Allogeneic stem cell transplant in primary hemophagocytic lymphohistiocytosis - a single-center experience.

Hemophagocytic Lymphohistiocytosis (HLH) is a rare disorder of immune dysregulation characterized by fever, cytopenias, and splenomegaly. Its primary form poses a therapeutic challenge due to its high fatality when left untreated. We retrospectively analyzed 28 patients who underwent related-donor allogeneic stem cell transplant for primary HLH from 2010 to 2021. Among them were 10 cases of familial HLH, 8 cases of Griscelli syndrome type 2, and 1 case each with PRF1 and STX11 mutations. All the patients underwent transplants with reduced-intensity or myeloablative conditioning and 26 of them achieved neutrophil engraftment at a median of day + 14. The donors were either fully matched (68%) or haploidentical (32%). With a median follow-up of 1 year, overall survival was 68% (n = 19) and disease-free survival was 64.4% (n = 18). OS was better in patients transplanted with a sibling donor (compared to parent donor), who achieved complete donor chimerism, and those transplanted early in the course of the disease (diagnosis to transplant duration less than 6 months).

Acute Graft versus Host Disease in Beta Thalassemia Patients Following Allogeneic Haematopoietic Stem Cell Transplantation.

OBJECTIVE: To analyse the frequency, risk factors, and clinical symptoms of acute graft-versus-host disease (aGvHD) in patients with beta-thalassemia major after allogeneic haematopoietic stem cell transplantation (HSCT). STUDY DESIGN: Descriptive study. Place and Duration of the Study: Department of Clinical Haematology, Armed Forces Bone Marrow Transplant Centre, Rawalpindi, Pakistan, from January 2017 to December 2021. METHODOLOGY: Data were obtained from patients diagnosed with bone and tissue malignancies (BTM) who had undergone haematopoietic stem cell transplantation (HSCT) and experienced aGVHD. Patients who experienced initial graft failure and individuals who underwent subsequent bone marrow transplantation were excluded. RESULTS: Total of 117 patients diagnosed with BTM underwent fully matched HSCT, including 76 (65%) males, and 41 (35%) females. The median age of the patients undergoing transplantation was 7.34±7.32 years and the donors' median age was 7.6±9.85 years. Among the donors, 53 (45.3%) were males and 64 (54.7%) were females. Gender disparity was observed in 46 (39.3%) instances as a female donor matched with a male recipient. A total of 106 individuals underwent bone marrow harvest (BMH); with 5 (4.3%) patients receiving peripheral blood stem cells (PBSC) and 6 (5.2%) patients receiving both BMH and PBSC. Acute GvHD was observed in 50 (42.7%) patients, including 30 (60%) males and 20 (40%) females. Grade I GvHD occurred in 32 (27.3%) individuals, Grade II GvHD in 16 (13.7%) patients, and Grade III GvHD in one (0.8%) patient. It had no statistically significant association with recipient/donor age, gender disparity, the source of the graft source, the dose of stem cells, or the presence of thymoglobulin (TG). CONCLUSION: Acute GvHD was observed in high frequency in Beta-thalassemia patients receiving morrow harvesting proportional to their gender distribution. Associated factors were GvHD prophylaxis measure, mucositis and, CMV reactivation. KEY WORDS: Beta thalassemia major patients, Acute graft versus host disease, Allogeneic haematopoietic stem cell.

Outcomes of Haematopoietic Stem Cell Transplantation in Beta Thalassemia Major with Fully Matched Parents as Donor.

