SWOG S0910: a phase 2 trial of clofarabine/cytarabine/epratuzumab for relapsed/refractory acute lymphocytic leukaemia

Antibody-Based and Other Novel Agents in Adult B-Cell Acute Lymphoblastic Leukemia

Despite notable progress in managing B-cell acute lymphoblastic leukemia (B-ALL) over recent decades, particularly in pediatric cohorts where the 5-year overall survival (OS) reaches 90%, outcomes for the 10-15% with relapsed and refractory disease remain unfavorable. This disparity is further accentuated in adults, where individuals over the age of 40 years undergoing aggressive multiagent chemotherapy continue to have lower survival rates. While the adoption of pediatric-inspired treatment protocols has enhanced complete remission (CR) rates among younger adults, 20-30% of these patients experience relapse, resulting in a subsequent 5-year OS rate of 40-50%. For relapsed B-ALL in adults, there is no universally accepted standard salvage therapy, and the median OS is short. The cornerstone of B-ALL treatment continues to be the utilization of combined cytotoxic chemotherapy regimens to maximize early and durable disease control. In this manuscript, we go beyond the multiagent chemotherapy medications developed prior to the 1980s and focus on the incorporation of antibody-based therapy for B-ALL with an eye on existing and upcoming approved indications for blinatumomab, inotuzumab ozogamicin, other monoclonal antibodies, and chimeric antigen receptor (CAR) T cell products in frontline and relapsed/refractory settings. In addition, we discuss emerging investigational therapies that harness the therapeutic vulnerabilities of the disease through targeting apoptosis, modifying epigenetics, and inhibiting the mTOR pathway.

The RORɣ/SREBP2 pathway is a master regulator of cholesterol metabolism and serves as potential therapeutic target in t(4;11) leukemia

Dysregulated cholesterol homeostasis promotes tumorigenesis and progression. Therefore, metabolic reprogramming constitutes a new hallmark of cancer. However, until today, only few therapeutic approaches exist to target this pathway due to the often-observed negative feedback induced by agents like statins leading to controversially increased cholesterol synthesis upon inhibition. Sterol regulatory element-binding proteins (SREBPs) are key transcription factors regulating the synthesis of cholesterol and fatty acids. Since SREBP2 is difficult to target, we performed pharmacological inhibition of retinoic acid receptor (RAR)-related orphan receptor gamma (RORγ), which acts upstream of SREBP2 and serves as master regulator of the cholesterol metabolism. This resulted in an inactivated cholesterol-related gene program with significant downregulation of cholesterol biosynthesis. Strikingly, these effects were more pronounced than the effects of fatostatin, a direct SREBP2 inhibitor. Upon RORγ inhibition, RNA sequencing showed strongly increased cholesterol efflux genes leading to leukemic cell death and cell cycle changes in a dose- and time-dependent manner. Combinatorial treatment of t(4;11) cells with the RORγ inhibitor showed additive effects with cytarabine and even strong anti-leukemia synergism with atorvastatin by circumventing the statin-induced feedback. Our results suggest a novel therapeutic strategy to inhibit tumor-specific cholesterol metabolism for the treatment of t(4;11) leukemia.

A systematic review on the cost-effectiveness assessment of tisagenlecleucel for refractory or relapsing B-cell acute lymphoblastic leukemia (R/R B-ALL) treatment in children and young adults

BACKGROUND AIMS

The advanced therapy product tisagenlecleucel is a CD19-directed genetically modified autologous T-cell immunotherapy that has brought hope for children and young adults with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We sought to evaluate the cost-effectiveness of tisagenlecleucel compared with conventional salvage therapies in pediatric and young adult patients with R/R B-ALL.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses parameters as registered in International Prospective Register of Systematic Reviews (CRD42021266998). Literature was searched using the MEDLINE databases via PubMed, EMBASE, Lilacs, the Cochrane Central Register of Controlled Trials and Web of Science in January 2022. Titles were screened independently by two reviewers. Articles deemed to meet the inclusion criteria were screened independently on abstract, and full texts were reviewed.

RESULTS

In total, 5627 publications were identified, from which six eligible studies were selected. The conventional therapies identified were blinatumomab (Blina), clofarabine monotherapy (Clo-M), clofarabine combined with cyclophosphamide and etoposide (Clo-C) and the combination of fludarabine, cytarabine and idarubicin (FLA-IDA). The discounted incremental cost-effectiveness ratio (ICER) per quality-adjusted life year (QALY) gained for tisagenlecleucel compared with Clo-C and Blina averages was $38 837 and $25 569, respectively. In relation to the cost of the drug, the average of tisagenlecleucel was approximately 4.3 times, 10.8 times or 4.7 times greater than the Clo-M, Clo-C and Blina, respectively.

CONCLUSIONS

This systematic review highlighted that tisagenlecleucel is a much more expensive therapy than conventional alternatives. However, tisagenlecleucel performed well on the ICER, not exceeding $100 000/QALY. It was also found that the advanced therapy product was more effective than the conventional small molecule and biological drugs, in terms of life years and QALY gained.

Flow cytometric assessment for minimal/measurable residual disease in B lymphoblastic leukemia/lymphoma in the era of immunotherapy

Minimal/measurable residual disease (MRD) is the most important independent prognostic factor for patients with B-lymphoblastic leukemia (B-LL). MRD post therapy has been incorporated into risk stratification and clinical management, resulting in substantially improved outcomes in pediatric and adult patients. Currently, MRD in B-ALL is most commonly assessed by multiparametric flow cytometry and molecular (polymerase chain reaction or high-throughput sequencing based) methods. The detection of MRD by flow cytometry in B-ALL often begins with B cell antigen-based gating strategies. Over the past several years, targeted immunotherapy directed against B cell markers has been introduced in patients with relapsed or refractory B-ALL and has demonstrated encouraging results. However, targeted therapies have significant impact on the immunophenotype of leukemic blasts, in particular, downregulation or loss of targeted antigens on blasts and normal B cell precursors, posing challenges for MRD detection using standard gating strategies. Novel flow cytometric approaches, using alternative strategies for population identification, sometimes including alternative gating reagents, have been developed and implemented to monitor MRD in the setting of post targeted therapy.

