Abstract B007: Remodeling the hyaluronan-rich tumor extracellular matrix using hyaluronidase-expressing genetically engineered MSCs for tumor regression and metastasis prevention in sarcomas
Authors: Browne Alice , Clements Miranda , Ju Wei , Brock Daniel , Kaplan Rosandra 
Published: January 2023

Abstract
Sarcomas are a diverse group of rare malignant tumors the develop in the bone and connective tissue and are often aggressive with ~50% of patients developing metastases. Due to their rarity and diversity, there is a great lack of standard therapies resulting in a 65% and 15% 5-year survival rate for regional and metastatic disease, respectively. Tumorigenesis is largely influenced by communication between the tumor microenvironment (TME), cancer cells, and the extracellular matrix (ECM). The ECM promotes cancer initiation and dissemination from the primary tumor and fosters a favorable microenvironment for metastatic colonization of tumor cells. Due to their mesenchymal origin, sarcomas are thought to produce and deposit large quantities of ECM. One component of the tumor-ECM known to promote an aggressive cancer phenotype is hyaluronan (HA). Abundant HA in the TME arises from overactive HA synthases that produce HA or downregulation of hyaluronidases (Hyals) that catalyze HA degradation. HA-rich tumor ECM promote cancer progression by regulating chemokine and cytokine trafficking, increasing hypoxia and interstitial pressure, and limiting delivery of antitumor therapies. In-silico profiling of sarcomas revealed an increase in HA synthase mRNA expression in 50.78% and correlated with 35% decrease in overall patient survival (P = 0.0027), compared to sarcomas with low HA synthase expression. To target this HA-rich tumor ECM, we sought to develop a cell-based approach to locally deliver HA-remodeling enzymes to minimize the drawbacks of systemic therapy and enhance anti-tumor responses. We developed genetically engineered mesenchymal stromal cells (GEMesys) that express Hyal, using mesenchymal stem cells derived from mouse lungs. We hypothesized that the Hyal-GEMesys would home to and degrade the HA-rich ECM preventing cancer progression. The therapeutic efficacy of Hyal-GEMesys was tested in osteosarcoma (F42010) and rhabdomyosarcoma (M-3-9M) syngeneic murine models. Preliminary data demonstrated encouraging efficacy of Hyal-GEMesys in reducing tumor volume in the osteosarcoma (up to 1.4-fold, p=0.0035-0.0172) and rhabdomyosarcoma M-3-9M model (up to 2-fold, P= 0.0428). Further, analysis of osteosarcoma tumors revealed reduced HA (up to 2.3-fold, P=0.0078) and collagen-I content (up to 3-fold, P= 0.0025) indicating our Hyal-GEMesys functionally remodel the ECM in vivo. Changes in ECM in GEMesy treated group were associated with changes in immune infiltration with an increase in CD4+ (P=0.0221) and CD8+ (P=0.0087) T cells and a decrease in IBA1+ (P=0.0144) macrophages. Analysis of rhabdomyosarcoma tumors revealed reduced HA content (up to 2-fold, P-0.00206). Future studies will more deeply explore the mechanisms of ECM-mediated immune changes and impact on metastatic progression. Our cell-based approach to deliver hyaluronidases holds promise of effectively degrading and remodel the HA-rich tumor ECM to enhance anti-tumor responses, prevent metastases and improve clinical outcomes for patients with high-risk sarcoma malignancies.
Citation Format: Alice Browne, Miranda Clements, Wei Ju, Daniel Brock, Rosandra Kaplan. Remodeling the hyaluronan-rich tumor extracellular matrix using hyaluronidase-expressing genetically engineered MSCs for tumor regression and metastasis prevention in sarcomas [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B007.