Safety and Efficacy of Blinatumomab in Combination With a Tyrosine Kinase Inhibitor for the Treatment of Relapsed Philadelphia Chromosome-positive Leukemia

Therapeutic Strategies for Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia in Adult Patients: Optimizing the Use of Monoclonal Antibodies

The treatment landscape for relapsed or refractory acute lymphoblastic leukemia (RR ALL) has evolved significantly with the introduction of monoclonal antibodies such as blinatumomab and inotuzumab ozogamicin. These agents have demonstrated remarkable efficacy, achieving high response rates and minimal residual disease (MRD) negativity. However, the optimal selection, sequencing, and integration of monoclonal antibodies and other modalities like standard chemotherapy or chimeric antigen receptor T-cell therapy remain areas of active investigation. The absence of direct comparative studies has led to reliance on indirect analyses, which provide conflicting results regarding the relative benefits of inotuzumab and blinatumomab. While inotuzumab is preferred in high-disease-burden settings due to its cytoreductive capabilities, blinatumomab shows superior performance in low-disease-burden settings by leveraging preserved T-cell function. Sequential and combination approaches, such as induction with inotuzumab followed by blinatumomab consolidation, may optimize outcomes, particularly for patients undergoing subsequent allogeneic stem cell transplantation (alloSCT). The interval between inotuzumab and alloSCT is critical to mitigate the risk of veno-occlusive disease (VOD). Despite these advances, the prognosis for patients with high-risk genetic lesions, such as TP53 mutations, remains poor, underscoring the need for innovative therapeutic strategies. As monoclonal antibodies increasingly move into frontline therapy, their role in relapse settings must be redefined. Future research should focus on unraveling the molecular underpinnings of resistance and refining treatment paradigms to improve survival and quality of life for patients with RR ALL.

Treatment of Older Patients With ALL

Older patients with ALL often have high-risk disease characterized by adverse-risk cytogenetic and molecular abnormalities, as well as Philadelphia chromosome (Ph)-positive and Ph-like phenotypes. They often have comorbidities resulting in poor tolerance to chemotherapy and are at risk of developing therapy-related myeloid neoplasms (t-MNs). In Ph-negative ALL, the duration and intensity of chemotherapy was reduced, and outcomes improved with the addition of inotuzumab ozogamicin (InO) and blinatumomab into the frontline setting. However, t-MNs are still being observed, prompting the development of chemotherapy-free regimens with InO and blinatumomab as well as chimeric antigen receptor (CAR) T-cell therapies in high-risk disease. In Ph-positive ALL, chemotherapy and allogeneic hematopoietic stem-cell transplantation (HSCT) were historically considered a standard of care. However, the introduction of blinatumomab and newer-generation BCR::ABL1 tyrosine kinase inhibitors (TKIs) into the frontline setting significantly improved outcomes. The combination of blinatumomab and ponatinib induced high rates of complete molecular responses and excellent survival, without reliance on HSCT. A subset of patients with elevated WBC count at diagnosis are at particular risk of CNS and systemic relapse and may require additional strategies such as incorporating one to two cycles of high-dose methotrexate/cytarabine into consolidation, and potentially CAR T cells. In T-cell ALL, adding venetoclax into the frontline setting has improved outcomes. In early T-cell precursor ALL, HSCT is still needed. To further improve outcomes in older patients, novel agents such as subcutaneous blinatumomab, CAR T cells, newer-generation TKIs, and menin inhibitors should be investigated in the frontline setting.

The evolving therapeutic revolution in adult acute lymphoblastic leukemia

The past decade has witnessed remarkable advances in deciphering the pathophysiology of acute lymphoblastic leukemia (ALL) and in developing novel targeted therapies. Basic research and genomic mapping have identified new prognostic biomarkers, targets, and ALL subtypes (e.g., Philadelphia-like ALL). The ongoing therapeutic revolution in ALL is driven by the addition to the treatment arsenal of therapies that target the ABL fusions, like the BCR::ABL1 tyrosine kinase inhibitors, as well as novel agents that target CD19 and CD22: the CD22 antibody-drug conjugate inotuzumab ozogamicin, the bispecific CD3/CD19 T-cell engager antibody blinatumomab, and CD19 chimeric antigen receptor T-cell therapies. These combinations have improved the long-term survival rates in B-cell ALL to 70%, and in Philadelphia chromosome-positive ALL to 80%-90%. The desired goals are to achieve cure rates comparable to those in pediatric ALL and to reduce or eliminate the need for prolonged intensive/maintenance chemotherapy and associated toxicities.

Frontline immunotherapeutic combination strategies in adult B-cell acute lymphoblastic leukemia: reducing chemotherapy intensity and toxicity and harnessing efficacy

Using immunotherapeutic agents like inotuzumab ozogamicin (InO), blinatumomab, or chimeric antigen receptor T (CAR T)-cell therapy in frontline adult B-cell acute lymphoblastic leukemia (B-ALL) therapy is promising. These agents are mostly well tolerated and have different toxicity profiles than conventional chemotherapy, enabling their combination with chemotherapy. Additionally, they have often been shown to overcome the traditional adverse ALL risk features. Recently blinatumomab was approved as part of consolidation therapy in MRD negative B-ALL; however, a significant proportion of patients had progressed or relapsed before reaching the timepoint of blinatumomab administration. Including InO/blinatumomab from induction onwards could induce earlier and deeper remissions. Modifications of dosing and administration schedules, as with the fractionated InO schedule with low-intensity chemotherapy, and subcutaneous blinatumomab, appear to reduce the toxicity and improve the anti-ALL efficacy. CAR T-cell therapies like brexucabtagene autoleucel as a consolidation approach have shown positive outcomes. The feasibility of using CAR T-cells to reduce the need for long-drawn maintenance and the need for allogeneic hematopoietic stem cell transplantation (HSCT) are questions of ongoing clinical trials. Newer generation CAR T-cell products like obecabtagene autoleucel appear as effective and safer. Better disease monitoring through next generation sequencing based measurable residual disease analysis could identify patients where treatment intensification including HSCT, or deintensification, is suitable.

How I treat Philadelphia chromosome-like acute lymphoblastic leukemia in children, adolescents, and young adults

ABSTRACT

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) represents a high-risk B-lineage ALL subtype characterized by adverse clinical features and poor relapse-free survival despite risk-adapted multiagent chemotherapy regimens. The advent of next-generation sequencing has unraveled the diversity of kinase-activating genetic drivers in Ph-like ALL that are potentially amenable to personalized molecularly-targeted therapies. Based upon robust preclinical data and promising case series of clinical activity of tyrosine kinase inhibitor (TKI)-based treatment in adults and children with relevant genetic Ph-like ALL subtypes, several clinical trials have investigated the efficacy of JAK- or ABL-directed TKIs in cytokine receptor-like factor 2 (CRLF2)/JAK pathway-mutant or ABL-class Ph-like ALL, respectively. The final results of these trials are pending, and standard-of-care therapeutic approaches for patients with Ph-like ALL have yet to be defined. In this How I Treat perspective, we review recent literature to guide current evidence-based treatment recommendations via illustrative clinical vignettes of children, adolescents, and young adults with newly diagnosed or relapsed/refractory Ph-like ALL, and we further highlight open and soon-to-open trials investigating immunotherapy and TKIs specifically for this high-risk patient population.

