Graft Failure Incidence, Risk Factors, and Outcomes in Patients Undergoing Non-Myeloablative Allogeneic Hematopoietic...

Area of Science:

• Hematology
• Immunology
• Oncology

Background:

• Graft failure (GF) is a serious complication of allogeneic hematopoietic cell transplantation (alloHCT).
• Post-transplant cyclophosphamide (PTCy) is effective for graft-versus-host disease (GVHD) prophylaxis.
• Characteristics of GF with PTCy prophylaxis are not well-defined.

Purpose of the Study:

• To determine the incidence, clinical features, risk factors, and outcomes of primary graft failure (PGF) and secondary graft failure (SGF).
• To analyze GF in patients undergoing nonmyeloablative (NMA) alloHCT with PTCy-based GVHD prophylaxis.

Main Methods:

• Retrospective analysis of 958 consecutive patients undergoing first NMA alloHCT with PTCy prophylaxis.
• Defined PGF as failure to achieve ANC ≥ 500 cells/mL by day 30 without residual disease.
• Defined SGF as complete loss of donor chimerism post-engraftment.

Main Results:

• Incidence rates: PGF 3.8%, SGF 1.8%.
• PGF risk factors: age ≥ 65, MDS/MPN diagnoses, HHV-6 viremia, low CD34+ dose.
• SGF associated with bone marrow graft source and Hodgkin lymphoma; PGF associated with poor survival (59% nonrelapse mortality at 36 months).

Conclusions:

• PGF and SGF incidence is low in NMA alloHCT with PTCy and not affected by HLA disparity.
• PGF is associated with adverse factors and poor outcomes, primarily due to nonrelapse mortality.
• SGF is linked to specific factors but has excellent long-term outcomes.