Improved prognosis with additional medium-dose VP16 to CY/TBI in allogeneic transplantation for high risk ALL in adults

Intensified conditioning regimens with total marrow irradiation/etoposide/cyclophosphamide and busulfan/etoposide/cyclophosphamide overcome the impact of pre-transplant minimal residual disease on outcomes in high-risk acute lymphoblastic leukemia patients in complete remission

PURPOSE

Among high-risk acute lymphoblastic leukemia (ALL) patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), those with positive minimal residual disease (MRD) are susceptible to poor outcomes. Therefore, it is necessary to determine the most suitable preparatory regimen for these patients.

METHODS

Data were analyzed from 141 patients who received allo-HSCT and were diagnosed with high-risk ALL. These patients underwent intensified conditioning regimens, including either total marrow and lymphoid irradiation (TMLI)-etoposide (VP16)-cyclophosphamide (CY) or busulfan (BU)-VP16-CY between October 2016 and November 2022. A total of 141 individuals were in complete remission (CR) before transplantation and, among all patients, 90 individuals exhibited a negative MRD status and 51 patients had a positive MRD status.

RESULTS

In patients who tested negative for MRD, the incidence of relapse within a 2-year timeframe was 25.0% (24.8%-25.5%), compared with 32.2% (31.2%-33.2%) in MRD-positive patients; however, this difference was not statistically significant. There were no significant differences in the 2-year disease-free survival (DFS) and 2-year overall survival (OS) rates between the MRD-negative and MRD-positive groups (DFS: 67.2% (57.9%-78.1%) vs. 55.5% (42.6%-72.3%); OS: 69.0% (61.9%-88.2%) vs. 66.7% (53.9%-82.5%)). Furthermore, no notable variations were observed in the occurrence of transplant-related mortality (TRM) and graft-versus-host disease (GVHD) across the two groups.

CONCLUSION

This study reveals the benefits of TMLI-VP16-CY and BU-VP16-CY conditioning regimens in high-risk ALL patients with CR and MRD-positive status. A large-scale prospective clinical trial is warranted in the future.

Pre-transplant phase angle as a potential marker for predicting the development of infection after allogeneic hematopoietic stem cell transplantation

BACKGROUND & AIMS

Nutritional assessment in allogeneic hematopoietic stem cell transplantation (allo-HSCT) is important and decreased skeletal muscle mass is a risk factor for the development of infection. Recently, it has become clear that qualitative rather than skeletal muscle mass loss is a marker that reflects post-transplant outcome, but its association with the development of infection remains unclear. Therefore, we assessed skeletal muscle status by body composition using bioelectrical impedance analysis (BIA) and investigated its association with the development of infection.

METHODS

A retrospective cohort study was conducted to assess the quantity as well as quality of skeletal muscle using the body composition of BIA assessment. The quantitative (appendicular skeletal muscle mass index; ASM) and qualitative (phase angle; PhA) indicators of skeletal muscle calculated from body composition analysis were used to determine factors influencing the development of infection after allo-HSCT.

RESULTS

In total, 80 adult patients, aged 20-70 years (median, 52) were included in this study. The ASM was mildly decreased after allo-HSCT and PhA was significantly decreased. Furthermore, low pre-transplant PhA was identified as an independent risk factor for the development of infection early after transplantation, with a cutoff value of 4.9°.

CONCLUSION

In particular, pre-transplant PhA may predict the development of infection early after allo-HSCT, and muscle indices that can be assessed with pre-transplant body composition are a useful evaluation method that can discriminate post-transplant outcomes.

Medium-dose etoposide, cyclophosphamide and total body irradiation conditioning potentiates anti-leukemia immunity in adults with acute lymphoblastic leukemia without aggravating graft-versus-host disease