Frontline treatment of adults with newly diagnosed B-cell acute lymphoblastic leukaemia

In the past decade, there has been considerable progress in the treatment of adults with newly diagnosed B-cell acute lymphoblastic leukaemia. This evolution is the product of a more profound understanding of acute lymphoblastic leukaemia biology, innovations in measurable residual disease quantification that led to precise disease-risk stratification, adoption of contemporary paediatric-inspired regimens, inclusion of tyrosine kinase inhibitors in the treatment of Philadelphia chromosome-positive acute lymphoblastic leukaemia, and the introduction of immunotherapy in the frontline setting. Nevertheless, outcomes of acute lymphoblastic leukaemia in adults are inferior compared with those of children, with excessive rates of treatment failure, and therapy-related morbidity and mortality. Simultaneously, transplant consolidation has continued to be used frequently for high-risk adults with acute lymphoblastic leukaemia in first complete remission. Considering the rapid pace of evolution in acute lymphoblastic leukaemia management, novel trial designs are warranted to accelerate advancements and streamline approaches. Here, we summarise progress in the treatment of adults with newly diagnosed acute lymphoblastic leukaemia, which adds to previously published guidelines by focusing specifically on first-line decisions for B-cell acute lymphoblastic leukaemia and how to best personalise treatment. This Viewpoint also includes experiences with regimens and testing approaches currently available not only in Europe, but also on multiple continents with different practices and resources.

Advances in the treatment of adults with newly diagnosed B-cell acute lymphoblastic leukemia: the role of frontline immunotherapy-based regimens

Blinatumomab and inotuzumab ozogamicin (INO) are both active in relapsed/refractory B-cell acute lymphoblastic leukemia (ALL) and improve outcomes compared with conventional chemotherapy in this setting. Several prospective clinical trials have explored the use of these agents in adults with newly diagnosed B-cell ALL, with promising outcomes observed in younger and older adults and in both Philadelphia chromosome (Ph)-positive and Ph-negative ALL. These novel regimens result in high rates of deep measurable residual disease (MRD) negativity and may improve survival compared with chemotherapy-only approaches, allowing for less reliance on intensive chemotherapy and allogeneic hematopoietic stem cell transplantation (HSCT). This review discusses novel approaches to integrating INO and/or blinatumomab into frontline ALL regimens, including the potential role of chemotherapy-free regimens in some subgroups. The role of MRD monitoring is also discussed, including how this can inform decisions for consolidative allogeneic HSCT or investigational approaches with CD19 CAR T-cells.

MRD in Philadelphia Chromosome-Positive ALL: Methodologies and Clinical Implications

PURPOSE OF REVIEW

Measurable residual disease (MRD) is integral in the management of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). This review discusses the current methods used to evaluate MRD as well as the interpretation, significance, and incorporation of MRD in current practice.

RECENT FINDINGS

New molecular technologies have allowed the detection of MRD to levels as low as 10- 6. The most used techniques to evaluate MRD are multiparametric flow cytometry (MFC), quantitative reverse transcription polymerase chain reaction (RT-qPCR), and high-throughput next-generation sequencing (NGS). Each method varies in terms of advantages, disadvantages, and MRD sensitivity. MRD negativity after induction treatment and after allogeneic hematopoietic cell transplantation (HCT) is an important prognostic marker that has consistently been shown to be associated with improved outcomes. Blinatumomab, a new targeted therapy for Ph + ALL, demonstrates high efficacy in eradicating MRD and improving patient outcomes. In the relapsed/refractory setting, the use of inotuzumab ozogamicin and tisagenlecleucel has shown promise in eradicating MRD. The presence of MRD has become an important predictive measure in Ph + ALL. Current studies evaluate the use of MRD in treatment decisions, especially in expanding therapeutic options for Ph + ALL, including tyrosine kinase inhibitors, targeted antibody therapies, chimeric antigen receptor cell therapy, and HCT.

SOHO State of the Art Updates and Next Questions | Next Questions: Acute Lymphoblastic Leukemia

The integration of immune and targeted therapies into the treatment of acute lymphoblastic leukemia (ALL) has significantly improved outcomes, reduced the intensity and duration of chemotherapy, and the reliance on allogeneic stem cell transplantation (SCT). In younger patients with Philadelphia chromosome (Ph)-negative ALL, treatment with Hyper-CVAD and blinatumomab +/- inotuzumab has improved the 3-year overall survival (OS) to above 85%. In older patients, using less intensive chemotherapy (mini-Hyper-CVD) in combination with inotuzumab and blinatumomab has improved the 5-year OS rate to 50%. In Ph+ ALL, the chemotherapy-free combinations of blinatumomab and ponatinib (or dasatinib) have become a new standard of care resulting in 3-year OS of 85% to 90%. Because the methotrexate-cytarabine courses were omitted in the nonchemotherapy regimens, central nervous system (CNS) relapses were noted, particularly in patients with a WBC count > 70 × 109/L, requiring to consider increasing the number of prophylactic intrathecals (from 12 to 15) and perhaps developing a CNS risk-directed high-dose systemic chemotherapy. In relapsed/refractory ALL, a dose-dense regimen integrating blinatumomab and inotuzumab with low-intensity chemotherapy followed by consolidation with chimeric antigen receptor T-cell therapy is being investigated. The detection of measurable residual disease (MRD) following ALL therapy is predictive of disease relapse. Using next-generation sequencing allows the detection of MRD at 1 × 10-6 which was shown to be superior to multiparameter flow cytometry and polymerase chain reaction in predicting relapse, and could be used to decide on the duration of therapy or need to change therapy. Herein, we review the recent updates and areas of unmet need in ALL.

SOHO State of the Art Updates and Next Questions: Update on the Approach to Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

The outcome of Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) has improved significantly following the introduction of the BCR::ABL1 tyrosine kinase inhibitors (TKIs). The addition of newer-generation and more potent TKIs resulted in higher rates of molecular responses and better survival. Achieving a complete molecular remission (CMR; disappearance of the BCR::ABL1 transcripts) within the first 3 months of therapy is an important endpoint in newly diagnosed Ph-positive ALL that identifies patients who have an excellent long-term survival and who may not need to receive an allogeneic hematopoietic stem cell transplantation (HSCT) in first complete remission (CR). Chemotherapy-free combinations with blinatumomab plus TKIs showed encouraging results with estimated 2 to 4 year overall survival (OS) rates of 80% to 90%. Treatment with blinatumomab and ponatinib resulted in a CMR rate of 84%, a 2-year event-free survival (EFS) of 78%, and a 2-year OS rate of 90%; only 1 patient underwent HSCT. The detection of measurable residual disease (MRD) is the most important factor predicting for disease relapse. Studies have shown that the next-generation sequencing (NGS) assay is more sensitive than RT-PCR for the detection of MRD in Ph-positive ALL. Approximately 15% to 30% of patients who achieve NGS MRD negativity at a sensitivity of 1 × 10-6 may still have detectable BCR::ABL1 transcripts by RT-PCR. Achieving NGS MRD negativity can also identify patients who may have durable remissions with a low risk of relapse. Herein, we discuss the current approach to the management of adults with Ph-positive ALL, the role of HSCT, MRD monitoring, and future therapies.

Asciminib Maintains Antibody-Dependent Cellular Cytotoxicity against Leukemic Blasts

B cell acute lymphoblastic leukemia (B-ALL) is characterized by an accumulation of malignant precursor cells. Treatment consists of multiagent chemotherapy followed by allogeneic stem cell transplantation in high-risk patients. In addition, patients bearing the BCR-ABL1 fusion gene receive concomitant tyrosine kinase inhibitor (TKI) therapy. On the other hand, monoclonal antibody therapy is increasingly used in both clinical trials and real-world settings. The introduction of rituximab has improved the outcomes in CD20 positive cases. Other monoclonal antibodies, such as tafasitamab (anti-CD19), obinutuzumab (anti-CD20) and epratuzumab (anti-CD22) have been tested in trials (NCT05366218, NCT04920968, NCT00098839). The efficacy of monoclonal antibodies is based, at least in part, on their ability to induce antibody-dependent cellular cytotoxicity (ADCC). Combination treatments, e.g., chemotherapy and TKI, should therefore be screened for potential interference with ADCC. Here, we report on in vitro data using BCR-ABL1 positive and negative B-ALL cell lines treated with rituximab and TKI. NK cell activation, proliferation, degranulation, cytokine release and tumor cell lysis were analyzed. In contrast to ATP site inhibitors such as dasatinib and ponatinib, the novel first-in-class selective allosteric ABL myristoyl pocket (STAMP) inhibitor asciminib did not significantly impact ADCC in our settings. Our results suggest that asciminib should be considered in clinical trials.

