Phase I/Phase II Study of Blinatumomab in Pediatric Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia

A Pediatric Case of B Cell Precursor ALL With Blinatumomab-associated Encephalopathy

Blinatumomab is a CD3/CD19-directed bispecific T-cell engager used to treat relapsed or refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Although blinatumomab has shown efficacy, it can cause serious adverse events, including cytokine release syndrome and neurological events. Among the neurological events, encephalopathy is rare, and knowledge is lacking. Herein, we present a pediatric case of blinatumomab-associated encephalopathy that initially presented with refractory convulsions and later developed into a cerebral infarction. The patient experienced prolonged paralysis and increased brain damage.

Different Models, Same Results: Considerations When Choosing Between Approaches to Model Cost Effectiveness of Chimeric-Antigen Receptor T-Cell Therapy Versus Standard of Care

OBJECTIVE

Chimeric antigen-receptor T-cell therapy (CAR-T) is characterised by early phase data at the time of registration, high upfront cost and a complex manufacturing and administration process compared with standard therapies. Our objective was to compare the performance of different models to assess the cost effectiveness of CAR-T using a state-transition model (STM), partitioned survival model (PSM) and discrete event simulation (DES).

METHODS

Individual data for tisagenlecleucel for the treatment of young patients with acute lymphoblastic leukaemia (ALL) were used to populate the models. Costs and benefits were measured over a lifetime to generate a cost per quality-adjusted life-year (QALY). Model performance was compared quantitatively on the outcomes generated and a checklist developed summarising the components captured by each model type relevant to assessing cost effectiveness of CAR-T.

RESULTS

Models generated similar results with base-case analyses ranging from an incremental cost per QALY of $96,074-$99,625. DES was the only model to specifically capture CAR-T wait time, demonstrating a substantial loss of benefit of CAR-T with increased wait time.

CONCLUSION

Although model type did not meaningfully impact base-case results, the ability to incorporate an outcome-based payment arrangement (OBA) and wait time are important elements to consider when selecting a model for CAR-T. DES provided greater flexibility compared with STM and PSM approaches to deal with the complex manufacturing and administration process that can lead to extended wait times and substantially reduce the benefit of CAR-T. This is an important consideration when selecting a model type for CAR-T, so major drivers of uncertainty are considered in funding decisions.

Bispecific antibodies: advancing precision oncology

Bispecific antibodies (bsAbs) are engineered molecules designed to target two different epitopes or antigens. The mechanism of action is determined by the bsAb molecular targets and structure (or format), which can be manipulated to create variable and novel functionalities, including linking immune cells with tumor cells, or dual signaling pathway blockade. Several bsAbs have already changed the treatment landscape of hematological malignancies and select solid cancers. However, the mechanisms of resistance to these agents are understudied and the management of toxicities remains challenging. Herein, we review the principles in bsAb engineering, current understanding of mechanisms of action and resistance, data for clinical application, and provide a perspective on ongoing challenges and future developments in this field.

Current landscape of CD3 bispecific antibodies in hematologic malignancies

Over the past 30 years the incorporation of monoclonal antibody (mAb) treatments into the management of hematologic malignancies has led to significant improvements in patient outcomes. The key limitation of mAb treatments is the necessity for target antigen presentation on major histocompatibility complex (MHC) and costimulatory molecules to elicit a cytotoxic immune response. With the advent of bispecific antibodies (BsAbs), these limitations can be overcome through direct stimulation of cytotoxic T cells, thus limiting tumor cell evasion. BsAbs are rapidly being incorporated into treatment regimens for hematologic malignancies, and there are now seven FDA-approved treatments in this class, six of which have been approved in the past year. In this review we describe the function, complications, and clinical trial data available for CD3 BsAbs in the treatment of lymphoma, myeloma, and leukemia.

