Ustekinumab for the Treatment of Moderate-to-severe Plaque Psoriasis in Paediatric Patients (≥ 6 to < 12 Years of Age): Efficacy, Safety, Pharmacokinetic and Biomarker Results from the Open-label CADMUS Jr Study

Background: Limited options are available for treatment of paediatric psoriasis.

Objectives: To evaluate the efficacy and safety of ustekinumab in paediatric patients with psoriasis (≥ 6 to < 12 years of age).

Methods: CADMUS Jr, a phase III, open-label, single-arm, multicentre study, evaluated ustekinumab in paediatric patients with moderate-to-severe plaque psoriasis. Patients received weight-based dosing of ustekinumab (< 60 kg: 0·75 mg kg ; ≥ 60 to ≤ 100 kg: 45 mg; > 100 kg: 90 mg) administered by subcutaneous injection at weeks 0 and 4, then every 12 weeks through week 40. Study endpoints (all at week 12) included the proportions of patients achieving a Physician's Global Assessment score of cleared/minimal (PGA 0/1) and ≥ 75%/90% improvement in Psoriasis Area and Severity Index (PASI 75/90), and change in Children's Dermatology Life Quality Index (CDLQI). Serum ustekinumab concentrations, antidrug antibodies and cytokine levels were measured through week 52. Safety was evaluated through week 56.

Results: In total, 44 patients (median age 9·5 years) received at least one dose of ustekinumab. Three patients discontinued the study agent through week 40. At week 12, 77% of patients achieved PGA 0/1, 84% achieved PASI 75 and 64% achieved PASI 90 response. The mean change in CDLQI was -6·3. Trough serum ustekinumab concentrations reached steady state at weeks 28-52. The incidence of antidrug antibodies was 10% (n = 4). Mean serum concentrations of interleukin-17A/F and interleukin-22 were significantly reduced at weeks 12 and 52. Overall, 34 patients (77%) had at least one adverse event and three (7%) had a serious adverse event.

Conclusions: Ustekinumab effectively treated moderate-to-severe psoriasis in paediatric patients, and no new safety concerns were identified. What is already known about this topic? Ustekinumab is approved for use in adolescents (≥ 12 to < 18 years of age) and adults (≥ 18 years) with moderate-to-severe psoriasis. What does this study add? Ustekinumab effectively treats moderate-to-severe psoriasis in paediatric patients (≥ 6 to < 12 years of age), with no new safety concerns. Linked Comment: Reich. Br J Dermatol 2020; 183:606-607.