Fludarabine-based Conditioning Research Articles

Outcomes from hematopoietic stem cell transplantation following treosulfan-based conditioning: A clinical and pharmacokinetic analysis.

The aims of this study are to report our experience with treosulfan-based conditioning regimens for patients with non-malignant hematologic conditions, correlating clinical outcomes at different time points post-transplant with treosulfan exposure (AUC). This study was a single-center observational study investigating overall survival (OS), disease-free survival (DFS), and event-free survival (EFS) end-points post-transplant. The consequences of treosulfan AUC with respect to toxicity, correction of underlying disease, and long-term chimerism were also explored using pharmacokinetic analysis. Forty-six patients received 49 transplants with treosulfan and fludarabine-based conditioning between 2005 and 2023. Twenty-four patients also received thiotepa. Donor chimerism was assessed on either whole blood or sorted cell lines at different time points post-transplant. Thirty-nine patients received treosulfan pharmacokinetic assessment to evaluate cumulative AUC, with five infants receiving real-time assessment to facilitate daily dose adjustment. OS, DFS, and EFS were 87%, 81%, and 69%, respectively. Median follow-up was 32.1 months (range 0.82-160 months) following transplant. Lower EFS was associated with patient age (<1 year; p = .057) and lower cumulative treosulfan dose (<42 g/m2; p = .003). Stable donor chimerism in B-cell, NK-cell, and granulocyte lineages at 1-year post-transplant were more prevalent in patients receiving thiotepa conditioning. Two infants required daily dose adjustment to treosulfan to avoid high AUC. Excellent clinical outcomes and stable chimerism were observed in this patient series. The addition of thiotepa conferred no significant toxicity and trended toward sustained ongoing donor engraftment. Correlating treosulfan AUC with long-term patient outcomes is required.

Impact of Different Fludarabine Doses in the Fludarabine-Based Conditioning Regimen for Unrelated Bone Marrow Transplantation

The purine analog fludarabine (Flu) plays a central role in reduced-intensity conditioning and myeloablative reduced-toxicity conditioning regimens because of limited nonhematologic toxicities. Few reports assess the impact of different dose of Flu on the clinical outcomes and the Flu doses vary across reports. To compare the effect of Flu dose, the clinical outcomes of patients who received Flu and busulfan (FB; n = 1647) or melphalan (Flu with melphalan (FM); n = 1162) conditioning for unrelated bone marrow transplantation were retrospectively analyzed using Japanese nationwide registry data. In the FB group, high-dose Flu (180 mg/m2; HFB) and low-dose Flu (150/125 mg/m2; LFB) were given to 1334 and 313 patients, respectively. The 3-year overall survival (OS) rates were significantly higher in the HFB group than in the LFB group (49.5% versus 39.2%, P < .001). In the HFB and LFB groups, the cumulative incidences were 30.4% and 36.6% (P = .058) for 3-year relapse and 25.1% and 28.1% (P = .24) for 3-year nonrelapse mortality (NRM), respectively. In the multivariate analysis for OS and relapse, Flu dose was identified as an independent prognostic factor (hazard ratio: 0.83, P = .03; hazard ratio: 0.80, P = .043). In the FM group, high-dose Flu (180 mg/m2; HFM) and low-dose Flu (150/125 mg/m2; LFM) were given to 118 and 1044 patients, respectively. The OS, relapse, and NRM after 3 years did not differ significantly between the HFM and LFM groups (48.3% versus 48.8%, P = .92; 23.7% versus 27.2%, P = .55; 31.9% versus 30.8%, P = .67). These findings suggest that high-dose Flu was associated with favorable outcomes in the FB group but not in the FM group.

Comparison of fludarabine-based conditioning regimens in adult cord blood transplantation for myeloid malignancy: A retrospective, registry-based study.

Fludarabine/busulfan and fludarabine/melphalan are viable options as conditioning regimens. However, the optimal fludarabine-based conditioning in cord blood transplantation (CBT) remains unclear. Therefore, this retrospective, registry-based study aimed to analyze the impact of five fludarabine-containing conditioning regimens on 1395 adult patients (median age, 61 years) with acute myeloid leukemia, myelodysplastic syndrome, and chronic myeloid leukemia who underwent their first CBT. Treatment outcomes of fludarabine combined with melphalan (100-140 mg/m2 ) and low-dose total body irradiation (TBI; FM140T); melphalan (80-99 mg/m2 ) and TBI (FM80T); busulfan (12.8 mg/kg) and melphalan (FB4M); busulfan (12.8 mg/kg) and TBI (FB4T); and busulfan (6.4 mg/kg) and TBI (FB2T) were compared. The 3-year survival rate was 67%, 53%, 44%, 36%, and 39%, respectively (p < .0001). The FM140T survival rate was the most favorable after adjusting for confounders, and the hazard ratios (vs. FM140T) for overall mortality were as follows: FM80T, 1.6 (95% confidence interval [CI], 1.2-2.2); FB4M, 2.1 (95% CI, 1.6-2.8); FB4T, 2.7 (95% CI, 2.0-3.7); and FB2T, 2.2 (95% CI, 1.6-3.1). The better survival observed with FM140T, regardless of the disease, disease risk, age, or transplant year, was attributed to the lower relapse rate and lower non-relapse mortality (NRM) associated with fewer infectious deaths. Conversely, FB4T was associated with a higher relapse rate and higher NRM. The findings indicate that the outcomes of CBT in myeloid malignancies were highly dependent on both the alkylating agent and its dose in combination with fludarabine. Therefore, compared with fludarabine/busulfan-based conditioning, FM140T may be the preferred regimen.

