This phase Ia study is meant to evaluate the tolerability, safety, pharmacokinetics, preliminary pharmacodynamics, and immunogenicity of single-dose JYB1904, an anti-immunoglobulin E (IgE) antibody, in healthy Chinese subjects.

This first-in-human study with a dose-escalation design is meant to evaluate the tolerability, safety, pharmacokinetics, preliminary pharmacodynamics, and immunogenicity of single-dose JYB1904 in healthy Chinese subjects.

The sequential dose levels (sample size) of JYB1904 are set at five different dose, with additional two JYB1904 placebo subjects in each group. The active comparator is omalizumab (Xolair).

Dosage and administration: single-dose; subcutaneous injection in the deltoid region of the upper arm.

Inclusion Criteria:

1. Able to understand the study and provide written informed consent voluntarily, and comply with the requirements;
2. Healthy Chinese subjects aged 18-50 years, male or female;
3. Normal or abnormal but without clinical significance reports of physical examinations, vital signs, clinical laboratory tests and others.

Exclusion Criteria:

1. Surgery history within 6 months prior to screening or any surgery schedule during the study;
2. Last visit in previous drug clinical trial within 3 months prior to screening;
3. Acute diseases occur or receive any medication during the screening period;
4. Other conditions unsuitable for the study confirmed by the investigator.

JYB1904/JYB1904 Placebo Arm: double-blind (participant and investigator); Omalizumab Arm: non-blind.