Outcomes for Australian children with relapsed/refractory acute lymphoblastic leukaemia treated with blinatumomab

Incidence of CD19-negative relapse after CD19-targeted immunotherapy in R/R BCP acute lymphoblastic leukemia: a review

There are inconsistencies in the reporting of CD19 antigen status following treatment with CD19-targeted therapies. A majority of evidence comes from studies reporting small sample sizes. In this review, we systematically summarize published studies that have reported rates of CD19-negative relapse after treatment with either blinatumomab or CD19-directed CAR T-cell therapy and report the rates of CD19-negative relapse when evaluated in a standardized way across trials. CD19-negative relapse appears to occur more commonly in relapses following CAR T-cell therapy compared with blinatumomab, whether proportions are calculated among all treated patients (8.7% vs 4.5%) or among patients who relapse (30% vs 22.5%). The median (range) duration of follow-up was 29.3 (17.4-50.8) and 20.4 (6.9-49.0) months for publications on blinatumomab (n = 10) and CAR T-cell therapies (n = 23), respectively. There is a need for standardized reporting of CD19 antigen status in the setting of relapse following novel immunotherapies to inform clinical practice.

Acute Lymphoblastic Leukemia Immunotherapy Treatment: Now, Next, and Beyond

Acute lymphoblastic leukemia (ALL) is a blood cancer that primarily affects children but also adults. It is due to the malignant proliferation of lymphoid precursor cells that invade the bone marrow and can spread to extramedullary sites. ALL is divided into B cell (85%) and T cell lineages (10 to 15%); rare cases are associated with the natural killer (NK) cell lineage (<1%). To date, the survival rate in children with ALL is excellent while in adults continues to be poor. Despite the therapeutic progress, there are subsets of patients that still have high relapse rates after chemotherapy or hematopoietic stem cell transplantation (HSCT) and an unsatisfactory cure rate. Hence, the identification of more effective and safer therapy choices represents a primary issue. In this review, we will discuss novel therapeutic options including bispecific antibodies, antibody-drug conjugates, chimeric antigen receptor (CAR)-based therapies, and other promising treatments for both pediatric and adult patients.

[Safety and short-term effectiveness of blinatumomab in the treatment of childhood relapsed/refractory acute lymphoblastic leukemia]

OBJECTIVES

To study the safety and short-term effectiveness of blinatumomab in the treatment of childhood relapsed/refractory acute lymphoblastic leukemia (R/R-ALL).

METHODS

Six children with R/R-ALL who received blinatumomab treatment from August 2021 to August 2022 were included as subjects, and a retrospective analysis was performed for their clinical data.

RESULTS

Among the six children, there were three boys and three girls, with a median age of 10.5 (5.0-13.0) years at the time of inclusion. Of all six children, one had refractory ALL and did not achieve remission after several times of chemotherapy, and 5 relapsed for the first time, with a median time of 30 (9-60) months from diagnosis to relapse. Minimal residual disease (MRD) before treatment was 15.50% (0.08%-78.30%). Three children achieved complete remission after treatment, among whom two had negative conversion of MRD. Five children had cytokine release syndrome (CRS), among whom 3 had grade 1 CRS and 2 had grade 2 CRS. Four children were bridged to allogeneic hematopoietic stem cell transplantation, with a median interval of 50 (40-70) days from blinatumomab treatment to transplantation. The six children were followed up for a median time of 170 days, and the results showed an overall survival rate of 41.7% (95%CI: 5.6%-76.7%) and a median survival time of 126 (95%CI: 53-199) days.

CONCLUSIONS

Blinatumomab has good short-term safety and effectiveness in the treatment of childhood R/R-ALL, and its long-term effectiveness needs to be confirmed by studies with a larger sample size.

Efficacy and Safety of Blinatumomab for the Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia: A Systemic Review and Meta-Analysis

OBJECTIVE

The aim was to evaluate the efficacy and safety of blinatumomab monotherapy for the treatment of relapsed/refractory acute lymphoblastic leukemia (R/R B-ALL).

METHODS

PubMed, Embase, Web of Science, and Cochrane Library were searched to collect clinical studies related to blinatumomab. The primary outcome measures were complete remission (CR), and minimal residual disease (MRD) response. Prognostic indicators included overall survival (OS) and relapse-free survival time (RFS). Grade ≥3 adverse reactions were mainly analyzed for safety, including cytokine release syndrome (CRS), neurological events and hematological toxicity. The heterogeneity was quantified by I² statistic, which reflected the proportion of the true heterogeneity to the variance of the total effect size. Studies were considered heterogeneous if the I² statistic was greater than 50%, and conversely, studies were homogeneous.

