A Randomized Phase 2 Trial of Axitinib and TRC105 Versus Axitinib Alone (Including a lead-in Phase 1B Dose Escalation Portion) in Patients With Advanced or Metastatic Renal Cell Carcinoma

Axitinib 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. Axitinib is approved for the treatment of advanced renal cell carcinoma, following progression on one prior systemic therapy. TRC105 is an antibody to CD105, an important angiogenic target on vascular endothelial cells that is distinct from VEGFR. TRC105 inhibits angiogenesis, tumor growth and metastases in preclinical models and complements the activity of bevacizumab and multi-kinase inhibitors that target VEGFR. In a phase 1 study of advanced solid tumors,TRC105 therapy caused a global reduction in angiogenic biomarkers and reduced tumor burden at doses that were well-tolerated. By targeting a non-VEGF pathway that is upregulated following VEGF inhibition, TRC105 has the potential to complement VEGF inhibitors and could represent a major advance in cancer therapy. TRC105 potentiates bevacizumab and VEGFR tyrosine kinases (VEGFR TKI) in preclinical models. In a phase 1b study, the combination of TRC105 and bevacizumab produced radiographic reductions in tumor volume in bevacizumab refractory patients. Together, the use of TRC105 with axitinib may result in more effective angiogenesis inhibition and improved clinical efficacy over that seen with axitinib alone.