This study aims to evaluate whether immediate allogeneic hematopoietic stem cell transplantation (HSCT) is non-inferior to HSCT following bridging therapy in patients with higher-risk myelodysplastic syndrome (HR-MDS).

A total of 236 patients will be randomized in a 1:1 ratio into the immediate transplantation group (n=118) and the disease control group (n=118). The study will continue until at least 124 events occur.

Inclusion Criteria:

1. Age ≥18 years

2. High relapse risk MDS, defined by:

   • IPSS-R score ≥3.5.
   • IPSS-M stratification as intermediate-high, high, or very high risk.

3. Eligible for allogeneic HSCT (including matched or mismatched related/unrelated donor transplantations).

4. Karnofsky Performance Status (KPS) ≥60.

5. Signed informed consent.

Exclusion Criteria:

1. Severe organ dysfunction:

   • Left ventricular ejection fraction <50%.
   • Oxygen supplementation requirement.
   • Serum bilirubin >1.5x upper limit of normal (unless due to Gilbert syndrome) or AST/ALT >5x upper limit of normal.
   • Estimated glomerular filtration rate (eGFR) <50 mL/min.

2. History of prior allogeneic HSCT.

3. Any condition deemed unsuitable by the investigator.