scholarly journals Fludarabine Melphalan Versus Fludarabine Treosulfan As Reduced Intensity Conditioning Regimens in Allogeneic Hematopoietic Stem Cell Transplant - a Retrospective Analysis

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4493-4493
Author(s):  
Akanksha Chichra ◽  
Lingaraj Nayak ◽  
Rushabh Kothari ◽  
Siddhesh Arun Kalantri ◽  
Avinash Bonda ◽  
...  

Introduction Allogeneic hematopoietic stem cell transplantation (AHSCT) has evolved as a curative therapy for various hematological malignancies. Regimen-related toxicity and transplant-related mortality (TRM) preclude the use of myeloablative conditioning (MAC) regimens in older and unfit patients. Reduced intensity conditioning (RIC) regimens have enabled AHSCT in such patients. There is a recent rise in use of RIC regimens even in younger patients in view of decreased toxicity and equal efficacy as reported in some studies. Fludarabine + Melphalan (FM) and Fludarabine + Treosulfan (FT) are 2 such regimens. There are no prospective randomised comparisons between these regimens. We retrospectively analysed these 2 regimens for toxicities and outcomes. Methods This is a retrospective single centre analysis of all consecutive patients with haematological cancers who received either FM or FT from April 2008 to December 2018. The entire cohort was divided into two groups - Matched Sibling Donor (MSD)/Matched Unrelated Donor (MUD) and Haploidentical (Haplo) transplants for analysis. We compared patient characteristics, toxicities and outcomes in both the groups based on conditioning regimen. The FT regimen consisted of fludarabine (30 mg/m2 on days − 6 to − 2) combined with treosulfan (12-14 gm/m2 on days − 6 to − 4) with or without 2 Gy TBI on day-1. The FM regimen consisted of fludarabine (30 mg/m2 on days − 7 to − 3) combined with melphalan (140 mg/m2 on day -1).Prophylaxis for GVHD consisted of calcineurin inhibitor (CNI) plus methotrexate (MTX)or mycophenolate mofetil (MMF) in MSD/MUD. Rabbit ATG (2.5-5 mg/kg) was used for MUD. Haplo transplant patients received post-transplant cyclophosphamide with CNI and MMF. Comorbidities were scored according to the HCT-CI. Disease Risk Index(DRI) and EBMT score were recorded for all patients. Neutrophil (NE) and platelet engraftment (PE) were defined as per standard criteria. Early toxicity after AHCT was graded according to CTCAE version 4. Total parenteral nutrition (TPN) was used in patients as per the physician's discretion. Acute GVHD and chronic GVHD were recorded according to standard criteria. All patients underwent chimerism studies at day 15, 30 and then monthly for 1 year. Mixed chimerism was defined as > 5% to < 95% donor chimerism. The toxicities in various arms were compared by Chi-square test or Fisher exact test, while OS was calculated by Kaplan Meier method and the survival probabilities were compared using log-rank test. Competing risk analysis was used to calculate cumulative incidence of relapse and TRM. Results The study included 138 patients, 98 males and 40 females. The diagnoses were AML- 53, ALL- 30, MDS/MPN- 49 and lymphoma -6. Patient characteristics are outlined in Table 1. MSD/MUD transplants were 105 (FM- 94; FT-11); 33 were Haplo (FM-17; FT-16) transplants. PBSC was the stem cell graft in 136 (99%) patients. In both MSD/MUD and Haplo groups, there were no significant differences in median age, gender, pre transplant CMV status, HCT-CI and EBMT score between the two conditioning regimens. In MSD/MUD group, significantly more patients had high/very high DRI in FT arm (45% vs 17%; P=0.056) Comparison of engraftment and toxicity variables of both FM and FT arms are outlined in Table 2. In MSD/MUD group, 44 (47%) patients in FM arm had grade 3/4 oral mucositis compared to 1 (9%) in FT arm (P=0.02). Corresponding numbers were 7 (41%) and 1 (6%) in Haplo group (P=0.039). Grade 3/4 diarrhoea was higher in the FM vs FT arm of Haplo group (41% vs 6%; P=0.039) but not in the MSD/MUD cohort. More patients received TPN in the FM arms of both MSD/MUD and Haplo groups (Table 2). Incidence of grade III-IV acute GVHD was higher in FT vs FM in MSD/MUD group (27% vs 17%; P=0.04). The median follow up of entire cohort was 4.8 years. The OS (figure 1) at 5 years was 62% in FM arm of MSD/MUD group vs 53% in FT arm (P=NS). Similarly OS (figure 2) at 5 years was 41% and 28 %( P=NS) in FM and FT arms respectively of Haplo group. The cumulative incidence of TRM and relapse at 2 years were not different in FM and FT arms of both MSD/MUD and Haplo groups (Table 2). Conclusion Grade 3 and 4 oral mucositis and diarrhoea were significantly less with FT than FM in both MSD/MUD and Haplo groups. FT provided comparable outcomes to FM in the MSD / MUD group in spite of having higher proportions of patients with high / very high DRI. Prospective randomised studies are required to compare various RIC regimens. Disclosures No relevant conflicts of interest to declare.

