Outcomes after Second Hematopoietic Stem Cell Transplantations in Pediatric Patients with Relapsed Hematological Malignancies

Disease Status and Interval between Hematopoietic Cell Transplantations Predict Outcome of Pediatric Patients Who Undergo Subsequent Transplantation for Relapsed Hematologic Malignancy

Patients with hematologic malignancies who relapse after allogeneic hematopoietic cell transplantation (HCT) have a poor prognosis. Although proceeding to subsequent HCT can provide potential for long-term survival, there are limited data to guide which patients are most likely to benefit and which HCT strategies are best in this heavily pretreated population. The goals of this study were to describe the clinical outcomes of subsequent HCT in pediatric patients with relapsed hematologic malignancies in a cohort enriched for haploidentical donors, and to evaluate the associations of patient-, disease-, and treatment-related factors with survival. We retrospectively evaluated patients who underwent a subsequent HCT for management of post-HCT relapse at a single institution between 2000 and 2021. Among 106 patients who underwent a second allogeneic HCT, the 1-year event-free survival (EFS) was 34% and 1-year overall survival (OS) was 46%, with a 5-year EFS of 26% and 5-year OS of 31%. Only disease-related factors were associated with outcome after second HCT-specifically, the interval between HCTs and the presence or absence of active disease at the time of HCT. In this cohort, patient- and treatment-related factors were not associated with differences in EFS or OS. Patients undergoing a third or fourth HCT (n = 13) had comparable survival outcomes to those undergoing a second HCT. Our experience highlights that a subsequent HCT has curative potential for a subset of patients who relapse after HCT, including those who undergo a subsequent HCT from a haploidentical donor. Although relapse and treatment-related toxicities remain major challenges, our study indicates that achieving complete remission prior to subsequent HCTs has the potential to further improve outcomes.

Recurrent thoracic air leak syndrome in patients affected by pulmonary graft-versus-host disease: Surgical strategies and outcome

BACKGROUND AND AIMS

Thoracic air leak syndrome (TALS) is a complication related to chronic pulmonary graft-versus-host disease (pGvHD) that affects approximately 0.83%-3.08% patients after allogenic hematopoietic stem cell transplant. Such complication is defined as the occurrence of any form of air leak in the thorax, including spontaneous pneumomediastinum or pneumopericardium, subcutaneous emphysema, interstitial emphysema and pneumothorax and has a negative impact on post-transplant survival. The aim of the present study is to describe a single-center experience in the surgical management of recurrent TALS in adolescents and young adults and its outcome.

METHODS

We retrospectively reviewed the clinical notes of patients with previous allogenic hematopoietic stem cell transplant who underwent surgical procedures for recurrent TALS from January 2016 until March 2021. We analyzed clinical data, number of episodes of thoracic air leak, surgical procedures and relative outcome.

RESULTS

In the examined period, four patients, aged 16-25 years, underwent surgical procedures for TALS, including thoracostomy tube placement, thoracoscopic pleurodesis and thoracotomy. All the patients had been diagnosed with pGvHD before the onset of TALS, with a mean time lapse of 276 days (range 42-513). These patients experienced on average 4.5 air leak episodes (range 3-6). All the patients experienced at least two episodes before surgery. One patient underwent emergency tube thoracostomy only, three patients underwent thoracoscopic pleurodesis and two patients underwent thoracotomy. After surgery, patients were free from air leak symptoms for a mean time of 176 days (range 25-477). Pulmonary function progressively deteriorated, and all the patients eventually died because of respiratory failure after a mean time of 483 days (range 127-1045) after the first episode of air leak.

CONCLUSIONS

Surgery provides temporary relief to symptoms related to TALS but has limited effects on the underlying pathophysiologic process. The development of TALS in a sign of progressive pulmonary function worsening and is associated with high risk of respiratory failure and mortality.

