Inclusion Criteria:
1. Recurrent or refractory neuroblastoma or solid tumor.
2. Physical state score ≥ 50.
3. Expected survival ≥ 3 months.
4. There are target lesions (neuroblastoma) or measurable lesions (other solid tumors).
5. Have adequate organ function.
6. Fresh or archived tumor tissue samples should be provided prior to treatment. If none of these specimens are available, inclusion may be made after consultation with the sponsor.
7. Fertile women (≥14 years of age or having menarche) must have a negative serum pregnancy test at the time of the screening visit and must not be breastfeeding or planning to become pregnant during the study period.
8. A potentially fertile male subject (who has spermatoses) or female subject (ibid.) must agree to use effective contraception during the trial period and for 3 months after the trial ends (or is prematurely discontinued).
9. Informed consent must be obtained before carrying out any study procedure specified in the test. For child subjects, the consent of the subject and one of the parent/legal guardian must be obtained.
10. The ability to swallow research drugs.
Exclusion Criteria:
1. Systemic antitumor therapy, including biotherapy, chemotherapy, surgery, radiotherapy, immunotherapy, and other investigational drug therapy (other than placebo), was received within 21 days prior to the first treatment with the study drug.
2. Small-molecule targeted drug therapy was administered 14 days before the first treatment of the study drug or within a known five-half-life period, whichever is shorter.
3. Patients who, according to the investigators' judgment, did not recover sufficiently after surgical treatment. Patients who underwent major surgery within 28 days before receiving the study drug for the first time.
4. Adverse events due to previous antitumor therapy (except grade 2 peripheral neurotoxicity and alopecia that the investigators judged to be of no safety risk) have not recovered (severity higher than grade 1 according to CTCAE version 5.0).
5. Patients with active brain tumors or brain metastases.
6. Active gastrointestinal diseases (e.g. Crohn's disease, ulcerative colitis, or short bowel syndrome) or other malabsorption syndromes that may affect drug absorption.
7. A known hemorrhagic predisposition/disease, such as a history of non-chemotherapy-induced thrombocytopenic bleeding within 1 year before first receiving the study drug; Have active immune thrombocytopenic purpura (ITP), active autoimmune hemolytic anemia (AIHA), or a history of platelet transfusion failure (within 1 year before first receiving the study drug); Severe gastrointestinal bleeding occurred within 3 months.
8. Clinically significant cardiovascular disease, cardiomyopathy, myocardial infarction or history within 6 months prior to administration.
9. Symptomatic active fungal, bacterial, and/or viral infections requiring systemic treatment.
10. Unexplained fever \> 38.5℃ within 2 weeks prior to initial administration (subjects with tumor-related fever, as determined by the investigator, could be enrolled).
11. Received MDM2 inhibitors or BCL-2 inhibitors.
12. Any other circumstances or conditions that the investigator considers the patient inappropriate for participation in the study.
