Different molecular levels of post-induction minimal residual disease may predict hematopoietic stem cell transplantation outcome in adult Philadelphia-negative acute lymphoblastic leukemia

Laboratory validation and clinical utility of next-generation sequencing-based IGH/TCR clonality testing for the monitoring of measurable residual disease in acute lymphoblastic leukaemia: real-world experience at Austin Pathology

Measurable residual disease (MRD) testing is an essential aspect of disease prognostication in acute lymphoblastic leukaemia (ALL) and informs clinical decisions. The depth of MRD clearance is highly relevant and requires assays with sufficient sensitivity. Austin Pathology is one of the few laboratories in Australia currently utilising a fully validated and National Association of Testing Authorities (NATA)-accredited ultrasensitive next-generation sequencing (NGS) platform for MRD monitoring in ALL. This technology is based on the detection of clonal rearrangement of immunoglobulin and T cell receptor genes in leukaemic cells, and is capable of achieving a limit of detection at least one to two logs below that of multiparametric flow cytometry (MFC). In this retrospective analysis, we report a clonotype detection rate of up to 85.7% at diagnosis, and a concordance rate of 78.7% in MRD results between NGS and MFC. Of the discordant samples, nearly all were NGS+/MFC-, highlighting the superior sensitivity of NGS. The enhanced sensitivity is clinically relevant, as discordant MRD results often heralded fulminant relapse, and therefore offer clinicians additional lead time and a window of opportunity to initiate pre-emptive therapy. Notwithstanding a small and heterogeneous cohort, our real-world survival data indicate an intermediate relapse risk for NGS+/MFC- patients. In light of recent approval of Medicare rebatable ALL MRD testing, we discuss how NGS can complement other techniques such as MFC in personalising management strategies. We recommend routine clonality testing by NGS at diagnosis and use a multi-modality approach for subsequent MRD monitoring.

Management of ALL in adults: 2024 ELN recommendations from a European expert panel

ABSTRACT

Experts from the European Leukemia Net (ELN) working group for adult acute lymphoblastic leukemia have identified an unmet need for guidance regarding management of adult acute lymphoblastic leukemia (ALL) from diagnosis to aftercare. The group has previously summarized their recommendations regarding diagnostic approaches, prognostic factors, and assessment of ALL. The current recommendation summarizes clinical management. It covers treatment approaches, including the use of new immunotherapies, application of minimal residual disease for treatment decisions, management of specific subgroups, and challenging treatment situations as well as late effects and supportive care. The recommendation provides guidance for physicians caring for adult patients with ALL which has to be complemented by regional expertise preferably provided by national academic study groups.

Genetic alterations and MRD refine risk assessment for KMT2A-rearranged B-cell precursor ALL in adults: a GRAALL study

KMT2A-rearranged (KMT2A-r) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is widely recognized as a high-risk leukemia in both children and adults. However, there is a paucity of data on adults treated in recent protocols, and the optimal treatment strategy for these patients is still a matter of debate. In this study, we set out to refine the prognosis of adult KMT2A-r BCP-ALL treated with modern chemotherapy regimen and investigate the prognostic impact of comutations and minimal residual disease (MRD). Of 1091 adult patients with Philadelphia-negative BCP-ALL enrolled in 3 consecutive trials from the Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL), 141 (12.9%) had KMT2A-r, with 5-year cumulative incidence of relapse (CIR) and overall survival (OS) rates of 40.7% and 53.3%, respectively. Molecular profiling highlighted a low mutational burden in this subtype, reminiscent of infant BCP-ALL. However, the presence of TP53 and/or IKZF1 alterations defined a subset of patients with significantly poorer CIR (69.3% vs 36.2%; P = .001) and OS (28.1% vs 60.7%; P = .006) rates. Next, we analyzed the prognostic implication of MRD measured after induction and first consolidation, using both immunoglobulin (IG) or T-cell receptor (TR) gene rearrangements and KMT2A genomic fusion as markers. In approximately one-third of patients, IG/TR rearrangements were absent or displayed clonal evolution during the disease course, compromising MRD monitoring. In contrast, KMT2A-based MRD was highly reliable and strongly associated with outcome, with early good responders having an excellent outcome (3-year CIR, 7.1%; OS, 92.9%). Altogether, our study reveals striking heterogeneity in outcomes within adults with KMT2A-r BCP-ALL and provides new biomarkers to guide risk-based therapeutic stratification.

The evolution of acute lymphoblastic leukemia research and therapy at MD Anderson over four decades

Progress in the research and therapy of adult acute lymphoblastic leukemia (ALL) is accelerating. This analysis summarizes the data derived from the clinical trials conducted at MD Anderson between 1985 and 2022 across ALL subtypes. In Philadelphia chromosome-positive ALL, the addition of BCR::ABL1 tyrosine kinase inhibitors (TKIs) to intensive chemotherapy since 2000, improved outcomes. More recently, a chemotherapy-free regimen with blinatumomab and ponatinib resulted in a complete molecular remission rate of 85% and an estimated 3-year survival rate of 90%, potentially reducing the role of, and need for allogeneic stem cell transplantation (SCT) in remission. In younger patients with pre-B Philadelphia chromosome-negative ALL, the integration of blinatumomab and inotuzumab into the frontline therapy has improved the estimated 3-year survival rate to 85% across all risk categories. Our future strategy is to evaluate the early integration of both immunotherapy agents, inotuzumab and blinatumomab, with low-dose chemotherapy (dose-dense mini-Hyper-CVD-inotuzumab-blinatumomab) into the frontline setting followed by CAR T cells consolidation in high-risk patients, without any further maintenance therapy. In older patients, using less intensive chemotherapy (mini-Hyper-CVD) in combination with inotuzumab and blinatumomab has improved the 5-year survival rate to 50%. Among patients ≥ 65-70 years, the mortality in complete remission (CR) is still high and is multifactorial (old age, death in CR with infections, development of myelodysplastic syndrome or acute myeloid leukemia). A chemotherapy-free regimen with inotuzumab and blinatumomab is being investigated. The assessment of measurable residual disease (MRD) by next-generation sequencing (NGS) is superior to conventional assays, with early MRD negativity by NGS being associated with the best survival. We anticipate that the future therapy in B-ALL will involve less intensive and shorter chemotherapy regimens in combination with agents targeting CD19 (blinatumomab), CD20, and CD22 (inotuzumab). The optimal timing and use of CAR T cells therapy may be in the setting of minimal disease, and future trials will assess the role of CAR T cells as a consolidation among high-risk patients to replace allogeneic SCT. In summary, the management of ALL has witnessed significant progress during the past four decades. Novel combination regimens including newer-generation BCR::ABL1 TKIs and novel antibodies are questioning the need and duration of intensive chemotherapy and allogeneic SCT.

