cell infiltration and promote immunosuppression. We have demonstrated in preclinical tumor models that enzymatic degradation of TME HA by intravenous PEGylated recombinant human hyaluronidase PH20 (Pegvorhyaluronidase alfa, PEGPH20) facilitates delivery of chemotherapeutics to tumors and enhances efficacy of current immunotherapy strategies including checkpoint inhibitors. In this study, we hypothesized that degradation of HA with PEGPH20 treatment may remodel the TME to improve the efficacy of oncolytic reovirus therapy (pelareorep) and checkpoint blockade therapy. To test this hypothesis, EMT6 murine breast tumor cells, which spontaneously accumulate HA and are sensitive to oncolytic activity of pelareorep were implanted orthotopically into the mammary fat pad of BALB/c mice. In this model, PEGPH20 treatment resulted in a reduction of HA measured by immunohistochemistry and induced tumor growth inhibition (30% TGI). Pelareorep plus anti-PD-L1 treatment also resulted in anti-tumor activity (44% TGI), and flow cytometric analysis of tumor infiltrating immune cells in pelareorep + anti-PD-L1-treated tumors demonstrated a significant increase in the numbers of cytotoxic CD8+ tumor infiltrating lymphocytes (TILs, p=0.0004), a decrease in regulatory T cells (T reg, p<0.0001) and an increase in CD8:Treg ratio (p=0.0018), indicating a robust antitumor immune response. Combination of PEGPH20 with pelareorep + anti-PD-L1 resulted in enhanced anti-tumor activity (71% TGI) compared to either PEGPH20 (30%TGI) or pelareorep + anti-PD-L1 (44% TGI). PEGPH20 in combination with pelareorep + anti-PDL1 also extended survival (median survival time, MST- 30 days, p<0.0001) in comparison with PEGPH20 alone (MST-21 days) or pelareorep + anti-PD-L1 (MST-22 days). Our data demonstrate the potential for matrix modeling through degradation of HA as a strategy to improve oncolytic reovirus + anti-PD-L1 immunotherapy. These findings are consistent with prior preclinical studies and support clinical evaluation of combining PEGPH20 with immune checkpoint inhibitors in HA-accumulating tumors.

Citation Format: Jisook Lee, Grey A. Wilkinson, Trevor Kimbler, Barbara Blouw, Curtis B. Thompson. Degradation of hyaluronan in the tumor microenvironment enhances oncolytic reovirus and anti-PD-L1 therapy in a murine syngeneic breast tumor model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2206.

Abstract 1747: Hyaluronan (HA) accumulation restricts CD8+ T cell numbers and skews tumor-associated macrophage (TAM) phenotype in mouse syngeneic pancreatic tumors

The glycosaminoglycan hyaluronan (HA) is abundant in the tumor microenvironment (TME) of diverse solid tumor types, and tumor accumulation of HA is associated with poor patient outcome. We previously demonstrated, in multiple HA-rich mouse syngeneic tumor models, that enzymatic degradation of HA using PEGylated recombinant human hyaluronidase PH20 (pegvorhyaluronidase alfa; PEGPH20) enhanced tumor growth inhibition and increased tumor accumulation of T and NK cells when combined with a checkpoint inhibitor. However, the ability of HA accumulation in the TME to alter the composition of tumor-infiltrating immune cells has not been well characterized. Here, we addressed this question by performing a detailed immune phenotypic analysis of HA-poor and HA-rich tumors using a mouse syngeneic pancreatic tumor model. To achieve this, we transduced Pan02 cells with a lentivirus encoding hyaluronan synthase 3 (HAS3, Pan02-HAS3) or empty vector (EV, Pan02-EV). After peritibial implantation, Pan02-HAS3 tumors contained 13.4-fold higher levels of HA than Pan02-EV tumors, as determined by HA ELISA. Both variants grew with similar kinetics to the Pan02 parental line. Flow cytometric analysis of tumor-infiltrating immune cells in four independent and identical studies revealed an average 6.2-fold reduction in the number of CD8+ T cells in Pan02-HAS3 tumors compared with Pan02-EV. Likewise, numbers of CD4+ T cells and NK cells were reduced by an average of 4.8- and 2.9-fold, respectively, in Pan02-HAS3 tumors compared with Pan02-EV. In contrast, we did not observe consistent differences in the numbers of tumor-associated macrophages (TAMs), neutrophils/granulocytic myeloid-derived suppressor cells (G-MDSC), monocytes/monocytic (M)-MDSC, or dendritic cells (DCs) between the two tumor variants. However, within the TAM population, cells displaying an “M2-like” phenotype (CD206high MHCIIlow) were present at an average 10.5-fold higher frequency in Pan02-HAS3 tumors compared with Pan02-EV. Similarly, the percentage of DCs that were CD103+ CD11b- was reduced by 1.4-fold in Pan02-HAS3 tumors compared with Pan02-EV. Together, our data indicate that HAS3-driven HA accumulation in Pan02 mouse syngeneic tumors induces several aspects of immunosuppression: it restricts the numbers of tumor-infiltrating lymphocytes, and skews TAMs and DCs toward immunosuppressive phenotypes. These findings are consistent with our previous work, which demonstrated that combining PEGPH20 with anti-PD-L1 increased tumor-infiltrating lymphocyte numbers and reduced the frequency of CD206high MHCIIlow TAMs in Pan02-HAS3 tumors. Our results support the ongoing clinical evaluation of PEGPH20 in combination with immunotherapy in HA-rich tumor indications (NCT02563548 and NCT03193190).

