Outcome of patients treated for relapsed or refractory acute lymphoblastic leukemia: a Therapeutic Advances in Childhood Leukemia Consortium study

Palbociclib in combination with chemotherapy in pediatric and young adult patients with relapsed/refractory acute lymphoblastic leukemia and lymphoma: A Children's Oncology Group study (AINV18P1)

BACKGROUND

Cyclin D has been shown to play an essential role in acute lymphoblastic leukemia (ALL) initiation and progression, providing rationale for targeting the CDK4/6-cyclin D complex that regulates cell cycle progression.

PROCEDURE

The Children's Oncology Group AINV18P1 phase 1 trial evaluated the CDK4/6 inhibitor, palbociclib, in combination with standard four-drug re-induction chemotherapy in children and young adults with relapsed/refractory B- and T-cell lymphoblastic leukemia (ALL) and lymphoma. Palbociclib (50 mg/m2 /dose) was administered orally once daily for 21 consecutive days, first as a single agent (Days 1-3) and subsequently combined with re-induction chemotherapy. This two-part study was designed to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D), followed by an expansion pharmacokinetic cohort.

RESULTS

Twelve heavily pretreated patients enrolled, all of whom were evaluable for toxicity. One dose-limiting hematologic toxicity (DLT) occurred at the starting dose of 50 mg/m2 /dose orally for 21 days. No additional DLTs were observed in the dose determination or pharmacokinetic expansion cohorts, and overall rates of grade 3/4 nonhematologic toxicities were comparable to those observed with the chemotherapy platform alone. Five complete responses were observed, two among four patients with T-ALL and three among seven patients with B-ALL. Pharmacokinetic studies showed similar profiles with both liquid and capsule formulations of palbociclib.

CONCLUSIONS

Palbociclib in combination with re-induction chemotherapy was well tolerated with a RP2D of 50 mg/m2 /day for 21 days. Complete responses were observed among heavily pretreated patients.

Lower Respiratory Infections in Children With Febrile Neutropenic Leukemia: A Case in a Jordanian Hospital

The study aimed to examine the prevalence of pneumonia in pediatric children diagnosed with leukemia at King Hussein Medical Center, Royal Medical Services, Amman, Jordan. The study was conducted from January 2019 to March 2020. A total of 100 hospitalized leukemia patients with febrile neutropenic episodes were evaluated for the presence of pneumonia. Samples were collected from all patients and tested for microbial growth. Univariate analysis revealed that age (P = .033) and packed cell volume (P = .006) were statistically significant risk factors, associated with the prevalence of pneumonia in leukemia patients with febrile neutropenia episodes. Similarly, as the absolute neutrophil count counts increased with an odds ratio and a 95% confidence interval of 2.386 (0.859-6.625), the odds of pneumonia in febrile neutropenic patients were more prevalent. The study reported the prevalence of pneumonia in immunocompromised febrile neutropenic patients with leukemia, which could lead to the development of evidence-based febrile neutropenic treatment protocol development. It will assure more responsive patient management and treatment.

CAR T-Cells for the Treatment of B-Cell Acute Lymphoblastic Leukemia

B-cell acute lymphoblastic leukemia (B-ALL) is the most common subtype of acute leukemia in the pediatric population. The prognosis and treatment of B-ALL have dramatically improved over the past decade with the adoption of intensive and prolonged combination chemotherapy regimens. The advent of novel immunologic agents such as blinatumomab and inotuzumab has changed the treatment landscape of B-ALL. However, patients have continued to relapse, raising the need for novel therapies. Chimeric antigen receptor (CAR) T-cells have achieved a milestone in the treatment of B-ALL. Two CD19-targeting CAR T-cells were approved by the Food and Drug Administration and the European Medicines Agency for the treatment of relapsed and/or refractory B-ALL. In this review, we review the available data regarding CD19-targeting CAR T-cells with their safety profile as well as the mechanism of resistance to these agents and the way to overcome this resistance.

The relapsed acute lymphoblastic leukemia network (ReALLNet): a multidisciplinary project from the spanish society of pediatric hematology and oncology (SEHOP)

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, with survival rates exceeding 85%. However, 15% of patients will relapse; consequently, their survival rates decrease to below 50%. Therefore, several research and innovation studies are focusing on pediatric relapsed or refractory ALL (R/R ALL). Driven by this context and following the European strategic plan to implement precision medicine equitably, the Relapsed ALL Network (ReALLNet) was launched under the umbrella of SEHOP in 2021, aiming to connect bedside patient care with expert groups in R/R ALL in an interdisciplinary and multicentric network. To achieve this objective, a board consisting of experts in diagnosis, management, preclinical research, and clinical trials has been established. The requirements of treatment centers have been evaluated, and the available oncogenomic and functional study resources have been assessed and organized. A shipping platform has been developed to process samples requiring study derivation, and an integrated diagnostic committee has been established to report results. These biological data, as well as patient outcomes, are collected in a national registry. Additionally, samples from all patients are stored in a biobank. This comprehensive repository of data and samples is expected to foster an environment where preclinical researchers and data scientists can seek to meet the complex needs of this challenging population. This proof of concept aims to demonstrate that a network-based organization, such as that embodied by ReALLNet, provides the ideal niche for the equitable and efficient implementation of "what's next" in the management of children with R/R ALL.

Children's Oncology Group AALL1331: Phase III Trial of Blinatumomab in Children, Adolescents, and Young Adults With Low-Risk B-Cell ALL in First Relapse

PURPOSE

Blinatumomab, a bispecific T-cell engager immunotherapy, is efficacious in relapsed/refractory B-cell ALL (B-ALL) and has a favorable toxicity profile. One aim of the Children's Oncology Group AALL1331 study was to compare survival of patients with low-risk (LR) first relapse of B-ALL treated with chemotherapy alone or chemotherapy plus blinatumomab.

PATIENTS AND METHODS

After block 1 reinduction, patients age 1-30 years with LR first relapse of B-ALL were randomly assigned to block 2/block 3/two continuation chemotherapy cycles/maintenance (arm C) or block 2/two cycles of continuation chemotherapy intercalated with three blinatumomab blocks/maintenance (arm D). Patients with CNS leukemia received 18 Gy cranial radiation during maintenance and intensified intrathecal chemotherapy. The primary and secondary end points were disease-free survival (DFS) and overall survival (OS).

RESULTS

The 4-year DFS/OS for the 255 LR patients accrued between December 2014 and September 2019 were 61.2% ± 5.0%/90.4% ± 3.0% for blinatumomab versus 49.5% ± 5.2%/79.6% ± 4.3% for chemotherapy (P = .089/P = .11). For bone marrow (BM) ± extramedullary (EM) (BM ± EM; n = 174) relapses, 4-year DFS/OS were 72.7% ± 5.8%/97.1% ± 2.1% for blinatumomab versus 53.7% ± 6.7%/84.8% ± 4.8% for chemotherapy (P = .015/P = .020). For isolated EM (IEM; n = 81) relapses, 4-year DFS/OS were 36.6% ± 8.2%/76.5% ± 7.5% for blinatumomab versus 38.8% ± 8.0%/68.8% ± 8.6% for chemotherapy (P = .62/P = .53). Blinatumomab was well tolerated and patients had low adverse event rates.

CONCLUSION

For children, adolescents, and young adults with B-ALL in LR first relapse, there was no statistically significant difference in DFS or OS between the blinatumomab and standard chemotherapy arms overall. However, blinatumomab significantly improved DFS and OS for the two thirds of patients with BM ± EM relapse, establishing a new standard of care for this population. By contrast, similar outcomes and poor DFS for both arms were observed in the one third of patients with IEM; new treatment approaches are needed for these patients (ClinicalTrials.gov identifier: NCT02101853).

Rational Design of Highly Potent and Selective Covalent MAP2K7 Inhibitors

The mitogen-activated protein kinase signaling cascade is conserved across eukaryotes, where it plays a critical role in the regulation of activities including proliferation, differentiation, and stress responses. This pathway propagates external stimuli through a series of phosphorylation events, which allows external signals to influence metabolic and transcriptional activities. Within the cascade, MEK, or MAP2K, enzymes occupy a molecular crossroads immediately upstream to significant signal divergence and cross-talk. One such kinase, MAP2K7, also known as MEK7 and MKK7, is a protein of great interest in the molecular pathophysiology underlying pediatric T cell acute lymphoblastic leukemia (T-ALL). Herein, we describe the rational design, synthesis, evaluation, and optimization of a novel class of irreversible MAP2K7 inhibitors. With a streamlined one-pot synthesis, favorable in vitro potency and selectivity, and promising cellular activity, this novel class of compounds wields promise as a powerful tool in the study of pediatric T-ALL.