OBJECTIVE: To determine the outcome of beta thalassemia major (BTM) patients undergoing haematopoietic stem cells (HSCT), with fully matched parents as donors vs. matched sibling donors (MSD). STUDY DESIGN: Observational Study. Place and Duration of the Study: Department of Clinical Haematology and Bone Marrow Transplantation Centre, Rawalpindi, Pakistan, from January 2013 to July 2023. METHODOLOGY: Group A consisted of BTM patients who underwent HSCT with fully matched siblings as donors, and Group B consisted of BTM patients who underwent HSCT with fully matched parents as donors. Study data included the age and gender of both recipients and donors, source and dose of stem cells infused, and stage and grades of acute and chronic graft versus host disease (GvHD). All patients received Myeloablative conditioning regimen (MAC). Data were collected to assess patients' demographics, response to HSCT, remission rate, disease free survival (DFS), relapse, and GvHD free survival (GRFS), and overall survival (OS). RESULTS: The mean age of the 54 patients was 5.90 ± 3.29 years. The mean TNC and CD34 doses were 4.99 + 1.13 and 5.42 + 3.70, respectively. Mean time for neutrophil engraftment in both groups was 14.88 + 4.51 days and platelets engraftment was 23.0 + 5.35 days. Most common cause of death was neutropenic sepsis followed by aGVHD. Seven patients had graft rejection. There was no significant association found between graft rejection with donor relation though graft rejection was higher in OS in this study was 70.4%. OS was equal in both groups. Disease free survival was superior in MSD (63%) than parent group (57.7%). CONCLUSION: Allogenic bone marrow transplantation with parents as donors in BTM patients yields outcomes comparable to those with matched sibling donors. This finding is especially relevant in regions like Pakistan, where donor registries and high-resolution HLA typing may be limited. KEY WORDS: Beta thalassemia major, Haematopoietic stem cell transplant, Post-transplant outcome.

Comparison of Steady-State Bone Marrow and GCSF-Primed Stem Cell Sources Used in Allogeneic Hematopoietic Stem Cell Transplantation.

OBJECTIVE: To compare donor graft characteristics and clinical outcomes in recipients of allogeneic heamatopoietic stem cell transplantation (HSCT) using GCSF primed bone marrow (GBM) and steady-state bone marrow (SBM) as stem cell sources. STUDY DESIGN: Observational study. Place and Duration of the Study: Department of Clinical Haematology, Armed Forces Bone Marrow Transplant Centre, Rawalpindi, Pakistan, from August 2018 to October 2020. METHODOLOGY: Eighty patients undergoing allogeneic HSCT were analysed. Among these, forty each received GBM and SBM from HLA identical siblings. Graft characteristics, such as total nucleated cells, CD34+ cell yield; clinical outcomes such as neutrophil and platelet engraftment, primary and secondary graft failure (GF), as well as the frequency of acute and chronic graft versus host disease (GvHD), were recorded and compared using the t-test, with significance at p <0.05. RESULTS: A statistically significant difference was observed in CD34+ dose with median dose 7.68 (p=0.002) but not in TNC dose with meadin dose 5 (p=0.86). Neutrophil engraftment occurred much more quickly with median of 13.43 days in the GBM than SBM group (p=0.025). While no statistically significant difference (p=0.89) in platelet engraftment was reported in both SBM and GBM. At the same time, patients with both GBM and SBM transplants showed a comparable ratio of acute to chronic GvHD and primary to secondary GF. CONCLUSION: GBM is associated with better CD34+ stem cell yield and quicker neutrophil engraftment in clinical outcomes. KEY WORDS: Granulocyte colony-stimulating factor, Bone marrow, Hematopoietic stem cell transplantation.

Incidence, management and outcome of Hepatic Veno-Occlusive disease /Sinusoidal Obstruction Syndrome after hematopoietic stem cell transplant in Thalassemia major patients: A prospective study of Pakistani BMT.

