ABSK021-301 (Tenosynovial Giant Cell Tumor)

We are doing this study to find out if an experimental drug called ABSK021 (the study drug) is a safe and effective option for people with tenosynovial giant cell tumor (TGCT).

Tenosynovial Giant Cell Tumor (TGCT)

Adults ages 18+ who are diagnosed with TGCT.

For more information about who can participate in this study, please contact the study team at alicia.wilkerson@duke.edu.

If you join this study, you will go through a screening period to find out if you are eligible. During the screening period, you will:

• Have a full physical examination
• Provide archival tissue (past tumor biopsy tissue) or have a new biopsy
• Have blood draws
• Have imaging scans (MRI)
• Have an electrocardiogram (ECG) to check your heart function

If you are eligible to continue, you will proceed to Part 1 of the study. During Part 1, you will:

• Get a random assignment to 1 of 2 groups
• One group will take the study drug (2-out-of-3 chance to be in this group)
• The other group will get a placebo (1-out-of-3 chance to be in this group)

A placebo is an inactive substance ("sugar pill") that has no drug in it. Neither you nor anyone on the study staff will know if you are taking the study drug or placebo. However, if there is a medical need to know if you are taking the study drug or placebo, we can find this out and your participation will then end. The study drug or placebo are capsules that you will take by mouth once per day for 24 weeks during Part 1.

If you finish Part 1, you will have the option to continue on to Part 2. Everyone who chooses to participate in Part 2 will get the study drug regardless of whether or not they go the study drug in Part 1. Part 2 will last for at least 24 weeks with the possible option of continuing to take the study drug for a longer period of time.