MRD in ALL: Optimization and Innovations

PURPOSE OF REVIEW

Measurable residual disease (MRD) is an important monitoring parameter that can help predict survival outcomes in acute lymphoblastic leukemia (ALL). Identifying patients with MRD has the potential to decrease the risk of relapse with the initiation of early salvage therapy and to help guide decision making regarding allogeneic hematopoietic cell transplantation. In this review, we discuss MRD in ALL, focusing on advantages and limitations between MRD testing techniques and how to monitor MRD in specific patient populations.

RECENT FINDINGS

MRD has traditionally been measured through bone marrow samples, but more data for evaluation of MRD via peripheral blood is emerging. Current and developmental testing strategies for MRD include multiparametric flow cytometry (MFC), next-generation sequencing (NGS), quantitative polymerase chain reaction (qPCR), and ClonoSeq. Novel therapies are incorporating MRD as an outcome measure to demonstrate efficacy, including blinatumomab, inotuzumab ozogamicin, and chimeric antigen receptor T (CAR-T) cell therapy. Understanding how to incorporate MRD testing into the management of ALL could improve patient outcomes and predict efficacy of new therapy options.

Controversies in the Treatment of Adolescents and Young Adults with Philadelphia Chromosome-Negative B-Cell Acute Lymphoblastic Leukemia

PURPOSE OF THE REVIEW

The incidence of acute lymphoblastic leukemia (ALL) has been increasing steadily in the adolescent and young adult (AYA) population. In this review article focused on the management of AYAs with Philadelphia chromosome-negative (Ph-) B-ALL, we examine topics of clinical interest and identify areas of controversy in need of further investigation.

RECENT FINDINGS

We explore four areas of active investigation: pediatric-inspired front-line treatment regimens, the optimal time of measurable residual disease (MRD) assessment, the role of hematopoietic stem cell transplant and the optimal salvage therapy for relapsed/refractory B-ALL in AYAs. There has been rapid advancement in the management of ALL in the AYA patient population, which has resulted in improved outcomes. We must build on the successes by continuing to promote multi-center innovative clinical research with clinical trial populations reflecting the AYA ALL patient spectrum. The incorporation of novel targeted immunotherapy into front-line treatment will be transformative and redefine treatment paradigms in the coming years.

Prognostic value of low-level MRD in adult acute lymphoblastic leukemia detected by low- and high-throughput methods

Adult patients with acute lymphoblastic leukemia with low MRD positivity at week 16 form an intermediate-risk group.

NGS improves the risk assignment of patients with MolNE MRD.

Persistence of minimal residual disease (MRD) after induction/consolidation therapy in acute lymphoblastic leukemia is the leading cause of relapse. The GMALL 07/2003 study used MRD detection by real-time quantitative polymerase chain reaction of clonal immune gene rearrangements with 1 × 10⁻⁴ as discriminating cutoff: levels ≥1 × 10⁻⁴ define molecular failure and MRD-negativity with an assay sensitivity of at least 1 × 10⁻⁴ defining complete molecular response. The clinical relevance of MRD results not fitting into these categories is unclear and termed “molecular not evaluable” (MolNE) toward MRD-based treatment decisions. Within the GMALL 07/03 study, 1019 consecutive bone marrow samples after first consolidation were evaluated for MRD. Patients with complete molecular response had significantly better outcome (5-year overall survival [OS] = 85% ± 2%, n = 603; 5-year disease-free survival [DFS] = 73% ± 2%, n = 599) compared with patients with molecular failure (5-year OS = 40% ± 3%, n = 238; 5-year DFS = 29% ± 3%, n = 208), with patients with MolNE in between (5-year OS = 66% ± 4%; 5-year DFS = 52% ± 4%, n = 178). Of MolNE samples reanalyzed using next-generation sequencing (NGS), patients with undetectable NGS-MRD (n = 44; 5-year OS = 88% ± 5%, 5-year DFS = 70% ± 7%) had significantly better outcome than those with positive NGS-MRD (n = 42; 5-year OS = 37% ± 8%; 5-year DFS = 33% ± 8%). MolNE MRD results not just are borderline values with questionable relevance but also form an intermediate-risk group, assignment of which can be further improved by NGS.

MRD in adult Ph/BCR-ABL-negative ALL: how best to eradicate?

Evaluation of minimal residual disease (MRD) during first-line treatment and after salvage therapy is part of the standard management of acute lymphoblastic leukemia (ALL). Persistent or recurrent MRD is one of the most relevant prognostic factors and identifies a group of patients with resistance to standard chemotherapy. These patients have a high risk of relapse despite continued first-line therapy. Although stem cell transplantation (SCT) is an appropriate strategy, patients with high MRD show an increased relapse rate even after SCT. Approximately one-quarter of adult ALL patients develop an MRD failure, defined as MRD above 0.01% after standard induction and consolidation. The best time point and level of MRD for treatment modification are matters of debate. In order to eradicate MRD and thereby improve chances for a cure, new targeted compounds with different mechanisms of action compared to chemotherapy are being utilized. These compounds include monoclonal antibodies, chimeric antigen receptor T cells, and molecular targeted compounds. Essential factors for decision-making, available compounds, and follow-up therapies are discussed.

Recent Advances in Managing Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is characterized by chromosomal translocations and somatic mutations that lead to leukemogenesis. The incorporation of pediatric-type regimens has improved survival in young adults, and the incorporation of tyrosine kinase inhibitors for patients with Philadelphia chromosome-positive disease has led to further improvements in outcomes. However, older patients often have poor-risk biology and reduced tolerance to chemotherapy, leading to lower remission rates and overall survival. Regardless of age, patients with relapsed or refractory ALL have extremely poor outcomes. The advent of next-generation sequencing has facilitated the revolution in understanding the genetics of ALL. New genetic risk stratification together with the ability to measure minimal residual disease, leukemic blasts left behind after cytotoxic chemotherapy, has led to better tools to guide postremission approaches-that is, consolidation chemotherapy or allogeneic stem cell transplantation. In this article, we discuss the evolving and complex genetic landscape of ALL and the emerging therapeutic options for patients with relapsed/refractory ALL and older patients with ALL.