Low-Intensity and Chemo-Free Treatments in Ph+ ALL: Progression-Free Survival Based on Indirect Comparisons

In Philadelphia chromosome-positive B-cell (Ph+) acute lymphoblastic leukemia (LLA), growing evidence has accumulated regarding the efficacy of low-intensity and chemo-free regimens. Our objective was to analyze all recent trials evaluating these treatments and to compare them in terms of efficacy. We applied the Shiny method, an artificial intelligence technique, to analyze Kaplan-Meier curves and reconstruct patient-level data. Reconstructed patient data were then evaluated through standard survival statistics and subjected to indirect head-to-head treatment comparisons. The endpoint was progression-free survival (PFS). Based on 432 reconstructed patients, eight trials were analyzed. The survival data from these trials were pooled into three types of treatments: (i) treatments based on tyrosine kinase inhibitors (TKIs) combined with reduced-intensity chemotherapy (denoted as TKICHE); (ii) TKIs associated with steroids with no chemotherapy (TKISTE); (iii) chemotherapy-free combinations of blinatumomab plus TKIs (TKIBLI). According to the Shiny method, the three PFS curves were reported in a single Kaplan-Meier graph and subjected to survival statistics. In terms of PFS, TKIBLI ranked first, TKICHE second, and TKISTE third; the differences between these three regimens were statistically significant. This multi-treatment Kaplan-Meier graph, generated through the Shiny method, summarized the current evidence on these treatments in both qualitative and quantitative terms.

SOHO State of the Art Updates and Next Questions | Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia in Adults: Therapeutic Options and Challenges in 2023

The therapeutic landscape of Philadelphia chromosome positive acute lymphoblastic leukemia (ALL) for adults has dramatically changed over the past 2 decades; the emergence of newer generations of tyrosine kinase inhibitors and incorporation of targeted immunotherapies into front-line therapy have significantly improved outcomes to the point where an argument can be made that this entity may no longer be considered a high-risk ALL subgroup. In this review article, we discuss different front-line regimens (both intensive and deintensified regimens including chemotherapy-free regimens). We also review disease monitoring strategies, discuss the role of allogeneic hematopoietic stem cell transplantation, and discuss the rapidly changing therapeutic landscape for patients with relapsed disease.

SOHO State of the Art Updates and Next Questions | Hyper-CVAD in 2022: Lessons Learned and New Approaches

Combination chemotherapy is the mainstay of treatment for acute lymphoblastic leukemia (ALL). The Hyper-CVAD regimen was developed in 1992 at MD Anderson Cancer Center and has since become a standard of care option for adult patients with ALL. Since its conception, a number of modifications have been implemented to customize the regimen for different patient populations and safely incorporate novel therapies without compromising tolerability. We aim to review the evolution of the Hyper-CVAD regimen over the past 3 decades, focusing on clinical pearls, as well as future directions.

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.

Management of children and adolescents with chronic myeloid leukemia in blast phase: International pediatric CML expert panel recommendations

Treatment of chronic myeloid leukemia has improved significantly with the introduction of tyrosine kinase inhibitors (TKIs), and treatment guidelines based on numerous clinical trials are available for chronic phase disease. However for CML in the blast phase (CML-BP), prognosis remains poor and treatment options are much more limited. The spectrum of treatment strategies for children and adolescents with CML-BP has largely evolved empirically and includes treatment principles derived from adult CML-BP and pediatric acute leukemia. Given this heterogeneity of treatment approaches, we formed an international panel of pediatric CML experts to develop recommendations for consistent therapy in children and adolescents with this high-risk disease based on the current literature and national standards. Recommendations include detailed information on initial diagnosis and treatment monitoring, differentiation from Philadelphia-positive acute leukemia, subtype-specific selection of induction therapy, and combination with tyrosine kinase inhibitors. Given that allogeneic hematopoietic stem cell transplantation currently remains the primary curative intervention for CML-BP, we also provide recommendations for the timing of transplantation, donor and graft selection, selection of a conditioning regimen and prophylaxis for graft-versus-host disease, post-transplant TKI therapy, and management of molecular relapse. Management according to the treatment recommendations presented here is intended to provide the basis for the design of future prospective clinical trials to improve outcomes for this challenging disease.

Using immunotherapy and novel trial designs to optimise front-line therapy in adult acute lymphoblastic leukaemia: breaking with the traditions of the past

Multidrug chemotherapy has historically been the cornerstone of therapy for both children and adults with acute lymphocytic leukaemia. However, in the past decade, several novel immunotherapies have proven to be highly effective in the treatment of acute lymphocytic leukaemia, including the anti-CD22 antibody-drug conjugate inotuzumab ozogamicin, the CD3 × CD19 bispecific antibody blinatumomab, and two CD19-directed chimeric antigen receptor T-cell products. These agents are all approved in the USA as monotherapy for relapsed or refractory B-cell acute lymphocytic leukaemia. However, their use as single agents in the salvage setting might not be taking full advantage of their anti-leukaemia potential, because our ability to cure a patient is likely to be greatest when the most effective therapies are safety integrated into front-line treatment regimens. Several ongoing studies have yielded encouraging data with routine incorporation of inotuzumab ozogamicin or blinatumomab, or both, in patients with newly diagnosed acute lymphocytic leukaemia, and these approaches are emerging as new standards of care. In Philadelphia chromosome-positive acute lymphocytic leukaemia, chemotherapy-free regimens combining blinatumomab and a BCR-ABL1 tyrosine kinase inhibitor are changing acute lymphocytic leukaemia therapy, highlighting the potential for these novel agents to reduce-or perhaps eliminate-the need for chemotherapy in some subtypes. In this Viewpoint, we review promising data from ongoing clinical trials of novel immunotherapy-based combinations that are being explored in patients with newly diagnosed acute lymphocytic leukaemia. We also discuss the challenges of randomised studies in the rapidly evolving therapeutic landscape and argue for the ability of well designed, non-randomised studies to more rapidly advance the standard of care in acute lymphocytic leukaemia.

Treatment de-escalation in Philadelphia chromosome-positive B-cell acute lymphoblastic leukemia: the emerging role of chemotherapy-free regimens

The management of Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) has witnessed major progress over the past two decades. Initially, the incorporation of the first-generation BCR::ABL1 tyrosine kinase inhibitor (TKI) imatinib into intensive chemotherapy regimens improved outcomes compared with chemotherapy alone. The combinations of chemotherapy with second- or third-generation TKIs further improved outcomes, with higher rates of complete molecular remission (CMR) and superior survival. The combination of ponatinib plus chemotherapy resulted in durable remissions and prolonged long-term survival, even in patients who did not receive allogeneic stem cell transplantation (SCT). The promising results seen with later-generation TKIs have caused many to re-evaluate the role of allogeneic SCT for patients who achieve CMR with potent TKI regimens. Recently, the chemotherapy-free combinations of blinatumomab plus TKIs were shown to be safe and effective in newly diagnosed Ph-positive ALL, sparing patients the toxicities associated with intensive chemotherapy. In particular, encouraging early results have been seen with the combination of blinatumomab plus ponatinib, suggesting that this regimen may represent a chemotherapy-free and SCT-sparing strategy for patients with Ph-positive ALL. Herein, we discuss the current evidence for frontline therapies of Ph-positive ALL, the treatment de-escalation strategies over time, and the role of allogeneic SCT in view of the emergence of newer chemotherapy-free regimens using potent TKIs.

