Pre-clinical model studies supported that the combination of PRX177561 (CXC4, chemokine receptor type 4 antagonist) with sunitinib enhanced the therapeutic efficacy (reducing the tumor proliferation and extending the disease-free survival) against glioblastoma (brain cancer).47,48In vivo studies supported that a COX-2 (cyclooxygenase-2) inhibitor (celecoxib 11) can enhance the activity of sunitinib in mice bearing human renal cancer xenografts via the observation of delay in tumor progression.49 This evidence concerns the gene PTGS2 and neoplasm.