Comparison of Donor Sources in Hematopoietic Stem Cell Transplantation for Childhood Acute Leukemia: A Nationwide Retrospective Study

Allogeneic Hematopoietic Cell Transplantation With Reduced Toxicity Conditioning for Pediatric B Lymphoid Malignancy

BACKGROUND

Conventional conditioning regimens for children with lymphoid malignancy undergoing allogeneic hematopoietic cell transplantation (HCT) are myeloablative and involve high-dose total body irradiation (TBI). Such regimens are associated with significant late complications.

OBSERVATIONS

Here, we used a reduced-toxicity conditioning regimen comprising fludarabine, cytarabine, melphalan, and low-dose TBI (FLAMEL) to treat 5 patients with lymphoid malignancy before HCT. Four patients maintained complete remission (range, 18 to 63 mo), whereas the remaining patient who had positive minimal residual disease (MRD) before HCT relapsed.

CONCLUSIONS

FLAMEL might be a suitable conditioning regimen for children with lymphoid malignancy if pre-HCT MRD is negative.

Unrelated cord blood transplantation vs. HLA-matched sibling transplantation for adults with B-cell acute lymphoblastic leukemia in complete remission: superior OS for patients with long-term survival

Background

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an important curative therapy for adult acute lymphoblastic leukemia (ALL). For patients who lack a human leukocyte antigen (HLA)-matched sibling donor, unrelated cord blood (UCB) is an alternative graft option. Previous studies have focused mainly on all T- and B-cell ALL (B-ALL) patients, while data related specifically to adult B-ALL patients after UCB transplantation (UCBT) are scarce.

Methods

We retrospectively compared the outcomes of UCBT and HLA-matched sibling transplantation (MST) in the treatment of adult B-ALL patients in complete remission (CR) at our center. From June 2006 to December 2020, 156 adult B-ALL patients who achieved CR before transplantation were enrolled. The main clinical outcomes of UCBT and MST were analyzed.

Results

Hematopoietic recovery was significantly faster in MST recipients than in UCBT recipients. Higher incidences of grades II-IV and III-IV acute graft-versus host disease (aGVHD) were found in UCBT recipients (P < 0.001 and = 0.03), while a lower incidence of extensive chronic GVHD (cGVHD) was found in UCBT recipients (P < 0.001). The cumulative incidences of 2-year non-relapse mortality (NRM), 2-year relapse, 5-year disease-free survival (DFS) and 5-year GVHD-free relapse-free survival (GRFS) were comparable between MST and UCBT recipients. The overall survival (OS) during the first 700 days was similar between the MST and UCBT groups, while the OS of patients with a survival time of more than 700 days in the UCBT group was better than that in the MST group according to multivariate analysis (P = 0.03).

Conclusions

Our study shows that when treating adult B-ALL patients in CR, UCBT can achieve comparable effects as MST, may provide superior OS for patients with long-term survival, and should be considered a good alternative.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03186-3.

Impact of human leukocyte antigen mismatch on outcomes after unrelated bone marrow transplantation in paediatric patients: A retrospective analysis by the JSTCT HLA working group

The impact of human leukocyte antigen (HLA) mismatching at the HLA-A, -B, -C, and -DRB1 loci after unrelated bone marrow transplantation in paediatric patients with haematological malignancies has not been fully examined. Here, we analysed patients with haematological malignancies (all aged ≤15 years; n = 1330) who underwent a first unrelated bone marrow transplantation between 1993 and 2017 in Japan. The results show that although an HLA mismatch was significantly associated with a low relapse rate, it was also associated with higher non-relapse mortality. There was a significant association between HLA mismatch and low overall survival. Locus mismatch analysis revealed that, as in adults, an HLA-C mismatch had a significant negative impact on survival; however, in paediatric patients, an HLA-DRB1 mismatch did not have a negative impact, although these HLA mismatch effects are weakened in recent cases. Taken together, the results suggest that an HLA-matched donor should be the first candidate for paediatric patients; however, for patients without a matched sibling or matched unrelated donor, we can select an unrelated donor with a mismatch at HLA-DRB1 if available.

