Etiology and outcome of graft failure in pediatric hematopoietic stem cell transplant recipients

Two novel assays demonstrate persistent daratumumab exposure in a pediatric patient with delayed engraftment following allogeneic hematopoietic stem cell transplantation

BACKGROUND AIMS

Daratumumab, a human IgG monoclonal antibody targeting CD38, is a promising treatment for pediatric patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL). We describe a case of delayed engraftment following a mismatched, unrelated donor hematopoietic stem cell transplant (HSCT) in a 14-year-old female with relapsed T-ALL, treated with daratumumab and chemotherapy. By Day 28 post-HSCT, the patient had no neutrophil engraftment but full donor myeloid chimerism.

METHODS

We developed two novel, semi-quantitative, antibody-based assays to measure the patient's bound and plasma daratumumab levels to determine if prolonged drug exposure may have contributed to her slow engraftment.

RESULTS

Daratumumab levels were significantly elevated more than 30 days after the patient's final infusion, and levels inversely correlated with her white blood cell counts. To clear daratumumab, the patient underwent several rounds of plasmapheresis and subsequently engrafted.

CONCLUSIONS

This is the first report of both delayed daratumumab clearance and delayed stem cell engraftment following daratumumab treatment in a pediatric patient. Further investigation is needed to elucidate the optimal dosing of daratumumab for treatment of acute leukemias in pediatric populations as well as daratumumab's potential effects on hematopoietic stem cells and stem cell engraftment following allogenic HSCT.

Improvement of survival after hematopoietic stem cell transplantation and trends at a pediatric transplantation center; a three-decade journey

BACKGROUND

Advances in stem cell transplantation have resulted in improved outcomes.

METHODS

This is a retrospective study aimed to analyze changes in patient profile, transplantation, graft characteristics, and outcome among 241 pediatric patients who received stem cell transplantation in a single center between 1993 and 2019.

RESULTS

In the 2010-2019, compared with the 1993-2009 period, a significantly higher 5-year overall survival (60% vs. 44%, p = .022) and an event-free survival (53% vs. 34%, p = .025) were observed. Cumulative incidence of deaths due to relapse or progression between the 1993-2009 and 2010-2019 periods were 33% and 26% respectively (p = .66). Cumulative incidence of non-relapse mortality was significantly higher during the 1993-2009 period compared with the 2010-2019 period for malignant diseases (57.7% vs. 28.3%, p = .007). The overall survival from acute graft-versus-host disease between 1993 and 2009 was 11% versus 46% between 2010 and 2019 (p = .0001). The overall survival from infection in both eras did not show any difference (p = .41).

CONCLUSIONS

Development in transplantation technology has led to a decrease in non-relapse mortality and better control of graft-versus-host disease. However, relapse and infection remained as major causes of death. Studies evaluating institutional trends in patients undergoing HSCT and analyzing their mortality profile, can improve the management of patients, leading to a reduction in transplant-related problems.

Graft failure in allogeneic hematopoietic stem cell recipients: diagnosis and treatment

Graft failure is a group of complications after allogeneic hematopoietic stem cell transplantation, which occurs according to different data up to 30%. The group of complications includes primary and secondary graft failure, primary, secondary and transient poor graft function and graft rejection. Diagnostic difficulties consist in the lack of unified diagnostic criteria accepted in the transplantation community and in the dual interpretation of these complications according to the foreign literature. The purpose of this literature review was to identify the most common criteria of different types of graft failure and determine the tactics of diagnosis and treatment. In this review we analyzed data from various literature sources, gave definitions of graft failure and poor graft function. We analyzed the literature data on the methods used to treat these conditions.

