Modifying Post-Transplant Cyclophosphamide Platform to Improve Safety in HLA-Matched Allogeneic HCT: A Reduced Dose...

Area of Science:

• Hematology
• Immunology
• Oncology

Background:

• Post-transplant cyclophosphamide (PTCY) is effective for GVHD prophylaxis in HLA-matched allogeneic hematopoietic cell transplantation (allo-HCT).
• Standard PTCY (50 mg/kg/day) is associated with early toxicities, prompting investigation into modified regimens.

Purpose of the Study:

• To evaluate the safety and efficacy of a modified GVHD prophylaxis using reduced-dose PTCY (PTCY40).
• To compare outcomes of PTCY40 with standard PTCY50 in allo-HCT recipients.

Main Methods:

• A modified platform using PTCY40, tacrolimus, G-CSF, and letermovir was implemented in November 2021.
• Outcomes of 56 patients receiving PTCY40 were compared to 59 historical controls treated with PTCY50.

Main Results:

• PTCY40 demonstrated faster neutrophil and platelet recovery, improved CD4+ T-cell reconstitution, and fewer bloodstream infections by day +30.
• Non-relapse mortality was significantly lower with PTCY40 (0% vs 8.6%, P = .032).
• Acute GVHD incidence was comparable, while moderate/severe chronic GVHD was numerically higher but not significant.

Conclusions:

• The modified GVHD prophylaxis with reduced-dose PTCY40 is associated with improved early recovery and reduced non-relapse mortality.
• This approach supports the safety and efficacy of a modified GVHD prophylaxis strategy in allo-HCT.