Modeling the cumulative genetic risk for multiple sclerosis from genome-wide association data

BACKGROUND: Multiple sclerosis (MS) is the most common cause of chronic neurologic disability beginning in early to middle adult life. Results from recent genome-wide association studies (GWAS) have substantially lengthened the list of disease loci and provide convincing evidence supporting a multifactorial and polygenic model of inheritance. Nevertheless, the knowledge of MS genetics remains incomplete, with many risk alleles still to be revealed. METHODS: We used a discovery GWAS dataset (8,844 samples, 2,124 cases and 6,720 controls) and a multi-step logistic regression protocol to identify novel genetic associations. The emerging genetic profile included 350 independent markers and was used to calculate and estimate the cumulative genetic risk in an independent validation dataset (3,606 samples). Analysis of covariance (ANCOVA) was implemented to compare clinical characteristics of individuals with various degrees of genetic risk. Gene ontology and pathway enrichment analysis was done using the DAVID functional annotation tool, the GO Tree Machine, and the Pathway-Express profiling tool. RESULTS: In the discovery dataset, the median cumulative genetic risk (P-Hat) was 0.903 and 0.007 in the case and control groups, respectively, together with 79.9% classification sensitivity and 95.8% specificity. The identified profile shows a significant enrichment of genes involved in the immune response, cell adhesion, cell communication/signaling, nervous system development, and neuronal signaling, including ionotropic glutamate receptors, which have been implicated in the pathological mechanism driving neurodegeneration. In the validation dataset, the median cumulative genetic risk was 0.59 and 0.32 in the case and control groups, respectively, with classification sensitivity 62.3% and specificity 75.9%. No differences in disease progression or T2-lesion volumes were observed among four levels of predicted genetic risk groups (high, medium, low, misclassified). On the other hand, a significant difference (F = 2.75, P = 0.04) was detected for age of disease onset between the affected misclassified as controls (mean = 36 years) and the other three groups (high, 33.5 years; medium, 33.4 years; low, 33.1 years). CONCLUSIONS: The results are consistent with the polygenic model of inheritance. The cumulative genetic risk established using currently available genome-wide association data provides important insights into disease heterogeneity and completeness of current knowledge in MS genetics

Relapse and disability outcomes in patients with multiple sclerosis treated with fingolimod: subgroup analyses of the double-blind, randomised, placebo-controlled FREEDOMS study.

BACKGROUND: Fingolimod 0·5 mg once daily is approved for treatment of relapsing multiple sclerosis (MS). In the phase 3, 2-year FREEDOMS (FTY720 Research Evaluating Effects of Daily Oral therapy in MS) study, fingolimod significantly reduced annualised relapse rates (ARRs) and the risk of confirmed disability progression compared with placebo. We aimed to investigate whether the beneficial treatment effect reported for the overall population is consistent in subgroups of patients with different baseline characteristics. METHODS: We did subgroup analyses of ARRs (primary outcome) and confirmed disability progression (a secondary outcome) over 24 months in the FREEDOMS study, a randomised, double-blind study that included 1272 patients with relapsing-remitting MS who were assigned 1:1:1 to fingolimod (0·5 mg or 1·25 mg) or placebo once daily for 24 months. Subgroups were predefined, predefined and slightly modified, or defined post hoc, by demographic factors (including sex and age), disease characteristics (including baseline disability scores, relapse rates, and lesion parameters), and response to previous therapy (including analyses in patients eligible for fingolimod treatment according to the European label). Data were analysed by intention to treat. The FREEDOMS study is registered with ClinicalTrials.gov, number NCT00289978. FINDINGS: Treatment with fingolimod 0·5 mg was associated with significantly lower ARRs versus placebo across all subgroups except for patients aged over 40 years. ARR ratios ranged from 0·76 (95% CI 0·54-1·09; p=0·13) in patients aged over 40 years to 0·29 (0·16-0·52; p<0·0001) in patients who had relapse activity despite receiving interferon beta during the year before study enrolment. Hazard ratios for confirmed disability progression over 24 months with fingolimod 0·5 mg versus placebo ranged from 0·85 (95% CI 0·53-1·36; p=0·50) in patients with a T2 lesion volume of 3300 mm(3) or less to 0·32 (0·14-0·73; p=0·0066) in patients with an EDSS over 3·5. In patients who relapsed and had lesion activity despite treatment with interferon beta in the previous year, the ARR ratio for fingolimod 0·5 mg versus placebo was 0·38 (95% CI 0·21-0·68, p=0·0011), and for treatment-naive patients with rapidly evolving severe disease it was 0·33 (0·18-0·62, p=0·0006). Hazard ratios for confirmed disability progression over 24 months were 0·68 (0·29-1·62; p=0·39) and 0·73 (0·25-2·07; p=0·55), respectively, in these groups. INTERPRETATION: Patients with relapsing-remitting MS with a wide spectrum of clinical and MRI features including subgroups specified by the European label can potentially benefit from treatment with 0·5 mg fingolimod. FUNDING: Novartis

Correlation between brain volume loss and clinical and MRI outcomes in multiple sclerosis

OBJECTIVE: We investigated the determinants and clinical correlations of MRI-detected brain volume loss (BVL) among patients with relapsing-remitting multiple sclerosis from the phase 3 trials of fingolimod: FREEDOMS, FREEDOMS II, and TRANSFORMS. METHODS: Post hoc analyses were conducted in the intent-to-treat populations from each trial and in a combined dataset of 3,635 patients from the trials and their extensions. The relationship between brain volume changes and demographic, clinical, and MRI parameters was studied in pairwise correlations (Pearson) and in multiple regression models. The relative frequency of confirmed disability progression was evaluated in the combined dataset by strata of concurrent BVL at up to 4 years. RESULTS: Increasing age, disease duration, T2 lesion volume, T1-hypointense lesion volume, and disability were associated with reduced brain volume (p < 0.001, all). The strongest individual baseline predictors of on-study BVL were T2 lesion volume, gadolinium-enhancing lesion count, and T1-hypointense lesion volume (p < 0.01, all). During each study, BVL correlated most strongly with cumulative gadolinium-enhancing lesion count, new/enlarged T2 lesion count (p < 0.001, both), and number of confirmed on-study relapses (p < 0.01). Over 4 years in the combined dataset (mean exposure to study drug, 2.4 years), confirmed disability progression was most frequent in patients with greatest BVL. CONCLUSIONS: Rate of BVL in patients during the fingolimod trials correlated with disease severity at baseline and new disease activity on study, and was associated with worsening disability