Pathogenesis and management of accelerated and blast phases of chronic myeloid leukemia

The treatment of chronic myeloid leukemia (CML) with tyrosine kinase inhibitors (TKIs) has been a model for cancer therapy development. Though most patients with CML have a normal quality and duration of life with TKI therapy, some patients progress to accelerated phase (AP) and blast phase (BP), both of which have a relatively poor prognosis. The rates of progression have reduced significantly from over >20% in the pre-TKI era to <5% now, largely due to refinements in CML therapy and response monitoring. Significant insights have been gained into the mechanisms of disease transformation including the role of additional cytogenetic abnormalities, somatic mutations, and other genomic alterations present at diagnosis or evolving on therapy. This knowledge is helping to optimize TKI therapy, improve prognostication and inform the development of novel combination regimens in these patients. While patients with de novo CML-AP have outcomes almost similar to CML in chronic phase (CP), those transformed from previously treated CML-CP should receive second- or third- generation TKIs and be strongly considered for allogeneic stem cell transplantation (allo-SCT). Similarly, patients with transformed CML-BP have particularly dismal outcomes with a median survival usually less than one year. Combination regimens with a potent TKI such as ponatinib followed by allo-SCT can achieve long-term survival in some transformed BP patients. Regimens including venetoclax in myeloid BP or inotuzumab ozogamicin or blinatumomab in lymphoid BP might lead to deeper and longer responses, facilitating potentially curative allo-SCT for patients with CML-BP once CP is achieved. Newer agents and novel combination therapies are further expanding the therapeutic arsenal in advanced phase CML.

Combining blinatumomab and donor lymphocyte infusion in B-ALL patients relapsing after allogeneic hematopoietic cell transplantation: a study of the SFGM-TC

Relapsed B-cell acute lymphoblastic leukemia (B-ALL) after allogeneic stem cell transplantation (allo-HCT) still represents a major concern with poor outcomes. The aim of this study is to compare the efficacy and safety of blinatumomab and donor lymphocyte infusion (DLI) versus blinatumomab alone in this setting. This is a multicenter retrospective study from centers of SFGM-TC. All transplanted patients who received blinatumomab salvage therapy were included. Patients who received DLI from 1 month before to 100 days after the starting of blinatumomab were included in the blina-DLI group. Seventy-two patients were included. Medium follow-up was 38 months. Fifty received blinatumomab alone and 22 the association blinatumomab-DLI. Two-year overall survival (OS) was 31% in the blinatumomab group and 43% in the blinatumomab-DLI group (p = 0.31). Studying DLI as a time dependent variable, PFS did not significantly differ between the 2 groups (HR:0.7, 95% CI: 0.4-1.5). In multivariate analysis, DLI was not a prognostic factor for OS, progression-free survival and progression/relapse incidence. Adverse events and graft-versus-disease rates were comparable in the 2 groups. In conclusion, adding DLI between 1 month before and 100 days after start of blinatumomab is safe and does not seem to improve outcomes in B-ALL patients who relapsed after allo-HCT.

Treatment of blast phase chronic myeloid leukaemia: A rare and challenging entity

Despite the success of BCR-ABL-specific tyrosine kinase inhibitors (TKIs) such as imatinib in chronic phase (CP) chronic myeloid leukaemia (CML), patients with blast phase (BP)-CML continue to have a dismal outcome with median survival of less than one year from diagnosis. Thus BP-CML remains a critical unmet clinical need in the management of CML. Our understanding of the biology of BP-CML continues to grow; genomic instability leads to acquisition of mutations which drive leukaemic progenitor cells to develop self-renewal properties, resulting in differentiation block and a poor-prognosis acute leukaemia which may be myeloid, lymphoid or bi-phenotypic. Similar advances in therapy are urgently needed to improve patient outcomes; however, this is challenging given the rarity and heterogeneity of BP-CML, leading to difficulty in designing and recruiting to prospective clinical trials. This review will explore the treatment of BP-CML, evaluating the data for TKI therapy alone, combinations with intensive chemotherapy, the role of allogeneic haemopoietic stem cell transplantation, the use of novel agents and clinical trials, as well as discussing the most appropriate methods for diagnosing BP and assessing response to therapy, and factors predicting outcome.

Modern Management Options for Ph+ ALL

Simple Summary

The use of tyrosine kinase inhibitors has represented a major step forward in the therapy of Philadelphia chromosome positive acute lymphoblastic leukemia. Recent improvements in the therapy are focused on early use of third generation tyrosine kinase inhibitors, their combination with immunotherapy, the refined indication of allogeneic hematopoietic stem cell transplantation, the optimal use and duration of maintenance therapy, and the management of patients with molecular or hematological relapse with combination of targeted therapies and immunotherapy, including cellular therapies. Improvements in the assessment of measurable residual disease and in the detection of mutations in the ABL1 domain are contributing to the better selection of the therapy for newly diagnosed as well as for relapsed or refractory patients.

Abstract

Impressive advances have been achieved in the management of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) since the initial concurrent use of imatinib and standard chemotherapy. The attenuation of chemotherapy has proven to be equally effective and less toxic, the use of third generation TKI upfront has improved the frequency of complete molecular response and the survival rate, and the combination of tyrosine kinase inhibitors with immunotherapy has further increased the rate of molecular response to 70–80% after consolidation, which has been translated into a survival rate of 75–90% in recent trials. As a result of these improvements, the role of allogeneic hematopoietic stem cell transplantation is being redefined. The methodology of measurable residual disease assessment and the detection of ABL1 mutations are also improving and will contribute to a more precise selection of the treatment for newly diagnosed and relapsed or refractory (R/R) patients. Finally, new compounds combined with immunotherapeutic approaches, including cellular therapy, are being used as rescue therapy and will hopefully be included in first line therapy in the near future. This article will review and update the modern management of patients with Ph+ ALL.

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.

Treatment of Adults With Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia-From Intensive Chemotherapy Combinations to Chemotherapy-Free Regimens: A Review

Importance

With the advent of potent BCR::ABL1 tyrosine kinase inhibitors (TKIs), Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) is now a relatively favorable-risk acute leukemia. In this review, we discuss the current evidence for frontline therapies of Ph-positive ALL, the major principles that guide therapy, and the progress with chemotherapy-free regimens.

Observations

Incorporating TKIs into the chemotherapy regimens of patients with newly diagnosed Ph-positive ALL has led to improved remission rates, higher probability of reaching allogeneic stem cell transplantation (SCT), and longer survival compared with chemotherapy alone. Early achievement of a complete molecular remission (CMR) is an important end point in Ph-positive ALL and identifies patients who have excellent long-term survival and may not need allogeneic SCT. Second-generation TKIs combined with intensive or low-intensity chemotherapy resulted in higher CMR rates compared with imatinib-based regimens. This translated into better outcomes, with less reliance on allogeneic SCT. To further improve the outcomes, the potent third-generation TKI ponatinib was added to chemotherapy. The combination of hyper-CVAD and ponatinib resulted in an overall CMR rate of 84% and a 5-year survival rate of 73% and 86% among patients who did and did not undergo allogeneic SCT, respectively, suggesting that allogeneic SCT may not be needed with this regimen. The recent chemotherapy-free combination of dasatinib and blinatumomab was safe and effective in patients with newly diagnosed Ph-positive ALL and resulted in an estimated 3-year OS rate of 80%; 50% of patients underwent allogeneic SCT. The chemotherapy-free regimen of ponatinib and blinatumomab resulted in a CMR rate of 86% and a 2-year survival rate of 93%, with no relapses or leukemia-related deaths, and with only 1 patient proceeding to allogeneic SCT.

