Large multicenter randomized trials in autism: key insights gained from the balovaptan clinical development program.

BACKGROUND: Autism spectrum disorder (ASD) is a common and heterogeneous neurodevelopmental condition that is characterized by the core symptoms of social communication difficulties and restricted and repetitive behaviors. At present, there is an unmet medical need for therapies to ameliorate these core symptoms in order to improve quality of life of autistic individuals. However, several challenges are currently faced by the ASD community relating to the development of pharmacotherapies, namely in the conduct of clinical trials. Balovaptan is a V1a receptor antagonist that has been investigated to improve social communication difficulties in individuals with ASD. In this viewpoint, we draw upon our recent first-hand experiences of the balovaptan clinical development program to describe current challenges of ASD trials. DISCUSSION POINTS: The balovaptan trials were conducted in a wide age range of individuals with ASD with the added complexities associated with international trials. When summarizing all three randomized trials of balovaptan, a placebo response was observed across several outcome measures. Placebo response was predicted by greater baseline symptom severity, online recruitment of participants, and less experienced or non-academic trial sites. We also highlight challenges relating to selection of outcome measures in ASD, the impact of baseline characteristics, and the role of expectation bias in influencing trial results. CONCLUSION: Taken together, the balovaptan clinical development program has advanced our understanding of the key challenges facing ASD treatment research. The insights gained can be used to inform and improve the design of future clinical trials with the collective aim of developing efficacious therapies to support individuals with ASD.

Efficacy and safety of balovaptan for socialisation and communication difficulties in autistic adults in North America and Europe: a phase 3, randomised, placebo-controlled trial.

BACKGROUND: There are no approved pharmacological therapies to support treatment of the core communication and socialisation difficulties associated with autism spectrum disorder in adults. We aimed to assess the efficacy, safety, and pharmacokinetics of balovaptan, a vasopressin 1a receptor antagonist, versus placebo in autistic adults. METHODS: V1aduct was a phase 3, randomised, placebo-controlled, double-blind trial, conducted at 46 sites across six countries (the USA, the UK, France, Italy, Spain, and Canada). Eligible participants were aged 18 years or older with an intelligence quotient (IQ) of 70 or higher, and met the criteria for moderate-to-severe autism spectrum disorder (DSM-5 and Autism Diagnostic Observation Schedule). Participants were randomly allocated (1:1), with an independent interactive voice or web-based response system, to receive balovaptan (10 mg) or placebo daily for 24 weeks. Randomisation was stratified by an individual's baseline Vineland-II two-domain composite (2DC) score (<60 or ≥60), sex, region (North America or rest of world), and age (<25 years or ≥25 years). Participants, study site personnel, and the sponsor were masked to treatment assignment. The primary endpoint was change from baseline in Vineland-II 2DC score (the mean composite score across the Vineland-II socialisation and communication domains) at week 24. The primary analysis was done with ANCOVA in the intention-to-treat population. The V1aduct study was terminated for futility after around 50% of participants completed the week 24 visit. This trial is registered with ClinicalTrials.gov (NCT03504917). FINDINGS: Between Aug 8, 2018, and July 1, 2020, 540 people were screened for eligibility, of whom 322 were allocated to receive balovaptan (164 [51%]) or placebo (158 [49%]). One participant from the balovaptan group was not treated before trial termination and was excluded from the analysis. 60 participants in the balovaptan group and 55 in the placebo group discontinued treatment before week 24. The sample consisted of 64 (20%) women and 257 (80%) men, with 260 (81%) participants from North America and 61 (19%) from Europe. At baseline, mean age was 27·6 years (SD 9·7) and mean IQ score was 104·8 (18·1). Two (1%) participants were American Indian or Alaska Native, eight (2%) were Asian, 15 (5%) were Black or African American, 283 (88%) were White, four (1%) were of multiple races, and nine (3%) were of unknown race. Mean baseline Vineland-II 2DC scores were 67·2 (SD 15·3) in the balovaptan group and 66·2 (17·7) in the placebo group. The interim futility analysis showed no improvement for balovaptan versus placebo in terms of Vineland-II 2DC score at week 24 compared with baseline, with a least-squares mean change of 2·91 (SE 1·52) in the balovaptan group (n=79) and 4·75 (1·60) in the placebo group (n=71; estimated treatment difference -1·84 [95% CI -5·15 to 1·48]). In the final analysis, mean change from baseline in Vineland-II 2DC score at week 24 was 4·56 (SD 10·85) in the balovaptan group (n=111) and 6·83 (12·18) in the placebo group (n=99). Balovaptan was well tolerated, with similar proportions of participants with at least one adverse event in the balovaptan group (98 [60%] of 163) and placebo group (104 [66%] of 158). The most common adverse events were nasopharyngitis (14 [9%] in the balovaptan group and 19 [12%] in the placebo group), diarrhoea (11 [7%] and 14 [9%]), upper respiratory tract infection (ten [6%] and nine [6%]), insomnia (five [3%] and eight [5%]), oropharyngeal pain (five [3%] and eight [5%]), and dizziness (two [1%] and ten [6%]). Serious adverse events were reported for two (1%) participants in the balovaptan group (one each of suicidal ideation and schizoaffective disorder), and five (3%) participants in the placebo group (one each of suicidal ideation, panic disorder, limb abscess, urosepsis, colitis [in the same participant with urosepsis], and death by suicide). No treatment-related deaths occurred. INTERPRETATION: Balovaptan did not improve social communication in autistic adults. This study provides insights into challenges facing autism spectrum disorder trials, including the considerable placebo response and the selection of appropriate outcome measures. FUNDING: F Hoffmann-La Roche.

