Biologic Therapy in Pediatric Hidradenitis Suppurativa: New Approvals, New Questions

Nearly half of all patients with hidradenitis suppurativa (HS) report their onset of disease in childhood.¹ For many years, treatment options for pediatric HS have lagged behind those available for adults. Although disease onset commonly occurs during adolescence, clinicians often hesitate to escalate therapy in younger patients because of limited pediatric safety data and a lack of approved medications.² As a result, children and adolescents with HS may experience years of uncontrolled inflammation before receiving effective treatment, allowing irreversible tunnel formation during a critical period of physical and psychosocial development.³

Why Early Treatment Matters
HS is no longer viewed as a condition that should simply be managed until patients become adults. Growing evidence supports a “window of opportunity” during which controlling inflammation before extensive scarring develops may improve long-term outcomes.⁴ Delays in diagnosis remain common, and delays in treatment escalation can be just as detrimental. While clinicians may feel more cautious prescribing systemic therapies in adolescents, persistent inflammatory nodules, abscesses, recurrent drainage, or early scarring should prompt consideration of advanced therapy regardless of patient age.

Disease severity should also be viewed beyond Hurley staging alone. Adolescents with Hurley stage I disease may still experience frequent painful flares, school absenteeism, impaired quality of life, and substantial psychosocial distress.³ For many patients, the burden of disease is far greater than their physical examination alone.

Two FDA-Approved Biologics for Pediatric HS
As with adults, biologic therapy should generally be considered for patients with moderate-to-severe disease or disease that remains active despite appropriate trials of other interventions. Importantly, biologics should not be viewed as a treatment of last resort after years of uncontrolled disease.⁵

In 2018, adalimumab became the only biologic approved by the US Food and Drug Administration (FDA) for adolescents ages 12 years and older with moderate-to-severe HS. More recently, secukinumab became the second FDA-approved biologic for adolescents with HS, providing clinicians with an additional therapeutic mechanism through inhibition of IL-17A. Having 2 FDA-approved biologic classes gives clinicians greater flexibility when selecting therapy and provides another option for patients who have an inadequate response or those who cannot tolerate tumor necrosis factor inhibition.

Understanding Pediatric Dosing for HS
Although we have 2 FDA-approved therapies for pediatric HS, there have been no completed phase 3 studies of any drugs for this indication. Rather than conducting large pediatric efficacy trials, pharmaceutical companies have used model-informed drug development (MIDD) to determine dosing recommendations.⁶

MIDD combines pharmacokinetic modeling and computer simulations to identify pediatric doses that achieve drug exposures shown to be effective in adults. The models leverage existing adult clinical trial data and existing pharmacokinetic data on these drugs for other pediatric indications. This approach can reduce the number of children needed for clinical studies, accelerate access to new therapies, and minimize unnecessary research exposure in rare diseases. It is important to note that unlike adalimumab, secukinumab’s dosing differs substantially from adults. Children must weigh at least 90 kg to be eligible for 300-mg dosing, and the option to increase to every 2 weeks due to inadequate clinical response does not exist. For example, while an 18-year-old patient weighing 60 kg could receive 300 mg every 2 weeks, that same patient at age 17 could not go above 150 mg every 4 weeks on label.

Clinicians should recognize the limitations of this approach. Equivalent drug exposure does not necessarily guarantee equivalent clinical response. Puberty, body composition, obesity, immune maturation, and developmental differences may all influence pharmacodynamics in ways that are difficult to model.⁷ Longterm real-world studies will be important to determine whether modeled dosing translates into sustained clinical benefit across diverse pediatric populations.

What Is Next?
The pipeline for pediatric HS continues to grow. Drug companies and the FDA have begun to recognize that pediatric HS is not necessarily a rare disease. As a result, several newer therapies are being evaluated in phase 3 trials in adolescents, sometimes alongside adults for initial approval. These include therapies that target IL-17 (bimekizumab, sonelokimab), IL-1 (lutikizumab), Janus kinase 1 and 2 (povorcitinib, upadacitinib, and topical ruxolitinib), and Bruton tyrosine kinase (remibrutinib). The increasing number of pediatric clinical trials reflects a welcome shift toward studying children and adolescents directly instead of depending on extrapolation from adult disease.

Looking Ahead
With 2 biologic therapies now approved for adolescents with HS and several additional agents under investigation, dermatologists have more opportunities than ever to intervene earlier in the disease course. This shift has the potential to improve disease control and reduce the lifelong burden of this chronic disease.