Sub-myeloablative Second Transplantations with Haploidentical Donors and Post-Transplant Cyclophosphamide have limited Anti-Leukemic Effects in Pediatric Patients

Pediatric patients with high-risk hematologic malignancies who experience relapse after a prior allogeneic hematopoietic cell transplant (HCT) have an exceedingly poor prognosis. A second allogeneic HCT offers the potential for long-term cure but carries high risks of both subsequent relapse and HCT-related morbidity and mortality. Using haploidentical donors for HCT (haploHCT) can expand the donor pool and potentially enhance the graft-versus-leukemia effect but is accompanied by a risk of graft-versus-host disease (GVHD). The goal of this protocol was to intensify the antileukemia effect of haploHCT for pediatric patients with hematologic malignancies that relapsed after prior allogeneic HCT, while limiting regimen-associated toxicities. This phase II clinical trial evaluated a sub-myeloablative preparative regimen consisting of anti-thymocyte globulin, clofarabine, cytarabine, busulfan, and cyclophosphamide, in combination with plerixafor to sensitize leukemic blasts. Participants received a mobilized peripheral blood unmanipulated haploidentical donor graft with one dose of post-transplant cyclophosphamide as GVHD prophylaxis, followed by natural killer (NK) cell addback. Here we report the clinical outcomes and immune reconstitution of 17 participants treated on the study and 5 additional patients treated on similar single-patient treatment plans. Of the 22 participants analyzed, 12 (55%) had active disease at the time of HCT. The regimen provided robust immune reconstitution, with 21 participants (95%) experiencing neutrophil engraftment at a median of 14 days after HCT. In this high-risk population, the overall survival was 45% (95% confidence interval [CI], 24%-64%), with a 12-month event-free survival of 31% (95% CI, 14%-51%) and cumulative incidence of relapse at 12 months of 50% (95% CI, 27%-69%). Four participants (18%) remain in remission at >5 years follow-up. Expected HCT-related organ-specific toxicities were observed, and 13 participants (59%) experienced acute or chronic GVHD. This intensified but sub-myeloablative regimen, followed by a high-dose unmanipulated haploidentical graft, post-transplantation cyclophosphamide, and NK cell infusion, resulted in adequate immune reconstitution but failed to overcome the elevated risks of relapse and treatment-related morbidity in this high-risk population.

Outcome of donor-derived TAA-T cell therapy in patients with high-risk or relapsed acute leukemia post allogeneic BMT

Patients with hematologic malignancies relapsing after allogeneic blood or marrow transplantation (BMT) have limited response to conventional salvage therapies, with an expected 1-year overall survival (OS) of <20%. We evaluated the safety and clinical outcomes following administration of a novel T-cell therapeutic targeting 3 tumor-associated antigens (TAA-T) in patients with acute leukemia who relapsed or were at high risk of relapse after allogeneic BMT. Lymphocytes obtained from the BMT donor were manufactured to target TAAs WT1, PRAME, and survivin, which are over-expressed and immunogenic in most hematologic malignancies. Patients received TAA-T infusions at doses of 0.5 to 4 × 107/m2. Twenty-three BMT recipients with relapsed/refractory (n = 11) and/or high-risk (n = 12) acute myeloid leukemia (n = 20) and acute lymphoblastic leukemia (n = 3) were infused posttransplant. No patient developed cytokine-release syndrome or neurotoxicity, and only 1 patient developed grade 3 graft-versus-host disease. Of the patients who relapsed post-BMT and received bridging therapy, the majority (n = 9/11) achieved complete hematologic remission before receiving TAA-T. Relapsed patients exhibited a 1-year OS of 36% and 1-year leukemia-free survival of 27.3% post-TAA-T. The poorest prognosis patients (relapsed <6 months after transplant) exhibited a 1-year OS of 42.8% postrelapse (n = 7). Median survival was not reached for high-risk patients who received preemptive TAA-T posttransplant (n = 12). Although as a phase 1 study, concomitant antileukemic therapy was allowed, TAA-T were safe and well tolerated, and sustained remissions in high-risk and relapsed patients were observed. Moreover, adoptively transferred TAA-T detected by T-cell receptor V-β sequencing persisted up to at least 1 year postinfusion. This trial was registered at clinicaltrials.gov as #NCT02203903.