Bone Marrow Versus Peripheral Blood in HLA-Matched Sibling Transplantation: Does the Stem Cell Source Matter in Severe Aplastic Anemia?

Background Selecting a graft source is critical in HLA-matched sibling donor hematopoietic stem cell transplantation (MSD-HCT) for severe aplastic anemia (SAA). Since graft-versus-host-disease (GVHD) is the major cause of mortality after MSD-HCT, and SAA patients do not need the graft-versus-leukemia effect, the selection of a suitable source of stem cells becomes critical. Although bone marrow (BM) is the preferable stem cell source based on the registry-based studies, mobilized peripheral blood stem cells (PBSC) may offer faster engraftment with rapid immune reconstitution. Moreover, the recent advances in conditioning regimens have significantly reduced transplantation-related complications. Here, we compared the long-term outcomes of BM vs PBSC as a graft source in adult patients with SAA who received MSD-HCT with the reduced intensity conditioning (RIC) regimen. Method We conducted a retrospective analysis of 171 consecutive SAA adult patients who received MSD-HCT with Flu6/Cy2/ATG4 RIC regimen (Flu, 30 mg/m 2 IV for 6 days: Cy, 50 mg/kg IV for 2 days; rabbit ATG, 2.5 mg/kg IV for 4 days) or total nodal irradiation (TNI) of 750 cGy combined with ATG as GVHD prophylaxis (TNI-750/ATG) from March 2002 to March 2021 at Seoul St. Mary's Hospital, Seoul, Korea. BM was the primary graft source, but PBSC was used in donors who refused BM harvest, were unsuitable for general anesthesia, or received TNI-750/ATG conditioning. The primary endpoint of this study was to compare the overall survival (OS), and the secondary endpoints included speed of hematologic recovery, primary or secondary graft failure (GF), and failure-free survival (FFS) between the BM and PBSC group. Results The median patient age in the BM group was 38 years (range, 15 - 59) and 44 years (range, 19 - 64) in the PBSC group (p=0.005). There were no differences of baseline characteristics between the two groups except for a donor-to-recipient sex discrepancy (female to male, BM vs. PBSC; 16.4% vs. 30.9%, p=0.029). The majority of BM group (114/116, 98.2%) received the Flu6/Cy2/ATG4 RIC regimen, while 38.2% (21/55) of PBSC group received TNI-750/ATG for the conditioning (p&amp;lt;0.001). The PBSC contained a median 4.71 (range, 1.22 - 17.03) x 10 6/kg CD34 + cells and 368.82 (range, 25.12 - 1234.70) x 10 6/kg CD3 + cells which were about 1.7-fold (BM 2.80 x 10 6/kg CD34 + cells; range, 0.25 - 10.05) and 10-fold (BM 39.61 x 10 6/kg CD3 + cells; range, 1.34 - 463.68) higher than the BM graft (p&amp;lt;0.001). Consequently, the PBSC group exhibited faster engraftment of neutrophils (median 13 vs. 11 days, p&amp;lt;0.001) and platelets (median 18 vs. 12 days, p=0.012). However, there were no differences in the incidence of secondary GF (19.0% vs. 12.7%, p=0.386) and donor-type aplasia (4.3% vs. 10.9%, p=0.178) between two groups. Furthermore, the incidence of acute grade I-II (8.6% vs. 10.9%, p=0.619) and moderate to severe chronic graft-versus-host disease (GVHD) (3.5% vs. 5.5%, p=0.542) were also not significantly different between two groups. However, the BM group has shown more CMV reactivation (44.0% vs. 24.9%, p=0.005), and higher incidence of respiratory infection (14.7% vs. 3.6%, p=0.037) than those of the PBSC group. The incidences of transplantation-related complications between the BM and PBSC group are summarized in Table. The 10-year OS (93.8% vs. 98.1%, p=0.246) and FFS (65.7% vs. 69.0%, p=0.455) were comparable (Figure). Moreover, there was no significant difference in FFS between BM and PBSC group by potential risk factors of patient and donor age at MSD-HCT, sex incompatibility, ABC mismatch, PNH clone presence, HCT-CI ≥3, infused CD34 + cell count, interval from diagnosis to transplant, prior IST history, heavy transfusion before allo-HCT, or severity of AA. Conclusions Our results suggest that survival outcomes of MSD-HCT showed no difference between BM and PBSC as graft sources, and using PBSC may be an efficient alternative offering faster engraftment without significant difference in graft failure or transplantation-related adverse events such as GVHD, and survival. Current analysis and results were drawn from the Asian population with a fludarabine-based conditioning regimen and therefore, need to validate in the Western population. In addition, well-designed prospective studies in a larger cohort are required to confirm our findings.

