This is a single-center, prospective, randomized, dose-escalation Phase II clinical study. A total of 46 patients with newly diagnosed depression following allogeneic hematopoietic stem cell transplantation (allo-HSCT) will be enrolled.

Participants will be randomly assigned to receive different doses of Xiaochaihu Granules in addition to standard post-transplant care for 100 days. The primary objective is to evaluate the efficacy of Xiaochaihu Granules in improving depressive symptoms. Secondary objectives include assessment of safety and clinical outcomes such as event-free survival (EFS), graft-versus-host disease (GVHD), infections, and other transplantation-related complications.

This is a single-center, prospective, randomized, dose-escalation Phase II clinical trial designed to evaluate the efficacy and safety of Xiaochaihu Granules in patients with depression following allogeneic hematopoietic stem cell transplantation (allo-HSCT).

A total of 46 eligible patients with newly diagnosed depression after allo-HSCT will be enrolled. Participants will be randomly assigned to receive either a low-dose or high-dose regimen of Xiaochaihu Granules, administered orally twice daily for 100 days, in addition to standard post-transplant care.

The primary endpoints include changes in depression severity as assessed by validated scales (e.g., HADS and HAMD) and changes in symptom burden. Secondary endpoints include event-free survival (EFS), incidence of graft-versus-host disease (GVHD), infections, viral reactivation, engraftment outcomes, and overall safety.

Inclusion Criteria:

• Participants must meet all of the following criteria:

  1. Able to understand the study procedures and voluntarily provide written informed consent (or consent from a legal guardian where applicable);
  2. Age ≥14 years, male or female;
  3. Patients who have undergone allogeneic hematopoietic stem cell transplantation (allo-HSCT);
  4. Newly diagnosed depression after allo-HSCT, assessed by standardized scales (e.g., HADS and/or HAMD);
  5. Evidence of successful neutrophil engraftment prior to enrollment;
  6. Willing and able to comply with study procedures and follow-up assessments.

Exclusion Criteria:

1. Refusal to participate in the study;

2. Presence of severe psychiatric disorders or severe somatic symptom disorders;

3. Known allergy to Xiaochaihu Granules or any of its components;

4. Current use of other antidepressant medications;

5. Severe organ dysfunction or unstable clinical condition, including but not limited to:

   Uncontrolled bloodstream infection; Expected survival <3 months;

6. History of splenectomy;

7. Renal insufficiency with serum creatinine ≥2.0 mg/dL;

8. Cholestatic liver disease or unresolved hepatic veno-occlusive disease (VOD);

9. Significant cardiovascular conditions, including:

   Unstable angina; Acute myocardial infarction within 6 months prior to enrollment; NYHA class III-IV heart failure; Circulatory failure requiring vasoactive or inotropic support; Clinically significant arrhythmia requiring treatment;

10. Severe respiratory disease requiring mechanical ventilation or ≥50% oxygen support;

11. Patients whose primary disease is in complete remission after transplantation (per protocol definition);

12. Participation in another interventional clinical trial within 21 days prior to enrollment (or within 5 half-lives of the investigational product, whichever is longer);

13. Any other condition deemed by the investigator to make the patient unsuitable for participation.