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 159-159 ◽  
Author(s):  
Ronald M. Sobecks ◽  
Meighan M. Gallagher ◽  
Medhat Askar ◽  
Michael D. Haagenson ◽  
Tao Wang ◽  
...  

Abstract Disease relapse is a significant cause of treatment failure after allogeneic hematopoietic stem cell transplantation (HCT). In the setting of reduced-intensity conditioning (RIC), a graft-versus-leukemia (GVL) effect is critical for successful outcomes in patients with advanced myeloid malignancies. A GVL effect has been attributed in part to donor-derived alloreactive natural killer (NK) cells, which are regulated by interaction of KIRs with their HLA-class I ligands. Several models of NK reactivity (missing KIR ligand, centromeric haplotype-B content, non-tolerized KIR2DS1) have been associated with improved outcomes following HLA-matched, HLA-mismatched, related, and unrelated donor HCT, particularly for AML patients given myeloablative conditioning. The effect of KIR-HLA combinations on outcomes after RIC HCT, however, is not known. We retrospectively analyzed donor-recipient KIR/HLA genotypes from 929 URD HCTs facilitated by the National Marrow Donor Program for patients with AML (n=624) or MDS (n=305) treated with RIC between 1990 and 2007. 664 donor-recipient pairs were 10/10 HLA-matched and 265 were 9/10 HLA-matched. 332 (37%) patients received ATG and 73 (8%) received alemtuzumab. P-values less than 0.01 were considered significant. We hypothesized that donor-recipient KIR-HLA interactions may be associated with improved post-transplant outcomes following RIC HCT for AML and MDS. Patients lacking the HLA-Bw4 ligand for donor inhibitory KIR3DL1 experienced lower relapse following HCT at 1 year (27 vs 36%, p=0.002) and 5 years (31 vs 42%, p=0.003) compared to patients with the Bw4 ligand (Figure). The lower risk for relapse was confirmed in multivariate analysis (HR 0.71, p=0.005). However, there was no significant association of Bw4 ligand with disease-free survival (HR 0.84, p=0.05) and overall survival (HR=0.97, p=0.70). Risk for acute GVHD was higher among patients lacking KIR ligands after adjusting for other clinical factors. In particular, patients lacking HLA-C2 for donor KIR2DL1 experienced higher grade 2-4 (HR 1.3, p=0.005) and 3-4 acute GVHD (HR 1.5, p=0.002), and patients lacking multiple KIR ligands experienced higher grade 3-4 acute GVHD (HR 1.5, p=0.007). The analysis was then restricted to AML patients, the patient population with greatest reported KIR-HLA effects. Patients whose donors were KIR2DS1+ and HLA-C2C2 (n=33) had higher transplant-related mortality (TRM) (HR, 2.4, p=0.002) compared to all other patients. There was no significant effect of KIR2DS1 with HLA on relapse. In a multivariate analysis, lack of HLA-C2 in AML patients was associated with higher grade 2-4 (HR 1.4, p=0.002) and 3-4 acute GVHD (HR 1.5, p=0.01), and risk for grade 3-4 acute GVHD was higher in patients lacking multiple KIR ligands (HR 1.6, p=0.005). There were no significant associations between donor homozygosity for the centromeric B-haplotype (cenBB) or overall B-haplotype KIR content and RIC HCT outcomes. Overall, these results suggest that in the RIC HCT setting, lack of Bw4 ligand for KIR3DL1 is associated with a lower risk of relapse for AML/MDS. This observation corroborates previous findings in myeloablative HCT transplants. Furthermore, tolerance of donor KIR2DS1 by HLA-C2C2 was associated with worse outcome, as manifested by higher TRM, in AML patients. In contrast, it appears that in RIC HCT homozygosity for the centromeric B-haplotype does not have a significant role in leukemia relapse. The associations of KIR ligands with acute GVHD were not previously observed suggesting that NK cell alloreactivity depends on multiple variables, including RIC. Further elucidation of the biology of NK cell alloreactivity in the RIC setting may provide guidance for future approaches to help optimize conditions for generating GVL reactions without GVHD and less TRM in this transplant population.FigureFigure. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 541-541 ◽  
Author(s):  
Barbara Cappelli ◽  
Francoise Bernaudin ◽  
Annalisa Ruggeri ◽  
Myriam Labopin ◽  
Fernanda Volt ◽  
...  

