The outcome of full-intensity and reduced-intensity conditioning matched sibling or unrelated donor transplantation in adults with Philadelphia chromosome-negative acute lymphoblastic leukemia in first and second complete remission

Reduced intensity conditioning regimen of fludarabine, busulfan, ATG based haploidentical stem cell transplantation for older or unfit patients

Reduced-intensity conditioning (RIC) regimens allogeneic hematopoietic stem cell transplantation (HSCT) was developed for older patients or those with poor functional status. Haploidentical donor was appropriate alternative donor for patients without matched donors or patients with emergency disease state. However, there was few studies report the outcomes of RIC regimen of anti-thymocyte globulin (ATG) based haploidentical HSCT. The selection of the appropriate RIC regimen based on age and comorbidities in ATG-based haploidentical HSCT remains poorly described. To investigate the safety and efficacy of RIC regimen ATG-based haploidentical HSCT in older or unfit patients. Additionally, to explore the potential factors that impact the prognosis of RIC regimen of ATG-based haploidentical HSCT. We included a retrospective cohort of 63 patients with hematologic malignant diseases who underwent their first RIC haploidentical HSCT from November 2016 to June 2022 at our institutions. The conditioning regimen involved fludarabine (Flu) 30 mg/m²/kg 6 days combined with busulfan 3.2 mg/kg 2 days (Bu2) or 3 days (Bu3). ATG-Fresenius (ATG-F) was administered 10 mg/kg in total, ATG-thymoglobulin (ATG-T) was administered 6 mg/kg in total. The median age of patients in the entire cohort was 60 (32-67) years with a median follow-up of 496 (83-2182) days. There were 29 patients with AML, 20 patients with MDS, and 14 patients with ALL. A total of 32 patients underwent Bu2 RIC haplo-HSCT and 31 patients were treated with Bu3 RIC haplo-HSCT. The 2-year overall survival (OS) and 2-year disease-free survival (DFS) in whole cohort were 67.7% (95% confidence interval [CI], 53.8 - 85.1%) and 61.4% (95% CI, 48.8 - 77.3%) respectively. The cumulative incidence rates of grades II to IV and grades III to IV acute graft-versus-host disease (aGVHD) in whole cohort were 15.8% (95% CI, 4.8 - 19.6%) and 9.7% (95% CI, 0.0 - 11.8%) respectively. The 2-year cumulative incidence of chronic GVHD was 34.0% (95% CI, 18.9 - 46.3%). The 2-year cumulative incidence rates of relapse (IR) and non-relapse mortality (NRM) rates in whole cohort were 27.5% (95% CI, 14.5 - 33.7%) and 11.6% (95% CI, 2.2 - 21.9%) respectively. The probability of 2-year OS were 60.2% (95% CI:42.5-85.3%) in Bu2 and 85.5%(95% CI:73.0-100%) in Bu3 group respectively(P = 0.150). The probability of 2-year DFS were 49.7% (95% CI:33.0-74.8%) in Bu2 and 72.6% (95% CI:55.5-95.5%) in Bu3 group respectively (P = 0.045). The 2-year IR of Bu2 group was significantly higher than Bu3 group (P = 0.045). However, the 2-year NRM were not significantly different between Bu2 and Bu3 group(P > 0.05). In multivariable analysis, RIC regimen of Bu3 had superior OS and DFS than Bu2 group respectively [HR 0.42, 95% CI 0.18-0.98; P = 0.044; HR 0.34, 95% CI 0.14-0.86; P = 0.022]. Besides, RIC regimen of Bu3 had lower IR than Bu2 group [HR 0.34, 95% CI 0.13-0.89; P = 0.029]. The RIC regimen of ATG-based haploidentical HSCT is a safe and effective treatment option for patients who are older or have poor functional status. In particular, a relatively high-intensity pre-treatment regimen consisting of Bu achieves significant improvements in OS and DFS, thus providing more favorable post-transplantation clinical outcomes.

Allogeneic Stem Cell Transplantation in Patients >40 Years of Age With Acute Lymphoblastic Leukemia: Reduced Intensity Versus Myeloablative Conditioning

BACKGROUND

The outcome in older patients with acute lymphoblastic leukemia (ALL) remains unsatisfactory due to high relapse and nonrelapse mortality (NRM) rates. Allogeneic stem cell transplantation (alloHSCT) as postremission therapy has an important role in reducing relapse rate, albeit its application is limited in older adult patients due to alloHSCT-related morbidity and mortality. Reduced-intensity conditioning (RIC) alloHSCT has been developed as a less toxic conditioning regimen, but comparative studies with myeloablative conditioning (MAC) are limited in patients with ALL.

METHODS

In this retrospective study, RIC-alloHSCT (n = 111) was compared with MAC-alloHSCT (n = 77) in patients aged 41 to 65 y with ALL in first complete remission. MAC was predominantly applied by combining high-dose total body irradiation and cyclophosphamide, whereas RIC mainly consisted of fludarabine and 2 Gy total body irradiation.

RESULTS

Unadjusted overall survival was 54% (95% confidence interval [CI], 42%-65%) at 5 y in MAC recipients compared with 39% (95% CI, 29%-49%) in RIC recipients. Overall survival and relapse-free survival were not significantly associated with type of conditioning after adjusted for the covariates age, leukemia risk status at diagnosis, donor type, and donor and recipient gender combination. NRM was significantly lower after RIC (subdistribution hazard ratio: 0.41, 95% CI, 0.22-0.78; P  = 0.006), whereas relapse was significantly higher (subdistribution hazard ratio: 3.04, 95% CI, 1.71-5.40; P < 0.001).

CONCLUSIONS

Collectively, RIC-alloHSCT has resulted in less NRM, but it was also found to be associated with a significantly higher relapse rate. These results suggest that MAC-alloHSCT may provide a more effective type of consolidation therapy for the reduction of relapse and that RIC-alloHSCT may be restricted to patients at higher risk for NRM.

The current landscape: Allogeneic hematopoietic stem cell transplant for acute lymphoblastic leukemia

One of the consistent features in development of hematopoietic stem cell transplant (HCT) for Acute Lymphoblastic Leukemia (ALL) is the rapidity with which discoveries in the laboratory are translated into innovations in clinical care. Just a few years after murine studies demonstrated that rescue from radiation induced marrow failure is mediated by cellular not humoral factors, E. Donnall Thomas reported on the transfer of bone marrow cells into irradiated leukemia patients. This was followed quickly by the first descriptions of Graft versus Leukemia (GvL) effect and Graft versus Host Disease (GvHD). Despite the pivotal nature of these findings, early human transplants were uniformly unsuccessful and identified the challenges that continue to thwart transplanters today - leukemic relapse, regimen related toxicity, and GvHD. While originally only an option for young, fit patients with a matched family donor, expansion of the donor pool to include unrelated donors, umbilical cord blood units, and more recently the growing use of haploidentical donors have all made transplant a more accessible therapy for patients with ALL. Novel agents for conditioning, prevention and treatment of GvHD have improved outcomes and investigators continue to develop novel treatment strategies that balance regimen related toxicity with disease control. Our evolving understanding of how to prevent and treat GvHD and how to prevent relapse are incorporated into novel clinical trials that are expected to further improve outcomes. Here we review current considerations and future directions for both adult and pediatric patients undergoing HCT for ALL, including indication for transplant, donor selection, cytoreductive regimens, and outcomes.

Allogeneic stem cell transplant outcomes between TBI-containing reduced intensity and myeloablative conditioning regimens for ALL in complete remission

Total-body irradiation (TBI)-based conditioning regimen is preferred in acute lymphoblastic leukemia (ALL). We retrospectively evaluated allogeneic stem cell transplant (alloSCT) outcomes of 86 adult ALL patients in complete remission (CR) who received TBI-containing reduced intensity (RIC) (Flu/Mel/TBI = 31) and myeloablative conditioning (MAC) (VP16/TBI = 47; CY/TBI = 8) between January 2005 and December 2019. All patients received peripheral blood allografts. Patients in the RIC group were older than the MAC group (61 years old versus 36 years, p < .001). Donor was 8/8 HLA-matched in 83% and unrelated in 65% of patients. Three-year survival was 56.04% for RIC and 69.9% for MAC (HR 0.64; p = .19). Propensity score-based multivariable Cox analyses (PSCA) did not demonstrate any difference in grade III-IV acute graft versus host disease (GVHD) (SHR 1.23, p = .91), chronic GVHD (SHR 0.92, p = .88), survival (HR 0.94, p = .92), and relapse-free survival (HR 0.66, p = .47) between both groups, while relapse rate was lower (SHR 0.21, p = .02) for MAC compared to RIC. Our study did not demonstrate any difference in survival for TBI-containing RIC and MAC alloSCT for adult ALL in CR.