WT1-mutated acute myeloid leukemia is sensitive to fludarabine-based chemotherapy and conditioning regimens

We conducted a retrospective analysis of WT1-mutated acute myeloid leukemia (AML) patients who underwent allogeneic stem cell transplant. Thirty-seven patients with WT1-mutated AML were identified. Primary induction failure (40%) and early relapse rate (18%) after idarubicin/cytarabine (7 + 3) chemotherapy were observed. All patients with induction failure subsequently achieved CR with additional chemotherapy. There was no significant difference between outcomes after myeloablative vs. reduced intensity (Fludarabine/Melphalan [Flu/Mel]) conditioning regimens. RFS but not OS was significantly better in patients who received FLAG-IDA prior to transplant and/or a fludarabine-containing conditioning. In an independent ex vivo study, WT1-mutated AML samples exhibited greater sensitivity to fludarabine (p = 0.026) and melphalan (p = 0.0005) than non-WT1-mutated AML samples while there was no difference between sensitivity to cytarabine. Our data favor using a fludarabine-based induction for AML with WT1 mutation instead of 7 + 3. Fludarabine conditioning regimens for alloHCT showed better RFS but not OS.

FLUDARABINE-BASED LOW-INTENSITY CONDITIONING FOR FANCONI ANEMIA IS ASSOCIATED WITH GOOD OUTCOMES IN APLASTIC ANEMIA BUT NOT IN MDS - A SINGLE-CENTER EXPERIENCE

Background: Hematopoietic stem cell transplantation [HSCT] is the only curative option for Fanconi Anemia (FA) patients with hematological abnormalities.&#x0D; Materials and Methods: This is a retrospective analysis of patients with FA who underwent a matched-related donor HSCT.&#x0D; Results: Sixty patients underwent 65 transplants between 1999-2021 using a fludarabine-based low-intensity conditioning regimen. The median age at transplant was 11 years (range: 3-37). Aplastic anemia (AA) was the underlying diagnosis in 55 (84.6%) while 8 (12.4%) had myelodysplastic syndrome (MDS) and 2 (3%) had acute myeloid leukemia (AML). The conditioning regimen used was fludarabine with low-dose cyclophosphamide for aplastic anemia and Fludarabine with low-dose busulfan for MDS/AML. Graft versus host disease (GVHD)prophylaxis consisted of cyclosporine and methotrexate. Peripheral blood stem cells was the predominant graft source (86.2%). Engraftment occurred in all but 1 patient. The median time to neutrophil and platelet engraftment was 13 days (range: 9-29) &amp; 13 days (range: 5-31), respectively. Day 28 chimerism analysis showed complete chimerism in 75.4 % and mixed chimerism in 18.5%. Secondary graft failure was encountered in 7.7%. Grade II–IV acute GVHD occurred in 29.2% while Grade III-IV acute GVHD occurred in 9.2%. Chronic GVHD was seen in 58.5% and was limited in most patients. The median follow-up is 55 months [range: 2-144] &amp; the 5-year estimated overall survival (OS) is 80.2 ± 5.1%. Secondary malignancies were noted in 4 patients. The 5-year OS was significantly higher in patients undergoing HSCT for AA (86.6 + 4.7%) as compared to MDS/AML (45.7+16.6%) (p= 0.001).&#x0D; Conclusion: SCT using a fully matched donor provides good outcomes with low-intensity conditioning regimens in patients with FA who have an aplastic marrow.

Successful treatment of DOCK8 deficiency by allogeneic hematopoietic cell transplantation from alternative donors.

Dedicator of cytokinesis 8 (DOCK8) deficiency is a rare autosomal recessive inborn error of immunity (IEI) characterized by eczematous dermatitis, elevated serum IgE, and recurrent infections, comprising a seemingly hyper-IgE syndrome (HIES). DOCK8 deficiency is only curable with allogeneic hematopoietic cell transplantation (HCT), but the outcome of HCT from alternative donors is not fully understood. Here, we describe the cases of two Japanese patients with DOCK8 deficiency who were successfully treated by allogeneic HCT from alternative donors. Patient 1 underwent cord blood transplantation at the age of 16years, and Patient 2 underwent haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide at the age of 22years. Each patient received a fludarabine-based conditioning regimen. Their clinical manifestations, including refractory molluscum contagiosum, promptly improved post-HCT. They achieved successful engraftment and immune reconstitution without serious complications. Alternative donor sources such as cord blood and haploidentical donors can be options for allogeneic HCT for DOCK8 deficiency.