Abstract Introduction: Hematopoietic stem cell transplantation (HSCT) is, to date, the only curative therapy for sickle cell disease (SCD). However, HSCT is offered to relatively few patients with SCD for a number of reasons including lack of a suitable HLA-matched donor, lack of consensus on indications for HSCT, the potential for trading one chronic condition (i.e., SCD) for another, such as chronic graft-versus-host disease (GVHD), and the mortality associated with the procedure. To-date, most HSCTs for SCD have utilized matched siblings as donors and are performed in children and adolescents. We report outcomes after HLA-matched sibling HSCT of patients reported to the Eurocord-Monacord/European Group for Blood and Marrow Transplantation (EBMT) and Center for International Blood and Marrow Transplant Research (CIBMTR). Material and methods: One thousandpatients with SCD received HLA identical sibling HSCT between 1991 and 2013; n=439 from CIBMTR and n=561 from EBMT centers. HSCTs were performed in 90 centers in 23 countries. Results: Median age at HSCT was 9 years (range 1-54y); 85% of patients were aged <16 years. Approximately half of patients were female and 53% of HSCTs were performed after 2007. Most patients (94%) were homozygotes for hemoglobin S (HBS). The most common indication for HSCT was stroke. Other indications included: central nervous system event lasting longer than 24 hours, elevated cerebral arterial velocity, acute chest syndrome or vaso-occlusive crisis requiring hospitalization. Red blood cell transfusions were given before HSCT to 93% and hydroxyurea to 56% of the evaluable patients (N=510). Most HSCTs (n=872; 87%) used myeloablative-conditioning regimens, mainly based on the combination of busulfan with cyclophosphamide (n=719; 82%) or fludarabine (n=82; 9%). One hundred and twenty six patients (13%) received reduced intensity conditioning regimens; fludarabine with cyclophosphamide was the predominant regimen (n=48; 38%). Most regimens included in vivo T-cell depletion (71%) with anti-thymocyte globulin (n=630) or alemtuzumab (n=76). The predominant GVHD prophylaxis regimens were cyclosporine alone (19%), or combined with methotrexate (56%). The predominant stem cell source was bone marrow (84%); peripheral blood and cord blood were employed in 7% and 9% of patients, respectively. The median follow-up was 45 (1.1-324.6) months. The cumulative incidence (CI) of neutrophil engraftment at day+60 was 98% (96.6% for CB, 98.3% for BM and 95.2% for PB) with a median time to recovery of 19 days, while that for platelet engraftment was 98 % (96±2% for CB, 99±1% for BM and 98±9% for PBSC) with a median time to recovery of 25 days. Twenty-six patients experienced primary and 47 patients secondary graft failure; 67 patients died mainly due to GVH or infection. The 3-year probabilities of overall (OS) and event-free survival (EFS, alive with engraftment) were 94% (95% CI 92-95) and 90% (95% CI 68-82), respectively. According to stem cell source, 3-year OS was 99% after CB, 94% after BM and 80% after PBS (p<0.0001). In multivariate analysis, every year in age increment (HR 1.1, 95% CI 1.07-1.14, p<0.001) and use of peripheral blood (HR 3.43, 95% CI 1.49-7.88, p=0.004) were associated with higher mortality. In univariate analysis, EFS was better in patients receiving myeloablative compared to reduced intensity conditioning (91±1% vs 82 ±1%, respectively; p<0.001). In multivariate analysis, EFS was lower with every year in age increment (HR 1.05, 95% CI 1.02-1.07, p<0.001), peripheral blood grafts (HR 1.83, 95% CI 1.07-3.15, p=0.03) and HSCTs prior to 2000 (HR 0.77, 95% CI 0.64-0.92, p=0.005). CI of acute GVHD grade 2-4 was 14.4% (12.2-16.7) of chronic GVH 13.3 (11-15.8). Risks of acute GVHD were higher with increasing age (HR1.04 95% CI 1.01-1.07, p=0.008). None of the variables tested were associated with chronic GVHD. Conclusion: This large registry based