ALL-RIC trial protocol: a comparison of reduced dose total body irradiation (TBI) and cyclophosphamide with fludarabine and melphalan reduced intensity conditioning in adults with acute lymphoblastic leukaemia (ALL) in complete remission

INTRODUCTION

The usage of a T-cell depleted, reduced intensity conditioning (RIC) approach to haematopoietic cell transplantation (HCT) in adult patients with acute lymphoblastic leukaemia (ALL) over 40 years of age and in first complete remission (CR) has resulted in encouraging rates of event-free and overall survival in a population of adults with high risk disease. However, relapse rates remain high-with disease progression being the major cause of treatment failure. Using different, more powerful conditioning approaches is the logical next step in examining the role of RIC allogeneic HCT in adult ALL.

METHODS AND ANALYSIS

The ALL-RIC trial is a two-arm, phase II, multicentre, randomised clinical trial in adult patients with ALL in first or second CR, who are undergoing allogeneic HCT. Comparison of a novel RIC transplant conditioning regimen using reduced-dose total body irradiation (TBI), cyclophosphamide and alemtuzumab, is made against a standardised RIC approach using fludarabine, melphalan and alemtuzumab. The primary outcome of the study is disease-free survival at 3 years, defined as time from randomisation to the first of either relapse or death from any cause. Patients who are still alive and progression-free at the end of the trial will be censored at their last date known to be alive. Secondary outcomes include overall survival and non-relapse mortality.

ETHICS AND DISSEMINATION

The protocol was approved by the East Midlands-Leicester Central Research Ethics committee (18/EM/0112). Initial approval was received on 12 June 2018. Current protocol version (V.6.0) approval obtained on 18 November 2019. The Medicines and Healthcare products Regulatory Agency (MHRA) also approved all protocol versions. The results of this trial will be disseminated through national and international presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

EudraCT Number: 2017-004800-23.ISRCTN99927695.

How I prevent and treat central nervous system disease in adults with acute lymphoblastic leukemia

The central nervous system (CNS) is the most important site of extramedullary disease in adults with acute lymphoblastic leukemia (ALL). Although CNS disease is identified only in a minority of patients at the time of diagnosis, subsequent CNS relapses (either isolated or concurrent with other sites) occur in some patients even after the delivery of prophylactic therapy targeted to the CNS. Historically, prophylaxis against CNS disease has included intrathecal (IT) chemotherapy and radiotherapy (RT), although the latter is being used with decreasing frequency. Treatment of a CNS relapse usually involves intensive systemic therapy and cranial or craniospinal RT along with IT therapy and consideration of allogeneic hematopoietic cell transplant. However, short- and long-term toxicities can make these interventions prohibitively risky, particularly for older adults. As new antibody-based immunotherapy agents have been approved for relapsed/refractory B-cell ALL, their use specifically for patients with CNS disease is an area of keen interest not only because of the potential for efficacy but also concerns of unique toxicity to the CNS. In this review, we discuss data-driven approaches for these common and challenging clinical scenarios as well as highlight how recent findings potentially support the use of novel immunotherapeutic strategies for CNS disease.

Thiotepa, busulfan and fludarabine conditioning-regimen is a promising approach for older adult patients with acute lymphoblastic leukemia treated with allogeneic stem cell transplantation

For acute lymphoblastic leukemia (ALL) patients, total body irradiation (TBI)- based conditioning regimens are the first choice specially in young population. However, several studies have shown an equivalence in clinical outcomes with thiotepa-based conditioning regimen. We performed a retrospective study to evaluate the outcome of adult ALL patients who received allogeneic hematopoietic stem cell transplantation (allo-HCT) with a thiotepa-busulfan-fludarabine (TBF) myeloablative conditioning regimen with reduced toxicity. Fifty-five patients received a TBF regimen. The median age of the patients was 51 years (range, 17 to 72.4). Most patients had a diagnosis of B-ALL (93%) with 7% having T-ALL. Two - and 5-year overall survival was 73.2% and 64%, respectively. At 2 years, leukemia-free survival and GVHD-free, relapse-free survival were 59.5% and 57.6%, and at 5 years, 53.4% and 51.8%, respectively. The 5-year non-relapse mortality was 15%. The day 180 cumulative incidence (CI) of grade II-IV acute GVHD and grade III-IV acute GVHD were 38.2% and 5.5%, respectively. At 2 years, the CI of chronic GVHD and extensive chronic GVHD was 16.9% and 1.9%, respectively. Our study results do suggest that using TBF as the conditioning regimen in adult ALL patients is a promising option with acceptable toxicity.

Long-term follow up of patients with hematological malignancies treated with total body irradiation using intensity modulated radiation therapy

BACKGROUND

With the advent of modern radiation treatment technologies such as intensity modulated radiation therapy (IMRT), there has been increasing interest in its use for total body irradiation (TBI) conditioning regimens for hematopoietic cell transplantation (HCT) to achieve lower doses to critical organs such as the lungs and kidneys. Although this has been reported on in early studies, long-term safety and efficacy data is limited.

METHODS

We performed a single institution matched-pair retrospective analysis of patients treated with IMRT TBI and standard TBI between 2010 and 2020 to provide data on long-term outcomes. Patients with hematologic malignancies, who could not tolerate standing for traditional TBI or who received prior radiation received IMRT TBI. Patients were matched based on age, diagnosis, disease status, and year of transplant, and were matched 2:1 to the standard TBI and IMRT TBI cohorts. Patient and treatment characteristics, toxicity, graft-versus-host disease (GVHD), dosimetry, and outcomes were evaluated for each cohort.

RESULTS

A total of 13 patients met inclusion criteria for the IMRT cohort, leading to 26 patients in the standard TBI cohort. There was no significant difference in relevant clinical factors between the cohorts. Reasons for using IMRT over conventional TBI included being unable to stand (n=5), prior radiation (n=5), and pediatric patient requiring anesthesia (n=3). Among living patients, median follow-up for all patients was 5.1 years in the IMRT TBI cohort and 5.5 years in the standard TBI cohort. The 5-yr estimate of OS was 68% in the IMRT TBI cohort and 60% in the standard TBI cohort (p=0.706). The 5-yr estimate of RFS was 54% in the IMRT TBI cohort and 60% in the standard TBI cohort (p=0.529). There was no clinically significant pneumonitis, nephritis, hypothyroidism, or cataracts reported in the IMRT TBI cohort. 41.7% of patients in the IMRT TBI cohort and 79.2% of patients in the standard TBI cohort experienced Grade II-IV acute GVHD (p=0.023).

CONCLUSIONS

IMRT TBI appears to lead to favorable long-term outcome and dosimetry, and therefore potentially improved long-term toxicity profile compared to conventional TBI. IMRT TBI warrants further investigation as part of larger prospective trials.

Ph-like gene alterations and complex chromosomal abnormalities are frequent in patients with acute lymphoblastic leukemia experiencing relapse after allogeneic hematopoietic cell transplantation

The new aspect of our work is to reveal that Ph-like alterations are common among patients with Ph-ALL experiencing relapse after hematopoietic cell transplantation (HCT), despite acquisition of MRD-negative complete responses prior to transplant. This is also the central finding of our work. Therefore, the anticipated benefits of HCT appear diminished among this patient subset; such patients may be better served with efforts to further increase MRD depth prior to HCT, or alternative therapies.

In-vivo T-cell depleted reduced-intensity conditioned allogeneic haematopoietic stem-cell transplantation for patients with acute lymphoblastic leukaemia in first remission: results from the prospective, single-arm evaluation of the UKALL14 trial

BACKGROUND

The outcome of chemotherapy in patients older than 40 years with acute lymphoblastic leukaemia is poor and myeloablative allogeneic haematopoietic stem-cell transplantation (HSCT) has a high transplant-related mortality (TRM) in this age cohort. The aim of this study was to assess the activity and safety of reduced-intensity conditioned allogeneic HSCT in this patient population.

