Colon stroma mediates an inflammation-driven fibroblastic response controlling matrix remodeling and healing

Chronic inflammation is often associated with the development of tissue fibrosis, but how mesenchymal cell responses dictate pathological fibrosis versus resolution and healing remains unclear. Defining stromal heterogeneity and identifying molecular circuits driving extracellular matrix deposition and remodeling stands to illuminate the relationship between inflammation, fibrosis, and healing. We performed single-cell RNA-sequencing of colon-derived stromal cells and identified distinct classes of fibroblasts with gene signatures that are differentially regulated by chronic inflammation, including IL-11-producing inflammatory fibroblasts. We further identify a transcriptional program associated with trans-differentiation of mucosa-associated fibroblasts and define a functional gene signature associated with matrix deposition and remodeling in the inflamed colon. Our analysis supports a critical role for the metalloprotease Adamdec1 at the interface between tissue remodeling and healing during colitis, demonstrating its requirement for colon epithelial integrity. These findings provide mechanistic insight into how inflammation perturbs stromal cell behaviors to drive fibroblastic responses controlling mucosal matrix remodeling and healing.

PAX8 lineage-driven T cell engaging antibody for the treatment of high-grade serous ovarian cancer

High-grade serous ovarian cancers (HGSOC) represent the most common subtype of ovarian malignancies. Due to the frequency of late-stage diagnosis and high rates of recurrence following standard of care treatments, novel therapies are needed to promote durable responses. We investigated the anti-tumor activity of CD3 T cell engaging bispecific antibodies (TCBs) directed against the PAX8 lineage-driven HGSOC tumor antigen LYPD1 and demonstrated that anti-LYPD1 TCBs induce T cell activation and promote in vivo tumor growth inhibition in LYPD1-expressing HGSOC. To selectively target LYPD1-expressing tumor cells with high expression while sparing cells with low expression, we coupled bivalent low-affinity anti-LYPD1 antigen-binding fragments (Fabs) with the anti-CD3 scFv. In contrast to the monovalent anti-LYPD1 high-affinity TCB (VHP354), the bivalent low-affinity anti-LYPD1 TCB (QZC131) demonstrated antigen density-dependent selectivity and showed tolerability in cynomolgus monkeys at the maximum dose tested of 3 mg/kg. Collectively, these data demonstrate that bivalent TCBs directed against LYPD1 have compelling efficacy and safety profiles to support its use as a treatment for high-grade serous ovarian cancers.

SHP2 blockade enhances anti-tumor immunity via tumor cell intrinsic and extrinsic mechanisms

SHP2 is a ubiquitous tyrosine phosphatase involved in regulating both tumor and immune cell signaling. In this study, we discovered a novel immune modulatory function of SHP2. Targeting this protein with allosteric SHP2 inhibitors promoted anti-tumor immunity, including enhancing T cell cytotoxic function and immune-mediated tumor regression. Knockout of SHP2 using CRISPR/Cas9 gene editing showed that targeting SHP2 in cancer cells contributes to this immune response. Inhibition of SHP2 activity augmented tumor intrinsic IFNγ signaling resulting in enhanced chemoattractant cytokine release and cytotoxic T cell recruitment, as well as increased expression of MHC Class I and PD-L1 on the cancer cell surface. Furthermore, SHP2 inhibition diminished the differentiation and inhibitory function of immune suppressive myeloid cells in the tumor microenvironment. SHP2 inhibition enhanced responses to anti-PD-1 blockade in syngeneic mouse models. Overall, our study reveals novel functions of SHP2 in tumor immunity and proposes that targeting SHP2 is a promising strategy for cancer immunotherapy.

