We used a novel NF-08-TM transplant protocol based on intravenous busulfan, cyclophosphamide, fludarabine, and thiotepa in 82 consecutive patients with ␤-thalassemia major (TM), including 52 with allogeneic peripheral blood stem cell transplantation (PBSCT) from unrelated donors (UDs) with well-matched human leukocyte antigens and 30 with hematopoietic stem cell transplantation (HSCT) from matched sibling donors (MSDs). The median age at transplantation was 6.0 years (range, 0.6-15.0 years), and the ratio of male-to-female patients was 56:26. The median follow-up time was 24 months (range, 12-39 months). The estimated 3-year overall survival and TMfree survival were 92.3% and 90.4% in the UD-PBSCT group and 90.0% and 83.3% in the MSD-HSCT group. The cumulative incidences of graft rejection and grades III-IV acute graft-versus-host disease were 1.9% and 9.6%, respectively, in the UD-PBSCT group and 6.9% and 3.6%, respectively, in the MSD-HSCT group. The cumulative incidence of transplant-related mortality was 7.7% in the UD-PBSCT group and 10.0% in the MSD-HSCT group. In conclusion, UD-PBSCTs using the welltolerated NF-08-TM protocol show similar results to MSD-HSCTs and can be used to treat ␤-thalassemia patients in the absence of MSDs. (Blood. 2012;120(19): 3875-3881)

OBJECTIVE: Pre-transplant chemotherapy can control progression of primary disease, alleviate disease and improve disease-free survival after transplantation in juvenile granulocyte leukemia (JMML).Methylation abnormalities play an important role in the development of JMML. This study was to explore the effectiveness of induction regimen including decitabine ,cytarabine and fludarabine before transplantation and to explore the affection to transplantation in JMML. METHODS: A retrospective analysis of the remission and survival of 33 children with JMML before and after stem cell transplantation in the Department of Pediatrics of Nanfang Hospital from 2014.2 to 2019.7. There were fourteen girls and 19 boys, median diagnosis age 23 months(2m-10 years old). Median white blood cell count,median hemoglobin level,median platelet count( WBC) was 29.3G/L (6.29-158.66G/L); 83g /L(41-113g/L,); 27.17G / L(4-431G / L) respectively. Median Hemoglobin F level was 34.16%( 1.56-78%). Median spleen level under the costal margin was 5cm(0-13.3cm); Median liver under the costal margin was 3.9 cm(0 -8.9 cm) .There were 26 cases with the pulmonary involvement (26/33, 78.8%). The original blast cells in bone marrow were 0-8.8%, with a median of 4.5%.Mutant genes including: 2 cases of KAS, 9 cases of NF1, 2 cases of NRAS, 16 cases of PTPN11, and 4 cases without common JMML gene .The first course of treatment after diagnosis is 20 mg/m2 × 5 days of decitabine. The second course of treatment is DA: decitabine 20 mg/m2 × 5 days + cytarabine 100 mg/m2 × 5 days or A-3V regimen: Ara-C 100 mg/m2/d CIV×7 days+Etoposide 100 mg/m2/d ×5 days+Vincristine 1.5 mg/m2/d ×1 day. The third course of treatment is decitabine 20 mg/m2 × 5 days,then FLAG regimen: Fludarabine 30mg / m2 × 5 days, Ara-C 1 g / m2 × 5 days, G-CSF 5μg / Kg × 6 days. Single drug of decitabine 20 mg/m2 × 5 days was adminstered 1-3 times per monthly during the period of waiting for transplantation. Comprehensive assessment was performed before transplantation. Survival outcomes were analyzed by Kaplan-Meier curves. RESULTS: At least 3 courses of chemotherapy were completed in 33 cases, including 1-5 courses of decitabine.The bone marrow was evaluated in 31 patients before transplantation: 12 patients got complete remission(CR) and 19 patients got partial remission(PR) .Peripheral blood evaluation: 23 cases achieved WBC CR; 17 cases achieved platelet CR, 6 cases achieved platelet PR, 7 cases had no improvement. Eighteen cases of spleen were evaluated, of which only 3 cases were CR, 13 cases were PR, and 2 cases did not improve. Overall assessment, only 1 case achieved CR before transplantation, 1 case did not improve, and 31 cases achieved PR .Allogeneic hematopoietic stem cell transplantation was performed in 33 cases, including 3 cases of nonrelated peripheral blood hematopoietic stem cell transplantation(PB HSCT), 30 cases of complementary transplantation (haploid identical PB HSCT plus non-related cord blood transplantation). The median follow-up time after transplantation was 22m(3-63m).There was no death in the period of chemotherapy before transplantation. Four patients relapsed after transplantation, and One patient died of transplantation related death. Three years EFS was 80.6%. Conclusion: Pre-transplant chemotherapy based on regimen of decitabine + cytarabine + fludarabine is safe, effective and feasible. The response rate of treatment is 97.0%, although the complete remission rate before transplantation is low, most of them are partial remission, but the disease-free survival after non-related HSCT or complementary transplantation could reached to 80.6%. These results indicated that pre-transplant chemotherapy based on regimen of decitabine + cytarabine + fludarabine was benefit to improved the survival of children with JMML after HSCT. Figure 1 Disclosures No relevant conflicts of interest to declare.