Impact of Novel Targeted Therapies and Cytogenetic Risk Groups on Outcome After Allogeneic Transplantation for Adult ALL

Novel high-risk groups have recently been identified in adult acute lymphoblastic leukemia (ALL), including Philadelphia-like, therapy-related, and measurable residual disease after induction therapy. Furthermore, modern targeted therapies have recently been incorporated into ALL management; rituximab for CD20-positive and blinatumomab for measurable residual disease after induction therapy or relapsed or refractory disease. Allogeneic hematopoietic cell transplantation (allo-HCT) is recommended as consolidation therapy for high-risk ALL; however, its relative benefit for these high-risk groups and after novel therapies is unclear. We performed an analysis of posttransplantation outcomes in a cohort of 261 consecutive patients who underwent allo-HCT for ALL at the 3-site Mayo Clinic Cancer Center (January 1, 2008-December 31, 2018). With a median (range) follow-up of 22.4 months (0.5-135.0), the 100-day and 5-year cumulative incidences of nonrelapse mortality rates were 6.5% and 26.7%, respectively. The 5-year cumulative incidences of relapse and death were 22.6% and 46.2%, respectively. The 1-year estimate of the composite endpoint of graft-versus-host disease/relapse-free survival was 39.3%. We observed no associations of novel high-risk groups or modern targeted therapies with overall survival, nonrelapse mortality, or relapse in multivariable analysis. An increased risk of relapse was observed with T-ALL (hazard ratio, 2.16; 95% confidence interval, 1.14-4.09; P = .02) and hypodiploidy/near-triploidy (hazard ratio, 2.84; 95% confidence interval, 1.06-7.62; P = .04). Our analysis suggests that novel high-risk groups derive a similar benefit from allo-HCT as traditional high-risk adult ALL and that novel targeted therapies do not seem to independently predict for posttransplantation outcomes. It also calls for further exploration of maintenance strategies after Allo-HCT to prevent relapse in high-risk subgroups.

Updated risk-oriented strategy for acute lymphoblastic leukemia in adult patients 18-65 years: NILG ALL 10/07

An updated strategy combining pediatric-based chemotherapy with risk-oriented allogeneic hematopoietic cell transplantation (HCT) was evaluated in Philadelphia chromosome-negative acute lymphoblastic leukemia (Ph- ALL) and compared with a published control series. Following induction-consolidation chemotherapy, responsive patients were assigned to receive maintenance chemotherapy or undergo early HCT according to the risk stratification criteria and minimal residual disease (MRD) status. Of the 203 study patients (median age 41 years, range 17-67), 140/161 with Ph- ALL achieved complete remission (86.9%; 91.6% ≤55 years, P = 0.0002), with complete MRD clearing in 68/109; 55 patients were assigned to maintenance chemotherapy, and 85 to HCT due to very high-risk characteristics (hyperleukocytosis, adverse genetics, early/mature T-precursor ALL, and MRD persistence). The 5-year relapse incidence was 36%, and the treatment-related mortality rate was 18%. Median overall and relapse-free survival were 7.4 and 6.2 years, with rates of 54 and 53% at 5 years, respectively, which were significantly better than those obtained with the historical protocol (P = 0.001 and P = 0.005, respectively), without significant differences between maintenance and HCT cohorts. In prognostic analysis, MRD negativity and age ≤55 years were the most favorable independent prognostic factors. A reduction in treatment toxicity and further improvements in the risk definitions and risk-oriented design are the focuses of this ongoing research.

Monitoring MRD in ALL: Methodologies, technical aspects and optimal time points for measurement

The accurate determination of minimal or measurable residual disease (MRD) during the early months of therapy in acute lymphoblastic leukemia is well established as the most important independent prognostic biomarker, predicting response to combination chemotherapy. Stratification based on MRD maximizes treatment effectiveness while minimizing adverse effects. Allele-specific real-time quantitative PCR of clone-defining immunoglobin/T-cell receptor gene rearrangements in the patients' leukemic clones and/or multiparametric flow cytometric tracking of leukemia-associated immunophenotypes are considered standard of care. Following recent advances in high throughput sequencing (HTS; next generation sequencing), much attention has been devoted to the development of HTS-based MRD assays, which can increase sensitivity; theoretically only limited by the number of cells input into the assay. Knowledge of the methods and limitations of each technology, along with awareness of the sensitivity and specificity of MRD at particular treatment time points is important in interpretation of the MRD value. MRD negativity at pre-established protocol-appropriate time points guides continuance with consolidation/maintenance chemotherapy, whereas positivity leads to a change to a biological therapy such as blinatumomab and intensification of therapy to allogeneic stem cell transplant. Positivity after maintenance may herald impending relapse enabling treatment intervention. MRD has been integral to the introduction of novel agents and cellular therapies into clinical trials and standard of care, but the long-term predictive value of MRD on outcome of novel therapies is not yet established. Integration of somatic genetics with MRD may further improve accurate identification of patients with the lowest and highest risk of relapse.

Blinatumomab vs historic standard-of-care treatment for minimal residual disease in adults with B-cell precursor acute lymphoblastic leukaemia

OBJECTIVES

Survival outcomes from a single-arm phase 2 blinatumomab study in patients with minimal residual disease (MRD)-positive B-cell precursor (BCP)-acute lymphoblastic leukaemia (ALL) were compared with those receiving standard of care (SOC) in a historic data set.

METHODS

The primary analysis comprised adult Philadelphia chromosome (Ph)-negative patients in first complete haematologic remission (MRD ≥ 10^-3 ). Relapse-free survival (RFS) and overall survival (OS) were compared between blinatumomab- and SOC-treatment groups. Baseline differences between groups were adjusted by propensity scores.

RESULTS

The primary analysis included 73 and 182 patients from the blinatumomab and historic data sets, respectively. When weighted by age to the blinatumomab-treatment group, median RFS was 7.8 months and median OS was 25.9 months in the SOC-treated group. In the blinatumomab study, median RFS was 35.2 months; median OS was not evaluable. Propensity score weighting achieved balance with seven baseline prognostic factors. With adjustment for haematopoietic stem cell transplantation (HSCT) status, a 50% reduction in risk of relapse or death was observed with blinatumomab vs SOC. Median RFS, unadjusted for HSCT status, was 35.2 months with blinatumomab and 8.3 months with SOC.

CONCLUSIONS

These analyses suggest that blinatumomab improves RFS, and possibly OS, in adults with MRD-positive Ph-negative BCP-ALL vs SOC.