Phase 2 study of combination chemotherapy with bortezomib in children with relapsed and refractory acute lymphoblastic leukemia

Treatment outcomes for children with relapsed and refractory acute lymphoblastic leukemia (R/R-ALL) remain poor, and the optimal induction therapy has not been determined. Bortezomib is a proteasome inhibitor that acts synergistically and additively with standard chemotherapy for ALL. We evaluated the efficacy and safety of combination chemotherapy with bortezomib in children with R/R-ALL. This single-arm, multicenter, phase 2 study was conducted in Japan between 2016 and 2020. Eligible patients were divided into two cohorts: a high-risk first-relapse cohort of untreated patients with high-risk first-relapsed ALL and an expansion cohort of patients with refractory ALL, including multiple relapses, relapse after allogeneic hematopoietic cell transplantation, and induction failure. All patients received a single course of chemotherapy as induction therapy. Sixteen patients (10 in the high-risk first-relapse cohort, six in the expansion cohort) were evaluable. The overall remission rate after induction therapy was 60% in the high-risk first-relapse cohort and 16.7% in the expansion cohort. All patients had minimal residual disease. Adverse events were acceptable except for interstitial lung disease and hypoxia in a patient in the expansion cohort, but addition of bortezomib to conventional chemotherapy did not produce obvious improvement in children with R/R-ALL.

Safety and efficacy of post-haematopoietic cell transplantation maintenance therapy with blinatumomab for relapsed/refractory CD19-positive B-cell acute lymphoblastic leukaemia: protocol for a phase I-II, multicentre, non-blinded, non-controlled trial (JPLSG SCT-ALL-BLIN21)

INTRODUCTION

Relapsed and refractory B-cell acute lymphoblastic leukaemia (R/R-B-ALL) is linked to a significant relapse rate after allogeneic haematopoietic cell transplantation (allo-HCT) in children, adolescents and young adults (CAYA). No standard treatment has been established to prevent relapse after allo-HCT for R/R-B-ALL, which is an unmet medical need. The administration of blinatumomab after allo-HCT is expected to enhance the antileukaemic effect on residual CD19-positive blasts by donor-derived CD3-positive T-cells.

METHODS AND ANALYSIS

The goal of this multicentre, open-label, uncontrolled, phase I-II clinical trial is to assess the safety and effectiveness of post-transplant maintenance therapy with blinatumomab for CAYA patients (25 years old or younger) with CD19-positive R/R-B-ALL who have received allo-HCT beyond first complete remission (CR) and have CR with haematological recovery between 30 and 100 days after allo-HCT. Eighty-five paediatric institutions in Japan are participating in this study. Forty-one patients will enrol within 2.25-year enrolment period and follow-up period is 1 year. The primary endpoints are the treatment completion rate for phase I study and the 1-year graft-versus-host disease-free/relapse-free survival rate for phase II study, respectively.

ETHICS AND DISSEMINATION

This research was approved by the Central Review Board at National Hospital Organization Nagoya Medical Center (Nagoya, Japan) on 21 January 2022 and was registered at the Japan Registry of Clinical Trials (jRCT) on 3 March 2022. Written informed consent is obtained from all patients and/or their guardians. The results of this study will be disseminated through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

jRCTs041210154.

CRISPR/Cas9-Mediated Induction of Relapse-Specific NT5C2 and PRPS1 Mutations Confers Thiopurine Resistance as a Relapsed Lymphoid Leukemia Model

6-Mercaptopurine (6-MP) is a key component in maintenance therapy for childhood acute lymphoblastic leukemia (ALL). Recent next-generation sequencing analysis of childhood ALL clarified the emergence of the relapse-specific mutations of the NT5C2 and PRPS1 genes, which are involved in thiopurine metabolism. In this scenario, minor clones of leukemia cells could acquire the 6-MP-resistant phenotype as a result of the NT5C2 or PRPS1 mutation during chemotherapy (including 6-MP treatment) and confer disease relapse after selective expansion. Thus, to establish new therapeutic modalities overcoming 6-MP resistance in relapsed ALL, human leukemia models with NT5C2 and PRPS1 mutations in the intrinsic genes are urgently required. Here, mimicking the initiation process of the above clinical course, we sought to induce two relapse-specific hotspot mutations (R39Q mutation of the NT5C2 gene and S103N mutation of the PRPS1 gene) into a human lymphoid leukemia cell line by homologous recombination (HR) using the CRISPR/Cas9 system. After 6-MP selection of the cells transfected with Cas9 combined with single-guide RNA and donor DNA templates specific for either of those two mutations, we obtained the sublines with the intended NT5C2-R39Q and PRPS1-S103N mutation as a result of HR. Moreover, diverse in-frame small insertion/deletions were also confirmed in the 6-MP-resistant sublines at the target sites of the NT5C2 and PRPS1 genes as a result of nonhomologous end joining. These sublines are useful for molecular pharmacological evaluation of the NT5C2 and PRPS1 gene mutations in the 6-MP sensitivity and development of therapy overcoming the thiopurine resistance of leukemia cells. SIGNIFICANCE STATEMENT: Mimicking the initiation process of relapse-specific mutations of the NT5C2 and PRPS1 genes in childhood acute lymphoblastic leukemia treated with 6-mercaptopurine (6-MP), this study sought to introduce NT5C2-R39Q and PRPS1-S103N mutations into a human lymphoid leukemia cell line by homologous recombination using the CRISPR/Cas9 system. In the resultant 6-MP-resistant sublines, the intended mutations and diverse in-frame small insertions/deletions were confirmed, indicating that the obtained sublines are useful for molecular pharmacological evaluation of the NT5C2 and PRPS1 gene mutations.

Translational advances in the treatment of childhood acute lymphoblastic leukemia: narrative review of current and emerging molecular and immunotherapies

Background and Objective

Acute lymphoblastic leukemia (ALL) is the most common hematologic malignancy of lymphoid origin in children. The prognosis for newly diagnosed ALL in the pediatric population is generally favorable, with a 5-year overall survival rate of more than 90%. Though conventional therapy has led to meaningful improvements in cure rates for new-onset pediatric ALL, one-third of patients still experience a relapse or refractory disease, contributing to a significant cause of pediatric cancer-related mortality.

Methods

An extensive literature review was undertaken via various databases of medical literature, focusing on both results of larger clinical trials, but also with evaluation of recent abstract publications at large hematologic conferences.

Key Content and Findings

Remission is achievable in most of these patients by re-induction with currently available therapies, but the long-term overall survival rate is deemed suboptimal and remains a therapeutic challenge. As part of never-ceasing efforts to improve pediatric ALL outcomes, newer modalities, including targeted molecular therapies as well as immunotherapy, and chimeric antigen receptor (CAR) T-cell therapy, are currently being employed to increase treatment effectiveness as well as lessen the side effects from conventional chemotherapy. These approaches explore the use of early genome-based disease characterization and medications developed against actionable molecular targets.

Conclusions

Additional clinical research is nonetheless required to learn more about the potentially harmful effects of targeted therapies and investigate the possibility of these agents replacing or decreasing the use of conventional chemotherapy in treating pediatric ALL.

Treatment outcomes in childhood acute lymphoblastic leukemia: 40-year experience from a single tertiary center in Thailand

Studies on the long-term treatment outcomes of childhood acute lymphoblastic leukemia (ALL) in resource-limited countries are scarce. The purpose of this study was to assess the evolution of survival outcomes of pediatric ALL in a tertiary care center in Thailand over a 40-year period. We retrospectively reviewed the medical records of pediatric patients who were diagnosed with ALL and treated at our center between June 1979 and December 2019. We classified the patients into 4 study periods depending on the therapy protocol used to treat the patients (period 1: 1979-1986, period 2: 1987-2005, period 3: 2006-2013, and period 4: 2014-2019). The Kaplan-Meier method was used to determine overall and event-free survival (EFS) for each group. The log-rank test was used to identify statistical differences. Over the study period, 726 patients with ALL were identified, 428 boys (59%) and 298 girls (41%), with a median age at diagnosis of 4.7 years (range: 0.2-15 years). The study periods 1, 2, 3, and 4 had 5-year EFS rates of 27.6%, 41.6%, 55.9%, and 66.4%, and 5-year overall survival (OS) rates of 32.8%, 47.8%, 61.5%, and 69.3%, respectively. From periods 1 to 4, both the EFS and OS rates increased significantly (p <. 0001). Age, study period, and white blood cell (WBC) count were all significant prognostic indicators for survival outcomes. The OS of patients with ALL treated in our center improved significantly over time from 32.8% in period 1 to 69.3% in period 4.