Hematopoietic Cell Transplantation-Comorbidity Index Score Is Correlated with Treatment-Related Mortality and Overall Survival following Second Allogeneic Hematopoietic Cell Transplantation in Children

Allogeneic hematopoietic cell transplantation (HCT) can lead to considerable complications and treatment-related mortality (TRM); therefore, a detailed assessment of risks is essential. The Hematopoietic Cell Transplantation-Comorbidity Index (HCT-CI) can predict both TRM and overall survival (OS). Although the HCT-CI has been validated as a useful tool for first HCT, its potential utility for second HCT has not yet been investigated. Here we aimed to evaluate the utility of the HCT-CI score in assessing the risk of TRM and OS in the setting of a second allogeneic HCT. This was a retrospective analysis of all pediatric patients (age <21 years) who underwent a second allogeneic HCT at UCSF Benioff Children's Hospital San Francisco between 2008 and 2019. According to their HCT-CI, patients were classified as "low risk" with an HCT-CI of 0 or "intermediate-high risk" with an HCT-CI ≥1. A total of 59 patients were included in the study. Our primary endpoint was TRM, observed at 100 days, 180 days, 1 year, and last follow-up following HCT, and our secondary endpoint was OS at 1 year and at 5 years or last follow-up. We also evaluated outcomes of patients admitted to the pediatric intensive care unit based on the HCT-CI score. Seventy-six percent of patients had an HCT-CI of 0. The most frequent comorbidities were pulmonary, seen in 7 patients (12%; 95% CI, 5% to 23%), including 5 (71%) with moderate and 2 (29%) with severe comorbidities. The OS and the cumulative incidence of TRM at 1 year for the entire cohort were 81% (95% CI, 69% to 90%) and 12% (95% CI, 5% to 22%), respectively. The cumulative incidence of TRM and OS at 1 year showed a significant correlation with HCT-CI score; TRM was 4% (95% CI, 1% to 13%) for an HCT-CI of 0 versus 36% (95% CI, 13% to 60%) for an HCT-CI ≥1 (P < .001), and OS was 89% (95% CI, 75% to 99%) for an HCT-CI of 0 versus 57% (95% CI, 28% to 78%) for an HCT-CI ≥1 (P = .003). After adjusting for covariates, HCT-CI continued to be associated with both TRM (P = .004) and OS (P = .003). In addition, comparing patients with malignancies and nonmalignant disorders, disease-free-survival at last follow-up was higher in the nonmalignant disorder group and also was influenced by the HCT-CI score in each group (P = .0035). There also was a significant difference in outcomes of patients admitted to the pediatric intensive care unit; 15 patients (68%) with an HCT-CI of 0 were alive at last follow-up, compared with only two (22%) with an HCT-CI ≥1 (P = .016). HCT-CI has an impact on TRM and OS and may serve as a predictor of outcomes of second allogeneic transplantation. Although this study was conducted in a relatively small sample, it is the first to investigate the utility of the HCT-CI score in predicting outcomes after a second allogeneic HCT in pediatric recipients. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Effects of second transplantation with T-cell-replete haploidentical graft using low-dose anti-thymocyte globulin on long-term overall survival in pediatric patients with relapse of leukemia after first allogeneic transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the preferred treatment for children with high-risk hematologic malignancies, but post-allo-HSCT relapse has a poor prognosis and limited treatment options. We evaluated the feasibility, outcome, and risk factors influencing survival after T-cell-replete haploidentical HSCT with low-dose anti-thymocyte globulin (ATG) in 30 patients with post-allo-HSCT relapse of acute lymphoblastic leukemia and acute myeloid leukemia. Overall, 50% of the patients had complete remission (CR) before the second transplant and the overall survival (OS) rate was 52%. In surviving patients (median follow-up 614 days), Kaplan-Meier analysis revealed estimated 2-year leukemia-free survival and OS rates of 48.1% and 61.1%, respectively. Cumulative incidences of 2-year non-relapse mortality and relapse were 24.7% and 36.3%, respectively. Achieving CR before the second allo-HSCT was a predominant independent prognostic factor identified in the multivariate analysis, with a significantly improved 2-year OS rate of 86.7%. T-cell-replete haplo-HSCT with low-dose ATG for second allo-HSCT may benefit a selected patient population.