Title: Prognostic factors of children and adolescents with T-cell acute lymphoblastic leukemia after allogeneic transplantation

Acute lymphoblastic leukemia (ALL) is the most common cancer during childhood, and some high-risk patients with ALL require hematopoietic stem cell transplantation (HSCT). Mainly due to small patient numbers, studies focusing specifically on children and adolescents with T-cell ALL (T-ALL) are limited. Using a nationwide registry, we retrospectively analyzed data from patients under 20 years old who underwent their first HSCT for T-ALL between 2000 and 2018. As a result, total 484 patients were included, and their median follow-up period was 6.9 years after HSCT for survivors. While patients receiving HSCT at first complete remission (CR) showed relatively good 5-year leukemia free survival (5yLFS, 73.5%), once relapse occurred, their prognosis was much worse (44.4%) even if they attained second remission again (p < 0.001). Among patients receiving HSCT at CR1, grade II-IV acute graft versus host disease was associated with worse overall and LFS than grade 0-I (5yLFS 69.5% vs 82.1%, p = 0.026) mainly due to high non-relapse mortality. Among those patients, patients receiving related bone marrow transplantation, unrelated bone marrow transplantation, or unrelated cord blood transplantation showed similar survival (5yLFS, 73.2%, 76.3%, and 77.0%, respectively). For patients undergoing cord blood transplantation at CR1, total-body irradiation-based myeloablative conditioning was associated with better 5yLFS than other conditioning regimens (85.4% vs 62.2%, p = 0.044), as it reduced the risk of relapse. These results indicate that relapsed patients have much less chance of cure, and that identifying patients who require HSCT for cure and offering them HSCT with optimal settings during CR1 are crucial for children and adolescents with T-ALL. This article is protected by copyright. All rights reserved.

Encouraging Outcomes of Alternate Donor Hematopoietic Stem Cell Transplant in Pediatric High-risk/Relapsed Leukemias: A Single Center Experience

Outcomes of high-risk and relapsed pediatric acute leukemias continue to be suboptimal. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative modality. However, <30% of patients have matched sibling donors available. Hence, alternate donors (matched unrelated and haploidentical) are being used to improve outcomes. We retrospectively analyzed our data of all children with high-risk/relapsed acute leukemias who underwent alternate donor HSCT at our center from April 2015 to July 2020. A total of 15 patients were included-3 underwent matched unrelated and 12 underwent haploidentical HSCT. Before HSCT, all patients were in complete remission (CR): CR1-1, CR2-11, and CR3-3. All patients engrafted except one. Median time to neutrophil and platelet engraftment was 15 and 16 days, respectively. There were 3 transplant related mortalities. One patient was lost to follow-up. Remaining 11 patients remain in remission and are alive. The cumulative incidence of acute graft versus host disease was 57.1% and of chronic graft versus host disease was 21.4%. Overall survival was 80% and the event-free survival was 73.3%. The median follow-up of alive patients was 775 days (range: 333 to 2077 d). Our experience shows encouraging outcomes using alternate donor HSCT for these patients from developing world.

Prednisolone poor response is not an indication for HSCT in pediatric B-cell precursor acute lymphoblastic leukemia in first remission: results from JACLS ALL-02 study

Approximately 90% of pediatric acute lymphoblastic leukemia (ALL) cases are curable with intensified chemotherapy, but very high-risk patients may require hematopoietic stem cell transplantation (HSCT). A suitable indication for HSCT in the first complete remission (CR1) should be defined to protect patients from long-term complications. We report the outcomes of HSCT in CR1 from the Japan Association of Childhood Leukemia Study (JACLS) ALL-02 study and reassess indications for HSCT. Of 1114 patients, 71 (6.4%) received HSCT in CR1. Indications included high-risk cytogenetic abnormalities and non-CR on day 33. Patients with B-cell precursor (BCP) ALL and a prednisolone poor response (PPR) received HSCT when leukocyte antigen-matched siblings were available. The 4-year overall survival (OS) of transplanted patients was 78.8% (confidence interval 67.3-86.6). Multivariate analysis revealed that cord blood transplantation was associated with poor OS. For BCP-ALL patients with PPR who achieved CR1 after induction therapy, HSCT in CR1 showed excellent outcomes (4-year OS 90.9%) but demonstrated no survival advantage as the outcome with chemotherapy was also excellent (4-year OS 97.0%). This study suggests that in BCP-ALL patients PPR is not an indication for HSCT in CR1. Precise evaluation of treatment responses would increase sophistication of indications for HSCT in CR1.