A systematic literature review and meta-analysis of minimal residual disease as a prognostic indicator in adult B-cell acute lymphoblastic leukemia

Minimal (or 'measurable') residual disease in acute lymphoblastic leukemia appears to be a prognostic indicator, with potential value in informing individualized treatment decisions. Complete understanding of the strength of the association between minimal residual disease and long-term outcomes is, however, lacking. A systematic literature review and meta-analysis were performed to elucidate the clinical significance of minimal residual disease with respect to relapse-free survival and overall survival in precursor B-cell acute lymphoblastic leukemia. A total of 23 articles and abstracts, most published between 2012 and 2016, were identified for inclusion in the primary meta-analysis. Typically, patients were in their first complete remission at the time of minimal residual disease assessment; in two studies, all patients were in their second, or later, complete remission. The primary analysis revealed improved relapse-free survival across all studies for patients who achieved minimal residual disease negativity (random effects hazard ratio, 2.34; 95% confidence interval, 1.91-2.86). Improved overall survival for patients who achieved minimal residual disease negativity was also observed (hazard ratio, 2.19; 95% confidence interval, 1.63-2.94). There was no observed difference in the impact of minimal residual disease status in subgroups based on disease stage, minimal residual disease sensitivity threshold level, Philadelphia chromosome status, histological phenotype, risk group, minimal residual disease testing location, minimal residual disease timing after induction, or minimal residual disease detection method. Despite heterogeneity in study design and patient populations between the contributing studies, these data provide a compelling argument for minimal residual disease as a clinical tool for assessing prognosis and guiding treatment decisions in precursor B-cell acute lymphoblastic leukemia.

Minimal Residual Disease in Acute Lymphoblastic Leukemia: Technical and Clinical Advances

Introduction: Acute lymphoblastic leukemia (ALL) is the first neoplasm where the assessment of early response to therapy by minimal residual disease (MRD) monitoring has proven to be a fundamental tool to guide therapeutic choices. The most standardized methods to study MRD in ALL are multi-parametric flow cytometry (MFC) and polymerase chain reaction (PCR) amplification-based methods. Emerging technologies hold the promise to improve MRD detection in ALL patients. Moreover, novel therapies, such as monoclonal antibodies, bispecific T-cell engagers, and chimeric antigen receptor T cells (CART) represent exciting advancements in the management of B-cell precursor (BCP)-ALL.

Aims: Through a review of the literature and in house data, we analyze the current status of MRD assessment in ALL to better understand how some of its limitations could be overcome by emerging molecular technologies. Furthermore, we highlight the future role of MRD monitoring in the context of personalized protocols, taking into account the genetic complexity in ALL.

Results and Conclusions: Molecular rearrangements (gene fusions and immunoglobulin and T-cell receptor-IG/TR gene rearrangements) are widely used as targets to detect residual leukemic cells in ALL patients. The advent of novel techniques, namely next generation flow cytometry (NGF), digital-droplet-PCR (ddPCR), and next generation sequencing (NGS) appear important tools to evaluate MRD in ALL, since they have the potential to overcome the limitations of standard approaches. It is likely that in the forthcoming future these techniques will be incorporated in clinical trials, at least at decisional time points. Finally, the advent of new powerful compounds is further increasing MRD negativity rates, with benefits in long-term survival and a potential reduction of therapy-related toxicities. However, the prognostic relevance in the setting of novel immunotherapies still needs to be evaluated.

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.

Taking a "BiTE out of ALL": blinatumomab approval for MRD-positive ALL

Blinatumomab, a bispecific T-cell engager (BiTE) associated with improved survival in relapsed or refractory acute lymphoblastic leukemia (ALL), was recently approved for treatment of minimal residual disease (MRD). MRD is an important predictor of survival in ALL, and recent studies suggest that achievement of MRD-negativity with blinatumomab improves outcomes in patients with ALL. However, further research is needed to determine how to optimally incorporate blinatumomab, and other novel therapies, into current therapies for ALL.

Minimal residual disease level predicts outcome in adults with Ph-negative B-precursor acute lymphoblastic leukemia

OBJECTIVES

Detectable minimal residual disease (MRD) after therapy for acute lymphoblastic leukemia (ALL) is the strongest predictor of hematologic relapse. This study evaluated outcomes of patients with B-cell precursor ALL with MRD of ≥10^-4 Methods: Study population was from ALL study groups in Europe managed in national study protocols 2000-2014. MRD was measured by polymerase chain reaction or flow cytometry. Patients were age ≥15 years at initial ALL diagnosis. Patients were excluded if exposed to blinatumomab within 18 months of baseline or prior alloHSCT.

RESULTS

Of 272 patients in CR1, baseline MRD was ≥10^-1, 10^-2 to <10^-1, 10^-3 to <10^-2, and 10^-4 to <10^-3 in 15 (6%), 71 (26%), 109 (40%), and 77 (28%) patients, respectively. Median duration of complete remission (DoR) was 18.5 months (95% confidence interval [CI], 11.9-27.2), median relapse-free survival (RFS) was 12.4 months (95% CI, 10.0-19.0) and median overall survival (OS) was 32.5 months (95% CI, 23.6-48.0). Lower baseline MRD level (P ≤ .0003) and white blood cell count <30,000/µL at diagnosis (P ≤ .0053) were strong predictors for better RFS and DoR. Allogeneic hematopoietic stem cell transplantation (alloHSCT) was associated with longer RFS (hazard ratio [HR], 0.59; 95% CI, 0.41-0.84) and DoR (HR, 0.43; 95% CI, 0.29-0.64); the association with OS was not significant (HR, 0.72; 95% CI, 0.50-1.05).

DISCUSSION

In conclusion, RFS, DoR, and OS are relatively short in patients with MRD-positive ALL, particularly at higher MRD levels. AlloHSCT may improve survival but has limitations. Alternative approaches are needed to improve outcomes in MRD-positive ALL.

Blinatumomab, a bispecific B-cell and T-cell engaging antibody, in the treatment of B-cell malignancies

Blinatumomab (Blincyto, Amgen), a bi-specific antibody, is a first-in-class, targeted immunotherapy agent for treatment of B-cell malignancies with a novel mechanism of action which involves in-vivo engagement of the patient's T cells with CD19-expressing tumour cells. Clinical trials have demonstrated its efficacy in relapsed B-cell Acute Lymphoblastic Leukaemia (B-ALL) and B-cell Non-Hodgkin's Lymphoma including in patients who are refractory to chemotherapy. This review summarises the development and design of Blinatumomab, the outcome of clinical studies demonstrating its efficacy and how to manage the administration, practically, including relevant toxicities. We compare and contrast it to other emerging agents for treatment of B-cell malignancies.