Untreated Donor-Specific HLA Antibodies Are Associated With Graft Failure and Poor Survival After Haploidentical Transplantation With Post-Transplantation Cyclophosphamide in Pediatric Patients With Nonmalignant Disorders

Donor-specific HLA antibodies (DSAs) have been recognized as a major risk factor for graft failure (GF) in adult patients with malignancies undergoing haploidentical transplantation with post-transplantation cyclophosphamide (haplo-PTCy). However, the impact of DSAs after pediatric haplo-PTCy for nonmalignant disorders (NMDs) has been poorly reported. We sought to investigate whether preexisting DSAs adversely affect pediatric haplo-PTCy outcomes. We retrospectively analyzed 59 pediatric patients (≤21 years) who received their first haplo-PTCy for NMDs from January 2008 to December 2017. DSA testing was performed using single antigen beads, and mean fluorescence intensity (MFI) >1000 was considered positive, and MFI <1000 and >500 was considered potentially positive, based on HLA epitope reactivity patterns. Primary endpoints were neutrophil and platelet recovery and GF, whereas secondary endpoints included event-free and overall survival. Multivariable analyses were performed using Fine-Gray competing risk regression or Cox proportional hazards regression models. The median age was 10 years, and 66.1% were male. Main indications for haplo-PTCy were Fanconi anemia (n=33) and severe aplastic anemia (n=11). All patients received bone marrow as the graft source, and most patients (91.5%) received fludarabine-based conditioning. Overall, 15 patients (25.4%) had DSAs >500 MFI. Four patients had false-positive DSAs with median MFI of 1762. Of the 11 patients with true-positive DSA reactivity, 5 had 1 DSA, 5 had 2 DSAs, and 1 had 3 DSAs, with median MFI of 2372 (range 527-24,200). Four patients received desensitization therapy with rituximab and plasmapheresis, whereas 7 patients were untreated. All patients with treated DSAs achieved donor engraftment. In the multivariable analyses, untreated DSAs were associated with lower neutrophil recovery (subdistribution hazard ratio [SHR] = 0.15; 95% confidence interval [CI], 0.03-0.63; P=.001), increased GF (SHR=20.57; 95% CI, 6.57-64.43; P < .001), inferior event-free survival (hazard ratio [HR] = 10.09; 95% CI, 3.37-30.22; P < .001), and poor overall survival (HR 5.56; 95% CI, 1.92-16.12; P=.002). Both treated DSAs (SHR=0.26; 95% CI, 0.10-0.68; P=.006) and untreated DSAs (SHR=0.13; 95% CI, 0.04-0.37; P < .001) adversely affected platelet recovery. Our results indicate that the presence of DSAs is an independent predictor of poor outcomes after pediatric haplo-PTCy for NMDs. Therefore DSA-positive donors should be avoided whenever possible, and when a DSA-negative donor is unavailable, desensitization therapy must be performed to enhance the likelihood of donor engraftment and improve transplantation outcomes.

Favorable outcomes with durable chimerism after hematopoietic cell transplantation using busulfan and fludarabine-based reduced-intensity conditioning for pediatric patients with hemophagocytic lymphohistiocytosis

BackgroundThe incorporation of a reduced-intensity conditioning (RIC) regimen in hematopoietic cell transplantation (HCT) for patients with hemophagocytic lymphohistiocytosis (HLH) has decreased early mortality but is associated with a high rate of mixed chimerism and graft failure. Here, we present a successful single-center experience using busulfan and a fludarabine-based RIC regimen for the treatment of HLH.MethodsThe medical records of pediatric patients with HLH who underwent HCT using a busulfan/fludarabine-based RIC regimen between January 2008 and December 2017 were reviewed retrospectively.ResultsNine patients received HCT with a busulfan/fludarabine-based RIC regimen. Three patients had primary HLH, and the other six patients had secondary HLH with multiple reactivations. All three patients with primary HLH had UNC13D mutations. All patients achieved neutrophil and platelet engraftment at a median of 11 days (range, 10‒21) and 19 days (range, 13‒32), and all eight evaluable patients had sustained complete donor chimerism at the last follow-up. Two patients (22%) experienced grade 2 acute graft-versus-host disease (GVHD). Two patients (22%) developed chronic GVHD, and one died from chronic GVHD. One patient (11%) experienced reactivation 4 months after HCT from a syngeneic donor and died of the disease. The 8-year overall survival and event-free survival rates were 78%. No early treatment-related mortality within 100 days after HCT was observed.ConclusionOur experience suggests that a busulfan/fludarabine-based RIC regimen is a viable option for pediatric patients with HLH who require HCT.

Busulfan-fludarabine- or treosulfan-fludarabine-based myeloablative conditioning for children with thalassemia major.

