Safety, pharmacokinetics and pharmacodynamics of SHR-1703, an innovative long-acting anti-interleukin-5 monoclonal antibody, in healthy subjects: a randomized, double-blind, dose-escalation, placebo-controlled phase I study.

Objective: SHR-1703 is a novel humanized IgG1 monoclonal antibody with high IL-5 affinity and prolonged half-life, aiming to control eosinophil-related diseases. The study intended to evaluate pharmacokinetics, pharmacodynamics, immunogenicity, safety, and tolerability of SHR-1703 in healthy subjects.

Methods: A single-center, randomized, double-blind, placebo-controlled, single-dose escalation phase I study was conducted. 42 subjects were allocated to sequentially receive single subcutaneous injection of 20, 75, 150, 300, and 400 mg SHR-1703 or placebo.

Results: After administration, SHR-1703 was slowly absorbed with median T_max ranging from 8.5 to 24.5 days. Mean t_1/2 in 150 to 400 mg doses was 86 to 100 days. C_max and AUC increased in nearly dose-proportional pattern over range of 75 to 400 mg SHR-1703. After receiving SHR-1703, peripheral blood eosinophils (EOS) greatly decreased from baseline, which showed no significant change from baseline in placebo group. Magnitude and duration of reduction of EOS rose with increased dosing of SHR-1703. In 400 mg dose, remarkable efficacy of reducing EOS maintained up to approximately 6 months post single administration. Moreover, SHR-1703 exhibited low immunogenicity (2.9%), favorable safety, and tolerability in healthy subjects.

Conclusion: Pharmacokinetics, pharmacodynamics, immunogenicity, safety, and tolerability of SHR-1703 support further clinical development of SHR-1703 in eosinophil-associated diseases.

Clinical trial registration: The study was registered on the ClinicalTrials.gov (identifier: NCT04480762).