Trial of TRC105 and Pazopanib Versus Pazopanib Alone in Patients With Advanced Angiosarcoma

TRC105 (carotuximab) is a monoclonal antibody to endoglin (CD105), an essential angiogenic target highly expressed on tumor vessels that is distinct from VEGFR. Endoglin is also expressed directly on tumor cells in angiosarcoma and is upregulated following VEGF inhibition. TRC105 inhibits angiogenesis, tumor growth and metastases in preclinical models and complements the activity of bevacizumab and multi-kinase inhibitors that target the VEGFR. Pazopanib is an oral inhibitor of multiple receptor tyrosine kinases, including vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, and VEGFR-3 at therapeutic plasma concentrations. These receptors are implicated in pathologic angiogenesis, tumor growth, and cancer progression. By targeting a non-VEGF pathway that is upregulated following VEGF inhibition, TRC105 has the potential to complement VEGFR tyrosine kinase inhibitors (TKIs) and could represent a major advance in the treatment of angiosarcoma. Together, the use of TRC105 with pazopanib may result in more effective angiogenesis inhibition and improved clinical efficacy over that seen with pazopanib alone.