Predictive parameters of mitoxantrone effectiveness in the treatment of multiple sclerosis

Introduction: In a number of controlled trials it was established that mitoxantrone has a beneficial effect on disease progression in multiple sclerosis (MS) patients with a worsening disease course. The aim of this study was to investigate the use of mitoxantrone in clinical practice, and especially to describe predictive parameters of its effectiveness under these conditions. Objectives and methods: In a retrospective, open-label mitoxantrone study we analysed 94 MS patients (49% relapsing-remitting MS (RRMS), 41% secondary progressive MS and 10% primary progressive MS) who received monthly 20 mg i.v. mitoxantrone and 1 g i.v. methylprednisolone for six months, and selected as a criterion of effectiveness the percentage of patients with an Expanded Disability Status Scale (EDSS) improvement of at least one point (confirmed after one year) after stopping the treatment. A multivariate analysis was undertaken to assess the predictive value of five parameters on mitoxantrone effectiveness: (1) total number of relapses since disease onset and before treatment, (2) number of relapses within the past 24 months before treatment, (3) number of relapses in separate areas within the past 24 months before treatment, (4) active MRI scans (including Gd-enhanced lesions), and (5) clinical course of MS. Results: During the observation period from 1 January 1997 to 30 May 2000 more than 44% of the patients improved by one point or more on the EDSS (confirmed after one year), 39% remained stable and 17% deteriorated. In patients with a RRMS course three or more relapses within the past 24 months preceding treatment, and at least one Gd-enhancing lesion resulted in a strong relative benefit (i.e., relative risk) of mitoxantrone effectiveness. In contrast, total number of relapses since disease onset had no impact on disease evolution and disability progression. Multivariate analysis revealed the number of relapses in separate areas within the past 24 months before treatment as the strongest predictive parameter (P < 0.001). Conclusion: Mitoxantrone is effective in improving and stabilizing patients with a worsening MS course in routine clinical practice. Several strong predictive parameters of mitoxantrone effectiveness were investigated among which the number of relapses in separate clinical improvement.