Olaratumab for soft tissue sarcoma

Current status of drugs targeting PDGF/PDGFR

As an important proangiogenic factor, platelet-derived growth factor (PDGF) and its receptor PDGFR are highly expressed in a variety of tumors, fibrosis, cardiovascular and neurodegenerative diseases. Targeting the PDGF/PDGFR pathway is therefore a promising therapeutic strategy. At present, a variety of PDGF/PDGFR targeted drugs with potential therapeutic effects have been developed, mainly including PDGF agonists, inhibitors targeting PDGFR and proteolysis targeting chimera (PROTACs). This review clarifies the structure, biological function and disease correlation of PDGF and PDGFR, and it discusses the current status of PDGFR-targeted drugs, so as to provide a reference for subsequent research.

Expression of Platelet Derived Growth Factor a, Its Receptor, and Integrin Subunit Alpha V in Feline Injection-Site Sarcomas

Injection-site sarcomas are considered an important entity in veterinary oncology, especially in cats. The current study investigated the immunohistochemical expression of platelet-derived growth factor A (PDGFA), platelet-derived growth factor receptor-α (PDGFR-α), and integrin alpha subunit v in feline injection-site sarcomas (FISS). A total of 14 paraffin-embedded tissue samples previously diagnosed as soft tissue sarcomas were selected from the departmental archive and sectioned at 5µm using a microtome. Tissue sections were stained with Hematoxylin & Eosin, Alcian blue-Periodic Acid Schiff (AB-PAS), Masson’s Trichrome, and immunohistochemically for PDGFA, PDGR-α, and integrin alpha v. The majority of the tumors were fibrosarcomas (n=13/14), except one case of myxoid liposarcoma. The tumors occurred at sites commonly used for injections or vaccine administration. Histologically, tumors were characterized by peripheral infiltration of mononuclear cells mainly lymphocytes, variable sized central necrotic areas, and many multinucleated tumor giant cells. AB-PAS staining revealed the presence of myxoid or mucinous areas in (8/14) tumors while trichrome staining demonstrated a variable amount of collagenous stroma in 12/14 tumors. Vimentin immunoreactivity was observed in all the tumors while smooth muscle actin and muscle actin staining was noticed in four and two cases, respectively. PDGFA and PDGFR-α immunoexpression was observed in all 14 cases while integrin alpha v in 13/14 cases. The results of the current study indicate that fibrosarcoma is the major morphologic phenotype of FISS. The PDGFA, its receptor, and integrin alpha v immunoexpression are increased in these tumors in cats which elucidates their role in the pathogenesis of FISS.

Expression of PDGF-A, PDGFRA, integrin subunit alpha V and selectin E is increased in canine cutaneous fibrosarcomas

We investigated the expression of platelet derived growth factor alpha (PDGFA); its receptor, PDGFRA; integrin subunit alpha V; and selectin E in cutaneous fibrosarcomas in dogs. Ten cases of canine fibrosarcomas were obtained from the archive of the Department of Pathology, Ondokuz Mayis University, Samsun. Tissue sections were cut and stained with hematoxylin and eosin, Alcian blue-periodic acid Schiff, Masson's trichrome, and also immunostained. Eight tumors classified as spontaneous fibrosarcomas exhibited interwoven bundles of spindle shaped cells with oval to plump nuclei and scant cytoplasm, while two tumors exhibited features of injection site fibrosarcoma with peripheral infiltration of mononuclear cells and intratumor necrosis. We found that neoplastic cells from all cases exhibited cytoplasmic expression of PDGFA, and cytoplasmic and nuclear staining for PDGFRA. Integrin subunit alpha V immunostaining was observed in all cases, while selectin E expression was observed in vascular endothelial cells and neoplastic cells. A significant positive correlation was found between the expression of PDGFA and integrin subunit alpha V. Our findings indicate that PDGFA, PDGFRA, integrin subunit alpha V and selectin E are expressed strongly in canine cutaneous fibrosarcomas and may contribute to tumor progression.