Autologous Ex Vivo Lentiviral Gene Therapy for Adenosine Deaminase Deficiency.

BACKGROUND: Severe combined immunodeficiency due to adenosine deaminase (ADA) deficiency (ADA-SCID) is a rare and life-threatening primary immunodeficiency. METHODS: We treated 50 patients with ADA-SCID (30 in the United States and 20 in the United Kingdom) with an investigational gene therapy composed of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) transduced ex vivo with a self-inactivating lentiviral vector encoding human ADA. Data from the two U.S. studies (in which fresh and cryopreserved formulations were used) at 24 months of follow-up were analyzed alongside data from the U.K. study (in which a fresh formulation was used) at 36 months of follow-up. RESULTS: Overall survival was 100% in all studies up to 24 and 36 months. Event-free survival (in the absence of reinitiation of enzyme-replacement therapy or rescue allogeneic hematopoietic stem-cell transplantation) was 97% (U.S. studies) and 100% (U.K. study) at 12 months; 97% and 95%, respectively, at 24 months; and 95% (U.K. study) at 36 months. Engraftment of genetically modified HSPCs persisted in 29 of 30 patients in the U.S. studies and in 19 of 20 patients in the U.K. study. Patients had sustained metabolic detoxification and normalization of ADA activity levels. Immune reconstitution was robust, with 90% of the patients in the U.S. studies and 100% of those in the U.K. study discontinuing immunoglobulin-replacement therapy by 24 months and 36 months, respectively. No evidence of monoclonal expansion, leukoproliferative complications, or emergence of replication-competent lentivirus was noted, and no events of autoimmunity or graft-versus-host disease occurred. Most adverse events were of low grade. CONCLUSIONS: Treatment of ADA-SCID with ex vivo lentiviral HSPC gene therapy resulted in high overall and event-free survival with sustained ADA expression, metabolic correction, and functional immune reconstitution. (Funded by the National Institutes of Health and others; ClinicalTrials.gov numbers, NCT01852071, NCT02999984, and NCT01380990.).

Best practice for analysis of shared clinical trial data.

BACKGROUND: Greater transparency, including sharing of patient-level data for further research, is an increasingly important topic for organisations who sponsor, fund and conduct clinical trials. This is a major paradigm shift with the aim of maximising the value of patient-level data from clinical trials for the benefit of future patients and society. We consider the analysis of shared clinical trial data in three broad categories: (1) reanalysis - further investigation of the efficacy and safety of the randomized intervention, (2) meta-analysis, and (3) supplemental analysis for a research question that is not directly assessing the randomized intervention. DISCUSSION: In order to support appropriate interpretation and limit the risk of misleading findings, analysis of shared clinical trial data should have a pre-specified analysis plan. However, it is not generally possible to limit bias and control multiplicity to the extent that is possible in the original trial design, conduct and analysis, and this should be acknowledged and taken into account when interpreting results. We highlight a number of areas where specific considerations arise in planning, conducting, interpreting and reporting analyses of shared clinical trial data. A key issue is that that these analyses essentially share many of the limitations of any post hoc analyses beyond the original specified analyses. The use of individual patient data in meta-analysis can provide increased precision and reduce bias. Supplemental analyses are subject to many of the same issues that arise in broader epidemiological analyses. Specific discussion topics are addressed within each of these areas. Increased provision of patient-level data from industry and academic-led clinical trials for secondary research can benefit future patients and society. Responsible data sharing, including transparency of the research objectives, analysis plans and of the results will support appropriate interpretation and help to address the risk of misleading results and avoid unfounded health scares.

Timed 25-foot walk: direct evidence that improving 20% or greater is clinically meaningful in MS.

OBJECTIVE: In this study, we used data from clinical trials of dalfampridine (fampridine outside the United States) to re-examine the clinical meaningfulness of Timed 25-Foot Walk (T25FW) changes. METHODS: Pooled data were analyzed from 2 phase III randomized placebo-controlled clinical trials of dalfampridine in multiple sclerosis (MS) (n = 533). Walking speed (T25FW) and patient-reported walking ability (MS Walking Scale-12 [MSWS-12]) were measured, concurrently, multiple times before and during treatment. We examined T25FW speed variability within and between visits, correlations of T25FW speed with MSWS-12 score, and changes in MSWS-12 (mean scores, effect sizes) associated with percent T25FW changes. RESULTS: T25FW speed variability was small (within- and between-visit averages = 7.2%-8.7% and 14.4%-16.3%). Correlations between T25FW and MSWS-12 values were low (-0.20 to -0.30), but relatively stronger between their change values (-0.33 to -0.41). Speed improvements of >20%, and possibly 15%, were associated with clinically meaningful changes in self-reported walking ability using MSWS-12 change score and effect size criteria. CONCLUSIONS: This study builds on existing research and provides direct evidence that improvements in T25FW speed of ≥ 20% are meaningful to people with MS. The dalfampridine data enabled examinations previously not possible, including spontaneous and induced speed changes, speed change anchored to change in self-reported walking ability, and a profile of speed changes. Results support the T25FW as a clinically meaningful outcome measure for MS clinical trials.