Medium-dose etoposide (ETP), cyclophosphamide (CY) and total body irradiation (TBI) is a beneficial conditioning regimen for allogeneic hematopoietic cell transplantation (allo-HCT) in adults with acute lymphoblastic leukemia (ALL), especially with high-risk ALL, as compared with CY and TBI conditioning. ETP may enhance immunogenicity of leukemia-associated antigens through increased expression of major histocompatibility antigen complex class I, leading to cross-priming of T cells by dendritic cells and generating leukemia-specific cytotoxic T cells. Furthermore, ETP can eliminate activated effector T cells, sparing naïve and memory T cells, accompanied with depletion of regulatory T cells. These mechanisms are supposed to lead to inhibit immune escape of leukemia cells and enhance anti-leukemia immunity in addition to direct cytotoxicity of ETP, followed by an efficient eradication of leukemia cells. According to the findings of pharmacokinetics studies, spreading the administration of low-dose ETP may be more efficacious than non-spreading administration, to induce a potent anti-leukemia immunity without aggravating graft-versus-host disease and transplant-related toxicity. In the present review, I discuss the immunological aspects elicited by the addition of medium-dose ETP to the CY/TBI conditioning and the possible positioning of allo-HCT with this conditioning in adults with ALL, considering recent progress in non-HCT treatment including bispecific antibody-based therapy.

Total marrow lymphoid irradiation and cyclophosphamide is associated with low toxicity and good outcomes in patients undergoing hematopoietic stem cell transplantation for acute lymphoblastic leukemia and chronic myeloid leukemia in lymphoid blast crises - A phase I study

INTRODUCTION

Total marrow lymphoid irradiation (TMLI) can deliver higher doses of irradiation without increasing toxicity compared to Total body irradiation (TBI).

METHODS

Twenty adult patients undergoing hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia with lymphoid blast crises (CML-LBC) received TMLI and cyclophosphamide for conditioning. Ten patients each received 13.5 or 15 Gy of TMLI. The graft source was peripheral blood stem cells in all, and donors included matched related (n = 15), haplo-identical (n = 3) or matched unrelated donors (n = 2).

RESULTS

The median cell dose infused was 9 × 106 CD34/kg (range 4.8-12.4). Engraftment occurred in all (100%) at a median of 15 days (range: 14-17). Toxicity was low with hemorrhagic cystitis seen in two but no sinusoidal obstruction syndrome. Acute GVHD occurred in 40% while chronic GVHD was seen in 70.5%. Viral infections were seen in 55% while blood stream bacterial infections occurred in 20% and invasive fungal disease (IFD) in 10%. The Day 100 non-relapse mortality (NRM) was 10%. At a median follow up of 25 months (range 2-48), two patients have relapsed. Overall survival at 2 years is 80% while the disease-free survival is 75%.

CONCLUSIONS

The combination of TMLI and cyclophosphamide for myeloablative conditioning is associated with low toxicity and favorable early outcomes in patients undergoing HSCT for ALL and CML-LBC.

Prognostic impact of complex and/or monosomal karyotypes in post-transplant poor cytogenetic acute myeloid leukaemia: A quantitative approach

To evaluate the prognostic impact of complex karyotype (CK) and/or monosomal karyotype (MK) in combination with various clinical factors on allogeneic stem cell transplantation (HSCT) outcomes of patients with acute myeloid leukaemia (AML), we analysed the registry database of adult AML patients who underwent allogeneic HSCT between 2000 and 2019 in Japan. Among 16 094 patients, those with poor cytogenetic risk (N = 3345) showed poor overall survival (OS) after HSCT (25.3% at 5 years). Multivariate analyses revealed that CK and/or MK (hazard ratio [HR], 1.31 for CK without MK; 1.27 for MK without CK; and 1.73 for both), age at HSCT ≥50 years (HR, 1.58), male sex (HR, 1.40), performance status ≥2 (HR, 1.89), HCT-CI score ≥3 (HR, 1.23), non-remission status at HSCT (HR, 2.49), and time from diagnosis to HSCT ≥3 months (HR, 1.24) independently reduced post-HSCT OS among patients with poor cytogenetic risk AML. A risk scoring system based on the multivariate analysis successfully stratified patients into five distinct groups for OS. This study confirms the negative effects of CK and MK on post-HSCT outcomes, and offers a powerful risk scoring system for predicting prognoses after HSCT among AML patients with unfavourable cytogenetics.

