A Study to Evaluate Safety and Efficacy of AMB-05X Injections in Subjects With TGCT

Inclusion Criteria:

1. Subject ≥ 18 years
2. TGCT with only 1 joint involvement
3. Symptomatic Measurable disease of at least 1 cm based on RECIST v1.1
4. Stable prescription of analgesic regimen
5. Agrees to follow contraception guidelines
6. Women of childbearing potential must have a negative pregnancy test
7. Adequate hematologic, hepatic, and renal function

Exclusion Criteria:

1. Prior investigational drug use within 4 weeks or 5 half-lives of Baseline
2. Previous use of therapeutics targeting CSF1 or CSF1R or oral tyrosine kinase inhibitors within 3 months prior to Baseline
3. History of extensive or reconstructive surgery on the affected joint
4. Active cancer (either currently or within 3 mo before Baseline) that requires/required therapy (e.g., surgery, chemotherapy, or radiation therapy)
5. Metastatic or malignant transformation of TGCT
6. Hepatitis C virus (HCV) or hepatitis B virus (HBV) or human immunodeficiency virus (HIV)
7. Known active tuberculosis
8. Significant concomitant arthropathy in the affected joint, serious illness, uncontrolled infection, or a medical or psychiatric history
9. Women who are breastfeeding
10. A screening Fridericia-corrected QT interval (QTcF) ≥ 470 ms
11. MRI contraindications (e.g., pacemaker, loose metallic implants)
12. History of hypersensitivity to any ingredient of the study drug
13. History of drug or alcohol abuse within 3 months before baseline
14. Any other severe acute or chronic medical or psychiatric condition or clinically significant laboratory abnormality that may increase the risk associated with study participation/treatment or interfere with interpretation of study results and, in the Investigator's opinion, make the subject inappropriate for this study
15. Subjects who, in the Investigator's opinion, should not participate in the study for any reason, including if there is a question about their ability to comply with study requirements