Significant advances in supportive care for patients with transfusion-dependent thalassemia major (TDT) have improved patients' life expectancy. However, transfusion-associated iron overload remains a significant barrier to long-term survival with good quality of life. Today, allogeneic hematopoietic stem cell transplantation (HSCT) is the current curative standard of care. Alongside selection of the best available donor, an optimized conditioning regimen is crucial to maximize outcomes for patients with TDT undergoing HSCT. The aim of this retrospective analysis was to investigate the role of busulfan-fludarabine-based and treosulfan-fludarabine-based conditioning in TDT patients undergoing HSCT. We included 772 patients registered in the European Society for Blood and Marrow Transplantation (EBMT) database who underwent first HSCT between 2010 and 2018. Four hundred ten patients received busulfan-fludarabine-based conditioning (median age 8.6years) and 362 patients received treosulfan-fludarabine-based conditioning (median age 5.7years). Patient outcomes were retrospectively compared by conditioning regimen. Two-year overall survival was 92.7% (95% confidence interval: 89.3-95.1%) after busulfan-fludarabine-based conditioning and 94.7% (95% confidence interval: 91.7-96.6%) after treosulfan-fludarabine-based conditioning. There was a very low incidence of second HSCT overall. The main causes of death were infections, graft-versus-host disease, and rejection. In conclusion, use of busulfan or treosulfan as the backbone of myeloablative conditioning for patients with TDT undergoing HSCT resulted in comparably high cure rates. Long-term follow-up studies are warranted to address the important issues of organ toxicities and gonadal function.

Experience of Low Dose (25mg/Kg) of Cyclophosphamide (Chennai-Chezhian-Kishore PTCy Protocol) As Post Transplant Cyclophosphamide (PTCy) Dose in Haploidentical Bone Marrow Transplant

Introduction:-Haploidentical Bone marrow transplantation has become one of the most commonly employed alternative donor techniques, with many centers applying T-cell-replete strategies developed by the Baltimore group using high-dose post-transplant cyclophosphamide. The usefulness of this technique is to reduce graft acquisition cost, lesser grade of GVHD, and reduction in non-relapse mortality. One problem we face in a country like India is the worry of engraftment delay leading to refractory multi-drug resistant gram-negative sepsis increasing the risk of transplant-related mortality. We took up this pilot study to check for the feasibility of a low dose (50%) 25mg/kg of cyclophosphamide as PTCy and its impact on transplant outcomes especially GVHD.Methodology:-This study was done from January 2016 to June 2019. 41 Haploidentical bone marrow transplants were done for Acute Myeloid leukemia at this time under this protocol. 23 Cases had Busulfan / Fludarabine as conditioning and in 18 cases; we used Treosulfan / Fludarabine-based conditioning regimen. The study protocol PTCy dose was 25mg/kg on Day +3 and Day +4. Cyclosporine / Tacrolimus was used from day -1 in all patients as GVHD prophylaxis. The parameters analyzed are engraftment dynamics, rates of gram-negative sepsis, hemorrhagic cystitis, rates of acute and chronic GVHD, and 2-year Non-relapse mortality.Results:Parents were the haploidentical donors in 22 cases whereas siblings in the rest 19 cases. Peripheral blood stem cell collection was chosen in all cases. The average CD34 dose was 6.8 x 10 6/Kg of the recipient. The mean number of days to achieve engraftment was around day 11. Culture-proven gram-negative sepsis was seen in 11 cases (26.8%). Two patients died within Day +30. Both due to sepsis. The rates of acute GVHD of grade I/2 was 18 (43.9%) and grade 3/4 acute GVHD was seen only in 2 patients (5%). No mortality was due to GVHD. With a median follow-up of two years, chronic skin and liver grade 1/2 GVHD was noted in 29 patients (74.3%) but were manageable with oral and topical medications not needing admission. Three patients had hemorrhagic cystitis. CMV reactivation needing medications was seen in 5(12.2%) patients indicating a higher incidence of post-transplant viral reactivation with PTCy. At data cut-off, we had lost 12 patients due to relapse and there was no non-relapse mortality except for the two sepsis-related death.Conclusion:The results of this pilot study indicate the feasibility of using a low dose PTCy (25mg/kg) in Haploidentical transplant as a methodology for in vivo T cell depletion without increased incidence of GVHD and Non-relapse mortality in Indian patients. This is a small study and it needs further follow-up with drug metabolism analysis and a bigger cohort to make this Chennai-Chezhian-Kishore PTCy Protocol a validated standard in Haplo-identical transplants. This is a pilot study and we are planning to incorporate genetic polymorphism in drug metabolism to validate the proposed protocol more scientifically.Reference:1. Wang, Y et al. Low-dose post-transplant cyclophosphamide and anti-thymocyte globulin as an effective strategy for GVHD prevention in haploidentical patients. J Hematol Oncol 12, 88 (2019). https://doi.org/10.1186/s13045-019-0781-y2. Shannon R. McCurdy, Leo Luznik How we perform haploidentical stem cell transplantation with posttransplant cyclophosphamide Blood (2019) 134 (21): 1802-1810. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Hemoglobinuria in the Early Poststem-Cell-Transplant Period: Risk Factors and Association with Outcomes.