Correction to: A phase III randomized trial of gantenerumab in prodromal Alzheimer's disease.

Following publication of the original article [1], the author reported errors in the formatting of the table. The details of the errors are as follows.

A phase III randomized trial of gantenerumab in prodromal Alzheimer's disease.

BACKGROUND: Gantenerumab is a fully human monoclonal antibody that binds aggregated amyloid-ß (Aß) and removes Aß plaques by Fc receptor-mediated phagocytosis. In the SCarlet RoAD trial, we assessed the efficacy and safety of gantenerumab in prodromal Alzheimer's disease (AD). METHODS: In this randomized, double-blind, placebo-controlled phase III study, we investigated gantenerumab over 2 years. Patients were randomized to gantenerumab 105 mg or 225 mg or placebo every 4 weeks by subcutaneous injection. The primary endpoint was the change from baseline to week 104 in Clinical Dementia Rating Sum of Boxes (CDR-SB) score. We evaluated treatment effects on cerebrospinal fluid biomarkers (all patients) and amyloid positron emission tomography (substudy). A futility analysis was performed once 50% of patients completed 2 years of treatment. Safety was assessed in patients who received at least one dose. RESULTS: Of the 3089 patients screened, 797 were randomized. The study was halted early for futility; dosing was discontinued; and the study was unblinded. No differences between groups in the primary (least squares mean [95% CI] CDR-SB change from baseline 1.60 [1.28, 1.91], 1.69 [1.37, 2.01], and 1.73 [1.42, 2.04] for placebo, gantenerumab 105 mg, and gantenerumab 225 mg, respectively) or secondary clinical endpoints were observed. The incidence of generally asymptomatic amyloid-related imaging abnormalities increased in a dose- and APOE ε4 genotype-dependent manner. Exploratory analyses suggested a dose-dependent drug effect on clinical and biomarker endpoints. CONCLUSIONS: The study was stopped early for futility, but dose-dependent effects observed in exploratory analyses on select clinical and biomarker endpoints suggest that higher dosing with gantenerumab may be necessary to achieve clinical efficacy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01224106 . Registered on October 14, 2010.

Mechanism of amyloid removal in patients with Alzheimer disease treated with gantenerumab.

BACKGROUND: Gantenerumab is a fully human anti-Aß monoclonal antibody in clinical development for the treatment of Alzheimer disease (AD). OBJECTIVES: To investigate whether treatment with gantenerumab leads to a measurable reduction in the level of Aß amyloid in the brain and to elucidate the mechanism of amyloid reduction. DESIGN: A multicenter, randomized, double-blind, placebo-controlled, ascending-dose positron emission tomographic study. Additionally, ex vivo studies of human brain slices from an independent sample of patients who had AD were performed. SETTING: Three university medical centers. PATIENTS: Patients with mild-to-moderate AD. INTERVENTION: Two consecutive cohorts of patients received 2 to 7 infusions of intravenous gantenerumab (60 or 200 mg) or placebo every 4 weeks. Brain slices from patients who had AD were coincubated with gantenerumab at increasing concentrations and with human microglial cells. MAIN OUTCOME MEASURES: Percent change in the ratio of regional carbon 11-labeled Pittsburgh Compound B retention in vivo and semiquantitative assessment of gantenerumab-induced phagocytosis ex vivo. RESULTS: Sixteen patients with end-of-treatment positron emission tomographic scans were included in the analysis. The mean (95% CI) percent change from baseline difference relative to placebo (n = 4) in cortical brain amyloid level was -15.6% (95% CI, -42.7 to 11.6) for the 60-mg group (n = 6) and -35.7% (95% CI, -63.5 to -7.9) for the 200-mg group (n = 6). Two patients in the 200-mg group showed transient and focal areas of inflammation or vasogenic edema on magnetic resonance imaging scans at sites with the highest level of amyloid reduction. Gantenerumab induced phagocytosis of human amyloid in a dose-dependent manner ex vivo. CONCLUSION: Gantenerumab treatment resulted in a dose-dependent reduction in brain amyloid level, possibly through an effector cell-mediated mechanism of action.