PTCy Improves Outcomes for Stem Cell Transplants, Regardless of HLA Match

Close-up of hematopoietic niche in bone marrow: ©artsakon - stock.adobe.com

The use of posttransplant cyclophosphamide (PTCy) led to similar overall survival (OS) and graft-vs-host disease (GVHD) relapse-free survival (GRFS) between patients with HLA-matched unrelated donors (MUD) and mismatched unrelated donors (MMUD), according to research published in the Journal of Clinical Oncology.

These findings significantly expand patients’ access to potentially lifesaving hematopoietic cell transplantation (HCT), especially for those from minority ethnic backgrounds.

A total of 10,025 patients who underwent HCT between June 2017 and January 2021 for acute leukemia (70.9%) or myelodysplastic syndrome (29.2%) were included in the analysis, and data was obtained from the Center for International Blood and Marrow Transplant Research (CIBMTR) database. There was no difference in OS based on HLA matching for patients that received PTCy (HR, 0.96; 95% CI, 0.82-1.11; P =.60). Comparatively, there were notable differences in OS for patients that received calcineurin inhibitor (CNI)-based prophylaxis (HR for MUD, 0.80; range, 0.70-0.92; P =.016).

PTCy also delivered better OS results for patients receiving MUD HCT compared with CNI (HR, 0.88; 95% CI, 0.804-0.96; P =.0041). This was also true for patients receiving MMUD HCT with PTCy (HR, 0.92; 95% CI, 0.80-1.05; P =.2062). MUD or MMUD patients receiving PTCy were less likely to experienced GVHD than patients receiving CNI.

“…The use of posttransplant cyclophosphamide has clearly been a major advantage the field and has taken the field in another direction in terms of using alternative donor transplants, specifically enabling more ethnically diverse patients to receive stem cell transplant,” said Jeff Auletta, MD, senior vice president of health equity at the National Marrow Donor Program and chief scientific officer at CIBMTR, in an interview with Targeted OncologyTM.

The study contained a subgroup analysis of patients of minority ancestry who underwent MMUD HCT with PTCy. For these patients, the 3-year OS rate was 60% (range, 52%-67%). Comparatively, this rate was 59% (range, 53%-64%) for non-Hispanic White patients. Further, the 3-year GRFS rate was 42% for both patients of minority ancestry and non-Hispanic White patients. The use of PTCy also improved OS (HR, 0.56; 95% CI, 0.40-0.79; P =.001) and GRFS (HR, 0.57; 95% CI, 0.43-0.76; P <.001) rates in patients of minority ancestry compared with CNI.

“The results demonstrate comparable outcomes between MUDs and MMUDs when using PTCy, suggesting that MMUDs are a suitable donor option if a MUD is not available. Differences in OS between MUD and MMUD HCT continue to be observed after CNI-based GVHD prophylaxis without PTCy, suggesting the results are not simply because of recent changes in supportive care,” study authors wrote.

Researchers also included an analysis of available donors in the National Marrow Donor Program and World Marrow Donor Association registries. Across all major ancestry groups, the chance of having at least 1 unrelated donor improved if matched and mismatched donors were considered.

“Taken together, these results and those of forthcoming clinical trials will represent a significant step forward in resolving barriers to transplantation. Increasing access to HCT is paramount to making this lifesaving procedure available to patients of all ancestries,” study authors concluded.

REFERENCE:

Shaffer BC, Gooptu M, DeFor TE, et al. Post-transplant cyclophosphamide–based graft-versus-host disease prophylaxis attenuates disparity in outcomes between use of matched or mismatched unrelated donors. J Clin Oncol. 2024;0. doi:10.1200/JCO.24.00184