The primary endpoint of the study will be fatigue severity as measured by the MFIS score, between 26th and 35th day of each treatment period (while the patient is taking the maximal tolerated or target dose). The MFIS is a validated patient-reported outcome. The questionnaire will be administered remotely (through internet, phone or mailed forms) and the participants can answer the questions in few minutes while at home or at their work place. The questionnaire has been validated in English and Spanish.