Cord Blood Transplantation from Unrelated Donors for Children with Acute Lymphoblastic Leukemia in Japan: The Impact of Methotrexate on Clinical Outcomes

Forging international collaboration and alliances to establish the largest transplant center in the north of Vietnam

Through collaboration with international experts, our institution established a highly active and successful hematopoietic stem cell transplant program, providing access to this potentially curative treatment modality for patients with a variety of benign and malignant hematological diseases. The initial development of an autologous stem cell transplant program provided our institution with the infrastructure, equipment, and expertise needed for the subsequent development of an allogeneic stem cell transplant program. Key transplant staff received training from international transplant experts at the NHLBI/NIH, the Mayo Clinic, the Johns Hopkins Hospital, and Nagoya Japan, providing them with the expertise to conduct a variety of different transplant approaches, including PBSC transplants from HLA-matched relatives, unrelated cord blood transplants, haploidentical transplants, and CD34 selected stem cell transplants. Patient characteristics were varied among all groups. The number of allogeneic and autologous transplants performed at the NIHBT has increased steadily every year since the initiation of our transplant program. By 2022, 547 transplant procedures had been performed, including 268 autologous and 279 allogeneic transplants. Allogeneic transplants were performed for both malignant and nonmalignant hematological diseases, with acute leukemia (AL) being the most common indication for allogeneic HCT. The majority of recipients undergoing allogeneic transplantation received G-CSF mobilized PBSC allografts from either HLA identical or haplo-identical relatives, with a smaller percentage of patients receiving a UCB transplant or a PBSC allograft that had been CD34+ selected. Amongst the 279 recipients of an allogeneic transplant, mortality rates within day 100 and beyond day 100 were 12.6% and 26.2% respectively. Overall survival (OS) and event-free survival at 5 years in benign and malignant subgroups were 81% and 73% vs 52% and 48% respectively. Through collaboration with international transplant experts, the National Institute of Hematology and Blood Transfusion in Hanoi has stood up the most active transplant center in the northern region of Vietnam. Patients coming from low-income financial backgrounds are now able to receive a variety of different state-of-the-art transplant approaches that are affordable and have been associated with excellent long-term outcomes.

Total Body Irradiation Versus Chemotherapy Conditioning in Pediatric Acute Lymphoblastic Leukemia Patients Undergoing Hematopoietic Stem Cell Transplant: A Systematic Review and Meta-Analysis

Allogeneic hematopoietic stem cell transplant (HSCT) is indicated in pediatric patients with acute lymphoblastic leukemia (ALL) who have relapsed or are at a very high risk of relapse during first complete remission. Two types of myeloablative conditioning are employed before allogeneic HSCT: total body irradiation (TBI)-based regimens and chemotherapy (CHT) alone. This study compares the efficacy and safety of TBI-based regimens and CHT-based conditioning in pediatric, adolescent, and young adult patients with ALL (0-24 years old). TBI-based and CHT-conditioning regimens were evaluated in 4262 and 1367 patients, respectively, from 15 studies. Compared to CHT alone, TBI-based regimens were associated with better overall survival (OS), relative risk (RR) 1.21, better event-free survival (RR 1.34), and a reduced risk of relapse (RR 0.69). Both approaches had comparable risk of acute graft-versus-host disease (GVHD), grades 3 to 4 acute GVHD, chronic GVHD, and nonrelapse mortality (NRM). In the subgroup analysis for patients in first complete remission, TBI-based regimens and CHT alone had comparable OS and NRM. Our results demonstrate the superiority of TBI-based regimens compared to CHT alone in pediatric patients with ALL.

Hematopoietic Cell Transplantation with Reduced Intensity Conditioning Using Fludarabine/Busulfan or Fludarabine/Melphalan for Primary Immunodeficiency Diseases

PURPOSE

The purpose of our study was to compare the safety and efficacy of hematopoietic cell transplantation (HCT) using fludarabine (Flu)-based reduced intensity conditioning (RIC) with busulfan (BU) or melphalan (Mel) for primary immunodeficiency diseases (PID).

