Study to Evaluate the Reduction of Cardiac Problems in Multiple Sclerosis Patients With Mitoxantrone and Dexrazoxane in Combination

Inclusion Criteria: * Written informed consent to participate in the study * Male or female subject is 18 years of age to 55 years of age * Subject must have one of the below mentioned confirmed diagnoses of Multiple Sclerosis: RRMS or CPMS according to rev. McDonald Criteria (2005) * If female of childbearing potential: Will to practice reliable birth control measures during study treatment and for at least 6 months after completion of study medication; not lactating or pregnant; and has a documented negative pregnancy test result within 72 hours prior to study medication administration. Male study participants: Will to practice reliable birth control measures during study treatment and for at least 6 months after completion of study medication * Subject is willing to participate in the study, follow protocol study treatment regimen, and comply with all planned assessments * Mitoxantrone treatment indication is given according to current guidelines: * Relapsing progressive or secondary progressive MS with/without superimposed relapses * EDSS 3-6; EDSS deterioration ≥1 point over last 18 months or 2 relapses * non-response or non-tolerability of pre-treatment * ≥ 48 mg/m² BSA MX dose received up to baseline visit as lifetime dosage before study entry. If the patient is under regular ongoing MX treatment, the infusion interval of 3 months must be obtained (see exclusion criteria) Exclusion Criteria: * Concomitant clinically suspected or confirmed neurologic disorder at study entry that may interfere with the evaluation in this protocol \[i.e. EDSS, MSFC, MEP or MRI measurements\] * Pre-Treatment with DRZ or immunosuppressive drugs of the anthracycline family with cardiotoxic potential other than MX prior to study enrollment * Last Treatment with MX within the past 84 days prior to study enrollment (regular 3-monthly intervals must be obtained) * History of hypersensitivity to any of the study drugs or to drugs with similar chemical structures * Pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive HCG laboratory test (\>5 mIU/ml) * Unwillingness to perform adequate contraception * Use of other investigational drugs at the time of enrollment, or within 30 days or 5 half-lives of enrollment, whichever is longer * Subjects unable or unwilling to adhere to the study-designated procedures and restrictions * Patients not able to perform cardiac/neurological investigations including MRI, e.g. hypersensitivity to MRI contrast agent * Other known contraindication for DRZ or MX according to current labelling * Subject has a pre-existing cardiac disease interfering with left ventricular ejection fraction, i.e. cardiac insufficience for different reasons (resulting from prior cardial conditions such as myocardial infarction, myocarditis) * Routine co-administration of cortisone-pulse therapy (other than for treatment of relapses), intrathecal triamcinolone-therapy or other off-label/ investigational agents (e.g. fampridine, aminopyridine) * History of malignancy in the past 5 years (excluding localized basal cell carcinoma of the skin) * Pre-Treatment with other immunosuppressive drugs (azathioprine, methotrexate, mycophenolate, cyclophosphamide) within the past 3 months * Pre-Treatment with monoclonal antibodies (natalizumab, rituximab) within the past 6 months