Testing for minimal residual disease in adults with acute lymphoblastic leukemia in Europe: a clinician survey

BACKGROUND

In acute lymphoblastic leukemia (ALL), the presence of minimal residual disease (MRD) after induction/consolidation chemotherapy is a strong prognostic factor for subsequent relapse and mortality. Accordingly, European clinical guidelines and protocols recommend testing patients who achieve a complete hematological remission (CR) for MRD for the purpose of risk stratification. The aim of this study was to provide quantitative information regarding real-world clinical practice for MRD testing in five European countries.

METHODS

A web-based survey was conducted in March/April 2017 in France, Germany, Italy, Spain, and the UK. The survey was developed after consultation with specialist clinicians and a review of published literature. Eligible clinicians (20 per country; 23 in Spain) were board-certified in hemato-oncology or hematology, had at least five years' experience in their current role after training, had treated at least two patients with B-cell precursor ALL in the 12 months before the survey or at least five patients in the last five years, and had experience of testing for MRD in clinical practice.

RESULTS

MRD testing is now standard practice in the treatment of adult ALL across the five European countries, with common use of recent treatment protocols which specify testing. Respondents estimated that, among clinicians in their country who conduct MRD testing, 73% of patients in first CR (CR1) and 63% of patients in second or later CR (CR2+) are tested for MRD. The median time point reported as most commonly used for the first MRD test, to establish risk status and to determine a treatment plan was four weeks after the start of induction therapy. The timing and frequency of tests is similar across countries. An average of four or five post-CR1 tests per patient in the 12 months after the first MRD test were reported across countries.

CONCLUSIONS

This comprehensive study of MRD testing patterns shows consistent practice across France, Germany, Italy, Spain, and the UK with respect to the timing and frequency of MRD testing, aligning with use of national protocols. MRD testing is used in clinical practice also in patients who reach CR2 + .

New Approaches to the Management of Adult Acute Lymphoblastic Leukemia

Traditional treatment regimens for adult acute lymphoblastic leukemia, including allogeneic hematopoietic cell transplantation, result in an overall survival of approximately 40%, a figure hardly comparable with the extraordinary 80% to 90% cure rate currently reported in children. When translated to the adult setting, modern pediatric-type regimens improve the survival to approximately 60% in young adults. The addition of tyrosine kinase inhibitors for patients with Philadelphia chromosome-positive disease and the measurement of minimal residual disease to guide risk stratification and postremission approaches has led to additional improvements in outcomes. Relapsed disease and treatment toxicity-sparing no patient but representing a major concern especially in the elderly-are the most critical current issues awaiting further therapeutic advancement. Recently, there has been considerable progress in understanding the disease biology, specifically the Philadelphia-like signature, as well as other high-risk subgroups. In addition, there are several new agents that will undoubtedly contribute to additional improvement in the current outcomes. The most promising agents are monoclonal antibodies, immunomodulators, and chimeric antigen receptor T cells, and, to a lesser extent, several new drugs targeting key molecular pathways involved in leukemic cell growth and proliferation. This review examines the evidence supporting the increasing role of the new therapeutic tools and treatment options in different disease subgroups, including frontline and relapsed or refractory disease. It is now possible to define the best individual approach on the basis of the emerging concepts of precision medicine.

[Clinical significance of minimal residual disease in patients with Ph-negative precursor B-acute lymphoblastic leukemia]

Objective: To explore the predictive value of minimal residual disease (MRD) level in Ph-negative precursor B-acute lymphoblastic leukemia (ALL) patients. Methods: De novo 193 Ph-negative B-ALL patients from Sep 2010 to Nov 2017 were involved in the study. The patients' MRD evaluation which can be performed by multiparametric flow cytometry (MFC) after 1 month, 3-month, 6-month treatment. Relapse free survival (RFS) and overall survival (OS) were compared in patients with different MRD level. Results: The median follow-up was 22 months. All patients was evaluated at 497 MRD level. Patients who reach the good MRD level at 1 month (<0.1% or ≥0.1%), 3-month (negative or positive), 6-month (negative or positive) had a significantly higher probability of estimated RFS (74.5% vs 29.9%; 75.6% vs 29.7%; 74.6% vs 11.6%) and of estimated OS (67.5% vs 30.3%; 71.6% vs 27.8%; 74.0% vs 15.7%). Patients who reach the MRD negative at all 3 times had a significantly higher probability of estimated RFS (80.5% vs 30.5%) and better estimated OS (77.1% vs 29.4%) compared to patients with at least MRD failure in one time (P<0.001). Multivariable analysis showed MRD level at 3-month was an independent prognostic factor for DFS and OS. Conclusion: MRD is an important prognosis factor for Ph-negative B- ALL patients.

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.

Minimal Residual Disease Assessment and Risk-based Therapy in Acute Lymphoblastic Leukemia

The study of minimal residual disease (MRD) in adult patients with acute lymphoblastic leukemia (ALL) allows a greater refinement of the individual risk classification and is the best support for risk-specific therapy with or without allogeneic hematopoietic cell transplantation (HCT). Using case-specific sensitive molecular probes or multiparametric flow cytometry on marrow samples obtained from the end of induction until midconsolidation, MRD assays can detect up to 1 leukemic cell of 10,000 total mononuclear cells (sensitivity, 0.01%; ie, ≥10⁴). This cutoff, presently bound to technical limitations and subject to improvement, reflects the individual chemosensitivity and is strongly correlated with treatment outcome. The chance for cure is approximately 70% in the MRD-negative subset but only 20% to 30% in MRD-positive patients, in any diagnostic and risk subset. As shown by prospective trials from Germany, Italy, Spain, and France-Switzerland-Belgium, approximately 50% to 70% of unselected adult patients with Philadelphia-negative ALL achieve and maintain an early MRD response, whereas the remainder do not, including a substantial proportion of clinically standard-risk patients, and require an HCT to avert at least partially the risk of relapse. Along with the diffusion of more effective "pediatric-inspired" chemotherapy programs, the MRD analysis is an integral part of a modern management strategy, guiding the decision process to transplant or not, in which case nonrelapse mortality using HCT in first remission-still 10% to 20%-is totally abolished. The use of new agents such as monoclonal antibodies, small inhibitors, and chimeric antigen receptor T cells is opening a new era of MRD-directed therapies, that will further increase survival rates.