METHODS

This was a single-arm, prospective study within the UKALL14 trial done in 46 centres in the UK, which recruited patients to the transplantation substudy. Participants in UKALL14 had B-cell or T-cell acute lymphoblastic leukaemia, were aged 25-65 years (BCR-ABL1-negative) or 18-65 years (BCR-ABL1-positive), and for this subcohort had a fit, matched sibling donor or an 8 out of 8 allelic matched unrelated donor (HLA-A, HLA-B, HLA-C, and HLA-DR). On June 20, 2014, the protocol was amended to allow 7 out of 8 matched unrelated donors if the patient had high risk cytogenetics or was minimal residual disease (MRD)-positive after the second induction course. Patients were given fludarabine, melphalan, and alemtuzumab (FMA; intravenous fludarabine 30 mg/m² on days -6 to -2, melphalan 140 mg/m² on day -2, and alemtuzumab 30 mg on day -1 [sibling donor] and days -2 and -1 [unrelated donor]) before allogeneic HSCT (aged ≥41 years patient pathway). Donor lymphocyte infusions were given from 6 months for mixed chimerism or MRD. The primary endpoint was event-free survival and secondary and transplantation-specific endpoints included overall survival, relapse incidence, TRM, and acute and chronic graft-versus-host disease (GVHD). This study is registered with ClinicalTrials.gov, NCT01085617.

FINDINGS

From Feb 22, 2011, to July 26, 2018, 249 patients (236 aged ≥41 years and 13 younger than 41 years) considered unfit for a myeloablative allograft received an FMA reduced-intensity conditioned HSCT. 138 (55%) patients were male and 111 (45%) were female. 88 (35%) participants received transplantations from a sibling donor and 160 (64%) received transplantations from unrelated donors. 211 (85%) participants had B-precursor acute lymphoblastic leukaemia. High-risk cytogenetics were present in 43 (22%) and another 63 (25%) participants were BCR-ABL1-positive. At median follow-up of 49 months (IQR 36-70), 4-year event-free survival was 46·8% (95% CI 40·1-53·2) and 4-year overall survival was 54·8% (48·0-61·2). 4-year cumulative incidence of relapse was 33·6% (27·9-40·2) and 4-year TRM was 19·6% (15·1-25·3). 27 (56%) of 48 patients with TRM had infection as the named cause of death. Seven (15%) of 48 patients had fungal infections, 13 (27%) patients had bacterial infections (six gram-negative), and 11 (23%) had viral infections (three cytomegalovirus and two Epstein-Barr virus). Acute GVHD grade 2-4 occurred in 29 (12%) of 247 patients and grade 3-4 occurred in 12 (5%) patients. Chronic GVHD incidence was 84 (37%) of 228 patients (50 [22%] had extensive chronic GVHD). 49 (30%) of 162 patients had detectable end-of-induction MRD, which portended worse outcomes with event-free survival (HR 2·40 [95% CI 1·46-3·93]) and time-to-relapse (HR 2·41 [1·29-4·48]).

INTERPRETATION

FMA reduced-intensity conditioned allogeneic HSCT in older patients with acute lymphoblastic leukaemia in first complete remission provided good disease control with moderate GVHD, resulting in better-than-expected event-free survival and overall survival in this high-risk population. Strategies to reduce infection-related TRM will further improve outcomes.

FUNDING

Cancer Research UK.

Treatment of Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia in Adults

Simple Summary

Outcome of patients with Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph+ ALL) dramatically improved during the past 20 years with the advent of tyrosine kinase inhibitors and monoclonal antibodies. Their great efficacy in young and fit patients led to question our reliance on chemotherapy and allogeneic hematopoietic stem cell transplantation. Moreover, these well-tolerated treatments can be safely administrated even in the elderly that represent the majority of Ph+ ALL patient. This review will focus on the recent changes of paradigm in the management of Ph+ ALL patients and the development of novel therapeutic strategies.

Abstract

Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph+ ALL) is the most common subtype of B-ALL in adults and its incidence increases with age. It is characterized by the presence of BCR-ABL oncoprotein that plays a central role in the leukemogenesis of Ph+ ALL. Ph+ ALL patients traditionally had dismal prognosis and long-term survivors were only observed among patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR1). However, feasibility of allo-HSCT is limited in this elderly population. Fortunately, development of increasingly powerful tyrosine kinase inhibitors (TKIs) from the beginning of the 2000′s dramatically improved the prognosis of Ph+ ALL patients with complete response rates above 90%, deep molecular responses and prolonged survival, altogether with good tolerance. TKIs became the keystone of Ph+ ALL management and their great efficacy led to develop reduced-intensity chemotherapy backbones. Subsequent introduction of blinatumomab allowed going further with development of chemo free strategies. This review will focus on these amazing recent advances as well as novel therapeutic strategies in adult Ph+ ALL.

Pharmacotherapeutic management of T-cell acute lymphoblastic leukemia in adults: an update of the literature

INTRODUCTION

T-cell acute lymphoblastic leukemia (T-ALL) is a rare but potentially life-threatening heterogeneous hematologic malignancy that requires prompt diagnosis and treatment by hematologists. So far, therapeutic advances have been achieved in the management of this disease mainly by adopting pediatric-like regimens, and cure rates are significantly worse than in childhood. In T-ALL, less than 70% of adults achieve long-term survival. The prognosis after relapse is still very poor. Hence, there is urgent need to improve therapy of T-ALL by testing new compounds and combinations for the treatment of this disease.

AREAS COVERED

This review provides a comprehensive update on the most recent treatment approaches in adults with de novo and relapsed/refractory adult T-ALL.

EXPERT OPINION

Intensifying chemotherapy may reduce the incidence of recurrent disease in adult patients, but it has not come without a cost. Novel agents with selective T-ALL activity (e.g. nelarabine) may improve survival in some patient subsets. Due to modern genomic and transcriptomic techniques, various novel potential targets might change the treatment landscape in the next few years and will, hopefully alongside with cellular therapies, augment the therapeutic armamentarium in the near future.

Conditioning Regimens for Frail Patients with Acute Leukemia Undergoing Allogeneic Stem Cell Transplant: How to Strike Gently

Despite the recent dramatic progress in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) therapy, allogeneic transplant remains a mainstay of treatment for patients with acute leukemia. The availability of novel compounds and low intensity chemotherapy regimens made it possible for a significant proportion of elderly and comorbid patients with AML or ALL to undergo curative treatment protocols. In addition, the expansion of donor availability and the recent dramatic progress in haploidentical stem cell transplant, allow the identification of an available donor for nearly every patient. Therefore, an increasing number of transplants are currently performed in elderly and frail patients with AML or ALL. However, allo-Hematopoietic stem cell transplant (HSCT) in this delicate setting represents an important challenge, especially regarding the selection of the conditioning protocol. Ideally, conditioning intensity should be reduced as much as possible; however, in patients with acute leukemia relapse remains the major cause of transplant failure. In this article we present modern tools to assess the patient health status before transplant, review the available data on the outcome of frail AML an ALL patients undergoing allo-HSCT, and discuss how preparatory regimens can be optimized in this setting.

Volumetric Modulated Arc Therapy Enabled Total Body Irradiation (VMAT-TBI): Six-year Clinical Experience and Treatment Outcomes

Total body irradiation is an important part of the conditioning regimens frequently used to prepare patients for allogeneic hematopoietic stem cell transplantation (SCT). Volumetric-modulated arc therapy enabled total body irradiation (VMAT-TBI), an alternative to conventional TBI (cTBI), is a novel radiotherapy treatment technique that has been implemented and investigated in our institution. The purpose of this study is to (1) report our six-year clinical experience in terms of treatment planning strategy and delivery time and (2) evaluate the clinical outcomes and toxicities in our cohort of patients treated with VMAT-TBI. This is a retrospective single center study. Forty-four patients at our institution received VMAT-TBI and chemotherapy conditioning followed by allogeneic SCT between 2014 and 2020. Thirty-two patients (73%) received standard-dose TBI (12-13.2 Gy in 6-8 fractions twice daily), whereas 12 (27%) received low-dose TBI (2-4 Gy in one fraction). Treatment planning, delivery, and treatment outcome data including overall survival (OS), relapse-free survival (RFS), and toxicities were analyzed. The developed VMAT-TBI planning strategy consistently generated plans satisfying our dose constraints, with planning target volume coverage >90%, mean lung dose ∼50% to 75% of prescription dose, and minimal hotspots in critical organs. Most of the treatment deliveries were <100 minutes (range 33-147, mean 72). The median follow-up was 26 months. At the last follow-up, 34 of 44 (77%) of patients were alive, with 1- and 2-year OS of 90% and 79% and RFS of 88% and 71%, respectively. The most common grade 3+ toxicities observed were mucositis (31 patients [71%]) and nephrotoxicity (6 patients [13%]), both of which were deemed multifactorial in cause. Four patients (9%) in standard-dose cohort developed grade 3+ pneumonitis, with 3 cases in the setting of documented respiratory infection and only 1 (2%) deemed likely related to radiation alone. VMAT-TBI provides a safe alternative to cTBI. The dose modulation capability of VMAT-TBI may lead to new treatment strategies, such as simultaneous boost and further critical organ sparing, for better malignant cell eradication, immune suppression, and lower toxicities.

