(181) Outcomes of Alemtuzumab or Post Transplant Cyclophosphamide-based Graft-Versus-Host-Disease Prophylaxis in Adult Patients with Allogeneic Hematopoietic Stem Cell Transplantation

Poster Abstract:

Background:
The development of acute or chronic graft-versus-host-disease (GVHD) is a major complication in allogeneic HCT (allo-HCT) that can significantly impact mortality and quality of life for patients. Alemtuzumab (Campath-1H) is a humanized IgG1 monoclonal antibody that has shown benefit when incorporated into preparative regimens as part of a GVHD prophylactic strategy. Numerous studies have highlighted its effectiveness in reducing the incidence of GVHD and treatment-related mortality. Conversely, there are concerns of an increased risk of relapse, which may impact overall survival outcomes. There is currently a gap in literature of a standardized approach that incorporates alemtuzumab.
Houston Methodist Hospital utilizes alemtuzumab routinely in preparative regimens for patients undergoing allo-HCT with unrelated donors to reduce the risk of GVHD. Moreover, the institution has recently utilized an emerging prophylactic regimen involving post-transplant cyclophosphamide (PTCy) given its recent publication with improved outcomes in GVHD-free, relapse-free survival (GFRS) compared to conventional methods. Given the absence of direct comparisons, outcomes associated with these two practices are of interest to the institution.
Objective(s):
This research aims to retrospectively analyze GVHD and survival outcomes in recipients receiving alemtuzumab-based and PTCy-based GVHD prophylaxis regimens at Houston Methodist Hospital

Methods:
A single-center retrospective chart review was conducted on allo-HCT recipients who received alemtuzumab-based or PTCy-based preparative regimen from August 1st, 2017 – August 31st, 2022. Patients 18 years of age and older with matched or mismatched unrelated donor allo-HCT were included. Patients who have received alemtuzumab after HCT for treatment of acute GVHD or had undergone more than one transplantation were excluded. The primary endpoint is to evaluate the GFRS of patients receiving the regimens described above. Secondary endpoints will include overall survival, relapse-free survival, event-free survival, transplant-related mortality, neutrophil engraftment, incidence of acute GVHD or chronic GVHD, and donor chimerism at days 28 and 100.

Results:
135 patients in the alemtuzumab arm and 10 patients in the PTCy arm met inclusion and exclusion criteria. Within the alemtuzumab arm, the median age is 61 (IQR 48 – 67) years. 68 (50%) patients received reduced-intensity preparative regimens, while 67 (50%) underwent myeloablative regimens. Of the donor sources, 103 (76%) were of matched unrelated status while 32 (31%) were mismatched-unrelated. Data collection and analysis are ongoing. Finalized results will be presented at HOPA.

Conclusion:
Considering the institution’s extensive use of alemtuzumab, substantial data is available to describe survival outcomes and findings will be contributed to existing literature

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