Bispecific and multispecific antibodies in oncology: opportunities and challenges

Research into bispecific antibodies, which are designed to simultaneously bind two antigens or epitopes, has advanced enormously over the past two decades. Owing to advances in protein engineering technologies and considerable preclinical research efforts, bispecific antibodies are constantly being developed and optimized to improve their efficacy and to mitigate toxicity. To date, >200 of these agents, the majority of which are bispecific immune cell engagers, are in either preclinical or clinical evaluation. In this Review, we discuss the role of bispecific antibodies in patients with cancer, including history and development, as well as innovative targeting strategies, clinical applications, and adverse events. We also discuss novel alternative bispecific antibody constructs, such as those targeting two antigens expressed by tumour cells or cells located in the tumour microenvironment. Finally, we consider future research directions in this rapidly evolving field, including innovative antibody engineering strategies, which might enable more effective delivery, overcome resistance, and thus optimize clinical outcomes.

Prospective use of molecular minimal residual disease for risk stratification in children and adolescents with acute lymphoblastic leukemia : Long-term results of the AIEOP-BFM ALL 2000 trial in Austria

Since 1979 Austrian children and adolescents with acute lymphoblastic leukemia (ALL) have been treated according to protocols of the Berlin-Frankfurt-Münster (BFM) study group. The Associazione Italiana di Ematologia e Oncologia Pediatrica and BFM (AIEOP-BFM) ALL 2000 study was designed to prospectively study patient stratification into three risk groups using minimal residual disease (MRD) on two time points during the patient's early disease course. The MRD levels were monitored by detection of clone-specific rearrangements of the immunoglobulin and T‑cell receptor genes applying a quantitative polymerase chain reaction-based technique. The 7‑year event-free survival (EFS) and overall survival rates for all 608 Austrian patients treated between June 1999 and December 2009 within the AIEOP-BFM 2000 study were 84 ± 2% and 91 ± 1%, respectively, with a median observation time of 6.58 years. Event-free survival for patients with precursor B‑cell and T‑cell ALL were 84 ± 2% (n = 521) and 84 ± 4% (n = 87; p = 0.460), respectively. The MRD assessment was feasible in 94% of the patients and allowed the definition of precursor B‑cell ALL patients with a low, intermediate or high risk of relapse even on top of clinically relevant subgroups. A similar finding with respect to MRD relevance in T‑ALL patients was not possible due to the small number of patients and events. Since this pivotal international AIEOP-BFM ALL 2000 trial, molecular response to treatment has been continuously used with additional refinements to stratify patients into different risk groups in all successive trials of the AIEOP-BFM ALL study group.

Population Pharmacokinetics of Inotuzumab Ozogamicin in Pediatric Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia: Results of Study ITCC-059

BACKGROUND AND OBJECTIVE

Inotuzumab ozogamicin is an antibody-drug conjugate approved for treating relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in adults. Pediatric pharmacokinetic data of inotuzumab ozogamicin are lacking. This study is the first to examine the population pharmacokinetics of inotuzumab ozogamicin in pediatric patients with relapsed/refractory BCP-ALL.

METHODS

From 531 adult patients with B-cell non-Hodgkin's lymphoma, 234 adult patients with BCP-ALL, and 53 pediatric patients with BCP-ALL, 8924 inotuzumab ozogamicin serum concentrations were analyzed using non-linear mixed-effects modeling. A published adult inotuzumab ozogamicin population-pharmacokinetic model, a two-compartment model with linear and time-dependent clearance, was adapted to describe the pediatric data.

RESULTS

Modifications in this analysis, compared to the published adult model, included: (i) re-estimating pharmacokinetic parameters and covariate effects; (ii) modifying covariate representation; and (iii) introducing relevant pediatric covariate effects (age on the decay coefficient of time-dependent clearance and ALL effect (disease type and/or different bioanalytical analysis methods) on initial values of time-dependent clearance). For patients with relapsed/refractory BCP-ALL, increasing age was associated with a decreasing decay coefficient of time-dependent clearance, reflecting that the target-mediated drug clearance declines more rapidly in children. In pediatric BCP-ALL, the median [interquartile range] cumulative area under the concentration-time curve was significantly higher among responders (n = 42) versus non-responders (n = 10) at the end of the first cycle (26.1 [18.9-35.0] vs 10.1 [9.19-16.1], × 103 ng*h/mL, p < 0.001). From simulations performed at the recommended pediatric phase II dose, inotuzumab ozogamicin exposure reached a similar level as observed in responding pediatric trial participants.