RESULTS

A total of 18 studies involving 1,373 patients were included. The analysis results showed a CR rate of 54% (95%CI:44%-64%) and an MRD response rate of 43% (95%CI:34%-51%). The CR rate was higher in patients with bone marrow (BM) blast <50% than in patients with BM blast ≥50% (71% vs. 34%). The median OS and RFS were 8.16 months (95%CI:6.64-9.69) and 6.02 months (95%CI:4.63-7.41), respectively. For safety analysis, the incidence of grade ≥3 adverse events (AEs) was 80% (95%CI:72%-88%), the incidence of grade ≥3 neurological toxicity was 7% (95%CI:4%-11%), and the incidence of grade ≥3 CRS was 3% (95%CI:2%-5%). However, the mixture of retrospective and prospective studies led to heterogeneity to some extent in this meta-analysis.

CONCLUSION

Blinatumomab is effective in the treatment of R/R B-ALL with a controlled occurrence of AEs and a reliable safety profile.

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.

Super-refractory status epilepticus during blinatumomab initiation for B-cell acute lymphoblastic leukemia

Seizures have been reported as an adverse effect of blinatumomab, a bispecific T-cell engager monoclonal antibody, which is mainly used for the treatment of pediatric relapsed/refractory leukemia. Here, we present the first reported case of super-refractory status epilepticus in an 11-year-old boy with B-cell acute lymphoblastic leukemia (B-ALL) while receiving blinatumomab. Our patient had a complete return to baseline despite enduring encephalopathy, refractory subclinical seizures requiring prolonged therapeutic burst suppression and MRI signal changes. This case demonstrates that super-refractory status epilepticus is a possible neurotoxic adverse effect of blinatumomab treatment, which responds well to conventional protocols for acute refractory seizures.

Blinatumomab as bridging therapy in paediatric B-cell acute lymphoblastic leukaemia complicated by invasive fungal disease

Invasive fungal disease (IFD) remains a challenging complication of treatment for paediatric acute leukaemia. Consensus fungal treatment guidelines recommend withholding chemotherapy to facilitate immune recovery in this setting, yet prolonged delays in leukaemia therapy increase risk of relapse. Blinatumomab, a bispecific T‐cell engager targeting cells expressing CD19, has shown promise for treatment of relapsed/refractory B‐cell acute lymphoblastic leukaemia (B‐ALL) and is associated with reduced toxicity compared to conventional chemotherapy. With close monitoring of minimal residual disease, we demonstrate that children with B‐ALL can receive repeated cycles of bridging blinatumomab whilst conventional chemotherapy is withheld during treatment and recovery from IFD.

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.

Correlation between a 10-color flow cytometric measurable residual disease (MRD) analysis and molecular MRD in adult B-acute lymphoblastic leukemia

BACKGROUND

Measurable residual disease (MRD) monitoring in acute lymphoblastic leukemia (ALL) is an important predictive factor for patient outcome and treatment intensification. Molecular monitoring, particularly with quantitative polymerase chain reaction (qPCR) to measure immunoglobin heavy or kappa chain (Ig) or T-cell receptor (TCR) gene rearrangements, offers high sensitivity but accessibility is limited by expertise, cost, and turnaround time. Flow cytometric assays are cheaper and more widely available, and sensitivity is improved with multi-parameter flow cytometry at eight or more colors.

METHODS

We developed a 10-color single tube flow cytometry assay. Samples were subject to bulk ammonium chloride lysis to maximize cell yields with a target of 1 × 10⁶ events. Once normal maturation patterns were established, patient samples were analyzed in parallel to standard molecular monitoring.

RESULTS

Flow cytometry was performed on 114 samples. An informative immunophenotype was identifiable in all 22 patients who had a diagnostic sample. MRD analysis was performed on 87 samples. The median lower limits of detection and quantification were 0.004% (range 0.0005%-0.028%) and 0.01% (range 0.001%-0.07%) respectively. Sixty-five samples had concurrent molecular MRD testing, with good correlation (r = 0.83, p < 0.001). Results were concordant in 52 samples, and discordant in 13 samples, including one case where impending relapse was detected by flow cytometry but not Ig/TCR qPCR.

CONCLUSIONS

Our 10-color flow cytometric MRD assay provided adequate sensitivity and good correlation with molecular assays. This technique offers rapid and affordable testing in B-ALL patients, including cases where a suitable molecular assay cannot be developed or has reduced sensitivity.

Blinatumomab in Children and Adolescents with Relapsed/Refractory B Cell Precursor Acute Lymphoblastic Leukemia: A Real-Life Multicenter Retrospective Study in Seven AIEOP (Associazione Italiana di Ematologia e Oncologia Pediatrica) Centers

Five-year event-free survival in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) currently exceeds 80-85%. However, 15-20% of patients still experience a relapsed/refractory disease. From 1 January 2015 to 31 December 2020, thirty-nine patients, 0-21 years old with r/r BCP-ALL were treated with blinatumomab with the aim of inducing remission (n = 13) or reducing MRD levels (n = 26) in the frame of different multiagent chemotherapy schedules, in seven AIEOP centers. Patients were treated in compassionate and/or off-label settings and were not enrolled in any controlled clinical trials. Treatment was well tolerated; 22 (56.4%) patients reported adverse events (AE) on a total of 46 events registered, of which 27 (58.7%) were ≤2 grade according to CTCAE. Neurological AEs were 18 (39.1%); only two patients required transient blinatumomab discontinuation. Complete remission (CR) rate was 46% for the 13 patients treated with ≥5% blasts and 81% PCR/FC MRD negativity in the 26 patients with blasts < 5%. Median relapse-free survival was 33.4 months (95% CI; 7.5-59.3); median overall survival was not reached over a mean follow-up of 16 months. In our study, as in other real-life experiences, blinatumomab proved to be effective and well-tolerated, able to induce a high rate of CR and MRD negativity.