Changing Landscape in the Treatment of Adult Acute Lymphoblastic Leukemia (ALL)

Acute lymphoblastic leukemia (ALL) is a rare hematological malignancy characterized by proliferation and accumulation of premature lymphoid blasts. Depending on risk factors, the survival of acute lymphoblastic leukemia has significantly improved over the last decades. During the last years, measurable residual disease (MRD) assessment has evolved into one of the most sensitive markers for prognosis and risk of relapse. For this reason, measurable residual disease detection and monitoring count as standard evaluation in patients with acute lymphoblastic leukemia. Allogeneic stem cell transplantation is still the recommended treatment option for patients with high and highest risk profiles as well as for relapsed or refractory settings. The increased understanding of the pathomechanism and heterogeneity of acute lymphoblastic leukemia has led to the development of several novel therapeutic opportunities such as tyrosine-kinase inhibitors, antibody-based therapies and CAR-T cells with the aim of improving clinical outcomes. Furthermore, the major advances in disease understanding of ALL have led to the identification of different subgroups and better disease stratification. Even though novel therapy targets are constantly developed, acute lymphoblastic leukemia remains a challenging and life-threatening disease. To improve the historically unsatisfying result in therapy of adult acute lymphoblastic leukemia many clinical trials have recently been initiated to determine the optimum combination regimens of novel and old agents for adult acute lymphoblastic leukemia.

Monoclonal antibodies for the treatment of acute lymphocytic leukemia: A literature review

BACKGROUND

Acute lymphocytic leukemia (ALL) is a type of blood cancer that is more prevalent in children. Several treatment methods are available for ALL, including chemotherapy, upfront treatment regimens, and pediatric-inspired regimens for adults. Monoclonal antibodies (Mabs) are the novel Food and Drug Administration (FDA) approved remedies for the relapsed/refractory (R/R) adult ALL. In this article, we aimed to review studies that investigated the efficacy and safety of Mabs on ALL.

METHODS

We gathered studies through a complete search with all proper related keywords in ISI Web of Science, SID, Scopus, Google Scholar, Science Direct, and PubMed for English language publications up to 2020.

RESULTS

The most commonly studied Mabs for ALL therapies are CD-19, CD-20, CD-22, and CD-52. The best results have been reported in the administration of blinatumomab, rituximab, ofatumumab, and inotuzumab with acceptable low side effects.

CONCLUSION

Appling personalized approach for achieving higher efficacy is one of the most important aspects of treatment. Moreover, we recommend that the wide use of these Mabs depends on designing further cost-effectiveness trials in this field.

Emerging Monoclonal Antibody Therapy for the Treatment of Acute Lymphoblastic Leukemia

The treatment of adults with ALL has undergone tremendous progress over the past 15 years. The advances have been particularly marked with B-lineage ALL. The development of bispecific antibodies directed against CD19 ushered in a new era in overcoming persistent minimal disease in newly diagnosed ALL patients as well as successfully treating those with relapsed disease. The immune-conjugates targeting CD22 have also had a similarly impressive role in improving the outcome in such patients. These advances are now being extended to frontline regimens for B-lineage ALL, including the Philadelphia-chromosome-positive subtype. Over the past decade, the development of chimeric antigen receptor T-cell therapy (CAR-T) has ushered in a new era, opening up hope when none was available for patients with particularly advanced disease. Such advances come at a considerable price for toxicity, which, however, are lessening with experience and the development of new agents to ameliorate some of the toxicities. Unfortunately, the progress for T-cell in ALL has lagged behind that of B-lineage ALL. Of late, however, there are preliminary results of potentially exciting data using monoclonal antibodies against CD38, in the form of daratumumab, and it is hoped that these will lead to an equally successful advance in the treatment of T-ALL. Despite all these advances, ALL in adults remains a formidable disease. While ongoing progress is being made, also in the therapy of older patients, we are still lagging behind the almost totally curative potential of current therapy for childhood ALL.

Targeted Therapy in Acute Lymphoblastic Leukaemia

The last decade has seen a significant leap in our understanding of the wide range of genetic lesions underpinning acute lymphoblastic leukaemia (ALL). Next generation sequencing has led to the identification of driver mutations with significant implications on prognosis and has defined entities such as BCR-ABL-like ALL, where targeted therapies such as tyrosine kinase inhibitors (TKIs) and JAK inhibitors may play a role in its treatment. In Philadelphia positive ALL, the introduction of TKIs into frontline treatment regimens has already transformed patient outcomes. In B-ALL, agents targeting surface receptors CD19, CD20 and CD22, including monoclonal antibodies, bispecific T cell engagers, antibody drug conjugates and chimeric antigen receptor (CAR) T cells, have shown significant activity but come with unique toxicities and have implications for how treatment is sequenced. Advances in T-ALL have lagged behind those seen in B-ALL. However, agents such as nelarabine, bortezomib and CAR T cell therapy targeting T cell antigens have been examined with promising results seen. As our understanding of disease biology in ALL grows, as does our ability to target pathways such as apoptosis, through BH3 mimetics, chemokines and epigenetic regulators. This review aims to highlight a range of available and emerging targeted therapeutics in ALL, to explore their mechanisms of action and to discuss the current evidence for their use.

Targeting CD22 for the Treatment of B-Cell Malignancies

Immunotherapeutic agents play an increasingly important role in the treatment of B-cell malignancies. CD19 and CD20 are common targets for lymphoid malignancies, though patients who relapse have few therapeutic options remaining. CD22 is a cell surface sialoglycoprotein uniquely present on B-cells and regulates B-cell function and proliferation. Thus, it is an appealing therapeutic target for autoimmune disorders and B-cell malignancies. A variety of therapies targeting CD22 have been developed, including monoclonal antibodies, antibody-drug conjugates, radioimmunoconjugates, chimeric antigen receptor T cells, and bispecific antibodies. Here, we review the biology of CD22 and key therapies targeting CD22 in lymphoid malignancies.