Information on risk factors of hemoglobinuria after hematopoietic stem-cell transplant (HSCT) and its association with AKI, mortality, and engraftment is limited. We conducted a retrospective cohort study on all consecutive adults that underwent HSCT from January 6, 1999, to November 6, 2017. The study included 6039 patients that underwent bone marrow transplantation (BMT), umbilical cord blood, and peripheral blood stem-cell transplantation (PBSCT). Early post-HSCT, AKI occurred in 393 (7%) patients, and 52 (0.9%) patients had post-HSCT hemoglobinuria. Post-HSCT hemoglobinuria was associated with graft type (BMT+Cord), underlying disease (lymphoma, acute leukemia), and fludarabine-based conditioning regimen. Post-HSCT hemoglobinuria was associated with early (48-72 hours) post-HSCT AKI. Graft type (BMT+Cord) was associated with AKI among patients with hemoglobinuria. AKI in patients with hemoglobinuria was associated with delayed platelet engraftment and delayed WBC engraftment but not 100-day mortality. Close monitoring is recommended in this patient group to facilitate a good engraftment outcome.

Excellent Outcome of Alternative Donor HSCT in Fanconi Anemia Using Chemotherapy Only Regimen: Single Korean Institution Experience

Title) Excellent outcome of alternative donor HSCT in Fanconi anemia using chemotherapy only conditioning regimen: single Korean institution experience.Introduction) Fanconi anemia (FA) is a rare autosomal (or X linked) recessive disorder characterized by bone marrow failure, secondary malignancies, and skeletal anomalies. Hematopoietic stem cell transplantation (HSCT) remains the standard treatment of hematologic disease. Although HSCT from a matched sibling donor (MSD) is the optimal mode of transplant, many patients lack such a donor necessitating alternative donor HSCT (AD-HSCT). Radiation treatment during the conditioning regimen results in a high incidence of post-HSCT complications in FA patients, while serotherapy with alemtuzumab has been reported to increase infectious toxicities. Here, we report on the excellent outcome of 15 FA patients who received AD-HSCT with a fludarabine-based conditioning regimen with in vivo T cell depletion using rabbit anti-thymocyte globulin (ATG).Methods and Results) We reviewed the medical records of FA patients diagnosed by chromosomal breakage test and who received AD-HSCT between September 2007 and December 2016. Median age at transplant was 10.8 years (4.2~18.6) and 7 were male (46.7%). Eleven of 14 patients who received genetic study for FA were found to have mutations (6 with FANC-A mutations (40%), and 5 with FANC-G mutations (33.3%)). Hematologic reasons for HSCT were severe aplastic anemia in 13 (93.3%) and myelodysplastic syndrome in 2 patients (13.3%). One patient received HSCT from a mismatched related donor, while the remaining patients received unrelated HSCT. Seven transplants were human leukocyte antigen (HLA) fully matched (13.3%). Cell sources were as follows: peripheral blood stem cells 9 (60%), cord blood 4 (26.7%), bone marrow 2 (13.3%). Conditioning regimen consisted of fludarabine 30mg/BSA/day x5days (D-8,-7,-6,-5,-4), cyclophosphamide 5mg/kg/day x4days (D-5,-4,-3,-2), rabbit ATG 2.5mg/kg/day x3days (D-3,-2,-1). Graft-versus-host disease prophylaxis consisted of cyclosporine and mini-dose methotrexate. Medians of infused cell doses were as follows: TNC 16.51 x108/kg (5.17~42.4), CD34+ 15.49x106/kg(3.49~33.7).Twelve patients (80%) showed initial engraftment and full donor chimerism according to short tandem repeat polymerase chain reaction (STR-PCR) analysis. Of the 3 patients who showed primary graft failure, one showed autologous recovery, while the remaining 2 received additional HSCs from the same donor and a haploidentical family donor respectively, leading to engraftment. Acute GVHD grade II or above was diagnosed in 8 patients (53.5%) and resolved with steroid therapy. Chronic GVHD developed in two patients, one mild and one of moderate severity. The patient with moderate oral chronic GVHD was diagnosed with squamous cell carcinoma of the tongue 5years after HSCT. She received surgical resection and remains disease-free for 40 months. After transplantation, 5 patients (33.3%) experienced infectious complications including viral reactivation, bacteremia and fungemia but all recovered without complications. At a median follow-up of 59.6 months (6.3~107.9) all 15 FA patients are alive and remain free of hematologic disease.Conclusion) FA patients who received AD-HSCT with fludarabine-based conditioning with in vivo T cell depletion using rabbit ATG showed excellent outcome with a lower rate of infectious toxicities than has been reported with conditioning incorporating alemtuzumab. The incidence of primary graft failure should be monitored in a larger cohort of patients. DisclosuresNo relevant conflicts of interest to declare.

Reduced-intensity conditioning-based hematopoietic cell transplantation for dyskeratosis congenita: Single-center experience and literature review.

