A First-in-human Single Ascending Dose/Multiple Ascending Dose Study of ENN0403 in Healthy Subjects

Inclusion Criteria: * Capable of giving signed informed consent. * 18 to 55 years old (inclusive). * BMI of 18 to 30 kg/m2 (inclusive); body weight \>50 to \<100 kg for male subjects or \>45 to \<100 kg for female subjects. * Computerized (12-lead) ECG recording without signs of clinically relevant pathology or showing no clinically relevant deviations as judged by the PI. * Test negative for COVID-19. * Test negative for HBsAg, anti-HBc, anti-hepatitis C virus (HCV) antibodies, anti-human immuno deficiencyvirus (HIV) 1 and 2 antibodies, and tuberculosis. * Have a negative urine drug screen and a negative alcohol breath test. * Nonsmoker or occasional smoker and willingness to refrain from smoking during study. * Ability and willingness to abstain from alcohol during study. * not pregnant, not breastfeeding; apply contraception methods for child-bearing potential subjects. Exclusion Criteria: * History of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal,cardiovascular, hepatic, psychiatric, neurologic, or allergic disease in the opinion of the Investigator within 12 months prior to Screening. * Any disease or take any medication that affects IP absorption, distribution, metabolism, and excretion.3. Family history of sudden death or of congenital prolongation of the QTc interval or known congenital prolongation of the QTc interval or any clinical condition known to prolong the QTc interval. * Presence of malignancy including hematological malignancies. Subjects with a history of basal cell or squamous cell carcinoma that has been treated with no evidence of recurrence within 3 years of Screening will be allowed for inclusion, as judged by the Investigator. * Any current active infections, including localized infections, or any recent history (within 1 week prior to IP administration) of active infections, cough or fever; or a history of recurrent or chronic infections. * In the 12-lead ECG assessment, QTcF \>450 ms for male subjects or \>470 ms for female subjects.7. Estimated glomerular fltration rate \<90 mL /min (using the Cockcroft-Gault formula) at Screening. * ALT or aspartate aminotransferase\>1.5ULN. * Have received any live vaccines (bacterial or viral) within 12 weeks prior to Screening or intend to receive a live vaccine during the study period or within 30 days after the last dose of the IP.