international study shows that HLA identical sibling transplant is successful more than 90% of the patients with severe SCD with limited transplant related complications (rejection, GVHD). Strategies aimed at lowering graft failure and GVHD are desirable to further optimize the observed 3-year event-free survival. Importantly, these data should increase awareness to early referral to HSCT of patients with severe SCD. Disclosures Walters: ViaCord and AllCells, Inc: Other: Medical director. Bertrand:ERYTECH Pharma: Consultancy. Peters:Medac: Research Funding; Fresenius: Research Funding; Amgen: Research Funding; Jazz: Research Funding; Novartis: Research Funding; Pfizer: Research Funding; Sanovi: Research Funding; Pierre-Fabre: Research Funding.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4489-4489
Author(s):  
Joshua A Fein ◽  
Avichai Shimoni ◽  
Ivetta Danylesko ◽  
Noga Shem-Tov ◽  
Ronit Yerushalmi ◽  
...  

Background: In recipients of allogeneic hematopoietic stem cell transplantation (HSCT), organ toxicity is a barrier to administering high-intensity conditioning regimens. We hypothesized that determinants of acute organ toxicity are specific to individual conditioning regimens. We sought to characterize toxicities across common transplantation regimens, evaluate their prognostic implication, and derive predictors of severe toxicity at the regimen level. Methods: This retrospective study included adults undergoing first allogeneic HSCT at a single center between the years of 2001 and 2014 (median: 2010). Patients received grafts from matched sibling or unrelated donors and were conditioned with any of the following regimens: Cyclophosphamide + TBI (Cy/TBI), Busulfan + Cyclophosphamide (Bu/Cy), Fludarabine + 12.8 mg Busulfan (Flu/Bu4), Fludarabine + 6.4 mg Busulfan (Flu/Bu2), Fludarabine + 36-42 gr/m2 Treosulfan (Flu/Treo), and Fludarabine + 100-140 mg/m2 Melphalan (Flu/Mel). Toxicities were defined by the KDIGO scale for acute kidney injury (AKI) and by the CTCAE v. 5.0 for increases in total bilirubin, AST, ALT, and alkaline phosphatase (Alk. Phos.) The incidence of toxicities from the start of conditioning through 30 days post-transplantation was tabulated by regimen. Risk factors for severe organ toxicity were assessed within each regimen cohort using multivariable logistic regressions. Results: In a cohort of 707 patients, the median age was 52 years. The main indications for transplantation were acute leukemia (57%), myelodysplastic syndrome (13%), and aggressive lymphoma (9%). Graft-versus-host-disease prophylaxis included methotrexate in 80% of patients, and 56% received anti-thymocyte globulin (ATG). The most common regimens were Flu/Treo (n = 160) and Bu/Cy (n = 141). As expected, patient characteristics varied between regimens. The incidence of AKI and increased serum bilirubin in each regimen is shown in Figure 1A and 1B, respectively. Sinusoidal-obstructive syndrome (6% overall) accounted for only 17% of gr. ≥ 3 bilirubinemia in the entire cohort. Elevations in AST, ALT, and Alk. Phos of gr. ≥ 3 were not common (<8%). In multivariable logistic regression, AKI gr. ≥ 2, increased bilirubin gr. ≥ 3, AST gr. ≥ 3, and Alk. Phos. gr. ≥ 2 were associated with increased 100-day mortality (p < 0.05). Acute severe organ toxicity (ASOT) was defined as the occurrence of any of these toxicities. ASOT had an odds ratio (OR) of 3.4 (95% CI: 2.2-5.3) for 100-day mortality. Within each regimen, we studied the relationship between ASOT and transplantation/patient characteristics (Figure 1C). Elevations in baseline bilirubin were predictive of ASOT in Cy/TBI (OR: 1.68 [1.19-2.37]), while increasing creatinine was predictive in patients conditioned with Flu/Mel (OR: 1.43 [1.09-1.88]). High-risk disease (DRI) was associated with increased risk in patients receiving Flu/Bu4 (1.26 [1.01-1.58]). In patients treated with Bu/Cy, administration of ATG increased the risk of