T-Cell Acute Lymphoblastic Leukemia-Current Concepts in Molecular Biology and Management

T-cell acute lymphoblastic leukemia (T-ALL) is an uncommon, yet aggressive leukemia that accounts for approximately one-fourth of acute lymphoblastic leukemia (ALL) cases. CDKN2A/CDKN2B and NOTCH1 are the most common mutated genes in T-ALL. Children and young adults are treated with pediatric intensive regimens and have superior outcomes compared to older adults. In children and young adults, Nelarabine added to frontline chemotherapy improves outcomes and end of consolidation measurable residual disease has emerged as the most valuable prognostic marker. While outcomes for de-novo disease are steadily improving, patients with relapsed and refractory T-ALL fare poorly. Newer targeted therapies are being studied in large clinical trials and have the potential to further improve outcomes. The role of allogeneic stem cell transplant (HSCT) is evolving due to the increased use of pediatric-inspired regimens and MRD monitoring. In this review we will discuss the biology, treatment, and outcomes in pediatric and adult T-ALL.

Acute Lymphoblastic Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Acute Lymphoblastic Leukemia (ALL) focus on the classification of ALL subtypes based on immunophenotype and cytogenetic/molecular markers; risk assessment and stratification for risk-adapted therapy; treatment strategies for Philadelphia chromosome (Ph)-positive and Ph-negative ALL for both adolescent and young adult and adult patients; and supportive care considerations. Given the complexity of ALL treatment regimens and the required supportive care measures, the NCCN ALL Panel recommends that patients be treated at a specialized cancer center with expertise in the management of ALL This portion of the Guidelines focuses on the management of Ph-positive and Ph-negative ALL in adolescents and young adults, and management in relapsed settings.

The differential effect of disease status at allogeneic hematopoietic cell transplantation on outcomes in acute myeloid and lymphoblastic leukemia

This study aimed to compare the effect of disease status at the time of allogeneic hematopoietic cell transplantation (HCT) on post-transplant outcomes between acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Japanese nationwide registry data for 6901 patients with AML and 2469 patients with ALL were analyzed. In this study, 2850 (41%), 937 (14%), 62 (1%), and 3052 (44%) AML patients and 1751 (71%), 265 (11%), 23 (1%), and 430 (17%) ALL patients underwent transplantation in first complete remission (CR1), second CR (CR2), third or subsequent CR (CR3 +), and non-CR, respectively. The probabilities of overall survival at 5 years for patients transplanted in CR1, CR2, CR3 + , and non-CR were 58%, 61%, 41%, and 26% for AML patients and 67%, 45%, 20%, and 21% for ALL patients, respectively. Multivariate analyses revealed that the risks of relapse and overall mortality were similar for AML patients transplanted in CR1 and CR2 (P = 0.672 and P = 0.703), whereas they were higher for ALL patients transplanted in CR2 than for those transplanted in CR1 (P < 0.001 for both). The risks of relapse and overall mortality for those transplanted in CR3 + and non-CR increased in a stepwise manner for both diseases, with the relevance being stronger for ALL than for AML patients. These results suggest a significant difference in the effect of disease status at HCT on post-transplant outcomes in AML and ALL. Further investigation to incorporate measurable residual disease data is warranted.

Novel Indicators of Transplant Outcomes for PhALL: Current Molecular-Relapse-Free Survival

Molecular relapse after allogeneic hematopoietic cell transplantation (allo-HCT) has been thought to predict clinical relapse in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (PhALL). Tyrosine kinase inhibitor (TKI) administration after allo-HCT may dynamically change the status from molecular relapse to molecular remission, but these state changes cannot be accurately represented by conventional survival indicators such as relapse-free survival, where events are usually considered irreversible. We aimed to develop novel indicators of transplant outcomes for allo-HCT recipients with PhALL and to visualize current molecular-relapse-free survival (CMRFS) and current on-TKI status (CTKI), treating molecular relapse or TKI administration after allo-HCT as a reversible event. We retrospectively analyzed 286 patients with PhALL who received allo-HCT between 2000 and 2016 in order to develop the indicators. CMRFS was defined as the probability of molecular remission without clinical relapse or death at any time after allo-HCT. Similarly, CTKI was defined as the probability of TKI administration without clinical relapse or death at any time after allo-HCT. The 1- and 5-year CMRFS rates were 67% and 59%, respectively, whereas the 1- and 5-year conventional molecular relapse-free survival rates were 42% and 37%. The 1- and 5-year CTKI rates were 14% and 8%, respectively. In a post hoc analysis focusing on patients who had achieved a molecular complete remission within 6 weeks (n = 201), the 5-year CMRFS rate (71%) was similar to the 5-year conventional molecular relapse-free survival (molRFS) rate (70%) in the non-TKI group. On the other hand, the 5-year CMRFS rate in the TKI group was 61%, whereas the 5-year conventional molRFS rate was only 38%. CMRFS and CTKI might become useful indicators of transplant success in terms of survival, leukemia-free status, and treatment-free status at any time point. Future extension of these survival models to other clinical situations is warranted.

Hematopoietic cell transplantation for acute lymphoblastic leukemia: review of current indications and outcomes

The treatment landscape for patients with acute lymphoblastic leukemia (ALL) is changing. Continued investigation into the biology of ALL, and broader use and more precise methods of measuring residual disease allow for improved risk stratification of patients and identification of the subset of patients at greatest risk of disease relapse and who may benefit from hematopoietic cell transplantation (HCT) in first complete remission. Further, recent advances in HCT preparative regimens, donor selection, graft manipulation, and graft-versus-host disease prophylaxis and treatment have resulted in fewer transplant-related morbidities and mortality and better survival outcomes. Finally, the development of effective immunotherapeutic salvage agents, such as the chimeric antigen receptor T-cell therapy, tisagenlecleucel, have significantly changed the treatment landscape of this disease, allowing patients with advanced disease to be considered for HCT with curative intent. In this review, we will provide an update on the indications and outcome of pediatric and adult ALL.

Measurable residual disease affects allogeneic hematopoietic cell transplantation in Ph+ ALL during both CR1 and CR2

Although measurable residual disease (MRD) at the time of allogeneic hematopoietic cell transplantation (allo-HCT) has been reported to be an important prognostic factor for Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) during first complete remission (CR1), the prognostic impact of MRD is unclear during second CR (CR2). To clarify the impact of MRD for both CR1 and CR2, we analyzed data from a registry database including 1625 adult patients with Ph+ ALL who underwent first allo-HCT during either CR1 or CR2 between 2002 and 2017. Adjusted overall and leukemia-free survival rates at 4 years were 71% and 64%, respectively, for patients undergoing allo-HCT during CR1 with MRD-, 55% and 43% during CR1 with MRD+, 51% and 49% during CR2 with MRD-, and 38% and 29% during CR2 with MRD+. Although survival rates were significantly better among patients with CR1 MRD- than among patients with CR2 MRD-, no significant difference was observed in survival rate between patients with CR1 MRD+ and CR2 MRD-. Relapse rates after 4 years were 16% in patients with CR1 MRD-, 29% in CR1 MRD+, 21% in patients with CR2 MRD-, and 46% in patients with CR2 MRD+. No significant difference was identified in relapse rate between patients with CR1 MRD- and CR2 MRD-. CR2 MRD- was not a significant risk factor for relapse in multivariate analysis (hazard ratio, 1.26; 95% confidence interval, 0.69-2.29; P = .45 vs CR1 MRD-). MRD at time of allo-HCT was an important risk factor in patients with Ph+ ALL during both CR1 and CR2.

