Inotuzumab ozogamicin in pediatric patients with relapsed/refractory acute lymphoblastic leukemia

Inotuzumab ozogamicin combined with chemotherapy in pediatric B-cell precursor CD22+ acute lymphoblastic leukemia: results of the phase IB ITCC-059 trial

Inotuzumab ozogamicin (InO) is a CD22-directed antibody conjugated with calicheamicin. The phase IB of the ITCC-059 trial tested InO combined with chemotherapy in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Relapsed /refractory CD22+ BCP-ALL pediatric patients were enrolled. The primary objective was to establish the recommended phase II dose (RP2D). Secondary objectives included preliminary efficacy and tolerability. InO was combined with 1.5 mg/m2 of vincristine (days 3, 10, 17, 24), 20 mg/m2 of dexamethasone (2 5-day blocks, then amended), and intrathecal therapy. A rolling-6 design was used testing InO from 0.8 to 1.8 mg/m2/cycle. Between May 2020 and April 2022, 30 patients were treated, and 29 were evaluable for dose limiting toxicities (DLT). At 1.1 mg/m2/cycle, two of four patients had DLT (liver toxicity). InO was de-escalated to 0.8 mg/m2/cycle (N=6) without DLT while awaiting a protocol amendment to reduce dexamethasone dose to 10 mg/m2. Post amendment, InO was re-escalated to 1.1 mg/m2/cycle (N=6, 1 DLT), then to 1.4 mg/m2/ cycle (N=3, no DLT), and finally to 1.8 mg/m2/cycle (N=7, 1 DLT). Three additional patients were treated in an expansion cohort. The pooled response rate was 80% (24/30; 95% confidence interval [CI]: 61.4-92.3) and, among responders, 66.7% achieved minimal residual disease negativity. The RP2D of InO combined with vincristine, dexamethasone and intrathecal therapy was declared at 1.8 mg/m2/cycle (1.5 mg/m2/cycle after remission) in a fractioned schedule. This combination showed a response rate similar to the single agent cohorts of this trial, with liver toxicity issues at the initial higher dexamethasone dose (clinicaltrials gov. Identifier: NTR5736).

Down syndrome-associated leukaemias: current evidence and challenges

Children with Down syndrome (DS) are at increased risk of developing haematological malignancies, in particular acute megakaryoblastic leukaemia and acute lymphoblastic leukaemia. The microenvironment established by abnormal haematopoiesis driven by trisomy 21 is compounded by additional genetic and epigenetic changes that can drive leukaemogenesis in patients with DS. GATA-binding protein 1 (GATA1) somatic mutations are implicated in the development of transient abnormal myelopoiesis and the progression to myeloid leukaemia of DS (ML-DS) and provide a model of the multi-step process of leukaemogenesis in DS. This review summarises key genetic drivers for the development of leukaemia in patients with DS, the biology and treatment of ML-DS and DS-associated acute lymphoblastic leukaemia, late effects of treatments for DS-leukaemias and the focus for future targeted therapy.

Veno-Occlusive Disease: A Life-saving Novel Approach With Plasma Exchange, IVIG, and Steroid, Without Defibrotide

INTRODUCTION

Hepatic veno-occlusive disease (VOD) is a critical medical emergency with a high mortality rate of up to 90% if not promptly treated. Defibrotide is the only approved medication for VOD treatment, exhibiting anti-inflammatory, antithrombotic, and anti-ischemic properties. This report presents a case of severe VOD in a patient undergoing acute lymphoblastic leukemia (ALL) treatment.

CASE PRESENTATION

We describe the successful and rapid treatment of severe VOD in an ALL patient using therapeutic plasma exchange (TPE), intravenous immunoglobulin (IVIG), and methylprednisolone (MPZ). The patient showed significant clinical and laboratory improvement after this combined therapeutic approach.

CONCLUSION

This case highlights the effectiveness of TPE, IVIG, and MPZ in the treatment of severe VOD in ALL patients, providing insights into alternative therapeutic strategies in the absence of Defibrotide.

Inotuzumab Ozogamicin: First Pediatric Approval

Inotuzumab ozogamicin (BESPONSA™) is a CD22-targeted monoclonal antibody drug conjugate (ADC) developed by Pfizer for the treatment of CD22-postive B-cell precursor acute lymphoblastic leukaemia (ALL). Inotuzumab ozogamicin comprises a humanized IgG4 anti-CD22 monoclonal antibody covalently linked to the potent DNA-binding cytotoxic agent N-acetyl-gamma-calicheamicin dimethylhydrazide (CalichDMH) via a linker. Inotuzumab ozogamicin binds to CD22-expressing tumour cells, facilitating the delivery of conjugated CalichDMH, which after intracellular activation induces double strand DNA breaks, ultimately leading to cell cycle arrest and apoptotic cell death. Inotuzumab ozogamicin is approved in the USA, Europe and several countries worldwide for the treatment of relapsed or refractory CD22-positive B-cell precursor ALL in adults. On 6 March 2024, inotuzumab ozogamicin received its first pediatric approval in the USA for this indication in patients aged ≥ 1 years. Inotuzumab ozogamicin has since been approved in Japan in March 2024 for the same indication in pediatric patients. This article summarizes the milestones in the development of inotuzumab ozogamicin leading to this first approval for the treatment of relapsed or refractory CD22-positive B-cell precursor ALL in pediatric patients.

Acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is a haematological malignancy characterized by the uncontrolled proliferation of immature lymphoid cells. Over past decades, significant progress has been made in understanding the biology of ALL, resulting in remarkable improvements in its diagnosis, treatment and monitoring. Since the advent of chemotherapy, ALL has been the platform to test for innovative approaches applicable to cancer in general. For example, the advent of omics medicine has led to a deeper understanding of the molecular and genetic features that underpin ALL. Innovations in genomic profiling techniques have identified specific genetic alterations and mutations that drive ALL, inspiring new therapies. Targeted agents, such as tyrosine kinase inhibitors and immunotherapies, have shown promising results in subgroups of patients while minimizing adverse effects. Furthermore, the development of chimeric antigen receptor T cell therapy represents a breakthrough in ALL treatment, resulting in remarkable responses and potential long-term remissions. Advances are not limited to treatment modalities alone. Measurable residual disease monitoring and ex vivo drug response profiling screening have provided earlier detection of disease relapse and identification of exceptional responders, enabling clinicians to adjust treatment strategies for individual patients. Decades of supportive and prophylactic care have improved the management of treatment-related complications, enhancing the quality of life for patients with ALL.

Naked antibodies and antibody-drug conjugates: targeted therapy for childhood acute lymphoblastic leukemia

The treatment of childhood acute lymphoblastic leukemia (ALL) has reached overall survival rates exceeding 90%. The present and future challenges are to cure the remainder of patients still dying from disease, and to reduce morbidity and mortality in those who can be cured with standard-of-care chemotherapy by replacing toxic chemotherapy elements while retaining cure rates. With the novel therapeutic options introduced in the last years, including immunotherapies and targeted antibodies, the treatment of ALL is undergoing major changes. For B-cell precursor ALL, blinatumomab, an anti-CD19 bispecific antibody, has established its role in the consolidation treatment for both high- and standard-risk first relapse of ALL, in the presence of bone marrow involvement, and may also have an impact on the outcome of high-risk subsets such as infant ALL and Philadelphia chromosome-positive ALL. Inotuzumab ozogamicin, an anti-CD22 drug conjugated antibody, has demonstrated high efficacy in inducing complete remission in relapsed ALL, even in the presence of high tumor burden, but randomized phase III trials are still ongoing. For T-ALL the role of CD38-directed treatment, such as daratumumab, is gaining interest, but randomized data are needed to assess its specific benefit. These antibodies are currently being tested in patients with newly diagnosed ALL and may lead to major changes in the present paradigm of treatment of pediatric ALL. Unlike the past, lessons may be learned from innovations in adult ALL, in which more drastic changes are piloted that may need to be translated to pediatrics.