Intensified conditioning regimens improved disease-free survival and engraftment after unrelated single-unit cord blood transplantation but not after matched sibling or matched unrelated donor allogeneic hematopoietic cell transplantation

The impact of conditioning intensity on different donor groups has been unclear in allogeneic transplantation. The objective of this study was to clarify the effect of conditioning intensity on disease-free survival (DFS), relapse, non-relapse mortality (NRM), neutrophil engraftment, and graft-versus-host disease for each donor type. We retrospectively evaluated the effect of conditioning intensity on transplant outcomes for patients with acute leukemia or myelodysplastic syndrome aged between 16 and 60 years in Japan using the transplant conditioning intensity (TCI) scoring system. A total of 8526 patients who received first allogeneic transplantation from 6/6 antigen-matched sibling donor (MSD, n = 2768), 8/8 allele-matched unrelated donor (MUD, n = 2357), and unrelated single-cord blood (UCB, n = 3401) were eligible for the analyses. Compared to conditioning with TCI score 4.0, which was corresponds to conventional myeloablative conditioning, including cyclophosphamide with total body irradiation 12 Gy or busulfan 12.8 mg, and was considered as the reference group in the multivariate analyses, intensified conditioning with TCI score ≥4.5 improved DFS (hazard ratio [HR],0.81, P < 0.001) and relapse rate (HR, 0.70, P < 0.001) but only after UCB transplants and not MSD and MUD transplants. In contrast, NRM was higher after intensified conditioning with TCI score ≥4.5 for MSD (HR, 1.39, P = 0.008) and MUD (HR, 1.47, P = 0.002) transplants but not UCB transplants (HR, 1.12, P = 0.240). Neutrophil engraftment was also significantly higher after intensified conditioning with TCI score ≥4.5 but only for UCB transplants (HR, 1.24, P < 0.001), whereas it was significantly lower after reduced-intensity conditioning with TCI score ≤3.5 for MSD transplants only (HR, 0.82, P < 0.001). These data demonstrated that an intensified conditioning regimen improved survival and engraftment rate only after a UCB transplants. Therefore, TCI scoring system could enable the optimization of conditioning intensity according to donor type, particularly in terms of survival and engraftment.

Belt Electrode-Skeletal Muscle Electrical Stimulation During Early Hematopoietic Post-Transplantation To Prevent Skeletal Muscle Atrophy and Weakness

A decline in physical functions at the early stage of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a serious issue. Belt electrode-skeletal muscle electrical stimulation (B-SES) can induce significant muscle contractions with electrical stimulation and reduce muscle weakness. However, this approach has not been used in allo-HSCT patients. This study aimed to examine the effect of B-SES on physical function, and safety in patients during the early post-transplantation period. Forty-three adult patients who underwent B-SES after allo-HSCT were stratified into 2 groups based on the intensity of electrical stimulation (high versus low). B-SES was performed in combination with exercise therapy for 4 post-transplantation weeks. Knee extensor strength (KES) in the low B-SES group decreased significantly, whereas no change was observed in the high-intervention group. A significant positive correlation was observed between total intensity and ΔKES. A reduction in the 6-minute walking distance in the high B-SES group patients was lower than that of historical data. Two patients had B-SES-related complications including muscle pain. This study is the first to propose a new rehabilitation intervention strategy for allo-HSCT. Combined use of B-SES may be a new approach to reducing the decline of physical function in the early post-transplantation period.

Adult patients with Ph+ ALL benefit from conditioning regimen of medium-dose VP16 plus CY/TBI

The medium-dose etoposide (VP16) added on cyclophosphamide (CY)/total body irradiation (TBI) is one of the intensified myeloablative conditioning regimens used in allogenic hematopoietic stem cell transplantation (allo-HSCT) for acute lymphoblastic leukemia (ALL). However, the patient subgroups who can actually benefit from VP16/CY/TBI compared to CY/TBI have not been precisely defined. Therefore, we conducted a multi-center retrospective study using the Japanese nationwide registry database to elucidate the efficacy of VP16/CY/TBI on post-transplant prognosis. Biological and clinical distinct subtypes (i.e., Philadelphia chromosome-positive (Ph+) and -negative (Ph-) ALL) were evaluated separately, which included 820 Ph+ and 1463 patients with Ph- ALL, respectively. Compared with the CY/TBI group, the VP16/CY/TBI group showed superior progression-free survival (PFS) in patients with Ph+ ALL (65% vs. 57% at 3 years after HSCT; adjusted hazard ratio (HR), 0.73; 95% confidence interval (CI), 0.55-0.98; p = 0.03), along with significantly reduced incidence of relapse (adjusted HR, 0.58; 95% CI, 0.37-0.90; p = 0.02) without the increase of non-relapse mortality (NRM). By contrast, in patients with Ph- ALL, VP16/CY/TBI did not improve PFS nor incidence of relapse; addition of VP16 reduced relapse (HR, 0.65; p = 0.06) in patients with Ph- ALL transplanted at CR1, while improved PFS was not observed (HR, 0.90; p = 0.52) due to increased NRM. This study demonstrated that VP16/CY/TBI is a more effective and well-tolerated regimen in comparison with CY/TBI in patients with myeloablative allo-HSCT for adult Ph+ ALL. Our findings can provide a novel algorithm for conditioning regimen selection in patients with adult ALL.

