A Study of the Safety, Tolerability, Pharmacokinetics, and Immunogenicity of BCX17725

A Phase 1/1b Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Immunogenicity of Single and Multiple Ascending Doses of BCX17725 in Healthy Participants and Multiple Doses of BCX17725 in Participants With Netherton Syndrome

This is a first-in-human, Phase 1/1b, 4-part study that includes the evaluation of safety, tolerability, pharmacokinetics (PK), and immunogenicity of BCX17725 when administered via single and multiple doses in healthy adult participants (Parts 1 and 2), and multiple doses in adult participants with Netherton syndrome (Part 3). In Part 4, the effectiveness, safety, and tolerability of BCX17725 when administered via multiple IV and/or SC doses through 12 weeks will be evaluated in adult and adolescent participants with Netherton syndrome.

Parts 1 and 2 are randomized, placebo-controlled, single-ascending-dose (SAD) and multiple-ascending-dose (MAD) study parts, respectively, in healthy participants. Part 3 will evaluate multiple dose administrations in participants with Netherton syndrome in an open-label design. Part 4 will evaluate multiple administrations of BCX17725 in participants with Netherton syndrome in an open-label study design over 12 weeks, with an 8-week post-treatment follow-up period.

Key Inclusion Criteria:

• Male or non-pregnant, non-lactating female aged 18 to 55 years, inclusive (Parts 1 and 2), 18 to 65 years, inclusive (Part 3), or 12 to 65 years, inclusive (Part 4)
• Confirmed diagnosis of Netherton syndrome (Parts 3 and 4)
• IGA score of ≥ 3 (Parts 3 and 4) and IASI score of ≥ 16 (Part 4)
• BMI between 18 and 30 kg/m^2, inclusive (Parts 1 and 2)
• Estimated glomerular filtration rate (eGFR) of ≥ 90 mL/min/1.73 m^2 (Parts 1 and 2) or ≥ 60 mL/min/1.73 m^2 (Part 3)
• Agree to follow the protocol contraception requirements from screening until 90 days after the last dose of study drug
• In the opinion of the investigator, expected to adequately comply with all required study procedures and restrictions for the duration of the study