Conclusions and Relevance

The promising results obtained with the chemotherapy-free regimens of blinatumomab plus TKIs question the role of allogeneic SCT in first remission. Patients with Ph-positive ALL who achieve early and deep molecular responses have excellent long-term outcomes and may not benefit from allogeneic SCT.

Novel strategies for the mitigation of cytokine release syndrome induced by T cell engaging therapies with a focus on the use of kinase inhibitors

T cell engaging therapies, like CAR-T cells and T cell engagers, redirect T cells toward tumor cells, facilitating the formation of a cytotoxic synapse and resulting in subsequent tumor cell killing. T cell receptor or CAR-T downstream signaling triggers a release of pro-inflammatory cytokines, which can induce a Cytokine Release Syndrome (CRS). The incidence of CRS is still hardly predictable among individuals and remains one of the major dose-limiting safety liabilities associated with on-target activity of T cell engaging therapies. This emphasizes the need to elaborate mitigation strategies, which reduce cytokine release while retaining efficacy. Here, we review pre-clinical and clinical approaches applied for the management of CRS symptoms in the context of T cell engaging therapies, highlighting the use of tyrosine kinase inhibitors as an emerging mitigation strategy. In particular, we focus on the effects of Bruton's tyrosine kinase (BTK), Src family including Lck, mammalian target of rapamycin (mTOR) and Janus tyrosine kinase (JAK) inhibitors on T cell functionality and cytokine release, to provide a rationale for their use as mitigation strategies against CRS in the context of T cell engaging therapies.

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.

Clinical Development and Therapeutic Applications of Bispecific Antibodies for Hematologic Malignancies

Bispecific antibodies are composed of two monoclonal antibodies that engage T cells with tumor cell antigens and lead to tumor cell lysis. The most common types fall into the category of bispecific T cell engagers, or BiTEs, that have the canonical CD3-CD19 bispecific construct. Blinatumomab is the first bispecific antibody that received FDA approval for relapsed refractory B cell precursor acute lymphoblastic leukemia. Blinatumomab has been shown to have robust clinical outcomes and is associated with adverse events such as cytokine release syndrome and neurotoxicity. Other bispecific antibodies are under clinical investigation for multiple myeloma and acute myeloid leukemia. Along with immune checkpoint inhibitors and chimeric antigen T cell receptor therapies, bispecific antibodies are considered a mainstay as a therapeutic option for cancer immunotherapies for Hematologic malignancies.

BCR::ABL1 tyrosine kinase inhibitors hamper the therapeutic efficacy of blinatumomab in vitro

PURPOSE

Acute B-lymphoblastic leukemia (B-ALL) is a malignant disease characterized by accumulation of clonal immature lymphocytes in the bone marrow and peripheral blood. The approval of BCR::ABL1 tyrosine kinase inhibitors (TKI) such as imatinib, dasatinib, nilotinib and ponatinib marked a milestone in targeted therapy only for a subset of patients carrying the translocation t(9;22)(q34;q11). Immunotherapy with the bispecific antibody (bsAb) blinatumomab targeting CD19xCD3 revolutionized treatment of all B-ALL cases. The combination of both TKI and bsAb, so-called "dual targeting", is currently under clinical investigation, although TKI might influence T cell effects.

METHODS

We here investigated the combination of different TKI and blinatumomab in BCR::ABL1⁺ and BCR::ABL1^- B-ALL cell lines and primary samples regarding T cell proliferation, differentiation, cytokine release and killing of tumor cells.

RESULTS

In vitro analysis revealed profound reduction of T cell proliferation, differentiation, cytokine release and killing of tumor cells upon application of BCR::ABL1 TKI with blinatumomab. Inhibition was more pronounced with dasatinib and ponatinib compared to nilotinib and imatinib. T cell signalling after CD3 stimulation was impaired by TKI mirrored by inhibition of LCK phosphorylation. This known off-target effect might influence the efficacy of bsAb therapy when combined with BCR::ABL1 TKI.

CONCLUSION

In conclusion, we propose that nilotinib and imatinib might also be suitable substances for combination with blinatumomab and suggest evaluation in clinical trials.

Treatment of Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia in Adults

Simple Summary

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

Abstract

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

Ponatinib with fludarabine, cytarabine, idarubicin, and granulocyte colony-stimulating factor chemotherapy for patients with blast-phase chronic myeloid leukaemia (MATCHPOINT): a single-arm, multicentre, phase 1/2 trial

BACKGROUND

Outcomes for patients with blast-phase chronic myeloid leukaemia are poor. Long-term survival depends on reaching a second chronic phase, followed by allogeneic haematopoietic stem-cell transplantation (HSCT). We investigated whether the novel combination of the tyrosine-kinase inhibitor ponatinib with fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin (FLAG-IDA) could improve response and optimise allogeneic HSCT outcomes in patients with blast-phase chronic myeloid leukaemia. The aim was to identify a dose of ponatinib, which combined with FLAG-IDA, showed clinically meaningful activity and tolerability.

METHODS

MATCHPOINT was a seamless, phase 1/2, multicentre trial done in eight UK Trials Acceleration Programme-funded centres. Eligible participants were adults (aged ≥16 years) with Philadelphia chromosome-positive or BCR-ABL1-positive blast-phase chronic myeloid leukaemia, suitable for intensive chemotherapy. Participants received up to two cycles of ponatinib with FLAG-IDA. Experimental doses of oral ponatinib (given from day 1 to day 28 of FLAG-IDA) were between 15 mg alternate days and 45 mg once daily and the starting dose was 30 mg once daily. Intravenous fludarabine (30 mg/m2 for 5 days), cytarabine (2 g/m2 for 5 days), and idarubicin (8 mg/m2 for 3 days), and subcutaneous granulocyte colony-stimulating factor (if used), were delivered according to local protocols. We used an innovative EffTox design to investigate the activity and tolerability of ponatinib-FLAG-IDA; the primary endpoints were the optimal ponatinib dose meeting prespecified thresholds of activity (inducement of second chronic phase defined as either haematological or minor cytogenetic response) and tolerability (dose-limiting toxicties). Analyses were planned on an intention-to-treat basis. MATCHPOINT was registered as an International Standard Randomised Controlled Trial, ISRCTN98986889, and has completed recruitment; the final results are presented.

FINDINGS

Between March 19, 2015, and April 26, 2018, 17 patients (12 men, five women) were recruited, 16 of whom were evaluable for the coprimary outcomes. Median follow-up was 41 months (IQR 36-48). The EffTox model simultaneously considered clinical responses and dose-limiting toxicities, and determined the optimal ponatinib dose as 30 mg daily, combined with FLAG-IDA. 11 (69%) of 16 patients were in the second chronic phase after one cycle of treatment. Four (25%) patients had a dose-limiting toxicity (comprising cardiomyopathy and grade 4 increased alanine aminotransferase, cerebral venous sinus thrombosis, grade 3 increased amylase, and grade 4 increased alanine aminotransferase), fulfilling the criteria for clinically relevant activity and toxicity. 12 (71%) of 17 patients proceeded to allogeneic HSCT. The most common grade 3-4 non-haematological adverse events were lung infection (n=4 [24%]), fever (n=3 [18%]), and hypocalcaemia (n=3 [18%]). There were 12 serious adverse events in 11 (65%) patients. Three (18%) patients died due to treatment-related events (due to cardiomyopathy, pulmonary haemorrhage, and bone marrow aplasia).