Alternative donor peripheral blood stem cell transplantation for the treatment of high-risk refractory and/or relapsed childhood acute leukemia: a randomized trial

Background

The high-risk refractory and/or relapsed (R/R) childhood acute leukemia prognosis is poor, and allogeneic stem cell transplantation (allo-HSCT) is the most prudent treatment modality. However, there are limited matched sibling donors (MSDs), and alternative donors (ADs) are the main source for allo-HSCT. Thus, we evaluated the clinical efficacy of AD peripheral allo-HSCT for treating high-risk R/R childhood acute leukemia.

Methods

We assessed 111 children who underwent allo-HSCT at the Affiliated Cancer Hospital of Zhengzhou University between October 2006 and July 2019. The patients were divided in the MSD and AD groups, and their clinical characteristics, complications, and survival rates were compared.

Results

The cumulative incidences of Epstein–Barr virus and cytomegalovirus infections were significantly higher in the AD than in the MSD group (P < 0.001); however, the recurrence and mortality rates were significantly higher in the MSD than in the AD group (P < 0.05). Furthermore, the 5-year disease-free (DFS) (65.2% vs. 43.3%, P = 0.033) and overall survival (OS) rates (71.6% vs. 53.8%, P = 0.053) were significantly higher in the AD than in the MSD group. In the AD group, the grade II–IV acute graft-versus-host disease (aGVHD), donor-recipient ABO compatibility, conditioning regimen, and CMV infection affected the 5-year OS. The grade II–IV aGVHD also affected the 5-year DFS; however, only the donor-recipient ABO compatibility affected the 5-year DFS. The donor MSD (HR: 2.035, 95% confidence interval [CI] 1.057–3.920, P = 0.034) and the grade II–IV aGVHD (HR: 2.914, 95% CI 1.261–6.736, P = 0.012) affected the 5-year DFS of childhood acute leukemia after allo-HSCT, and the grade II–IV aGVHD (HR: 3.016, 95% CI 1.217–7.473, P = 0.017) affected the 5-year OS. Moreover, the donor source (HR: 2.836, 95% CI 1.179–6.823, P = 0.020) and grade II–IV aGVHD (HR: 3.731, 95% CI 1.332–10.454, P = 0.012) were independent predictors of the 5-year DFS, while the latter (HR: 3.524, 95% CI 1.310–10.988, P = 0.030) was an independent predictor of the 5-year OS.

Conclusions

AD-PBSCT was effective for high-risk R/R childhood leukemia and may have better clinical outcomes than MSD-PBSCT; thus, it can be used as first-line treatment for high-risk R/R childhood leukemia.

Partially CD3+-Depleted Unrelated and Haploidentical Donor Peripheral Stem Cell Transplantation Has Favorable Graft-versus-Host Disease and Survival Rates in Pediatric Hematologic Malignancy