Autologous Recovery With Chromosomal Abnormalities After Unrelated Umbilical Cord Blood Transplantation With Myeloablative Conditioning in a Case of Pediatric Acute Lymphoblastic Leukemia

Detailed case reports of autologous recovery of hematopoiesis after hematopoietic stem cell transplantation with myeloablative conditioning are scarce. We present a rare case of a 3-year-old male with relapsed KMT2A -rearranged acute lymphoblastic leukemia who experienced autologous recovery following secondary engraftment failure after cord blood transplantation with myeloablative conditioning. Similar to prior reports, we detected unusual chromosomal abnormalities, which differed at each bone marrow examination. He remains alive without relapse of acute lymphoblastic leukemia 8 months after cord blood transplantation. As the rate of recurrence or late occurrence of secondary malignant neoplasm remains unclear, careful follow-up is required, especially in pediatric patients.

Graft rejection markers in children undergoing hematopoietic cell transplant for bone marrow failure

CXCL9, BAFF, and sC5b-9 are potential biomarkers and therapeutic targets for graft rejection after transplant.

Fever monitoring is a widely available and informative predictor of graft rejection after transplant.

Graft rejection (GR) is a poorly understood complication of hematopoietic cell transplant (HCT). GR risk factors are well published, but there are no reliable biomarkers or therapies known. Fever is the most common symptom of GR, but no study has evaluated fever kinetics as a diagnostic marker of GR. The objectives of this study were to identify mechanisms, biomarkers, and potential therapies for GR after HCT. Chemokine ligand 9 (CXCL9), B-cell activating factor (BAFF), and complement markers (sC5b-9, C3a, and C5a) were measured in 7 patients with GR and compared with 15 HCT controls. All patients had a diagnosis of aplastic anemia, Fanconi anemia, or genetically undefined chromosomal fragility syndrome. All patients with GR were febrile during GR; therefore, control patients who underwent HCT were matched for diagnosis and early fevers after HCT. Patients withh GR had significantly higher CXCL9, BAFF, and sC5b-9 at the time of fever and GR compared with control patients who underwent HCT at the time of fever. The maximum fever was significantly higher and occurred significantly later in the transplant course in patients with GR compared with febrile HCT controls. These data support the use of CXCL9, BAFF, sC5b-9, and fever kinetics as GR markers. Two patients with GR underwent a second HCT that was complicated by high fevers. Both patients received interferon and complement blockers during their second HCT, and both preserved their graft. These laboratory and clinical findings support larger studies to evaluate the safety and efficacy of interferon, complement, and BAFF inhibitors for the prevention and treatment of GR after HCT.

Graft failure after "ex-vivo" T-cell depleted haploidentical transplantation in pediatric patients with high-risk hematological malignancies. A risk factors and outcomes analysis

Risk factors and outcomes of GF after TCD haploidentical transplantation in children with hematological malignancies were analyzed. 148 TCD transplants were included. 78 patients were diagnosed of ALL and 70 patients of AML. 22 out of 148 patients developed GF. MVA showed that patient <9 years (HR: 5.0; 95% CI: 1.1-23.0; p = 0.03) and pre-transplant CD8+ ≥150/µL (HR: 12.0; 95% CI: 1.6-95.3; p = 0.01) were associated with GF. A score was assigned to each patient. The cumulative incidence of GF for patients with CD8+ ≥150/µL (2 points) was 6 ± 4% and 3 ± 2% for patients <9 years (1 point) while for patients with 3 points was 24 ± 6%, With a median follow-up of 48 months (range; 4-180 months), 14 (64%) of 22 patients with GF are alive and disease-free. DFS for GF patients was 53 ± 12%. In conclusion, patient age and pre-transplant CD3+/CD8+ are associated with GF in children undergoing TCD haploidentical transplantation.

The impact of donor-specific anti-human leukocyte antigen antibodies in salvage haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide in patients with nonmalignant disorders

