A new US patent covering an engineered live biotherapeutic for Netherton syndrome was awarded to Connecticut-based Azitra, Inc. (NYSE American: AZTR). As per the company press release, the firm received US Patent No. 12,606,610 B2 from the USPTO on April 21, 2026, covering compositions and methods for treating Netherton syndrome using LEKTI-expressing recombinant microbes. The Azitra ATR-12 patent covers microbes that secrete one or more domains of the lympho-epithelial Kazal-type-related inhibitor (LEKTI) protein and the methods of using those microbes to treat skin diseases, providing both composition-of-matter and method-of-treatment protection for the program.
Scientific basis and mechanism of the ATR-12 program
Netherton syndrome is caused by loss-of-function mutations in the SPINK5 gene, which encodes LEKTI, a serine protease inhibitor expressed in epithelial tissues. In the absence of functional LEKTI, unchecked serine protease activity in the skin leads to degradation of the cornified cell envelope, barrier dysfunction, chronic inflammation, and susceptibility to infection. The condition is estimated to affect approximately 20,000 patients globally, can be fatal in infancy, and carries profound lifelong morbidity for those who survive beyond early childhood. No therapy has received regulatory approval for the indication.
ATR-12 addresses the underlying protein deficiency through a microbiome-based delivery strategy. The asset uses an engineered strain of Staphylococcus epidermidis, a commensal bacterium naturally resident on human skin, that has been genetically modified to express and secrete a fragment of the human LEKTI protein. When applied topically, the engineered strain is designed to colonize the skin surface and provide local, sustained delivery of the missing protease inhibitor directly at the site of pathology. The approach bypasses the need for systemic drug exposure and leverages the skin’s existing microbial ecology as a therapeutic delivery vehicle.
The patent title, “Compositions and Methods for Treatment of Netherton Syndrome with LEKTI Expressing Recombinant Microbes,” reflects the dual scope of protection: the engineered S. epidermidis strain itself as a composition, and the therapeutic use of LEKTI-expressing microbes to treat skin diseases including Netherton syndrome. The breadth of the claims, as described by the company, extends to microbes secreting one or more LEKTI domains, which may provide coverage beyond the specific ATR-12 construct.
The ATR-12 program is currently being evaluated in a Phase I b clinical trial in adult patients with Netherton syndrome.
Context and competitive landscape
The issuance of the Azitra ATR-12 patent reflects a broader shift in dermatology drug development toward microbiome-based and precision delivery platforms, particularly for rare monogenic skin diseases where conventional small-molecule and biologic approaches have not produced approved therapies.