Long-term outcomes after haploidentical stem cell transplantation for hematologic malignancies

Area of Science:

• Hematology
• Transplant Immunology
• Oncology

Background:

• Posttransplant cyclophosphamide (PTCy) has revolutionized haploidentical stem cell transplantation (haplo-SCT) by improving graft-versus-host disease (GVHD) prophylaxis.
• Assessing long-term outcomes is crucial for understanding the sustained efficacy and safety of PTCy-based haplo-SCT.

Purpose of the Study:

• To retrospectively evaluate the long-term survival and outcomes of patients undergoing their first haplo-SCT with PTCy-based GVHD prophylaxis.
• To identify predictive factors for long-term success and late complications after PTCy-based haplo-SCT.

Main Methods:

• Retrospective analysis of 335 patients who underwent haplo-SCT between February 2009 and March 2019.
• Defined long-term survivors as those alive and disease-free at 2 years post-transplant.
• Analyzed progression-free survival (PFS), overall survival (OS), relapse rates, and non-relapse mortality (NRM).

Main Results:

• The overall 4-year PFS and OS for all patients were 42% and 47%, respectively.
• Long-term survivors (alive and disease-free at 2 years) demonstrated excellent 4-year PFS (94%) and OS (96%).
• Age ≥55 years was the sole significant predictor of inferior PFS and OS (P < .05). Late relapses were rare (2.9% cumulative incidence), and secondary primary malignancy was the leading cause of non-relapse mortality.

Conclusions:

• PTCy-based haplo-SCT offers excellent long-term survival for patients achieving disease-free status at 2 years post-transplant.
• Late relapses are uncommon, and non-relapse mortality is low in this cohort.
• Age is a critical factor influencing long-term outcomes in PTCy-based haplo-SCT.