Citation Format: Benjamin Thompson, Trevor Kimbler, Jisook Lee, Chunmei Zhao, Kelly Chen, Renee Clift, Curtis B. Thompson, Sanna Rosengren, Daniel C. Maneval. Hyaluronan (HA) accumulation restricts CD8+ T cell numbers and skews tumor-associated macrophage (TAM) phenotype in mouse syngeneic pancreatic tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1747.

Abstract 2101: The growth of a xenograft breast cancer tumor model with engineered hyaluronan-accumulating stroma is dependent on hyaluronan and independent of CD44

The abnormal accumulation of hyaluronan in the solid tumor microenvironment is associated with poor prognosis in several human cancers. Hyaluronan often accumulates in the tumor stroma. To understand the role of hyaluronan-accumulating stroma in tumor progression, we engineered a hyaluronan-producing fibroblast cell line 3T3HAS3 by lentiviral transduction of the human hyaluronan synthase 3 gene into Balb/c 3T3 cells. The 3T3HAS3 cells produced significant amounts of hyaluronan in vitro, which bind to the cell surface of the human breast cancer cell line MDA-MB-468. When co-grafted with MDA-MB-468 cells in nude mice, 3T3HAS3 significantly enhanced tumor growth. Immunohistochemical analysis of tumor xenografts showed that MDA-MB-468 cells were surrounded by hyaluronan-accumulating stroma, closely resembling the morphology observed in human breast cancer specimens. Tumor growth of this co-graft model required hyaluronan production from 3T3HAS3 cells, as demonstrated by the delayed tumor growth upon hyaluronan removal by expression of the human PH20 gene in 3T3HAS3 cells, or by systemic administration of PEGylated recombinant human PH20 (PEGPH20). In contrast, neither the expression of CD44, a well-characterized hyaluronan receptor, in tumor and stromal fibroblasts, nor the binding of hyaluronan to CD44 in MDA-MB-468 tumor cells was essential for tumor growth. Small scale screening of signaling changes in xenograft tumors suggested that the AMPK/mTOR pathway may respond to hyaluronan removal by PEGPH20. Collectively, these data demonstrate that the growth of an engineered breast cancer xenograft model with hyaluronan-accumulating stroma is dependent on hyaluronan, and that hyaluronan-CD44 interaction may not be the main mechanism through which hyaluronan promotes tumor progression in certain tumors.

Citation Format: Chunmei Zhao, Benjamin J. Thompson, Kelly Chen, Mathieu Marella, Susan Zimmerman, Trevor Kimbler, Barbara Blouw, Sheryl Garrovillo, Lei Huang, Adrian Radi, Zhongdong Huang, H. Michael Shepard, Sanna Rosengren, Christopher D. Thanos, Daniel C. Maneval. The growth of a xenograft breast cancer tumor model with engineered hyaluronan-accumulating stroma is dependent on hyaluronan and independent of CD44 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2101.