MiRNAs in Hematopoiesis and Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common kind of pediatric cancer. Although the cure rates in ALL have significantly increased in developed countries, still 15–20% of patients relapse, with even higher rates in developing countries. The role of non-coding RNA genes as microRNAs (miRNAs) has gained interest from researchers in regard to improving our knowledge of the molecular mechanisms underlying ALL development, as well as identifying biomarkers with clinical relevance. Despite the wide heterogeneity reveled in miRNA studies in ALL, consistent findings give us confidence that miRNAs could be useful to discriminate between leukemia linages, immunophenotypes, molecular groups, high-risk-for-relapse groups, and poor/good responders to chemotherapy. For instance, miR-125b has been associated with prognosis and chemoresistance in ALL, miR-21 has an oncogenic role in lymphoid malignancies, and the miR-181 family can act either as a oncomiR or tumor suppressor in several hematological malignancies. However, few of these studies have explored the molecular interplay between miRNAs and their targeted genes. This review aims to state the different ways in which miRNAs could be involved in ALL and their clinical implications.

Proteasome inhibition targets the KMT2A transcriptional complex in acute lymphoblastic leukemia

Rearrangments in Histone-lysine-N-methyltransferase 2A (KMT2Ar) are associated with pediatric, adult and therapy-induced acute leukemias. Infants with KMT2Ar acute lymphoblastic leukemia (ALL) have a poor prognosis with an event-free-survival of 38%. Herein we evaluate 1116 FDA approved compounds in primary KMT2Ar infant ALL specimens and identify a sensitivity to proteasome inhibition. Upon exposure to this class of agents, cells demonstrate a depletion of histone H2B monoubiquitination (H2Bub1) and histone H3 lysine 79 dimethylation (H3K79me2) at KMT2A target genes in addition to a downregulation of the KMT2A gene expression signature, providing evidence that it targets the KMT2A transcriptional complex and alters the epigenome. A cohort of relapsed/refractory KMT2Ar patients treated with this approach on a compassionate basis had an overall response rate of 90%. In conclusion, we report on a high throughput drug screen in primary pediatric leukemia specimens whose results translate into clinically meaningful responses. This innovative treatment approach is now being evaluated in a multi-institutional upfront trial for infants with newly diagnosed ALL.

Efficacy and safety of blinatumomab in children with relapsed/refractory B cell acute lymphoblastic leukemia: A systematic review and meta-analysis

Objectives: Several clinical trials have been conducted to evaluate the effects of blinatumomab in childhood B cell acute lymphoblastic leukemia (B-ALL). We conducted this meta-analysis to validate the efficacy and safety of blinatumomab in pediatric patients with relapsed/refractory B-ALL (R/R B-ALL). Methods: We searched and investigated all relevant studies in the PubMed, Web of Science, Embase, and Cochrane Library databases. The primary outcomes were complete response (CR), overall survival (OS), event free survival (EFS), minimal residual disease (MRD) response, allogeneic hematopoietic stem cell transplantation (allo-HSCT) and were calculated separately for randomized controlled trials (RCTs) and single-arm studies. The secondary end points were adverse effects (AEs) and the relapse rate. The Cochrane, bias assessment tool, was used to assess the risk of bias in RCTs. The methodological quality of single-arm studies was assessed using the methodological index for non-randomized studies (MINORS) tool. Results: The meta-analysis included two RCTs and 10 single-arm studies, including 652 patients in total. Our study showed that in the single-arm studies, the combined CR rate was 0.56 (95% confidence interval (CI): 0.45 -0.68), the odds ratios (ORs) of OS was 0.43 (95% CI 0.32 -0.54), the EFS rate was 0.30 (95% CI: 0.20 -0.40), the MRD response was 0.51 (95% CI: 0.34 -0.68), allo-HSCT rate was 0.62 (95% CI: 0.50 -.74), the AE rate was 0.65 (95% CI: 0.54 -0.76) and the relapse rate was 0.32 (95% CI: 0.27 -0.38). In the RCTs, the blinatumomab-treated group compared with the chemotherapy group had a combined OS rate of 0.12 (95% CI: 0.05 -0.19) and an EFS rate of 2.16 (95% CI: 1.54 -3.03). The pooled MRD response rate was 4.71 (95% CI:2.84 -7.81), allo-HSCT was 3.24 (95% CI: 1.96 -5.35), the AE rate was 0.31 (95% CI: 0.16 -0.60), and the relapse rate was 0 .69 (95% CI: 0.43 -1.09). Conclusion: According to this meta-analysis, blinatumomab shows potent therapeutic efficacy and limited AEs in children with R/R B- ALL. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42022361914.

A Review of CAR-T Therapy in Pediatric and Young Adult B-Lineage Acute Leukemia: Clinical Perspectives in Singapore

Approximately 10-15% of pediatric B-cell acute lymphoblastic leukemia (B-ALL) are high risk at diagnosis or relapsed/ refractory. Prior to the availability of chimeric antigen receptor T-cell (CAR-T) in Singapore and the region, the treatment options for these paediatric and young adults are conventional salvage chemotherapy or chemo-immunotherapy regimens as a bridge to allogeneic total body irradiation-based hematopoietic stem cell transplantation (allo-HSCT). This results in significant acute and long-term toxicities, with suboptimal survival outcomes. Finding a curative salvage therapy with fewer long-term toxicities would translate to improved quality-adjusted life years in these children and young adults. In this review, we focus on the burden of relapsed/refractory pediatric B-ALL, the limitations of current strategies, the emerging paradigms for the role of CAR-T in r/r B-ALL, our local perspectives on the health economics and future direction of CAR-T therapies in pediatric patients.

Phase 1b study of carfilzomib with induction chemotherapy in pediatric relapsed/refractory acute lymphoblastic leukemia

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most common cancer diagnosed in childhood. Survival for patients following relapse remains poor, and achieving complete remission (CR) after relapse is the first critical step to cure. Carfilzomib is a proteasome inhibitor with an acceptable safety profile and clinical activity in adults with multiple myeloma but has not been assessed in children. The primary objective of this phase 1b study was to assess the safety and tolerability of carfilzomib combined with vincristine, dexamethasone, asparaginase, and daunorubicin (VXLD) in children with relapsed and/or refractory ALL.

METHODS

Patients aged 1-21 years (n = 24) received 4-week induction therapy with carfilzomib at dose levels of 27 mg/m² (n = 3), 36 mg/m² (n = 7), 45 mg/m² (n = 4), and 56 mg/m² (n = 10) in combination with VXLD. Patients achieving stable disease were offered further consolidation chemotherapy. Analyses were based on the safety evaluable population.

RESULTS

Following dose escalation of carfilzomib, the recommended phase 2 carfilzomib dose was identified as 56 mg/m² . Grade ≥3 hematological adverse events were common (83%, 20/24 patients), and serious treatment-emergent adverse events occurred in 58% (14/24) of patients. At the end of induction, CR/CR with incomplete platelet recovery (CRp)/CR with incomplete blood count recovery (CRi) was identified in 50% of patients (n = 12/24). By the end of consolidation, cumulative CR/CRp/CRi was identified in 58% of patients (n = 14/24).

CONCLUSION

These data support the use of carfilzomib in pediatric patients with relapsed and/or refractory ALL.

Antileukemic properties of the kinase inhibitor OTSSP167 in T-cell acute lymphoblastic leukemia

Novel drugs are needed to increase treatment response in children with high-risk T-cell acute lymphoblastic leukemia (T-ALL). Following up on our previous report on the activation of the MAP2K7-JNK pathway in pediatric T-ALL, here we demonstrate that OTSSP167, recently shown to inhibit MAP2K7, has antileukemic capacity in T-ALL. OTSSP167 exhibited dose-dependent cytotoxicity against a panel of T-ALL cell lines with IC50 in the nanomolar range (10-50 nM). OTSSP167 induces apoptosis and cell cycle arrest in T-ALL cell lines, associated at least partially with the inhibition of MAP2K7 kinase activity and lower activation of its downstream substrate, JNK. Other leukemic T-cell survival pathways, such as mTOR and NOTCH1 were also inhibited. Daily intraperitoneal administration of 10 mg/kg OTSSP167 was well tolerated, with mice showing no hematological toxicity, and effective at reducing the expansion of human T-ALL cells in a cell-based xenograft model. The same dosage of OTSSP167 efficiently controlled the leukemia burden in the blood, bone marrow, and spleen of 3 patient-derived xenografts, which resulted in prolonged survival. OTSSP167 exhibited synergistic interactions when combined with dexamethasone, L-asparaginase, vincristine, and etoposide. Our findings reveal novel antileukemic properties of OTSSP167 in T-ALL and support the use of OTSSP167 as an adjuvant drug to increase treatment response and reduce relapses in pediatric T-ALL.