Efficacy of Ponatinib Versus Earlier Generation Tyrosine Kinase Inhibitors for Front-line Treatment of Newly Diagnosed Philadelphia-positive Acute Lymphoblastic Leukemia

INTRODUCTION

Complete molecular response (CMR) and 2- and 3-year overall survival (OS) were compared for patients with newly diagnosed Philadelphia-positive acute lymphoblastic leukemia (Ph⁺ ALL) who had undergone front-line combination chemotherapy plus ponatinib versus combination therapy plus earlier generation tyrosine kinase inhibitors (TKIs; imatinib, dasatinib, and nilotinib).

PATIENTS AND METHODS

We identified 26 Ph⁺ ALL studies: 25 of earlier generation TKIs and 1 of ponatinib. The outcomes from studies of combination chemotherapy plus earlier generation TKIs were summarized using pooled estimates with 95% confidence intervals (CIs) from a random-effects meta-analysis. A binomial distribution was assumed to calculate the 95% CIs for the results from the single-arm combination chemotherapy plus ponatinib trial. Adjusted logistic meta-regression analyses were used to compare the outcomes between the TKI groups.

RESULTS

The percentage of patients achieving a CMR was greater with combination chemotherapy plus ponatinib (79%) than the pooled percentage of patients achieving a CMR with combination chemotherapy plus earlier generation TKIs (34%). Greater OS was observed with ponatinib compared with the pooled OS for earlier generation TKIs (2-year, 83% vs. 58%; 3-year, 79% vs. 50%). Odds ratios for ponatinib versus earlier generation TKIs were 6.09 (95% CI, 1.16-31.90; P = .034) for CMR, 3.70 (95% CI, 0.93-14.73; P = .062) for 2-year OS, and 4.49 (95% CI, 1.00-20.13; P = .050) for 3-year OS.

CONCLUSION

Ponatinib plus chemotherapy might be associated with better outcomes than chemotherapy with earlier generation TKIs in patients with newly diagnosed Ph⁺ ALL.

Hematopoietic Stem Cell Transplantation for Adult Philadelphia-Negative Acute Lymphoblastic Leukemia in the First Complete Remission in the Era of Minimal Residual Disease

PURPOSE OF REVIEW

The purpose of this review is to discuss the potential role of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for Philadelphia-negative (Ph^-) adult acute lymphoblastic leukemia (ALL) in first complete remission (CR1) in the era of minimal residual disease (MRD).

RECENT FINDINGS

Allo-HSCT continues to have a role in the therapy of a selected group of high-risk adult patients with ALL in CR1. Although the clinical significance of MRD has been studied less extensively in adults with ALL than in children, recent studies support its role as the strongest prognostic factor that can identify patients that are unlikely to be cured by standard chemotherapy and benefit from undergoing allo-HSCT. In addition, MRD status both pre- and post-HSCT has been found to correlate directly with the risk of relapse. Currently, the clinical challenge consists on applying MRD and molecular failure to integrate novel agents and immunotherapy to lower MRD before allo-HSCT and to modulate the graft versus leukemia (GVL) effect after transplant.

Minimal residual disease in adult ALL: technical aspects and implications for correct clinical interpretation

Nowadays, minimal residual disease (MRD) is accepted as the strongest independent prognostic factor in acute lymphoblastic leukemia (ALL). It can be detected by molecular methods that use leukemia-specific or patient-specific molecular markers (fusion gene transcripts, or immunoglobulin/T-cell receptor [IG/TR] gene rearrangements), and by multi-parametric flow cytometry. The sensitivity and specificity of these methods can vary across treatment time points and therapeutic settings. Thus, knowledge of the principles and limitations of each technology is of the utmost importance for correct interpretation of MRD results. Time will tell whether new molecular and flow cytometric high-throughput technologies can overcome the limitations of current standard methods and eventually bring additional benefits. MRD during standard ALL chemotherapy is the strongest overall prognostic indicator and has therefore been used for refining initial treatment stratification. Moreover, MRD positivity after the maintenance phase of treatment may point to an impending relapse and thus enable salvage treatment to be initiated earlier, which could possibly improve treatment results. The prognostic relevance of pretransplantation MRD was shown by several studies, and MRD high-risk patients were shown to benefit from stem cell transplantation (SCT). Also, MRD positivity after SCT correlates with worse outcomes. In addition, MRD information is very instructive in current clinical trials that test novel agents to evaluate their treatment efficacy. Although conventional clinical risk factors lose their independent prognostic significance when combined with MRD information, recently identified genetic markers may further improve the treatment stratification in ALL.

Minimal residual disease in adult ALL: technical aspects and implications for correct clinical interpretation

Nowadays, minimal residual disease (MRD) is accepted as the strongest independent prognostic factor in acute lymphoblastic leukemia (ALL). It can be detected by molecular methods that use leukemia-specific or patient-specific molecular markers (fusion gene transcripts, or immunoglobulin/T-cell receptor [IG/TR] gene rearrangements), and by multi-parametric flow cytometry. The sensitivity and specificity of these methods can vary across treatment time points and therapeutic settings. Thus, knowledge of the principles and limitations of each technology is of the utmost importance for correct interpretation of MRD results. Time will tell whether new molecular and flow cytometric high-throughput technologies can overcome the limitations of current standard methods and eventually bring additional benefits. MRD during standard ALL chemotherapy is the strongest overall prognostic indicator and has therefore been used for refining initial treatment stratification. Moreover, MRD positivity after the maintenance phase of treatment may point to an impending relapse and thus enable salvage treatment to be initiated earlier, which could possibly improve treatment results. The prognostic relevance of pretransplantation MRD was shown by several studies, and MRD high-risk patients were shown to benefit from stem cell transplantation (SCT). Also, MRD positivity after SCT correlates with worse outcomes. In addition, MRD information is very instructive in current clinical trials that test novel agents to evaluate their treatment efficacy. Although conventional clinical risk factors lose their independent prognostic significance when combined with MRD information, recently identified genetic markers may further improve the treatment stratification in ALL.

