Karyopharm Therapeutics Inc. Karyopharm Therapeutics Inc is a commercial-stage pharmaceutical company focused on novel cancer therapies and dedicated to the discovery, development, and commercialization of drugs directed against nuclear export for the treatment of cancer and other diseases. The company conducts research focused on intracellular communication between the nucleus and cytoplasm and has developed small-molecule compounds that inhibit exportin 1 (XPO1), a nuclear export protein. It is focused on marketing XPOVIO (selinexor).