Real-world experience in treating pediatric relapsed/refractory or therapy-related myeloid malignancies with decitabine, vorinostat, and FLAG therapy based on a phase 1 study run by the TACL consortium

Current therapies for relapsed/refractory (R/R) pediatric myeloid neoplasms are inadequately effective. Real-world data (RWD) can improve care by augmenting traditional studies and include individuals not eligible for clinical trials. The Therapeutic Advances in Childhood Leukemia and Lymphoma (TACL) consortium recently completed T2016-003, a phase 1 study of decitabine, vorinostat, fludarabine, cytarabine, and granulocyte colony-stimulating factor (G-CSF) in R/R acute myeloid leukemia (AML), which added epigenetic drugs to a cytotoxic backbone. We report results of RWD from six centers that treated 28 pediatric patients (26 with AML, two with other myeloid neoplasms) identically to the TACL study but who were not enrolled. This allowed unique analyses and the ability to compare data with the 35 TACL study patients. The overall response rate (ORR) (complete response [CR] plus CR with incomplete count recovery) among 26 RWD evaluable patients was 65%. The ORR of 13 patients with relapsed AML with epigenetic alterations was 69% (T2016-003 + RWD: 68%, n = 25), of eight patients with refractory AML was 38% (T2016-003 + RWD: 41%, n = 17) and of five patients with therapy-related AML (t-AML) was 80% (T2016-003 + RWD: 75%, n = 8). The mean number of Grade 3/4 toxicities experienced by the T2016-003-eligible RWD population (n = 22) (one per patient-cycle) was not meaningfully different than those (n = 6) who would have been TACL study-ineligible secondary to comorbidities (two per patient-cycle). Overall, this therapy was well tolerated and effective in pediatric patients with R/R myeloid neoplasms, particularly those with epigenetic alterations, t-AML, and refractory disease.

Tisagenlecleucel for relapsed/refractory acute lymphoblastic leukemia in the Irish healthcare setting: cost-effectiveness and value of information analysis

OBJECTIVES

This study evaluates the cost-effectiveness of tisagenlecleucel (a CAR T-cell therapy), versus blinatumomab, for the treatment of pediatric and young adult patients with relapsed/refractory acute lymphoblastic leukemia (R/R ALL) in the Irish healthcare setting. The value of conducting further research, to investigate the value of uncertainty associated with the decision problem, is assessed by means of expected value of perfect information (EVPI) and partial EVPI (EVPPI) analyses.

METHODS

A three-state partitioned survival model was developed. A short-term decision tree partitioned patients in the tisagenlecleucel arm according to infusion status. Survival was extrapolated to 60 months; general population mortality with a standardized mortality ratio was then applied. Estimated EVPI and EVPPI were scaled up to population according to the incidence of the decision.

RESULTS

At list prices, the incremental cost-effectiveness ratio was EUR 73,086 per quality-adjusted life year (QALY) (incremental costs EUR 156,928; incremental QALYs 2.15). The probability of cost-effectiveness, at the willingness-to-pay threshold of EUR 45,000 per QALY, was 16 percent. At this threshold, population EVPI was EUR 314,455; population EVPPI was below EUR 100,000 for each parameter category.

CONCLUSIONS

Tisagenlecleucel is not cost effective, versus blinatumomab, for the treatment of pediatric and young adult patients with R/R ALL in Ireland (at list prices). Further research to decrease decision (parameter) uncertainty, at the defined willingness-to-pay threshold, may not be of value. However, there is a high degree of uncertainty underpinning the analysis, which may not be captured by EVPI analysis.

Anti-CCR9 chimeric antigen receptor T cells for T-cell acute lymphoblastic leukemia

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of immature T lymphocytes, associated with higher rates of induction failure compared with those in B cell acute lymphoblastic leukemia. The potent immunotherapeutic approaches applied in B cell acute lymphoblastic leukemia, which have revolutionized the treatment paradigm, have proven more challenging in T-ALL, largely due to a lack of target antigens expressed on malignant but not healthy T cells. Unlike B cell depletion, T-cell aplasia is highly toxic. Here, we show that the chemokine receptor CCR9 is expressed in >70% of cases of T-ALL, including >85% of relapsed/refractory disease, and only on a small fraction (<5%) of normal T cells. Using cell line models and patient-derived xenografts, we found that chimeric antigen receptor (CAR) T-cells targeting CCR9 are resistant to fratricide and have potent antileukemic activity both in vitro and in vivo, even at low target antigen density. We propose that anti-CCR9 CAR-T cells could be a highly effective treatment strategy for T-ALL, avoiding T cell aplasia and the need for genome engineering that complicate other approaches.

Bortezomib-based Anthracycline-free Induction for Pediatric Relapsed ALL as a Bridge to Immunotherapy

BACKGROUND

Immunotherapy may lead to durable remissions in patients with relapsed and refractory acute lymphoblastic leukemia (R/R ALL). Patients receiving immunotherapy with a lower disease burden tend to have improved long-term outcomes and less toxicity. Thus, an induction protocol to achieve lower disease burden is required. Bortezomib added to a 4-drug induction was shown to lead to high rates of remission in R/R ALL patients. Inclusion of anthracyclines in this protocol may preclude most patients, having maximized the cumulative dose of anthracyclines. Thus, our goal was to evaluate anthracycline-free bortezomib-based induction for patients with R/R ALL.

PROCEDURE

We conducted a retrospective analysis of patients treated with bortezomib-based protocols for R/R ALL between 2011 and 2019 at our center. Data regarding toxicity and response rate was collected and analyzed.

RESULTS

Eighteen children with R/R ALL were treated with bortezomib-based induction, 13 of them without anthracyclines. Eleven patients did not complete the induction course: 6 due to toxicity, and 5 due to physician decision to proceed to immunotherapy early. Two events of treatment-related mortality occurred. There was no significant difference in toxicity between patients who treated with anthracycline and those who were not. Ten patients achieved complete remission, with 4 patients having polymerase-chain-reaction minimal residual disease below 10-4. Fifteen patients proceeded directly to immunotherapy: 11 patients received CD19 chimeric-antigen receptor-T-cells, 2 blinatumomab and 2 hematopoietic stem cell transplant.

CONCLUSION

Anthracyclines can be safely omitted from bortezomib-based therapies in patients with R/R ALL, when planning to proceed to immunotherapy.

JAK3 mutations and mitochondrial apoptosis resistance in T-cell acute lymphoblastic leukemia

Resistance to mitochondrial apoptosis predicts inferior treatment outcomes in patients with diverse tumor types, including T-cell acute lymphoblastic leukemia (T-ALL). However, the genetic basis for variability in this mitochondrial apoptotic phenotype is poorly understood, preventing its rational therapeutic targeting. Using BH3 profiling and exon sequencing analysis of childhood T-ALL clinical specimens, we found that mitochondrial apoptosis resistance was most strongly associated with activating mutations of JAK3. Mutant JAK3 directly repressed apoptosis in leukemia cells, because its inhibition with mechanistically distinct pharmacologic inhibitors resulted in reversal of mitochondrial apoptotic blockade. Inhibition of JAK3 led to loss of MEK, ERK and BCL2 phosphorylation, and BH3 profiling revealed that JAK3-mutant primary T-ALL patient samples were characterized by a dependence on BCL2. Treatment of JAK3-mutant T-ALL cells with the JAK3 inhibitor tofacitinib in combination with a spectrum of conventional chemotherapeutics revealed synergy with glucocorticoids, in vitro and in vivo. These findings thus provide key insights into the molecular genetics of mitochondrial apoptosis resistance in childhood T-ALL, and a compelling rationale for a clinical trial of JAK3 inhibitors in combination with glucocorticoids for patients with JAK3-mutant T-ALL.

Cost-Effectiveness and Budget Impact Analyses of Tisagenlecleucel in Pediatric and Young Adult Patients with Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia from the Singapore Healthcare System Perspective

Purpose

Children and young adults with relapsed or refractory (r/r) acute lymphoblastic leukemia (ALL) have poor survival due to ineffective therapy options. The newly approved chimeric antigen receptor T-cell (CAR-T) therapy, tisagenlecleucel, has demonstrated improved survival but at a high up-front cost. The study aims to evaluate the cost-effectiveness and budget impact of tisagenlecleucel versus salvage chemotherapy regimen (SCR) or blinatumomab (BLN) for the treatment of pediatric and young adult patients with relapsed/refractory B-cell ALL from the Singapore healthcare system perspective.

