ABSTRACT:
QX008N, a humanized IgG1 monoclonal antibody against thymic stromal lymphopoietin (TSLP) with Fc engineering to extend half‐life, was developed with the aim of exploring whether its extended half‐life and cost‐effective production could potentially address unmet needs in severe asthma therapy, such as the need for less frequent dosing and improved accessibility. This first‐in‐human, phase I trial evaluated pharmacokinetics (PK), tolerability, and immunogenicity of QX008N in healthy Chinese subjects following subcutaneous (SC) and intravenous (IV) administration. SC group dosing demonstrated dose‐proportional exposure; for the 280 mg and 560 mg SC doses, AUC₀–∞ values were 37,611 and 81,450 h·μg/mL, respectively, with delayed Tmax (5–8 days) and absolute bioavailability of 62%–67%. Following SC administration, Cmax values were 30.0 μg/mL (280 mg) and 63.9 μg/mL (560 mg), whereas IV administration produced a Cmax of 225.83 μg/mL at 2 h. QX008N exhibited a prolonged half‐life (median 30.4 days (range 25.0–47.1) for the 560 mg SC dose), surpassing tezepelumab's 26 days, supporting potential every 6–8 week dosing. All pharmacokinetic parameters, including terminal elimination half‐life (
t
½), were derived from plasma concentration–time data. Tolerability profiles were favorable: all adverse events were mild/moderate (e.g., self‐resolving rash). No injection‐site reactions were observed following single‐dose administration in healthy subjects. Immunogenicity was low (5.6% ADA incidence; no neutralizing antibodies), with no PK or tolerability impact. Overall, QX008N demonstrated predictable pharmacokinetics, low immunogenicity, and a tolerability profile consistent with single‐dose administration of monoclonal antibodies in healthy subjects. These findings provide foundational PK and tolerability data to support subsequent clinical evaluation in patients.