The Role of Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) offers potentially curative treatment for many children with high-risk or relapsed acute leukemia (AL), thanks to the combination of intense preparative radio/chemotherapy and the graft-versus-leukemia (GvL) effect. Over the years, progress in high-resolution donor typing, choice of conditioning regimen, graft-versus-host disease (GvHD) prophylaxis and supportive care measures have continuously improved overall transplant outcome, and recent successes using alternative donors have extended the potential application of allotransplantation to most patients. In addition, the importance of minimal residual disease (MRD) before and after transplantation is being increasingly clarified and MRD-directed interventions may be employed to further ameliorate leukemia-free survival after allogeneic HSCT. These advances have occurred in parallel with continuous refinements in chemotherapy protocols and the development of targeted therapies, which may redefine the indications for HSCT in the coming years. This review discusses the role of HSCT in childhood AL by analysing transplant indications in both acute lymphoblastic and acute myeloid leukemia, together with current and most promising strategies to further improve transplant outcome, including optimization of conditioning regimen and MRD-directed interventions.

Prognostic factors for survival in children who relapsed after allogeneic hematopoietic stem cell transplantation for acute leukemia

BACKGROUND

Post-transplant relapse has a dismal prognosis in children with acute leukemia undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Data on risk factors, treatment options, and outcomes are limited.

PROCEDURE

In this retrospective multicenter study in which a questionnaire was sent to all pediatric transplant centers reporting relapse after allo-HSCT for a cohort of 938 children with acute leukemia, we analyzed 255 children with relapse of acute leukemia after their first allo-HSCT.

RESULTS

The median interval from transplantation to relapse was 180 days, and the median follow-up from relapse to the last follow-up was 1844 days. The 3-year overall survival (OS) rate was 12.0%. The main cause of death was disease progression or subsequent relapse (82.6%). The majority of children received salvage treatment with curative intent without a second HSCT (67.8%), 22.0% of children underwent a second allo-HSCT, and 10.2% received palliative therapy. Isolated extramedullary relapse (hazard ratio (HR): 0.607, P = .011) and relapse earlier than 365 days post-transplantation (HR: 2.101, P < .001 for 0-180 days; HR: 1.522, P = .041 for 181-365 days) were found in multivariate analysis to be significant prognostic factors for outcome. The type of salvage therapy in chemosensitive relapse was identified as a significant prognostic factor for OS.

CONCLUSION

A salvage approach with curative intent may be considered for patients with post-transplant relapse, even if they relapse in the first year post-transplantation. For sustainable remission, a second allo-HSCT may be recommended for patients who achieve complete remission after reinduction treatment.

Have CD19-directed immunotherapy and haploidentical hematopoietic cell transplantation transformed pediatric B-cell acute lymphoblastic leukemia into a chronic disease?

The treatment of pediatric B-cell acute lymphoblastic leukemia (B-ALL) has undergone several recent advancements, leading to an increased amount of treatment options for relapsed patients. The development of immunotherapies such as anti-CD19 chimeric antigen receptor(CAR) T cells and bispecific T-cell engagers has given clinicians therapeutic options with less expected toxicity when compared to standard re-induction chemotherapy. This is especially beneficial in patients with toxicities from their prior treatment. Along with this, the emergence of haploidentical hematopoietic cell transplantation (HCT) has increased opportunity for patients to receive HCT who may not have had an available matched donor. We present four patients who have received all of these therapies in different combinations to treat multiple relapses. Because of the success of achieving remission as well as decreasing toxicity, the patients are alive and well up to 15 y after the original B-ALL diagnosis, rendering this as a chronic disease for them.