Patients and Methods

A three-health state partitioned survival model was constructed to analyze the cost-effectiveness of tisagenlecleucel vs SCR/BLN with/without allogenic hematopoietic stem cell transplantation (allo-HSCT) over a lifetime period. Clinical efficacy for tisagenlecleucel, SCR and BLN were based on pooled data from ELIANA, ENSIGN and B2101J trials, the study by von Stackelberg et al 2011, and MT103-205 respectively. Medical costs from pre-treatment until terminal care, including treatment, side effects, follow-up, subsequent allo-HSCT and relapse, were considered. Incremental cost-effectiveness ratios (ICERs) were estimated as the incremental costs per quality-adjusted life-year (QALY) gain. Additionally, the financial impact of tisagenlecleucel introduction in Singapore was estimated, comparing the present treatment scenario (without tisagenlecleucel) with a future scenario (with tisagenlecleucel), over 5 years.

Results

In the base-case analysis, tisagenlecleucel treatment demonstrated cost-effectiveness with an ICER of S$45,840 (US$34,762) per QALY (vs SCR) and S$51,978 (US$39,315) per QALY (vs BLN). The estimated budget ranges from S$477,857 (US$361,438) to S$1.4 million (US$1.05 million) annually for the initial 5 years.

Conclusion

Tisagenlecleucel is likely to be a cost-effective treatment option with limited budget implications while treating r/r ALL patients who have failed at least 2 lines of prior therapies.

Selumetinib in combination with dexamethasone for the treatment of relapsed/refractory RAS-pathway mutated paediatric and adult acute lymphoblastic leukaemia (SeluDex): study protocol for an international, parallel-group, dose-finding with expansion phase I/II trial

INTRODUCTION

Event-free survival rates at 15 years for paediatric patients with relapsed/refractory acute lymphoblastic leukaemia (ALL) are 30%-50%, with 5-year survival for adult patients only 20%. Many patients with newly diagnosed and relapsed ALL harbour somatic RAS-signalling activation mutations. Induction therapy for ALL involves steroids, with preclinical data suggesting the combination of dexamethasone with the MEK1/2 inhibitor, selumetinib (ARRY-142886) has a synergistic anticancer effect.

METHODS AND ANALYSIS

The SeluDex trial is an international, parallel-group, dose-finding with expansion, phase I/II trial to assess the selumetinib/dexamethasone combination in adult and paediatric patients with relapsed/refractory, RAS pathway mutant ALL. The Cancer Research UK Clinical Trials Unit at University of Birmingham is the UK Coordinating Centre, with national hubs in Copenhagen, Denmark; Monza, Italy; Münster, Germany; Paris, France; and Utrecht, Netherlands. Patients with morphologically proven relapsed/refractory or progressive B-cell precursor or T-cell ALL, with demonstrated RAS pathway activating mutations are eligible. Adult patients are >18 years old, ECOG <2 and paediatric <18 years old, Lansky play scale ≥60% or Karnofsky score ≥60%. Phase I primary objective is the recommended phase II dose of selumetinib as defined by occurrence/non-occurrence of dose limiting toxicities using the continual reassessment method; phase II will evaluate preliminary antileukaemic activity of the combination, as defined by morphological response 28 days post-treatment using a Bayesian approach. Target recruitment is between 26 and 42 patients (minimum 13 and maximum 21 per group), depending the number of phase I patients included in phase II.

ETHICS AND DISSEMINATION

Medical ethical committees of all the participating countries have approved the study protocol; initial (UK) ethics approval (17/YH/0123) was granted by Yorkshire & The Humber-Leeds West Research Ethics Committee. Participants are required to provide written informed consent/assent. Results will be disseminated through national and international presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

ISRCTN92323261.

A Metabolic Reprogramming Amino Acid Polymer as an Immunosurveillance Activator and Leukemia Targeting Drug Carrier for T-Cell Acute Lymphoblastic Leukemia

Compromised immunosurveillance leads to chemotherapy resistance and disease relapse of hematological malignancies. Amino acid metabolism regulates immune responses and cancer; however, a druggable amino acid metabolite to enhance antitumor immunosurveillance and improve leukemia targeting-therapy efficacy remains unexplored. Here, an L-phenylalanine polymer, Metabolic Reprogramming Immunosurveillance Activation Nanomedicine (MRIAN), is invented to effectively target bone marrow (BM) and activate the immune surveillance in T-cell acute lymphoblastic leukemia (T-ALL) by inhibiting myeloid-derived suppressor cells (MDSCs) in T-ALL murine model. Stable-isotope tracer and in vivo drug distribution experiments show that T-ALL cells and MDSCs have enhanced cellular uptake of L-phenylalanine and MRIANs than normal hematopoietic cells and progenitors. Therefore, MRIAN assembled Doxorubicin (MRIAN-Dox) specifically targets T-ALL cells and MDSCs but spare normal hematopoietic cells and hematopoietic stem and progenitor cells with enhanced leukemic elimination efficiency. Consequently, MRIAN-Dox has reduced cardiotoxicity and myeloablation side effects in treating T-ALL mice. Mechanistically, MRIAN degrades into L-phenylalanine, which inhibits PKM2 activity and reduces ROS levels in MDSCs to disturb their immunosuppressive function and increase their differentiation toward normal myeloid cells. Overall, a novel amino acid metabolite nanomedicine is invented to treat T-ALL through the combination of leukemic cell targeting and immunosurveillance stimulation.

Anti-leukemic effect and molecular mechanism of 11-methoxytabersonine from Melodinus cochinchinensis via network pharmacology, ROS-mediated mitochondrial dysfunction and PI3K/Akt signaling pathway

Melodinus cochinchinensis (Lour.) Merr. is a Yunnan endemic folk medicine. Our previous study showed that 11-methoxytabersonine (11-MT) isolated from M. cochinchinensis has strong cytotoxicity on human T-ALL cells, but its molecular mechanism has not been studied. In current study, the cytotoxicity and possible mechanism of 11-MT on T-cell acute lymphoblastic leukemia was explored using network pharmacology and molecular biology techniques. 11-MT significantly inhibited the cell proliferations on different four human T-ALL cells (MOLT-4, Jurkat, CCRF-CEM, and CEM/C1 cells). 11-MT triggered ROS accumulation, calcium concentration and cell apoptosis, and decreased the mitochondrial membrane potential (MMP) in human T-ALL cells, especially MOLT-4 cells. Western blot analysis showed that it can induce MOLT-4 cell apoptosis by up-regulating PI3K/Akt signaling pathway. Therefore, 11-MT induces human T-ALL cells apoptosis via up-regulation of ROS-mediated mitochondrial dysfunction and down-regulation of PI3K/Akt/mTOR signaling pathway.

Blinatumomab In pediatric relapsed/refractory B-cell acute lymphoblastic leukemia: RIALTO expanded access study final analysis

The safety and efficacy of blinatumomab, a CD3/CD19-directed bispecific T-cell engager molecule, for treatment of pediatric relapsed/refractory B-cell precursor acute lymphoblastic leukemia (R/R B-ALL) were examined in an open-label, single-arm, expanded access study (RIALTO). Children (>28 days, <18 years) with CD19+ R/R B-ALL received up to five cycles of blinatumomab by continuous infusion (cycle: 4 weeks on/2 weeks off). The primary endpoint was incidence of adverse events. Secondary endpoints included complete response (CR) and measurable residual disease (MRD) response within the first two cycles, relapse-free survival (RFS), overall survival (OS) and allogeneic hematopoietic stem cell transplant (alloHSCT) after treatment. At final data cutoff (1/10/20), 110 patients were enrolled (median age, 8.5 years; 88% ≥5% blasts at baseline). Blinatumomab treatment resulted in a low incidence of grade 3-4 cytokine release syndrome (n=2 [1.8%]) and neurologic events (n=4 [3.6%]). No blinatumomab-related fatal adverse events were reported. The probability of response was not affected by the presence of cytogenetic/molecular abnormalities. Median OS was 14.6 months (95%CI: 11.0─not estimable) and was significantly greater for MRD responders versus MRD non-responders (not estimable vs 9.3; HR 0.18, 95%CI: 0.08─0.39). One-year OS probability was higher for patients who received alloHSCT versus without alloHSCT post-blinatumomab (87% versus 29%). Median RFS for MRD responders (n=57) was 8.0 months (95%CI:3.4─10.1) versus 2.8 months (95%CI: 0.3─9.2) for MRD non-responders (n=10). Of patients achieving CR after 2 cycles, 73.5% (95%CI: 61.4%-83.5%) proceeded to alloHSCT. These findings support the use of blinatumomab as a safe and efficacious treatment for pediatric R/R B-ALL. (ClinicalTrials.gov identifier NCT02187354).