The presence of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) has been recognized as a major risk factor for graft failure (GF) after haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide (haplo-PTCy). However, the role of DSAs in salvage haplo-PTCy for rescuing patients with nonmalignant disorders (NMDs) has not yet been reported. The present study retrospectively analyzed 22 patients with NMDs who underwent salvage haplo-PTCy from January 2008 to December 2017. The median age at the time of the rescue haplo-PTCy was 9 years (range, 1-26 years). Median time from the first transplant to second haplo-PTCy was 56 days (range, 37-591 days). Among all patients, six (27.3%) had DSAs, with a median DSA strength (mean fluorescence intensity [MFI]) of 5201 (range, 1412-11,543) in the first DSA testing. In addition, the median DSA MFI was 2672 (range, 832-10,498) before the bone marrow infusion. Overall, GF occurred in 5 (25%) of the 20 assessable patients. Three of four (75%) patients with DSAs experienced GF versus 2 of 16 (12.5%) DSA-negative patients (P = 0.032). The median DSA MFI for patients with GF was 6437 (range, 1412-10,498) versus 1845 (range, 832-2672) for those who engrafted or had early death (P = 0.030). One-year event-free survival was significantly lower in DSA-positive patients than in those without DSAs (16.7% vs. 62.5%, P = 0.002). DSA-negative patients had an acceptable 1-year survival of 62.5%. In conclusion, this study suggests that DSAs may be associated with deleterious outcomes after salvage haplo-PTCy in patients with NMDs.

Outcomes of Haploidentical Stem Cell Transplantation using Total Body Irradiation (600 cGy) and Fludarabine with Antithymocyte Globulin in Adult Patients with Severe Aplastic Anemia: A Prospective Phase II Study

The aim of this study was to verify the feasibility of rabbit antithymocyte globulin (ATG; 5 mg/kg) in combination with 600 cGy of fractionated total body irradiation (fTBI; 3 doses of 200 cGy) and fludarabine (Flu; 150 mg/m²) as a conditioning regimen for haploidentical stem cell transplantation from a related mismatched donor (haplo-SCT) in adult patients with severe aplastic anemia (SAA). We analyzed 47 consecutive patients who underwent haplo-SCT, including 24 patients from our previous pilot report. The median age was 36.0 years (range, 17 to 61 years), and 25 patients (53%) were very severe aplastic anemia (VSAA) at transplantation. All patients achieved primary engraftment. The cumulative incidence of grade ≥II acute graft-versus-host disease (GVHD) and chronic moderate or greater GVHD was 27.7% at 100 days and 13.5% at 3 years, respectively. With a median follow-up of 32.3 months, the 3-year probability of overall survival and failure-free survival was 91.0% and 88.6%, respectively. The 3-year GVHD- and failure-free survival (GFFS) was 71.6%. Offspring donor and lower comorbidity index were independent factors correlated with higher GFFS in multivariate analysis. In conclusion, the outcomes of haplo-SCT with fTBI 600 cGy/Flu/ATG-5 indicate that haplo-SCT can be an effective alternative option when a fully matched donor is not available or a patient with VSAA needs an urgent transplantation.

Optimal conditioning regimen for haplo-identical stem cell transplantation in adult patients with acquired severe aplastic anemia: Prospective de-escalation study of TBI and ATG dose

This prospective study explored an optimal conditioning regimen to ensure engraftment with minimal toxicity in adult patients with severe aplastic anemia (SAA) who received haplo-identical stem cell transplantation from a related mismatched donor (Haplo-SCT). We explored a safe and sufficient dose of rabbit ATG (Thymoglobulin) in combination with 800 cGy total body irradiation (TBI) and fludarabine (Flu, 30 mg/m² /day) for 5 days using step-by-step dose de-escalation. The dose of ATG was de-escalated from 10 mg/kg (group 1), to 7.5 mg/kg (group 2), to 5 mg/kg (group 3), and the TBI dose was reduced to 600 cGy (group 4) beginning in October 2014. If one patient developed transplant-related mortality (TRM) with engraftment in a group, we moved to the next lower dose group. Thirty-four patients were enrolled in groups 1-3 (n = 10) and 4 (n = 24). All patients achieved primary engraftment. The incidence of acute GVHD (grade ≥ 2) and chronic GVHD (≥ moderate) was 29.4% and 14.7%, respectively. With a median follow-up of 56.6 and 21.8 months in groups 1-3 and group 4, respectively, the 2-year probability of overall survival (91.7% in group 4 vs 70% in groups 1-3, P = 0.155) and GVHD-free survival (78.4% in group 4 vs 50% in groups 1-3, P = 0.115) was shown tended to be better in group 4. This study explored an optimal conditioning with step-by-step de-escalation dosage of ATG and TBI to reduce TRM with sustained graft function. TBI-600 cGy/Flu/intermediate-dose ATG resulted in feasible outcomes of Haplo-SCT for adult patients with SAA.