Second unmanipulated allogeneic transplantation could be used as a salvage option for patients with relapsed acute leukemia post-chemotherapy plus modified donor lymphocyte infusion

Relapse is the main problem after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The outcome of a second allo-HSCT (HSCT2) for relapse post-HSCT has shown promising results in some previous studies. However, little is known about the efficacy of HSCT2 in patients with relapsed/refractory acute leukemia (AL) post-chemotherapy plus modified donor lymphocyte infusion (post-Chemo + m-DLI) after the first allo-HSCT (HSCT1). Therefore, we retrospectively analyzed the efficacy of HSCT2 in 28 patients with relapsed/refractory AL post-Chemo + m-DLI in our center. With a median follow-up of 918 (457-1732) days, 26 patients (92.9%) achieved complete remission, and 2 patients exhibited persistent disease. The probabilities of overall survival (OS) and disease-free survival (DFS) 1 year after HSCT2 were 25.0% and 21.4%, respectively. The cumulative incidences of nonrelapse mortality on day 100 and at 1 year post-HSCT2 were 7.1% ± 4.9% and 25.0% ± 8.4%. The cumulative incidences of relapse were 50.0% ± 9.8% and 53.5% ± 9.9% at 1 and 2 years post-HSCT2, respectively. Risk stratification prior to HSCT1 and percentage of blasts before HSCT2 were independent risk factors for OS post-HSCT2, and relapse within 6 months post-HSCT1 was an independent risk factor for DFS and relapse post-HSCT2. Our findings suggest that HSCT2 could be a salvage option for patients with relapsed AL post-Chemo + m-DLI.

Outcomes of pediatric patients who relapse after first HCT for acute leukemia or MDS

Disease relapse remains a major cause of treatment failure in patients receiving allogeneic hematopoietic cell transplantation (alloHCT) for high-risk acute leukemias or myelodysplastic syndromes (MDS). Comprehensive data on outcomes after post-transplant relapse are lacking, especially in pediatric patients. Our objective was to assess the impact of various transplant-, patient-, and disease-related variables on survival and outcomes in patients who relapse after alloHCT. We describe our institutional experience with 221 pediatric patients who experienced disease relapse after their first alloHCT for acute leukemias or MDS between 1990 and 2018. In a multivariable model, being in first complete remission at first alloHCT, longer duration of remission after alloHCT, experiencing GVHD and receiving a transplant in a more recent time period were significantly associated with a higher likelihood of receiving a second alloHCT after post-transplant relapse. Of these variables, only longer interval from alloHCT to relapse, receiving a second alloHCT or DLI, and receiving a transplant in a more recent time period were associated with improved overall survival. Our data support pursuing second alloHCT for patients who have experienced relapse after their first transplant, as that remains the only salvage modality with a reasonable chance of inducing long-term remission.

How I treat relapsed acute lymphoblastic leukemia in the pediatric population

Relapsed acute lymphoblastic leukemia (ALL) has remained challenging to treat in children, with survival rates lagging well behind those observed at initial diagnosis. Although there have been some improvements in outcomes over the past few decades, only ∼50% of children with first relapse of ALL survive long term, and outcomes are much worse with second or later relapses. Recurrences that occur within 3 years of diagnosis and any T-ALL relapses are particularly difficult to salvage. Until recently, treatment options were limited to intensive cytotoxic chemotherapy with or without site-directed radiotherapy and allogeneic hematopoietic stem cell transplantation (HSCT). In the past decade, several promising immunotherapeutics have been developed, changing the treatment landscape for children with relapsed ALL. Current research in this field is focusing on how to best incorporate immunotherapeutics into salvage regimens and investigate long-term survival and side effects, and when these might replace HSCT. As more knowledge is gained about the biology of relapse through comprehensive genomic profiling, incorporation of molecularly targeted therapies is another area of active investigation. These advances in treatment offer real promise for less toxic and more effective therapy for children with relapsed ALL, and we present several cases highlighting contemporary treatment decision-making.

