Ustekinumab (Stelara/Janssen Pharmaceutical) was FDA approved in October 2017 for moderate-to-severe plaque psoriasis in adolescents ages 12 years and older, who are candidates for phototherapy or systemic therapy. Adalimumab (Humira, AbbVie) is another TNF-blocker that has been extensively studied in children, and approved to age 4 in Europe for pediatric psoriasis and in the U.S. to age 6 for Crohns disease and age 2 for juvenile idiopathic arthritis, but lacks specific FDA labelling for pediatric psoriasis, according to Dr. Siegfried.
The safety and efficacy of a few other biologic agents and a small molecule PDE4 inhibitor are currently in clinical trials for pediatric psoriasis down to age 6, she says.
Pediatric psoriasis patients are good candidates for systemic therapy if they have a minimum of 10 percent body surface area involvement, or if their psoriasis is in places that are otherwise hard to treat, including skin folds, scalp or palms and soles.
“Nail psoriasis is another special area. And nail psoriasis can be very severe and debilitating in some children,” she says.
Dr. Siegfried’s first choice for systemic treatment for severe psoriasis in children is methotrexate. She says that 80% of children in a retrospective review of her patients with psoriasis on methotrexate respond well after three months.
“The problem with methotrexate is that it’s a really old drug, so we have less well-established guidelines about optimal dosing. Retrospective analysis has identified obesity and alcohol consumption as the major risk factors for methotrexate-associated hepatic fibrosis in adults. Like adults, obesity is more common in children with psoriasis, but not to the same degree,” Dr. Siegfried said.
“But optimal methotrexate use is tricky. The devil is in the details when managing children in terms of dosing, formulation, route of administration, and helping patients tolerate the drug,” Dr. Siegfried said.
Weighing the risks of methotrexate becomes more important when the lifetime cumulative dose is higher than 2 to 3 grams.
TNF receptor blockers can improve psoriasis, while triggering atopy, including eczema and other atopic comorbidities.
“This is why it is important to identify overlap. I first recognized the condition after treating a child with an anti-TNF agent for chronic inflammatory skin disease that gradually evolved to include recalcitrant palmoplantar involvement. His palms and soles cleared, but his itch and antecubital and popliteal skin lesions flared. Others cases of similar atopic adverse effects have been published,” she says.
There isn’t much data to support her suspicion, but Dr. Siegfried says blocking other inflammatory pathways, such as interleukin-12/23 with the biologic agent ustekinumab, might work for both eczema and psoriasis. Methotrexate seems to work for both.
Biologic dosing in children is weight-based, and regimens differ. Stelara requires an injection every three months while Enbrel is dosed once a week. There’s a lot to consider when choosing the best medication for an individual patient.
For example, Dr. Siegfried has a severely autistic, 300-pound 12-year-old patient with psoriasis. She prescribed Stelara.
“He had thick plaques and severe tactile aversion that restricted practical use of topicals, plus, we wanted to avoid TNF blockers because they can cause weight gain. He has been on ustekinumab for three years and is doing fabulously. It was a miracle treatment for the family," she said.