Mechanisms of Immune Evasion in Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) results from a clonal expansion of abnormal lymphoid progenitors of B cell (BCP-ALL) or T cell (T-ALL) origin that invade bone marrow, peripheral blood, and extramedullary sites. Leukemic cells, apart from their oncogene-driven ability to proliferate and avoid differentiation, also change the phenotype and function of innate and adaptive immune cells, leading to escape from the immune surveillance. In this review, we provide an overview of the genetic heterogeneity and treatment of BCP- and T-ALL. We outline the interactions of leukemic cells in the bone marrow microenvironment, mainly with mesenchymal stem cells and immune cells. We describe the mechanisms by which ALL cells escape from immune recognition and elimination by the immune system. We focus on the alterations in ALL cells, such as overexpression of ligands for various inhibitory receptors, including anti-phagocytic receptors on macrophages, NK cell inhibitory receptors, as well as T cell immune checkpoints. In addition, we describe how developing leukemia shapes the bone marrow microenvironment and alters the function of immune cells. Finally, we emphasize that an immunosuppressive microenvironment can reduce the efficacy of chemo- and immunotherapy and provide examples of preclinical studies showing strategies for improving ALL treatment by targeting these immunosuppressive interactions.

Invasive Fungal Diseases in Children with Hematological Malignancies Treated with Therapies That Target Cell Surface Antigens: Monoclonal Antibodies, Immune Checkpoint Inhibitors and CAR T-Cell Therapies

Since 1985 when the first agent targeting antigens on the surface of lymphocytes was approved (muromonab-CD3), a multitude of such therapies have been used in children with hematologic malignancies. A detailed literature review until January 2021 was conducted regarding pediatric patient populations treated with agents that target CD2 (alefacept), CD3 (bispecific T-cell engager [BiTE] blinatumomab), CD19 (denintuzumab mafodotin, B43, BiTEs blinatumomab and DT2219ARL, the immunotoxin combotox, and chimeric antigen receptor [CAR] T-cell therapies tisagenlecleucel and axicabtagene ciloleucel), CD20 (rituximab and biosimilars, 90Y-ibritumomab tiuxetan, ofatumumab, and obinutuzumab), CD22 (epratuzumab, inotuzumab ozogamicin, moxetumomab pasudotox, BiTE DT2219ARL, and the immunotoxin combotox), CD25 (basiliximab and inolimomab), CD30 (brentuximab vedotin and iratumumab), CD33 (gemtuzumab ozogamicin), CD38 (daratumumab and isatuximab), CD52 (alemtuzumab), CD66b (90Y-labelled BW 250/183), CD248 (ontuxizumab) and immune checkpoint inhibitors against CTLA-4 (CD152; abatacept, ipilimumab and tremelimumab) or with PD-1/PD-L1 blockade (CD279/CD274; atezolizumab, avelumab, camrelizumab, durvalumab, nivolumab and pembrolizumab). The aim of this narrative review is to describe treatment-related invasive fungal diseases (IFDs) of each category of agents. IFDs are very common in patients under blinatumomab, inotuzumab ozogamicin, basiliximab, gemtuzumab ozogamicin, alemtuzumab, and tisagenlecleucel and uncommon in patients treated with moxetumomab pasudotox, brentuximab vedotin, abatacept, ipilimumab, pembrolizumab and avelumab. Although this new era of precision medicine shows promising outcomes of targeted therapies in children with leukemia or lymphoma, the results of this review stress the necessity for ongoing surveillance and suggest the need for antifungal prophylaxis in cases where IFDs are very common complications.

Antibody based therapy in relapsed acute lymphoblastic leukemia

Outcomes for relapsed and refractory acute lymphoblastic leukemia (ALL) remain poor. With the advent of targeted monoclonal antibodies and antibody constructs, these outcomes have been significantly improved both in the frontline and salvage setting. These targets include a bispecific antibody that targets both CD3 and CD19, known as blinatumomab, as well as a conjugated antibody that targets CD22, known as inotuzumab ozogamicin. These agents have been thoroughly studied and successively approved for use as monotherapy, however, more recently they have been incorporated in combination or sequentially with cytotoxic chemotherapy. In this chapter, we will discuss the role that these monoclonal antibodies play as monotherapy and in combination in the treatment of ALL in the salvage setting, and how they continue to transform the treatment management of relapsed and refractory ALL.

Optimal approach to the treatment of young adults with acute lymphoblastic leukemia in 2020

Akin to the introduction of tyrosine kinase inhibitors to Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL), pediatric-based asparaginase-heavy approaches have revolutionized the treatment of young adults with the Philadelphia chromosome-negative subset the past decades. Once again, we are approaching a new era. An era of precision medicine with immunotherapy and other molecularly targeted treatments that offers unique opportunities to customize treatment intensity with or without hematopoietic stem cell transplantation, reduce the burden of toxicities, and combat persistent residual disease. Recently approved agents for refractory/relapsed B-cell precursor ALL include the chimeric antigen receptor-modified T-cells, the anti-CD22 monoclonal antibody-drug conjugate, inotuzumab ozogamicin, and the bispecific anti-CD19 T-cell engager, blinatumomab. These agents are expected to move widely into the frontline setting along with the proteasome inhibitors, bortezomib and carfilzomib, as well as tyrosine kinase inhibitors for Philadelphia-like rearrangements that are especially frequent among young adults. To this add the BH3 mimetics, venetoclax and navitoclax, which are being widely explored in refractory/relapsed as well as frontline settings for B- and T-cell ALL. The promising anti-CD38 monoclonal antibody, daratumumab, is entering the scene of refractory/relapsed T-ALL, whereas the old purine analogue, nelarabine, is being evaluated in a new upfront setting. This review focuses on 2 main questions: How do we optimize frontline as well as salvage ALL treatment of young adults in the 2020s? Not least, how do we address the current burden of serious toxicities unique to young adults?

Bispecific T-cell engaging antibodies in B-cell precursor acute lymphoblastic leukemias: focus on blinatumomab

Bispecific T-cell engaging antibodies are constructs engineered to bind to two different antigens, one to a tumor-specific target and the other to CD3-positive T cells or natural killer (NK) cells. Blinatumomab engages CD19 and CD3, performing effective serial lysis. The clinical development program in acute lymphoblastic leukemia (ALL) includes clinical trials in relapsed or refractory (R/R) patients and in B-cell precursor (BCP) ALL patients with measurable residual disease. Several trials are currently being conducted in de novo BCP-ALL, either in induction, consolidation, or before or after hematopoietic stem cell transplant. Combination with other targeted therapies or with other immunotherapeutic approaches are also underway. Several strategies are aimed to optimize the use of blinatumomab either by overcoming the mechanisms of resistance (e.g. inhibition of PD-1/PD-L1) or by improvements in the route of application, among others.