CONCLUSIONS

The pharmacokinetic profile of inotuzumab ozogamicin in pediatric patients with relapsed/refractory BCP-ALL was well described in this study. No dose adjustment is required clinically for pediatric patients with BCP-ALL based on the simulated inotuzumab ozogamicin exposure at the recommended pediatric phase II dose, promising efficacy and acceptable tolerability.

Reactions and adverse events induced by T-cell engagers as anti-cancer immunotherapies, a comprehensive review

T-cell engagers (TCE) are cancer immunotherapies that have recently demonstrated meaningful benefit for patients with hematological malignancies and solid tumors. The anticipated widespread use of T cell engagers poses implementation challenges and highlights the need for guidance to anticipate, mitigate, and manage adverse events. By mobilizing T-cells directly at the contact of tumor cells, TCE mount an obligatory and immediate anti-tumor immune response that could result in diverse reactions and adverse events. Cytokine release syndrome (CRS) is the most common reaction and is largely confined to the first drug administrations during step-up dosage. Cytokine release syndrome should be distinguished from infusion related reaction by clinical symptoms, timing to occurrence, pathophysiological aspects, and clinical management. Other common reactions and adverse events with TCE are immune effector Cell-Associated Neurotoxicity Syndrome (ICANS), infections, tumor flare reaction and cytopenias. The toxicity profiles of TCE and CAR-T cells have commonalities and distinctions that we sum-up in this review. As compared with CAR-T cells, TCE are responsible for less frequently severe CRS or ICANS. This review recapitulates terminology, pathophysiology, severity grading system and management of reactions and adverse events related to TCE.

Roadmap for the next generation of Children's Oncology Group rhabdomyosarcoma trials

Clinical trials conducted by the Intergroup Rhabdomyosarcoma (RMS) Study Group and the Children's Oncology Group have been pivotal to establishing current standards for diagnosis and therapy for RMS. Recent advancements in understanding the biology and clinical behavior of RMS have led to more nuanced approaches to diagnosis, risk stratification, and treatment. The complexities introduced by these advancements, coupled with the rarity of RMS, pose challenges to conducting large-scale phase 3 clinical trials to evaluate new treatment strategies for RMS. Given these challenges, systematic planning of future clinical trials in RMS is paramount to address pertinent questions regarding the therapeutic efficacy of drugs, biomarkers of response, treatment-related toxicity, and patient quality of life. Herein, the authors outline the proposed strategic approach of the Children's Oncology Group Soft Tissue Sarcoma Committee to the next generation of RMS clinical trials, focusing on five themes: improved novel agent identification and preclinical to clinical translation, more efficient trial development and implementation, expanded opportunities for knowledge generation during trials, therapeutic toxicity reduction and quality of life, and patient engagement.

Cardiotoxic profiles of CAR-T therapy and bispecific T-cell engagers in hematological cancers

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy and bispecific T-cell engagers, which redirect T-cells to tumor antigens, have immensely benefitted patients with relapsed/refractory B-cell cancers. How these therapies differ in cardiotoxicity is underexplored. We used the World Health Organization pharmacovigilance database, VigiBase, to compare cardiotoxicity profiles between CD19-targeted CAR-T therapy and blinatumomab (a CD19/CD3-targeted bispecific T-cell engager).

METHODS

Safety reports in VigiBase were filtered for diffuse large B-cell lymphoma (DLBCL, n = 17,479) and acute lymphocytic leukemia (ALL, n = 28,803) for all adverse reactions. Data were further filtered for patients taking CAR-T therapy or blinatumomab. Reporting odds ratios (ROR) and fatality rates were compared between CAR-T cell products (e.g. tisagenlecleucel and axicabtagene ciloleucel), and between CAR-T therapy and blinatumomab.

RESULTS

Tisagenlecleucel is associated with cardiac failure (IC025 = 0.366) with fatality rates of 85.7% and 80.0% in DLBCL and pediatric ALL patients respectively. For DLBCL patients, axicabtagene ciloleucel has greater reporting for hypotension than tisagenlecleucel (ROR: 2.54; 95% CI: 1.28-5.03; p = 0.012), but tisagenlecleucel has higher fatality rates for hypotension than axicabtagene ciloleucel [50.0% (tisagenlecleucel) vs 5.6% (axicabtagene ciloleucel); p < 0.001]. Blinatumomab and tisagenlecleucel have similar fatality rates for hypotension in pediatric ALL patients [34.7% (tisagenlecleucel) vs 20.0% (blinatumomab); p = 0.66].