Inferior outcomes with reduced intensity conditioning followed by allogeneic hematopoietic cell transplantation in fit individuals with acute lymphoblastic leukemia: a Canadian single-center study and a comparison to registry data

Allogeneic hematopoietic cell transplantation (HCT) can offer cure to some patients with acute lymphoblastic leukemia (ALL). It remains unclear how conditioning intensity affects transplant outcomes in ALL. In this retrospective study, we compared outcomes between 27 patients <60 who received reduced intensity conditioning (RIC) at Princess Margaret Hospital Cancer Center (PMCC) and 226 Cell Therapy Transplant Canada (CTTC) age-matched controls who received myeloablative conditioning (MAC) between 2007 and 2018. Compared to CTTC patients, PMCC patients had an inferior 2-y OS: 0.29 (95% CI: 0.11-0.49) vs 0.63 (0.56-0.70), HR = 2.10 (1.23-3.55), p = 0.006, higher TRM: 0.41 (0.22-0.60) vs 0.24 (0.18-0.30), HR = 2.00 (1.05-3.81), p = 0.04 and a trend toward increased risk of relapse: 0.36 (0.17-0.56) versus 0.17 (0.12-0.22), HR = 1.72 (0.82-3.62), p = 0.15. In multivariate analysis, RIC and the use of T-cell depletion (TCD) were associated with inferior OS. In ALL patients <60, the use of RIC with TCD is associated with inferior allogeneic HCT outcomes.

Total Body Irradiation for Hematopoietic Stem Cell Transplantation: What Can We Agree on?

Total body irradiation (TBI), used as part of the conditioning regimen prior to allogeneic and autologous hematopoietic cell transplantation, is the delivery of a relatively homogeneous dose of radiation to the entire body. TBI has a dual role, being cytotoxic and immunosuppressive. This allows it to eliminate disease and create “space” in the marrow while also impairing the immune system from rejecting the foreign donor cells being transplanted. Advantages that TBI may have over chemotherapy alone are that it may achieve greater tumour cytotoxicity and better tissue penetration than chemotherapy as its delivery is independent of vascular supply and physiologic barriers such as renal and hepatic function. Therefore, the so-called “sanctuary” sites such as the central nervous system (CNS), testes, and orbits or other sites with limited blood supply are not off-limits to radiation. Nevertheless, TBI is hampered by challenging logistics of administration, coordination between hematology and radiation oncology departments, increased rates of acute treatment-related morbidity and mortality along with late toxicity to other tissues. Newer technologies and a better understanding of the biology and physics of TBI has allowed the field to develop novel delivery systems which may help to deliver radiation more safely while maintaining its efficacy. However, continued research and collaboration are needed to determine the best approaches for the use of TBI in the future.

Stopping tyrosine kinase inhibitors started after allogeneic HCT in patients with Philadelphia chromosome-positive leukemia

For patients with Philadelphia chromosome (Ph)-positive leukemia, there is no consensus regarding how long tyrosine kinase inhibitors (TKI) should be given or whether TKI could be stopped if TKI is administrated after allogeneic hematopoietic cell transplantation (allo-HCT). We analyzed relapse-free survival (RFS) in 92 allo-HCT patients who received TKI for >3 months after allo-HCT, and aimed to develop a novel indicator, called as current TKI- & relapse-free (cTRFree) achievement. TKI after allo-HCT was started as planned in 39 patients, based on measurable residual disease (MRD) in 53 at a median of 152 days after allo-HCT. There was no difference in post-TKI RFS between the planned and MRD-based starting groups (P = 0.69). Second-generation TKIs were associated with superior RFS in Ph-positive acute leukemia (HR 2.71, P = 0.031). TKI was stopped before relapse in 48 patients. Stopping TKI as a time-dependent covariate was not associated with subsequent hematological relapse (HR 1.18, P = 0.72). In the TKI-stop group, TKI administration for >6 months tended to be associated with superior RFS (HR = 0.30, P = 0.08). As an indicator of transplant success, cTRFree was 35% 5 years after starting TKI. TKI could be stopped for recipients with sustained undetectable MRD. However, further prospective studies will be required to establish clinical recommendations.

Haematopoietic Stem Cell Transplantation in Adolescents and Young Adults With Acute Lymphoblastic Leukaemia: Special Considerations and Challenges

Adolescents and young adults (AYAs) represent a challenging group of acute lymphoblastic leukaemia (ALL) patients with specific needs. While there is growing evidence from comparative studies that this age group profits from intensified paediatric-based chemotherapy, the impact and optimal implementation of haematopoietic stem cell transplantation (HSCT) in the overall treatment strategy is less clear. Over recent years, improved survival rates after myeloablative allogeneic HSCT for ALL have been reported similarly for AYAs and children despite differences in transplantation practise. Still, AYAs appear to have inferior outcomes and an increased risk of treatment-related morbidity and mortality in comparison with children. To further improve HSCT outcomes and reduce toxicities in AYAs, accurate stratification and evaluation of additional or alternative targeted treatment options are crucial, based on specific molecular and immunological characterisation of ALL and minimal residual disease (MRD) assessment during therapy. Age-specific factors such as increased acute toxicities and poorer adherence to treatment as well as late sequelae might influence treatment decisions. In addition, educational, social, work, emotional, and sexual aspects during this very crucial period of life need to be considered. In this review, we summarise the key findings of recent studies on treatment approach and outcomes in this vulnerable patient group after HSCT, turning our attention to the different approaches applied in paediatric and adult centres. We focus on the specific needs of AYAs with ALL regarding social aspects and supportive care to handle complications as well as fertility issues. Finally, we comment on potential areas of future research and concisely debate the capacity of currently available immunotherapies to reduce toxicity and further improve survival in this challenging patient group.

The challenge to further improvements in survival of patients with T-ALL: Current treatments and new insights from disease pathogenesis

Survival rates for children and adult patients with T-cell acute lymphoblastic leukemia (T-ALL) have improved during the past decade due to optimization of frontline multiagent chemotherapy regimens. The outcome for relapsed T-ALL after initial intensive chemotherapy is frequently fatal, however, because no effective salvage regimens have been developed. Immunotherapy and small molecule inhibitors are beginning to be tested in T-ALL and have the potential to advance the treatment, especially the frontline regimen by eradicating minimal residual disease thus inducing more durable remissions. In this paper, I review the current chemotherapy regimens for adult patients with T-ALL and summarize the novel immunotherapies and small molecule inhibitors that are currently in early phase clinical trials.

Outcome predictors after retransplantation in relapsed acute lymphoblastic leukemia: a multicenter, retrospective study

Retransplantation is the only curative treatment option for patients with acute lymphoblastic leukemia (ALL) that has relapsed after allogeneic hematopoietic cell transplantation (allo-HCT); however, data in this setting remain scant. Hence, this multicenter, retrospective study aims to determine outcome predictors after retransplantation in relapsed ALL. We examined 55 recipients who underwent multiple allo-HCTs during 2006-2018. The 2-year overall survival (OS), progression-free survival (PFS), and non-relapse mortality rates were 35.9%, 29.1%, and 23.6%, respectively. We observed a trend of better outcome in Ph + ALL (n = 22) patients compared with non-Ph ALL (n = 33) patients; the 2-year PFS was 40.9% versus 21.2%, indicating a beneficial effect of more potent second- or third-generation tyrosine kinase inhibitors. Univariate analysis revealed that late relapse after the previous transplant was the only significant predictor of better transplant outcome among Ph + ALL patients, whereas factors related to prolonged OS/PFS in non-Ph ALL patients were late relapse after the previous transplant, longer duration from disease relapse/progression to second or more allo-HCT, disease status at the transplantation, and good performance status. Nevertheless, further investigations are warranted to determine whether novel molecular-targeted agents with higher efficacy and fewer toxicities could exceed conventional chemotherapies as a bridging strategy to next allo-HCT and improve the outcomes of non-Ph ALL patients.

Myeloablative vs reduced intensity T-cell-replete haploidentical transplantation for hematologic malignancy

In the absence of prospective studies that examine the effect of conditioning regimen intensity after T-cell-replete haploidentical transplant for acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), and myelodysplastic syndrome (MDS), a retrospective cohort analysis was performed. Of the 1325 eligible patients (AML, n = 818; ALL, n = 286; and MDS, n = 221), 526 patients received a myeloablative regimen and 799 received a reduced-intensity regimen. Graft-versus-host disease prophylaxis was uniform with posttransplant cyclophosphamide, a calcineurin inhibitor, and mycophenolate mofetil. The primary end point was disease-free survival. Cox regression models were built to study the effect of conditioning regimen intensity on transplant outcomes. For patients aged 18 to 54 years, disease-free survival was lower (hazard ratio [HR], 1.34; 42% vs 51%; P = .007) and relapse was higher (HR, 1.51; 44% vs 33%; P = .001) with a reduced-intensity regimen compared with a myeloablative regimen. Nonrelapse mortality did not differ according to regimen intensity. For patients aged 55 to 70 years, disease-free survival (HR, 0.97; 37% vs 43%; P = .83) and relapse (HR, 1.32; 42% vs 31%; P = .11) did not differ according to regimen intensity. Nonrelapse mortality was lower with reduced-intensity regimens (HR, 0.64; 20% vs 31%; P = .02). Myeloablative regimens are preferred for AML, ALL, and MDS; reduced-intensity regimens should be reserved for those unable to tolerate myeloablation.

