XS-02 capsules in adults with advanced solid tumors

Patients must meet all of the following criteria for admission:

1. Volunteer to participate in clinical trials and sign an informed consent form (ICF).
2. Age ≥18 years old, ≤75 years old, regardless of gender.
3. Phase Ia: patients with histologically or cytologically confirmed locally advanced or metastatic solid tumors for whom no standard therapy is available, who have failed standard therapy, or who are intolerant of standard therapy. In the Phase Ib dose-expansion stage, Cohort A will enroll patients with advanced serous endometrial cancer who have failed prior standard therapy, and Cohort B will enroll patients with osteosarcoma who have failed prior standard therapy or are intolerant of standard therapy..
4. The phase Ia dose escalation has at least one evaluable lesion; in the phase Ib dose expansion has at least one measurable lesion (based on RECIST V1.1). For patients who have previously received radiation therapy, a radiation-treated lesion may be considered a target lesion if the lesion can be measured according to RECIST V1.1 and there is objective evidence of significant progression after radiation therapy.
5. All participants enrolled in phase Ib must provide a sufficient quantity of tumor tissue samples and control blood samples for predictive biomarker analysis.

6: The Eastern Cooperative Oncology Group (ECOG) scored 0-1, with no deterioration within 2 weeks prior to the first dose. Osteosarcoma patients with an ECOG score of 2 due to functional impairment caused by prior surgical resection or due to the anatomical location of the tumor might be enrolled at the investigator's discretion.

7：The expected survival time is ≥3 months. 8：Routine blood tests before first dosing must be within the following range (no blood transfusion or use of drugs that assist in raising white blood cells, platelets, hemoglobin, such as cytokines or erythropoietin, etc., for at least 7 days prior to first dosing) a. Hemoglobin (HB) ≥90 g/L. b. Platelet (PLT) count ≥100×10\^9/L. c. Absolute count of neutrophils (ANC) ≥1.5×10\^9/L.

9：Has proper organ function 10：Female subjects of reproductive age in the screening period had negative serological pregnancy test results within 7 days prior to the first dosing. The subjects also agreed to use a reliable method of contraception for 3 months from signing the informed consent to the last dosing. Including but not limited to: forbidden Sex, male vasectomy, female sterilization, effective IUD, condoms, effective contraceptive drugs.

11：Patients were able to comply with the visits required by the study procedure and protocol.

Patients who meet any of the following conditions are not allowed to enter this clinical study:

1. Chemotherapy, small molecule targeted therapy, endocrine therapy and traditional Chinese medicine with anti-tumor indications were received within 2 weeks prior to the first dose. Received tumor immunotherapy, antibodies, polypeptide antitumor, or other investigational drugs within 4 weeks prior to initial administration.
2. Patients who had undergone therapeutic surgery other than diagnosis, biopsy, drainage, or radical radiotherapy within 4 weeks prior to initial dosing, or who expected to undergo major surgery during the study period. Had received palliative radiotherapy within 2 weeks prior to the first dose, or had used radiopharma (strontium, samarium, etc.) within 56 days prior to the first dose.
3. The toxicity of previous antitumor therapy has not recovered (\> NCI-CTCAE 5.0 grade 1),alopecia, pigmentation, or other toxicity that the investigators assessed had become chronic and did not affect the safety of the investigational medication returned to NCI-CTCAE 5.0 level 2 or below.

4:Imaging (CT or MRI) shows that the tumor has invaded large blood vessels (such as aorta, pulmonary artery, pulmonary vein, vena cava, etc.) or is at risk of bleeding (such as esophageal and gastric varices) or fistula.

5: Osteosarcoma patients with severe tumor-induced bone injury that has occurred or may occur after enrollment, such as pathologic fractures of weight-bearing bones or spinal cord compression that have occurred within 3 months or may occur after enrollment; or uncontrolled pain related to bone metastases.

6: Inflammatory breast cancer 7: There is clinically uncontrolled pleural effusion, pericardial effusion, or ascites requiring repeated drainage or medical intervention (within 2 weeks prior to administration).

8: Patients with central nervous system metastasis who meet any of the following conditions: a. need to undergo local treatment (surgery, radiation or other); b. Patients who require steroid hormones, anticonvulsants, or other dehydration treatment; c. Meningeal, midbrain, pontine, bulbar, or spinal cord metastases. Only patients with BMS who were asymptomatic, stable on imaging assessment (no significant progression of brain metastases on imaging assessment within the first 4 weeks of enrollment) and did not require treatment were admitted. d. Presence of spinal cord compression, or brain or CNS injury.

9: Patients with difficulty swallowing, or a history of severe gastrointestinal disease (e.g. active inflammatory bowel disease, gastrointestinal perforation) and related symptoms that cannot be reasonably controlled; Or have a gastrointestinal disorder (e.g., Crohn's disease, ulcerative colitis, intestinal obstruction, short bowel syndrome) or other malabsorption conditions that affect drug absorption.

10: Have active or unstable cardiovascular disease 11: Bacterial, fungal, or viral infections requiring intravenous antibiotics/antivirals or hospitalization were investigated within 2 weeks prior to initial drug administration.

12: People who have a history of prior severe allergies or are allergic to any active or inactive ingredient of the investigatory drug.

13: Known acute or active hepatitis B (HBV surface antigen positive with HBV DNA≥500 IU/mL), hepatitis C virus infection (HCV RNA exceeding the normal range), syphilis infection, and human immunodeficiency virus (HIV) infection.

14: Other primary malignancies have been diagnosed within the previous five years (the following conditions can be included: cured and completely resected basal and squamous cell skin cancers, completely resected cancers of any type in situ).

15: Use within 2 weeks prior to first administration or expect to use a CYP3A booster or strong inducer during study drug administration.

16: Use within 2 weeks prior to first administration, or expect to use any drug known to prolong the QTc interval during study drug administration.

17: The ATR/CHK1 pathway has been treated in the past. 18: Had a bone marrow transplant or had extensive radiation therapy on more than 25% of the bone marrow in the 8 weeks prior to initial dosing.

19: A history of blood clotting disorders; Anticoagulant or antiplatelet therapy (oral aspirin dose ≤100 mg/d and subcutaneous injection of low molecular weight heparin for prevention of deep vein thrombosis) is required.

20: Pregnant and lactating women. 21: According to the judgment of the investigator, any other serious or uncontrolled acute or chronic medical or psychiatric condition, or abnormal laboratory tests or other reasons are not suitable for participation in this clinical study.