Outcomes of allogeneic haematopoietic stem cell transplantation with intensity-modulated total body irradiation by helical tomotherapy: a 2-year prospective follow-up study

BACKGROUND AND OBJECTIVES

Intensity-modulated radiation therapy (IMRT) helps achieve good radiation dose conformity and precise dose evaluation. We conducted a single-centre prospective study to assess the safety and feasibility of total body irradiation with IMRT (IMRT-TBI) using helical tomotherapy in allogeneic haematopoietic stem cell transplantation (allo-HSCT).

PATIENTS AND METHODS

Thirty-nine adult patients with haematological malignancy (acute lymphoblastic leukaemia [n = 21], chronic myeloid leukaemia [n = 6], mixed phenotype acute leukaemia [n = 5], acute myeloid leukaemia [n = 4], and malignant lymphoma [n = 3]) who received 12 Gy IMRT-TBI were enrolled with a median follow-up of 934.5 (range, 617-1254) d. At the time of transplantation, 33 patients (85%) achieved complete remission. The conditioning regimen used IMRT-TBI (12 Gy in 6 fractions twice daily, for 3 d) and cyclophosphamide (60 mg/kg/d, for 2 d), seven patients were combined with cytarabine, and five with etoposide. We set dose constraints for the lungs, kidneys and lens as the organs at risk.

RESULTS

The mean doses for the lungs and kidneys were 7.50 and 9.11 Gy, respectively. The mean maximum dose for the lens (right/left) was 5.75/5.87 Gy. The 2-year overall survival (OS), disease-free survival (DFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were 69, 64, 18 and 18%, respectively. Thirty-six patients developed early adverse events (AEs) (including four patients with Grade 3/4 toxicities), most of which were reversible oral mucositis and may partially have been related to IMRT-TBI. However, the incidence of toxicity was comparable to conventional TBI-based conditioning transplantation. None of the patients developed primary graft failure, or Grade III-IV acute graft-versus-host disease (GVHD). In late complications, chronic kidney disease was observed in six patients, a lower incidence compared to conventional TBI-based conditioning transplantation. No radiation pneumonitis or cataracts were observed in any of the patients.

CONCLUSIONS

IMRT-TBI is safe and feasible for haematological malignancies with acceptable clinical outcomes.KEY MESSAGESIMRT-TBI-helical tomotherapy aids in accurate dose calculation and conformity.It could be used without any considerable increase in the rate of TBI-related AEs.Allo-HSCT with IMRT-TBI may be an alternative to conventional TBI for clinical use.

Randomised controlled trial of conditioning regimen for cord blood transplantation for adult myeloid malignancies comparing high-dose cytarabine/cyclophosphamide/total body irradiation with versus without G-CSF priming: G-CONCORD study protocol

INTRODUCTION

A better long-term quality of life after umbilical cord blood transplantation (CBT) is observed compared with transplants from other alternative donors, whereas graft failure and relapses after CBT are still major issues. To minimise graft failure and relapse after CBT, intensification of conditioning by the addition of high-dose cytosine arabinoside (CA) and concomitant continuous use of granulocyte-colony stimulating factor (G-CSF) are reported to convey a significantly better survival after CBT in some retrospective studies. To confirm the effect of G-CSF plus CA combination, in addition to the standard conditioning regimen, cyclophosphamide (CY)/total body irradiation (TBI), we design a randomised controlled study comparing CA/CY/TBI with versus without G-CSF priming (G-CSF combined conditioned cord blood transplantation [G-CONCORD] study).