METHODS

We retrospectively analyzed transplant outcome, including engraftment, chimerism, immune reconstitution, and complications in 15 patients with severe combined immunodeficiency (SCID) and 27 patients with non-SCID PID. The patients underwent Flu-based RIC-HCT with BU (FluBU: 7 SCID, 16 non-SCID) or Mel (FluMel: 8 SCID, 11 non-SCID). The targeted low-dose BU with therapeutic drug monitoring was set to 30 mg hour/L for SCID.

RESULTS

The 2-year overall survival of all patients was 79.6% and that of patients with SCID in the FluBU and FluMel groups was 100% and 62.5%, respectively. In the FluBU group, all seven patients achieved engraftment, good immune reconstitution, and long-term survival. All five patients receiving umbilical cord blood transplantation achieved complete or high-level mixed chimerism and sufficient specific IgG production. In the FluMel group, six of eight patients achieved complete or high-level mixed chimerism. Viral reactivation or new viral infection occurred in one FluBU group patient and four FluMel group patients. In the non-SCID group, 10 of 11 patients (91%) who received FluMel achieved complete or high-level mixed chimerism but had variable outcomes. Patients with WAS (2/2 patients), NEMO deficiency (2/2 patients), and X-linked hyper IgM syndrome (2/3 patients) who received FluBU achieved complete or high-level mixed chimerism and long-term survival.

CONCLUSIONS

RIC-HCT with FluBU is a safe and effective strategy for obtaining high-level donor chimerism, immune reconstitution including B cell function, and long-term survival in patients with SCID. In patients with non-SCID PID, the results varied according to the subtype of the disease. Further prospective studies are required to optimize the conditioning regimen for non-SCID PID.

Hematopoietic stem cell transplantation in children and adolescents with nonremission acute lymphoblastic leukemia

BACKGROUND

The appropriateness of allogeneic hematopoietic stem cell transplantation (HSCT) in children and adolescents with leukemia in whom complete remission is not possible remains unclear. This retrospective analysis aimed to investigate the outcomes associated with HSCT, and the risks of HSCT in children and adolescents with nonremission acute lymphoblastic leukemia (ALL).

PROCEDURE

Data from the Japan Society for Hematopoietic Cell Transplantation registry on 325 patients with nonremission ALL (aged <21 years, with blasts in the peripheral blood and/or bone marrow) who had undergone HSCT between January 2001 and December 2015 were evaluated. To assess survival, we developed a scoring system using significant adverse pre-HSCT variables.

RESULTS

Overall, 247 patients died. The median length of follow up among survivors was 1145 days, and the 3-year overall survival was 22% (95% confidence interval [CI]: 18-27%). A low performance score, presence of >25% bone marrow blasts, T-cell phenotype, poor-risk or normal cytogenetics, and history of HSCT were predictors of a poor outcome. Patients scoring 0-1 (n = 109), 2 (n = 91), and 3-7 (n = 125) had a 3-year overall survival of 41% (95% CI: 31-51%), 21% (95% CI: 13-31%), and 7% (95% CI: 3-12%), respectively.

CONCLUSION

These results support HSCT in certain nonremission patients. Even in patients without complete remission, outcomes differed according to pre-HSCT factors. A scoring system could help determine the appropriateness of HSCT in children and adolescents with nonremission ALL.

Unrelated cord blood transplantation with myeloablative conditioning for pediatric acute lymphoblastic leukemia in remission: prognostic factors

The number of individuals undergoing unrelated cord blood transplantation (UCBT) has increased in recent years; however, information on prognostic factors is limited. We retrospectively analyzed data from 475 children and adolescents receiving UCBT with myeloablative conditioning for acute lymphoblastic leukemia (ALL) in complete remission (CR), based on a nationwide registry. In the total patient cohort, 5-year leukemia-free survival (LFS) and overall survival (OS) rates after UCBT were 61.1% and 67.7%, respectively. UCBT at first CR and UCBT after 2007 were associated with good survival, while grade II-IV acute graft-versus-host disease (GVHD) was associated with low relapse rate but did not affect survival. Analysis according to human leukocyte antigen (HLA) disparity revealed that tacrolimus-based GVHD prophylaxis resulted in higher OS and lower relapse rate and nonrelapse mortality (NRM) than cyclosporine-based GVHD prophylaxis in patients transplanted with 6/6 and ≤4/6 HLA-matched umbilical cord blood. Furthermore, grade II-IV acute GVHD was associated with good LFS and low relapse rate, without high NRM, in patients receiving 5/6 HLA-matched UCBT. These data indicate that prognostic factors for ALL differ depending on HLA disparity in UCBT.