Background: Many Chinese patients with hematologic disease, who need allogeneic hematopoietic stem cell transplantation(HSCT) commonly lack an HLA matched sibling since a Chinese family often has a single child due to Chinese one-child policy in the past 10years. As an alternative option, unrelated HSCT is the feasible option for the patients without matched related donors (MRD). Many study have found that thalassemia-free survival (TFS) was approximately 90% in unrelated donor HSCT (UDT) for TM patients. Donor selection is one of key factors for better outcomes after hematopoietic stem cell transplantation (HSCT). Choosing the most suitable donors for TM patients can be challenging to physicians and search coordinators. It is shown that increased donor age is associated with high mortality. However, outcomes of donor factors such as age, sex, CMV status, ABO type, matching of HLA loci and female donor pregnancy history for TM patients have rare been taken into account and evaluated. Aims: The aim of this study was to develop and validate the principal of donor selection and to evaluate the impact of donor characteristics on survival outcomes especially in case of mismatch unrelated donor. Patients and Methods: Between December 2008 to December 2018,274 TM patients with a median age of 6 years (2-23) had no suitable matched related donor performed an unrelated HSCT. 189 patients have been typed by high resolution (HR) HLA typing for HLA-A/B/C/DRB1 loci, at the start of the donor's search process and 85 typed by high resolution (HR) HLA typing for HLA-A/B/C/DRB1/DQB1 loci. Patients, donors and transplant characteristics are summarized in Table 1 Result: 217 (79.2%) recipient were HLA full matched (FM) with donors, 51 (18.6%) of recipient-donor pairs were HLA one locus mismatched (mm) and 6 (2.2%) two loci mm . Statistically significant differences were observed in overall survival (OS) and thalassemia-free survival (TFS) among full matched group, one loci mm matched group and two loci mm group, the corresponding OS, TFS were 95.4%,88.2%,66.7% (P=0.010,shown in Figure one) and 93%,88%,66.7% (P=0.089) respectively. Risks for cGVHD were higher in recipient-donor HLA-mm transplantation, particularly significant in two loci mm transplant,P=0.000(Figure2). ABO compatibility did not affect OS and TFS (94.8 vs. 93%,P=0.572 and 94.8% vs. 90.2, P=0.190 respectively in ABO matched group and ABO mismatched group), whereas ABO mismatched was associated with higher rate of graft rejection (GR) although not statistically significant ( 0% vs. 4.3%, P=0.069). Notably, donor age was significantly associated with worse survival. Both OS and TFS for donor older than 40 years old was significantly worse than those <40 years old(94.6%vs.85% P=0,051)and (93% vs.82%, P=0.042) respectively( Figue3). Interestingly, previous pregnancy of female donors prior to donation had an impact on acute GVHD, parous female donors resulted in a significantly increased risk of aGVHD (31.8 vs. 13.1%,P=0.024) . However, donor other characteristics such as sex, parity, and cytomegalovirus serostatus were not associated with survival . For CMV- recipients, a CMV+ donor was not significantly associated with an increase in OS or TFS (92.7 vs. 93.3%, P=0.998, P=0.998 and 90.5% vs. 93.3%;P=0.601 respectively). Conclusion:Donor age and donor-recipient HLA match are important when selecting unrelated donors. Transplants from donors older than 40 years old should probably be avoided. Younger donors associates with better overall survival and lower rates of acute and cGVHD. When selecting unrelated donors, avoidance of parous female donors if possible as to avoid high incidence of aGVHD. Other donor characteristics such as sex, parity, and cytomegalovirus serostatus were not associated with survival. ABO mismatching (any type: major, minor or bidirectional) was not associated with OS, TFS or GVHD but related to graft rejection. In the future we will observe ABO mismatch among donors and recipients on engraftment time. Disclosures No relevant conflicts of interest to declare.