Relapsed Acute Lymphoblastic Leukemia

Outcomes for children with acute lymphoblastic leukemia (ALL) have improved worldwide to >85%. For those who relapse, outcomes have remained static at ~50% making relapsed acute lymphoblastic leukemia one of the leading causes of death in childhood cancers. Those relapsing within 18 mo in the bone marrow have a particularly dismal outcome. The mainstay of treatment is chemotherapy, local radiotherapy with or without hematopoietic stem cell transplantation (HSCT). Improved biological understanding of mechanisms of relapse and drug resistance, use of innovative strategies to identify the most effective and least toxic treatment regimens and global partnerships are needed to improve outcomes in these patients. Over the last decade, new therapeutic options and strategies have been developed for relapsed ALL including immunotherapies and cellular therapies. It is imperative to understand how and when to use these newer approaches in relapsed ALL. Increasingly, integrated precision oncology strategies are being used to individualize treatment of patients with relapsed ALL, especially in patients with poor response disease.

Primary Budd-Chiari syndrome versus sinusoidal obstruction syndrome: a review

Budd-Chiari syndrome (BCS) and sinusoidal obstruction syndrome (SOS) are two major vascular disorders of the liver, of which both can cause portal hypertension related complications, but their locations of obstruction are different. BCS refers to the obstruction from the hepatic vein to the junction between the inferior vena cava and right atrium, which is the major etiology of post-sinusoidal portal hypertension; by comparison, SOS is characterized as the obstruction at the level of hepatic sinusoids and terminal venulae, which is a cause of sinusoidal portal hypertension. Both of them can cause hepatic congestion with life-threatening complications, especially acute liver failure and chronic portal hypertension, and share some similar features in terms of imaging and clinical presentations, but they have heterogeneous risk factors, management strategy, and prognosis. Herein, this paper reviews the current evidence and then summarizes the difference between primary BCS and SOS in terms of risk factors, clinical features, diagnosis, and treatment.

Standardization of flow cytometric detection of antigen expression

Since response to antigen-based immunotherapy relies upon the level of tumor antigen expression we developed an antigen quantification assay using ABC values. Antigen quantification as a clinical assay requires methods for quality control and for interlaboratory and inter-cytometer platform standardization. A single lot of Cytotrol™ Lyophilized Control Cells (Beckman Coulter) used for all studies. The variability in antigen quantification across 4 different instrument platforms in 2 separate laboratories was evaluated. The effect of the antibody clone utilized, importance of custom 1:1 molar ratio (fluorophore to protein, F/P) verses off-the-shelf antibodies, and QuantiBrite PE calibration verses linearity calibration combined with a single point scale transformation with CD4 as reference were determined. Use of single lot control cells allowed validation of reproducibility between flow cytometer platforms and laboratories and allowed assessment of different antibody lots, cocktail preparation, and different antibody clones. Off the shelf antibody preparations provide reproducible estimates of antigen density, however custom 1:1 unimolar antibody preparations should be utilized for definitive measurement of antigen expression.Geometric Mean fluorescent Intensity (GeoMFI) was not comparable across instruments and inter-laboratory. The use of CD4 as the reference marker can minimize variability in ABC values. Comparable antigen quantification is vital in managing patients receiving antigen-based immunotherapy. If this assay is to be utilized in a clinical setting, quality control methods have to be instituted to assure reproducibility and allow validation across laboratories. We have demonstrated that use of a lyophilized cell control is highly valuable in achieveing these goals.

Selection of a novel cell-internalizing RNA aptamer specific for CD22 antigen in B cell acute lymphoblastic leukemia

Despite improvements in B cell acute lymphoblastic leukemia (B-ALL) treatment, a significant number of patients experience relapse of the disease, resulting in poor prognosis and high mortality. One of the drawbacks of current B-ALL treatments is the high toxicity associated with the non-specificity of chemotherapeutic drugs. Targeted therapy is an appealing strategy to treat B-ALL to mitigate these toxic off-target effects. One such target is the B cell surface protein CD22. The restricted expression of CD22 on the B-cell lineage and its ligand-induced internalizing properties make it an attractive target in cases of B cell malignancies. To target B-ALL and the CD22 protein, we performed cell internalization SELEX (Systematic Evolution of Ligands by EXponential enrichment) followed by molecular docking to identify internalizing aptamers specific for B-ALL cells that bind the CD22 cell-surface receptor. We identified two RNA aptamers, B-ALL1 and B-ALL2, that target human malignant B cells, with B-ALL1 the first documented RNA aptamer interacting with the CD22 antigen. These B-ALL-specific aptamers represent an important first step toward developing novel targeted therapies for B cell malignancy treatments.

Inotuzumab ozogamicin in B-cell precursor acute lymphoblastic leukemia: efficacy, toxicity, and practical considerations

Inotuzumab ozogamicin (InO) is an antibody drug conjugate composed of a humanized monoclonal antibody targeting the cell surface receptor CD22 coupled to a cytotoxic calicheamicin payload via an acid labile linker. InO has shown significant activity in relapsed and refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in both single agent and combination chemotherapy regimens in adult and pediatric trials. Its use in newly diagnosed elderly patients has also been established while clinical trials investigating its use in newly diagnosed pediatric patients and fit adults are ongoing. Notable toxicities include sinusoidal obstruction syndrome (SOS), particularly in patients who undergo hematopoietic stem cell transplantation (HSCT) after InO as well as myelosuppression and B-cell aplasia which confer increased infection risk, particularly in combination with cytotoxic chemotherapy. In the relapsed/refractory (R/R) setting, the planned subsequent curative therapy modality must be considered when using InO to mitigate SOS risk if proceeding to HSCT and account for potential B-cell aplasia if proceeding to chimeric antigen receptor CAR-T therapy. Studies exploring mechanisms of resistance or failure of InO are ongoing but modulation or loss CD22 expression, alternative CD22 splicing, and high Bcl-2 expression have been implicated. In this review, we will summarize the currently available data on InO, with an emphasis on pediatric trials, and explore future directions including combinatorial therapy.

Harnessing the Immune System: Current and Emerging Immunotherapy Strategies for Pediatric Acute Lymphoblastic Leukemia

Treatment for relapsed acute lymphoblastic leukemia (ALL) in children and young adults continues to evolve. Despite optimization of cytotoxic chemotherapeutic approaches and risk-adapted therapy, about 12% of pediatric patients still relapse, and survival rates in this population remain poor. Salvage therapy for relapsed patients continues to be challenging as attempts to further intensify chemotherapy have resulted in excessive toxicity without improving outcomes. Immunotherapy has profoundly impacted the landscape of relapsed ALL by harnessing the patient's immune system to target and eliminate leukemia cells. In this review, we provide an overview and summary of immunotherapy agents that have been approved and remain under investigation for children, including blinatumomab, inotuzumab, daratumomab, and chimeric antigen receptor T-cell therapy. We discuss the landmark clinical trials that have revolutionized the field and provide an update on ongoing clinical trials involving these agents for children in the relapsed and upfront setting. The incorporation of these novel immunotherapies into ALL treatment, either as monotherapy or in combination with cytotoxic chemotherapy, has demonstrated promising potential to augment outcomes while decreasing toxicity. However, we also highlight the many challenges we still face and the research critically needed to achieve our goals for cure in children.