CONCLUSIONS

Tisagenlecleucel is associated with severe and fatal adverse cardiac events, with higher fatality rates for hypotension compared to axicabtagene ciloleucel in DLBCL patients, but similar hypotension fatality rates compared to blinatumomab in pediatric ALL patients. Effective management necessitates experienced physicians, including cardio-oncologists, skilled in interdisciplinary approaches to manage these toxicities.

Low-risk relapsed acute lymphoblastic leukemia in children and young adults: what have we learnt and what's next?

While outcomes for newly diagnosed children with acute lymphoblastic leukemia (ALL) have improved over the last few decades, 10-15% will relapse. Outcomes for those children with relapse remains a challenge, with 5-year overall survival of approximately 35-60%. Large cooperative group trials have identified factors associated with favorable (low risk, LR) outcome at relapse, including later relapse, B-cell phenotype, isolated extramedullary relapse and a good response to initial re-induction therapy. Contemporary therapeutic regimens are aimed at improving outcomes, while decreasing toxicity. A main focus of current research involves how immunotherapy can be best incorporated with cytotoxic chemotherapy to improve survival in relapsed ALL. Here we review therapeutic strategies for LR relapse, including review of recently completed and ongoing trials.

Bispecific T-cell engagers in childhood B-acute lymphoblastic leukemia

Immunotherapy has revolutionized treatment for a wide variety of cancers yet its use has been relatively limited in childhood malignancies. With the introduction of bispecific T-cell engagers (BiTE®) and chimeric antigen T-cell receptor technologies, previously refractory patients have attained remission, including molecularly negative states of disease, thus providing the possibility of long-term cure. Blinatumomab is a widely available CD3-CD19 BiTE that has dramatically changed the landscape of therapy for some children with precursor-B acute lymphoblastic leukemias (B-ALL) and lymphoblastic lymphomas. Challenges remain with using BiTE in a broader population although the appeal of now-confirmed reduced toxicity and deeper molecular remissions suggests that this approach will be an essential part of future treatment of childhood B-ALL. Herein, we review some of the pertinent literature covering clinical trials with blinatumomab and address future approaches and combination trials including BiTE.

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.

Small-molecule-mediated control of the anti-tumour activity and off-tumour toxicity of a supramolecular bispecific T cell engager

The broader clinical use of bispecific T cell engagers for inducing anti-tumour toxicity is hindered by their on-target off-tumour toxicity and the associated neurotoxicity and cytokine-release syndrome. Here we show that the off-tumour toxicity of a supramolecular bispecific T cell engager binding to the T cell co-receptor CD3 and to the human epidermal growth factor receptor 2 on breast tumour cells can be halted by disengaging the T cells from the tumour cells via the infusion of the small-molecule drug amantadine, which disassembles the supramolecular aggregate. In mice bearing human epidermal growth factor receptor 2-expressing tumours and with a human immune system, high intravenous doses of such a 'switchable T cell nanoengager' elicited strong tumour-specific adaptive immune responses that prevented tumour relapse, while the infusion of amantadine restricted off-tumour toxicity, cytokine-release syndrome and neurotoxicity. Supramolecular chemistry may be further leveraged to control the anti-tumour activity and off-tumour toxicity of bispecific antibodies.

A Phase I Study of Acapatamab, a Half-life Extended, PSMA-Targeting Bispecific T-cell Engager for Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Safety and efficacy of acapatamab, a prostate-specific membrane antigen (PSMA) x CD3 bispecific T-cell engager were evaluated in a first-in-human study in metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

Patients with mCRPC refractory to androgen receptor pathway inhibitor therapy and taxane-based chemotherapy received target acapatamab doses ranging from 0.003 to 0.9 mg in dose exploration (seven dose levels) and 0.3 mg (recommended phase II dose) in dose expansion intravenously every 2 weeks. Safety (primary objective), pharmacokinetics, and antitumor activity (secondary objectives) were assessed.