METHODS AND ANALYSIS

This is a multicentre, open-label, randomised phase III study that aimed to compare G-CSF+CA/CY/TBI as a conditioning regimen for CBT with CA/CY/TBI. Patients with acute myeloid leukaemia or myelodysplastic syndrome, aged 16-55 years, are eligible. The target sample size is 160 and the registration period is 4 years. The primary endpoint is the 2-year disease-free survival rate after CBT. The secondary endpoints are overall survival, relapse, non-relapse mortality, acute and chronic graft-versus-host disease, engraftment rate, time to neutrophil recovery, short-term adverse events, incidence of infections and causes of death.This study employs a single one-to-one web-based randomisation between the with-G-CSF versus without-G-CSF groups after patient registration. Combination of high-dose CA and CY/TBI in both groups is used for conditioning.

ETHICS AND DISSEMINATION

The study protocol was approved by the central review board, Nagoya University Certified Review Board, after the enforcement of the Clinical Trials Act in Japan. The manuscripts presenting data from this study will be submitted for publication in quality peer-reviewed medical journals. Study findings will be disseminated via presentations at national/international conferences and peer-reviewed journals.

TRIAL REGISTRATION NUMBERS

UMIN000029947 and jRCTs041180059.

Safety of total body irradiation using intensity-modulated radiation therapy by helical tomotherapy in allogeneic hematopoietic stem cell transplantation: a prospective pilot study

Total body irradiation using intensity-modulated radiation therapy total body irradiation (IMRT-TBI) by helical tomotherapy in allogeneic hematopoietic stem cell transplantation (allo-HSCT) allows for precise evaluation and adjustment of radiation dosage. We conducted a single-center pilot study to evaluate the safety of IMRT-TBI for allo-HSCT recipients. Patients with hematological malignancies in remission who were scheduled for allo-HSCT with TBI-based myeloablative conditioning were eligible. The primary endpoint was the incidence of adverse events (AEs). Secondary endpoints were engraftment rate, overall survival, relapse rate, non-relapse mortality, and the incidence of acute and chronic graft-versus-host disease (aGVHD and cGVHD, respectively). Between July 2018 and November 2018, ten patients were recruited with a median observation duration of 571 days after allo-HSCT (range, 496-614). D80% for planning target volume (PTV) in all patients was 12.01 Gy. Average D80% values for lungs, kidneys and lenses (right/left) were 7.50, 9.03 and 4.41/4.03 Gy, respectively. Any early AEs (within 100 days of allo-HSCT) were reported in all patients. Eight patients experienced oral mucositis and gastrointestinal symptoms. One patient experienced Bearman criteria grade 3 regimen-related toxicity (kidney and liver). All cases achieved neutrophil engraftment. There was no grade III-IV aGVHD or late AE. One patient died of sinusoidal obstruction syndrome 67 days after allo-HSCT. The remaining nine patients were alive and disease-free at final follow-up. Thus, IMRT-TBI was well tolerated in terms of early AEs in adult patients who underwent allo-HSCT; this warrants further study with longer observation times to monitor late AEs and efficacy.

Oral verruciform xanthoma in chronic graft-versus-host disease patients

BACKGROUND

Verruciform xanthoma (VX) is an uncommon benign epithelial lesion which mainly appears in inflamed oral epithelium. In this study, our aim was to present new cases of oral VX (OVX) in chronic graft-versus-host disease (cGVHD) and review the literature.

METHODS

We conducted a retrospective chart review of cGVHD patients (2012-2019) to reveal cases of OVX. The demographics, medical background, clinical presentation, treatment provided, and follow-up were obtained. Additionally, Medline was searched using the terms "graft-versus-host disease," "verruciform xanthoma," and "oral." Of the articles, the above-mentioned demographic and clinical features were retrieved.

RESULTS

The patient pool included 133 oral cGVHD patients. Three cGVHD patients (males, aged 15-49 years, post-hematologic malignancy) were diagnosed with OVX. All patients had oral mucosal lichenoid lesions, but not in close proximity to the VX lesion. Medline searches revealed 9 cases of OVX in cGVHD patients reported in the literature. Eleven of the 12 patients had oral mucosal lichenoid lesions. Four patients had multiple OVX lesions. All lesions were asymptomatic. Six patients had lesions in the masticatory mucosa (hard palate and gingiva) and 4 patients had lesions in the buccal mucosa.