Modern treatment strategies in pediatric oncology and hematology

Every year, approximately 400 00 children worldwide are diagnosed with cancer. Although treatment results in most types of childhood neoplasms are excellent with survival more than 80%, there are some with poor prognosis. Also recurrent and resistant to treatment childhood cancer remain a therapeutic challenge. Besides chemotherapy, which has been the basis of cancer therapy for years, molecular methods and precisely targeted therapies have recently found their usage. As a result of that, survival has improved and has positively impacted the rate of toxicities associated with chemotherapy (Butler et al. in CA Cancer J Clin 71:315-332, 2021). These achievements have contributed to better quality of patients' lives. Current methods of treatment and ongoing trials give hope for patients with relapses and resistance to conventional chemotherapy. This review focuses on the most recent progress in pediatric oncology treatments and discusses specific therapy methods for particular cancers types of cancer. Targeted therapies and molecular approaches have become more beneficial but research need to be continued in this field. Despite significant breakthroughs in pediatric oncology in the last few years, there is still a need to find new and more specific methods of treatment to increase the survival of children with cancer.

What is Next in Pediatric B-cell Precursor Acute Lymphoblastic Leukemia

Cure rates now exceed 90% in many contemporary trials for children with B-cell acute lymphoblastic leukemia (ALL). However, treatment remains suboptimal and therapy is toxic for all patients. New treatment options potentially offer the chance to reduce both treatment resistance and toxicity. Here, we review recent advances in ALL diagnostics, chemotherapy, and immunotherapy. In addition to describing recently published results, we also attempt to project the impact of these new developments into the future to imagine what B-ALL therapy may look like in the next few years.

Outcomes of Childhood Noninfant Acute Lymphoblastic Leukemia With 11q23/KMT2A Rearrangements in a Modern Therapy Era: A Retrospective International Study

PURPOSE

We aimed to study prognostic factors and efficacy of allogeneic hematopoietic stem-cell transplantation (allo-HSCT) in first remission of patients with noninfant childhood acute lymphoblastic leukemia (ALL) with 11q23/KMT2A rearrangements treated with chemotherapy regimens between 1995 and 2010.

PATIENTS AND METHODS

Data were retrospectively retrieved from 629 patients with 11q23/KMT2A-rearranged ALL from 17 members of the Ponte-di-Legno Childhood ALL Working Group. Clinical and biologic characteristics, early response assessed by minimal residual disease at the end of induction (EOI) therapy, and allo-HSCT were analyzed for their impact on outcomes.

RESULTS

A specific 11q23/KMT2A translocation partner gene was identified in 84.3% of patients, with the most frequent translocations being t(4;11)(q21;q23) (n = 273; 51.5%), t(11;19)(q23;p13.3) (n = 106; 20.0%), t(9;11)(p21_22;q23) (n = 76; 14.3%), t(6;11)(q27;q23) (n = 20; 3.8%), and t(10;11)(p12;q23) (n = 14; 2.6%); 41 patients (7.7%) had less frequently identified translocation partner genes. Patient characteristics and early response varied among subgroups, indicating large biologic heterogeneity and diversity in therapy sensitivity among 11q23/KMT2A-rearranged ALL. The EOI remission rate was 93.2%, and the 5-year event-free survival (EFS) for the entire cohort was 69.1% ± 1.9%, with a range from 41.7% ± 17.3% for patients with t(9;11)-positive T-ALL (n = 9) and 64.8% ± 3.0% for patients with t(4;11)-positive B-ALL (n = 266) to 91.2% ± 4.9% for patients with t(11;19)-positive T-ALL (n = 34). Low EOI minimal residual disease was associated with favorable EFS, and induction failure was particularly predictive of nonresponse to further therapy and relapse and poor EFS. In addition, EFS was not improved by allo-HSCT compared with chemotherapy only in patients with both t(4;11)-positive B-ALL (n = 64 v 51; P = .10) and 11q23/KMT2A-rearranged T-ALL (n = 16 v 10; P = .69).

CONCLUSION

Compared with historical data, prognosis of patients with noninfant 11q23/KMT2A-rearranged ALL has improved, but allo-HSCT failed to affect outcome. Targeted therapies are needed to reduce relapse and treatment-related mortality rates.

Pediatric Acute Lymphoblastic Leukemia Emerging Therapies-From Pathway to Target

Over the past 40 years, the 5-years-overall survival rate of pediatric cancer reached 75-80%, and for acute lymphoblastic leukemia (ALL), exceeded 90%. Leukemia continues to be a major cause of mortality and morbidity for specific patient populations, including infants, adolescents, and patients with high-risk genetic abnormalities. The future of leukemia treatment needs to count better on molecular therapies as well as immune and cellular therapy. Advances in the scientific interface have led naturally to advances in the treatment of childhood cancer. These discoveries have involved the recognition of the importance of chromosomal abnormalities, the amplification of the oncogenes, the aberration of tumor suppressor genes, as well as the dysregulation of cellular signaling and cell cycle control. Lately, novel therapies that have already proven efficient on relapsed/refractory ALL in adults are being evaluated in clinical trials for young patients. Tirosine kinase inhibitors are, by now, part of the standardized treatment of Ph+ALL pediatric patients, and Blinatumomab, with promising results in clinical trials, received both FDA and EMA approval for use in children. Moreover, other targeted therapies such as aurora-kinase inhibitors, MEK-inhibitors, and proteasome-inhibitors are involved in clinical trials that include pediatric patients. This is an overview of the novel leukemia therapies that have been developed starting from the molecular discoveries and those that have been applied in pediatric populations.

The Choice of Either Conventional Chemotherapy or Inotuzumab Ozogamicin as Bridging Regimen Does Not Appear To Impact Clinical Response to CD19-Directed CAR-T Therapy in Pediatric B-ALL

Bridging therapy (BT) given during the period between T-cell collection and initiation of lymphodepleting chemotherapy is indicated for most children with B-cell acute lymphoblastic leukemia (B-ALL) undergoing treatment with tisagenlecleucel (tisa-cel), a CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy. Both conventional chemotherapy agents and B-cell directed antibody-based therapies such as antibody-drug conjugates and bispecific T-cell engagers have been used as systemic forms of BT. The purpose of this retrospective study was to evaluate if there are detectable differences in clinical outcomes based on the type of BT given (conventional chemotherapy or inotuzumab). A retrospective analysis was performed on all patients treated with tisa-cel at Cincinnati Children's Hospital Medical Center for B-ALL with bone marrow disease (with or without extramedullary disease). Patients who did not receive systemic BT were excluded. Only 1 patient received blinatumomab as BT and was therefore not included in this analysis to focus the analysis on the use of inotuzumab. Pre-infusion characteristics and post-infusion outcomes were collected. Fisher's exact test was used for categorical variables, and t-test or Mann-Whitney test was used for continuous parametric and non-parametric variables respectively. Mantel-Cox was used for survival analyses. Thirty-two patients received BT before CD19 CAR-T for medullary leukemia; 24 received conventional chemotherapy, and 8 received inotuzumab ozogamicin (InO). Cohorts were evenly matched regarding CAR-T indication, recipient age, and median CAR-T cell dose. There were no significant differences between the groups for attaining a minimal residual disease (MRD)-negative complete response after CAR-T, the percentage of patients who maintained prolonged B-cell aplasia, or the median duration of B-cell aplasia. Thirty-seven percent of patients in the conventional chemotherapy group and 43% in the antibody-based therapy group relapsed, with a median time to relapse in both groups of 5 months. No differences in event-free survival, the cumulative incidence of relapse, or overall survival were seen between the two groups. Initial response to tisa-cel, relapse rate, and survival were similar between patients who received BT with conventional chemotherapy or InO therapy. Because low disease burden at the time of infusion is a positive prognostic factor, choice of bridging regimen should focus on therapy that is anticipated to effectively lower disease burden and minimize treatment-related toxicity. Given the limitations associated with the single center retrospective analysis, a larger, multicenter study is needed to further explore these findings.

