Improved Outcomes with Allogeneic Stem Cell Transplantation for Aplastic Anaemia Using HLA Identical Sibling Donors: The Indian Stem Cell Transplant Registry (ISCTR) Experience

Introduction: Allogeneic stem cell transplantation (SCT) is the best form of therapy for a young patient (< 50 years) with severe aplastic anaemia. In developing countries, there is a big time interval between diagnosis and SCT leading to increased transfusions and increased risk of infections, both of which adversely affects transplant outcome. This retrospective analysis is aimed at studying the outcomes of SCT among Indian patients with aplastic anaemia.

Methodology: The Indian Stem cell transplant registry (ISCTR) is a group of transplant physicians representing about 30 active transplant centres in India. This retrospective analysis was done on data reported on 634 patients by 20 centres who reported outcomes of SCT for aplastic anaemia. Data was collected from individual medical records and databases. Analysis was done using SPSS software version 16.0

Results: Six hundred and thirty four patients [445 males and 189 females] with a median age of 21 years (range: 2 - 65) underwent allogeneic SCT between 1990 and March 2015. There were 209 children (age < 15 years). The median time from diagnosis to SCT was 5 months (range: 1 - 120) while the median number of transfusions was 20 (range: 1 - 150). All donors were HLA identical sibling or family donors; matched unrelated and haplo-identical donor transplants were excluded from this analysis.

Conditioning regimen was Cyclophosphamide based (Cy/ Cy+ ATG/ Cy+ TBI/TLI) in 78 patients (12.3%) while majority received Fludarabine with Cyclophosphamide (n = 481; 75.8%) and 75 received other conditioning regimens (Flu/TBI, Flu/Bu, Bu/Cy etc). Graft source was bone marrow [BM] in 124 (19.5%) and peripheral blood stem cells in 510 patients (80.5%). Graft versus host disease (GVHD) prophylaxis predominantly consisted of Cyclosporine and methotrexate in 543 patients (85.6%).

Engraftment was seen in 572 patients (90.4%) while 19 (2.9%) had primary graft failure and 43 (6.7%) expired prior to engraftment due to infection or bleeding. The median time to neutrophil engraftment was 13 days (range: 8 - 21) while platelet engraftment occurred at 13 days (range: 5 - 37). Grade II - IV acute GVHD occurred in 29.3% while grade III-IV was seen in 14.1%. Chronic GVHD was seen in 41% of evaluable patients which was limited in most patients. At a median follow up of 43 months (range: 1 - 264), 431 patients are alive. The 5 yr OS for the entire group is 66.3 + 2.0%. The OS was higher in children compared to adults (73.4 + 3.3% vs 62.8 + 2.5%; p = 0.006), better for Flu/Cy compared to Cy based conditioning (69.8 + 2.2% vs 57.8 + 5.6%; p = 0.002) and better for PBSC compared to BM (68.9 + 2.2% vs 56.1 + 4.8%; p = 0.020). There has been significant improvement in outcomes over the past 15 years [3 yr OS of 41.9 + 1.3% for 1984-1995, 40.9 + 1.2% for 1996-2000, 70.6 + 5.0% for 2001 -2005, 70.3 + 3.1% for 2006-2010 and 68.8 + 3.0% from 2011 onwards].

Conclusion: Outcomes of patients with aplastic anaemia are improving and patients have a 70% chance of getting cured with a HLA identical sibling donor transplant. The use of PBSC as graft source is not associated with inferior outcomes.