Abstract IA23: Microenvironmental regulation of antitumor immune responses: A lesson from fibroblastic cells

Despite the reported clinical benefits of checkpoint blockade in some cancers, a large proportion of patients fail to respond, and insights from preclinical and clinical studies have indicated that therapy failure may stem from cues emanating from the tumor microenvironment. Strikingly, resistance to PD-1 immunotherapy in patients with metastatic melanoma has been associated with the presence of a transcriptional signature which includes genes connected to wound healing and angiogenesis, suggesting that targeting stromal elements of the tumor microenvironment has the potential to extend the therapeutic window of immunotherapies. The development of strategic therapeutics, however, is likely to depend on the identification of the cellular and molecular mechanisms governing stromal-imposed immune paralysis. In an effort to gain a better understanding on how stromal elements can modulate antitumor immune responses, we have conducted a comprehensive transcriptomic and functional analysis of stromal cells from murine tumors, which enabled the identification of a discrete population of mesenchymal cells bearing striking similarities to fibroblastic reticular cells of lymphoid organs, including expression of podoplanin and high fibrogenic potential. Our data revealed that within tumors, the reticular matrix laid by myofibroblasts promotes the compartmentalization of tumor-infiltrating leukocytes in peritumoral areas and the establishment of a dynamic interplay between T cells and stroma. Functionally, these interactions prompt stromal secretion of nitric oxide that hinders proliferation of lymphocytes, supporting that tumor fibroblasts contribute to immunosuppression by creating and restraining lymphocytes in non-permissive domains of the tumor microenvironment. Accordingly, displacement of T cells from peritumoral areas through the targeting of stroma-deposited collagen fibers augments natural antitumor immune responses and delays tumor progression in immune-competent mice, but not in lymphopenic mice. Collectively, these data shed light on the mechanisms of stroma-mediated immunomodulation in tumors, highlighting a population of lymphoid-like mesenchymal cells with fibrogenic and immunosuppressive potential. Perhaps more importantly, our study suggests that modulating the extracellular matrix has profound consequences on the spatial and functional fate of tumor-infiltrating lymphocytes, supporting that targeting tumor fibrotic responses may represent a valuable approach to complement current immunotherapies and extend their clinical benefits.

Citation Format: Viviana Cremasco, Angelo Grauel, Michael Wu, Jillian Astarita, Matthew Woodruff, Zohreh Amoozgar, Lotte Spel, Flavian Brown, Michael Carroll, Kenzie MacIsaac, Glenn Dranoff, Shannon Turley. Microenvironmental regulation of antitumor immune responses: A lesson from fibroblastic cells [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr IA23.

IL4RA on lymphatic endothelial cells promotes T cell egress during sclerodermatous graft versus host disease

Systemic sclerosis (SSc) is a potentially fatal autoimmune disorder with limited therapeutic options. Sclerodermatous graft versus host disease (sclGvHD), induced by transfer of B10.D2 splenocytes into BALB/c Rag2-/- mice, models an inflammatory subset of SSc characterized by a prominent IL13-induced gene expression signature in the skin. Host mice deficient in IL4RA, a subunit of the type II IL4/IL13 receptor, are protected from sclGvHD. While IL4RA has a well-established role in Th2 differentiation and alternative macrophage activation, we report here a previously unappreciated function for IL4RA in lymphatic endothelial cells (LECs): regulation of activated T cell egress. Seven days after splenocyte transfer, Il4ra-/- hosts had increased numbers of activated graft CD4+ T cells in skin draining lymph nodes (dLNs) but fewer T cells in efferent lymph, blood, and skin. Sphingosine-1 phosphate (S1P), master regulator of lymphocyte egress from LNs, was lower in dLNs of Il4ra-/- hosts with a corresponding decrease of S1P kinase 1 (Sphk1) expression in LECs. Bypassing the efferent lymphatics via i.v. injection of CD4+ T cells from dLNs of Il4ra-/- sclGvHD mice restored clinical GvHD in secondary Il4ra-/- recipients. These results identify a role for IL4RA and suggest that modulation of lymphocyte egress from LNs may be effective in SSc and GvHD.