HLA-haploidentical hematopoietic stem cells transplantation with regulatory and conventional T-cell adoptive immunotherapy in pediatric patients with very high-risk acute leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) is still needed for many children with very high-risk acute leukemia. An HLA-haploidentical family donor is a suitable option for those without an HLA-matched donor. Here we present outcomes of a novel HLA-haploidentical HSCT (haplo-HSCT) strategy with adoptive immunotherapy with thymic-derived CD4⁺CD25⁺ FoxP3⁺ regulatory T cells (Tregs) and conventional T cells (Tcons) performed between January 2017 and July 2021 in 20 children with high-risk leukemia. Median age was 14.5 years (range, 4-21), 15 had acute lymphoblastic leukemia, 5 acute myeloid leukemia. The conditioning regimen included total body irradiation (TBI), thiotepa, fludarabine, cyclophosphamide. Grafts contained a megadose of CD34+ cells (mean 12.4 × 10⁶/Kg), Tregs (2 × 10⁶/Kg) and Tcons (0.5-1 × 10⁶/Kg). All patients achieved primary, sustained full-donor engraftment. Only one patient relapsed (5%). The incidence of non-relapse mortality was 15% (3/20 patients). Five/20 patients developed ≥ grade 2 acute Graft versus Host Disease (aGvHD). It resolved in 4 who are alive and disease-free; 1 patient developed chronic GvHD (cGvHD). The probability of GRFS was 60 ± 0.5% (95% CI: 2.1-4.2) (Fig. 6), CRFS was 79 ± 0.9% (95% CI: 3.2-4.9) as 16/20 patients are alive and leukemia-free. The median follow-up was 2.1 years (range 0.5 months-5.1 years). This innovative approach was associated with very promising outcomes of HSCT strategy in pediatric patients.

Outcome of chimeric antigen receptor T-cell therapy following treatment with inotuzumab ozogamicin in children with relapsed or refractory acute lymphoblastic leukemia

Chimeric antigen receptor T cells targeting CD19 (CART-19) have shown remarkable efficacy for relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL). We investigated whether prior use of inotuzumab ozogamicin (InO), an anti-CD22 antibody conjugated to calicheamicin, may impact CAR T-cell manufacturing or efficacy via pre-CART-19 depletion of the B-cell compartment. In this international, retrospective analysis, 39 children and young adults receiving InO before (n = 12) and/or after (n = 27) T-cell apheresis as bridging therapy to CART-19 treatment were analyzed. Median age at infusion was 13 years (range 1.4-23 years). Thirty-four out of 39 patients (87.2%) obtained complete remission. With a median follow-up of 18.2 months after CART-19 infusion, 12-month event-free survival (EFS) was 53.3% (95% confidence interval (CI): 38.7-73.4) and overall survival (OS) was 77.8% (95% CI: 64.5-93.9). Seventeen patients (44%) relapsed with a median of 159 days (range 28-655) after CART-19 infusion. No difference in day 28 minimal residual disease negative complete response rate, 12-month OS/EFS, or incidence of CD19-positive or -negative relapses was observed among patients receiving InO before or after apheresis. Compared to published data for patients treated with CART-19 therapy without prior InO exposure, response and OS/EFS for patients treated with InO prior to CART-19 are similar.

The prognostic effect on childhood acute lymphoblastic leukemia of CD34+CD38- expressed in leukemia cells

OBJECTIVE

Acute lymphoblastic leukemia is the most common malignant disease in children. CD34 and CD38 are expressed in both normal and leukemia cells, but studies of their prognostic associations in childhood acute lymphoblastic leukemia are limited. The aim of this study was to investigate the prognostic effect of CD34 ⁺CD38^- leukemia cells in this childhood cancer.

METHODS

From January 2014 to January 2019, children with newly diagnosed acute lymphoblastic leukemia were included in this study and followed up until July 2020. The participants were divided into CD34⁺ and CD34^- groups according to CD34 expression level at diagnosis, and the CD34⁺ group was further divided into CD34 ⁺CD38^- and CD34 ⁺CD38⁺ subgroups based on CD38 expression level. We tracked clinical biological features, therapeutic outcomes, and other patient data for comparisons.

RESULTS

The OS and EFS did not differ significantly between the CD34⁺ and CD34^- groups (both P > 0.05). CD34⁺CD38^- group and CD34⁺CD38⁺ group were further compared. OS differed significantly between these two groups (χ²= 3.89, P = 0.048), as did the recurrence rate (χ²= 5.04, P = 0.025), but EFS did not (χ²= 1.45, P > 0.05). Survival analysis in patients with recurrence showed a significantly higher OS for the CD34 ⁺CD38⁺ group compared with the CD34 ⁺CD38^- group (χ²= 5.08, P = 0.024). The CD34⁺CD38^- group and CD34⁺CD38⁺ group were matched for propensity scores. When recurrence was compared in the two groups after matching, the difference was statistically significant (P < 0.001).

CONCLUSION

CD34⁺ and CD34^- expression does not differ by prognosis in children with acute lymphoblastic leukemia, but CD34 ⁺CD38^- may indicate a poor prognosis.

De Novo design of a humanized antiCD33 antibody-oridonin conjugate for acute myeloid leukemia therapy

Acute myeloid leukemia (AML) is the most common blood cancer in adults. Patients' 5-year overall survival is less than 30% thus having a poor prognosis. To date, the development of novel target therapies is still necessary to ameliorate patients' survival. Antibody-drug conjugates (ADCs) represent a promising class of drugs for the treatment of AML. CD33 is highly expressed on AML cells, and the FDA-approved CD33-targeted ADC drug-gemtuzumab ozogamicin (GO) has proved the feasibility of CD33-targeted ADC drug design. In this study, we constructed a novel CD33-targeted ADC drug composed of a humanized anti-CD33 antibody and oridonin as a payload with a cleaved chemical linker. Oridonin is a natural product that has great cancer therapy potential while its poor bioavailability and targeting ability limited its clinical use. Herein, we demonstrated that antiCD33-oridonin specifically delivered oridonin in AML cells improved AML cells killing ability of oridonin. Meanwhile, it did not show any non-specific toxicity on CD33 negative cells. In summary, we developed a novel AML targeting ADC with clinical application potential, and therefore provided a new solution for the druggability improvement of oridonin.

Infectious Complications of Targeted Therapies in Children with Leukemias and Lymphomas

Simple Summary

Targeted therapies in children with hematological malignancies moderate the effects of cytotoxic therapy, thus improving survival rates. They have emerged over the last decade and are used in combination with or after the failure of conventional chemotherapy and as bridging therapy prior to hematopoietic stem cell transplantation (HSCT). Nowadays, there is a growing interest in their efficacy and safety in pediatric patients with refractory or relapsed disease. The compromised immune system, even prior to therapy, requires prompt monitoring and treatment. In children with hematological malignancies, targeted therapies are associated with a comparable incidence of infectious complications to adults. The exact impact of these agents that have different mechanisms of action and are used after conventional chemotherapy or HSCT is difficult to ascertain. Clinicians should be cautious of severe infections after the use of targeted therapies, especially when used in combination with chemotherapy.

Abstract

The aim of this review is to highlight mechanisms of immunosuppression for each agent, along with pooled analyses of infectious complications from the available medical literature. Rituximab confers no increase in grade ≥3 infectious risks, except in the case of patients with advanced-stage non-Hodgkin lymphoma. Gemtuzumab ozogamicin links with high rates of grade ≥3 infections which, however, are comparable with historical cohorts. Pembrolizumab exhibits a favorable safety profile in terms of severe infections. Despite high rates of hypogammaglobulinemia (HGG) with blinatumomab, low-grade ≥3 infection rates were observed, especially in the post-reinduction therapy of relapsed B-acute lymphoblastic leukemia. Imatinib and nilotinib are generally devoid of severe infectious complications, but dasatinib may slightly increase the risk of opportunistic infections. Data on crizotinib and pan-Trk inhibitors entrectinib and larotrectinib are limited. CAR T-cell therapy with tisagenlecleucel is associated with grade ≥3 infections in children and is linked with HGG and the emergence of immune-related adverse events. Off-label therapies inotuzumab ozogamicin, brentuximab vedotin, and venetoclax demonstrate low rates of treatment-related grade ≥3 infections, while the addition of bortezomib to standard chemotherapy in T-cell malignancies seems to decrease the infection risk during induction. Prophylaxis, immune reconstitution, and vaccinations for each targeted agent are discussed, along with comparisons to adult studies.