Objectives: Hepatic Veno occlusive disease (VOD), also known as sinusoidal obstruction syndrome (VOD/SOS), is a post-transplant life threatening complication. In this study, we aimed to discuss the incidence, management and outcome of VOD in post allogenic transplant patients of beta thalassemia major (BTM). Methods: A prospective study was conducted in Armed Forces Bone Marrow Transplant Center, between 2001-2022. A total of 385 fully Human Leucocyte Antigen (HLA) matched BTM patients, with Ursodeoxycholic acid for prophylaxis, were included in the study. Incidence of VOD was calculated through cumulative incidence estimates. Chi square test and Mann Whitney test were used to compare discrete and continuous variables respectively. VOD was diagnosed and graded according to European Society for Blood and Marrow Transplantation EBMT Pediatric diagnostic criteria. Risk factors for VOD were grouped as recipient, transplant and donor related. Univariate analysis was performed by log-rank test. All patients who developed VOD were managed primarily with fluid restriction and strict input output monitoring. Statistical analyses were performed using SPSS v 25.0. Results: Out of 385 transplant patients, forty developed VOD. Median time from date of transplant till onset of VOD was 14 days (range 6-30). Cumulative incidence of all grade VOD was 10.39% (95% CI, 7-14). Eleven out of 40 patients who developed VOD died. Cumulative incidence of Transplant related mortality (TRM) for patients with and VOD was 20.5% (95% CI, 16.6-25.1) vs 27.5% (95% CI, 16.1-42) (p value 0.318) respectively. Among risk factors, age of recipient and fibrosis (p value of 0.04 and 0.000 respectively) were found to be significantly associated with VOD. Conclusions: Careful selection of transplant candidates before transplant can help reduce the incidence of VOD.

Oral Mucositis in Patients Undergoing Hematopoietic Stem Cell Transplantation.

OBJECTIVE: To determine the factors affecting the frequency and severity of oral mucositis are following hematopoietic stem cell transplantation. STUDY DESIGN: Descriptive study. Place and Duration of the Study: Armed Forces Bone Marrow Transplant Centre Rawalpindi, from September 2020 to February 2022. METHODOLOGY: Patients who underwent allogenic stem cell transplantation were enrolled. Patients were analysed based on history and examination for oral mucositis (OM) as per the WHO mucositis scale, from the start of conditioning chemotherapy till discharge, total duration of mucositis and type of medication were noted. Its association with risk factors like age, gender, conditioning chemotherapy, methotrexate (MTX) for GVHD prophylaxis, and prior history of irradiation was determined. RESULTS: Mean age of the 72 transplant recipients was 21.9 ± 14 years, with 48 males and 24 females. The common underlying diseases were beta-thalassemia major (30.6%, n=22), acute lymphoblastic leukaemia (n=15, 20.8%), aplastic anaemia (n=10, 13.9%), and multiple myeloma (n=8, 11.1%). The frequency of mucositis in those aged under 15 years was 79.3% (n=23) and in those older than 15 years was 74.4% (n=32). Frequency of mucositis was statistically significant in patients who received myeloablative conditioning regimen (85% vs. 20%, p <0.01), and who had prophylactic. MTX (91% vs. 48%, p<0.01) and who had prior craniospinal (CSI) radiation (100% vs. 70.2%, p=0.01). There was no statistical significance between stem cell dose (CD34/TNC) and mucositis. Severity of mucositis was significantly greater in Allogenic vs. auto HSCT (p=0.04). All the patients with mucositis required analgesics for pain management. CONCLUSION: Oral mucositis is a common but potentially debilitating complication of stem cell transplant, requiring opioid analgesia in a significant number of cases. Myeloablative conditioning, prophylactic MTX, and prior CSI are significantly associated with mucositis in transplant patients. KEY WORDS: Hematopoietic stem cell transplantation (HSCT), Oral Mucositis, Myeloablative conditioning, Methotrexate, Analgesia.

Cytomegalovirus Infection Post-Allogeneic Stem Cell Transplantation: Experience from a Country with High Seropositivity.

Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Limited data are available from developing countries regarding the frequency of CMV infection and treatment outcomes. We enrolled 230 consecutive patients undergoing allogeneic HSCT for various hematologic disorders at the Armed Forces Bone Marrow Transplant Center/National Institute of Blood And Marrow Transplant between February 2017 and December 202. CMV reactivation post-HSCT was monitored weekly starting at day +30 and continuing until day +100, and preemptive antiviral therapy was administered to prevent CMV disease in all HSCT recipients with ≥2000 CMV copies/mL. The median age of the study cohort was 9.5 years (range, .6 to 53 years), and the male:female ratio was 2.4:1. The most frequent indication for HSCT was beta thalassemia major (36.1%), followed by aplastic anemia (23.9%). Malignant disorders constituted 20% of all the patients. Pretransplantation CMV seropositivity was 99.1% for the recipients and 99.5% for the donors. CMV infection was seen in 66.1% of the patients, and the median time to CMV DNAemia was 36 days (range, 12 to 95 days). Preemptive antiviral therapy was administered to 140 patients with a CMV viral load ≥2000 copies/mL (61%). In multivariate analysis, patient age >12 years, steroid administration, and use of mycophenolate mofetil with or without post-transplantation cyclophosphamide was associated with the greatest probability of CMV reactivation. Overall survival was 97.4% in patients without CMV reactivation, compared to 80.3% in those with CMV reactivation (P = .001). Event-free survival was 78.7% in the total study cohort, including 89.7% for patients without CMV reactivation and 73% for patients with CMV reactivation (P = .003). Our study is the first from this region to explore the frequency of CMV seropositivity and CMV infection, risk factors for CMV reactivation, and outcomes of antiviral therapy in HSCT recipients.

Haematopoietic Stem Cell Transplantation (HSCT) for Primary Immune System Disorders in Children: A Single Centre Experience.

OBJECTIVE: To determine the outcomes of allogeneic HSCT in children with primary immune system disorders (PID). STUDY DESIGN: Descriptive Cross-sectional study. Place and Duration of the Study: Armed Forces bone marrow transplant centre / National Institute of Bone Marrow Transplant (AFBMTC / NIBMT), Rawalpindi, Pakistan, from October 2012 to December 2021. METHODOLOGY: Data of all cases undergoing HSCT for immune system disorders were analysed for variables affecting outcome and overall survival in the first 180 days after allogeneic HSCT. All patients presenting to AFBMTC / NIBMT with PID, age <12 years. Patients with organ dysfunction secondary to repeated infections were excluded from the study. Data of all patients and their donors undergoing HSCT for immune system disorders were analysed for variables affecting outcome and overall survival in the first 180 days after allogeneic bone marrow transplant. Neutrophil engraftment was defined as absolute neutrophil count ≥0.5 × 109/L for 3 consecutive days, while platelet engraftment as platelet count ≥20 × 109/L without platelet transfusion for one week. Overall survival (OS) was taken as time from the date of HSCT till day + 180 post-transplant. RESULTS: A total of 42children including 29 boys and 13 girls underwent HSCT for PID. The mean age was 2.1±2.8 years. Underlying diagnosis was haemophagocytic lymphohistiocytosis (HLH), severe immune deficiency (SCID), leukocyte adhesion defect (LAD), X-linked agammaglobulinemia, chronic granulomatous disease (CGD) and Job's syndrome in 18 (42.9%), 16 (38.1%), 3(7.1%), 2 (4.8%), 2 (4.8%) and 1 (2.4%) patients respectively. Thirty-one (73.8%) children had fully HLA-matched donors while 11 (26.2%) had haplo-matched donors. Major immediate post-transplant complications were febrile neutropenia, mucositis and SOS/VOD in 31 (73.8%), 9 (21.4%) and 4 (10.0%) cases, respectively. Eight (19.0%) had CMV reactivation, acute GVHD was seen in 17 (40.4%) cases, while 1 (2.3%) case had chronic GVHD. Twelve (28.6%) patients died, out of which 5 had graft failure, 3 had VOD, 2 had pneumonia, 1 had severe GVHD, and 1 died due to seizures. Overall survival (OS) in this study was 71.4% with survival reaching up to 80.6% in fully matched HSCT. CONCLUSION: HLH and SCID were the commonest immune disorders requiring HSCT. Graft failure leading to neutropenic sepsis was the commonest cause of mortality. OS was better in fully matched HSCT as compared to haplo-identical HSCT. KEY WORDS: Immune deficiency, Severe combined immunodeficiency, Haematopoietic stem cell transplantation.

Response To Immunosuppressive Therapy In Patients Of Acquired Aplastic Anaemia: A Single Center Experience From A Developing Country.

