Medications are modestly effective at decreasing the number of attacks in RRMS and in reducing the accumulation of brain lesions, which is measured using gadolinium - enhanced magnetic resonance imaging (MRI).  Interferons and glatiramer acetate are roughly equivalent, reducing relapses by approximately 30% and their safe profile make them the first-line treatments.  Nevertheless, not all the patients are responsive to these therapies. It is known that 30% of MS patients are non-responsive to Beta interferon.  One of the factors related to non-respondance is the presence of high levels of interferon beta neutralizing antibodies . Interferon therapy, and specially interferon beta-1b, induces the production of neutralizing antibodies, usually in the second 6 months of treatment, in 5 to 30% of treated patients.   Moreover, a subset of RRMS patients with specially active MS, sometimes called "rapidly worsening MS" are normally non-responders to immunomodulators and are treated with either mitoxantrone or natalizumab. 
Bailey et al (2012) summarized the current state of evidence for combination topical and systemic therapies for mild-to-severe psoriasis. These researchers performed a systematic search for all entries in PubMed, CINAHL, Cochrane Review, and EMBASE related to combination treatments for psoriasis through July 2010. They included randomized controlled trials that reported proportion of disease clearance or mean change in clinical severity score (or provided these data through communication with study authors) for efficacy of a combination treatment for psoriasis compared with 1 or more corresponding monotherapies. Study data were extracted by 3 independent investigators, with disagreement resolved by consensus. The proportion of patients who achieved clearance, definition of clearance, means and standard deviations for baseline disease symptom score and final disease symptom score, and major design characteristics were extracted for each study. Combination treatments consisting of vitamin D derivative and corticosteroid, vitamin D derivative and UV-B, vitamin A derivative and psoralen-UV-A, vitamin A derivative and corticosteroid, vitamin A derivative and UV-B, corticosteroid and hydrocolloid occlusion dressings, UV-B and alefacept, as well as vitamins A and D derivatives were more effective than 1 or more monotherapies using the likelihood of clearance as the outcome. Blinding status and potency of the corticosteroid treatment used were significant sources of heterogeneity between studies. The authors concluded that these findings demonstrated the need for additional long-term trials with standardized outcome measures to evaluate the efficacy and adverse effects of combination therapies for psoriasis and highlighted the possible effects of trial design characteristics on results.