Healthcare utilization and costs associated with acute lymphoblastic leukemia in children with and without Down syndrome

BACKGROUND

Children with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) are at increased risk of treatment-related morbidity and mortality compared to non-DS-ALL, requiring increased supportive care. We examined the healthcare utilization and costs in DS-ALL patients to inform future evaluations of novel therapies.

METHODS

A provincial registry identified all children (1-17 years) diagnosed with B-lineage ALL in Ontario, Canada between 2002 and 2012. Detailed demographic, disease, treatment, and outcome data were abstracted. Linkage to population-based health services databases identified all outpatient and emergency department (ED) visits, hospitalizations, and physician billings. Healthcare utilization costs were available for patients diagnosed during 2006-2012 using validated algorithms (2018 Canadian dollars). Healthcare utilization rates and costs were compared between DS and non-DS patients using regression models, adjusting for all covariates.

RESULTS

Of 711 patients, 28 (3.9%) had DS. Adjusting for all covariates, children with DS-ALL experienced substantially higher rates of ED visits (rate ratio [RR] 1.5, 95% confidence interval [95% CI]: 1.2-2.0; p = .001) and inpatient days (RR 2.5, 95% CI: 1.4-4.5; p = .002) compared to non-DS children. Outpatient visit rates were similar (RR 1.1, 95% CI: 0.9-1.3; p = .41). Among patients with available cost data (N = 533, DS = 19), median 5-year healthcare utilization cost was $247,700 among DS patients (interquartile range [IQR]: 200,900-354,500) and $196,200 among non-DS patients (IQR: 148,900-280,300; p = .02). In adjusted analyses, DS-associated costs were 50% higher (RR 1.5, 95% CI: 1.2-1.9; p < .002).

CONCLUSIONS

Healthcare utilization and treatment costs of DS-ALL patients are substantially higher than those of non-DS-ALL. Our data provide a baseline for future DS-specific cost-effectiveness studies.

A phase I study of inotuzumab ozogamicin as a single agent in pediatric patients in Japan with relapsed/refractory CD22-positive acute lymphoblastic leukemia (INO-Ped-ALL-1)

Inotuzumab ozogamicin (InO) is a CD22-directed antibody conjugated with calicheamicin approved for adult relapsed or refractory CD22-positive acute lymphoblastic leukemia (ALL). This phase 1 study primarily aimed to determine the pediatric recommended doses of InO through the standard 3 + 3 design, and to evaluate the safety, tolerability, pharmacokinetic (PK) profile, immunogenicity and efficacy of InO. Dose level 1 (DL1) was 1.8 mg/m² (days 1, 8, and 15: 0.8, 0.5, and 0.5 mg/m², respectively). Six of the seven registered patients were eligible [median age, 7.5 (2-17) years]. Although all six patients started DL1, only five completed the dose. No dose-limiting toxicity was observed. All patients experienced adverse events (AEs), including increased alanine aminotransferase and aspartate aminotransferase in four patients. Three patients experienced serious AEs, which were hepatic veno-occlusive disease (VOD), ALL, and fever. Five patients achieved complete remission (CR) or CR with incomplete blood cell recovery (CRi), among whom 3 (60%) were negative for minimal residual disease. PK findings were similar to those in adults. No patient had anti-drug antibodies to InO. In conclusion, InO was well tolerated in children and promoted similar antileukemic efficacy as in adults. Nonetheless, the risk for VOD requires attention.

Novel Insights into Fungal Infections Prophylaxis and Treatment in Pediatric Patients with Cancer

Invasive fungal diseases (IFDs) are a relevant cause of morbidity and mortality in children with cancer. Their correct prevention and management impact patients’ outcomes. The aim of this review is to highlight the rationale and novel insights into antifungal prophylaxis and treatment in pediatric patients with oncological and hematological diseases. The literature analysis showed that IFDs represent a minority of cases in comparison to bacterial and viral infections, but their impact might be far more serious, especially when prolonged antifungal therapy or invasive surgical treatments are required to eradicate colonization. A personalized approach is recommended since pediatric patients with cancer often present with different complications and require tailored therapy. Moreover, while the Aspergillus infection rate does not seem to increase, in the near future, new therapeutic recommendations should be required in light of new epidemiological data on Candidemia due to resistant species. Finally, further studies on CAR-T treatment and other immunotherapies are needed in patients with unique needs and the risk of complications. Definitive guidelines on IFD treatment considering the evolving epidemiology of antifungal resistance, new therapeutic approaches in pediatric cancer, novel antifungal drugs and the importance of an appropriate antifungal stewardship are urgently needed.

B-lineage antigens that are useful to substitute CD19 for minimal residual disease monitoring in B cell precursor acute lymphoblastic leukemia after CD19 targeting

BACKGROUND

The potential loss of CD19 during targeted treatment of B cell precursor acute lymphoblastic leukemia (BCP-ALL) can hamper flow cytometric minimal residual disease (MRD) monitoring. In the current study, we present expression data for antigens that are candidates for CD19 substitution: surface CD22, CD24, CD10, and intracellular (i) CD79a.

METHODS

Bone marrow samples from 519 consecutive children (below 18 y.o.) with primary BCP-ALL were studied with a focus on expression of CD19, CD10, CD22, CD24, and iCD79a. As these antigens are planned to be used as substitutions for CD19 for primary B cell gating, only total expression on the leukemic population (≥95% cells) was considered appropriate.

RESULTS

It was found that each of these antigens is totally expressed in nearly 90% of patients. For each single marker, a subgroup of patients without complete positivity presented with BCP-ALL harboring diverse cytogenetic and molecular genetic aberrations. Based on expression data, we have developed algorithm of simultaneous application of these antigens for initial B-lineage compartment gating, that is applicable for nearly all patients after CD19 targeting.

CONCLUSION

We conclude that the addition of CD22, CD24, and iCD79a to the conventional antibody panel and their application together with CD10 allow for the identification of B-lineage compartment including residual tumor blasts, for MFC-MRD searching in virtually all patients with BCP-ALL after CD19-directed treatment.

The current treatment approach to adolescents and young adults with acute lymphoblastic leukemia (AYA-ALL): challenges and considerations

INTRODUCTION

AYA-ALL differs from pediatric ALL in terms of clinical, biological, psychosocial factors and access to care and has an inferior outcome. It is now being recognized that pediatric-inspired protocols are superior to adult protocols for this cohort, but given the lack of randomized trials, several questions remain unanswered.

AREAS COVERED

In this review, we discuss how AYA-ALL is different from the pediatric ALL population, compare AYA ALL with ALL in middle and older age adults, review the studies that have enrolled the AYA cohort, summarize risk-stratified and response-adapted approaches, describe the biological subtypes, and review the novel agents/approaches under evaluation.

EXPERT OPINION

AYA-ALL is a complex and challenging disease that needs multidisciplinary and focused care. Well-designed clinical trials that focus on this cohort are needed to further improve the outcomes.

