RecruitingDrug trialTargeting Residual Activity By Precision, Biomarker-Guided Combination Therapies of Multiple Sclerosis (TRAP-MS)Background: In people with multiple sclerosis (MS), brain and cerebrospinal fluid (CSF) biomarkers indicate inflammation or disease. Researchers want to see if 4 drugs given alone or combined affect MS biomarkers. They want to see if a change in biomarker levels can predict which drugs a person with MS might respond to. Objective: To see if signs of inflammation in CSF help predict a person s response to different drugs. Eligibility: People ages 18 and older who: * Are in protocol 09-I-0032 * Have progressive MS * Can stand and walk a few steps * Take an MS drug Design: Participants will be screened in protocol 09-I-0032. Participants will take 1 of the 4 study drugs. Researchers will call after 1 month to see how they are doing. Some will start a second drug. They may take each drug or combination for up to 18 months. Participants will have 2 visits a year for up to 6 years. Visits include: * Medical history * Physical exam * Blood and heart tests * X-rays and scans * Eye exam and tear collection * Lumbar puncture: A needle inserted between back bones removes some CSF. * Lymphocytapheresis: Blood is removed through a needle in one arm and run through a machine. The blood is returned through a needle in the other arm. * A sensor on the forehead records blood flow and oxygen use. * Participants may get a device for testing at home. Participants will stop taking the drugs if they have taken 2 drugs together for 18 months or if they do not do well on the drugs. Participants will be called 3 months later to see how they are doing.