Non-myeloablative conditioning for second hematopoietic cell transplantation for graft failure in patients with non-malignant disorders: a prospective study and review of the literature

Allogeneic hematopoietic cell transplantation (HCT) effectively treats several non-malignant disorders such as selected lysosomal disorders, cerebral adrenoleukodystrophy and hemoglobinopathies. However, rates of graft failure (GF) in non-malignant populations exceed those of patients with malignant indications for HCT. Salvage conditioning regimens and outcomes for second HCT for GF vary immensely in the literature. We report 17 consecutive pediatric patients with non-malignant disorders who underwent a second allogenic HCT for GF using a non-myeloablative, low-dose busulfan-based regimen. Graft sources for the second transplant included umbilical cord blood, unrelated bone marrow and unrelated PBSCs. Median age at time of second HCT was 6.6 years (1.1-14.6 years). Fourteen of seventeen patients (82%) achieved engraftment, with a 3-year overall survival of 82% (95% CI, 54-94%). Day 100 transplant-related mortality was 12% (95% CI, 0-27%). CMV and adenovirus reactivation occurred in 30% and fungal infections in 18%. The incidence of grade II-IV acute GvHD disease was 35% (95% CI, 13-58%) with only 6% grade III-IV (95% CI, 0-17%). In summary, we illustrate excellent overall survival and acceptable toxicity using a non-myeloablative conditioning regimen for second HCT as salvage therapy for first GF in patients with non-malignant conditions.

Haplo-identical transplantation for acquired severe aplastic anaemia in a multicentre prospective study

We conducted a prospective, multicentre study to confirm the feasibility of haplo-identical transplantation in treatment of severe aplastic anaemia (SAA) as salvage therapy, by analysing the outcomes of 101 patients who received haplo-identical transplantation between June 2012 and October 2015. All cases surviving for more than 28 d achieved donor myeloid engraftment. The median time for myeloid engraftment was 12 (range, 9-25) days and 15 (range, 7-101) days for platelets, with a cumulative platelet engraftment incidence of 94·1 ± 0·1%. With a median follow-up of 18·3 (3·0-43·6) months, recipients from haplo-identical transplantation had more cumulative incidence of grade II-IV acute graft-versus-host disease (aGVHD, 33·7% vs. 4·2%, P < 0·001), more chronic GVHD (22·4% vs. 6·6%, P = 0·014) at 1 year, but similar grade III-IV aGVHD (7·9% vs. 2·1%, P = 0·157), 3-year estimated overall survival (OS, 89·0% vs. 91·0%, P = 0·555) and failure-free survival (FFS, 86·8% vs. 80·3%, P = 0·659) when compared with 48 patients who received contemporaneous transplantation from matched related donors. Multivariate analysis showed no significant difference in engraftment and survival between the two cohorts. Both OS and FFS for the entire population correlated significantly with grades III-IV aGVHD. In conclusion, haplo-identical transplantation is a feasible choice for SAA with favourable outcomes.

Haploidentical hematopoietic stem cell transplantation in children and adolescents with acquired severe aplastic anemia