Management of Aggressive Non-Hodgkin Lymphomas in the Pediatric, Adolescent, and Young Adult Population: An Adult vs. Pediatric Perspective

Non-Hodgkin lymphoma (NHL) is a broad entity which comprises a number of different types of lymphomatous malignancies. In the pediatric and adolescent population, the type and prognosis of NHL varies by age and gender. In comparison to adults, pediatric and adolescent patients generally have better outcomes following treatment for primary NHL. However, relapsed/refractory (R/R) disease is associated with poorer outcomes in many types of NHL such as diffuse large B cell lymphoma and Burkitt lymphoma. Newer therapies have been approved in the use of primary NHL in the pediatric and adolescent population such as Rituximab and other therapies such as chimeric antigen receptor T-cell (CAR T-cell) therapy are under investigation for the treatment of R/R NHL. In this review, we feature the characteristics, diagnosis, and treatments of the most common NHLs in the pediatric and adolescent population and also highlight the differences that exist between pediatric and adult disease. We then detail the areas of treatment advances such as immunotherapy with CAR T-cells, brentuximab vedotin, and blinatumomab as well as cell cycle inhibitors and describe areas where further research is needed. The aim of this review is to juxtapose established research regarding pediatric and adolescent NHL with recent advancements as well as highlight treatment gaps where more investigation is needed.

Direct CNS administration of rituximab and epratuzumab in a pediatric patient with relapsed refractory CNS B-cell acute lymphoblastic leukemia

Relapsed central nervous system (CNS) leukemia presents a therapeutic challenge to pediatric oncologists. Systemic monoclonal antibody therapy has shown recent promise in patients with relapsed acute lymphoblastic leukemia, however its effect on CNS disease in this population is not well established. We describe a case of multiply relapsed and refractory CNS leukemia in an adolescent patient who responded to the intra-CNS delivery of rituximab (anti-CD20) and epratuzumab (anti-CD22) therapy, demonstrating the practical use and potential efficacy of a novel route of monoclonal antibody administration in difficult-to-treat CNS leukemia.

Monoclonal antibodies: new chance in the management of B-cell acute lymphoblastic leukemia

OBJECTIVES

This review aims to see the progress of several clinically-used monoclonal antibodies in treating ALL patients and how they improved patients' outcomes.

METHODS

We searched Web of Science, Elsevier and PubMed for relevant published studies, and summarized eligible evidence on the management of newly-diagnosed and relapsed or refractory ALL with monoclonal antibodies. Ongoing trials were identified from ClinicalTrials.gov.

RESULTS

Rituximab, an anti-CD20 monoclonal antibody, prolonged patients' complete remission duration and overall survival when combined with hyper-CVAD regimen. Another anti-CD20 monoclonal antibody, Ofatumumab, was reported to have similar benefits. Blinatumomab allows endogenous CD3-positive cytotoxic T cells to target and eliminate CD19-positive blasts. FDA has approved its efficacy in patients with R/R B-ALL and eliminating minimal residual disease (MRD). It serves as a bridge to eradicate MRD before transplantation, and may also be a new choice for patients unable to undergo transplantation. An anti-CD22 monoclonal antibody named Inotuzumab Ozogamicin showed great improvement in patients' outcome, but its toxicity to liver is also worthy of our attention.

CONCLUSION

Monoclonal antibodies are proven to be a promising immunotherapeutic strategy to improve ALL patients' outcome in the long term. There's still a need for individualized treatment with effective and well-tolerated medicines.Trial registration: ClinicalTrials.gov identifier: NCT01363128.Trial registration: ClinicalTrials.gov identifier: NCT01466179.Trial registration: ClinicalTrials.gov identifier: NCT02013167.Trial registration: ClinicalTrials.gov identifier: NCT02000427.Trial registration: ClinicalTrials.gov identifier: NCT01564784.Trial registration: ClinicalTrials.gov identifier: NCT03677596.Trial registration: ClinicalTrials.gov identifier: NCT01363297.Trial registration: ClinicalTrials.gov identifier: NCT02981628.Trial registration: ClinicalTrials.gov identifier: NCT03094611.Trial registration: ClinicalTrials.gov identifier: NCT01371630.Trial registration: ClinicalTrials.gov identifier: NCT04224571.Trial registration: ClinicalTrials.gov identifier: NCT02458014.Trial registration: ClinicalTrials.gov identifier: NCT04546399.Trial registration: ClinicalTrials.gov identifier: NCT02879695.Trial registration: ClinicalTrials.gov identifier: NCT03913559.Trial registration: ClinicalTrials.gov identifier: NCT03441061.Trial registration: ClinicalTrials.gov identifier: NCT03739814.Trial registration: ClinicalTrials.gov identifier: NCT02877303.Trial registration: ClinicalTrials.gov identifier: NCT03698552.Trial registration: ClinicalTrials.gov identifier: NCT04601584.Trial registration: ClinicalTrials.gov identifier: NCT04684147.Trial registration: ClinicalTrials.gov identifier: NCT04681105.

Recent Advances in Treatment Options for Childhood Acute Lymphoblastic Leukemia

Simple Summary

Acute lymphoblastic leukemia is the most common blood cancer in pediatric patients. Despite the enormous progress in ALL treatment, which is reflected by a high 5-year overall survival rate that reaches up to 96% in the most recent studies, there are still patients that cannot be saved. Treatment of ALL is based on conventional methods, including chemotherapy and radiotherapy. These methods carry with them the risk of very high toxicities. Severe complications related to conventional therapies decrease their effectiveness and can sometimes lead to death. Therefore, currently, numerous studies are being carried out on novel forms of treatment. In this work, classical methods of treatment have been summarized. Furthermore, novel treatment methods and the possibility of combining them with chemotherapy have been incorporated into the present work. Targeted treatment, CAR-T-cell therapy, and immunotherapy for ALL have been described. Treatment options for the relapse/chemoresistance ALL have been presented.

Abstract

Acute lymphoblastic leukemia is the most common blood cancer in pediatric patients. There has been enormous progress in ALL treatment in recent years, which is reflected by the increase in the 5-year OS from 57% in the 1970s to up to 96% in the most recent studies. ALL treatment is based primarily on conventional methods, which include chemotherapy and radiotherapy. Their main weakness is severe toxicity, which prompts dose reduction, decreases the effectiveness of the treatment, and, in some cases, can lead to death. Currently, numerous modifications in treatment regimens are applied in order to limit toxicities emerging from conventional approaches and improve outcomes. Hematological treatment of pediatric patients is reaching for more novel treatment options, such as targeted treatment, CAR-T-cells therapy, and immunotherapy. These methods are currently used in conjunction with chemotherapy. Nevertheless, the swift progress in their development and increasing efficacity can lead to applying those novel therapies as standalone therapeutic options for pediatric ALL.

Updates in the Management of Relapsed and Refractory Acute Lymphoblastic Leukemia: An Urgent Plea for New Treatments Is Being Answered!

The treatment of acute lymphoblastic leukemia (ALL) has dramatically changed over the past three decades. However, relapsed and/or refractory ALL still remains with a very low survival and high morbidity associated with its treatment. Here, we will review the outstanding progress that has been made in the treatment of relapsed and/or refractory ALL and discuss future directions and challenges that require further investigation.

Treatment of Sinusoidal Obstruction Syndrome With Defibrotide in Pediatric Cancer Patients Following Nontransplant-associated Chemotherapy: A Case Report and Review of the Literature

Sinusoidal obstruction syndrome (SOS), formerly veno-occlusive disease (VOD), in pediatric cancer patients often presents as a complication of hematopoietic stem cell transplantation, and less commonly secondary to nontransplant-associated chemotherapy. Therapy with defibrotide is well-described as standard care for transplant-associated SOS/VOD, but the treatment of nontransplant-associated SOS/VOD is less clear. We report a 3-year-old with relapsed Wilms tumor and recurrent SOS/VOD, with successful use of defibrotide during chemotherapy. A review of pediatric cancer patients with nontransplant-associated SOS/VOD treated with defibrotide revealed 83 patients, and 66 were in remission. This review supports early treatment with defibrotide in patients with nontransplant-associated SOS/VOD.