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.

Secondary Dysgammaglobulinemia in Children with Hematological Malignancies Treated with Targeted Therapies

Targeted therapies have emerged as innovative treatments for patients whose disease does not respond to conventional chemotherapy, and their use has widely expanded in the field of pediatric hematologic malignancies in the last decade. While they carry the promise of improved disease control and survival and are currently investigated in first-line treatment protocols for patients with poor prognostic markers, they are associated with a considerable incidence of specific toxicities, including cytokine-release syndrome, neurotoxicity, hepatotoxicity, nephrotoxicity, cardiotoxicity, endocrine adverse events, and infectious complications. Iatrogenic or secondary dysgammaglobulinemia is a main consequence of targeted therapies using monoclonal antibodies and other antibody-derived treatments that target specific antigens on lymphoid cells (blinatumomab, inotuzumab ozogamicin, rituximab), chimeric antigen receptor T cells, tyrosine kinase inhibitors (imatinib, dasatinib, nilotinib) and, to a lesser extent, checkpoint inhibitors (pembrolizumab, nivolumab). This review discusses the diagnosis and incidence of secondary or iatrogenic dysgammaglobulinemia in children treated with targeted therapies for leukemias and lymphomas, and options for monitoring and treatment.

Blinatumomab in Pediatric Acute Lymphoblastic Leukemia-From Salvage to First Line Therapy (A Systematic Review)

Acute lymphoblastic leukemia is by far the most common malignancy in children, and new immunotherapeutic approaches will clearly change the way we treat our patients in future years. Blinatumomab is a bispecific T-cell-engaging antibody indicated for the treatment of relapsed/refractory acute lymphoblastic leukemia (R/R-ALL). The use of blinatumomab in R/R ALL has shown promising effects, especially as a bridging tool to hematopoietic stem cell transplantation. For heavily pretreated patients, the response to one or two cycles of blinatumomab ranges from 34% to 66%. Two randomized controlled trials have very recently demonstrated an improved reduction in minimal residual disease as well as an increased survival for patients treated with blinatumomab compared to standard consolidation treatment in first relapse. Current trials using blinatumomab frontline for high-risk patients or as a consolidation treatment post-transplant will show whether efficacy is even higher in less heavily pretreated patients. Due to the distinct pattern of adverse events compared to high-dose conventional chemotherapy, blinatumomab could play an important role for patients with a risk for severe chemotherapy-associated toxicities. This systematic review discusses all published results for blinatumomab in children as well as all ongoing clinical trials.

Minimal Residual Disease Prior to and After Haematopoietic Stem Cell Transplantation in Children and Adolescents With Acute Lymphoblastic Leukaemia: What Level of Negativity Is Relevant?

Minimal residual disease (MRD) assessment plays a central role in risk stratification and treatment guidance in paediatric patients with acute lymphoblastic leukaemia (ALL). As such, MRD prior to haematopoietic stem cell transplantation (HSCT) is a major factor that is independently correlated with outcome. High burden of MRD is negatively correlated with post-transplant survival, as both the risk of leukaemia recurrence and non-relapse mortality increase with greater levels of MRD. Despite growing evidence supporting these findings, controversies still exist. In particular, it is still not clear whether multiparameter flow cytometry and real-time quantitative polymerase chain reaction, which is used to recognise immunoglobulin and T-cell receptor gene rearrangements, can be employed interchangeably. Moreover, the higher sensitivity in MRD quantification offered by next-generation sequencing techniques may further refine the ability to stratify transplant-associated risks. While MRD quantification from bone marrow prior to HSCT remains the state of the art, heavily pre-treated patients may benefit from additional staging, such as using ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography to detect focal residues of disease. Additionally, the timing of MRD detection (i.e., immediately before administration of the conditioning regimen or weeks before) is a matter of debate. Pre-transplant MRD negativity has previously been associated with superior outcomes; however, in the recent For Omitting Radiation Under Majority age (FORUM) study, pre-HSCT MRD positivity was associated with neither relapse risk nor survival. In this review, we discuss the level of MRD that may require pre-transplant therapy intensification, risking time delay and complications (as well as losing the window for HSCT if disease progression occurs), as opposed to an adapted post-transplant strategy to achieve long-term remission. Indeed, MRD monitoring may be a valuable tool to guide individualised treatment decisions, including tapering of immunosuppression, cellular therapies (such as donor lymphocyte infusions) or additional immunotherapy (such as bispecific T-cell engagers or chimeric antigen receptor T-cell therapy).