Additional efficacy endpoints from pivotal natalizumab trials in relapsing-remitting MS.

Standard clinical endpoints in multiple sclerosis (MS) studies, such as disability progression defined by the expanded disability status scale (EDSS) and annualized relapse rate, may not fully reflect all aspects of therapeutic benefit experienced by patients. Pivotal studies showed that natalizumab is effective both as monotherapy (AFFIRM study) and in combination with interferon beta-1a (IFNß-1a) (SENTINEL study) in patients with relapsing MS. We present AFFIRM and SENTINEL data demonstrating the efficacy of natalizumab on prespecified tertiary endpoints, including extent of confirmed change in EDSS score from baseline, time to sustained progression to EDSS milestone scores, hospitalizations, corticosteroid use, and time to confirmed progression of cognitive deficits. Natalizumab significantly reduced changes in EDSS scores (P < 0.001) and proportion of patients progressing to an EDSS score ≥4.0 (P < 0.001) and ≥6.0 (P = 0.002) compared with placebo. Natalizumab + IFNß-1a significantly reduced changes in EDSS scores compared with placebo + IFNß-1a (P = 0.011). Based on 0.5 standard deviation change in paced auditory serial addition test-3 score, natalizumab treatment reduced the risk of confirmed progression of cognitive deficits by 43% compared with placebo (HR 0.57 [95% CI 0.37, 0.89], P = 0.013); however, no significant difference between groups was seen in SENTINEL. Natalizumab, both as monotherapy and in combination with IFNß-1a, significantly reduced the annualized rate of MS-related hospitalizations (by 64 and 61%, respectively) and the annualized rate of relapses severe enough to require steroid treatment (by 69 and 61%, respectively) compared with placebo and placebo + IFNß-1a (P < 0.001). These analyses underline beneficial effects of natalizumab therapy in relapsing MS patients.

Natalizumab plus interferon beta-1a reduces lesion formation in relapsing multiple sclerosis.

The SENTINEL study showed that the addition of natalizumab improved outcomes for patients with relapsing multiple sclerosis (MS) who had experienced disease activity while receiving interferon beta-1a (IFNbeta-1a) alone. Previously unreported secondary and tertiary magnetic resonance imaging (MRI) measures are presented here. Patients received natalizumab 300 mg (n=589) or placebo (n=582) intravenously every 4 weeks plus IFNbeta-1a 30 microg intramuscularly once weekly. Annual MRI scans allowed comparison of a range of MRI end points versus baseline. Over 2 years, 67% of patients receiving natalizumab plus IFNbeta-1a remained free of new or enlarging T2-lesions compared with 30% of patients receiving IFNbeta-1a alone. The mean change from baseline in T2 lesion volume over 2 years decreased in patients receiving natalizumab plus IFNbeta-1a and increased in those receiving IFNbeta-1a alone (-277.5mm(3) versus 525.6mm(3); p<0.001). Compared with IFNbeta-1a alone, add-on natalizumab therapy resulted in a smaller increase in mean T1-hypointense lesion volume after 2 years (1821.3mm(3) versus 2210.5mm(3); p<0.001), a smaller mean number of new T1-hypointense lesions over 2 years (2.3 versus 4.1; p<0.001), and a slower rate of brain atrophy during the second year of therapy (-0.31% versus -0.40%; p=0.020). Natalizumab add-on therapy reduced gadolinium-enhancing, T1-hypointense, and T2 MRI lesion activity and slowed brain atrophy progression in patients with relapsing MS who experienced disease activity despite treatment with IFNbeta-1a alone.

The efficacy of natalizumab in patients with relapsing multiple sclerosis: subgroup analyses of AFFIRM and SENTINEL.

