The use of everolimus in the treatment of neurocognitive problems in tuberous sclerosis (TRON): study protocol for a randomised controlled trial

Abstract

Background: Tuberous sclerosis complex (TSC) is a genetic disorder affecting about 1 in 6000 people and is characterised by the development of tumours in many organs, including the skin and kidneys, and by a range of neurological and neuropsychiatric manifestations. TSC-associated neuropsychiatric disorders (TAND) occur in the majority of those with TSC, and they have a significant impact on patients and their families, given the everyday impact of TAND on education, employment, family and social life. The potential benefits of better treatment for TAND therefore include reduction in health care demands and wider benefits for patients and their carers.

Methods/design: We have planned a single-centre, two-arm, individually randomised, phase II, double-blind, placebo-controlled trial of everolimus versus placebo in the treatment of neurocognitive problems in patients with tuberous sclerosis. Everolimus is a licensed medicine in this patient group, but for a different target of effect. The present trial is a proof-of-principle study developed to provide effect size estimates which may be used to inform the design of subsequent trials. Forty-eight patients aged 16-60 years with tuberous sclerosis who have an IQ >60 and a significant deficit (at least -2 SD) in one or more primary outcome measures will be randomly allocated in a ratio of 2:1 to receive everolimus or placebo, respectively. Participants will be assessed for eligibility and then be started on study medication 4 weeks later. They will then be randomised and receive placebo or everolimus for 24 weeks. Neurocognitive and safety assessments will be carried out at baseline and weeks 4, 12, 24 and 36.

Discussion: This study is designed to determine the effect sizes of treatment with everolimus or placebo for 6 months on specific neurocognitive functions-recall memory (verbal and non-verbal) and executive function-in people affected by TSC who have significant deficits in these functions. These data will provide new evidence to determine whether larger-scale trials are indicated and to explore suitable outcome measures and analytical methods for neurocognitive trial design.

Trial registration: ISRCTN09739757 . Registered on 28 Dec 2011.

Keywords: Epilepsy; Everolimus; Neurocognitive; Randomised controlled trial; TSC; Tuberous sclerosis.

Fig. 1

TRON trial design flowchart indicating anticipated patient numbers and dropout. CRN Clinical Research Network, DTI MR diffusion tensor imaging magnetic resonance imaging, PIS patient information sheet, TSA Tuberous Sclerosis Association