Severe aplastic anemia (SAA) is a life-threatening disorder for which allogeneic hematopoietic stem cell transplantation (HSCT) is the current available curative treatment. HSCT from matched sibling donors (MSDs) is the preferred therapy for children with acquired SAA. For patients who lack MSDs, immunosuppressive therapy (IST) is widely accepted as a first-line treatment before considering HCT from an unrelated donor (URD). Given the recent progress in HSCT using URDs for childhood SAA, well-matched URDs became a realistic alternative for pediatric patients who have no suitable related donors and who are refractory to IST. However, it is quite challenging to treat patients with refractory SAA who lack suitable related or URDs. Even though haploidentical HSCT from genetically mismatched family members seemed to be an attractive procedure with the amazing benefit of readily available donors for most patients, early attempts were disappointing because of refractory graft-versus-host disease (GVHD) and excessively high transplant-related mortality. Recent advances with effective ex vivo depletion of T cells or unmanipulated in vivo regulation of T cells, better supportive care, and optimal conditioning regimens have significantly improved the outcome of haploidentical transplant. Besides considerable progress in the treatment of malignant diseases, recent emerging evidences for haploidentical HSCT in SAA has provided additional therapeutic options for patients with refractory diseases. Further improvements to decrease the rates of graft failure, GVHD, and infectious complications will facilitate the emergence of haploidentical HSCT as a front-line therapy for treating acquired SAA in children and adolescents who have no suitably matched donors.

Levetiracetam as a possible cause of secondary graft failure after allogenic hematopoietic stem cell transplantation

BACKGROUND

Levetiracetam is increasingly used as antiepileptic drug (AED) of choice in children as well as in adults with complex diseases due to its lack of interactions and a large spectrum of action. Secondary graft failure, i.e. loss of donor cells after initial engraftment, is a relatively uncommon but serious and life-theatening complication after pediatric hematopoietic stem cell transplantation.

METHODS AND RESULTS

We report a case of secondary graft failure after hematopoietic stem cell transplantation for treatment-related myelodysplastic syndrome during antiepileptic treatment with levetiracetam. Exclusion of all other possible etiologies left levetiracetam as the most likely cause of the imminent complete secondary graft failure after hematopoietic stem cell transplantation. Furthermore, the blood cell count improved just a few days after cessation of levetiracetam medication.

CONCLUSION

Thus, we recommend that in case of secondary graft failure after hematopoietic stem cell transplantation, all possible causes should carefully be excluded, including adverse events through new generation AED agents. Switching to different AEDs with less harming effect on bone marrow function should strongly be considered.

Long-term outcome of HLA-haploidentical hematopoietic SCT without in vitro T-cell depletion for adult severe aplastic anemia after modified conditioning and supportive therapy

HLA-haploidentical hematopoietic SCT (HSCT) is an option for severe aplastic anemia (SAA) patients. Here, we evaluated the outcomes of 26 adult-SAA patients who received HLA-haploidentical HSCT in five transplant centers in southwestern China. Most of the patients in this study failed prior therapy and were transfused heavily before the transplantation. The patients received fludarabine+cyclophosphamide+antithymocyte globulin as conditioning regimens and then unmanipulated peripheral blood plus marrow transplantation. Micafungin, i.v. Ig and recombinant human TPO were used for post-grafting infection prevention and supportive care. Of 26 patients, 25 achieved engraftment at a median of 13 days (range, 11-19 days) after HSCT. One of 25 patients experienced graft rejection and did not achieve sustained engraftment after second HSCT. Therefore, the final engraftment rate was 92.3%. Three of 25 (12%) patients developed acute GVHD, 10 of 25 (40%) patients developed chronic GVHD (9 with limited whereas the other with extensive). The OS rate was 84.6% and the average follow-up time was 1313.2 (738-2005) days for surviving patients. This encouraging result suggests that HLA-haploidentical HSCT is an effective therapeutic option for adults with acquired SAA if an HLA-identical donor is not available.

Post-hematopoietic stem cell transplantion immune-mediated cytopenias

Immune-mediated cytopenias after allogeneic stem cell transplantation can be categorized as either alloimmune when host or donor immunity reacts against donor or host elements, respectively, or autoimmune when donor immunity reacts against donor hematopoietic tissue, owing to poorly understood mechanisms that result in severe impairment of central and peripheral tolerance. Immune cytopenias are manifested as monolineage or more rarely as bilineage cytopenias, and are usually mediated through humoral immune mechanisms. On the contrary, immune-mediated pancytopenia is a rare event with only few cases reported in the literature. The exact pathogenesis of immune pancytopenia is not well known although it is possible that cellular immunity may play a significant role. The importance of these syndromes lies in the fact that they can cause severe morbidity and mortality. Differential diagnosis from other causes of post-transplant pancytopenia is of extreme value because these disorders can respond to various treatment modalities.