Early precursor T-cell acute lymphoblastic leukemia: current paradigms and evolving concepts

Early precursor T cell-acute lymphoblastic leukemia (ETP-ALL) is a rare entity characterized by chemo-resistance and a paucity of data regarding optimal management. We review here the literature regarding the management of ETP-ALL and focus on the recent, emerging data, regarding the potential role of molecularly targeted approaches with a focus on venetoclax.

Recent Advances in the Management of Acute Lymphoblastic Leukaemia

OPINION STATEMENT

The last few years have seen unprecedented advances in treatment options for patients diagnosed with acute lymphoblastic leukaemia (ALL) in adulthood. New targeted drug therapies have been shown in randomised trials to offer significant survival improvements above standard-of-care (SoC) for relapsed disease, whilst being relatively well tolerated. Chimeric antigen receptor T cell therapy (CAR-T) has offered spectacular promise amongst the young adult population, with the possibility of cure for refractory disease. It has reversed the paradigm that transplant is the only curative option at relapse. Data is awaited regarding its effectiveness in the older adult population. Nelarabine represents an advance, but there remains a pressing need to develop new therapies with efficacy against T-ALL, especially in the relapse setting.Outcomes for younger adults have improved with the adoption of paediatric-like regimens, with a focus on dose intensity and heavy use of pegylated asparaginase. Defining who falls into the "young adult" category and would benefit from this approach remains a controversial area. In elderly patients with ALL, the introduction of tyrosine kinase inhibitors (TKIs) and reduction in standard chemotherapy intensity (especially for those with Philadelphia-positive disease) have significantly reduced treatment-associated mortality and resulted in durable remissions with good quality of life.Bone marrow transplantation remains a key therapy in adult ALL, and is still the treatment of choice for relapsed disease. The mortality associated with a myeloablative approach can be substantially lowered by reduced intensity conditioning, without an apparently significant reduction in efficacy.

Curing Ph+ ALL: assessing the relative contributions of chemotherapy, TKIs, and allogeneic stem cell transplant

The understanding and treatment of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia have changed rapidly in the past 10 years. The outcome is equally as good as for Ph- disease, and with targeted tyrosine kinase inhibitor therapies in addition to chemotherapy, the novel immunotherapy approaches, and the extension of allogeneic hematopoietic stem cell transplant (allo-HCT) to older individuals, there is the potential to exceed this outcome. There is particular interest in reducing chemotherapy exposure and considering for whom allo-HCT can be avoided. However, the patient population that can help test these options in clinical trials is limited in number, and the available evidence is often derived from single-arm studies. This paper summarizes outcomes achieved with recent approaches to de novo Ph+ acute lymphoblastic leukemia in the postimatinib era and helps integrate all the available information to assist the reader to make informed choices for patients in an increasingly complex field.

Haploidentical Stem Cell Transplantation With Posttransplant Cyclophosphamide Therapy vs Other Donor Transplantations in Adults With Hematologic Cancers: A Systematic Review and Meta-analysis

Importance

Use of haploidentical (HAPLO) stem cell transplantation with posttransplant cyclophosphamide is rapidly increasing in adults with hematologic cancers. However, its specific role compared with other transplant strategies has yet to be identified.

Objective

To synthesize the existing evidence regarding outcomes of stem cell transplantations comparing HAPLO stem cell transplantation and posttransplant cyclophosphamide therapy with transplantations from matched related donors (MRDs), matched unrelated donors (MUDs), or mismatched unrelated donors (MMUDs).

Data Sources

PubMed, Cochrane Library, ClinicalTrials.gov, and meeting abstracts were searched for the key words haploidentical and cyclophosphamide from inception through March 1, 2019.

Study Selection

Studies comparing HAPLO stem cell transplantation and posttransplant cyclophosphamide therapy with transplantations from other donors in adults with hematologic cancers were eligible for meta-analysis.

Data Extraction and Synthesis

Pooled odds ratios (ORs) and 95% CIs were calculated using a random-effects model.

Main Outcomes and Measures

Main outcomes were all-cause mortality, nonrelapse mortality, and relapse.

Results

A total of 30 studies including 22 974 participants were analyzed. HAPLO stem cell transplantation with posttransplant cyclophosphamide therapy was associated with increased all-cause mortality compared with MRDs (OR, 1.17; 95% CI, 1.05-1.30), similar all-cause mortality compared with MUDs (OR, 1.06; 95% CI, 0.96-1.18), and reduced all-cause mortality compared with MMUDs (OR, 0.75; 95% CI, 0.61-0.92). Regarding nonrelapse mortality, HAPLO stem cell transplantation with posttransplant cyclophosphamide was associated with worse outcomes compared with MRDs (OR, 1.20; 95% CI, 1.04-1.40) but better outcomes compared with MUDs (OR, 0.75; 95% CI, 0.61-0.92) and MMUDs (OR, 0.51; 95% CI, 0.25-1.02). In terms of relapse, HAPLO stem cell transplantation with posttransplant cyclophosphamide was associated with similar outcome compared with MRDs (OR, 1.01; 95% CI, 0.86-1.17) and MMUDs (OR, 1.06; 95% CI, 0.77-1.47) but showed increased relapse compared with MUDs (OR, 1.20; 95% CI, 1.03-1.40).

Conclusions and Relevance

Results of this meta-analysis suggest that MRDs, if available, remain the optimal donors regarding mortality and HAPLO stem cell transplantation with posttransplant cyclophosphamide may be preferred over MMUDs. Prospective comparisons with MUDs are needed.

Increased CD83 expression of CD34-positive monocytes in donors during peripheral blood stem cell mobilization in humans

CD34-positive monocytes (CD34+mono) have recently been identified in grafts mobilized by granulocyte-colony stimulating factor. We analyzed transplant outcomes of 73 patients whose donor's peripheral blood cells were cryopreserved during mobilization. CD34+mono was detected more frequently in male donors (67% vs. 40%, P = 0.03), while the detection of CD34+mono in donors was not associated with the patient background. Although there was no significant difference in overall survival in the whole cohort, the detection of CD34+mono in donors were significantly associated with a decreased risk of non-relapse mortality (HR 0.23, P = 0.035). Fatal infectious events tended to be less frequent in donors with CD34+mono. Gene expression profile analyses of CD34+mono in humans revealed that the expressions of pro-inflammatory cytokines like IL6, CCL3, IL8, VEGFA, and IL1A were elevated in CD34+mono, and those cytokines were enriched in the immune response, especially against infectious pathogens in the gene ontology analyses. In addition, the expression of CD83 was specifically increased in CD34+mono. It might play a role of antigen presentation in the immune network, leading in a clinical benefit against infections. Further investigations will be required to confirm the biological functions and clinical roles of CD34+mono in transplantation.

Myeloablative vs reduced-intensity conditioning allogeneic hematopoietic cell transplantation for chronic myeloid leukemia

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment of chronic myeloid leukemia (CML). Optimal conditioning intensity for allo-HCT for CML in the era of tyrosine kinase inhibitors (TKIs) is unknown. Using the Center for International Blood and Marrow Transplant Research database, we sought to determine whether reduced-intensity/nonmyeloablative conditioning (RIC) allo-HCT and myeloablative conditioning (MAC) result in similar outcomes in CML patients. We evaluated 1395 CML allo-HCT recipients between the ages of 18 and 60 years. The disease status at transplant was divided into the following categories: chronic phase 1, chronic phase 2 or greater, and accelerated phase. Patients in blast phase at transplant and alternative donor transplants were excluded. The primary outcome was overall survival (OS) after allo-HCT. MAC (n = 1204) and RIC allo-HCT recipients (n = 191) from 2007 to 2014 were included. Patient, disease, and transplantation characteristics were similar, with a few exceptions. Multivariable analysis showed no significant difference in OS between MAC and RIC groups. In addition, leukemia-free survival and nonrelapse mortality did not differ significantly between the 2 groups. Compared with MAC, the RIC group had a higher risk of early relapse after allo-HCT (hazard ratio [HR], 1.85; P = .001). The cumulative incidence of chronic graft-versus-host disease (cGVHD) was lower with RIC than with MAC (HR, 0.77; P = .02). RIC provides similar survival and lower cGVHD compared with MAC and therefore may be a reasonable alternative to MAC for CML patients in the TKI era.

