Evaluation of Topical ATR12-351 in Adults With Netherton Syndrome

Netherton syndrome (NS) is a rare but severe autosomal recessive disease that affects the skin, hair, and immune system. NS presents at birth with red skin covered by fine scales, a specific hair shaft abnormality ("bamboo hair"), atopic lesions, and elevated systemic immunoglobulin E (IgE) levels. Patients often develop allergies and asthma, and the unfortunate prognosis for infants with NS is poor, with 10% mortality in the first 6 months of life and recurrent infections. There are no FDA-approved treatment options for NS. NS is caused by mutations in in the SPINK5 gene encoding the serine protease inhibitor lymphoepithelial Kazal-type related inhibitor (LEKTI). Absence of LEKTI causes unregulated activity of proteases in the kallikrein subfamily, causing excessive desquamation of skin.

ATR12-351 is a topical ointment containing a lyophilized version of a live biotherapeutic product (LBP), Staphylococcus epidermidis (SE) strain designated SE351. This strain has been modified to be auxotrophic and to express recombinant human LEKTI protein (rhLEKTI). ATR12-351 is intended to address the underlying cause of NS by replacing deficient/dysfunctional LEKTI. The treatment consists of applying ATR12-351 to affected areas, where rhLEKTI produced by ATR12-351 will counter the dysregulated skin serine protease activity observed in NS patients.

This first-in-human study is a randomized, double-blind, vehicle-controlled clinical study to assess the safety, tolerability, and pharmacokinetics (PK) of topical ATR12-351 in approximately 12 adult Netherton syndrome patients who will serve as their own control. This study will include a 14-day treatment period to investigate the safety and tolerability of ATR12-351 applied to the skin and will be followed a total of 84 days for safety. The results of this first-in-human clinical study will establish safety and tolerability as well as initial efficacy of ATR12-351 application in Netherton syndrome patients.

Inclusion criteria

• Adults ≥18 years of age
• Confirmed mutation of the serine protease inhibitor of Kazal type 5 (SPINK5) gene
• Involvement of ≥20% of body surface area with skin changes consistent with Netherton syndrome

Exclusion criteria

• Use of biologic therapies, antibiotics, antihistamines, corticosteroids, retinoids, disease-modifying antirheumatic drugs (DMARDs), immunosuppressive agents, phosphodiesterase-4 (PDE4) inhibitors, topical calcineurin inhibitors, or topical Janus kinase (JAK) inhibitors
• Open wounds or extensive areas of excoriation precluding identification of appropriate application sites in the Investigator's judgment
• Concurrent involvement in any other clinical study/expanded access program with an investigational drug or device or has participated in a clinical study within 30 days prior to the screening visit
• Residing with an immunocompromised person in the same dwelling from the baseline visit through 2 weeks after the treatment period
• History of ultraviolet phototherapy within the planned treatment area 4 weeks prior to baseline