Long-term follow-up of patients who experienced graft failure postallogeneic progenitor cell transplantation. Results of a single institution analysis

The long-term outcome of graft failure after allogeneic stem cell transplantation (SCT) has not been well described. To fill this knowledge gap we performed a retrospective analysis of patients with graft failure over a 10-year time period in a single institution. Cases were included for analysis if they had failed to achieve an absolute neutrophil count (ANC) of 500/microL or more by 28 days post-SCT or 42 days after cord blood transplantation (primary graft failure); had a decrease in their ANC to <500/mL for 3 consecutive days after having achieved neutrophil engraftment (secondary graft failure); or failed to have evidence of at least 5% or more donor cell engraftment (primary graft failure with autologous reconstitution). Among 1726 patients who underwent allografts from January 1, 1990, through December 31, 2000, we identified 68 patients with graft failure. The 1-, 2-, and 5-year overall survival (OS) for all patients was 31%, 24%, and 15%. A diagnosis of acute leukemia was a significant predictor for poor survival on multivariate analysis. We conclude that graft failure is an uncommon complication postallogeneic SCT, and is associated with poor outcomes. Collection of autologous stem cells prior to high-risk allografting can salvage a fraction of patients and lead to prolonged survivals.

The harvest and use of autologous back-up grafts for graft failure or severe GVHD after allogeneic hematopoietic stem cell transplantation: a survey of the European Group for Blood and Marrow Transplantation

Autologous hematopoietic stem cells (HSCs) harvested as back-up prior to allogeneic hematopoietic SCT (HSCT) may potentially be useful in the treatment of graft failure or in cases with severe GVHD. Here, we studied the general policies and indications for autologous back-up harvest among the European Group for Blood and Marrow Transplantation centers in the year 2003. The outcome of patients receiving autologous back-up transfusion between 1998 and 2002 was evaluated retrospectively. The responses from 94 centers showed that 48 centers had a general policy with variable indications for autologous back-up harvest. Thirty-five patients with graft failure (25), GVHD (8) or relapse (2) retransplanted with autologous back-ups were reported. Autologous back-up transfusion was performed at a median of 35 days (patients with graft failure) or 90 days (patients with GVHD) after allogeneic HSCT. Within 100 days after autologous HSCT, 21 patients died from treatment-related complications (19) or relapse (2). Estimated overall survival at 1 year was 16% (95% CI 0-32%) for patients treated for graft failure and 13% (95% CI 0-37%) for GVHD patients. In conclusion, our data demonstrate that the indication for autologous back-up harvests is limited and that general storage and use cannot be recommended unless in selected prospective studies.

Retransplantation with stem cells from mismatched related donors after graft rejection in pediatric patients

Graft failure is a life-threatening complication after transplantation of hematopoietic stem cells. We report a cohort of 11 pediatric patients with leukemias (n=8) and severe aplastic anemia (n=3) who experienced graft rejection after myeloablative transplantation from mismatched related donors (n=6) or after cord blood or matched unrelated donor transplantation (n=5). In the latter, the original donor was not available anymore. All patients were re-transplanted with CD34(+) selected or CD3/CD19 depleted stem cells from a second, haploidentical donor. Median time span from diagnosis of rejection to second transplant was 9 days. Reconditioning regimens comprised total lymphoid irradiation, thiotepa, fludarabine, ATG/OKT3 and were well tolerated. A median number of 23.5x10(6)/kg stem cells with 95,000/kg residual T-cells were infused. Sustained engraftment of neutrophiles/platelets and complete donor chimerism was achieved in all patients (ANC>500/microl: 9 (11-32) days). No GvHD>grade II was observed. 8/11 patients are disease free (median follow up 1.9 years; 1 year-EFS=72%). Causes of death were: pneumonitis, infection, relapse. Thus, haploidentical transplantation represents a realistic option to rescue patients with graft failure within a short time span, for whom a second donation from the original donor is not available. The use of different donors may contribute to avoid a second rejection.