CONCLUSIONS

To the best of our knowledge, this is the largest published OVX in cGVHD series, including 12 patients. It appears that despite the higher prevalence in cGVHD patients relative to the general population, OVXs do not necessarily develop in sites with lichenoid lesions. It is advised that clinicians be familiar with the clinical and histological features in order to consider OVX in the differential diagnosis of oral lesions in cGVHD patients.

Reduced-intensity conditioning is a reasonable alternative for Philadelphia chromosome-positive acute lymphoblastic leukemia among elderly patients who have achieved negative minimal residual disease: a report from the Adult Acute Lymphoblastic Leukemia Working Group of the JSHCT

Reduced-intensity conditioning (RIC) regimens have been widely used for allogeneic hematopoietic cell transplantation (HCT) in elderly patients. After the emergence of tyrosine kinase inhibitor (TKI), most patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL) now achieve negative results for minimal residual disease (MRD) at HCT. In this study, we evaluated patients aged 50 years or more with Ph-positive ALL who received TKI before HCT, achieved negative-MRD at HCT, and underwent their first allogeneic HCT between 2008 and 2017. In total, 90 and 136 patients who received myeloablative conditioning (MAC) and a RIC regimen, respectively, were included. The median age of patients with MAC and RIC was 54 and 60 years, respectively. Even in multivariate analyses, RIC was not significantly associated with overall mortality (hazard ratio [HR], 1.09; P = 0.724), hematological relapse (HR, 1.97; P = 0.170), or non-relapse mortality (HR, 0.84; P = 0.540). Subgroup analyses suggested that RIC resulted in superior overall survival due to a lower incidence of non-relapse mortality in patients with a poor performance status or a high HCT comorbidity index. In conclusion, RIC is a reasonable option for elderly patients with negative-MRD at HCT.

Hematopoietic stem cell transplantation for adults with Philadelphia chromosome-negative acute lymphoblastic leukemia in first remission: a position statement of the European Working Group for Adult Acute Lymphoblastic Leukemia (EWALL) and the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Allogeneic hematopoietic stem cell transplantation (HSCT) in first complete remission is a standard of care for adult patients with Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) and high risk of relapse. However, the stratification systems vary among study groups. Inadequate response at the level of minimal residual disease is the most commonly accepted factor indicating the need for alloHSCT. In this consensus paper on behalf of the European Working Group for Adult Acute Lymphoblastic Leukemia and the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize available evidence and reflect current clinical practice in major European study groups regarding both indications for HSCT and particular aspects of the procedure including the choice of donor, source of stem cells and conditioning. Finally, we propose recommendations for daily clinical practice as well as for planning of prospective trials.

Perspectives on the Use of a Medium-Dose Etoposide, Cyclophosphamide, and Total Body Irradiation Conditioning Regimen in Allogeneic Hematopoietic Stem Cell Transplantation: The Japanese Experience from 1993 to Present

The outcome for adults with acute lymphoblastic leukemia (ALL) treated with chemotherapy or autologous hematopoietic stem cell transplantation (HSCT) is poor. Therefore, allogeneic HSCT (allo HSCT) for adults aged less than 50 years with ALL is performed with myeloablative conditioning (MAC) regimens. Among the several MAC regimens, a conditioning regimen of 120 mg/kg (60mg/kg for two days) cyclophosphamide (CY) and 12 gray fractionated (12 gray in six fractions for three days) total body irradiation (TBI) is commonly used, resulting in a long term survival rate of approximately 50% when transplanted at the first complete remission. The addition of 30 mg/kg (15 mg/kg for two days) etoposide (ETP) to the CY/TBI regimen revealed an excellent outcome (a long-term survival rate of approximately 80%) in adults with ALL, showing lower relapse and non-relapse mortality rates. It is preferable to perform allo HSCT with a medium-dose ETP/CY/TBI conditioning regimen at the first complete remission in high-risk ALL patients and at the second complete remission (in addition to the first complete remission) in standard-risk ALL patients. The ETP dose and administration schedule are important factors for reducing the relapse and non-relapse mortality rates, preserving a better outcome. The pharmacological study suggests that the prolonged administration of ETP at a reduced dose is a promising treatment.