Single-Arm Phase II Trials of Combination Therapies: A Review of the CTEP Experience 2008-2017

Designing and interpreting single-arm phase II trials of combinations of agents is challenging because it can be difficult, based on historical data, to identify levels of activity for which the combination would be worth pursuing. We identified Cancer Therapy Evaluation Program single-arm combination trials that were activated in 2008-2017 and tabulated their design characteristics and results. Positive trials were evaluated as to whether they provided credible evidence that the combination was better than its constituents. A total of 125 trials were identified, and 120 trials had results available. Twelve had designs where eligible patients were required to be resistant or refractory to all but one element of the combination. Only 17.8% of the 45 positive trials were deemed to provide credible evidence that the combination was better than its constituents. Of the 10 positive trials with observed rates 10 percentage points higher than their upper (alternative hypothesis) targets, only five were deemed to provide such credible evidence. Many trials were definitively negative, with observed clinical activity at or below their lower (null hypothesis) targets. Ideally, use of single-arm combination trials should be restricted to settings where each agent is known to have minimal monotherapy activity (and a randomized trial is infeasible). In these settings, an observed signal is attributable to synergy and thus could be used to decide whether the combination is worth pursuing. In other settings, credible evidence can still be obtained if the observed activity is much higher than expected, but experience suggests that this is a rare occurrence.

Let's Talk About BiTEs and Other Drugs in the Real-Life Setting for B-Cell Acute Lymphoblastic Leukemia

Background: Therapy for acute lymphoblastic leukemia (ALL) are currently initially efficient, but even if a high percentage of patients have an initial complete remission (CR), most of them relapse. Recent data shows that immunotherapy with either bispecific T-cell engagers (BiTEs) of chimeric antigen receptor (CAR) T cells can eliminate residual chemotherapy-resistant B-ALL cells.

Objective: The objective of the manuscript is to present improvements in the clinical outcome for chemotherapy-resistant ALL in the real-life setting, by describing Romania's experience with bispecific antibodies for B-cell ALL.

Methods: We present the role of novel therapies for relapsed B-cell ALL, including the drugs under investigation in phase I-III clinical trials, as a potential bridge to transplant. Blinatumomab is presented in a critical review, presenting both the advantages of this drug, as well as its limitations.

Results: Bispecific antibodies are discussed, describing the clinical trials that resulted in its approval by the FDA and EMA. The real-life setting for relapsed B-cell ALL is described and we present the patients treated with blinatumomab in Romania.

Conclusion: In the current manuscript, we present blinatumomab as a therapeutic alternative in the bridge-to-transplant setting for refractory or relapsed ALL, to gain a better understanding of the available therapies and evidence-based data for these patients in 2019.

Current Advances in Immunotherapy for Acute Leukemia: An Overview of Antibody, Chimeric Antigen Receptor, Immune Checkpoint, and Natural Killer

Recently, due to the application of hematopoietic stem cell transplantation and small molecule inhibitor, the survival of acute leukemia is prolonged. However, the 5 year survival rate remains low due to a high incidence of relapse. Immunotherapy is expected to improve the prognosis of patients with relapsed or refractory hematological malignancies because it does not rely on the cytotoxic mechanisms of conventional therapy. In this paper, the advances of immunotherapy in acute leukemia are reviewed from the aspects of Antibody including Unconjugated antibodies, Antibody-drug conjugate and Bispecific antibody, Chimeric Antigen Receptor (CARs), Immune checkpoint, Natural killer cells. The immunological features, mechanisms and limitation in clinic will be described.

Treatment of Adult Patients with Relapsed/Refractory B-Cell Philadelphia-Negative Acute Lymphoblastic Leukemia

The majority of adult patients affected by B-cell acute lymphoblastic leukemia (B-ALL) will relapse after an initial response, while approximately 20% will display primary resistant disease. Patients suffering from relapsed/refractory B-ALL have a very poor outcome. Allogeneic hematopoietic cell transplantation (HCT) still represents the only curative approach, but is not so frequently feasible, because of patient's fitness, donor availability, and the ability to achieve a remission prior to HCT. The estimated remission rates with conventional cytotoxic agents are around 30%, but they are short-lived. These disappointing results led to the introduction of new immunologic-based treatments-blinatumomab and inotuzumab. They produced a substantial improvement in terms of response rates, with the ability, in most cases, to induce a minimal residual disease (MRD)-negative status. Similarly, T cells engineered to express a CD19-specific chimeric antigen receptor (CAR-T) have yielded sensational results among patients with relapsed/refractory B-ALL, with unexpectedly high MRD-negative complete remissions rates. However, the first studies looking at long-term outcomes after CAR-T infusions told us that a significant fraction of such responses are not durable, and may benefit from a consolidation approach such as an allogeneic HCT.

Novel monoclonal antibody-based treatment strategies in adults with acute lymphoblastic leukemia

Adult acute lymphoblastic leukemia (ALL) has a poor overall survival compared with pediatric ALL where cure rates are observed in more than 90% of patients. The recent development of novel monoclonal antibodies targeting CD20, CD19, and CD22 has changed the long-term outcome of this disease, both in the frontline setting (e.g. rituximab) and for patients with relapsed/refractory disease (e.g. inotuzumab ozogamicin and blinatumomab). The CD3-CD19 bispecific T-cell-engaging antibody blinatumomab is also the first drug approved in ALL for patients with persistent or recurrent measurable residual disease, providing a new treatment paradigm for these patients. Several new agents are also in development that use novel constructs or target alternative surface epitopes such as CD123, CD25, and CD38. Herein, we review the role of monoclonal antibodies in adult ALL and summarize the current and future approaches in ALL, including novel combination therapies and the possibility of early incorporation of these agents into treatment regimens.

Novel Therapies in Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

Treatment options for patients with acute lymphoblastic leukemia (ALL) beyond standard chemotherapy have grown significantly in recent years. In this review, we highlight new targeted therapies in ALL, with an emphasis on immunotherapy.