TP53 in adult acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is characterized by a great biological and clinical heterogeneity. Despite most adult patients enter complete hematologic remission after induction therapy only 40% survive five or more years. Over the last 20 years, the definition of an accurate biologic leukemia profile and the minimal residual disease evaluation in addition to conventional risk criteria led to a significant improvement for the risk stratification. The alterations of the oncosuppressor gene TP53, including deletions, sequence mutations and defect in its expression due to regulatory defects, define a new important predictor of adverse outcome. More recently, new drugs have been developed with the aim of targeting p53 protein itself or its regulatory molecules, such as Mdm2, and restoring the pathway functionality. Therefore, TP53 alterations should be considered in the diagnostic work-up to identify high risk ALL patients in need of intensive treatment strategies or eligible for new innovative targeted therapies.

Continuing challenges and current issues in acute lymphoblastic leukemia

Conventional cytotoxic chemotherapy used to treat acute lymphoblastic leukemia (ALL) has resulted into high cure rates for pediatric patients, however outcomes for adult patients remain suboptimal. The 5-year overall survival is only 30-40% in adults and elderly patients with ALL compared to 90% in children. We have seen major advances in our understanding and management of ALL related to identification of new cytogenetic and molecular abnormalities and development of novel targeted agents for the treatment of ALL. The addition of tyrosine kinase inhibitors, monoclonal antibodies and novel immune therapies (e.g. bispecific T cell engager [BiTE] and chimeric antigen receptor [CAR] T cells) has resulted in improved outcomes. These new developments are changing the treatment paradigm of adults ALL from a 'one size fits all' approach to a more individualized treatment approach based on immunophenotypic, cytogenetic and molecular features. In this article we review recent diagnostic and therapeutic advances along with the challenges in the treatment of patients with ALL.

Complete Hematologic and Molecular Response in Adult Patients With Relapsed/Refractory Philadelphia Chromosome-Positive B-Precursor Acute Lymphoblastic Leukemia Following Treatment With Blinatumomab: Results From a Phase II, Single-Arm, Multicenter Study

Purpose Few therapeutic options are available for patients with Philadelphia chromosome-positive (Ph⁺) B-precursor acute lymphoblastic leukemia (ALL) who progress after failure of tyrosine kinase inhibitor (TKI) -based therapy. Here, we evaluated the efficacy and tolerability of blinatumomab in patients with relapsed or refractory Ph⁺ ALL. Patients and Methods This open-label phase II study enrolled adults with Ph⁺ ALL who had relapsed after or were refractory to at least one second-generation or later TKI or were intolerant to second-generation or later TKIs and intolerant or refractory to imatinib. Blinatumomab was administered in 28-day cycles by continuous intravenous infusion. The primary end point was complete remission (CR) or CR with partial hematologic recovery (CRh) during the first two cycles. Major secondary end points included minimal residual disease response, rate of allogeneic hematopoietic stem-cell transplantation, relapse-free survival, overall survival, and adverse events (AEs). Results Of 45 patients, 16 (36%; 95% CI, 22% to 51%) achieved CR/CRh during the first two cycles, including four of 10 patients with the T315I mutation; 88% of CR/CRh responders achieved a complete minimal residual disease response. Seven responders (44%) proceeded to allogeneic hematopoietic stem-cell transplantation, including 55% (six of 11) of transplantation-naïve responders. Median relapse-free survival and overall survival were 6.7 and 7.1 months, respectively. The most frequent AEs were pyrexia (58%), febrile neutropenia (40%), and headache (31%). Three patients had cytokine release syndrome (all grade 1 or 2), and three patients had grade 3 neurologic events, one of which (aphasia) required temporary treatment interruption. There were no grade 4 or 5 neurologic events. Conclusion Single-agent blinatumomab showed antileukemia activity in high-risk patients with Ph⁺ ALL who had relapsed or were refractory to TKIs. AEs were consistent with previous experience in Ph^- ALL.

Minimal Residual Disease at First Achievement of Complete Remission Predicts Outcome in Adult Patients with Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia

We evaluated the prognostic effect of minimal residual disease at first achievement of complete remission (MRD at CR1) in adult patients with Philadelphia chromosome-negative acute lymphoblastic leukemia (ALL). A total of 97 patients received treatment in our center between 2007 and 2012 were retrospectively reviewed in this study. Patients were divided into two arms according to the post-remission therapy (chemotherapy alone or allogeneic hematopoietic stem cell transplantation (allo-HSCT)) they received. MRD was detected by four-color flow cytometry. We chose 0.02% and 0.2% as the cut-off points of MRD at CR1 for risk stratification using receiver operating characteristic analysis. The 3-year overall survival (OS) and leukemia free survival (LFS) rates for the whole cohort were 46.2% and 40.5%. MRD at CR1 had a significantly negative correlation with survival in both arms. Three-year OS rates in the chemotherapy arm were 70.0%, 25.2%, 0% (P = 0.003) for low, intermediate, and high levels of MRD at CR1, respectively. Three-year OS rates in the transplant arm were 81.8%, 64.3%, 27.3% (P = 0.005) for low, intermediate, and high levels of MRD at CR1, respectively. Multivariate analysis confirmed that higher level of MRD at CR1 was a significant adverse factor for OS and LFS. Compared with chemotherapy alone, allo-HSCT significantly improved LFS rates in patients with intermediate (P = 0.005) and high (P = 0.022) levels of MRD at CR1, but not patients with low level of MRD at CR1 (P = 0.851). These results suggested that MRD at CR1 could strongly predict the outcome of adult ALL. Patients with intermediate and high levels of MRD at CR1 would benefit from allo-HSCT.

Minimal Residual Disease Monitoring in Adult ALL to Determine Therapy

Almost 90 % of children and 50 % of adults with acute lymphoblastic leukemia (ALL) are cured by modern treatment regimens, with significant variations due to several disease- and host-related characteristics. The attainment of an early remission and the avoidance of relapse and treatment-related mortality are the fundamental therapeutic steps. In remission patients, the assessment of the disease response to early intensive therapy through the detection and monitoring of minimal residual disease (MRD) can accurately refine the individual prognosis and is increasingly used to support a risk-oriented treatment strategy. In this way, only the patients with an unfavorable MRD response are preferably selected for allogeneic stem cell transplantation, irrespective of their clinical risk class. This choice spares transplant-related toxicities to MRD responsive cases. Further advancement is expected by integrating the MRD analysis with improved pediatric-type regimens and novel targeting agents for ALL subsets at higher risk of relapse.

Clinical updates in adult acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a clonal disease characterized by B or T lineage. Here we cover the clinical manifestations, pathophysiology and therapy for ALL. Additionally, we will discuss the evidence for minimal residual disease assessment, novel molecular targets and newly developed targeted therapies. The separation of ALL into Philadelphia chromosome positive and recently into Philadelphia-like disease represents the most exciting developments in this disease. Finally, the advent of new immunotherapeutic approaches led us to predict that in few years, ALL therapy might be based heavily on non-chemotherapeutic approaches.

