AML-446: CD34+ Dosing and Correlation with Cytokine Release Syndrome in Haploidentical SCT

Abstract

Introduction: Optimum dosing of CD34+ haploidentical stem cells in allogeneic stem cell transplant is not clear. Investigators have shown better outcomes with higher doses of CD34+ stem cells, but there is a concern for higher rates of cytokine release syndrome (CRS). We investigated the dosing of CD34+ stem cells at our institute. The aim of this study was to find out if higher dosing resulted in higher rates of CRS and if CD34+ dose affected 1-year GRFS (graft-vs-host disease relapse-free survival), OS (overall survival), and RFS (relapse-free survival). Method: Retrospective chart review of patients who underwent haploidentical stem cell transplant at Norris Cancer Center. Patients who received CD34+ + ≤ 5×106/kg were included in group A, and CD34+ >5×106/kg were included in group B. Results: A total of 103 patients were reviewed, 55% male and 45% female, the majority of which were Hispanic (62%). The most common diagnoses were AML (40%) and ALL (34%). CD34 did not correlate with aGVHD, cGVHD, grade 2 CRS, or pressor requirement, but it was significantly correlated with the grade 3 CRS requirement for oxygen, and ICU admission increased with higher CD34 doses. We did not find any significant difference in 1-year GRFS (p-value=0.297), OS (p-value=0.151), or RFS (p-value=0.175) between both groups. Conclusion: Our review raises some concerns that higher doses of CD34+ are correlated with higher rates of cytokine release syndrome, and optimum dosing should be studied in prospective trials.