ASPH Targeted Therapy for Chondrosarcoma

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PROJECT SUMMARY/ABSTRACT The long-term objective of this application is to improve the survival and quality of life for patients with chondrosarcoma, a primary malignant bone tumor desperately in need of more effective treatments. The five- year survival for chondrosarcoma, the most common bone sarcoma in adults, is an abysmal 10-25%, with most patients succumbing to pulmonary metastases. Conventional cytotoxic chemotherapy has no effect on chondrosarcoma, so the current standard of care is surgical resection. There has been no improvement in the cure rate for chondrosarcoma in the last several decades. The goal of this proposal is to systematically evaluate promising new treatment strategies that target aspartate β-hydroxylase (ASPH), a transmembrane protein that is normally expressed during embryonic development, but not after birth. We have found that ASPH is re- expressed in chondrosarcoma. In some carcinomas, ASPH signals through the Notch pathway to influence the expression of matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF), which support cell proliferation, invasion, and metastasis. We have data suggesting that ASPH functions similarly in chondrosarcoma. ASPH is highly expressed in >90% of chondrosarcomas, as are activated Notch and multiple MMPs, and high ASPH expression correlates positively with tumor grade and poor long-term survival. Inhibition of Notch is a long sought after but, as of yet, unachieved goal in cancer treatment. The work in this proposal will advance ASPH as a potential therapeutic target by determining the relationship between ASPH and Notch in chondrosarcoma. First, ASPH levels in human chondrosarcoma cell lines will be modulated using CRISPR-Cas9 gene editing, followed by treatment with a proven small molecule inhibitor (SMI) of ASPH. Changes in proliferation, invasion, apoptosis, and Notch signaling will be used as mechanistic readouts of ASPH signaling in vitro. Notch signaling will be manipulated in these ASPH-modulated cell lines with gain and loss of function approaches to evaluate the role of Notch in ASPH signaling (Aim 1). Second, the role of ASPH and Notch in chemotherapy resistance will be evaluated in human chondrosarcoma cell lines, and the ability of the SMI and an ASPH-targeted antibody-drug conjugate (ADC) to enhance doxorubicin efficacy will be tested (Aim 2). Finally, three different approaches to targeting ASPH will be evaluated in vivo using mouse chondrosarcoma models: SMI inhibition of ASPH, SMI + doxorubicin, and an antibody-drug conjugate targeting ASPH linked to emtansine (Aim 3). The completion of these aims will provide important insight into the biology of chondrosarcoma and determine whether the therapeutic targeting of ASPH has potential as an effective strategy for the treatment of these malignancies. The results may also have wider impact and be applicable to patients with other types of bone and soft tissue sarcomas.