CD26 as a Prognostic Marker in Allogeneic Hematopoietic Stem Cell Transplantation

Background: The success of hematopoietic stem cell transplantation (HSCT) depends upon donor stem cell harvest. Conventionally CD34 has been considered as marker of hematopoietic stem cells; however, the association of CD34+ cells with post-transplant outcomes has not been consistent. Current efforts are focused on identification of new markers that serve as potential predictors of post-transplant clinical outcome. Methods: This study includes donor harvests collected from twenty-three allogeneic donors during period 2008-2009 and respective transplant recipients followed for clinical outcomes till March 2019. Percent CD26+ and CD34+ cells in PBSC harvest were analyzed using flow cytometry. Infused dose of CD26+ and CD34+ cells was evaluated for its association with various clinical outcomes. Findings: Median donor and patient age was 28 and 24 years, respectively; 13 and 17 were males, respectively. Median CD34br CD45lo HSC expression was 0·57% (IQR 0·24-1·03) while median CD26 expression was 19·64% (IQR 8·96-33·56) of all nucleated cells. Lower CD26 expression correlated with lower risk of developing aGvHD (p=0·056). Higher infused CD26+ cell dose was associated with early WBC engraftment (p=0·004), higher risk of CMV reactivation (p=0·020) and a tendency to lower overall survival (p=0·066). There was no correlation between infused CD26+ and CD34+ cell dose. Interpretation: This forms the first study suggesting CD26 expression on donor harvest and CD26+ cell dose may serve as potential markers for transplant outcomes. If validated further in larger studies, it may be helpful in management of GvHD prophylaxis and improving survival with risk-based tailored therapeutics. Funding Statement: This study was funded by Indian Co-operative Oncology Network- Academic Research Organization, Mumbai, India. Declaration of Interests: Authors declare no potential financial conflicts of interest. Ethics Approval Statement: The study was approved by the institutional ethics committee. All patients and donors provided consent for study participation.