Graft failure is a fatal complication following allogeneic stem cell transplantation where a second transplantation is usually required for salvage. There are no recommended regimens for second transplantations for graft failure, especially in the haploidentical transplant setting. We recently reported encouraging outcomes using a novel method (haploidentical transplantation from a different donor after conditioning with fludarabine and cyclophosphamide). However, the study was performed in single-center and with very small sample size. Therefore, it should be further validated via multicenter study. In this multi-center study, we aim to further evaluate the safety and efficacy of this protocol.

Inclusion Criteria:

• 1. Primary disease: hematological malignancies (AML, CML, MDS, lymphoma, etc.); 2. Graft failure after the first haploidentical stem cell transplantation; 3. Time from the first transplantation to the second transplantation is less than 180 days; 4. Age≥14 years.

Exclusion Criteria:

• 1. Active infections; 2. Active GVHD; 3. Organ dysfunction: hepatic injury (Tbil≥2ULN), renal injury (Cr≥1.5ULN), heart injury (EF%<50% or symptomatic heart failure); 4. Eastern Cooperative Oncology Group (ECOG) score>2; 5. Expected life time<30 days; 5. Patients could not cooperate; 6. Other situations that are considered inappropriate for enrollment by the investigators,