In the phase 1B component the investigators intend to enroll patients in a 3+3 dose escalation design. Newly diagnosed indolent and diffuse large cell lymphomas as well as relapsed/refractory indolent B cell lymphomas are eligible for enrollment in the phase 1 component. The primary end-point for this component would be to establish the recommended phase 2 dose (RP2D) for Selinexor in combination with standard dose RCHOP chemotherapy.