ASOT (1.31 [1.11-1.55]). Conclusion: Allogeneic stem cell transplantation recipients are at high risk for acute organ damage. We describe patterns of renal and liver toxicity across several regimens. Determinants of acute severe organ toxicity, defined as those associated with short-term mortality, are regimen dependent. Our findings suggest that these factors should be considered when selecting the preparative regimen. While requiring validation, the newly-defined composite endpoint of acute severe organ toxicity (ASOT) may be valuable in studying transplantation strategies. Figure 1 Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2314-2314 ◽  
Author(s):  
Reggie Duerst ◽  
David Jacobsohn ◽  
William T. Tse ◽  
Morris Kletzel

Abstract Reduced Intensity Conditioning (RIC) regimens prior to allogeneic HSCT have gained acceptance in the treatment of adults with myelodysplasia, leukemia and multiple myeloma. RIC reduces the risk for regimen related morbidity and mortality enabling patients with pre-existing medical conditions that would have been precluded from allogeneic HSCT to attempt a curative approach. The resilience of pediatric patients (pts) following high-dose conditioning regimens and the concern that ALL cells are inherently more resistant to a graft-vs-leukemia effect have limited accrual of pediatric ALL pts to RIC protocols despite the potential benefit for reduced long-term morbidity. We report the experience of 10 pediatric ALL pts (6 M, 4 F, median age 9.5 years) treated for recurrent ALL with RIC and allogeneic HSCT. A uniform RIC regimen comprised of fludarabine, 30 mg/m2 for 6 consecutive days (days −10 through −5), followed by intravenous busulfan, 0.8 – 1 mg/kg for 8 doses or targeted AUC 4000 μMol*min for 2 doses (days −5 and −4) and equine ATG, 40 mg/kg or rabbit ATG, 2 mg/kg for 4 days (days −4 through −1) was administered. Pts with prior CNS involvement received whole brain (2400 cGy) and spinal (1800 cGy) irradiation immediately prior to the RIC. Stem cell sources included 7 unrelated donors and 3 matched sibs. 9 of 10 stem cell donations were peripheral blood stem cells (PBSC). The median cell doses infused were 6.5 x 108 MNC/kg and 4.2 x 106 CD34+ cells/kg. Graft-versus-host disease (GVHD) prophylaxis was cyclosporin A (CsA) alone in 5 patients, CsA and mycophenolate mofetil in 5 pts. Growth factor support was not used. Each of the pts had at least two very high-risk features--prior HSCT (n = 6), CR > 3/refractory disease (8), prior CNS disease (6), Ph+ (2), pre-exisiting neurologic (1) or cardiac (1) dysfunction or aspergillous infection (1). Full donor chimerism was achieved in 9 of 10 with a median time to reach an ANC >500/μl of 16 days (range 11–62) and an unsupported platelet count > 20,000/μl was achieved in 8 of 10 at a median of 25 days (15–67). 2 pts developed Gr IV acute GVHD, 2 of 5 pts surviving more than 100 days developed chronic GVHD. Only 3 patients have relapsed: 1 refractory T-ALL pt recurred day +27 and 2 Ph+ pts had a molecular relapse day +61 and +196. The latter pt is in subsequent continuous molecular remission for over 1 year on imatinib therapy. 6 pts have died, 5 in the first 100 days of HSCT from complications of GVHD (2), relapse (1), pulmonary failure (in 1 pt S/p 3 prior allogeneic HSCT) and PTLD (1). 1 pt succumbed from complications of chronic GVHD day +756. The RIC regimen and supportive care are primarily an outpatient experience. During the first 30 days post HSCT, pts spent an average of only 9 days in hospital (23 of the first 100 days). Despite very high-risk features, 4 of 10 pts survive (3 CCR) at a median of 500 days post HSCT. Thus, RIC and allogeneic HSCT also offers promise for efficacy in pediatric ALL.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2948-2948
Author(s):  
Jerzy Holowiecki ◽  
Sebastian Giebel ◽  
Jerzy Wojnar ◽  
Miroslaw Markiewicz ◽  
Aleksandra Holowiecka-Goral ◽  
...  

