A Study to Assess the Safety, Tolerability, and Pharmacokinetics of ABSK-021 in Patients With Advanced Solid Tumor

Inclusion Criteria:

• Histologically confirmed solid tumors that have progressed on or intolerant tostandard therapy or whom no standard therapy exists

• ECOG (electrocorticogram) performance status 0~1

• Life expectancy ≥ 3 months

• Adequate organ function and bone marrow function

For patients with tenosynovial giant cell tumor (TGCT) :

1. A diagnosis of TGCT [i ncluding pigmented villonodular synovitis (PVNS) or giantcell tumors of the tendon sheath (GCT TS) (i) that has been histologically confirmedeither by a pathologist at the treating institution or a central pathologist, and (ii) where surgical resection would be associated with potentially worseningfunctional limitation or severe morbidity (locally advanced disease), with morbiditydetermined consensually by qualified personnel (eg, two surgeons or a multidisciplinary tumor board);

2. Measurable disease as defined by RECIST 1.1 (except that a minimal size of 2 cm isrequired), assessed from MRI scans;

3. Others

Exclusion Criteria:

• Known allergy or hypersensitivity to any component of the investigational drugproduct Previous treatment with CSF-1(colony stimulating factor 1)/CSF-1R (colonystimulating factor 1 receptor) pathway inhibitors

• Known additional malignancy that is progressing or required active treatment within 3 years of the first dose of study treatment

• Inability to take oral medication or significant nausea and vomiting, malabsorption,external biliary shunt, or significant bowel resection that would preclude adequateabsorption of oral medication

• Previous anti-cancer therapy, including chemotherapy, radiotherapy, endocrinetherapy or molecular targeted therapy within ≤ 5-halflife or ≤ 4 weeks (whichever isshorter) prior to initiation of study treatment (chemotherapy with nitrosourea ormitomycin should be 6 weeks prior to initiation of study treatment)

• Major surgery within 4 weeks of the first dose of study drug and all surgical woundsmust be healed and free of infection or dehiscence

• Prior toxicities from chemotherapy, radiotherapy, and other anti-cancer therapies,including immunotherapy that have not regressed to Grade ≤2 severity (CTCAE v5.0)with the exception of alopecia and vitiligo

• Prior corticosteroids as anti-cancer therapy within a minimum of 2 weeks of thefirst dose of study drug

• Concomitant use of strong inhibitors or inducers of CYP3A4

• Active central nervous system (CNS) metastases

• Impaired cardiac function or clinically significant cardiac disease

• Patients with Gilbert's Syndrome or other underlying conditions that may lead to agreater likelihood of developing LFT(liver function test) abnormalities during thestudy

• Known human immunodeficiency virus or active hepatitis B, or active hepatitis Cinfection

• Refractory/uncontrolled ascites or pleural effusion

• Pregnant or nursing

For patients with tenosynovial giant cell tumor (TGCT) :

1. Known allergy or hypersensitivity to any component of the investigational drugproduct

2. For expansion part, previous treatment with CSF 1/CSF 1R pathway inhibitors (notapplicable for TGCT patients in US）

3. Others