Role of a second transplantation for children with acute leukemia following posttransplantation relapse: a study by the Turkish Bone Marrow Transplantation Study Group

We examined outcomes of 51 pediatric patients with relapsed acute leukemia (AL) who underwent a second allogeneic hematopoietic stem cell transplantation (alloHSCT). After a median follow-up of 941 days (range, 69-2842 days), leukemia-free survival (LFS) and overall survival (OS) at 3 years were 26.6% and 25.6%, respectively. The nonrelapse mortality rate (NMR) and cumulative incidence of relapse (CIR) were 36.4% and 42.4%, respectively. The Cox regression analysis demonstrated that the risk factors at second transplantation for predicting limited LFS were active disease (hazard ratio (HR) = 5.1), reduced intensity conditioning (RIC) (HR = 5.0), matched unrelated donor (MUD) (HR = 3.4) and performance score <80 (HR = 3.2). Pediatric patients with AL who relapsed after their first alloHSCT may survive with a second alloHSCT. Disease status, conditioning intensity, donor type, and performance score at the second transplantation are the relevant risk factors. A score based on these factors may predict the results of the second transplantation.

[Effects of chemotherapy combined with donor lymphocyte infusion on chronic graft-versus-host disease and prognosis in minimal residual disease positive patients after allogeneic hematopoietic stem cell transplantation]

Objective: To explore clinical features and severity of chronic graft- versus- host disease (cGVHD) after chemotherapy plus donor lymphocyte infusion (Chemo-DLI) in a consecutive cohort of acute leukemia patients who were minimal residual disease (MRD) positive after allogeneic hematopoietic stem cell transplantation (allo-HSCT) . Methods: The global scoring system proposed by National Institutes of Health (NIH) Consensus Conference was used to identify the characteristics and severity of cGVHD in patients who MRD positive after Chemo-DLI. Results: 54 (59.3%) patients were diagnosed with cGVHD after Chemo-DLI, with the median time of onset of 70 (13-504) days. There were 6 cases (6.6%) of mild cGVHD, 21 cases (23.1%) of moderate cGVHD and 27 cases (29.7%) of severe cGVHD.The 5-year cumulative incidence of relapse after Chemo-DLI was 61.9% (95%CI 45.3%-78.5%) , 15.1% (95%CI 1.1%-29.1%) , and 26.6% (95%CI 9.2%-44.0%) (χ(2)=18.901, P<0.001) in non-cGVHD, mild to moderate cGVHD, and severe cGVHD groups, respectively. The 5-year cumulative incidence of relapse after Chemo-DLI was 61.9% (95%CI 45.3%-78.5%) , 19.9% (95%CI 8.1%-31.7%) , and 28.6% (95%CI 0.0%-65.0%) (χ(2)=18.307, P<0.001) in non-cGVHD, classical cGVHD, and overlap syndrome groups, respectively. cGVHD was not associated with non-relapse morality after Chemo-DLI. Probabilities of 5-year leukemia-free survival (LFS) after Chemo-DLI were 24.0% (95%CI 9.1%-38.9%) , 77.2% (95%CI 60.8%-93.6%) , and 64.9% (95%CI 45.7%-84.1%) (χ(2)=24.447, P<0.001) in non-cGVHD, mild to moderate cGVHD, and severe cGVHD groups, respectively. Probabilities of 5-year LFS after Chemo-DLI were 24.0% (95%CI 9.1%-38.9%) , 75.5% (95%CI 62.7%-88.3%) , and 42.9% (95%CI 1.8%-84.0%) (χ(2)=25.665, P<0.001) in non-cGVHD, classical cGVHD, and overlap syndrome groups, respectively. Probabilities of 5-year overall survival (OS) after Chemo-DLI were 50.0% (95%CI 31.1%-68.9%) , 87.9% (95%CI 74.7%-100.0%) , and 71.0% (95%CI 52.0%-90.0%) (χ(2)=9.517, P=0.009) in non-cGVHD, mild to moderate cGVHD, and severe cGVHD groups, respectively. Probabilities of 5-year OS after Chemo-DLI were 50.0% (95%CI 31.1%-68.9%) , 83.9% (95%CI 72.8%-95.0%) , and 51.4% (95%CI 6.2%-96.6%) (χ(2)=10.673, P=0.005) in non-cGVHD, classical cGVHD, and overlap syndrome groups, respectively. In multivariate analysis, patients receiving allo-HSCT in first complete remission stage and classical cGVHD after Chemo-DLI were associated with lower relapse risk and better survival. Conclusions: These findings highlight the close relation between cGVHD and the graft-versus-leukemia effect in patients who were MRD positive and received Chemo-DLI after allo-HSCT. However, overlap syndrome could not improve the clinical outcomes of these patients.

