Reduced Intensity Haploidentical Stem Cell Transplantation with CD34 Selection and Addback of Regulatory and Conventional T Cells

Abstract

We conducted a retrospective analysis of cellular components of bone marrow graft for CD3+ T, CD34+ and Natural killer (NK) cells and their relationship on survival in 64 highrisk Acute Lymphocytic Leukemia (ALL) patients who received Hematopoietic stem cell transplant (HSCT), 35 from matched sibling donors and 29 matched unrelated donors from the year of 2000 to 2013. The grafts contained a median CD34+ cells dose of 4.8 x 10 6 /kg (range 0.8-14x10 6 /kg), CD3+ T cells 3.6x10 7 /kg (range 1.1-36.9x10 7 /kg), and NK cells 0.8 x 10 7 /kg (range 0.07-20.6 x 10 7 /kg). The median days for absolute neutrophil count engraftment were 24 (range 14-100) and for platelet 28 days (range 14-180). We conducted a point-biserial correlation examining CD3 + cells with likelihood of survival and relapse. Results showed that ALL patients who received higher CD3+ cells were more likely to survive than those patients with lower CD3 + cells (p¼0.031). Additionally, we found that the positive effect of CD3+ cells was noted with a minimum cell dose of 2.2x10 7 /kg which was associated with better survival without relapse and was statically significant with p value of 0.022. However, we were unable to demonstrate any significant impact of NK cells contents of the graft on survival or relapse (p ¼ 0.257 and 0.722 respectively). In conclusion, this study showed a positive correlation between CD3+ T cells dose in bone marrow graft and survival post-transplant with a minimal cell dose of 2.2x10 ˇ 7 /kg