Placebo response in patients with Dravet syndrome: Post-hoc analysis of two clinical trials.

OBJECTIVE: Dravet syndrome is a rare, early childhood-onset epileptic and developmental encephalopathy. Responses to placebo in clinical trials for epilepsy therapies range widely, but factors influencing placebo response remain poorly understood. This study explored placebo response and its effects on safety, efficacy, and quality of life outcomes in patients with Dravet syndrome. METHODS: We performed exploratory post-hoc analyses of pooled data from placebo-treated patients from the GWPCARE 1B and GWPCARE 2 randomized controlled phase III trials, comparing cannabidiol and matched placebo in 2-18 year old Dravet syndrome patients. All patients had ≥4 convulsive seizures during a baseline period of 4 weeks. RESULTS: 124 Dravet syndrome-treated patients were included in the analysis (2-5 years: n = 35; 6-12 years: n = 52; 13-18 years: n = 37). Convulsive seizures were experienced by all placebo group patients at all timepoints, with decreased median convulsive seizure frequency during the treatment period versus baseline; the number of convulsive seizure-free days was similar to baseline. Convulsive seizure frequency had a nominally significant positive correlation with age and a nominally significant negative correlation with body mass index. Most placebo-treated patients experienced a treatment-emergent adverse event; however, most resolved quickly, and serious adverse events were infrequent. Placebo treatment had very little effect on reported Caregiver Global Impression of Change outcomes versus baseline. INTERPRETATION: Placebo had little impact on convulsive seizure-free days and Caregiver Global Impression of Change versus baseline, suggesting that these metrics may help differentiate placebo and active treatment effects in future studies. However, future research should further assess placebo responses to confirm these results.

Dravet syndrome seizure frequency and clustering: Placebo-treated patients in clinical trials.

OBJECTIVE: Dravet syndrome is a rare developmental epilepsy syndrome associated with severe, treatment-resistant seizures. Since seizures and seizure clusters are linked to morbidity, reduced quality of life, and premature mortality, a greater understanding of these outcomes could improve trial designs. This analysis explored seizure types, seizure clusters, and factors affecting seizure cluster variability in Dravet syndrome patients. METHODS: Pooled post-hoc analyses were performed on data from placebo-treated patients in GWPCARE 1B and GWPCARE 2 randomized controlled phase III trials comparing cannabidiol and placebo in Dravet syndrome patients aged 2-18 years. Multivariate stepwise analysis of covariance of log-transformed convulsive seizure cluster frequency was performed, body weight and body mass index z-scores were calculated, and incidence of adverse events was assessed. Data were summarized in three age groups. RESULTS: We analyzed 124 placebo-treated patients across both studies (2-5 years: n = 35; 6-12 years: n = 52; 13-18 years: n = 37). Generalized tonic-clonic seizures followed by myoclonic seizures were the most frequent seizure types. Mean and median convulsive seizure cluster frequency overall decreased between baseline and maintenance period but did not change significantly during the latter; variation in convulsive seizure cluster frequency was observed across age groups. Multivariate analysis suggested correlations between convulsive seizure cluster frequency and age (positive), and body mass index (BMI) (negative). INTERPRETATION: Post-hoc analyses suggested that potential relationships could exist between BMI, age and convulsive seizure cluster variation. Results suggested that seizure cluster frequency may be a valuable outcome in future trials. Further research is needed to confirm our findings.

Retrospective chart review study of use of cannabidiol (CBD) independent of concomitant clobazam use in patients with Lennox-Gastaut syndrome or Dravet syndrome.

PURPOSE: This retrospective chart review study (GWEP20052) evaluated plant-derived highly purified cannabidiol (CBD; Epidyolex®; 100 mg/mL oral solution) use without clobazam as add-on therapy in patients aged ≥2 years with Lennox-Gastaut syndrome (LGS) or Dravet syndrome (DS) enrolled in a European Early Access Program. METHODS: Data were extracted from patient charts covering a period starting 3 months before CBD treatment and concluding after 12 months of CBD treatment, or sooner if a patient discontinued CBD or started clobazam. RESULTS: Of 114 enrolled patients, data were available for 107 (92 LGS, 15 DS) who received CBD without clobazam for ≥3 months. Mean age: 14.5 (LGS) and 10.5 (DS) years; female: 44% (LGS) and 67% (DS). Mean time-averaged CBD dose: 13.54 (LGS) and 11.56 (DS) mg/kg/day. Median change from baseline in seizure frequency per 28 days over 3-month intervals varied from -6.2% to -20.9% for LGS and 0% to -16.7% for DS. Achievement of ≥50% reduction in drop (LGS) or convulsive (DS) seizures at 3 and 12 months: LGS, 19% (n = 69) and 30% (n = 53); DS, 21% (n = 14) and 13% (n = 8). Retention on CBD without clobazam (enrolled set): 94%, 80%, 69%, and 63% at 3, 6, 9, and 12 months. Adverse event (AE) incidence was 31%, most commonly somnolence, seizure, diarrhea, and decreased appetite. Two patients discontinued CBD owing to AEs, and four patients with LGS experienced elevated liver enzymes. CONCLUSION: Results support favorable effectiveness and retention of CBD without concomitant clobazam for up to 12 months in clinical practice.

Seizure-free days as a novel outcome in patients with Lennox-Gastaut syndrome: Post hoc analysis of patients receiving cannabidiol in two randomized controlled trials.

