Evaluation of Safety, Tolerability, PK/PD, and Metabolism of Single-Dose Singletine(DC407) in Adults

Inclusion Criteria: * Age 18-45 years old (including both endpoints), healthy males or females; * Male weight ≥50 kg, female weight ≥45 kg, body mass index (BMI) between 19-28 kg/m2 (including both endpoints); * No significant abnormal clinical symptoms, normal physical examination, vital signs, 12-lead electrocardiogram (ECG), chest CT, ultrasound, and important indicators in laboratory tests show no clinically significant abnormalities; * Subjects (including partners) have no parenting plans within 90 days from screening to the last administration of the study drug and voluntarily adopt appropriate and effective contraceptive measures (non-oral contraceptives); * Have a full understanding of this study, voluntarily participate in the trial, and voluntarily sign the written informed consent form. Exclusion Criteria: * Pregnant or lactating women; * Subjects with special dietary requirements who cannot adhere to a uniform diet; * Subjects suspected or confirmed to be allergic to any component similar to the study drug or any ingredient in the study drug, or individuals with an allergic constitution; * Subjects with past or present severe diseases/abnormalities (including but not limited to cardiac/cerebrovascular, respiratory, endocrine, metabolic, renal, hepatic, gastrointestinal, dermatologic, malignant tumors, hematological, immunological, rheumatic, neurological or psychiatric diseases), or any acute or chronic disease or physiological condition that could interfere with the trial results; * Subjects with severe infectious diseases within six months prior to screening, or a history of herpes zoster, disseminated herpes zoster, any infectious history judged by the investigator to likely worsen due to participation in the study, or any infectious history requiring antimicrobial treatment within two weeks after screening; or the presence of active infections, including acute and chronic infections as well as localized infections; * Subjects with active or latent tuberculosis, or with a history of tuberculosis.