Background: Aplastic Anaemia (AA) is characterized by pancytopenia and hypocellular marrow. Immunosuppressive therapy (IST) SHOWS impressive haematological response; however, risk of relapse and clonal evolution persists. The objective of the study is to assess response to IST in patients with aplastic anaemia. Methods: A retrospective single centre study at AFBMTC / NIBMT for patients of acquired AA was conducted from January 2005 to December 2019.Inclusion criteria included diagnosed cases of acquired AA receiving IST for at least 12 weeks and age >2 years. IST included cyclosporine (CsA) alone, CsA + androgens, CsA + rabbit anti thymocyte globulin (rATG), CsA + horse anti thymocyte globulin (hATG). Primary outcome measure was response to IST; secondary outcome measure was overall survival (OS). Results: A total of 513 patients received IST. Median age was 23 years (range 2-97 years). In study cohort, 155 (30.2%) patients responded to the IST, 63 (12.3%) achieved complete response (CR) while 92 (17.9%) achieved partial response (PR). The ORR of CsA in NSAA, SAA and VSAA was 52.6%, 28.10% and 10% respectively; whereas ORR of CsA + rATG in NSAA, SAA and VSAA was 50%, 35.1% and 22.5% respectively. OS was 38% at a median follow up of 36 months. There was a significant difference in the survival distributions of different treatment modalities (p=0.016). Median survival time 60 months (CsA), 9 months (CsA+ androgens) and 39 months (CsA+ rATG/hATG.) . Conclusion: In resource constrained settings, single agent CsA remains a reasonable alternative with modest activity and acceptable side effect profile.

Allogeneic hematopoietic stem cell transplant in rare hematologic disorders: a single center experience from Pakistan.

Management of rare hematological disorders pose unique diagnostic and therapeutic challenges due to unusual occurrence and limited treatment options. We retrospectively identified 45 patients receiving matched related donor transplant for rare hematological disorders from 2006 to 2019. Patients were divided into two groups (1) malignant and (2) non malignant. The malignant disorder group included four patients while the nonmalignant group included 41 patients divided into immune dysregulation (n = 23), bone marrow failure (n = 10), metabolic (n = 5), and bleeding diathesis (n = 3). Twenty-six (57.8%) patients received myeloablative conditioning (MAC) and 16 (35.6%) received reduced intensity conditioning (RIC), while 3 (6.6%) patients with severe combined immunodeficiency received stem cell infusion alone without conditioning. The cumulative incidence (CI) of grade II-IV acute GVHD (aGVHD) was 39.1% (n = 18) and chronic GVHD (cGVHD) 15.2% (n = 7). There was no primary graft failure while CI of secondary graft failure was 9%. Overall survival (OS) and disease-free survival (DFS) was 82.2% and 77.8% respectively. Group wise OS was 75% in the malignant group, 82.6% in the immune dysregulation group, 80% in patients with metabolic disorders and bone marrow failure, while 100% in patients with bleeding diathesis. This retrospective analysis shows that hematopoietic stem cell transplant can be a feasible treatment option for rare hematological disorders.

Allogeneic hematopoietic stem cell transplantation in aplastic anemia: current indications and transplant strategies.

Treatment options for newly diagnosed aplastic anemia (AA) patient includes upfront allogeneic hematopoietic stem cell transplant (HSCT) or immunosuppressive therapy (IST). With recent advances in supportive care, conditioning regimens and post-transplant immunosuppression the overall survival for HSCT approaches 70-90%. Transplant eligibility needs to be assessed considering age, comorbidities, donor availability and probability of response to immunosuppressive therapy (IST). Upfront HSCT should be offered to children and young adults with matched related donor (MRD). Upfront HSCT may also be offered to children and young adults with rapidly available matched unrelated donor (MUD) who require urgent HSCT. Bone marrow (BM) graft source and cyclosporine (CsA) plus methotrexate (MTX) as graft versus host disease (GVHD) prophylaxis are preferable when using anti-thymocyte globulin (ATG) based conditioning regimens. Alemtuzumab is an acceptable alternative to ATG and is used with CsA alone and with either BM or peripheral blood stem cells (PBSC). Cyclophosphamide (CY) plus ATG conditioning is preferable for patients receiving MRD transplant, while Fludarabine (Flu) based conditioning is reserved for older adults, those with risk factors of graft failure and those receiving MUD HSCT. For haploidentical transplant, use of low dose radiotherapy and post-transplant cyclophosphamide has resulted in a marked reduction in graft failure and GVHD.