Temporal changes in incidence of relapse and outcome after relapse of childhood acute lymphoblastic leukemia over three decades; a Nordic population-based cohort study

Relapse remains the main obstacle to curing childhood acute lymphoblastic leukemia (ALL). The aims of this study were to compare incidence of relapse, prognostic factors, and survival after relapse between three consecutive Nordic Society of Pediatric Hematology and Oncology trials. Relapse occurred as a primary event in 638 of 4 458 children (1.0-14.9 years) diagnosed with Ph-negative ALL between 1992 and 2018. The 5-year cumulative incidence of relapse was 17.3% (95% CI 15.4-19.2%) and 16.5% (95% CI 14.3-18.8%) for patients in the ALL1992 and ALL2000 trials, respectively, but decreased to 8.4% (95% CI 7.0-10.1%) for patients in the ALL2008 trial. No changes in duration of first complete remission and site of relapse were observed over time; however, high hyperdiploidy, and t(12;21) decreased in the ALL2008 trial. The 4-year overall survival after relapse was 56.6% (95% CI 52.5-60.5%) and no statistically significant temporal improvements were observed. Age ≥10 years, T-cell immunophenotype, bone-marrow involvement, early and very early relapse, hypodiploidy, and Down syndrome all independently predicted worse outcome after relapse. Improvements in the primary treatment of childhood ALL has resulted in fewer relapses. However, failure to improve outcome of remaining relapses suggests a selection of harder-to-cure relapses and calls for new therapeutic strategies.

Phase II Trial of Inotuzumab Ozogamicin in Children and Adolescents With Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia: Children's Oncology Group Protocol AALL1621

PURPOSE

Children's Oncology Group trial AALL1621 was conducted to prospectively determine the safety and efficacy of inotuzumab ozogamicin (InO) in pediatric and adolescent patients with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL).

PATIENTS AND METHODS

This single-arm phase II trial enrolled patients age 1-21 years with R/R CD22-positive B-ALL. In cycle 1, InO dosing was 0.8 mg/m2 intravenously on day 1 and 0.5 mg/m2 on days 8 and 15 of a 28-day cycle with response evaluation at day 28. Using a two-stage design, the trial was continuously monitored for dose-limiting toxicities and sinusoidal obstruction syndrome (SOS). CD22 expression was retrospectively evaluated by central flow cytometry.

RESULTS

Forty-eight patients were evaluable for response and toxicity; 19 had complete response (CR) and nine CR with incomplete count recovery (CRi) after cycle 1 (CR/CRi rate: 58.3%; two-sided 90% CI, 46.5 to 69.3). Twenty-seven of 28 patients with CR or CRi had minimal residual disease measured by flow cytometry; 18 (66.7%) had minimal residual disease < 0.01%. Seven of 28 patients (25%) with CR or CRi had delayed count recovery past day 42 in cycle 1. Three (6.3%) patients had grade 3 ALT elevation and one patient had grade 3 hyperbilirubinemia in cycle 1. Of 21 patients undergoing hematopoietic stem-cell transplantation after InO, 6 (28.6%) developed grade 3 SOS. Partial CD22 expression and lower CD22 site density were associated with lower likelihood of response to InO.

CONCLUSION

InO is effective and well tolerated in heavily pretreated children and adolescents with R/R CD22-positive B-ALL. SOS after hematopoietic stem-cell transplantation and prolonged cytopenias were notable. CD22 modulation was identified as a mechanism of resistance. Expanded study of InO combined with chemotherapy is underway.

Resistance Mechanisms in Pediatric B-Cell Acute Lymphoblastic Leukemia

Despite the rapid development of medicine, even nowadays, acute lymphoblastic leukemia (ALL) is still a problem for pediatric clinicians. Modern medicine has reached a limit of curability even though the recovery rate exceeds 90%. Relapse occurs in around 20% of treated patients and, regrettably, 10% of diagnosed ALL patients are still incurable. In this article, we would like to focus on the treatment resistance and disease relapse of patients with B-cell leukemia in the context of prognostic factors of ALL. We demonstrate the mechanisms of the resistance to steroid therapy and Tyrosine Kinase Inhibitors and assess the impact of genetic factors on the treatment resistance, especially TCF3::HLF translocation. We compare therapeutic protocols and decipher how cancer cells become resistant to innovative treatments—including CAR-T-cell therapies and monoclonal antibodies. The comparisons made in our article help to bring closer the main factors of resistance in hematologic malignancies in the context of ALL.

Successful Salvage of Very Early Relapse in Pediatric Acute Lymphoblastic Leukemia With Inotuzumab Ozogamicin and HLA-haploidentical Peripheral Blood Stem Cell Transplantation With Posttransplant Cyclophosphamide

Herein, we describe a 14-year-old female patient with B-cell precursor acute lymphoblastic leukemia who relapsed in early consolidation. Minimal residual disease-negative complete remission was obtained after 1 cycle of inotuzumab ozogamicin therapy. She underwent HLA-haploidentical peripheral blood stem cell transplantation after a myeloablative conditioning regimen. Posttransplant cyclophosphamide, tacrolimus, and mycophenolate mofetil were administered for the prophylaxis of graft-versus-host disease. At 23 months, she was in complete remission. Although the administration of inotuzumab ozogamicin followed by haploidentical peripheral blood stem cell transplantation with posttransplant cyclophosphamide has been limited in children, this strategy may be an effective treatment for pediatric refractory acute lymphoblastic leukemia.

Targeted inhibitors and antibody immunotherapies: Novel therapies for paediatric leukaemia and lymphoma

Despite improved outcomes achieved in the last decades for children with newly diagnosed leukaemia and lymphoma, treatment of patients with refractory/relapsed disease remains a challenge. The cure rate is still unsatisfactory and often achieved at the cost of significant morbidity. Exploring treatment with novel agents should offer less toxic therapeutic options, without compromising efficacy. Bispecific and antibody-drug conjugates targeting CD19 and CD22 (blinatumomab and inotuzumab ozogamicin) play an important role in the treatment of relapsed and refractory B-cell precursor acute lymphoblastic leukaemia (BCP-ALL); antibodies targeting CD123 and CD38 are also under investigation for acute myeloid leukaemia (AML) and T-ALL, respectively. Targeted therapy with small molecules is of primary importance for specific genetic subtypes, such as BCR-ABL-positive ALL, FLT3-ITD AML and anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma. KMT2A-directed targeted therapy with menin inhibitors holds promise to be of relevance in KMT2A-rearranged leukaemias, known to have dismal prognosis. Target inhibition in cellular pathways such as BCL-2, RAS, MEK, Bruton's tyrosine kinase, JAK-STAT or CDK4/CDK6 inhibition may be suitable for different diseases with common mutated pathways. Nevertheless, development and approval of new agents for paediatric cancers lags behind adult therapeutic options. New regulations were implemented to accelerate drug development for children. Considering the number of oncology medicinal products available for adults and the rarity of paediatric cancers, prioritisation based on scientific evidence and medical need, as well as international collaboration, is critical. Herein, we review the current status of drug development for children with leukaemia and lymphoma, excluding cellular therapy despite its well-known significance.

