Evidence from both in vitro and in vivo experiments indicates that BAY87-2243 has anti-tumor effects and enhances the efficacy of fludarabine and ibrutinib in CLL, independent of functional TP53. 114Hence, Seiffert concluded that CLL cells whose TP53 was destroyed by HIF-1α inhibition are sensitive to fludarabine therapy. This evidence concerns the gene HIF1A and B-cell chronic lymphocytic leukemia.