Single-Agent Cyclosporine for Graft-versus-Host Disease Prophylaxis in Patients with Acquired Aplastic Anemia Receiving Fludarabine-Based Conditioning.

Cyclosporine (CsA) combined with short-course methotrexate is considered standard-of-care graft-versus-host disease (GVHD) prophylaxis for patients with severe aplastic anemia (AA) who undergo transplantation using cyclophosphamide (Cy) plus anti-thymocyte globulin (ATG) conditioning. However, there is no consensus on optimal post-transplant GVHD prophylaxis for patients undergoing matched related donor (MRD) transplantation using fludarabine (Flu)-based conditioning. We conducted a single-center retrospective analysis of patients with acquired AA (n = 106) undergoing MRD transplantation from July 2007 through January 2019. All patients received Flu-Cy-ATG conditioning and single-agent CsA as GVHD prophylaxis. Median age of the study cohort was 20 years (range, 3 to 52) and male to female ratio was 3.8:1. Median time from diagnosis to transplant was 11.5 months (range, 2.8 to 62). Graft source was bone marrow harvest in 71 (68%), combined bone marrow and peripheral blood stem cells in 34 (31%), and peripheral blood alone in 1 (1%) patient. Cumulative incidence of neutrophil engraftment at day 28 was 93.4% (95% confidence interval [CI], 87.3% to 97.1%) while that of platelet engraftment at day 100 was 90.5% (95% CI, 84% to 96%). Cumulative incidence of primary graft failure at day 28 was 6.6% (95% CI, 4% to 8%) while secondary graft failure occurred at a median of 190 days (range, 90 to 415) at a cumulative incidence of 3.7% (95% CI, 2% to 5%). Cumulative incidence of grade II to IV acute GVHD at day 100 was 3.8% (95% CI, 1.4% to 9.9%), while a 1-year probability of chronic GVHD was calculated as 7.5% (95% CI, 2.6% to 15%). Median follow-up post-transplant was 61 months (range, 6 to 144). Overall survival was 84.9%, disease-free survival was 80.2%, and GVHD-free relapse-free survival was 76.3%. This study indicates that single-agent cyclosporine is a feasible option for GVHD prophylaxis in MRD hematopoietic stem cell transplantation using Flu-Cy-ATG conditioning and is associated with very low rates of acute and chronic GVHD.

Comparison of Conventional Cyclophosphamide versus Fludarabine-Based Conditioning in High-Risk Aplastic Anemia Patients Undergoing Matched-Related Donor Transplantation.

Allogeneic stem cell transplant for high-risk aplastic anemia (AA) yields inferior results using conventional cyclophosphamide (CY)-based conditioning. The use of fludarabine (Flu)-based regimens has resulted in improved outcomes in high-risk patients. Limited data are available comparing these two conditioning regimens in such patients. We retrospectively analyzed 192 high-risk patients undergoing matched-related donor transplantation from July 2001 to December 2018. The median age was 19.5 (2-52) years. Patients were divided into 2 groups, Cy200 anti-thymocyte globulin (ATG)20 (Gp1 n = 79) or Flu120-150 Cy120-160 ATG20 (Gp2 n = 113). The risk of graft failure was significantly higher in Gp1, and the majority occurred in patients with >2 risk factors (p = 0.02). The incidence of grade II-IV acute graft versus host disease (GVHD) and chronic GVHD was not significantly different between the two groups. The overall survival (OS) of the study cohort was 81.3 %, disease-free survival (DFS) 76.6 % and GVHD-free relapse-free survival (GRFS) was 64.1%. DFS and GRFS were significantly higher in Gp2 as compared to Gp1: DFS 84.1% versus 68.4 % (p = 0.02), GRFS 77.9% versus 54.4% (p = 0.01), respectively. We conclude that Flu-based conditioning is associated with superior OS, DFS and GRFS as compared to the conventional Cy-based regimen in high-risk AA.