OBJECTIVE: In this post hoc analysis, we aimed to assess seizure-free days as a potential new outcome measure to use in randomized placebo-controlled trials (RCTs) of patients with Lennox-Gastaut syndrome (LGS). METHODS: In two phase 3 RCTs (GWPCARE3, GWPCARE4), eligible patients were randomized to receive plant-derived highly purified cannabidiol (CBD; Epidiolex® in the USA; 100 mg/mL oral solution) at 10 mg/kg/day (CBD10; GWPCARE3 only), at 20 mg/kg/day (CBD20), or matched placebo. The treatment period comprised a 2-week dose titration and a 12-week maintenance period. This post hoc analysis evaluated the least-squares (LS) mean changes from baseline and difference versus placebo in the number of drop or total seizure-free days per 28 days during the treatment period or maintenance period alone. LS mean changes were estimated using an analysis of covariance model, with categorical age and baseline number of drop or total seizure-free days as covariates, and treatment group as a fixed factor. RESULTS: A total of 396 patients were included in this post hoc analysis. During the 14-week treatment period, LS mean changes from baseline in number of drop seizure-free days per 28 days for patients receiving placebo (n = 161), CBD10 (n = 73), and CBD20 (n = 162) were 2.81 (95% confidence interval [CI] = 1.75-3.88), 5.64 (95% CI = 4.08-7.20), and 6.45 (95% CI = 5.39-7.52), respectively. The LS mean differences in number of drop seizure-free days versus placebo were 2.83 (95% CI = .98-4.68) for CBD10 and 3.64 (95% CI = 2.18-5.10) for CBD20. For total seizure-free days, LS mean differences versus placebo were 2.63 (95% CI = .92-4.34) for CBD10 and 3.50 (95% CI = 2.16-4.85) for CBD20. The improvements from baseline in seizure-free days during the maintenance period alone were similar to the entire treatment period. SIGNIFICANCE: Drop and total seizure-free days represent potential new and clinically meaningful endpoints for future RCTs in patients with LGS.

Treatment Guidelines for Rare, Early-Onset, Treatment-Resistant Epileptic Conditions: A Literature Review on Dravet Syndrome, Lennox-Gastaut Syndrome and CDKL5 Deficiency Disorder.

Background: Dravet syndrome (DS), Lennox-Gastaut syndrome (LGS) and CDKL5 deficiency disorder (CDD) are rare epileptic conditions, characterised by drug-resistant seizures. Seizure management in these patients requires careful therapy selection. This targeted literature review (TLR) aimed to collate and synthesise information from country-specific and international treatment guidelines for DS, LGS and CDD. Methods: A TLR was performed between 25th January and 11th March 2021. Online rare diseases and guideline databases were manually searched in addition to websites of national health technology assessment bodies for the following countries: Australia, Canada, France, Germany, Israel, Italy, Japan, Spain, Switzerland, UK and US, as defined by pre-specified eligibility criteria. Search terms, developed for each condition, were translated into local languages where appropriate. Descriptive analyses were performed to examine the geographical distribution of included guidelines; methodologies used to develop guidelines; cross-referencing of treatment recommendations made within other guidelines; patterns of treatment recommendations. An author map was created using R version 3.5.1, to visualise the extent of collaboration between authors. Results: Forty total guidelines were included, of which 29, 34 and 0 contained recommendations for DS, LGS and CDD, respectively (some provided recommendations for ≥1 condition). Most were country-specific, with guideline authors predominantly publishing in regional groups. Five guidelines were classified as "International" and displayed connections between author groups in the US, UK, France and Italy. Reported guideline development processes were lacking [43% (17 guidelines) had unclear/absent literature review methodologies] and those reported were variable, including both systematic and targeted literature reviews. Use of expert consultation was also variable. A high degree of heterogeneity was observed in the availability of treatment recommendations across disorders, with 271 and 190 recommendations for LGS and DS, respectively, and contradictory positive and negative treatment recommendations for several drugs in each indication [35% (11/31) and 22% (6/27) in LGS and DS, respectively]. Conclusions: This review highlights the need for further high-quality international consensus-based treatment guidelines for LGS, DS, and particularly for CDD (for which no treatment guidelines were identified). Supra-national consensus guidance based on findings from a wider geographical range may improve resource allocation and establish an improved world-wide standard of care.

Cannabidiol in conjunction with clobazam: analysis of four randomized controlled trials.

OBJECTIVES: To assess the efficacy and safety profile of add-on cannabidiol (CBD) in patients with Lennox-Gastaut syndrome (LGS) and Dravet syndrome (DS) on clobazam and in the overall population of four randomized, controlled phase 3 trials. METHODS: Patients received plant-derived, highly purified CBD medicine (Epidiolex® in the USA; Epidyolex® in Europe; 100 mg/ml oral solution) at a dose of 10 or 20 mg/kg/day, or placebo for 14 weeks. A subgroup analysis of patients on clobazam and meta-analysis by syndrome were conducted. The primary endpoint was percentage reduction in primary seizure type during the treatment period. RESULTS: 396 patients with LGS (49% on clobazam) and 318 patients with DS (64% on clobazam) were included. CBD treatment resulted in a reduction in primary seizure frequency vs placebo in the overall population (treatment ratio [95% confidence interval]: LGS, 0.70 [0.62-0.80]; DS, 0.71 [0.60-0.83]) and in patients receiving clobazam (LGS, 0.56 [0.47-0.67]; DS, 0.63 [0.52-0.77]). The antiseizure efficacy of CBD was also demonstrated across other endpoints vs placebo (≥50% responder rate, total seizure frequency, number of seizure-free days, and Subject/Caregiver Global Impression of Change scores) in the overall populations and in patients receiving clobazam. There were higher incidences of somnolence and sedation in patients on CBD and clobazam. Most incidences of elevated transaminases occurred in patients on concomitant valproate and, to a lesser extent, clobazam. CONCLUSIONS: Add-on CBD was effective in reducing seizures in the overall populations and in conjunction with clobazam. Somnolence and sedation occurred more frequently in patients on CBD and clobazam.