CLL tumor cells are highly dependent on the microenvironment where cytokines (eg, CD40L, BAFF, IL-4, IL-6), and contact (eg, stromal cells) promote cell activation and proliferation, and also resistance to spontaneous and drug-mediated apoptosis. Many of these microenvironment-activated pathways merge with TSPs exported by XPO1. XPO1 is therefore a highly attractive molecular target to explore in CLL, because it impacts multiple antitumor and growth suppressive signaling pathways that are dysregulated in this disease.