24 July 2024
JAK inhibitor helps beat infantile bullous pemphigoid
Chinese dermatologists have detailed their success with treating a six-month-old with the extremely rare skin disorder.
An infant in China with the rare skin disorder infantile bullous pemphigoid has been effectively treated with the JAK inhibitor baricitinib.
In a brief report, published last week in the Australasian Journal of Dermatology, the researchers said this was understood to be the first documented case of an infant with BP being treated with the drug, after steroids and intravenous immunoglobulin failed.
The researchers reported the four-month-old infant was admitted to the Shanghai Jiaotong University School of Medicine Xinhua Hospital’s department of dermatology, with a two-week history of presenting erythematous, flat-topped papules on the ankle, which progressed to a vesicular rash, followed by similar lesions on the upper extremities.
“Initially, the patient was diagnosed with eczema and prescribed topical corticosteroids,” the researchers reported.
“However, the symptoms worsened, and the vesicles progressed to bullae. Upon admission, the patient had erythematous papules and fluid-filled tense blisters on the abdomen and extremities, accompanied by pruritus.”
The infant was subsequently diagnosed with infantile BP, an extremely rare condition.
The annual incidence of BP ranges from six to 13 new cases per one million population per year, the researchers reported. It mainly affects older people, with onset usually in the late 70s, with incidence rising substantially to 150–330 per one million people per year in people older than 80 years.
“However, BP is extremely rare in children and infants and prospective studies are difficult to perform,” the researchers wrote.
“The disease may be life-threatening, particularly when appropriate management is delayed. Baricitinib, through inhibition of the Janus kinase/signal transducer and activator of transcription (JAK–STAT) pathway, demonstrates significant efficacy in treating inflammatory skin diseases, such as atopic dermatitis and alopecia areata.”
Initially the infant was prescribed topical corticosteroids followed by weekly intravenous immunoglobulin for three weeks. However, the disease continued to worsen, and there was minimal improvement in the skin lesions, so they added dupilumab to the treatment.
However, following the initial dose, there was a rapid increase in eosinophil count and the skin lesions did not show improvement, the researchers reported.
Systemic methylprednisolone replaced this therapy for two months, which led to some improvement in existing skin lesions, but did not prevent the appearance of new lesions. Cyclophosphamide was added to the methylprednisolone for a further month, but new lesions persisted.
“Therefore, we contemplated substituting cyclophosphamide with baricitinib to manage the condition and facilitating steroid reduction. Baricitinib (1 mg/day) treatment resulted in no new blister development within one day, gradual disappearance of erythema and normalisation of absolute eosinophil count in one week,” the researchers reported.
“Additionally, the Bullous Pemphigoid Disease Area Index (BPDAI) severity score also returned to normal. After five and a half months of combined use of baricitinib and methylprednisolone, baricitinib was discontinued, followed by a continuation of methylprednisolone alone for four more months before it too was discontinued.
“During the treatment, the patient experienced two mild upper respiratory tract infections but did not encounter any other adverse effects.”
Blood examination results indicated normal absolute counts of immune cells, with the researchers reporting the findings suggested that the treatment did not induce long-term immune suppression in the patient.
“Notably, the patient achieved complete remission and remained recurrence-free during the entire follow-up period,” they wrote.
The researchers conceded that the administration of baricitinib for an infant was rarely reported.
“Using a JAK inhibitor might influence the development of the infant’s immune system and his or her response to infections,” they wrote.
“In our case, the patient tolerated baricitinib well. During follow-up, the patient grew normally and did not present any signs of immune suppression. The patient also received vaccinations and experienced no adverse reactions.”
They cited another reported case, where another JAK inhibitor, ruxolitinib, was used on a child with inherited ubiquitin-specific peptidase 18 (USP18) deficiency for two years. This case was detailed in an article published in the New England Journal of Medicine in 2020, and also showed alleviation of the disease. The patient in that case also showed favourable development and did not report severe adverse effects.
“These findings suggest that baricitinib has an acceptable adverse event profile,” the researchers concluded.
“Further research is needed to support the efficacy and safety of baricitinib in treating infantile BP.”