INTERPRETATION

Ponatinib-FLAG-IDA can induce second chronic phase in patients with blast-phase chronic myeloid leukaemia, representing an active salvage therapy to bridge to allogeneic HSCT. The number of treatment-related deaths is not in excess of what would be expected in this very high-risk group of patients receiving intensive chemotherapy. The efficient EffTox method is a model for investigating novel therapies in ultra-orphan cancers.

FUNDING

Blood Cancer UK and Incyte.

The cure of leukemia through the optimist's prism

Progress is occurring at a dizzying rate across all leukemias. Since the authors' review of the topic in Cancer in 2018, numerous discoveries have been made that have improved the therapy and outcomes of several leukemia subsets. Hairy cell leukemia is potentially curable with a single course of cladribine followed by rituximab (10-year survival, ≥90%). Acute promyelocytic leukemia is curable at a rate of 80% to 90% with a nonchemotherapy regimen of all-trans retinoic acid and arsenic trioxide. The cure rate for core-binding factor acute myeloid leukemia (AML) is ≥75% with fludarabine, high-dose cytarabine, and gemtuzumab ozogamicin. Survival for patients with chronic myeloid leukemia is close to that for an age-matched normal population with BCR-ABL1 tyrosine kinase inhibitors (TKIs). Chronic lymphocytic leukemia, a previously incurable disease, may now be potentially curable with a finite duration of therapy with Bruton tyrosine kinase inhibitors and venetoclax. The estimated 5-year survival rate for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) exceeds 70% with intensive chemotherapy and ponatinib, a third-generation BCR-ABL1 TKI, and more recent nonchemotherapy regimens using dasatinib or ponatinib with blinatumomab are producing outstanding results. Survival in both younger and older patients with ALL has improved with the addition of antibodies targeting CD20, CD19 (blinatumomab), and CD22 (inotuzumab) to chemotherapy. Several recent drug discoveries (venetoclax, FLT3 and IDH inhibitors, and oral hypomethylating agents) are also improving outcomes for younger and older patients with AML and for those with higher risk myelodysplastic syndrome.

Has Ph-like ALL Superseded Ph+ ALL as the Least Favorable Subtype?

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a subset of high-risk B-ALL associated with high relapse risk and inferior clinical outcomes across the pediatric-to-adult age spectrum. Ph-like ALL is characterized by frequent IKZF1 alterations and a kinase-activated gene expression profile similar to that of Philadelphia chromosome-positive (Ph+) ALL, yet lacks the canonical BCR-ABL1 rearrangement. Advances in high-throughput sequencing technologies during the past decade have unraveled the genomic landscape of Ph-like ALL, revealing a diverse array of kinase-activating translocations and mutations that may be amenable to targeted therapies that have set a remarkable precision medicine paradigm for patients with Ph + ALL. Collaborative scientific efforts to identify and characterise Ph-like ALL during the past decade has directly informed current precision medicine trials investigating the therapeutic potential of tyrosine kinase inhibitor-based therapies for children, adolescents, and adults with Ph-like ALL, although the most optimal treatment paradigm for this high-risk group of patients has yet to be established. Herein, we describe the epidemiology, clinical features, and biology of Ph-like ALL, highlight challenges in implementing pragmatic and cost-effective diagnostic algorithms in the clinic, and describe the milieu of treatment strategies under active investigation that strive to decrease relapse risk and improve long-term survival for patients with Ph-like ALL as has been successfully achieved for those with Ph + ALL.

Optimizing the treatment of acute lymphoblastic leukemia in younger and older adults: new drugs and evolving paradigms

In the past decade, the available treatments for patients with acute lymphoblastic leukemia (ALL) have rapidly expanded, in parallel with an increased understanding of the genomic features that impact the disease biology and clinical outcomes. With the development of the anti-CD22 antibody-drug conjugate inotuzumab ozogamicin, the CD3-CD19 bispecific T-cell engager antibody blinatumomab, CD19 chimeric antigen receptor T-cell therapy, and the potent BCR-ABL1 tyrosine kinase inhibitor ponatinib, the outlook of ALL in both younger and older adults has substantially improved. The availability of highly effective drugs raised important questions concerning the optimal combination and sequence of these agents, their incorporation into frontline regimens, and the role of hematopoietic stem cell transplantation. In this review, we discuss the rapidly evolving paradigms in the treatment of ALL, highlighting both established and effective regimens, as well as promising new therapies that are being evaluated in ongoing clinical trials. We specifically focus on novel combination regimens in both the frontline and salvage settings that are leading to new standards of care in the treatment of ALL.

INCB84344-201: Ponatinib and steroids in frontline therapy of unfit patients with Ph+ acute lymphoblastic leukemia

In patients with newly diagnosed Ph⁺ ALL, ponatinib and prednisone therapy resulted in long molecular remissions and few resistance mutations.

The observed high rates of discontinuation and dose modification suggest that a lower dose may be more appropriate in older/unfit patients.

Tyrosine kinase inhibitors have improved survival for patients with Philadelphia chromosome–positive (Ph⁺) acute lymphoblastic leukemia (ALL). However, prognosis for old or unfit patients remains poor. In the INCB84344-201 (formerly GIMEMA LAL 1811) prospective, multicenter, phase 2 trial, we tested the efficacy and safety of ponatinib plus prednisone in newly diagnosed patients with Ph⁺ ALL ≥60 years, or unfit for intensive chemotherapy and stem cell transplantation. Forty-four patients received oral ponatinib 45 mg/d for 48 weeks (core phase), with prednisone tapered to 60 mg/m²/d from days-14-29. Prophylactic intrathecal chemotherapy was administered monthly. Median age was 66.5 years (range, 26-85). The primary endpoint (complete hematologic response [CHR] at 24 weeks) was reached in 38/44 patients (86.4%); complete molecular response (CMR) in 18/44 patients (40.9%) at 24 weeks. 61.4% of patients completed the core phase. As of 24 April 2020, median event-free survival was 14.31 months (95% CI 9.30-22.31). Median overall survival and duration of CHR were not reached; median duration of CMR was 11.6 months. Most common treatment-emergent adverse events (TEAEs) were rash (36.4%), asthenia (22.7%), alanine transaminase increase (15.9%), erythema (15.9%), and γ-glutamyltransferase increase (15.9%). Cardiac and vascular TEAEs occurred in 29.5% (grade ≥3, 18.2%) and 27.3% (grade ≥3, 15.9%), respectively. Dose reductions, interruptions, and discontinuations due to TEAEs occurred in 43.2%, 43.2%, and 27.3% of patients, respectively; 5 patients had fatal TEAEs. Ponatinib and prednisone showed efficacy in unfit patients with Ph⁺ ALL; however, a lower ponatinib dose may be more appropriate in this population. This trial was registered at www.clinicaltrials.gov as #NCT01641107.

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

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

SOHO State of the Art Updates & Next Questions: Intensive and Non-Intensive Approaches for Adults With Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) was historically considered to be a very poor-risk subtype of ALL. However, with the introduction of highly potent BCR-ABL tyrosine kinase inhibitors (TKIs), Ph+ ALL can now be considered relatively favorable-risk acute leukemia. Considering the high rates of measurable residual disease negativity and excellent long-term survival that has been achieved with regimens incorporating later-generation TKIs and particularly with ponatinib, lower-intensity and even chemotherapy-free regimens are now being evaluated for patients of all ages with Ph+ ALL. The very encouraging early results observed with blinatumomab-based, chemotherapy-free regimens challenge previous notions that all patients with Ph+ ALL should undergo allogeneic stem cell transplantation in first remission, as these regimens are capable of achieving deep and durable remissions without need for transplant in the vast majority of patients, particularly when combined with ponatinib. In this review, we discuss the evolving approach to the treatment of adults with newly diagnosed Ph+ ALL and the major principles that should guide therapy in this disease. We also review the rationale and data supporting the use of novel, chemotherapy-free regimens in Ph+ ALL, and how these approaches may soon become new standards of care.