Immunotherapy Associated Neurotoxicity in Pediatric Oncology

Novel immunotherapies are increasingly being employed in pediatric oncology, both in the upfront and relapsed/refractory settings. Through various mechanisms of action, engagement and activation of the immune system can cause both generalized and disease site-specific inflammation, leading to immune-related adverse events (irAEs). One of the most worrisome irAEs is that of neurotoxicity. This can present as a large spectrum of neurological toxicities, including confusion, aphasia, neuropathies, seizures, and/or death, with variable onset and severity. Earlier identification and treatment, generally with corticosteroids, remains the mainstay of neurotoxicity management to optimize patient outcomes. The pathophysiology of neurotoxicity varies across the different therapeutic strategies and remains to be elucidated in most cases. Furthermore, little is known about long-term neurologic sequelae. This review will focus on neurotoxicity seen with the most common immunotherapies used in pediatric oncology, including CAR T cell therapy, alternative forms of adoptive cell therapy, antibody therapies, immune checkpoint inhibitors, and tumor vaccines. Herein we will discuss the incidence, pathophysiology, symptomatology, diagnosis, and management strategies currently being utilized for immunotherapy-associated neurotoxicity with a focus on pediatric specific considerations.

Bispecific Antibodies and Other Non-CAR Targeted Therapies and HSCT: Decreased Toxicity for Better Transplant Outcome in Paediatric ALL?

This review will address the place of innovative, non-chemotherapy, non-CAR-T targeted therapies in the treatment of Acute Lymphoblastic Leukaemia (ALL), focusing on their use in the hematopoietic stem cell transplant (HSCT) context. The focus will be on the agent with the most experience to date, namely the bispecific T-cell engater (BiTE) blinatumomab, but references to antibody-drug conjugates (ADCs) such as inotuzumab ozogamicin and monoclonal antibodies such as daratumamab will be made as well. Specific issues to be addressed include: (1) The use of these agents to reduce measurable residual disease (MRD) prior to HSCT and their potential for improved transplant outcomes due to reduced toxicity compared to traditional chemotherapy salvage, as well as potentially increased toxicity with HSCT with particular agents; (2) the appropriate sequencing of innovative therapies, i.e., when to use BiTEs or antibodies versus CARs pre- and/or post-HSCT; this will include also the potential for impact on response of one group of agents on response to the other; (3) the role of these agents particularly in the post-HSCT relapse setting, or as maintenance to prevent relapse in this setting; (4) special populations in which these agents may substitute for traditional chemotherapy during induction or consolidation in patients with predisposing factors for toxicity with traditional therapy (e.g., Trisomy 21, infants), or those who develop infectious complications precluding delivery of full standard-of-care (SOC) chemotherapy during induction/consolidation (e.g., fungal infections); (5) the evidence we have to date regarding the potential for substitution of blinatumomab for some of the standard chemotherapy agents used pre-HSCT in patients without the above risk factors for toxicity, but with high risk disease going into transplant, in an attempt to decrease current rates of transplant-related mortality as well as morbidity; (6) the unique toxicity profile of these agents and concerns regarding particular side effects in the HSCT context. The manuscript will include both the data we have to date regarding the above issues, ongoing studies that are trying to explore them, and suggestions for future studies to further refine our knowledge base.

Insights into Modern Therapeutic Approaches in Pediatric Acute Leukemias

Pediatric cancers predominantly constitute lymphomas and leukemias. Recently, our knowledge and awareness about genetic diversities, and their consequences in these diseases, have greatly expanded. Modern solutions are focused on mobilizing and impacting a patient’s immune system. Strategies to stimulate the immune system, to prime an antitumor response, are of intense interest. Amid those types of therapies are chimeric antigen receptor T (CAR-T) cells, bispecific antibodies, and antibody–drug conjugates (ADC), which have already been approved in the treatment of acute lymphoblastic leukemia (ALL)/acute myeloid leukemia (AML). In addition, immune checkpoint inhibitors (ICIs), the pattern recognition receptors (PRRs), i.e., NOD-like receptors (NLRs), Toll-like receptors (TLRs), and several kinds of therapy antibodies are well on their way to showing significant benefits for patients with these diseases. This review summarizes the current knowledge of modern methods used in selected pediatric malignancies and presents therapies that may hold promise for the future.

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.

Acute Lymphoblastic Leukaemia in the Youngest: Haematopoietic Stem Cell Transplantation and Beyond

The ALL SCTped 2012 FORUM (For Omitting Radiation Under Majority age) trial compared outcomes for children ≥4 years of age transplanted for acute lymphoblastic leukaemia (ALL) who were randomised to myeloablation with a total body irradiation (TBI)-based or chemotherapy-based conditioning regimen. The TBI-based preparation was associated with a lower rate of relapse compared with chemoconditioning. Nevertheless, the age considered suitable for TBI was progressively raised over time to spare the most fragile youngest patients from irradiation-related complications. The best approach to use for children <4 years of age remains unclear. Children diagnosed with ALL in their first year of life, defined as infants, have a remarkably poorer prognosis compared with older children. This is largely explained by the biology of their ALL, with infants often carrying a KMT2A gene rearrangement, as well as by their fragility. In contrast, the clinical presentations and biological features of ALL in children >1 year but <4 years often resemble those presented by older children. In this review, we explore the state of the art regarding haematopoietic stem cell transplantation (HSCT) in children <4 years, the preparative regimens available, and new developments in the field that may influence treatment decisions.

Allogeneic Hematopoietic Stem Cell Transplantation for Children With Acute Lymphoblastic Leukemia: Shifting Indications in the Era of Immunotherapy

Pediatric acute lymphoblastic leukemia generally carries a good prognosis, and most children will be cured and become long-term survivors. However, a portion of children will harbor high-risk features at the time of diagnosis, have a poor response to upfront therapy, or suffer relapse necessitating more intensive therapy, which may include allogeneic hematopoietic stem cell transplant (HSCT). Recent advances in risk stratification, improved detection and incorporation of minimal residual disease (MRD), and intensification of upfront treatment have changed the indications for HSCT over time. For children in first complete remission, HSCT is generally reserved for those with the highest risk of relapse. These include patients with unfavorable features/cytogenetics who also have a poor response to induction and consolidation chemotherapy, usually reflected by residual blasts after prednisone or by detectable MRD at pre-defined time points. In the relapsed setting, children with first relapse of B-cell ALL are further stratified for HSCT depending on the time and site of relapse, while all patients with T-cell ALL are generally consolidated with HSCT. Alternatives to HSCT have also emerged over the last decade including immunotherapy and chimeric antigen receptor (CAR) T-cell therapy. These novel agents may spare toxicity while attempting to achieve MRD-negative remission in the most refractory cases and serve as a bridge to HSCT. In some situations, these emerging therapies can indeed be curative for some children with relapsed or resistant disease, thus, obviating the need for HSCT. In this review, we seek to summarize the role of HSCT in the current era of immunotherapy.

Near-Haploidy and Low-Hypodiploidy in B-Cell Acute Lymphoblastic Leukemia: When Less Is Too Much

Hypodiploidy with less than 40 chromosomes is a rare genetic abnormality in B-cell acute lymphoblastic leukemia (B-ALL). This condition can be classified based on modal chromosome number as low-hypodiploidy (30–39 chromosomes) and near-haploidy (24–29 chromosomes), with unique cytogenetic and mutational landscapes. Hypodiploid B-ALL with <40 chromosomes has an extremely poor outcome, with 5-year overall survival rates below 50% and 20% in childhood and adult B-ALL, respectively. Accordingly, this genetic feature represents an adverse prognostic factor in B-ALL and is associated with early relapse and therapy refractoriness. Notably, half of all patients with hypodiploid B-ALL with <40 chromosomes cases ultimately exhibit chromosome doubling of the hypodiploid clone, resulting in clones with 50–78 chromosomes. Doubled clones are often the major clones at diagnosis, leading to “masked hypodiploidy”, which is clinically challenging as patients can be erroneously classified as hyperdiploid B-ALL. Here, we summarize the main cytogenetic and molecular features of hypodiploid B-ALL subtypes, and provide a brief overview of the diagnostic methods, standard-of-care treatments and overall clinical outcome. Finally, we discuss molecular mechanisms that may underlie the origin and leukemogenic impact of hypodiploidy and may open new therapeutic avenues to improve survival rates in these patients.