Vorolanib (X-82), an oral anti-VEGFR/PDGFR/CSF1R tyrosine kinase inhibitor, with everolimus in solid tumors: results of a phase I study

Background Anti-vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKI) combined with mTOR inhibitors, like everolimus, result in significant responses and prolonged progression-free survival (PFS) among patients with renal cell carcinoma (RCC) [1]. However, everolimus doses >5 mg are often not tolerated when combined with other TKIs^2,3. Vorolanib (X-82), an oral anti-VEGFR/platelet derived growth factor receptor (PDGFR)/colony stimulating factor 1 receptor (CSF1R) multitarget TKI, has a short half-life and limited tissue accumulation. We conducted a Phase 1 study of vorolanib with everolimus (10 mg daily) in patients with solid tumors. Methods A 3 + 3 dose escalation design was utilized to determine dose limiting toxicities (DLT) and recommended Phase 2 dose (RP2D) of vorolanib/everolimus. Oral vorolanib at 100, 150, 200, 300, or 400 mg was combined with 10 mg oral everolimus daily. The phase 2 portion was terminated after enrolling two patients due to funding. Results Eighteen patients were evaluable for DLT among 22 treated subjects. Observed DLTs were grade 3 fatigue, hypophosphatemia, and mucositis. The RP2D is vorolanib 300 mg with everolimus 10 mg daily. In 15 patients evaluable for response, three had partial response (PR; 2 RCC, 1 neuroendocrine tumor [NET]) and eight had stable disease (SD; 2 RCC, 6 NET). Conclusions Vorolanib can safely be combined with everolimus. Encouraging activity is seen in RCC and NET. Further studies are warranted. Trial Registration Number: NCT01784861.