Novel Treatments for Pediatric Relapsed or Refractory Acute B-Cell Lineage Lymphoblastic Leukemia: Precision Medicine Era

With the markedly increased cure rate for children with newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL), relapse and refractory B-ALL (R/R B-ALL) remain the primary cause of death worldwide due to the limitations of multidrug chemotherapy. As we now have a more profound understanding of R/R ALL, including the mechanism of recurrence and drug resistance, prognostic indicators, genotypic changes and so on, we can use newly emerging technologies to identify operational molecular targets and find sensitive drugs for individualized treatment. In addition, more promising and innovative immunotherapies and molecular targeted drugs that are expected to kill leukemic cells more effectively while maintaining low toxicity to achieve minimal residual disease (MRD) negativity and better bridge hematopoietic stem cell transplantation (HSCT) have also been widely developed. To date, the prognosis of pediatric patients with R/R B-ALL has been enhanced markedly thanks to the development of novel drugs. This article reviews the new advancements of several promising strategies for pediatric R/R B-ALL.

Inotuzumab ozogamicin as single agent in pediatric patients with relapsed and refractory acute lymphoblastic leukemia: results from a phase II trial

Inotuzumab Ozogamicin is a CD22-directed antibody conjugated to calicheamicin, approved in adults with relapsed or refractory (R/R) B cell acute lymphoblastic leukemia (BCP-ALL). Patients aged 1-18 years, with R/R CD22 + BCP-ALL were treated at the RP2D of 1.8 mg/m². Using a single-stage design, with an overall response rate (ORR) ≤ 30% defined as not promissing and ORR > 55% as expected, 25 patients needed to be recruited to achieve 80% power at 0.05 significance level. Thirty-two patients were enrolled, 28 were treated, 27 were evaluable for response. The estimated ORR was 81.5% (95%CI: 61.9-93.7%), and 81.8% (18/22) of the responding subjects were minimal residual disease (MRD) negative. The study met its primary endpoint. Median follow up of survivors was 16 months (IQR: 14.49-20.07). One year Event Free Survival was 36.7% (95% CI: 22.2-60.4%), and Overall Survival was 55.1% (95% CI: 39.1-77.7%). Eighteen patients received consolidation (with HSCT and/or CAR T-cells therapy). Sinusoidal obstructive syndrome (SOS) occurred in seven patients. MRD negativity seemed correlated to calicheamicin sensitivity in vitro, but not to CD22 surface expression, saturation, or internalization. InO was effective in this population. The most relevant risk was the occurrence of SOS, particularly when InO treatment was followed by HSCT.

Genetic and immunophenotypic diversity of acute leukemias in children

Acute leukemias are the most commonly diagnosed malignancies in children. Acute leukemias constitute a heterogeneous group of cancers resulting from clonal outgrowth and accumulation of immature precursor cells of different hematologic lineages. Cancerous transformation begins with disruption of cell maturation mechanisms triggered by particular environmental or endogenic factors, including innate and acquired immunodeficiencies as well as autoimmune diseases.

Research in the field of acute leukemias has revealed many possible genetic abnormalities in leukemic cells, including both structural and numerical aberrations. The former can produce some particular fusion genes, yielding fusion protein products which can have an oncogenic potential in hematopoietic cells. Some of them, including translocations resulting in fusion product formation BCR-ABL1 and different fusion products involving the KMT2A gene, are markers of adverse prognosis, whereas numerical aberrations with high hyperdiploidy and chromosome number exceeding 51 are markers of favorable prognosis. Detection of these aberrations already has a well-grounded clinical significance in acute lymphoblastic leukemia and plays an important role in patient risk stratification. The appearance of particular genetic changes often correlates with the expression of certain markers on the surface of leukemic cells. Determination of expression or lack of specific antigens, that is, immunophenotyping, is possible with the use of the flow cytometry technique. Flow cytometry is currently considered as a fast and broadly available technique which can provide clinically useful information in a relatively short time after biological specimen collection. Flow cytometry also enables appropriate classification of acute leukemias.

Indirect comparison of tisagenlecleucel and blinatumomab in pediatric relapsed/refractory acute lymphoblastic leukemia

This study provides the first patient-level data indirect comparison of tisagenlecleucel vs blinatumomab in R/R ALL.

Tisagenlecleucel was associated with a comparatively higher likelihood of achieving CR and a lower hazard of death than blinatumomab.

In the absence of head-to-head trials, an indirect-treatment comparison can estimate the treatment effect of tisagenlecleucel in comparison with blinatumomab on rates of complete remission (CR) and overall survival (OS) in patients with relapsed or primary refractory (R/R) acute lymphoblastic leukemia (ALL). Patient-level data from two pivotal trials, ELIANA (tisagenlecleucel; n = 79) and MT103-205 (blinatumomab; n = 70), were used in comparisons of CR and OS, controlling for cross-trial difference in available patient characteristics. Five different adjustment approaches were implemented: stabilized inverse probability of treatment weight (sIPTW); trimmed sIPTW; stratification by propensity score quintiles; adjustment for prognostic factors; and adjustment for both prognostic factors and propensity score. Comparative analyses indicate that treatment with tisagenlecleucel was associated with a statistically significant higher likelihood of achieving CR and lower hazard of death than treatment with blinatumomab. The tisagenlecleucel group exhibited a higher likelihood of CR than the blinatumomab group in every analysis regardless of adjustment approach (odds ratios: 6.71-9.76). Tisagenlecleucel was also associated with a lower hazard of death than blinatumomab in every analysis, ranging from 68% to 74% lower hazard of death than with blinatumomab, determined using multiple adjustment approaches (hazard ratios: 0.26-0.32). These findings support the growing body of clinical trials and real-world evidence demonstrating that tisagenlecleucel is an important treatment option for children and young adults with R/R ALL.

Multiple site place-of-care manufactured anti-CD19 CAR-T cells induce high remission rates in B-cell malignancy patients

Chimeric antigen receptor (CAR) T cells targeting the CD19 antigen are effective in treating adults and children with B-cell malignancies. Place-of-care manufacturing may improve performance and accessibility by obviating the need to cryopreserve and transport cells to centralized facilities. Here we develop an anti-CD19 CAR (CAR19) comprised of the 4-1BB co-stimulatory and TNFRSF19 transmembrane domains, showing anti-tumor efficacy in an in vivo xenograft lymphoma model. CAR19 T cells are manufactured under current good manufacturing practices (cGMP) at two disparate clinical sites, Moscow (Russia) and Cleveland (USA). The CAR19 T-cells is used to treat patients with relapsed/refractory pediatric B-cell Acute Lymphocytic Leukemia (ALL; n = 31) or adult B-cell Lymphoma (NHL; n = 23) in two independently conducted phase I clinical trials with safety as the primary outcome (NCT03467256 and NCT03434769, respectively). Probability of measurable residual disease-negative remission was also a primary outcome in the ALL study. Secondary outcomes include complete remission (CR) rates, overall survival and median duration of response. CR rates are 89% (ALL) and 73% (NHL). After a median follow-up of 17 months, one-year survival rate of ALL complete responders is 79.2% (95%CI 64.5‒97.2%) and median duration of response is 10.2 months. For NHL complete responders one-year survival is 92.9%, and median duration of response has not been reached. Place-of-care manufacturing produces consistent CAR-T cell products at multiple sites that are effective for the treatment of patients with B-cell malignancies.

Strategies to address the challenges associated with product manufacturing can improve chimeric antigen receptor (CAR) cell–based therapeutics. Here the authors report the results of two clinical trials in patients with B-cell malignancies, showing that place-of-care manufacturing has a low production failure rate with CD19-directed CAR-T cell products inducing high remission rates.

Optimizing the Clinical Impact of CAR-T Cell Therapy in B-Cell Acute Lymphoblastic Leukemia: Looking Back While Moving Forward

Chimeric antigen receptor T-cell (CAR-T) therapy has been successful in creating extraordinary clinical outcomes in the treatment of hematologic malignancies including relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). With several FDA approvals, CAR-T therapy is recognized as an alternative treatment option for particular patients with certain conditions of B-ALL, diffuse large B-cell lymphoma, mantle cell lymphoma, follicular lymphoma, or multiple myeloma. However, CAR-T therapy for B-ALL can be surrounded by challenges such as various adverse events including the life-threatening cytokine release syndrome (CRS) and neurotoxicity, B-cell aplasia-associated hypogammaglobulinemia and agammaglobulinemia, and the alloreactivity of allogeneic CAR-Ts. Furthermore, recent advances such as improvements in media design, the reduction of ex vivo culturing duration, and other phenotype-determining factors can still create room for a more effective CAR-T therapy in R/R B-ALL. Herein, we review preclinical and clinical strategies with a focus on novel studies aiming to address the mentioned hurdles and stepping further towards a milestone in CAR-T therapy of B-ALL.