Hematopoietic Cell Transplantation in the Treatment of Adult Acute Lymphoblastic Leukemia: Updated 2019 Evidence-Based Review from the American Society for Transplantation and Cellular Therapy

The role of hematopoietic cell transplantation (HCT) in adults with acute lymphoblastic leukemia (ALL) is reviewed and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the recommendations. A panel of ALL experts developed consensus on the treatment recommendations based on the evidence. Allogeneic HCT offers a survival benefit in selected patients with ALL, and this review summarizes the standard indications as well as the areas of controversy. There is now greater experience with pediatric-inspired chemotherapy regimens that has transformed upfront therapy for adult ALL, resulting in higher remission rates and overall survival. This in turn has increased the equipoise around decision making for ALL in first complete remission (CR1) when there is no measurable residual disease (MRD) at the end of induction and/or consolidation. Randomized studies are needed for adults with ALL to compare allogeneic HCT in CR1 with pediatric-inspired chemotherapy alone. Indications for transplantation in the evolving landscape of MRD assessments and novel targeted and immune therapeutics remain important areas of investigation.

Allogeneic stem cell transplantation in the era of novel therapies for acute lymphoblastic leukaemia

Immunotherapy is changing the treatment of acute lymphoblastic leukaemia (ALL) in adults and children. However, regardless of these new therapies, allogeneic hematopoietic cell transplantation (allo-HCT) still play a key role in the treatment of ALL, although it is uncertain how these new therapies will impact on the transplant procedure and indications. This article reviews the indications of allo-HCT for children and adults diagnosed with ALL, the different sources and conditioning regimens for transplantation as well as the role of measurable residual diseases pre- and post-HCT in the era of the new therapies for ALL.

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.

Related donor transplants: has posttransplantation cyclophosphamide nullified the detrimental effect of HLA mismatch?

We sought to identify whether posttransplantation cyclophosphamide (PT-Cy) reduces or eliminates the detrimental impact of HLA mismatching on outcomes of HLA-haploidentical related donor transplantation for acute leukemia. Data from 2143 donor-recipient pairs (n = 218 haploidentical sibling; n = 218 offspring; n = 1707 HLA-matched sibling) with acute myeloid or lymphoblastic leukemia were studied. All received a calcineurin inhibitor for graft-versus-host disease (GVHD) prophylaxis while high-dose PT-Cy was also given to recipients of haploidentical transplant. Patient age correlated with donor-recipient relationship: haploidentical siblings donated to patients aged 18 to 54 years whereas offspring donated to patients aged 55 to 76 years. Therefore, transplant outcomes were examined separately in the 2 patient age groups. In patients aged 18 to 54 years, there were no significant differences in outcomes except chronic GVHD, which was lower after haploidentical sibling compared to HLA-matched sibling transplant (hazard ratio [HR], 0.63; P < .001). In patients aged 55 to 76 years, despite lower chronic GVHD (HR, 0.42; P < .001), graft failure (14% vs 6%; P = .003), nonrelapse mortality (HR, 1.48; P = .02), and overall mortality (HR, 1.32; P = .003) were higher after transplant from offspring compared with an HLA-matched sibling. These data demonstrate a superior outcome in older recipients when using an HLA-matched sibling instead of offspring, although there were differences in transplant platforms (GVHD prophylaxis and graft type) between the 2 groups. Validation of these findings requires a prospective randomized trial wherein the transplant platforms can be closely matched.

Factors associated with durable EFS in adult B-cell ALL patients achieving MRD-negative CR after CD19 CAR T-cell therapy

Autologous T cells engineered to express a CD19-specific chimeric antigen receptor (CAR) have produced impressive minimal residual disease-negative (MRD-negative) complete remission (CR) rates in patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, the factors associated with durable remissions after CAR T-cell therapy have not been fully elucidated. We studied patients with relapsed/refractory B-ALL enrolled in a phase 1/2 clinical trial evaluating lymphodepletion chemotherapy followed by CD19 CAR T-cell therapy at our institution. Forty-five (85%) of 53 patients who received CD19 CAR T-cell therapy and were evaluable for response achieved MRD-negative CR by high-resolution flow cytometry. With a median follow-up of 30.9 months, event-free survival (EFS) and overall survival (OS) were significantly better in the patients who achieved MRD-negative CR compared with those who did not (median EFS, 7.6 vs 0.8 months; P < .0001; median OS, 20.0 vs 5.0 months; P = .014). In patients who achieved MRD-negative CR by flow cytometry, absence of the index malignant clone by IGH deep sequencing was associated with better EFS (P = .034). Stepwise multivariable modeling in patients achieving MRD-negative CR showed that lower prelymphodepletion lactate dehydrogenase concentration (hazard ratio [HR], 1.38 per 100 U/L increment increase), higher prelymphodepletion platelet count (HR, 0.74 per 50 000/μL increment increase), incorporation of fludarabine into the lymphodepletion regimen (HR, 0.25), and allogeneic hematopoietic cell transplantation (HCT) after CAR T-cell therapy (HR, 0.39) were associated with better EFS. These data allow identification of patients at higher risk of relapse after CAR T-cell immunotherapy who might benefit from consolidation strategies such as allogeneic HCT. This trial was registered at www.clinicaltrials.gov as #NCT01865617.

Recent Advances in the Biology and Treatment of T Cell Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

This article provides an overview of the current knowledge regarding the biology and treatment of T cell acute lymphoblastic leukemia (T-ALL) and highlights the most recent findings in this field over the past 5 years.

RECENT FINDINGS

Remarkable progress has been made in the genomic landscape of T-ALL over the past few years. The discovery of activating mutations of NOTCH1 and FBXW7 in a majority of patients has been a seminal observation, with several early phase clinical trials currently exploring these as potential therapeutic targets. Characterization of early T cell precursor ALL, incorporation of minimal residual disease assessment into therapeutic protocols, and use of pediatric-intensive regimens along with judicious use of allogeneic HCT have significantly improved risk stratification and treatment outcomes. Improved risk stratification and the use of novel targeted therapies based on recent genomic discoveries are expected to change the therapeutic landscape of T-ALL and hopefully improve the outcomes of this historically poor prognosis disease.

Fludarabine with a higher versus lower dose of myeloablative timed-sequential busulfan in older patients and patients with comorbidities: an open-label, non-stratified, randomised phase 2 trial

BACKGROUND

Haemopoietic stem-cell transplantation (HCT) conditioning regimens that can reduce risk of relapse without increasing non-relapse mortality are needed. We aimed to test the safety of timed-sequential delivery of low-dose versus high-dose myeloablative busulfan in older patients and patients with comorbidities.

METHODS

This non-stratified, open-label, randomised phase 2 trial was done at The University of Texas MD Anderson Cancer Center (Houston, TX, USA). Patients with haematological cancers aged between 5 and 75 years were eligible to participate in the study. Patients who had HIV or uncontrollable infections were excluded. Eligible patients were randomly assigned (1:1 by a computer-generated programme in block sizes of four) to receive a total intravenous busulfan dose to achieve an area under the curve of 16 000 μmol/min (16K group) or 20 000 μmol/min (20K group) on the basis of pharmacokinetic analysis, plus intravenous fludarabine 40 mg/m² for 4 days. The investigators and the research nurses were masked to the block size to conceal allocation. The primary outcome was day 100 non-relapse mortality. All analyses were by modified intention to treat, including only patients who received at least one dose of the study drug. No interim analyses were planned and accrual is complete. This study is registered with ClinicalTrials.gov, number NCT01572662.

FINDINGS

Between April 18, 2012, and Dec 9, 2015, 98 patients were enrolled. 49 patients were randomly assigned to the 16K group and 49 to the 20K group, one of which was removed from the study before starting the intervention. Median age was 60 years (IQR 54-67). 50 (52%) patients had an HCT-specific comorbidity index score of 3 or more, and 41 (42%) had a high or very high Disease Risk Index score. Day 100 non-relapse mortality was 4% (95% CI 0-10) in the 16K group and 6% (0-13) in the 20K group (p=0·65). Infection was the most common grade 3-5 toxicity in both the 20K group (25 [52%] of 48 patients) and the 16K group (24 [49%] of 49 participants). Mucositis (nine [19%] of 48 patients vs three [6%] of 49 patients), idiopathic pneumonia syndrome (nine [19%] of 48 patients vs two [4%] of 49 patients), and culture-negative neutropenic fever (16 [33%] of 48 patients vs eight [16%] of 49 patients) were more common in the 20K group than in the 16K group.