RECENT FINDINGS

Major advances include antibody-based therapies, such as naked monoclonal antibodies, antibody-drug conjugates and bispecific T cell engaging (BiTE) antibodies, as well as adoptive cellular therapies such as chimeric antigen receptor (CAR) T cells. Apart from the above immunotherapeutic approaches, other targeted therapies are being employed in Philadelphia chromosome-positive (Ph+) ALL, Philadelphia-like (Ph-like) ALL, and T cell ALL. These new treatment strategies are changing the treatment landscape of ALL and challenging the current standard of care. Clinical trials will hopefully help determine how to best incorporate these novel therapies into existing treatment algorithms.

Advances in biology of acute lymphoblastic leukemia (ALL) and therapeutic implications

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer and also occurs in adults. Although the outcomes of multi-agent chemotherapy regimens have greatly improved, high toxicity and relapses in many patients necessitate the development of novel therapeutic approaches. Advances in molecular profiling and cytogenetics have identified a broad range of genetic abnormalities, including gene mutations, chromosome translocations and aneuploidy, which has provided a more comprehensive understanding of the biology and pathogenesis of ALL. This understanding has also led to new targeted therapeutic approaches, including the use of selective small molecule inhibitors, nucleic acid-based therapies and immune-based therapies mediated by specific monoclonal antibodies and cellular immunotherapy, which are poised to revolutionize the treatment of various ALL subtypes. The main focus of this review is to highlight the latest advances in ALL biology, including the identification of prognostic factors and putative therapeutic targets. We also review the current status of, and ongoing progress in, the development of targeted therapies for ALL.

Antibody-based therapies in patients with acute lymphoblastic leukemia

The use of multiagent combination chemotherapy regimens results in cure rates of >90% for children and ∼40% for adults with acute lymphoblastic leukemia (ALL) but is associated with extensive toxicity and disappointingly low efficacy in relapsed patients. ALL blast cells express several surface antigens, including CD20, CD22, and CD19, which represent valuable targets for immunotherapy. Monoclonal antibodies, antibody-drug conjugates, and bispecific T-cell-engaging antibodies targeting these antigens offer novel mechanisms of action. Within the last several years, the anti-CD20 antibody rituximab has been added to chemotherapy for newly diagnosed patients <60 years with CD20+ pre-B ALL and significantly improved the 2-year event-free survival from 52% to 65%. In adults with relapsed or refractory CD22+ ALL, the antibody-drug conjugate inotuzumab ozogamicin resulted in a complete response rate of 81% and median overall survival of 7.7 months with reduced toxicity compared with standard chemotherapy. Similarly, the bispecific T-cell-engaging antibody blinatumomab yielded a complete response rate of 44% and a median overall survival of 7.7 months in an extensively treated ALL population. Moreover, ∼80% of ALL patients in complete remission with evidence of minimal residual disease (MRD) achieved a complete MRD response following treatment with blinatumomab. These results highlight the tremendous promise of antibody-based treatment approaches for ALL. Ongoing and future research is critical to further define the role of the various immunotherapies in the frontline treatment of ALL. Additional challenges include the optimal sequencing of the available antibodies in the relapsed setting as well as their integration with stem cell transplant and chimeric antigen receptor T-cell therapy.

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.

Comparable outcomes of patients eligible vs ineligible for SWOG leukemia studies

Patients may be deemed ineligible for a clinical trial for reasons that do not directly impact efficacy or safety. We identified reasons for ineligibility and compared outcomes of ineligible with eligible patients treated on Southwest Oncology Group (SWOG) Leukemia Committee protocols. Patients enrolled in SWOG phase 2, 2/3, or 3 protocols open since 2005 were analyzed for eligibility status, reasons for ineligibility, baseline characteristics, Eastern Cooperative Oncology Group (ECOG) performance status (PS), serious adverse events (SAEs), complete remission (CR) status, and overall survival. A total of 2361 patients were enrolled in the 13 included studies. Of these, 247 (10%) were deemed ineligible; 78 were excluded from analyses, and 169 were included. Of the 169 included in analyses, 60% (101/169) were excluded due to missing baseline documentation. Baseline characteristics comparing ineligible to eligible patients were similar, with the exception of ECOG PS for S0325 (P = .02) and S0530 (P = .002). In multivariable analyses, neither the proportion of patients with ECOG PS ≥ 2 (P = .12) nor the rate of grade 5 SAEs (P = .62) differed between groups. There was no difference in survival between eligible and ineligible patients (P = .25), and CR rates were similar, with the exception of S0325 (P < .001) and S0703 (P = .004). The findings of this study suggest that nonessential eligibility criteria can be less restrictive, thus expanding patient enrollment and avoiding protocol deviations. The clinical trials included in this study were registered at www.clincialtrials.gov as #NCT00085709, #NCT00066794, #NCT00070499, #NCT00109837, #NCT00093418, #NCT00492856, #NCT00337168, #NCT00352365, #NCT00658814, #NCT00792948, #NCT00945815, #NCT00840177, and #NCT01522976.

Novel Therapeutic Strategies in Acute Lymphoblastic Leukemia

Chemotherapy cures only a minority of adult patients with acute lymphoblastic leukemia (ALL). In addition, relapsed ALL has a poor outcome with 5-year survival as low as 7 %. Hence, there is a need to develop effective therapies to treat relapsed disease and to combine these agents with chemotherapy to improve outcomes in newly diagnosed patients. ALL cells express several antigens amenable to target therapies including CD19, CD20, CD22, and CD52. Over the last decade, there has been a surge in the development of immune therapies which target these receptors and that have induced robust responses. In this manuscript, we review these novel immune agents in the treatment of B-ALL. As these new therapies mature, the challenge going forward will be to find safe and effective combinations of these agents with chemotherapy and to determine their place in the current treatment schema.