Most children who may benefit from stem cell transplantation lack a matched related donor. Alternative donor transplantations with an unrelated donor (URD) or a partially matched related donor (PMRD) carry an increased risk of graft-versus-host-disease (GVHD) and mortality compared with matched related donor transplantations. We hypothesized that a strategy of partial CD3⁺/CD19⁺ depletion for URD or PMRD peripheral stem cell transplantation (PSCT) would attenuate the risks of GVHD and mortality. We enrolled 84 pediatric patients with hematologic malignancies at the Children's Hospital of Philadelphia and the Children's Hospital of Wisconsin between April 2005 and February 2015. Two patients (2.4%) experienced primary graft failure. Relapse occurred in 23 patients (27.4%; cumulative incidence 26.3%), and 17 patients (20.2%) experienced nonrelapse mortality (NRM). Grade III-IV acute GVHD was observed in 18 patients (21.4%), and chronic GVHD was observed and graded as limited in 24 patients (35.3%) and extensive in 8 (11.7%). Three-year overall survival (OS) was 61.8% (95% confidence interval [CI], 50.2% to 71.4%) and event-free survival (EFS) was 52.0% (95% CI, 40.3% to 62.4%). Age ≥15 years was associated with decreased OS (P= .05) and EFS (P= .05). Relapse was more common in children in second complete remission (P = .03). Partially CD3⁺-depleted alternative donor PSCT NRM, OS, and EFS compare favorably with previously published studies of T cell-replete PSCT. Historically, T cell-replete PSCT has been associated with a higher incidence of extensive chronic GVHD compared with limited chronic GVHD, which may explain the comparatively low relapse and NRM rates in our study cohort despite similar overall rates of chronic GVHD. Partial T cell depletion may expand donor options for children with malignant transplantation indications lacking a matched related donor by mitigating, but not eliminating, chronic GVHD.

Current status of umbilical cord blood transplantation in children

The first umbilical cord blood (UCB) transplantation was performed 30 years ago. UCB transplantation (UCBT) is now widely used in children with malignant and non-malignant disorders who lack a matched family donor. UCBT affords a lower incidence of graft-versus-host disease compared to alternative stem cell sources, but also presents a slower immune recovery and a high risk of infections if serotherapy is not omitted or targeted within the conditioning regimen. The selection of UCB units with high cell content and good human leucocyte antigen match is essential to improve the outcome. Techniques, such as double UCBT, ex vivo stem cell expansion and intra-bone injection of UCB, have improved cord blood engraftment, but clinical benefit remains to be demonstrated. Cell therapies derived from UCB are under evaluation as potential novel strategies to reduce relapse and viral infections following transplantation. In recent years, improvements within haploidentical transplantation have reduced the overall use of UCBT as an alternative stem cell source; however, each may have its relative merits and disadvantages and tailored use of these alternative stem cell sources may be the optimal approach.

Factors Associated with Long-Term Risk of Relapse after Unrelated Cord Blood Transplantation in Children with Acute Lymphoblastic Leukemia in Remission

For pediatric patients with acute lymphoblastic leukemia (ALL), relapse is an important cause of treatment failure after unrelated cord blood transplant (UCBT). Compared with other donor sources, relapse is similar or even reduced after UCBT despite less graft-versus-host disease (GVHD). We performed a retrospective analysis to identify risk factors associated with the 5-year cumulative incidence of relapse after UCBT. In this retrospective, registry-based study, we examined the outcomes of 640 children (<18 years) with ALL in first complete remission (CR1; n = 257, 40%) or second complete remission (CR2; n = 383, 60%) who received myeloablative conditioning followed by a single-unit UCBT from 2000 to 2012. Most received antithymocyte globulin (88%) or total body irradiation (TBI; 69%), and cord blood grafts were primarily mismatched at 1 (50%) or 2+ (34%) HLA loci. Considering patients in CR1, the rates of 5-year overall survival (OS), leukemia-free survival (LFS), and relapse were 59%, 52%, and 23%, respectively. In multivariate analysis (MVA), acute GVHD (grades II to IV) and TBI protected against relapse. In patients in CR2, rates of 5-year OS, LFS, and the cumulative incidence of relapse were 46%, 44%, and 28%, respectively. In MVA, longer duration from diagnosis to UCBT (≥30 months) and TBI were associated with decreased relapse risk. Importantly, receiving a fully HLA matched graft was a strong risk factor for increased relapse in MVA. An exploratory analysis of all 640 patients supported the important association between the presence of acute GVHD and less relapse but also demonstrated an increased risk of nonrelapse mortality. In conclusion, the impact of GVHD as a graft-versus-leukemia marker is evident in pediatric ALL after UCBT. Strategies that promote graft-versus-leukemia while harnessing GVHD should be further investigated.