Good Outcome for Very High Risk Adult B-cell Acute Lymphoblastic Leukaemia Carrying Genetic Abnormalities t(4;11)(q21;q23) or t(9;22)(q34;q11), if Promptly Submitted to Allogeneic Transplantation, after Obtaining a Good Molecular Remission

Background and Objectives

Acute lymphoblastic leukaemia (ALL) carrying t(9;22) or t(4;11) genetic abnormalities represents a very high risk subtype of disease (VHR-ALL). Hematopoietic stem cell transplantation (HSCT) remains the best curative option not only for t(4;11) ALL, but also for t(9;22) ALL in the tyrosin-kinase inhibitors era. In the last years, low molecular level of minimal residual disease (MRD) before HSCT was reported as one of the best favourable indexes for survival in ALL. Here we observed that even these patients can show a favourable outcome if submitted to HSCT with very low MRD.

Methods

We considered 18 consecutive VHR-ALL patients eligible to HSCT. 16 of them were transplanted in first remission, as soon as possible, employing myelo-ablative conditioning regimens. Molecular MRD has been evaluated before and after HSCT.

Results

Immediately before HSCT, MRD revealed: complete molecular remission (MRD^neg) for five patients, and a level <1×10⁻³ for seven patients. 100 days after HSCT we had: MRD^neg for seven patients and a decrease for all the others after HSCT. After the tapering of immunosuppressive drugs, 13 patients reached the MRD^neg in a median time of 8 months (range 3–16). In the intention to treat analysis, 14/18 patients are alive and disease free at the date of analysis. Overall survival and event free survival is of 78% and 66% respectively, with an average follow-up of 45 months (range 6–84) since HSCT.

Conclusion

Early transplantation with low MRD level seems to be correlated with a favourable outcome also in VHR-ALL.

How I treat acute lymphoblastic leukemia in older adolescents and young adults

At the intersection between children and older adults, the care of adolescent and young adult (AYA) patients with acute lymphoblastic leukemia (ALL) poses unique challenges and issues beyond those faced by other age groups. Although the survival of AYA patients is inferior to younger children, growing evidence suggests that AYA patients have improved outcomes, with disease-free survival rates of 60% to 70%, when treated with pediatric-based approaches. A holistic approach, incorporating a multidisciplinary team, is a key component of successful treatment of these AYA patients. With the appropriate support and management of toxicities during and following treatment, these regimens are well tolerated in the AYA population. Even with the significant progress that has been made during the last decade, patients with persistence of minimal residual disease (MRD) during intensive therapy still have a poor prognosis. With new insights into disease pathogenesis in AYA ALL and the availability of disease-specific kinase inhibitors and novel targeted antibodies, future studies will focus on individualized therapy to eradicate MRD and result in further improvements in survival. This case-based review will discuss the biology, pharmacology, and psychosocial aspects of AYA patients with ALL, highlighting our current approach to the management of these unique patients.

Minimal residual disease diagnostics in acute lymphoblastic leukemia: need for sensitive, fast, and standardized technologies

Monitoring of minimal residual disease (MRD) has become routine clinical practice in frontline treatment of virtually all childhood acute lymphoblastic leukemia (ALL) and in many adult ALL patients. MRD diagnostics has proven to be the strongest prognostic factor, allowing for risk group assignment into different treatment arms, ranging from significant treatment reduction to mild or strong intensification. Also in relapsed ALL patients and patients undergoing stem cell transplantation, MRD diagnostics is guiding treatment decisions. This is also why the efficacy of innovative drugs, such as antibodies and small molecules, are currently being evaluated with MRD diagnostics within clinical trials. In fact, MRD measurements might well be used as a surrogate end point, thereby significantly shortening the follow-up. The MRD techniques need to be sensitive (≤10(-4)), broadly applicable, accurate, reliable, fast, and affordable. Thus far, flow cytometry and polymerase chain reaction (PCR) analysis of rearranged immunoglobulin and T-cell receptor genes (allele-specific oligonucleotide [ASO]-PCR) are claimed to meet these criteria, but classical flow cytometry does not reach a solid 10(-4), whereas classical ASO-PCR is time-consuming and labor intensive. Therefore, 2 high-throughput technologies are being explored, ie, high-throughput sequencing and next-generation (multidimensional) flow cytometry, both evaluating millions of sequences or cells, respectively. Each of them has specific advantages and disadvantages.

Incidence, clinical and biological characteristics and outcome of secondary acute lymphoblastic leukemia after solid organ or hematologic malignancy

Acute lymphoblastic leukemia (ALL) following solid organ or hematologic malignancy (secondary ALL, s-ALL) is not well characterized. We analyzed the characteristics and outcome of patients with s-ALL and compared them with those of patients with de novo- ALL. Of 448 patients, 24 (5%) had previous neoplasia. Sixteen patients had received previous cytotoxic therapy (therapy-associated ALL, t-ALL), and eight had not (antecedent-malignancy ALL, am-ALL). Except for more advanced age in patients with s-ALL, no statistically significant differences were observed in WBC count, CNS involvement, immunophenotype or cytogenetics between the groups, nor in complete remission (t-ALL: 94%; am-ALL: 75%; de novo-ALL: 85%), 3-year remission duration (58%; 50%; 72%), overall survival (71%; 38%; 60%) or event-free survival (53%, 38%; 53%). Our study did not show poor clinical or cytogenetic features or inferior outcome in ALL patients with antecedent neoplastic disease, irrespective of the type of treatment received for the neoplasia.

Prognostic impact of minimal residual disease in adult acute lymphoblastic leukemia

SUMMARY 

While adult acute lymphoblastic leukemia (ALL) is curable in 40–50% of the patients, the individual prognosis is rather unpredictable due to associated biological and clinical risk factors. In both B- and T-precursor ALL, minimal residual disease (MRD) represents the most sensitive prognostic marker, useful to support critical treatment decisions, ranging from allogeneic stem cell transplantation in patients with inadequate MRD response to chemotherapy only in MRD responsive ones. This optimized risk-adapted strategy allows to spare transplant-associated morbidity and mortality in patients curable by chemotherapy. Further progress is expected from the integration of the MRD-based strategy with improved pediatric-type regimens and novel targeting agents for discrete ALL subsets. These changes are increasing the cure rate to above 50%.