RESULTS

In all, 133 patients (dose exploration, n = 77; dose expansion, n = 56) received acapatamab. Cytokine release syndrome (CRS) was the most common treatment-emergent adverse event seen in 97.4% and 98.2% of patients in dose exploration and dose expansion, respectively; grade ≥ 3 was seen in 23.4% and 16.1%, respectively. Most CRS events were seen in treatment cycle 1; incidence and severity decreased at/beyond cycle 2. In dose expansion, confirmed prostate-specific antigen (PSA) responses (PSA50) were seen in 30.4% of patients and radiographic partial responses in 7.4% (Response Evaluation Criteria in Solid Tumors 1.1). Median PSA progression-free survival (PFS) was 3.3 months [95% confidence interval (CI): 3.0-4.9], radiographic PFS per Prostate Cancer Clinical Trials Working Group 3 was 3.7 months (95% CI: 2.0-5.4). Acapatamab induced T-cell activation and increased cytokine production several-fold within 24 hours of initiation. Treatment-emergent antidrug antibodies were detected in 55% and impacted serum exposures in 36% of patients in dose expansion.

CONCLUSIONS

Acapatamab was safe and tolerated and had a manageable CRS profile. Preliminary signs of efficacy with limited durable antitumor activity were observed. Acapatamab demonstrated pharmacokinetic and pharmacodynamic activity.

Discrete Event Simulation to Incorporate Infusion Wait-Time When Assessing Cost-Effectiveness of a Chimeric-Antigen Receptor T Cell Therapy

OBJECTIVES

The main objective was to use discrete event simulation to model the impact of wait-time, defined as the time between leukapheresis and chimeric antigen receptor (CAR-T) infusion, when assessing the cost-effectiveness of tisagenlecleucel in young patients with relapsed/refractory acute lymphoblastic leukemia.

METHODS

The movement of patients through the model was determined by parametric time-to-event distributions, with the competing risk of an event determining the costs and quality-adjusted life-years (QALYs) assigned. Cost-effectiveness was expressed using the incremental cost-effectiveness ratio (ICER) for tisagenlecleucel compared with chemotherapy over the lifetime.

RESULTS

The base case generated a total of 5.79 QALYs and $622 872 for tisagenlecleucel and 1.19 QALYs and $181 219 for blinatumomab, resulting in an ICER of $96 074 per QALY. An increase in mean CAR-T wait-time to 6.20 months reduced the benefit and costs of tisagenlecleucel to 2.78 QALYs and $294 478 because of fewer patients proceeding to infusion, reducing the ICER to $71 112 per QALY. Alternatively, when the cost of tisagenlecleucel was assigned pre-infusion in sensitivity analysis, the ICER increased with increasing wait-time.

CONCLUSIONS

Under a payment arrangement where CAR-T cost is incurred post-infusion, the loss of benefit to patients is not reflected in the ICER. This may be misguiding to decision makers, where cost-effectiveness ratios are used to guide resource allocation. discrete event simulation is an important tool for economic modeling of CAR-T as it is amenable to capturing the impact of wait-time, facilitating better understanding of factors affecting service delivery and consequently informed decision making to deliver faster access to CAR-T for patients.

Engineered polyspecific antibodies: A new frontier in the field of immunotherapeutics

The 21st-century beginning remarked with the huge success of monospecific MAbs, however, in the last couple of years, polyspecific MAbs (PsAbs) have been an interesting topic and show promise of being biobetter than monospecific MAbs. Polyspecificity, in which a single antibody serves multiple specific target binding, has been hypothesized to contribute to the development of a highly effective antibody repertoire for immune defence. This polyspecific MAb trend represents an explosion that is gripping the whole pharmaceutical industry. This review is concerned with the current development and quality enforcement of PsAbs. All provided literature on monospecific MAbs and polyspecific MAbs (PsAbs) were searched using various electronic databases such as PubMed, Google Scholar, Web of Science, Elsevier, Springer, ACS, Google Patent and books via the keywords Antibody engineering, Polyspecific antibody, Conventional antibody, non-conventional antibody, and Single domain antibody. In the literature, there are more than 100 different formats to construct PsAb by quadroma technology, chemical conjugation and genetic engineering. Till March 2023, nine PsAb have been approved around the world, and around 330 are in advanced developmental stages, showing the dominancy of PsAb in the growing health sector. Recent advancements in protein engineering techniques and the fusion of non-conventional antibodies have made it possible to create complex PsAbs that demonstrate higher stability and enhanced potency. This marks the most significant achievement for cancer immunotherapy, in which PsAbs have immense promise. It is worth mentioning that seven out of the nine PsAbs have been approved as anti-cancer therapy. As PsAbs continue to acquire prominence, they could pave the way for the development of novel immunotherapies for multiple diseases.