Improving CAR T cell immunotherapy-mediated remissions for pediatric leukemia

Chimeric antigen receptor (CAR) T cells are an effective therapy for relapsed or refractory pediatric B cell leukemia. Analysis of the starting material, the T cells collected from the patient prior to CAR manufacture, reveals possible biomarkers of cells destined to perform poorly in patients. Long-term follow-up shows that long periods of B cell aplasia, a marker of in vivo CAR activity, are associated with longer remission but also a higher chance of antigen-negative relapse. The role of transplantation as consolidative therapy is unclear in this nonrandomized data, but clearly warrants further study.

Outcomes after Second Hematopoietic Cell Transplantation in Children and Young Adults with Relapsed Acute Leukemia

Children with acute leukemia who relapse after hematopoietic cell transplantation (HCT) have few therapeutic options. We studied 251 children and young adults with acute myelogenous or lymphoblastic leukemia who underwent a second HCT for relapse after their first HCT. The median age at second HCT was 11 years, and the median interval between first and second HCT was 17 months. Most of the patients (n = 187; 75%) were in remission, received a myeloablative conditioning regimen (n = 157; 63%), and underwent unrelated donor HCT (n = 230; 92%). The 2-year probability of leukemia-free survival (LFS) was 33% after transplantation in patients in remission, compared with 19% after transplantation in patients not in remission (P = .02). The corresponding 8-year probabilities were 24% and 10% (P = .003). A higher rate of relapse contributed to the difference in LFS. The 2-year probability of relapse after transplantation was 42% in patients in remission and 56% in those in relapse (P = .05). The corresponding 8-year probabilities were 49% and 64% (P = .04). These data extend the findings of others showing that patients with a low disease burden are more likely to benefit from a second transplantation. Late relapse led to a 10% decrement in LFS beyond the second year after second HCT. This differs from first HCT, in which most relapses occur within 2 years after HCT.

Second Hematopoietic Stem Cell Transplantation for Post-Transplantation Relapsed Acute Leukemia in Children: A Retrospective EBMT-PDWP Study

