In vitro activity: Verdinexor inhibits the viability of Jurkat, OCI-Ly3, OCI-Ly10, and CLBL1 cells with IC50 of 0.3 nM, 2.1 nM, 41.8 nM, and 8.5 nM, respectively. KPT-335 also induces apoptosis in CLBL1 cells and primary canine DLBCL cells that express XPO1 and SINE. Verdinexor potently and selectively inhibits vRNP export and effectively inhibits the replication of various influenza virus A and B strains, including pandemic H1N1 virus, highly pathogenic H5N1 avian influenza virus, and the recently emerged H7N9 strain.

Cell Assay: Cell viability for lymphoid lines is determined by the MTS assay using CellTiter 96® AQueous One Solution Cell Proliferation Assay Kit. Briefly, for lymphoid cell lines, 5×104 cells (or 1×105 primary DLBCL cells) are cultured in 100 µL of complete medium in 96-well plates in the presence of SINE compounds. After 72 hours, 20 µL of MTS solution is added to each well and cells are incubated for another 4 hours before measuring absorbance at 490 nm using a Wallac Victor 1420 Multilabel Counter. The IC50 of SINE is calculated using Prism 6 software. For the non-lymphoid cell lines, 96 well plates are seeded in triplicate in 90 µL with 2500 cells/well of OSA16, 5000 cells/well of C2, and 2500 cells/well of 323610-3. Seeded plates are cultured overnight then treated the following day with 10 µL of KPT-214 in C10 media at concentrations of 0.0001, 0.01, 0.1, 1.0, and 10 µM. Plates are collected at 92 hours, centrifuged at 1300 rpm, and supernatant is removed by inverting plates on absorbent paper. Plates are then sealed and immediately placed at −80°C for a minimum of 12 hours. Plates are then thawed and CyQUANT ®Cell Proliferation Assay is performed following the manufacturer’s protocol. Briefly, 200 µL of the diluted working CyQUANT solution is added to each well and protected from light. Fluorescence is the measured using a SpectraMax M2 microplate reader at 480 nm excitation and 520 nm emission. Results are represented as percent of control, or plotted to calculate IC50 values at 92 hours.