Normal hematopoietic function and multiple bone marrow clonal abnormalities in a patient with acute myeloid leukemia after two mismatched stem-cell transplants with graft failure and autologous reconstitution

A 13-year-old male with primary refractory acute myelogenous leukemia (AML-M0), underwent two mismatched stem cell transplantations (SCT) and experienced graft failure after both procedures. Of interest, his peripheral blood cell counts are normal 7 years after his first SCT, his bone marrow is morphologically normal, however, cytogenetic analysis reveals multiple recurring cytogenetic abnormalities. This is the third case of chromosomal instability with morphological normal marrow and peripheral blood to be reported, these rare cases suggest that hematopoietic stem cells must have compensating mechanisms that allow normal function despite extensive chromosomal damage, supporting the notion that normal marrow function is possible even with extensive chromosomal damage.

Reduced intensity conditioning in unrelated donor transplantation for refractory cytopenia in childhood

Myelodysplastic syndromes (MDS) are a heterogenous group of acquired hematopoietic stem cell disorders. Refractory cytopenia (RC) is the most common subtype of childhood MDS and hematopoietic stem cell transplantation (HSCT) is the only curative treatment. HSCT following a myeloablative preparative regimen is associated with a low probability of relapse and considerable transplant-related mortality. In the present European Working Groups of MDS pilot study, we investigated whether a reduced intensity conditioning regimen (RIC) is able to offer reduced toxicity without increased rates of graft failure or relapse. Nineteen children with RC were transplanted from an unrelated donor following RIC consisting of fludarabine, thiotepa and anti-thymocyte globulin. Three patients experienced graft failure. Neutrophil and platelet engraftment occurred at a median time of 23 and 30 days, respectively. Cumulative incidence of grade II-IV and grade III and IV acute graft-versus-host disease (GVHD) was 0.48 and 0.13, respectively; three patients developed extensive chronic GVHD. Although infections were the predominant complications, only one patient with extensive chronic GVHD died from infectious complications. Overall and event-free survival at 3 years were 0.84 and 0.74, respectively. In conclusion, our results were comparable to those of patients treated with myeloablative HSCT. Long-term follow-up is needed to demonstrate the expected reduction in long-term sequelae.

Extracorporeal membrane oxygenation for support of children after hematopoietic stem cell transplantation: the Extracorporeal Life Support Organization experience

PURPOSE

Extracorporeal membrane oxygenation (ECMO) is a means of respiratory and hemodynamic support for patients failing conventional therapies. Children requiring hematopoietic stem cell transplantation who develop complications during therapy may require ECMO. Such patients pose medical and ethical challenges for clinicians considering initiation of ECMO. The authors review the outcomes of these patients and propose recommendations.

METHODS

The Extracorporeal Life Support Organization Registry was queried for all patients younger than 18 years with an International Classification of Diseases, Ninth Revision, or Current Procedural Terminology code related to bone or stem cell transplant.

RESULTS

Nineteen children in the registry met inclusion criteria. The median age was 9.6 years (7 months to 17.5 years). Initiation of ECMO was for pulmonary support (n = 17), cardiac support (n = 1), or cardiopulmonary resuscitation (n = 1). The median duration of ECMO support was 5.1 days (range, 30 hours to 42 days). Pulmonary infections included 3 parainfluenza, 2 Pneumocystis carinii, 1 influenza A, and 1 respiratory syncytial virus. Overall, 15 (79%) died during their ECMO run, whereas only 4 (21%) survived to come off ECMO. Furthermore, of those who survived their ECMO run, only one patient survived to discharge from the hospital. Risk factors for death on ECMO include development of renal complications and development of multiorgan dysfunction.

CONCLUSION

Patients who require ECMO for cardiopulmonary support after hematopoietic stem cell transplantation have a poor prognosis. Clinicians must be cautious in presenting this option to parents and present them with appropriate expectations in this high-risk population.