Novel immunotherapies for adult patients with B-lineage acute lymphoblastic leukemia

The past decade witnessed the rapid development of adult B-lineage acute lymphoblastic leukemia (ALL) treatment. Beyond the development of chemotherapy regimens, immunotherapy is starting a new era with unprecedented complete remission (CR) rate. Targeting B-lineage-specific surface markers such as CD19, CD20, CD22, or CD52, immunotherapy has been demonstrating promising clinical results. Among the immunotherapeutic methods, naked monoclonal antibodies (mAbs), antibody-drug conjugate (ADC), bispecific T cell engager (BiTE), and chimeric antigen receptor (CAR) T cells are the main types. In this review, we will examine the emerging preclinical and clinical development on (1) anti-CD20 naked mAbs rituximab, ofatumumab, and obinutuzumab; (2) anti-CD19 ADCs SAR3419 and SGN-CD19A and anti-CD19 BiTE blinatumomab; (3) anti-CD22 naked mAb epratuzumab and anti-CD22 ADC inotuzumab ozogamicin; (4) anti-CD52 naked mAb alemtuzumab; and (5) anti-CD19 CAR T cells. We will discuss their efficacy, adverse effects, as well as future development.

Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia in Adults

Patients with relapsed and refractory acute lymphoblastic leukemia (ALL) have a dismal prognosis with less than 10 % of patients surviving 5 years. Most such patients cannot be rescued with currently available therapies, whatever the initial treatment they receive. Therefore, there is an urgent need for novel treatment options. Fortunately, over the past several years, an improved understanding of the biology of the disease has allowed the identification of rational molecular targets for therapeutic endeavors and the emergence of novel therapies has sparked great interest. This review will discuss the current treatment landscape for adult patients with relapsed and/or refractory ALL.

How should we treat a patient with relapsed Ph-negative B-ALL and what novel approaches are being investigated?

Despite significant improvements in outcome of newly diagnosed B-precursor ALL, the results in relapsed or refractory adult ALL are overall poor. Large retrospective studies revealed significant differences in terms of outcome, with particularly poor response rates in early or refractory relapses, whereas late relapses usually respond very well to repeated standard induction. Particularly new immunotherapy compounds like the CD19 bispecific antibody Blinatumomab and the conjugated CD22 antibody Inotuzumab yielded promising response rates compared to standard therapies in randomised trials. Long-term survival is however still poor. The optimal use of these compounds remains to be defined. Chimeric antigen receptor T-cells are another promising treatment approach and multicenter clinical trials in adult ALL are awaited. For selected patients molecular directed therapies may have a role in relapsed ALL; standard diagnostic algorithms need to be defined. One of the major challenges is to define the role of stem cell transplantation after relapse. Whereas this procedure appears to be the only chance for cure, the mortality and relapse rate are still high and optimisation is urgently needed. Future strategies include optimised use of new compounds as part of combination regimens and the earlier treatment of upcoming relapse in the situation of persistent or recurrent minimal residual disease.

Acute lymphoblastic leukemia: a comprehensive review and 2017 update

Acute lymphoblastic leukemia (ALL) is the second most common acute leukemia in adults, with an incidence of over 6500 cases per year in the United States alone. The hallmark of ALL is chromosomal abnormalities and genetic alterations involved in differentiation and proliferation of lymphoid precursor cells. In adults, 75% of cases develop from precursors of the B-cell lineage, with the remainder of cases consisting of malignant T-cell precursors. Traditionally, risk stratification has been based on clinical factors such age, white blood cell count and response to chemotherapy; however, the identification of recurrent genetic alterations has helped refine individual prognosis and guide management. Despite advances in management, the backbone of therapy remains multi-agent chemotherapy with vincristine, corticosteroids and an anthracycline with allogeneic stem cell transplantation for eligible candidates. Elderly patients are often unable to tolerate such regimens and carry a particularly poor prognosis. Here, we review the major recent advances in the treatment of ALL.

Novel therapy for childhood acute lymphoblastic leukemia

INTRODUCTION

During recent decades, the prognosis of childhood acute lymphoblastic leukemia (ALL) has improved dramatically, nowadays, reaching a cure rate of almost 90%. These results are due to a better management and combination of old therapies, refined risk-group stratification and emergence of minimal residual disease (MRD) combined with treatment's intensification for high-risk subgroups. However, the subgroup of patients with refractory/relapsed ALL still presents a dismal prognosis indicating necessity for innovative therapeutic approaches. Areas covered: We performed an exhaustive review of current first-line therapies for childhood ALL in the worldwide main consortia, summarized the major advances for front-line and relapse treatment and highlighted recent and promising innovative therapies with an overview of the most promising ongoing clinical trials. Expert opinion: Two major avenues marked the beginning of 21^st century. First, is the introduction of tyrosine-kinase inhibitor coupled to chemotherapy for treatment of Philadelphia positive ALL opening new treatment possibilities for the recently identified subgroup of Ph-like ALL. Second, is the breakthrough of immunotherapy, notably CAR T-cell and specific antibody-based therapy, with remarkable success observed in initial studies. This review gives an insight on current knowledge in these innovative therapeutic directions, summarizes currently ongoing clinical trials and addresses challenges these approaches are faced with.

Antibody Based Therapies in Acute Leukemia

Despite great progress in the curative treatment of acute leukemia, outcomes for those with relapsed and/or chemotherapy-refractory disease remain poor. Current intensive cytotoxic therapies can be associated with significant morbidity and novel therapies are needed to improve outcomes. Immunotherapy based approaches provide an alternative mechanism of action in the treatment of acute leukemia. Due to cell surface antigen expression, leukemia in particular is amenable to targeted therapies, such as antibody-based therapy. Based on the potential for non-overlapping toxicity, the possibility of synergistic action with standard chemotherapy, and by providing a novel method to overcome chemotherapy resistance, antibody-based therapies have shown potential for benefit. Modifications to standard monoclonal antibodies, including drug conjugation and linkage to T-cells, may further enhance efficacy of antibody-based therapies. Identifying the ideal timing for incorporation of antibody-based therapies, within standard regimens, may lead to improvement in overall outcomes. This article will provide an overview of antibody-based therapies in clinical development for the treatment of acute leukemia in children and adults, with a particular focus on the current strategies and future developments.