Background: Hematopoietic stem cell transplantation (HSCT) is the most effective curative option for patients with thalassemia major(TM). Early post-transplant mixed chimerism (MC) has known to be a predictor of secondary graft rejection. However, the impact of the persisting mixed chimerism on transplant outcome remains controversial. Recently Thiotepa(TT) has been decreased to reduce toxicity.There was no data available on reduced intensity conditioning on mixed chimersim in a large group of patients with thalassemia to date. Aims: To assess risk factors of mixed chimerism and to evaluate possible correlations between mixed chimerism and the development of complications after HSCT, in terms of graft versus host disease (GVHD) development, OS, TFS and GR. Patients and methods: From December2008 until December 2019, 618 patients with TM underwent HSCT at our center with median age of 6 (1-23) and median follow up time of 70 months(1-135), from HLA-identical sibling donors (SD) (n=212; 34.3%), unrelated donors (UD, n=313; 50.6%),sibling Cord blood(CB, n=49,7.9%)and parent donors (PD, n=44,7.1%). Source of graft were 538 (87.1%) from peripheral stem cells, 32(5.2%) from bone marrow and 48(7.8%)from sibling cord blood. Cy+Bu+Flu+TT+ATG conditioning regimen was used in 416 pts while a reduced conditioning regimen Cy+Bu+Flu+ATG was used for 167pts and Cy+Bu+Flu for the other 35 pts. Results Overall Survival (OS), Thalassemia-Free survival (TFS), Transplantation-related mortality (TRM) and graft rejection (GR) for the entire group were 94.8%, 92.7% ,5.2% and 2.4% respectively. MC was presented in 70 pts with 52 male and 18 female, defined as the presence of &gt;5% residual recipient cells. Cumulative incidence of MC was 12.4% (Figure1). 5 pts had secondary graft failure and another 5 patients persisting MC post-transplant refractory to DLI following a second HSCT. There were two deaths ineffective to DLI and one die of idiopathic pneumonia and one of hemolytic uremic syndrome. The median MC present time was 4 months (1-59 months).No significant difference was observed in OS and Thalassemia-Free survival (TFS) between MC and PC pts. The cumulative probability of OS, TFS between MC pts and FC pts was 97.1% vs. 94.4% (P=0.343) and 89.6% vs. 93.2% (P=0.272). However, the incidence of MC was significantly associated with the development of graft failure/rejection. Graft failure occurred in 5 pts in the MC group vs.7 pts in the full donor chimerism (PC) group, the corresponding incidence were 7.6% vs. 1.6 % respectively. (P =0.001, Figure 2). Acute GVHD incidence was much lower in MC pts than in PC pts (2.9% vs. 12.7%, P=0.022, Figure 3 A), whereas MC pts had significantly higher chronic GVHD(16.8% vs. 4.2%, P=0.000 Figure 3 B). 2 of 70 MC pts developed I-II aGVHD. No MC pts develop II-IV aGVHD. MC patients were unlikely to have severe acute GVHD. MC was associated with an increased risk of chronic GVHD, mostly were DLI derived Patients receiving stem cells from cord blood of matched sibling donors had a high risk of MC.MC incidence of stem cell source from peripheral blood(PB), bone marrow(BM), cord blood (CB)were 10.6%, 10%, 34.2% respectively.(P=0.000, Figure 4). Unrelated donors had a lower risk of MC than sibling donors. Incidence of MC from unrelated donors was 9.5% vs. 16.1% from sibling donors (P=0.007, Figure 5) Intravenous Thiotepa (TT) in combination with Busulfan (Bu) , cyclophosphamide (Cy) anti-thymocyte globulin(ATG) on HSCT could reduce the risk of MC. The corresponding incidence of MC in Cy+Bu+Flu+TT+ATG, Cy+Bu+Flu+ATG, Cy+Bu+Flu conditioning regimen were 9.2%,15.9%,40.9% resepectively(P=0.000, Figure 6). There was also a significant difference in chimerism based on donor-recipient gender pairing (P = 0.041): male grafts into male patients having the greatest risk of MC and female grafts into female patients having the least. Patients who under 9 years old had a higher risk of MC than that of pts&gt;9 years old (P=0.018, Figure 7), Summary: Our results show that patients who presented mixed chimerism showed a similar post-transplant outcome in OS and TFS but was associated with higher risk of graft failue.Patients receiving stem cells from CB had a high risk of MC than from PBSC. Reduced nonmyeloablative approach capable of achieving allogeneic mixed hematopoietic chimerism. Our data suggests that Cy+Bu+Flu+TT+ATG is a preferred conditioning regimenfor TM patients could reduce the risk of mixed chimerism. Disclosures No relevant conflicts of interest to declare.