Outcome of Fludarabine-Based Conditioning in High-Risk Aplastic Anemia Patients Undergoing Matched Related Donor Transplantation: A Single-Center Study from Pakistan.

Despite excellent transplant outcomes of aplastic anemia (AA) in developed countries, management in developing countries is challenging because of delay in the diagnosis, use of family donors for transfusions, and higher infection risk pretransplant. These factors can lead to allo-immunization, increased risk of graft failure, graft-versus-host disease (GVHD), and transplant-related mortality, leading to unfavorable outcomes. Conventional cyclophosphamide (Cy) and antithymocyte globulin (ATG) are associated with inferior overall survival in such high-risk patients. We conducted single-center retrospective analysis of high-risk AA patients (N = 147) enrolled consecutively and undergoing matched related donor transplant from March 2002 through October 2018. We included high-risk AA patients receiving fludarabine (Flu)-based conditioning. Median patient age was 20 years (range, 3 to 52). The median time from diagnosis to transplant was 11 months (range, 3 to 63). High-risk features included age ≥ 20 years in 55.8% of patients (n = 82), disease duration more than 3 months in 95 % (n = 140), RBC concentrates transfusions > 20 in 79.6% (n = 117), random donor platelet transfusion > 50 in 64.6% of patients (n = 95), and second hematopoietic stem cell transplant (HSCT) in 7.4% (11). We divided patients into 2 groups based on different conditioning regimens. Flu group 1 (Flu1) received Flu 120 to 150 mg/m2, Cy 120 to 200 mg/kg, and ATG 20 mg/kg, and Flu group 2 (Flu2) was given Flu 150 mg/m2, Cy 300 mg/m2, and ATG 20 mg/kg. Bone marrow stem cells were used as graft source in 97% of patients (n = 144) (alone in 52% and with peripheral blood stem cells in 45%). Cyclosporine alone was used for GVHD prophylaxis in 75% (n = 110) and cyclosporine plus methotrexate in 25% (n = 37). Median total nucleated cell dose was 5 × 108/kg. Median days for neutrophil engraftment was 13 (range, 10 to 20) and platelet engraftment 20 (range, 14 to 43). Day 100 mortality was 7.5% (n = 11). Sustained successful engraftment was achieved in 87.8% of patients (n = 129). Most graft failures (40%) occurred in Flu2 conditioning (P = .000) and in patients with >2 risk factors (P = .000). Overall incidence of acute and chronic GVHD was 11.6% (n = 17) and 12.9% (n = 19), respectively, in Flu1 and Flu2 groups. Overall survival (OS), disease-free survival (DFS), and GVHD-free relapse-free survival (GRFS) was 83.7%, 78.2%, and 70.7%, respectively. A trend toward improved OS was observed in patients receiving Flu1 conditioning but was statistically nonsignificant (P = .256), whereas DFS and GRFS were significantly better in Flu1 versus Flu2 (P = .004 and .001, respectively). When stratified per number of risk factors (age > 20, RBC concentrate > 20 or platelet > 50 random, duration > 3 months, previous HSCT), OS and DFS decreased significantly with increasing number of risk factors (P = .000 and .001, respectively). Patients are able to tolerate Flu-based conditioning well with lower rates of rejection and excellent long-term survival in high-risk AA patients. Cyclosporine alone as GVHD prophylaxis and marrow source stem cells as graft source are preferable options. Use of Flu plus low-dose Cy conditioning is associated with inferior survival outcomes. A randomized trial of Flu-based versus conventional Cy-containing conditioning would be helpful in establishing a standard of care conditioning regimen in high-risk AA patients.