Inclusion Criteria:

Age 18-65 years, either sex. Patients scheduled to receive a conditioning (preparative) regimen for hematopoietic stem cell transplantation (HSCT).

Life expectancy ≥ 3 months. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. Women of childbearing potential must have a negative pregnancy test (serum or urine) within 7 days prior to enrollment.

Voluntary participation with signed informed consent.

Exclusion Criteria:

Received chemotherapy with highly emetogenic agents within 14 days prior to enrollment.

Received radiotherapy within 7 days prior to enrollment, or planned radiotherapy during the study period.

Known hypersensitivity to any study drug or its excipients. Complicated with gastrointestinal obstruction, brain metastasis with symptoms of increased intracranial pressure, or any other condition that may cause and/or exacerbate nausea and vomiting.

Active infection. Unable to take oral medications. Use of any anti-emetic medication (including corticosteroids) within 48 hours or 5 half-lives of the drug (whichever is longer) prior to enrollment.

Any episode of nausea, vomiting, or retching within 24 hours prior to the first administration.

Severe psychiatric illness or cognitive impairment that precludes understanding, reading, and completing patient diaries.

Any other condition that the investigator deems would make the patient unsuitable for participation in this study.