Optimizing Preparative Regimen for Umbilical Cord Blood Transplantation in Adult Acute Leukemia Patients: Acute Lymphoblastic Leukemia Requires Myeloablative Conditioning but Not Acute Myeloid Leukemia

Cord blood transplantation (CBT) is a valuable alternative to bone marrow transplantation in adults without readily available donors. We conducted this study to investigate the feasibility of CBT for adult patients with acute leukemia with regards to impact of different conditioning and graft-versus-host disease (GVHD) prophylaxis regimens on clinical outcomes. From 16 centers in Korea, 41 acute myeloid leukemia (AML) and 29 ALL (acute lymphoblastic leukemia) patients undergoing CBT were enrolled. For AML patients, the neutrophil engraftment was observed in 87.5% of reduced intensity conditioning (RIC) and 72.0% of myeloablative conditioning (MAC) (p = 0.242). The median RFS was 5 months and OS 7 months. Conditioning regimen did not affect relapse free survival (RFS) or overall survival (OS). GVHD prophylaxis using calcineurin inhibitors (CNI) plus methotrexate was associated with better RFS compared to CNI plus ATG (p = 0.032). For ALL patients, neutrophil engraftment was observed in 55.6% of RIC and 90.0% of MAC (p = 0.034). The median RFS was 5 months and OS 19 months. MAC regimens, especially total body irradiation (TBI)-based regimen, were associated with both longer RFS and OS compared to other conditioning regimens. In conclusion, individualized conditioning regimens will add value in terms of enhancing safety and efficacy of CBT.

Reduced dose of MTX for GVHD prophylaxis promotes engraftment and decreases non-relapse mortality in umbilical cord blood transplantation

Although a combination of calcineurin inhibitor and methotrexate (MTX) is used for graft-versus-host disease (GVHD) prophylaxis in umbilical cord blood transplantation (CBT), optimal dose of MTX for CBT remains to be determined.We conducted a retrospective study to evaluate the safety and efficacy of standard-dose MTX (St-MTX, 15 mg/m² on day 1 and 10 mg/m² on days 3 and 6) and mini-dose MTX (Mini-MTX, 5 mg/m² on days 1, 3 and 6) for GVHD prophylaxis in patients who underwent single unit CBT against hematological malignancies.Thirty-two and 26 patients received St-MTX and Mini-MTX, respectively. Cumulative incidence of neutrophil engraftment was significantly higher in the Mini-MTX group than in the St-MTX group (88.5% vs 65.6%, P = 0.00448). Cumulative incidences of grade II to IV and grade III to IV of acute graft-versus-host disease (GVHD) were 34.4% and 6.2% in the St-MTX group, and 34.6% and 7.7% in the Mini-MTX group with no statistical significance. One-year non-relapse mortality (NRM) was significantly lower in the Mini-MTX group compared to the St-MTX group (31.2% vs 3.8%, P = 0.00938), whereas relapse rate was not different between the groups. Multivariate analysis also indicated that Mini-MTX significantly improved engraftment (HR, 0.5359; 95% CI, 0.3082 to 0.9318; P = 0.0270) and reduced NRM (HR, 0.117; 95% CI, 0.0151 to 0.9067; P = 0.040).Our study suggests that GVHD prophylaxis using Mini-MTX in CBT is feasible and associated with improvement of engraftment and reduction in NRM.

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.