Bone marrow failure in dyskeratosis congenita (DKC) is progressive, and allogeneic hematopoietic cell transplantation (HCT) is the only curative treatment. However, outcomes after HCT are suboptimal because of mucosal, vascular, pulmonary, and hepatic fragility, which can be exacerbated by chemotherapy conditioning and graft-versus-host disease (GVHD). These toxicities can be mitigated by reducing the intensity of the conditioning regimen. We performed a retrospective analysis on pediatric patients with DKC who underwent HCT at our institution between 2008 and 2019. We identified nine patients (median age, 5.7years) who underwent HCT with a fludarabine-based reduced-intensity conditioning (RIC) regimen. GVHD prophylaxis consisted of tacrolimus plus mycophenolate mofetil (MMF) (n = 8), tacrolimus/pentostatin (n = 1), or cyclosporine/MMF (n = 1). The median time to neutrophil engraftment was 19 days (range, 13-26 days), and the median time to platelet engraftment was 18 days (range, 17-43 days). Lung function, as measured by spirometry in six patients, remained stable during post-HCT observation. Six patients (67%) remain alive, with a median follow-up of 73.5 months. Because of toxicity after myeloablative conditioning, RIC is becoming standard for HCT in DKC. These results suggest that RIC regimen is feasible and safe for patients with DKC and does not accelerate pulmonary damage in the short-to-medium term after HCT.

Survival and toxicity outcomes of hematopoietic stem cell transplantation for pediatric patients with Fanconi anemia: a unified multicentric national study from the Spanish Working Group for Bone Marrow Transplantation in Children.

Hematopoietic stem cell transplantation (HSCT) is currently the only curative option for hematological manifestations in patients with Fanconi anemia (FA). We report the outcome of 34 patients with FA inside a collaborative multicenter national study based on recommendations of Spanish Working Group for Bone Marrow Transplantation in Children (GETMON) between 2009 and 2016. Fludarabine-based conditioning regimen was carried out in all patients, with low dose total body irradiation in unrelated transplants. Disease status before HSCT was bone marrow failure (BMF) in 30 patients and myelodysplastic syndrome (MDS) in four. Donors were matched siblings donors (MSD) in 18, matched unrelated donors (MUD) in 15, and one haploidentical donor. All except one patient engrafted. Cumulative incidence of grades II-IV acute graft-versus-host disease (GVHD) was 29% and 11% for chronic GVHD. Median follow-up after HSCT was 6.5 years. Seven patients (21%) died due to transplant-related causes, two (6%) because of MDS relapse, and one (3%) after a squamous cell carcinoma. Overall survival (OS) was 73% at 5 years post-transplant, with no differences between MSD and MUD transplants. OS for patients with BMF was 80% while for MDS was 25%. Our data suggest HSCT can cure hematologic manifestations of most FA patients with BMF.

Hematopoietic Cell Transplantation for Congenital Dyserythropoietic Anemia: A Report from the Pediatric Transplant and Cellular Therapy Consortium (PTCTC)

Introduction Congenital dyserythropoietic anemias (CDA) are a rare group of hereditary disorders characterized by anemia, ineffective erythropoiesis, and secondary hemochromatosis. While some CDA patients respond to interferon α therapy (type I CDA) or splenectomy (type II CDA), others are dependent on chronic red cell transfusions lifelong. Hematopoietic cell transplant (HCT), remains the only curative option for this disease. In 39 patients reviewed by the European Society for Blood and Marrow Transplant (EBMT), graft rejection (GR) was 12% (1-23%), the 3-year overall survival (OS) and event free survival (EFS) were 71% (55-87%) and 45% (45-63%) respectively1. A trend towards higher incidence of GR and severe (Grade III-IV) acute graft versus host disease (GvHD) was observed in patients with iron overload and unrelated donor HCT but these risk factors were not statistically significant1. We report the outcomes in 17 children with CDA who underwent HCT at participating Pediatric Transplantation and Cellular Therapy Consortium (PTCTC) centers. Methods Clinical information on transplant and associated outcomes were collected retrospectively after IRB approval using a common questionnaire. Data were analyzed using descriptive statistics. Comparisons between groups were made using Fisher's exact tests. Survival estimates and corresponding 95% confidence intervals were performed using the Kaplan-Meier method. Results Seventeen patients (11 males) with CDA were eligible by diagnosis and underwent HCT from 2002-2019. The median age at diagnosis was 0.7 (range: 0.2 - 14) years. A majority (n=12) of patients had CDA type II while the remainder either had CDA type I (n=2) or were unknown (n=3). Twelve (71%) patients had evidence of iron overload by biopsy or imaging and 11 received pre-HCT chelation. Three of the 12 patients had liver fibrosis confirmed by biopsy. Thirteen patients had splenomegaly and four underwent splenectomy prior to HCT. Three patients received pre-HCT immunosuppressive therapy (PTIS). Median age at the time of HCT was 5.5 (range: 0.7 - 15) years. The median interval between diagnosis and HCT was 3.8 (range 0 - 12.3) years. Most patients received myeloablative busulfan-based conditioning (n=12); however, 5 patients received nonmyeloablative (n=1) or reduced intensity (n=4) fludarabine-based conditioning regimens. Donor sources included HLA matched sibling (n=3), matched unrelated (n=9), haploidentical (n=1) and mismatched unrelated (n=4) donors. Graft source was bone marrow in all but 2 patients who received umbilical cord blood. The median total nucleated cell (TNC) dose for bone marrow grafts was 6.0 (range: 3.4- 20.6) x 108/kg. Cord blood recipients received a TNC dose of 3.8 x 107 and 4.8 x 107/kg. Five (29%) patients developed acute GvHD grade II-IV, with one patient with grade III-IV acute GvHD (5.8%). Post-HCT complications included veno-occlusive disease (n=3), acute kidney injury (n=1), congestive cardiac failure (n=1), thrombotic microangiopathy (n=1), CMV viremia requiring therapy (n=2), mucormycosis (n=1), streptococcal pneumonia (n=1), recurrent clostridium difficle colitis (n=1), and parvovirus infection (n=1). Four patients developed chronic GvHD (23.5%; 2 limited and 2 extensive). Characteristics and outcomes of the four patients (23.5%) who developed GR are shown in Table 1. With a median follow-up of 3.4 (range: 0.08 - 14) years; fourteen patients are alive. Three patients died from respiratory failure due to adenovirus, congestive cardiac failure and extensive chronic GvHD post 2nd HCT. The 2-year OS, EFS and GvHD-free-rejection-free survival of the entire cohort (95% confidence interval) were 87% (72-100%), 64% (44 -92%), and 58% (39- 88%), respectively (Figure 1). Due to limited sample size, we did not find any patient or HCT-related factors that were associated with GR, OS or GvHD. Conclusion HCT can be curative for patients with CDA. The incidence of GR and GvHD in our CDA cohort was comparable to the recent EBMT report1. Strategies such as aggressive chelation, use of PTIS and perhaps early HCT in the presence of a suitable donor before co-morbidities occur are needed to improve engraftment without increasing risk for toxicities and mortality. Not unexpectedly we observed considerable morbidities in patients who had GR and required a 2nd HCT. Disclosures Pulsipher: Novartis: Honoraria; Bellicum: Honoraria; Jasper: Honoraria; Mesoblast: Honoraria; Miltenyi: Honoraria, Research Funding; Adaptive: Research Funding.