CRAC channel inhibitors block cytokine production with a pattern distinguishable from cyclosporine (P5216)

Engagement of the T cell receptor (TCR) triggers complex signaling cascades that result in various effector T cell responses. A critical component of TCR signaling is store-operated calcium entry (SOCE) that occurs through the activation of calcium release-activated calcium (CRAC) channels. Activated CRAC channels cause an increase in cytoplasmic calcium, which results in the transcription of calcineurin/NFAT-dependent genes involved in T cell proliferation and cytokine production. Both CRAC channel inhibitors and calcineurin inhibitors are known to inhibit T cell function. However, the relative impact of CRAC channel inhibitors and calcineurin inhibitors on Th1, Th2, Th17, and Treg functions are not known. Using anti-CD3/anti-CD28 to stimulate cytokine production by peripheral blood mononuclear cells (PBMCs), we demonstrate that novel CalciMedica CRAC channel inhibitors have a pattern of cytokine inhibition that is different from the calcineurin inhibitor cyclosporine (CsA). CRAC channel inhibitors inhibit Th1 and Th17 cytokines (IFNγ and IL-17) more potently than Treg and Th2 cytokines (IL-10 and IL-4), while CsA inhibits IL-10 more potently than IFNγ, IL-4, and IL-17. These results suggest that CRAC channel inhibitors and CsA have different potencies against different effector T cell subsets, and that CRAC channel inhibitors may achieve a more favorable balance of effects on pro- versus anti-inflammatory pathways in immune disorders.

Abstract A81: Hyaluronan-dependent skewing of tumor-associated macrophage (TAM) phenotype in a murine pancreatic tumor model is associated with increased tumor hypoxia

Hyaluronan (HA) is a naturally occurring glycosaminoglycan that accumulates in the tumor microenvironment of several cancer types, including pancreatic ductal adenocarcinoma (PDA), where it is an independent negative predictor of survival. An ongoing phase 3 study is evaluating pegvorhyaluronidase alfa (PEGPH20; PVHA), a first-in-class biologic that enzymatically degrades HA in the tumor microenvironment, in combination with gemcitabine and nab-paclitaxel in metastatic PDA. Recently, we reported that HA-accumulation can promote tumor hypoxia; however, the effects this may have on tumor-infiltrating immune cells are unknown. Transduction of syngeneic murine PDA cells (Pan02) with hyaluronan synthase 3 (HAS3) generates tumors (Pan02-HAS3) containing high levels of HA, and a higher frequency of TAMs with an immunosuppressive phenotype (CD206-high MHCII-low), relative to tumors generated by empty vector-transduced cells (Pan02-EV). Given the association of this TAM phenotype with tumor hypoxia, we assessed the relationship between tumor hypoxia and the TAM phenotypes of Pan02-HAS3 and Pan02-EV tumors. To confirm whether the effects seen in Pan02-HAS3 tumors require HA synthesis, we also generated tumors expressing an enzymatically inactive HAS3 mutant (Pan02-HAS3 D215A). Tumor-bearing mice were injected with pimonidazole hydrochloride 2 hours prior to harvest and dissociation of tumor tissue; subsequent flow cytometric analysis of tumor-infiltrating immune cells included an antibody against pimonidazole hydrochloride adducts (HP-1) to detect cells residing in hypoxic zones. A greater mean percentage of TAMs isolated from Pan02-HAS3 peritibial tumors had high levels of HP-1 staining (HP-1+) compared with TAMs isolated from either Pan02-EV or Pan02-HAS3 D215A tumors (18.2%, 4.2% and 3.9%, respectively). Furthermore, HP-1+ cells were enriched among CD206-high MHCII-low TAMs compared with their MHCII-high counterparts in Pan02-HAS3 tumors (38.7% vs 11.9%). Likewise, more HP-1+ cells were seen among dendritic cells (DCs) isolated from Pan02-HAS3 tumors compared with either Pan02-EV or Pan02-HAS3 D215A tumors (6.9%, 1.3% and 0.8%, respectively). Similar findings were obtained in orthotopic tumors. In contrast, no consistent differences in the percentages of HP-1+ CD8 T cells or NK cells were observed across the three tumor types in this study. Finally, exposure of cultured macrophages to hypoxia recapitulated some of the changes in gene expression observed in TAMs sorted from Pan02-HAS3 tumors, including increased expression of Arg1 and Nos2. These data suggest that tumor HA accumulation may promote an immunosuppressive TAM phenotype by creating tumor hypoxic zones that are subsequently infiltrated by TAMs, but not T or NK cells.

Citation Format: Trevor Kimbler, Jessica Cowell, Jisook Lee, Benjamin J. Thompson. Hyaluronan-dependent skewing of tumor-associated macrophage (TAM) phenotype in a murine pancreatic tumor model is associated with increased tumor hypoxia [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A81.