A safe, carefully dosed test of TBD11 in healthy adults

Inclusion Criteria:

* 18 to 55 years of age, inclusive.
* Healthy, as determined by the Investigator through medical history and clinical examination before enrolment.
* Able to understand and comply with trial and site procedures, understand study risks, and provide written informed consent before any trial-specific procedure.
* Able to complete all Screening evaluations and remain in the clinical research facility for required inpatient periods.
* BMI between 18 and 32 kg/m², inclusive, and body weight of at least 50 kg at Screening.
* Resting vital signs within protocol-defined ranges at Screening and Day -1.
* 12-lead ECG consistent with normal cardiac conduction and function at Screening.
* Non-smoker within the previous 90 days, with negative urine cotinine at Screening and no use of tobacco- or nicotine-containing products.
* Screening clinical chemistry, coagulation, complete blood count, and urinalysis within laboratory reference ranges, unless assessed as not clinically significant by the Investigator/designee.
* Negative HBsAg and HCV antibody at Screening.
* Negative IGRA test for TB infection.
* Negative HIV antibody test at Screening.
* Negative urine drug screen and urine alcohol screen at Screening and Day -1.
* For participants assigned female sex at birth: negative urine and serum pregnancy tests at Screening and non-childbearing potential as defined in the protocol.
* For participants assigned male sex at birth who are not sterilized and sexually active with a female partner of childbearing potential: agreement to use condoms from Day -1 through 90 days after the last dose and not donate sperm during the trial and for 90 days after the last dose.

Exclusion Criteria:

* Current or past clinically significant cardiovascular, cerebrovascular, respiratory, gastrointestinal, haematologic, renal, hepatic, immunologic, metabolic, urologic, neurologic, dermatologic, psychiatric, or other major disease.
* Current or past condition expected to require treatment during the trial with medication known to inhibit or induce CYP3A4.
* Clinically relevant cardiovascular disorder or symptoms suggestive of such disorder.
* Prior history of TB infection or TB disease.
* Current cough lasting more than 2 weeks, fever, night sweats, or unexplained weight loss.
* Close household or repeated living/workspace contact with an individual with active TB in the preceding 12 months.
* Active malignancy within 5 years of Screening, except basal cell or squamous cell skin cancers; any history of breast cancer or melanoma is exclusionary.
* History of drug abuse within 1 year before Screening or use of specified hard drugs within 1 year before Screening, unless limited to prescribed opioid or amphetamine medication not currently being taken.
* Surgical or medical condition that may alter absorption, metabolism, or excretion of trial treatment.
* Use of prohibited medications, vitamins, dietary supplements, herbal products, or vaccination within the protocol-defined windows.
* Contraindication to trial interventions or excipients, or clinically significant allergic/anaphylactic reaction to any medication.
* Participation in another investigational drug, vaccine, or device study within 30 days or 5 half-lives, whichever is longer, before Screening and during this trial.
* Any condition that may interfere with informed consent, compliance, interpretation of results, or place the participant at undue risk.
* Blood donation within 2 months before Screening or planned blood donation during the trial or within 12 weeks after the final visit.