Allogeneic Hematopoietic Stem Cell Transplant Offer Good Outcomes in Pediatric Aplastic Anemia: Experience From Developing World.

Between 2014 and 2020, 31 patients with severe aplastic anemia (SAA) underwent full match allogeneic hematopoietic stem cell transplantation at our center. Of the 31 patients with SAA, 19 had acquired aplastic anemia, 2 had Diamond Blackfan anemia and 10 had Fanconi anemia. Donors were either matched sibling (n=29), related donors (n=2), or unrelated donors (n=3). Peripheral blood stem cells were the graft source in all the cases except 1. Fludarabine-based reduced intensity conditioning was used in all except for patients with a diagnosis of Diamond Blackfan anemia. All patients except 1 achieved hematologic recovery in the form of neutrophil engraftment at 13 days (range, 9 to 17), whereas platelet engraftment occurred at 14 days (range, 10 to 18). Graft versus host disease (GvHD) prophylaxis consisted of cyclosporine and methotrexate ±antithymocyte globulin (horse/rabbit). Acute GvHD developed in 12.9% patients, whereas no patients developed chronic GvHD till the time of last follow-up. The 2-year overall survival for the entire cohort was 93.21±4.6%. In patients with SAA, allogeneic stem cell transplant using fludarabine-based conditioning regimens are very well tolerated and have excellent outcomes in a full match setting.

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.

Is immunological recovery clinically relevant at 100 days after allogeneic transplantation?

Background/AimsImmune reconstitution following allogeneic hematopoietic stem cell transplantation (HSCT) is affected by multiple variables during the transplantation.MethodsWe assessed the clinical factors contributing to immune function reconstitution at 100 days post-allogeneic HSCT in 114 patients receiving fludarabine-based conditioning. Immunophenotypic analysis using flow cytometry was performed to evaluate the percentage and the absolute numbers of T-cell subsets, natural killer cells, and B-cells as clinical outcomes.ResultsTacrolimus-based graft-versus-host disease (GVHD) prophylaxis, T-cell depletion, and acute GVHD were significantly associated with delayed immune reconstitution of T-cell subsets. The incidence of chronic GVHD was significantly increased in the normal recovery group compared to the abnormal group (p = 0.01). Epstein-Barr virus reactivation was more frequently observed in the abnormal group of T-cell subsets (p = 0.045). All viral reactivation events including cytomegalovirus reactivation appeared to be more frequent in the abnormal group of T-cell subsets.ConclusionsThe immune recovery status post-allogeneic HSCT was affected by GVHD prophylactic regimens, especially in cases receiving tacrolimus-based GVHD prophylaxis, T-cell depletion, and possibly those manifesting acute GVHD. Delayed immune reconstitution might increase the morbidity due to viral reactivation. Treatment strategies are needed to prevent infectious complications and enhance immune reconstitution based on the immune recovery status following allogeneic HSCT with fludarabine-based conditioning.