Single agent subcutaneous blinatumomab for advanced acute lymphoblastic leukemia

Blinatumomab is a BiTE® (bispecific T-cell engager) molecule that redirects CD3+ T-cells to engage and lyse CD19+ target cells. Here we demonstrate that subcutaneous (SC) blinatumomab can provide high efficacy and greater convenience of administration. In the expansion phase of a multi-institutional phase 1b trial (ClinicalTrials.gov, NCT04521231), heavily pretreated adults with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) received SC blinatumomab at two doses: (1) 250 μg once daily (QD) for week 1 and 500 μg three times weekly (TIW) thereafter (250 μg/500 μg) or (2) 500 μg QD for week 1 and 1000 μg TIW thereafter (500 μg/1000 μg). The primary endpoint was complete remission/complete remission with partial hematologic recovery (CR/CRh) within two cycles. At the data cutoff of September 15, 2023, 29 patients were treated: 14 at the 250 μg/500 μg dose and 13 at 500 μg/1000 μg dose. Data from two ineligible patients were excluded. At the end of two cycles, 12 of 14 patients (85.7%) from the 250 μg/500 μg dose achieved CR/CRh of which nine patients (75.0%) were negative for measurable residual disease (MRD; <10-4 leukemic blasts). At the 500 μg/1000 μg dose, 12 of 13 patients (92.3%) achieved CR/CRh; all 12 patients (100.0%) were MRD-negative. No treatment-related grade 4 cytokine release syndrome (CRS) or neurologic events (NEs) were reported. SC injections were well tolerated and all treatment-related grade 3 CRS and NEs responded to standard-of-care management, interruption, or discontinuation. Treatment with SC blinatumomab resulted in high efficacy, with high MRD-negativity rates and acceptable safety profile in heavily pretreated adults with R/R B-ALL.

Immune therapies of B-cell acute lymphoblastic leukaemia in children and adults

B-cell acute lymphoblastic leukaemia (B-cell ALL) is a common haematologic cancer in children and adults. About 10 percent of children and 50 percent of adults fail to achieve a histological complete remission or subsequently relapse despite current anti-leukaemia drug therapies and/or haematopoietic cell transplants. Several new immune therapies including monoclonal antibodies and chimeric antigen receptor (CAR)-T-cells are proved safe and effective in this setting. We review data on US Food and Drug Administration (FDA)-approved immune therapies for B-cell ALL in children and adults including blinatumomab, inotuzumab ozogamicin, tisagenlecleucel, and brexucabtagene autoleucel. We also summarize pharmaco-dynamics, pharmaco-kinetics, and pharmaco-economics of these interventions.

Infant Acute Lymphoblastic Leukemia-New Therapeutic Opportunities

Infant acute lymphoblastic leukemia (Infant ALL) is a kind of pediatric ALL, diagnosed in children under 1 year of age and accounts for less than 5% of pediatric ALL. In the infant ALL group, two subtypes can be distinguished: KMT2A-rearranged ALL, known as a more difficult to cure form and KMT2A- non-rearranged ALL with better survival outcomes. As infants with ALL have lesser treatment outcomes compared to older children, it is pivotal to provide novel treatment approaches. Progress in the development of molecularly targeted therapies and immunotherapy presents exciting opportunities for potential improvement. This comprehensive review synthesizes the current literature on the epidemiology, clinical presentation, molecular genetics, and therapeutic approaches specific to ALL in the infant population.

The Implementation of Chimeric Antigen Receptor (CAR) T-cell Therapy in Pediatric Patients: Where Did We Come From, Where Are We Now, and Where are We Going?