Factors Impacting Overall and Event-Free Survival following Post-Chimeric Antigen Receptor T Cell Consolidative Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) may be used to consolidate chimeric antigen receptor (CAR) T cell therapy-induced remissions for patients with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL), but little is known about the factors impacting overall survival (OS) and event-free survival (EFS) for post-CAR hematopoietic stem cell transplantation (HSCT). The present study's primary objective was to identify factors associated with OS and EFS for consolidative HSCT following CAR-induced complete remission (CR) in transplantation-naïve patients. Secondary objectives included evaluation of OS/EFS, relapse-free survival and cumulative incidence of relapse for all patients who proceeded to HSCT, stratified by first and second HSCT, as well as the tolerability of HSCT following CAR-induced remission. This was a retrospective review of children and young adults enrolled on 1 of 3 CAR T cell trials at the National Cancer Institute targeting CD19, CD22, and CD19/22 (ClinicalTrials.gov identifiers NCT01593696, NCT02315612, and NCT03448393) who proceeded directly to HSCT following CAR T cell therapy. Between July 2012 and February 2021, 46 children and young adults with pre-B ALL went directly to HSCT following CAR therapy. Of these patients, 34 (74%) proceeded to a first HSCT, with a median follow-up of 50.8 months. Transplantation-naïve patients were heavily pretreated prior to CAR T cell therapy (median, 3.5 lines of therapy; range, 1 to 12) with significant prior immunotherapy exposure (blinatumomab, inotuzumab, and/or CAR T cell therapy in patients receiving CD22 or CD19/22 constructs (88%; 15 of /17)). Twelve patients (35%) had primary refractory disease, and the median time from CAR T cell infusion to HSCT Day 0 was 54.5 days (range, 42 to 127 days). The median OS following first HSCT was 72.2 months (95% confidence interval [CI], 16.9 months to not estimable [NE]), with a median EFS of 36.9 months (95% CI, 5.2 months to NE). At 12 and 24 months, the OS was 76.0% (95% CI, 57.6% to 87.2%) and 60.7% (95% CI, 40.8% to 75.8%), respectively, and EFS was 64.6% (95% CI, 46.1% to 78.1%) and 50.9% (95% CI, 32.6% to 66.6%), respectively. The individual factors associated with both decreased OS and EFS in univariate analyses for post-CAR consolidative HSCT in transplantation-naïve patients included ≥5 prior lines of therapy (not reached [NR] versus 12.4 months, P = .014; NR versus 4.8 months, P = .063), prior blinatumomab therapy (NR versus 16.9 months, P = .0038; NR versus 4.4 months, P = .0025), prior inotuzumab therapy (NR versus 11.5 months, P = .044; 36.9 months versus 2.7 months, P = .0054) and ≥5% blasts (M2/M3 marrow) pre-CAR T cell therapy (NR versus 17 months, P = .019; NR versus 12.2 months, P = .035). Primary refractory disease was associated with improved OS/EFS post-HSCT (NR versus 21.9 months, P = .075; NR versus 12.2 months, P = .024). Extensive prior therapy, particularly immunotherapy, and high disease burden each individually adversely impacted OS/EFS following post-CAR T cell consolidative HSCT in transplantation-naïve patients, owing primarily to relapse. Despite this, HSCT remains an important treatment modality in long-term cure. Earlier implementation of HSCT before multiply relapsed disease and incorporation of post-HSCT risk mitigation strategies in patients identified to be at high-risk of post-HSCT relapse may improve outcomes.

MCL-1 Inhibition Overcomes Anti-apoptotic Adaptation to Targeted Therapies in B-Cell Precursor Acute Lymphoblastic Leukemia

Multiple targeted therapies are currently explored for pediatric and young adult B-cell precursor acute lymphoblastic leukemia (BCP-ALL) treatment. However, this new armamentarium of therapies faces an old problem: choosing the right treatment for each patient. The lack of predictive biomarkers is particularly worrying for pediatric patients since it impairs the implementation of new treatments in the clinic. In this study, we used the functional assay dynamic BH3 profiling (DBP) to evaluate two new treatments for BCP-ALL that could improve clinical outcome, especially for relapsed patients. We found that the MEK inhibitor trametinib and the multi-target tyrosine kinase inhibitor sunitinib exquisitely increased apoptotic priming in an NRAS-mutant and in a KMT2A-rearranged cell line presenting a high expression of FLT3, respectively. Following these observations, we sought to study potential adaptations to these treatments. Indeed, we identified with DBP anti-apoptotic changes in the BCL-2 family after treatment, particularly involving MCL-1 - a pro-survival strategy previously observed in adult cancers. To overcome this adaptation, we employed the BH3 mimetic S63845, a specific MCL-1 inhibitor, and evaluated its sequential addition to both kinase inhibitors to overcome resistance. We observed that the metronomic combination of both drugs with S63845 was synergistic and showed an increased efficacy compared to single agents. Similar observations were made in BCP-ALL KMT2A-rearranged PDX cells in response to sunitinib, showing an analogous DBP profile to the SEM cell line. These findings demonstrate that rational sequences of targeted agents with BH3 mimetics, now extensively explored in clinical trials, may improve treatment effectiveness by overcoming anti-apoptotic adaptations in BCP-ALL.

Inhibition of the MAP2K7-JNK pathway with 5Z-7-oxozeaenol induces apoptosis in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive pediatric leukemia with a worse prognosis than most frequent B-cell ALL due to a high incidence of treatment failures and relapse. Our previous work showed that loss of the pioneer factor KLF4 in a NOTCH1-induced T-ALL mouse model accelerated the development of leukemia through expansion of leukemia-initiating cells and activation of the MAP2K7 pathway. Similarly, epigenetic silencing of the KLF4 gene in children with T-ALL was associated with MAP2K7 activation. Here, we showed the small molecule 5Z-7-oxozeaenol (5Z7O) induces dose-dependent cytotoxicity in a panel of T-ALL cell lines mainly through inhibition of the MAP2K7-JNK pathway, which further validates MAP2K7 as a therapeutic target. Mechanistically, 5Z7O-mediated apoptosis was caused by the downregulation of regulators of the G2/M checkpoint and the inhibition of survival pathways. The anti-leukemic capacity of 5Z7O was evaluated using leukemic cells from two mouse models of T-ALL and patient-derived xenograft cells generated using lymphoblasts from pediatric T-ALL patients. Finally, a combination of 5Z7O with dexamethasone, a drug used in frontline therapy, showed synergistic induction of cytotoxicity. In sum, we report here that MAP2K7 inhibition thwarts survival mechanisms in T-ALL cells and warrants future pre-clinical studies for high-risk and relapsed patients.

Outcomes and prognostic factors of adults with refractory or relapsed T-cell acute lymphoblastic leukemia included in measurable residual disease-oriented trials

Despite high complete remission (CR) rates with frontline therapy, relapses are frequent in adults with T-cell acute lymphoblastic leukemia (T-ALL) with limited salvage options. We analyzed the outcomes and prognostic factors for CR to salvage therapy and overall survival (OS) of patients with R/R T-ALL included in two prospective measurable residual disease-oriented trials. Seventy-five patients (70 relapsed, 5 refractory) were identified. Relapses occurred in bone marrow, isolated or combined in 50 patients, and in the central nervous system (CNS; isolated or combined) in 20. Second CR was attained in 30/75 patients (40%). Treatment with FLAG-Ida and isolated CNS relapse were independently associated with a higher CR rate after first salvage therapy. The median OS was 6.2 (95% confidence interval [CI], 3.9-8.6) months, with a 4-year OS probability of 18% (95% CI, 9%-27%). No differences in survival were observed according to the treatment with hematopoietic stem cell transplantation in patients in CR after first salvage therapy. Multivariable analysis showed a ≥12-month interval between first CR and relapse, CR after first salvage therapy and isolated CNS relapse as favorable prognostic factors for OS with hazard ratios (HR) (95% CI) of 1.931 (1.109-3.362), 2.958 (1.640-5.334), and 2.976 (1.157-7.655), respectively. This study confirms the poor outcomes of adults with R/R T-ALL among whom FLAG-Ida was the best of the rescue therapies evaluated. Late relapse, CR after first rescue therapy and isolated CNS relapse showed prognostic impact on survival. More effective rescue therapies are needed in adults with R/R T-ALL.

Have CD19-directed immunotherapy and haploidentical hematopoietic cell transplantation transformed pediatric B-cell acute lymphoblastic leukemia into a chronic disease?

