Objective: Story Of Success Of Haploidentical Hematopoietic Stem Cell Transplantation in Aplastic Anemia: A Systematic Review and Meta-analysis of Clinical Outcome and risk assessment. Authors: Ghada ElGohary1,2 1King Khalid University Hospital, Riyadh, Saudi Arabia 2Faculty of Medicine Ain Shams University, Cairo Egypt Running title: Haploidentical Stem Cell Transplantation in Aplastic Anemia.
Case report: Abstract Aplastic anemia (AA) is a very serious hematological disorder which can be solely cured by hematopoietic stem cell transplantation (HSCT). Haploidentical HSCT is a new emerging modality with encouraging outcomes in several blood conditions,yet it is still under several trials in AA Objectives: To assess the feasibility and safety of the haploidentical HSCT in patients with severe and very severe AA.
Methodology: This is a systematic review and meta-analysis of studies related to haploidentical stem cell transplantation in idiopathic aplastic anemia emphasizing the investigating rates of successful engraftment, acute graft-versus-host-disease (aGvHD), chronic GvHD (cGvHD), besides the transplant-related mortality (TRM), and post-transplantation viral infections (including cytomegalovirus [CMV]) in patients with AA.
Results: The effects of reduced intensity (RIC) and non-myeloablative conditioning (NMA) as well as various GvHD-prophylaxis regimens on these outcomes were evaluated in our study. In total of fifteen studies that were identified, (577 patients, 58.9% males), successful engraftment was observed in 97.3% of patients (95% CI, 95.9–98.7) while grade II-IV aGvHD and cGvHD has been reported in 26.6% and 25.0%, respectively. The incidence of TRM was 6.7% per year (95% CI, 4.0 to 9.4). RIC regimens were associated with higher proportions of successful engraftment (97.7% vs. 91.7%, p=0.03) and aGvHD (29.5% vs. 18.7%, p=0.008) when compared to NMA regimens with no differences in cGvHD or mortality incidence. When compared to methotrexate-containing regimens and other regimens, post-transplant-cyclophosphamide-containing regimens (PTCy) has helped to reduce the rates of aGvHD (28.6%, 27.8%, and 12.8%, respectively, p=0.02), CMV viremia (55.7%, 38.6%, and 10.4%, respectively, p<0.001), and CMV disease in initially-viremic patients (2.1%, 33.0%, and 0%, respectively, p<0.001).
Conclusion: We can conclude that Haploidentical HSCT is associated with promising outcomes in terms of successful engraftment and reduced complications. Engraftment success has been noticed in the majority of patients with severe and very severe AA, while TRM and GvHD rates were acceptable. NMA conditioning was better in terms of lower CMV viremia and acute GVHD but not in terms of RRT, mortality and engraftment. The addition of PTCy regimens have showed lower GvHD and lower CMV incidence at a price of non-significant increase in the incidence of mortality per year. NMA vs. RIC and PTCy vs others may be used depending on both patient's and donor's profiles besides each institution's setup and resources Recommendation: Still we are in need of more studies to weigh the risk and benefits of Haplo SCT in AA.