The Society for Immunotherapy of Cancer consensus statement on immunotherapy for the treatment of hematologic malignancies: multiple myeloma, lymphoma, and acute leukemia

Increasing knowledge concerning the biology of hematologic malignancies as well as the role of the immune system in the control of these diseases has led to the development and approval of immunotherapies that are resulting in impressive clinical responses. Therefore, the Society for Immunotherapy of Cancer (SITC) convened a hematologic malignancy Cancer Immunotherapy Guidelines panel consisting of physicians, nurses, patient advocates, and patients to develop consensus recommendations for the clinical application of immunotherapy for patients with multiple myeloma, lymphoma, and acute leukemia. These recommendations were developed following the previously established process based on the Institute of Medicine's clinical practice guidelines. In doing so, a systematic literature search was performed for high-impact studies from 2004 to 2014 and was supplemented with further literature as identified by the panel. The consensus panel met in December of 2014 with the goal to generate consensus recommendations for the clinical use of immunotherapy in patients with hematologic malignancies. During this meeting, consensus panel voting along with discussion were used to rate and review the strength of the supporting evidence from the literature search. These consensus recommendations focus on issues related to patient selection, toxicity management, clinical endpoints, and the sequencing or combination of therapies. Overall, immunotherapy is rapidly emerging as an effective therapeutic strategy for the management of hematologic malignances. Evidence-based consensus recommendations for its clinical application are provided and will be updated as the field evolves.

Treating adults with acute lymphocytic leukemia: new pharmacotherapy options

INTRODUCTION

Advances in acute lymphocytic leukemia (ALL) therapy has led to long-term survival rates in children. However, only 30%-40% of adults achieve long-term disease-free survival. After relapse, the outcome of salvage chemotherapy is very disappointing with less than 10% of long survival. Novel agents are therefore desperately required to improve response rates and survival, but also the quality of life of patients. Areas covered: The following review is a comprehensive summary of various novel options reported over the past few years in the therapeutic area of adult ALL. Expert opinion: Identifying key components involved in disease pathogenesis may lead to new approaches. In a near future, the incorporation of monoclonal antibodies and T-cell directed approaches including blinatumomab and chimeric antigen receptor T cells may increase the cure rates and may reduce the need for intensive therapy.

Recent advances and novel treatment paradigms in acute lymphocytic leukemia

This is an exciting time in the treatment of acute lymphoblastic leukemia (ALL) given the advances in the relapsed/refractory setting. The development of antibody treatments (including antibody drug conjugates with toxins) offers a different treatment approach compared with conventional chemotherapy regimens. Moreover, the use of bispecific T-cell-engager antibodies (BiTEs) such as blinatumomab harness the cytotoxic activity of T cells against CD19-positive lymphoblasts. Another strategy involves the use of chimeric antigen receptor (CAR) T cells. CAR T cells have demonstrated promising results in the relapsed/refractory setting. However, the use of BiTEs and CAR T cells is also associated with a distinct set of adverse reactions that must be taken into account by the treating physician. Apart from the above strategies, the use of other targeted therapies has attracted interest. Namely, the discovery of the Philadelphia (Ph)-like signature in children and young adults with ALL has led to the use of tyrosine kinase inhibitors (TKI) in these patients. The different drugs and strategies that are being tested in the relapsed/refractory ALL setting pose a unique challenge in identifying the optimum sequence of treatment and determining which approaches should be considered for frontline treatment.

Novel cancer antigens for personalized immunotherapies: latest evidence and clinical potential

The clinical success of monoclonal antibody immune checkpoint modulators such as ipilimumab, which targets cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and the recently approved agents nivolumab and pembrolizumab, which target programmed cell death receptor 1 (PD-1), has stimulated renewed enthusiasm for anticancer immunotherapy, which was heralded by Science as 'Breakthrough of the Year' in 2013. As the potential of cancer immunotherapy has been recognized since the 1890s when William Coley showed that bacterial products could be beneficial in cancer patients, leveraging the immune system in the treatment of cancer is certainly not a new concept; however, earlier attempts to develop effective therapeutic vaccines and antibodies against solid tumors, for example, melanoma, frequently met with failure due in part to self-tolerance and the development of an immunosuppressive tumor microenvironment. Increased knowledge of the mechanisms through which cancer evades the immune system and the identification of tumor-associated antigens (TAAs) and negative immune checkpoint regulators have led to the development of vaccines and monoclonal antibodies targeting specific tumor antigens and immune checkpoints such as CTLA-4 and PD-1. This review first discusses the established targets of currently approved cancer immunotherapies and then focuses on investigational cancer antigens and their clinical potential. Because of the highly heterogeneous nature of tumors, effective anticancer immunotherapy-based treatment regimens will likely require a personalized combination of therapeutic vaccines, antibodies and chemotherapy that fit the specific biology of a patient's disease.

Extensive crosslinking of CD22 by epratuzumab triggers BCR signaling and caspase-dependent apoptosis in human lymphoma cells

Epratuzumab has demonstrated therapeutic activity in patients with non-Hodgkin lymphoma, acute lymphoblastic leukemia, systemic lupus erythematosus, and Sjögren's syndrome, but its mechanism of affecting normal and malignant B cells remains incompletely understood. We reported previously that epratuzumab displayed in vitro cytotoxicity to CD22-expressing Burkitt lymphoma cell lines (Daudi and Ramos) only when immobilized on plates or combined with a crosslinking antibody plus a suboptimal amount of anti-IgM (1 μg/mL). Herein, we show that, in the absence of additional anti-IgM ligation, extensive crosslinking of CD22 by plate-immobilized epratuzumab induced intracellular changes in Daudi cells similar to ligating B-cell antigen receptor with a sufficiently high amount of anti-IgM (10 μg/mL). Specifically, either treatment led to phosphorylation of CD22, CD79a and CD79b, along with their translocation to lipid rafts, both of which were essential for effecting caspase-dependent apoptosis. Moreover, such immobilization induced stabilization of F-actin, phosphorylation of Lyn, ERKs and JNKs, generation of reactive oxygen species (ROS), decrease in mitochondria membrane potential (Δψ_m), upregulation of pro-apoptotic Bax, and downregulation of anti-apoptotic Bcl-xl and Mcl-1. The physiological relevance of immobilized epratuzumab was implicated by noting that several of its in vitro effects, including apoptosis, drop in Δψ_m, and generation of ROS, could be observed with soluble epratuzumab in Daudi cells co-cultivated with human umbilical vein endothelial cells. These results suggest that the in vivo mechanism of non-ligand-blocking epratuzumab may, in part, involve the unmasking of CD22 to facilitate the trans-interaction of B cells with vascular endothelium.