INTERPRETATION

Myeloablative doses of busulfan administered in a timed-sequential manner with fludarabine is associated with low non-relapse mortality in older patients and patients with comorbidities. Additional studies are required to show whether this approach can reduce the risk of relapse.

FUNDING

Cancer Center Support Grant (US National Cancer Institute, National Institutes of Health).

Minimal residual disease-based long-term efficacy of reduced-intensity conditioning versus myeloablative conditioning for adult Philadelphia-positive acute lymphoblastic leukemia

BACKGROUND

The sensitivity of Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) to reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT) versus myeloablative conditioning (MAC) allogeneic HCT by minimal residual disease (MRD) kinetics is not well established.

METHODS

This study compared long-term outcomes based on MRD kinetics for 79 patients with RIC transplants and 116 patients with MAC transplants in first complete remission (CR1) after tyrosine kinase inhibitor-based chemotherapy (median follow-up, 67.1 months). MRD monitoring was centrally evaluated by real-time quantitative polymerase chain reaction for all patients.

RESULTS

RIC showed a cumulative incidence of relapse (CIR; 30.6% vs 31.7%), nonrelapse mortality (17.5% vs 14.9%), disease-free survival (DFS; 51.9% vs 53.4%), and overall survival (61.1% vs 61.4%) comparable to those associated with MAC. In all MRD kinetics-based subgroups, no differences in CIR (early complete molecular response [CMR], 19.3% vs 4.8%; early major molecular response [MMR], 17.0% vs 26.8%; late CMR, 20.0% vs 14.3%; late MMR, 28.3% vs 31.0%; poor molecular response [PMR], 57.9% vs 62.4%) or DFS (early CMR, 71.6% vs 76.2%; early MMR, 66.9% vs 52.1%; late CMR, 50.0% vs 64.3%; late MMR, 50.7% vs 53.7%; PMR, 31.6% vs 34.1%) were observed between RIC and MAC. In a multivariate analysis, the conditioning intensity had no significant impact on transplantation outcomes.

CONCLUSIONS

RIC is a valid alternative choice for long-term disease control and is worthy of further investigation in prospective trials for adult Ph-positive ALL in CR1.

Chemoimmunotherapy with inotuzumab ozogamicin combined with mini-hyper-CVD, with or without blinatumomab, is highly effective in patients with Philadelphia chromosome-negative acute lymphoblastic leukemia in first salvage

BACKGROUND

The outcomes of patients with relapsed or refractory (R-R) acute lymphoblastic leukemia (ALL) are poor. Inotuzumab ozogamicin and blinatumomab have single-agent activity in R-R ALL. Their addition to low-intensity chemotherapy may further improve the outcomes of patients with ALL in their first relapse.

METHODS

The chemotherapy was lower in intensity than conventional hyperfractionated cyclophosphamide, vincristine, adriamycin, and dexamethasone and was called mini-hyperfractionated cyclophosphamide, vincristine, and dexamethasone (or mini-HCVD). Inotuzumab was given on day 3 of each of the first 4 cycles at 1.8 to 1.3 mg/m² for cycle 1, and this was followed by 1.3 to 1.0 mg/m² for subsequent cycles. From patient 39 onward, the inotuzumab dose was reduced and fractionated into weekly doses (0.6 and 0.3 mg/m² during cycle 1 and 0.3 and 0.3 mg/m² during subsequent cycles), and blinatumomab was administered for up to 4 cycles after inotuzumab therapy.

RESULTS

Forty-eight patients with Philadelphia chromosome-negative ALL with a median age of 39 years were treated during their first relapse. Overall, 44 patients (92%) responded, with 35 of them (73%) achieving a complete response. The overall minimal residual disease negativity rate among the responders was 93%. Twenty-four patients (50%) underwent allogeneic stem cell transplantation (ASCT). Veno-occlusive disease of any grade occurred in 5 patients (10%). With a median follow-up of 31 months, the median progression-free survival (PFS) and the median overall survival (OS) were 11 and 25 months, respectively. The 2-year PFS and OS rates were 42% and 54%, respectively. Of the 24 patients (50%) who underwent ASCT, 14 patients were alive at the last follow-up (13 [54%] in remission). Of the remaining 20 responding patients who did not undergo subsequent ASCT, 6 (30%) remained in remission at the last follow-up. According to propensity score matching, the combination of mini-HCVD and inotuzumab with or without blinatumomab conferred better outcomes than intensive salvage chemotherapy or inotuzumab alone.

CONCLUSIONS

The combination of inotuzumab and low-intensity mini-HCVD chemotherapy with or without blinatumomab shows encouraging results in patients with ALL in first salvage.

Elderly acute lymphoblastic leukemia: a Mayo Clinic study of 124 patients

Poor outcomes in elderly acute lymphoblastic leukemia (ALL) are well recognized, but the contributors are ill-defined. We characterized 124 patients ≥60 years old at our institution. The majority (n = 102, 82%) were treated with intensive chemotherapy. Of these, 8/102 (8%) died within the first 100 days; 92/102 (90%) achieved complete remission (CR/CRi). Only 31/124 (25%) patients underwent allogeneic hematopoietic stem cell transplantation. The median overall survival (OS) for the entire cohort was 19.8 months. In a multivariate analysis, ECOG performance status ≥2, high white blood cell count, and high lactate dehydrogenase (at time of diagnosis) negatively influenced OS (p<.01). In a subgroup analysis of the intensive treatment group, BCR-ABL1+ patients had markedly better OS (hazard ratio 0.3, 95% CI 0.1-0.7; p<.01). In summary, despite few early deaths and a high CR/CRi rate, elderly ALL continues to have a poor prognosis, underscoring the need for more effective therapies.

Reduced Intensity Conditioning Allogeneic Hematopoietic Stem Cell Transplantation for Acute Lymphoblastic Leukemia; Current Evidence, and Improving Outcomes Going Forward

PURPOSE OF REVIEW

Outcomes for older adults with acute lymphoblastic leukemia (ALL) remain poor, and allogeneic hematopoietic stem cell transplant (HSCT) remains a potentially curative modality. However, benefits are offset by high rates of non-relapse mortality (NRM) in patients undergoing myeloablative conditioning (MAC) regimens. Reduced intensity conditioning (RIC) regimens can extend this therapy to adults who are unfit for MAC, although at the cost of higher relapse rates. In this review, we discuss evidence to support the usage of RIC regimens, controversies, and potential strategies to improve transplant outcomes going forward.

RECENT FINDINGS

Several novel therapies have recently been approved for the treatment of relapsed ALL and may play an important role in bridging adults with residual disease to RIC transplant. Assessing response to initial therapy via minimal residual disease (MRD) monitoring may determine which patients will derive the most benefit from allogeneic HSCT. Reduced intensity allogeneic HSCT remains a potentially curative therapy that can be offered to older adults however challenges remain. Going forward, MRD testing and novel therapies may help better select which patients should proceed to transplant and assist in getting those patients to transplant with optimally controlled disease.

Hematopoietic stem cell transplant in adults with acute lymphoblastic leukemia: the present state

INTRODUCTION

Allogeneic hematopoietic stem cell transplant (allo-HSCT) has an important role in management of acute lymphoblastic leukemia (ALL). Proper patient selection is central to ensure optimal outcomes. Areas covered: This review covers various aspects of HSCT in ALL patients, including indications, donor selection, conditioning regimens, and post-transplant management. Expert commentary: Allo-HSCT is important in post-remission management of ALL but proper risk-stratification is a major challenge. Incorporation of minimal residual disease (MRD) and molecular testing will improve patient allocation. Patients receiving pediatric-inspired induction who achieve molecular remission might not need allo-HSCT in first remission. Allo-HSCT should be considered in patients who don't achieve MDR negativity, didn't receive intensive induction, or have high risk cytogenetic and molecular features. Despite improved responses with tyrosine kinase inhibitors (TKIs) in Philadelphia positive (Ph+) ALL, allo-HSCT remains standard. Matched sibling donors are the optimal graft source, but other sources are valid alternatives. There is no single optimal conditioning regimen and retrospective studies found myeloablative and reduced intensity regimens to be comparable. Following allo-HSCT, there is no role for maintenance therapy in Philadelphia-negative ALL. In Ph+ ALL, maintenance TKIs improve outcomes. The integration of targeted and immunotherapies in the peri-transplant period holds potential for improved outcomes.