Abstract Unrelated donor - hematopoietic stem cell transplantation (URD-HSCT) is the treatment of proved long-term efficacy for chronic myeloid leukemia (CML) patients not having an HLA-identical sibling. However, high procedure-related toxicity observed after oral busulfan- or TBI-based conditioning limits its applicability and deteriorates outcome [Radich, Blood2003, 102, 31–5]. This is of increasing importance in the presence of challanging options offered by tyrosine kinase inhibitors. Between 2003–2006 we introduced a new preparetive regimen consisting of Treosulfan (a soluble alkylyting agent) 14 g/m2/d on days -6, -5, -4, Fludarabine 30 mg/m2/d on days -6, -5, -4, -3, -2, and, anti-thymocyte globulin (ATG) at a total dose of 6 mg/kg. Thirty patients (age 32, range 16–48 years) with CML in the 1st chronic phase (n=29) or in 2nd chronic phase (n=1) were included in the study. Median interval from diagnosis to alloHSCT equaled 1.0 (0.5–12.0) years. 63% of patients had previously been treated with Imatinib. The donors were selected based on high resolution typing for both HLA class I and II. 43% of donors were mismatched for a single HLA-C (n=9), HLA-DQB1 (n=3) or HLA-B locus (n=1). Bone marrow was used a source of stem cells in 19 patients, peripheral blood - in 11 cases. GVHD prophylaxis consisted of Cyclosporin A and short-course Methotrexate. All patients engrafted with the median time to neutrophil recovery >0.5 G/L and PLT >50 G/L of 19 (10–30) days and 18 (12–29) days, respectively. Complete donor chimerism was achieved until day +100 in all but one patient. Grade 3–4 neutropenic infections occurred in 13% of patients. Grade 3–4 mucositis as well as hepatic toxicity including VOD were not observed. The incidence of grade II acute GVHD was 23%, whereas grade III-IV acute GVHD was not observed. The incidence of extensive chronic GVHD was 10%. At 3 years the probability of the overall survival and hematological relapse-free survival equaled 82% (+/−7%). The cumulative incidence of non-relapse moratlity was 18% (+/−7%) (fungal infection n=3, bacterial infection n=1, EBV-LPD n=1). Four patients required donor lymphocyte infusion or additional interferon or imatinib treatment because of incomplete donor chimerism or molecular/cytogenetic relapse after initial response. We conclude that treosulfan + fludarabine + ATG conditioning is associated with low organ toxicity, low incidence of severe GVHD and NRM. The regimen is feasible option for CML patients referred for URD-HSCT in tyrosine kinase inhibitors era.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5311-5311
Author(s):  
Xiaohua Chen ◽  
Gregory A. Hale ◽  
Raymond C. Barfield ◽  
Ely Benaim ◽  
Wing H. Leung ◽  
...  

Abstract Haploidentical hematopoietic stem cell transplantation (HaploHSCT) from a mismatched family member (MMFM) donor offers an alternative option for patients who lack an HLA-matched donor. The main obstacles to successful haploidentical hematopoietic stem cell transplantation from a mismatched family member donor are delayed immune reconstitution, vulnerability to infections, and severe graft-versus-host disease (GvHD). Method: We designed a reduced-intensity conditioning regimen that excluded total body irradiation and anti-thymocyte globulin. The graft was immunomagnetically depleted of CD3+ T-cells (CD3 negative selection) and contained a large number of both CD34+ and CD34− stem cells and most other immune cells especailly NK cells. This protocol was used to treat 22 pediatric patients with refractory hematologic malignancies. Results and Discussion: After transplantation, 91% of the patients achieved full donor chimerism. They also showed rapid recovery of CD3+ T-cells, T-cell receptor excision circle counts, TCRβ repertoire diversity and NK-cells during first four months post-transplantation. The incidence and extent of viremia were limited and no lethal infection was seen. Only 9% of patients had grade 3 acute GvHD, while 27% patients had grade 1 and another 27% had grade 2 acute GvHD. This well-tolerated regimen appears to accelerate immune recovery and shorten the duration of early post-transplant immunodeficiency, thereby reducing susceptibility to viral infections. Rapid T-cell reconstitution, retention of NK-cells in the graft, and induction of low grade GvHD may also enhance the potential anti-cancer immune effect.


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