Blinatumomab for the Treatment of Philadelphia Chromosome-Negative, Precursor B-cell Acute Lymphoblastic Leukemia

Blinatumomab is a CD19/CD3 bispescific antibody designed to redirect T cells toward malignant B cells and induce their lysis. It recently gained accelerated approval by the FDA for the treatment of relapsed or refractory Philadelphia chromosome-negative B-cell acute lymphoblastic leukemia (RR-ALL). In the phase II trial that served as the basis for approval, blinatumomab demonstrated significant single-agent activity and induced remission [complete remission (CR) and CR with incomplete recovery of peripheral blood counts (CRh)] in 43% of 189 adult patients with RR-ALL; the majority of responders (82%) also attained negative minimal residual disease (MRD(-)) status that did not generally translate into long-term remissions in most cases. Additional studies show that blinatumomab can induce high response rates associated with lasting remissions in patients in first remission treated for MRD positivity, suggesting a role for blinatumomab in the upfront, MRD-positive setting. Blinatumomab infusion follows a predictable immunopharmacologic profile, including early cytokine release that can be associated with a clinical syndrome, T-cell expansion, and B-cell depletion. Neurologic toxicities represent a unique toxicity that shares similarities with adverse effects of other T-cell engaging therapies. Further studies are needed to clarify the optimal disease setting and timing for blinatumomab therapy. Additional insights into the pathogenesis, risk factors, and prevention of neurologic toxicities as well as a better understanding of the clinical consequences and biologic pathways that are associated with drug resistance are needed.

Re-induction chemoimmunotherapy with epratuzumab in relapsed acute lymphoblastic leukemia (ALL): Phase II results from Children's Oncology Group (COG) study ADVL04P2

BACKGROUND

Given the success of immunotherapeutic approaches in hematologic malignancies, the COG designed a phase I/II study to determine whether the addition of epratuzumab (anti-CD22) to an established chemotherapy platform improves rates of second remission (CR2) in pediatric patients with B-lymphoblastic leukemia (B-ALL) and early bone marrow relapse.

PROCEDURE

Therapy consisted of three established blocks of re-induction chemotherapy. Epratuzumab (360 mg/m(2)/dose) was combined with chemotherapy on weekly × 4 (B1) and twice weekly × 4 [eight doses] (B2) schedules during the first re-induction block. Remission rates and minimal residual disease (MRD) status were compared to historical rates observed with the identical chemotherapy platform alone.

RESULTS

CR2 was achieved in 65 and 66%, of the evaluable B1 (n = 54) and B2 patients (n = 60), respectively; unchanged from that observed historically without epratuzumab. Rates of MRD negativity (<0.01%) were 31% in B1 (P = 0.4128) and 39% in B2 patients (P = 0.1731), compared to 25% in historical controls. The addition of epratuzumab was well tolerated, with a similar toxicity profile to that observed with the re-induction chemotherapy platform regimen alone.

CONCLUSIONS

Epratuzumab was well tolerated in combination with re-induction chemotherapy. While CR2 rates were not improved compared to historical controls treated with chemotherapy alone, there was a non-significant trend towards improvement in MRD response with the addition of epratuzumab (twice weekly for eight doses) to re-induction chemotherapy.

Structure, development, preclinical and clinical efficacy of blinatumomab in acute lymphoblastic leukemia

ABSTRACT 

The treatment of acute lymphoblastic leukemia (ALL) in adults remains challenging and novel therapies are needed. The antigen, CD19, is expressed by >90% of pre-B ALLs and represents an attractive therapeutic target. The bispecific T-cell-engaging antibody, blinatumomab, targets CD19 and has demonstrated encouraging results in minimal residual disease positive and relapsed/refractory pre-B ALL. In this review, we discuss in detail the mechanism of action and key pharmacologic aspects of blinatumomab. In addition, the preclinical studies, clinical studies and toxicities are summarized.

Monoclonal antibodies in acute lymphoblastic leukemia

With modern intensive combination polychemotherapy, the complete response (CR) rate in adults with acute lymphoblastic leukemia (ALL) is 80% to 90%, and the cure rate is 40% to 50%. Hence, there is a need to develop effective salvage therapies and combine novel agents with standard effective chemotherapy. ALL leukemic cells express several surface antigens amenable to target therapies, including CD20, CD22, and CD19. Monoclonal antibodies target these leukemic surface antigens selectively and minimize off-target toxicity. When added to frontline chemotherapy, rituximab, an antibody directed against CD20, increases cure rates of adults with Burkitt leukemia from 40% to 80% and those with pre-B ALL from 35% to 50%. Inotuzumab ozogamicin, a CD22 monoclonal antibody bound to calicheamicin, has resulted in marrow CR rates of 55% and a median survival of 6 to 7 months when given to patients with refractory-relapsed ALL. Blinatumomab, a biallelic T cell engaging the CD3-CD19 monoclonal antibody, also resulted in overall response rates of 40% to 50% and a median survival of 6.5 months in a similar refractory-relapsed population. Other promising monoclonal antibodies targeting CD20 (ofatumumab and obinutuzumab) or CD19 or CD20 and bound to different cytotoxins or immunotoxins are under development. Combined modalities of chemotherapy and the novel monoclonal antibodies are under investigation.

How I treat adults with relapsed or refractory Philadelphia chromosome-negative acute lymphoblastic leukemia

The long-term prognosis of adult patients with relapsed Philadelphia chromosome-negative acute lymphoblastic lymphoma (ALL) is poor. Allogeneic stem cell transplant in second remission is the only curative approach and is the goal when feasible. There is no standard chemotherapy regimen for relapsed disease, although a few agents are approved for use in this setting. The bispecific CD19-directed CD3 T-cell engager, blinatumomab, has recently been granted accelerated approval by the US Food and Drug Administration for relapsed or refractory disease of B-cell lineage. For patients with relapsed T-cell ALL, nelarabine is available. Liposomal vincristine is also approved for relapsed disease. When selecting combination chemotherapy salvage options, evaluation of the prior treatment and timing of relapse informs treatment decisions. Monoclonal and cellular investigational therapies are quite promising and should be explored in the appropriate patient.