The AFFIRM and SENTINEL studies showed that natalizumab was effective both as monotherapy and in combination with interferon beta (IFNbeta)-1a in patients with relapsing multiple sclerosis (MS). Further analyses of AFFIRM and SENTINEL data were conducted to determine the efficacy of natalizumab in prespecified patient subgroups according to baseline characteristics: relapse history 1 year before randomization (1, 2, > or = 3), Expanded Disability Status Scale score (< or = 3.5, > 3.5), number of T2 lesions (< 9, > or = 9), presence of gadolinium-enhancing (Gd+) lesions (0, > or = 1), age (< 40, > or = 40) and gender (male, female). A post hoc analysis was conducted to determine the efficacy of natalizumab in patients with highly active disease (i. e., > or = 2 relapses in the year before study entry and > or = 1 Gd+ lesion at study entry). In both AFFIRM and SENTINEL studies natalizumab reduced the annualized relapse rates across all subgroups (except the small subgroups with < 9 baseline T2 lesions) over 2 years. In AFFIRM, natalizumab significantly reduced the risk of sustained disability progression in most subgroups. In SENTINEL, natalizumab significantly reduced the risk of sustained disability progression in the following subgroups: > or = 9 T2 lesions at baseline, > or = 1 Gd+ lesions at baseline, female patients and patients < 40 years of age. Natalizumab reduced the risk of disability progression by 64 % and relapse rate by 81 % in treatment- naive patients with highly active disease and by 58 % and 76 %, respectively, in patients with highly active disease despite IFNbeta-1a treatment. These results indicate that natalizumab is effective in reducing disability progression and relapses in patients with relapsing MS, particularly in patients with highly active disease.

Conditional approval: discussion points from the PSI conditional approval expert group.

The European Agency for the Evaluation of Medicinal Products has recently completed the consultation of a draft guidance on how to implement conditional approval. This route of application is available for orphan drugs, emergency situations and serious debilitating or life-threatening diseases. Although there has been limited experience in implementing conditional approval to date, PSI (Statisticians in the Pharmaceutical Industry) sponsored a meeting of pharmaceutical statisticians with an interest in the area to discuss potential issues. This article outlines the issues raised and resulting discussions, based on the group's interpretation of the legislation. Conditional approval seems to fit well with the accepted regulatory strategy in HIV. In oncology, conditional approval may be most likely when (a) compelling phase II data are available using accepted clinical outcomes (e.g. progression/recurrence-free survival or overall survival) and Phase III has been planned or started, or (b) when data are available using a surrogate endpoint for clinical outcome (e.g. response rate or biochemical measures) from a single-arm study in rare tumours with high response, compared with historical data. The use of interim analyses in Phase III for supporting conditional approval raises some challenging issues regarding dissemination of information, maintenance of blinding, potential introduction of bias, ethics, switching, etc.

Health-related quality of life in multiple sclerosis: effects of natalizumab.

OBJECTIVE: To report the relationship between disease activity and health-related quality of life (HRQoL) in relapsing multiple sclerosis, and the impact of natalizumab. METHODS: HRQoL data were available from 2,113 multiple sclerosis patients in natalizumab clinical studies. In the Natalizumab Safety and Efficacy in Relapsing Remitting Multiple Sclerosis (AFFIRM) study, patients received natalizumab 300 mg (n = 627) or placebo (n = 315); in the Safety and Efficacy of Natalizumab in Combination with Interferon Beta-1a in Patients with Relapsing Remitting Multiple Sclerosis (SENTINEL) study, patients received interferon beta-1a (IFN-beta-1a) plus natalizumab 300 mg (n = 589), or IFN-beta-1a plus placebo (n = 582). The Short Form-36 (SF-36) and a subject global assessment visual analog scale were administered at baseline and weeks 24, 52, and 104. Prespecified analyses included changes from baseline to week 104 in SF-36 and visual analog scale scores. Odds ratios for clinically meaningful improvement or worsening on the SF-36 Physical Component Summary (PCS) and Mental Component Summary were calculated. RESULTS: Mean baseline SF-36 scores were significantly less than the general US population and correlated with Expanded Disability Status Scale scores, sustained disability progression, relapse number, and increased volume of brain magnetic resonance imaging lesions. Natalizumab significantly improved SF-36 PCS and Mental Component Summary scores at week 104 in AFFIRM. PCS changes were significantly improved by week 24 and at all subsequent time points. Natalizumab-treated patients in both studies were more likely to experience clinically important improvement and less likely to experience clinically important deterioration on the SF-36 PCS. The visual analog scale also showed significantly improved HRQoL with natalizumab. INTERPRETATION: HRQoL was impaired in relapsing multiple sclerosis patients, correlated with severity of disease as measured by neurological ratings or magnetic resonance imaging, and improved significantly with natalizumab.

