Structural characterization of antibody-responses from Zolgensma treatment provides the blueprint for the engineering of an AAV capsid suitable for redosing.

Monoclonal antibodies (mAbs) are useful tools to dissect the neutralizing antibody response against the adeno-associated virus (AAV) capsids used as gene therapy delivery vectors. This study structurally characterizes the interactions of 21 human-derived antibodies from patients treated with the AAV9 vector, Zolgensma ® , utilizing high-resolution cryo-electron microscopy. The majority of the bound antibodies do not conform to the icosahedral symmetry of the capsid, thus requiring localized reconstructions. These complex structures provide unprecedented details of the mAbs binding interfaces, with some antibodies inducing structural perturbations of the capsid upon binding. Key surface capsid amino acid residues were identified facilitating the design of capsid variants with an antibody escape phenotype, with the potential to expand the patient cohort treatable with AAV9 vectors to include those that were previously excluded due to their pre-existing neutralizing antibodies, and possibly also to those requiring redosing.

Real-world effectiveness and safety of ustekinumab for the treatment of Crohn's disease: the Scottish ustekinumab cohort.

BACKGROUND AND AIM: Ustekinumab is a monoclonal antibody that targets interleukin-12/23. In Scotland, it was approved for the treatment of moderate to severe Crohn's disease in 2017. The objective of this study was to establish the real-world effectiveness and safety of ustekinumab in the treatment of Crohn's disease. METHODS: We conducted a retrospective study of patients receiving ustekinumab across eight Scottish National Health Service health boards between 2017 and 2019. Inclusion criteria included a diagnosis of Crohn's disease with symptoms attributed to active disease plus objective signs of inflammation at baseline (C-reactive protein ≥ 5 mg/L or fecal calprotectin ≥ 250 µg/g or inflammation on endoscopy/magnetic resonance imaging) and completion of induction plus at least one clinical follow-up at 8 weeks. Kaplan-Meier survival analysis was used to establish 12-month cumulative rates of clinical remission, mucosal healing, deep remission, and perianal fistula response. Rates of serious adverse events were described quantitatively. RESULTS: Our cohort consisted of 216 patients (female sex, 37.9%; median age, 39.0 years, interquartile range [IQR] 28.8-51.8 years; disease duration, 9.9 years, IQR 6.0-16.5 years; prior biologic, 98.6%) with a median follow-up of 35.0 weeks (IQR 17.4-52.0 weeks). Twelve-month cumulative rates of clinical remission, mucosal healing, and deep remission (clinical remission plus mucosal healing) were 32.0%, 32.7%, and 19.3%, respectively. In patients with active perianal disease (n = 37), the 12-month cumulative perianal response rate was 53.1%. The serious adverse event rate was 13.6 per 100 patient-years of follow-up. CONCLUSION: Ustekinumab is a safe and effective treatment for the treatment of complex Crohn's disease.

Mercaptopurine versus placebo to prevent recurrence of Crohn's disease after surgical resection (TOPPIC): a multicentre, double-blind, randomised controlled trial.

BACKGROUND: Up to 60% of patients with Crohn's disease need intestinal resection within the first 10 years of diagnosis, and postoperative recurrence is common. We investigated whether mercaptopurine can prevent or delay postoperative clinical recurrence of Crohn's disease. METHODS: We did a randomised, placebo-controlled, double-blind trial at 29 UK secondary and tertiary hospitals of patients (aged >16 years in Scotland or >18 years in England and Wales) who had a confirmed diagnosis of Crohn's disease and had undergone intestinal resection. Patients were randomly assigned (1:1) by a computer-generated web-based randomisation system to oral daily mercaptopurine at a dose of 1 mg/kg bodyweight rounded to the nearest 25 mg or placebo; patients with low thiopurine methyltransferase activity received half the normal dose. Patients and their carers and physicians were masked to the treatment allocation. Patients were followed up for 3 years. The primary endpoint was clinical recurrence of Crohn's disease (Crohn's Disease Activity Index >150 plus 100-point increase in score) and the need for anti-inflammatory rescue treatment or primary surgical intervention. Primary and safety analyses were by intention to treat. Subgroup analyses by smoking status, previous thiopurines, previous infliximab or methotrexate, previous surgery, duration of disease, or age at diagnosis were also done. This trial is registered with the International Standard Randomised Controlled Trial Register (ISRCTN89489788) and the European Clinical Trials Database (EudraCT number 2006-005800-15). FINDINGS: Between June 6, 2008, and April 23, 2012, 240 patients with Crohn's disease were randomly assigned: 128 to mercaptopurine and 112 to placebo. All patients received at least one dose of study drug, and no randomly assigned patients were excluded from the analysis. 16 (13%) of patients in the mercaptopurine group versus 26 (23%) patients in the placebo group had a clinical recurrence of Crohn's disease and needed anti-inflammatory rescue treatment or primary surgical intervention (adjusted hazard ratio [HR] 0·54, 95% CI 0·27-1·06; p=0·07; unadjusted HR 0·53, 95% CI 0·28-0·99; p=0·046). In a subgroup analysis, three (10%) of 29 smokers in the mercaptopurine group and 12 (46%) of 26 in the placebo group had a clinical recurrence that needed treatment (HR 0·13, 95% CI 0·04-0·46), compared with 13 (13%) of 99 non-smokers in the mercaptopurine group and 14 (16%) of 86 in the placebo group (0·90, 0·42-1·94; pinteraction=0·018). The effect of mercaptopurine did not significantly differ from placebo for any of the other planned subgroup analyses (previous thiopurines, previous infliximab or methotrexate, previous surgery, duration of disease, or age at diagnosis). The incidence and types of adverse events were similar in the mercaptopurine and placebo groups. One patient on placebo died of ischaemic heart disease. Adverse events caused discontinuation of treatment in 39 (30%) of 128 patients in the mercaptopurine group versus 41 (37%) of 112 in the placebo group. INTERPRETATION: Mercaptopurine is effective in preventing postoperative clinical recurrence of Crohn's disease, but only in patients who are smokers. Thus, in smokers, thiopurine treatment seems to be justified in the postoperative period, although smoking cessation should be strongly encouraged given that smoking increases the risk of recurrence. FUNDING: Medical Research Council.