Outcome data were collected from the European Society for Blood and Marrow Transplantation registry on 373 children from 120 centers with relapsed leukemia (214 with acute lymphoblastic leukemia [ALL] and 159 with acute myelogenous leukemia [AML]) who underwent second allogeneic hematopoietic stem cell transplantation (HSCT) between 2004 and 2013. Overall survival (OS) was 38% at 2 years and 29% at 5 years, and leukemia-free survival (LFS) was 30% at 2 years and 25% at 5 years. Median follow-up after second HSCT was 36.4 months in the ALL group and 50.2 months in the AML group. In the ALL group, OS was 43% at 2 years and 33% at 5 years, and LFS was 34% at 2 years and 31% at 5 years. In the AML group, OS was 32% at 2 years and 24% at 5 years, and LFS was 24% at 2 years and 17% at 5 years. The 2-year nonrelapse mortality (NRM) rate was 22% in the ALL group and 18% in the AML group. Favorable prognostic factors (P < .05) for OS and LFS included >12 months between transplantations and chronic graft-versus-host disease after the first HSCT (in both groups), complete response before the second HSCT (ALL group only), and age >12 years (AML group only). Findings were more consistent over time in the ALL group, with no significant differences between 2-year and 5-year rates of relapse, NRM, and LFS. Children with relapsed acute leukemias have a substantial likelihood of long-term survival following second HSCT. Given the many novel targeted and immunomodulation therapies currently under development, it is important to identify specific patient subpopulations that may benefit from a second HSCT compared with those better suited to new approaches.

Second Allogeneic Stem Cell Transplantation for Acute Leukemia Using a Chemotherapy-Only Cytoreduction with Clofarabine, Melphalan, and Thiotepa

Relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT) remains one of the leading causes of mortality in patients with leukemia. Treatment options in this population remain limited, with concern for both increased toxicity and further relapse. We treated 18 patients with acute leukemia for marrow ± extramedullary relapse after a previous alloHSCT with a myeloablative cytoreductive regimen including clofarabine, melphalan, and thiotepa followed by a second or third transplantation from the same or a different donor. All patients were in remission at the time of the second or third transplantation. All evaluable patients engrafted. The most common toxicity was reversible transaminitis associated with clofarabine. Two patients died from transplantation-related causes. Seven patients relapsed after their second or third transplanation and died of disease. Nine of 18 patients are alive and disease free, with a 3-year 49% probability of overall survival (OS). Patients whose remission duration after initial alloHSCT was >6 months achieved superior outcomes (3-year OS, 74%, 95% confidence interval, 53% to 100%), compared with those relapsing within 6 months (0%) (P < .001). This new cytoreductive regimen has yielded promising results with acceptable toxicity for second or third transplantations in patients with high-risk acute leukemia who relapsed after a prior transplantation, using various graft and donor options. This approach merits further evaluation in collaborative group studies.

Factors associated with improved outcomes after second allogeneic hematopoietic cell transplantation for relapsed pediatric leukemia

A second allogeneic (allo) hematopoietic cell transplant (HCT) is an important therapeutic consideration for patients relapsing after their first. We conducted a retrospective review of 41 pediatric patients with leukemia that underwent a second allo-HCT at our institution. Overall, 53.7 and 43.9 % of patients were alive and disease-free at 1 and 5 years, respectively, after the second allo-HCT. The factors affecting outcome by both univariate and multivariate analysis were interval between transplants and the use of a myeloablative conditioning (MAC) regimen prior to second transplant. Outcomes were inferior in patients who received their second transplant <6 months from their first HCT when compared to patients in whom the interval between HCTs was 6-12 or more than 12 months. Interval between HCTs was also significant when each type of leukemia (acute lymphoblastic leukemia (ALL) n = 21, acute myelogenous leukemia (AML) n = 11, and chronic myelogenous leukemia (CML) n = 7) was analyzed separately. In univariate analysis, use of the same donor and use of a matched sibling donor resulted in significant improved outcome. There was not a significant association between disease-free survival (DFS) and age, remission status, use of total body irradiation (TBI) before second HCT, or type of leukemia. Second allogeneic HCT can be a curative therapeutic option for leukemia patients relapsing after their first transplant. As more targeted therapies have become available, patients that relapse after first HCT are more likely to achieve remission. Therefore, it is anticipated that there will be more candidates for second HCT with improved performance and remission status, ultimately leading to a better outcome with the second HCT.