Graft-versus-host disease (GVHD) prophylaxis by using methotrexate decreases pre-engraftment syndrome and severe acute GVHD, and accelerates engraftment after cord blood transplantation

GVHD and graft failure are serious problems in CBT. PES after CBT also occurs frequently and is associated with transplantation-related complications such as acute GVHD. We reviewed medical records for 70 consecutive child CBT recipients between December 1997 and April 2015. Forty-nine patients received prophylaxis against GVHD with CsA or Tac in combination with mPSL from day +7 (mPSL group), and 21 patients received CsA or Tac with MTX on day +1 and day +3 (MTX group). Neutrophil engraftment was detected in 59 patients (84.3%). Neutrophil engraftment rate in the MTX group was significantly higher than that in the mPSL group (21/21 (100%) and 38/49 (77.6%), respectively, p = 0.027). PES developed in 35 patients, and the incidence of PES in the mPSL group was significantly higher than that in the MTX group (p = 0.036). The incidence of severe acute GVHD (grade III or IV) in the MTX group was significantly lower than that in the mPSL group (p = 0.049). Although this study was a small-scale study, the results showed that increase in the rate of engraftment and decrease in the incidence of early immune reactions such as PES and severe acute GVHD could be achieved by early commencement of immunosuppression using MTX.

Sustained release of methotrexate through liquid-crystalline folate nanoparticles

To make chemotherapy more effective, sustained release of the drug is desirable. By controlling the release rates, constant therapeutic levels can be achieved which can avoid re-administration of drug. This helps to combat tumors more effectively with minimal side effects. The present study reports the control release of methotrexate through liquid-crystalline folate nanoparticles. These nanoparticles are composed of highly ordered folate self-assembly which encapsulate methotrexate molecules. These drug molecules can be released in a controlled manner by disrupting this assembly in the environment of monovalent cations. The ordered structure of folate nanoparticles offers low drug losses of about 4-5%, which is significant in itself. This study reports the size-control method of forming methotrexate encapsulated folate nanoparticles as well as the release of methotrexate through these nanoparticles. It has been demonstrated that methotrexate release rates can be controlled by controlling the size of the nanoparticles, cross-linking cation and cross-linking concentration. The effect of different factors like drug loading, release medium, and pH of the medium on methotrexate release rates was also studied.

Graft-versus-host disease and survival after cord blood transplantation for acute leukemia: a comparison of Japanese versus White populations

An earlier report identified higher risks of acute and chronic graft-versus-host disease (GVHD) in White children compared with the Japanese after HLA-matched sibling transplantations. The current analysis explored whether racial differences are associated with GVHD risks after unrelated umbilical cord blood transplantation. Included are patients of Japanese descent (n = 257) and Whites (n = 260; 168 of 260 received antithymocyte globulin [ATG]). Transplants were performed in the United States or Japan between 2000 and 2009; patients were aged 16 years or younger, had acute leukemia, were in complete remission, and received a myeloablative conditioning regimen. The median ages of the Japanese and Whites who received ATG were younger at 5 years compared with 8 years for Whites who did not receive ATG. In all groups most transplants were mismatched at 1 or 2 HLA loci. Multivariate analysis found no differences in risks of acute GVHD between the Japanese and Whites. However, chronic GVHD was higher in Whites who did not receive ATG compared with the Japanese (hazard ratio, 2.16; P < .001), and treatment-related mortality was higher in Whites who received ATG compared with the Japanese (relative risk, 1.81; P = .01). Nevertheless, there were no significant differences in overall survival between the 3 groups.

Allogeneic hematopoietic cell transplantation for acute lymphoblastic leukemia in adults

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a heterogeneous disease, for which treatment guidelines are still evolving. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapeutic modality for ALL, and this review describes the recent studies and current practice patterns concerning the who, when, and how of allo-HCT in the management of ALL.

RECENT FINDINGS

Allogeneic stem cell transplantation is the treatment of choice for patients with ALL after first relapse and is also recommended for high-risk patients in first complete remission (CR1). Minimal residual disease evaluation and monitoring is developing as an important prognostic factor and could guide physicians in determining which patients, especially those with standard risk, might require transplant. Tyrosine kinase inhibitor (TKI) therapy allows a much higher proportion of Philadelphia-chromosome-positive ALL patients to attain remission and proceed to transplant with improved results; posttransplant TKI maintenance therapy may also provide survival benefit. Reduced-intensity conditioning regimens are a reasonable alternative for patients who would otherwise be ineligible for transplant because of age or comorbidity.

SUMMARY

For patients with high-risk features, there is general agreement that allo-HCT in CR1 is a potentially curative option; however, there is no consensus on early transplant for standard-risk patients.