A randomized, placebo-controlled trial of natalizumab for relapsing multiple sclerosis.

BACKGROUND: Natalizumab is the first alpha4 integrin antagonist in a new class of selective adhesion-molecule inhibitors. We report the results of a two-year phase 3 trial of natalizumab in patients with relapsing multiple sclerosis. METHODS: Of a total of 942 patients, 627 were randomly assigned to receive natalizumab (at a dose of 300 mg) and 315 to receive placebo by intravenous infusion every four weeks for more than two years. The primary end points were the rate of clinical relapse at one year and the rate of sustained progression of disability, as measured by the Expanded Disability Status Scale, at two years. RESULTS: Natalizumab reduced the risk of sustained progression of disability by 42 percent over two years (hazard ratio, 0.58; 95 percent confidence interval, 0.43 to 0.77; P<0.001). The cumulative probability of progression (on the basis of Kaplan-Meier analysis) was 17 percent in the natalizumab group and 29 percent in the placebo group. Natalizumab reduced the rate of clinical relapse at one year by 68 percent (P<0.001) and led to an 83 percent reduction in the accumulation of new or enlarging hyperintense lesions, as detected by T2-weighted magnetic resonance imaging (MRI), over two years (mean numbers of lesions, 1.9 with natalizumab and 11.0 with placebo; P<0.001). There were 92 percent fewer lesions (as detected by gadolinium-enhanced MRI) in the natalizumab group than in the placebo group at both one and two years (P<0.001). The adverse events that were significantly more frequent in the natalizumab group than in the placebo group were fatigue (27 percent vs. 21 percent, P=0.048) and allergic reaction (9 percent vs. 4 percent, P=0.012). Hypersensitivity reactions of any kind occurred in 25 patients receiving natalizumab (4 percent), and serious hypersensitivity reactions occurred in 8 patients (1 percent). CONCLUSIONS: Natalizumab reduced the risk of the sustained progression of disability and the rate of clinical relapse in patients with relapsing multiple sclerosis. Adhesion-molecule inhibitors hold promise as an effective treatment for relapsing multiple sclerosis. (ClinicalTrials.gov number, NCT00027300.).

Natalizumab plus interferon beta-1a for relapsing multiple sclerosis.

BACKGROUND: Interferon beta is used to modify the course of relapsing multiple sclerosis. Despite interferon beta therapy, many patients have relapses. Natalizumab, an alpha4 integrin antagonist, appeared to be safe and effective alone and when added to interferon beta-1a in preliminary studies. METHODS: We randomly assigned 1171 patients who, despite interferon beta-1a therapy, had had at least one relapse during the 12-month period before randomization to receive continued interferon beta-1a in combination with 300 mg of natalizumab (589 patients) or placebo (582 patients) intravenously every 4 weeks for up to 116 weeks. The primary end points were the rate of clinical relapse at 1 year and the cumulative probability of disability progression sustained for 12 weeks, as measured by the Expanded Disability Status Scale, at 2 years. RESULTS: Combination therapy resulted in a 24 percent reduction in the relative risk of sustained disability progression (hazard ratio, 0.76; 95 percent confidence interval, 0.61 to 0.96; P=0.02). Kaplan-Meier estimates of the cumulative probability of progression at two years were 23 percent with combination therapy and 29 percent with interferon beta-1a alone. Combination therapy was associated with a lower annualized rate of relapse over a two-year period than was interferon beta-1a alone (0.34 vs. 0.75, P<0.001) and with fewer new or enlarging lesions on T(2)-weighted magnetic resonance imaging (0.9 vs. 5.4, P<0.001). Adverse events associated with combination therapy were anxiety, pharyngitis, sinus congestion, and peripheral edema. Two cases of progressive multifocal leukoencephalopathy, one of which was fatal, were diagnosed in natalizumab-treated patients. CONCLUSIONS: Natalizumab added to interferon beta-1a was significantly more effective than interferon beta-1a alone in patients with relapsing multiple sclerosis. Additional research is needed to elucidate the benefits and risks of this combination treatment. (ClinicalTrials.gov number, NCT00030966.).