Targeting heparanase/heparan sulfate proteoglycans by non‐anticoagulant heparins: Opportunities for innovative therapeutic approaches in sarcomas

Abstract Sarcomas are a heterogeneous group of aggressive mesenchymal malignancies. They account for 1% of all tumors in the general population and 15–20% in pediatric age and young adults. Despite differences in histology and pathobiology, the diverse types of sarcomas are traditionally managed with a common multi‐modal approach including surgery, radiotherapy, and aggressive polychemotherapy. Unfortunately, the prognosis for advanced or recurrent disease remains poor. Moreover, the disease rarity and a high cellular, molecular, and genetic/epigenetic heterogeneity make identification of therapeutic targets challenging. Therefore it remains an urgent need to identify effective therapies to improve patients' outcome. Common or peculiar biological motifs including deregulation of growth factor signaling, proangiogenic and promigratory pathways, tumor‐microenviroment interactions, transcriptional and epigenetic machinery, and differentiation program, provide actionable dependencies exploitable for therapeutic intervention. Among these, a deregulated heparan sulfate proteoglycan system due to aberrant expression of key components as well as structural/functional modifications mediated by endosulfatases and the endoβ‐ d ‐glycosidase heparanase, is emerging as a crucial player in tumor growth and progression and as a valuable therapeutic target across different sarcoma subtypes. In preclinical studies, non‐anticoagulant heparins have been shown to counteract the growth and metastatic dissemination of various sarcoma models according to their heparan sulfate mimetic and anti‐heparanase activities. Heparin derivatives also improved the anti‐sarcoma efficacy of molecularly targeted agents and cytotoxic drugs. In this minireview, we summarize the current knowledge about the interplay between the heparanase/heparan sulfate proteoglycan system and pathways involved in sarcomagenesis and disease progression. We illustrate the current understanding of the mechanisms of action of non‐anticoagulant heparins and the contribution of their anti‐heparanase, anti‐receptor tyrosine kinase, and likely immunomodulatory activities to their anti‐sarcoma effects. Finally, we discuss a few aspects worthy of exploration highlighting how elucidation of mechanisms underpinning antitumor activities of non‐anticoagulant heparin derivatives in the different sarcoma biological contexts may suggest new vulnerabilities and therapeutic approaches.