CD19-directed Chimeric Antigen Receptor (CAR) T-cell therapy has revolutionized the treatment of patients with B-cell acute lymphoblastic leukemia (B-ALL). Somewhat uniquely among oncologic clinical trials, early clinical development occurred simultaneously in both children and adults. In subsequent years however, the larger number of adult patients with relapsed/refractory (r/r) malignancies has led to accelerated development of multiple CAR T-cell products that target a variety of malignancies, resulting in six currently FDA-approved for adult patients. By comparison, only a single CAR-T cell therapy is approved by the FDA for pediatric patients: tisagenlecleucel, which is approved for patients ≤ 25 years with refractory B-cell precursor ALL, or B-cell ALL in second or later relapse. Tisagenlecleucel is also under evaluation in pediatric patients with relapsed/refractory B-cell non-Hodgkin lymphoma, but is not yet been approved for this indication. All the other FDA-approved CD19-directed CAR-T cell therapies available for adult patients (axicabtagene ciloleucel, brexucabtagene autoleucel, and lisocabtagene maraleucel) are currently under investigations among children, with preliminary results available in some cases. As the volume and complexity of data continue to grow, so too does the necessity of rapid assimilation and implementation of those data. This is particularly true when considering "atypical" situations, e.g. those arising when patients do not precisely conform to the profile of those included in pivotal clinical trials, or when alternative treatment options (e.g. hematopoietic stem cell transplantation (HSCT) or bispecific T-cell engagers (BITEs)) are also available. We have therefore developed a relevant summary of the currently available literature pertaining to the use of CD19-directed CAR-T cell therapies in pediatric patients, and sought to provide guidance for clinicians seeking additional data about specific clinical situations.

Cardiovascular toxicities associated with bispecific T-cell engager therapy

BACKGROUND

Bispecific T-cell engagers (BTEs) are novel agents used to treat hematological malignancies. Early trials were underpowered to define cardiovascular adverse events (CVAE) and no large-scale studies systematically examined the CVAEs associated with BTEs.

METHODS

Leveraging the US Food and Drug Administration's Adverse Event Reporting System-(FAERS), we identified the relative frequency of CVAEs after initiation of five BTE products approved by the Food and Drug Administration between 2014 and 2023 for the treatment of hematological malignancies. Adjusted reporting ORs (aROR) were used to identify disproportionate reporting of CVAEs with BTEs compared with background rates in the database. Fatality rates and risk ratios (RRs) for each adverse event (AE) were calculated.

RESULTS

From 3668 BTE-related cases reported to FAERS, 747 (20.4%) involved CVAEs. BTEs as a class were associated with fatal CVAEs (aROR 1.29 (95% CI 1.12 to 1.50)), an association mainly driven by teclistamab (aROR 2.44 (95% CI 1.65 to 3.60)). Teclistamab was also associated with a disproportionate risk of myocarditis (aROR 25.70 (95% CI 9.54 to 69.23)) and shock (aROR 3.63 (95% CI 2.30 to 5.74)), whereas blinatumomab was associated with a disproportionate risk of disseminated intravascular coagulation (aROR 3.02 (95% CI 1.98 to 4.60)) and hypotension (aROR 1.59 (95% CI 1.25 to 2.03)). CVAEs were more fatal compared with non-CVAEs (31.1% vs 17.4%; RR 1.76 (95% CI 1.54 to 2.03)). Most CVAEs (83.3%) did not overlap with cytokine release syndrome.

CONCLUSION

In the first postmarketing surveillance study of BTEs, CVAEs were involved in approximately one in five AE reports and carried a significant mortality risk.

Bispecific antibodies and CAR-T cells: dueling immunotherapies for large B-cell lymphomas

