CHICAGO – Topical gentamicin counters the nonsense mutations that inhibit production of laminin 332 in infants with Herlitz junctional epidermolysis bullosa (H-JEB) to allow lesion healing, according to results of a small clinical study presented at the annual meeting of the Society for Investigative Dermatology.
“All of the children treated so far have responded,” reported Andrew Kwong, who will soon graduate from the Keck School of Medicine at the University of Southern California, Los Angeles.
H-JEB is an inherited blistering skin disease associated with nonsense mutations in the LAMA3, LAMB3, or LAMC2 genes that result in impaired production of functional laminin 332, an essential protein for epidermal-dermal adherence. At this time there are no effective therapies, and the disease is fatal.
The small clinical study was initiated after in vitro studies demonstrated that gentamicin restored functional laminin 332 in cultured keratinocytes from infants with H-JEB. The dose-dependent effect was credited to the ability of gentamicin to induce readthrough of premature stop codons that block production of laminin 332.
Data were presented on the first three infants with H-JEB treated with oral gentamicin. In each child, lesions were treated with topical 0.5% gentamicin twice daily for two weeks. Biopsies were taken prior to the initiation of treatment and at one and three months after treatment. The primary outcome was change in laminin 332, but clinical improvement was also monitored.
Although none of the infants had measurable laminin 332 prior to treatment, all lesions treated with topical gentamicin developed localized laminin 332 at the dermal-epidermal junction of the skin, Mr. Kwong reported. This expression, which was about 40% to 60% of that seen in normal skin, still persisted when evaluated three months after treatment.
The expression was associated with resolution of existing lesions and a reduced risk of developing new lesions, according to Mr. Kwong. In lesions that went untreated, there was no change.
Other molecular changes in the skin, such as increased expression and polarization of beta-4 integrin, were consistent with the ability of gentamicin to address the underlying pathophysiology of H-JEB. There were no adverse events observed.
By restoring functional laminin 332 in the skin, topical gentamicin appears to address the underlying cause of the bullae associated with H-JEB, but Mr. Kwong said that the next step is to determine whether intravenous gentamicin can address the systemic effects. If so, this treatment has the potential to improve survival. He reported that an infant with H-JEB was recently started on intravenous treatment, and initial results were encouraging.
Asked whether he would recommend topical gentamicin on the basis of these findings, Mr. Kwong cautioned that the case series remains very small, but he noted that the uniformity of the positive response is encouraging. He expects that off-label use of this novel and low-cost approach might be warranted in a population that has very limited therapeutic options.
SOURCE: Kwong A. SID 2019;S102, Abstract 594. Annual meeting of the Society for Investigative Dermatology.