Inotuzumab ozogamicin with bosutinib for relapsed or refractory Philadelphia chromosome positive acute lymphoblastic leukemia or lymphoid blast phase of chronic myeloid leukemia

Relapsed/refractory (R/R) Philadelphia chromosome positive acute lymphoblastic leukemia (Ph + ALL) and lymphoid blast phase of chronic myeloid leukemia (LBP-CML) have poor outcomes. We designed a phase 1/2 study combining inotuzumab ozogamicin with bosutinib for this patient population. Patients with T315I mutation were excluded. Bosutinib was administered daily at three dose levels (300 mg/d, 400 mg/d, 500 mg/d) in a 3 + 3 design. Inotuzumab ozogamicin was dosed weekly during cycle one, and once every 4 weeks subsequently for a total of six cycles. The primary objective was to determine the safety and the maximum tolerated dose (MTD) of bosutinib in combination with inotuzumab ozogamicin. Eighteen patients were enrolled (Ph-positive ALL, n = 16; LBP-CML, n = 2). The median age was 62 years (range, 19-74) and the median number of prior therapies was one (range, 1-5). Dose limiting toxicities included grade 3 skin rash and bosutinib 400 mg daily was determined as the MTD. The most frequent grade 3/4 treatment-emergent adverse events were thrombocytopenia (60%) and neutropenia (38%). A complete response (CR) / CR with incomplete count recovery (CRi) was achieved in 15/18 (83%) patients; 11/18 (61%) patients achieved negative measurable residual disease by flow cytometry. Complete molecular response was noted in 10/18 (56%) patients. The 30-day mortality was 0%. After a median follow-up of 44 months, the median duration of response and overall survival were 7.7 months and 13.5 months, respectively. Six patients had a subsequent allogeneic stem cell transplant. No patient developed veno-occlusive disease. Inotuzumab ozogamicin with bosutinib was well tolerated in R/R Ph-positive ALL and LBP-CML.

Src/lck inhibitor dasatinib reversibly switches off cytokine release and T cell cytotoxicity following stimulation with T cell bispecific antibodies

Background

T cell engagers are bispecific antibodies recognizing, with one moiety, the CD3ε chain of the T cell receptor and, with the other moiety, specific tumor surface antigens. Crosslinking of CD3 upon simultaneous binding to tumor antigens triggers T cell activation, proliferation and cytokine release, leading to tumor cell killing. Treatment with T cell engagers can be associated with safety liabilities due to on-target on-tumor, on-target off-tumor cytotoxic activity and cytokine release syndrome (CRS). Tyrosine kinases such as SRC, LCK or ZAP70 are involved in downstream signaling pathways after engagement of the T cell receptor and blocking these kinases might serve to abrogate T cell activation when required (online supplemental material 1). Dasatinib was previously identified as a potent kinase inhibitor that switches off CAR T cell functionality.

Methods

Using an in vitro model of target cell killing by human peripheral blood mononuclear cells, we assessed the effects of dasatinib combined with 2+1 T cell bispecific antibodies (TCBs) including CEA-TCB, CD19-TCB or HLA-A2 WT1-TCB on T cell activation, proliferation and target cell killing measured by flow cytometry and cytokine release measured by Luminex. To determine the effective dose of dasatinib, the Incucyte system was used to monitor the kinetics of TCB-mediated target cell killing in the presence of escalating concentrations of dasatinib. Last, the effects of dasatinib were evaluated in vivo in humanized NSG mice co-treated with CD19-TCB. The count of CD20⁺ blood B cells was used as a readout of efficacy of TCB-mediated killing and cytokine levels were measured in the serum.

Results

Dasatinib concentrations above 50 nM prevented cytokine release and switched off-target cell killing, which were subsequently restored on removal of dasatinib. In addition, dasatinib prevented CD19-TCB-mediated B cell depletion in humanized NSG mice. These data confirm that dasatinib can act as a rapid and reversible on/off switch for activated T cells at pharmacologically relevant doses as they are applied in patients according to the label.

Conclusion

Taken together, we provide evidence for the use of dasatinib as a pharmacological on/off switch to mitigate off-tumor toxicities or CRS by T cell bispecific antibodies.

Concomitant use of a dual Src/ABL kinase inhibitor eliminates the in vitro efficacy of blinatumomab against Ph+ ALL

Blinatumomab is currently approved for use as a single agent in relapsed and refractory acute lymphoblastic leukemia (ALL). Cytotoxicity is mediated via signaling through the T-cell receptor (TCR). There is now much interest in combining blinatumomab with targeted therapies, particularly in Philadelphia chromosome-positive ALL (Ph+ ALL). However, some second- and third-generation ABL inhibitors also potently inhibit Src family kinases that are important in TCR signaling. We combined ABL inhibitors and dual Src/ABL inhibitors with blinatumomab in vitro from both healthy donor samples and primary samples from patients with Ph+ ALL. Blinatumomab alone led to both T-cell proliferation and elimination of target CD19+ cells and enhanced production of interferon-γ (IFN-γ). The addition of the ABL inhibitors imatinib or nilotinib to blinatumomab did not inhibit T-cell proliferation or IFN-γ production. However, the addition of dasatinib or ponatinib inhibited T-cell proliferation and IFN-γ production. Importantly, there was no loss of CD19+ cells treated with blinatumomab plus dasatinib or ponatinib in healthy samples or samples with a resistant ABL T315I mutation by dasatinib in combination with blinatumomab. These in vitro findings bring pause to the excitement of combination therapies, highlighting the importance of maintaining T-cell function with targeted therapies.

Efficacy of Inotuzumab Ozogamicin plus Ponatinib Followed by Allogeneic Stem Cell Transplantation in a Patient with Relapsed Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) is an aggressive disease with poor outcomes. Despite the incorporation of tyrosine kinase inhibitors (TKIs) in the therapeutic strategies, patients who relapse after chemotherapy plus TKI have poor overall survival (OS) and less chance to proceed to hematopoietic stem cell transplantation (HSCT) which remains the only curative approach. Therefore, new drugs, such as antibody-targeted therapies alone or in combination with TKIs, offer new therapeutic options for those patients. However, the combination of inotuzumab plus ponatinib has limited application. We present a case of a patient affected by Ph + ALL with T315I mutation successfully treated after early relapse with inotuzumab plus ponatinib, followed by allogeneic HSCT and ponatinib maintenance.

The landscape of bispecific T cell engager in cancer treatment

T cell-based immunotherapies have revolutionized treatment paradigms in various cancers, however, limited response rates secondary to lack of significant T-cell infiltration in the tumor site remain a major problem. To address this limitation, strategies for redirecting T cells to treat cancer are being intensively investigated, while the bispecific T cell engager (BiTE) therapy constitutes one of the most promising therapeutic approaches. BiTE is a bispecific antibody construct with a unique function, simultaneously binding an antigen on tumor cells and a surface molecule on T cells to induce tumor lysis. BiTE therapy represented by blinatumomab has achieved impressive efficacy in the treatment of B cell malignancies. However, major mechanisms of resistance to BiTE therapy are associated with antigen loss and immunosuppressive factors such as the upregulation of immune checkpoints. Thus, modification of antibody constructs and searching for combination strategies designed to further enhance treatment efficacy as well as reduce toxicity has become an urgent issue, especially for solid tumors in which response to BiTE therapy is always poor. In particular, immunotherapies focusing on innate immunity have attracted increasing interest and have shown promising anti-tumor activity by engaging innate cells or innate-like cells, which can be used alone or complement current therapies. In this review, we depict the landscape of BiTE therapy, including clinical advances with potential response predictors, challenges of treatment toxicity and resistance, and developments of novel immune cell-based engager therapy.

