BERLIN – as previously shown in adolescents and adults for whom it already has an approved indication.
In this study – TRUE-AD3 – systemic exposure to ruxolitinib, which is selective for JAK1 and 2, was followed closely, and the low mean plasma concentrations “suggest systemic JAK inhibition is highly unlikely,” Lawrence F. Eichenfield, MD, professor of dermatology and pediatrics at the University of California, San Diego, said at the annual congress of the European Academy of Dermatology and Venereology.
Ted Bosworth/MDedge News
Dr. Lawrence F. Eichenfield
For example, at a plasma concentration no greater than 27 nM in both younger and older patients at 4 weeks and again at 8 weeks, the systemic exposure was about a tenth of that (281 nM) previously associated with myelosuppression, he reported.
Given the boxed warning for oral JAK inhibitors, which was based largely on a 2022 study in adults with rheumatoid arthritis that associated tofacitinib, a nonspecific JAK inhibitor, with an increased risk of thrombotic events in adults already at risk for these events, safety was a focus of this phase 3 trial. The boxed warning is also in the labeling for topical ruxolitinib, 1.5% (Opzelura), approved for treating to mild to moderate atopic dermatitis in patients 12 years of age and older.
Dr. Eichenfield said there were no significant safety signals in the younger pediatric population. “There were no treatment-emergent adverse events suggestive of systemic JAK inhibition,” he said. This not only included the absence of serious infections, cardiac events, thromboses, or malignancies, but there was no signal of hematologic abnormalities, such as change in hemoglobin or neutrophil count.
Application site reactions
Rather, in the study of children ages 2-11, the only adverse events associated with topical ruxolitinib not observed in the control arm, which received the vehicle alone, were application site reactions, such as pain, erythema, and irritation. None of these occurred in more than 3% of those randomized to ruxolitinib regardless of dose.
Overall, in the trial, which randomized 329 patients ages from 2 to under 12 years with mild to moderate AD to ruxolitinib 1.5% cream, ruxolitinib 0.75% cream, or vehicle in a 2:2:1 fashion, there were just two (0.8%) discontinuations in the ruxolitinib groups (one in each dosing arm). There were none in the vehicle arm.
The safety supports an expansion of the AD indication for topical ruxolitinib in young children, because the rates of response were very similar to that seen in adolescents and adults in the previously published TRUE AD-1 and TRUE AD-2 trials, he said.
For the primary endpoint of Investigator’s Global Assessment (IGA) score of 0 (clear) or 1 (almost clear) with at least a 2 grade improvement in IGA score from baseline, the response rates were 56.5%, 36.6%, and 10.8% for ruxolitinib 1.5%, ruxolitinib 0.75%, and vehicle respectively, at 8 weeks (P < .0001 for both doses relative to vehicle).
For the secondary efficacy endpoint of 75% or greater clearance on the Eczema Area and Severity Index, the rates were 67.2%, 51.5%, and 15.4%, for ruxolitinib 1.5%, ruxolitinib 0.75%, and vehicle respectively. Again, the advantage of both doses of ruxolitinib relative to vehicle was highly statistically significant (P < .0001).
Control of itch, evaluated with the Numerical Rating Scale was only evaluated in children 6-2 because of concern of the reliability of reporting in younger children. Control was defined as at least a 4-point improvement from baseline. It was achieved by 43.4%, 37.5%, and 29.7% by week 8 in the arms receiving the higher dose of ruxolitinib, the lower dose, and vehicle, respectively. The median time to achieving itch control was 11 days, 13 days, and 23 days, respectively. For all of these endpoints, the separation of the curves was readily apparent within the first 2 weeks.
The efficacy and tolerability of ruxolitinib appeared to be similar in younger children (ages 2-6) relative to older children.