The treatment of pediatric B-cell acute lymphoblastic leukemia (B-ALL) has undergone several recent advancements, leading to an increased amount of treatment options for relapsed patients. The development of immunotherapies such as anti-CD19 chimeric antigen receptor(CAR) T cells and bispecific T-cell engagers has given clinicians therapeutic options with less expected toxicity when compared to standard re-induction chemotherapy. This is especially beneficial in patients with toxicities from their prior treatment. Along with this, the emergence of haploidentical hematopoietic cell transplantation (HCT) has increased opportunity for patients to receive HCT who may not have had an available matched donor. We present four patients who have received all of these therapies in different combinations to treat multiple relapses. Because of the success of achieving remission as well as decreasing toxicity, the patients are alive and well up to 15 y after the original B-ALL diagnosis, rendering this as a chronic disease for them.

Current and emerging therapeutic approaches for T-cell acute lymphoblastic leukaemia

T-cell ALL (T-ALL) is an aggressive malignancy of T-cell progenitors. Although survival outcomes in T-ALL have greatly improved over the past 50 years, relapsed and refractory cases remain extremely challenging to treat and those who cannot tolerate intensive treatment continue to have poor outcomes. Furthermore, T-ALL has proven a more challenging immunotherapeutic target than B-ALL. In this review we explore our expanding knowledge of the basic biology of T-ALL and how this is paving the way for repurposing established treatments and the development of novel therapeutic approaches.

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

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

CD81 knockout promotes chemosensitivity and disrupts in vivo homing and engraftment in acute lymphoblastic leukemia

Relapse remains a major obstacle to achieving 100% overall survival rate in pediatric hematologic malignancies like acute lymphoblastic leukemia (ALL). Relapse often results from the development of chemoresistance. One of the mechanisms of chemoresistance involves ALL cell interactions with the bone marrow (BM) microenvironment, providing a sanctuary. This phenomenon is known as BM microenvironment-induced chemoprotection. Members of the transmembrane 4 superfamily (tetraspanins; TSPANs) are known to mediate microenvironmental interactions and have been extensively studied in solid tumors. Although the TSPAN family member CD81 is a minimal residual disease marker, its biological role in ALL is not well characterized. We show for the first time that CD81 knockout induces chemosensitivity, reduces cellular adhesion, and disrupts in vivo BM homing and engraftment in B-ALL. This chemosensitization is mediated through control of Bruton tyrosine kinase signaling and induction of p53-mediated cell death. We then show how CD81-related signaling can be disrupted by treatment with the epigenetic drug combination of DNA hypomethylating agent azacitidine (aza) and histone deacetylase inhibitor panobinostat (pano), which we previously used to sensitize ALL cells to chemotherapy under conditions that promote BM microenvironment-induced chemoprotection. Aza/pano-mediated modulation of CD81 surface expression is involved in decreasing BM load by promoting ALL cell mobilization from BM to peripheral blood and increasing response to chemotherapy in disseminated patient-derived xenograft models. This study identifies the novel role of CD81 in BM microenvironment-induced chemoprotection and delineates the mechanism by which aza/pano successfully sensitizes ALL cells via modulation of CD81.

Phase 1 study of bendamustine in combination with clofarabine, etoposide, and dexamethasone in pediatric patients with relapsed or refractory hematologic malignancies

BACKGROUND

A phase 1 study was conducted to determine the maximum tolerated dose of bendamustine when given in combination with clofarabine, etoposide, and dexamethasone daily for 5 days in children and adolescents with relapsed or refractory hematologic malignancies.

METHODS

Patients younger than 22 years with second or greater relapsed or refractory acute leukemia or lymphoma after 2 or more prior regimens were eligible. With the rolling 6 design, participants received escalating doses of bendamustine (30, 40, or 60 mg/m² /d) in combination with clofarabine (40 mg/m² ), etoposide (100 mg/m² ), and dexamethasone (8 mg/m² ) daily for 5 days. Optional pharmacokinetic studies were performed in cycle 1 on day 1 and day 5.

RESULTS

Sixteen patients were enrolled. Six patients were treated at the dose level of 30 mg/m² /d, 6 were treated at the dose level of 40 mg/m² /d, and 4 were treated at the dose level of 60 mg/m² /d. The dose-limiting toxicity was prolonged myelosuppression. The combination was otherwise well tolerated. The recommended dose of bendamustine in this combination was 30 mg/m² /d for 5 days. Ten responses were observed after 1 cycle: 6 complete remissions, 1 durable minimal residual disease-negative complete remission without platelet recovery in a patient with early T-cell precursor leukemia, and 3 partial remissions. Six patients proceeded to transplantation. The event-free survival rate was 40.6% (95% confidence interval [CI], 17.5%-63.7%) at 1 year and 33.9% (95% CI, 11.9%-55.9%) at 3 years.

CONCLUSIONS

Bendamustine is well tolerated in combination with clofarabine, etoposide, and dexamethasone. The combination administered over 5 days is effective for multiple relapsed and refractory hematologic malignancies. This trial is registered with ClinicalTrials.gov (NCT01900509).

LAY SUMMARY

Improvements to the existing chemotherapy regimen are still needed for patients who relapse after targeted therapies and immunotherapies and for those who are not eligible for or have no access to such therapies. A regimen combining cyclophosphamide, clofarabine, and etoposide has been used in relapsed and refractory pediatric patients with hematologic malignancies. This study shows that substituting bendamustine for cyclophosphamide in combination with clofarabine and etoposide is safe and effective.

Venetoclax and Navitoclax in Combination with Chemotherapy in Patients with Relapsed or Refractory Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma

Combining venetoclax, a selective BCL2 inhibitor, with low-dose navitoclax, a BCL-X_L/BCL2 inhibitor, may allow targeting of both BCL2 and BCL-X_L without dose-limiting thrombocytopenia associated with navitoclax monotherapy. The safety and preliminary efficacy of venetoclax with low-dose navitoclax and chemotherapy was assessed in this phase I dose-escalation study (NCT03181126) in pediatric and adult patients with relapsed/refractory (R/R) acute lymphoblastic leukemia or lymphoblastic lymphoma. Forty-seven patients received treatment. A recommended phase II dose of 50 mg navitoclax for adults and 25 mg for patients <45 kg with 400 mg adult-equivalent venetoclax was identified. Delayed hematopoietic recovery was the primary safety finding. The complete remission rate was 60%, including responses in patients who had previously received hematopoietic cell transplantation or immunotherapy. Thirteen patients (28%) proceeded to transplantation or CAR T-cell therapy on study. Venetoclax with navitoclax and chemotherapy was well tolerated and had promising efficacy in this heavily pretreated patient population. SIGNIFICANCE: In this phase I study, venetoclax with low-dose navitoclax and chemotherapy was well tolerated and had promising efficacy in patients with relapsed/refractory acute lymphoblastic leukemia or lymphoblastic lymphoma. Responses were observed in patients across histologic and genomic subtypes and in those who failed available therapies including stem cell transplant.See related commentary by Larkin and Byrd, p. 1324.This article is highlighted in the In This Issue feature, p. 1307.

Pediatric Acute Lymphoblastic Leukemia, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.

Paediatric relapsed acute leukaemia: curative intent chemotherapy improves quality of life

OBJECTIVES

Paediatric patients with leukaemia with relapse or induction failure have poor prognosis. Anticipated quality of life (QoL) is important in treatment decision making. The objective was to determine if curative intent at relapse or induction failure, when compared with palliative intent, was associated with child's physical health, pain or general fatigue and parents' QoL over time among patients with paediatric leukaemia in El Salvador.

METHODS

This was a prospective observational cohort study. Children 2-18 years with acute leukaemia at first relapse or induction failure were eligible. Assessments occurred every 2 months for up to 2 years using validated proxy report and self-report scales, where guardians were the primary respondents. Initial curative or palliative intent was categorised at enrolment by physicians. The impact of initial intent on QoL was assessed using linear mixed effects models and interaction between QoL and time.

RESULTS

Of the 60 families enrolled, initial treatment intent was curative in 31 (51.7%) and palliative in 29 (48.3%). During the 2-year observation period, 44 children died. Initial curative intent significantly improved child's physical health (estimate=8.4, 95% CI 5.1 to 11.6), pain (estimate=5.4, 95% CI 1.5 to 9.2) and fatigue (estimate=6.6, 95% CI 3.2 to 9.9) compared with palliative intent, but not parents' QoL (estimate=1.0, 95% CI -0.8 to 2.8).

CONCLUSIONS

Among paediatric patients with acute leukaemia at relapse or induction failure, initial curative intent treatment plan was associated with better physical health, pain and fatigue when compared with palliative intent. A curative approach may be a reasonable option for patients with acute leukaemia even when prognosis is poor.