A tyrosine kinase inhibitor-induced interferon response positively associates with clinical response in EGFR-mutant lung cancer

Tyrosine kinase inhibitors (TKIs) targeting EGFR-mutant lung cancers promote a range of tumor regression responses to yield variable residual disease, a likely incubator for acquired resistance. Herein, rapid transcriptional responses induced by TKIs early in treatment that associate with the range of patient responses were explored. RNAseq was performed on EGFR mutant cell lines treated in vitro with osimertinib and on tumor biopsies of eight EGFR mutant lung cancer patients before and after 2 weeks of TKI treatment. Data were evaluated for gene expression programs altered upon TKI treatment. Chemokine and cytokine expression were measured by ELISA and quantitative RT-PCR. IκB Kinase (IKK) and JAK-STAT pathway dependence was tested with pharmacologic and molecular inhibitors. Tumor sections were stained for the T-cell marker CD3. Osimertinib stimulated dynamic, yet wide-ranging interferon (IFN) program regulation in EGFR mutant cell lines. IL6 and CXCL10 induction varied markedly among the EGFR mutant cell lines and was sensitive to IKK and JAK-STAT inhibitors. Analysis of matched patient biopsy pairs revealed marked, yet varied enrichment of IFN transcriptional programs, effector immune cell signatures and T-cell content in treated tumors that positively correlated with time to progression in the patients. EGFR-specific TKIs induce wide-ranging IFN response program activation originating within the cancer cell. The strong association of IFN program induction and duration of clinical response indicates that the TKI-induced IFN program instructs variable recruitment and participation of immune cells in the overall therapeutic response.

Allogeneic transplantation for Ph+ acute lymphoblastic leukemia with posttransplantation cyclophosphamide

Allogeneic blood or marrow transplantation (alloBMT) is standard of care for adults with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) in first complete remission (CR1). The routine pretransplant and posttransplant use of tyrosine kinase inhibitors (TKIs) has dramatically improved outcomes, but the optimal conditioning regimen, donor type, and TKI remain undefined. The bone marrow transplant database at Johns Hopkins was queried for adult patients with de novo Ph+ ALL who received alloBMT using posttransplantation cyclophosphamide (PTCy) as a component of graft-versus-host disease (GVHD) prophylaxis from 2008 to 2018. Among transplants for Ph+ ALL, 69 (85%) were performed in CR1, and 12 (15%) were performed in second or greater remission (CR2+). The majority of transplants (58%) were HLA haploidentical. Nearly all patients (91.4%) initiated TKI posttransplant. For patients in CR1, the 5-year relapse-free survival (RFS) was 66%. The use of nonmyeloablative conditioning, absence of measurable residual disease (MRD) according to flow cytometry at transplant, and the use of dasatinib vs imatinib at diagnosis were associated with improved overall survival (OS) and RFS. Neither donor type nor recipient age ≥60 years affected RFS. When analyzing all transplants, alloBMT in CR1 (vs CR2+) and the absence of pretransplant MRD were associated with improved RFS. Most relapses were associated with the emergence of kinase domain mutations. The cumulative incidence of grade 3 to 4 acute GVHD at 1 year was 9%, and moderate to severe chronic GVHD at 2 years was 8%. Nonmyeloablative alloBMT with PTCy for Ph+ ALL in an MRD-negative CR1 after initial treatment with dasatinib yields favorable outcomes.

Outcome of patients with chronic myeloid leukemia in lymphoid blastic phase and Philadelphia chromosome-positive acute lymphoblastic leukemia treated with hyper-CVAD and dasatinib

BACKGROUND

Dasatinib monotherapy has demonstrated modest clinical activity in chronic myeloid leukemia in lymphoid blastic phase (CML-LBP). The outcome of Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) has dramatically improved with hyperfractionated cyclophosphamide, vincristine sulfate, doxorubicin hydrochloride, and dexamethasone (hyper-CVAD) in combination with tyrosine kinase inhibitors (TKIs).

METHODS

The authors reviewed 85 patients (23 with CML-LBP and 62 with newly diagnosed Ph-positive ALL) who received hyper-CVAD plus dasatinib.

RESULTS

In the CML-LBP cohort, 19 had prior chronic myeloid leukemia as chronic phase (n = 17; 74%), accelerated phase (n = 1; 4%), or myeloid blastic phase (n = 1; 4%); 4 (17%) presented with de novo CML-LBP. The BCR-ABL1 transcript was p210 in 22 patients (96%) and p190 in 1 patient (4%). In the Ph-positive ALL cohort, p210 and p190 transcripts were detected in 13 patients (21%) and 48 patients (77%), respectively. Patients with CML-LBP were less likely to achieve deep molecular remission than patients with Ph-positive ALL: the major molecular response (MMR) rates were 70% and 95%, respectively (P = .007), and the complete molecular response (CMR) rates were 55% and 74%, respectively (P = .16). Survival outcomes were similar for CML-LBP and Ph-positive ALL: the 5-year overall survival (OS) rates were 59% and 48%, respectively (P = .97). Allogeneic stem cell transplantation was associated with a better outcome in CML-LBP (5-year OS rate, 88% vs 57%; P = .04). In Ph-positive ALL, the outcome was driven by deeper molecular remission: the 5-year OS rates were 63% and 25% with CMR and MMR, respectively (P = .002).

CONCLUSIONS

The outcome of CML-LBP has improved with hyper-CVAD plus dasatinib therapy with survival comparable to that of Ph-positive ALL. Further improvement may be achieved with the use of novel TKIs and targeted agents.

Molecular remission after combination therapy with blinatumomab and ponatinib with relapsed/refractory Philadelphia chromosome-positive acute lymphocytic leukemia: two case reports

Background

The outcomes of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) can improve with allogeneic hematopoietic stem cell transplantation (HSCT) during the first complete remission after treatment with a tyrosine kinase inhibitor (TKI) combined with chemotherapy. However, frail patients who are not eligible for allogeneic HSCT or those with TKI-resistant mutations within the BCR–ABL kinase domain have a poor clinical course. Blinatumomab (BLIN) is a bispecific T-cell engager antibody construct that directs cytotoxic T cells to CD19-expressing B-ALL cells. To date, only a few studies have shown the safety and efficacy of Blinatumomab (BLIN) + TKI combination therapy for relapsed/refractory (R/R) Ph+ ALL. Here we report the case of two patients with R/R Ph+ ALL who were treated with BLIN + TKI with durable molecular response.

Case presentation

Patient 1: A 69-year-old Japanese male with R/R Ph+ ALL was treated with conventional chemotherapy and dasatinib in April 2016. In May 2018, he developed molecular relapse due to the acquisition of T315I during dasatinib maintenance therapy. Thereafter, he achieved molecular complete remission (mCR) after switching from dasatinib to ponatinib. However, he developed a second relapse after the emergence of triple compound mutations (G250E/D276G/T315I) in November 2018. He subsequently received a total of nine cycles of BLIN and ponatinib combination therapy, which resulted in sustained mCR without any adverse events. Patient 2: A 69-year-old Japanese female with R/R Ph+ ALL was treated with chemotherapy and imatinib in April 2008. She developed molecular relapse due to the emergence of the T315I mutation in October 2017. She achieved mCR after switching from imatinib to ponatinib. However, she developed a second relapse after acquiring ABL exon4 skipping in addition to T315I. She subsequently received a total of seven cycles of BLIN and ponatinib combination therapy, which resulted in sustained mCR.

Conclusion

In our two cases, BLIN + ponatinib combination therapy was highly effective for R/R Ph+ ALL without any incidence of severe adverse events. Further studies with larger cohorts are warranted to validate the safety and efficacy of this potent combination therapy.