Despite recent advances in frontline therapy for diffuse large B-cell lymphoma (DLBCL), at least a third of those diagnosed still will require second or further lines for relapsed or refractory (rel/ref) disease. A small minority of these can be cured with standard chemoimmunotherapy/stem-cell transplant salvage approaches. CD19-directed chimeric antigen receptor T-cell (CAR-19) therapies are increasingly altering the prognostic landscape for rel/ref patients with DLBCL and related aggressive B-cell non-Hodgkin lymphomas. Long-term follow up data show ongoing disease-free outcomes consistent with cure in 30-40% after CAR-19, including high-risk patients primary refractory to or relapsing within 1 year of frontline treatment. This has made CAR-19 a preferred option for these difficult-to-treat populations. Widespread adoption, however, remains challenged by logistical and patient-related hurdles, including a requirement for certified tertiary care centers concentrated in urban centers, production times of at least 3-4 weeks, and high per-patients costs similar to allogeneic bone-marrow transplantation. Bispecific antibodies (BsAbs) are molecular biotherapies designed to bind and activate effector T-cells and drive them to B-cell antigens, leading to a similar cellular-dependent cytotoxicity as CAR-19. May and June of 2023 saw initial approvals of next-generation BsAbs glofitamab and epcoritamab in DLBCL as third or higher-line therapy, or for patients ineligible for CAR-19. BsAbs have similar spectrum but generally reduced severity of immune related side effects as CAR-19 and can be administered in community settings without need to manufacture patient-specific cellular products. To date and in contrast to CAR-19, however, there is no convincing evidence of cure after BsAbs monotherapy, though follow up is limited. The role of BsAbs in DLBCL treatment is rapidly evolving with trials investigating use in both relapsed and frontline curative-intent combinations. The future of DLBCL treatment is bound increasingly to include effector cell mediated immunotherapies, but further optimization of both cellular and BsAb approaches is needed.

Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia in Children: A Retrospective Cohort Study at a Pediatric Oncology Center

Background and objective Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL Ph+) is quite rare among pediatric patients. Its management has undergone significant changes in the past few years, leading to some variability in how it is approached. At the Portuguese Oncology Institute of Porto (IPOP), a tertiary oncological center, the standard of care has been aligned with the guidelines proposed by the European intergroup study of post-induction treatment of ALL Ph+ (EsPhALL). In this study, we aimed to examine the experience and outcomes related to the treatment of pediatric patients with ALL Ph+ at IPOP. Methods This retrospective cohort study involved pediatric patients diagnosed with ALL Ph+ at IPOP between January 2008 and December 2022 and analyzed their outcomes. Results A total of 14 patients were included. IKFZ1 was altered in five patients (out of nine in whom it was searched). Five patients were treated according to EsPhALL 2004, which involved starting imatinib later in a discontinuous manner [resulting in both five-year overall survival (OS) and progression-free survival (PFS) of 60%]. The EsPhALL 2010 (preconizing a continuous imatinib regimen instead) was employed in three patients, with a five-year OS and PFS of 66.7%. All children mentioned above received cranial irradiation therapy (CRT). Finally, six were treated according to the EsPhALL 2015, which stopped including CRT in its backbone. The five-year OS was 100%, whereas every patient progressed with an increase in BCR::ABL1 levels greater than 1-log. Moreover, until 2015, all patients had been recommended to undergo allogeneic hematopoietic stem cell transplantation (alloHSCT). However, since 2015, alloHSCT has been exclusively reserved for relapsed/refractory (R/R) disease or poor responders with positive measurable residual disease (MRD). In total, alloHSCT was performed in nine patients. Conclusions Although initially associated with a poor prognosis, the ALL Ph+ paradigm is drastically shifting. Further studies will hopefully clarify the outcomes in this population and help understand the role of central nervous system (CNS) prophylaxis, alloHSCT, and MRD quantification.

INSPIRED Symposium Part 4A: Access to CAR T Cell Therapy in Unique Populations with B Cell Acute Lymphoblastic Leukemia

The approval of tisagenlecleucel (tisa-cel) for use in children with B cell acute lymphoblastic leukemia (B-ALL) was based on the phase 2 ELIANA trial, a global registration study. However, the ELIANA trial excluded specific subsets of patients facing unique challenges and did not include a sufficient number of patients to adequately evaluate outcomes in rare subpopulations. Since the commercialization of tisa-cel, data have become available that support therapeutic indications beyond the specific cohorts previously eligible for chimeric antigen receptor (CAR) T cells targeted to CD19 (CD19 CAR-T) therapy on the registration clinical trial. Substantial real-world data and aggregate clinical trial data have addressed gaps in our understanding of response rates, longer-term efficacy, and toxicities associated with CD19 CAR-T in special populations and rare clinical scenarios. These include patients with central nervous system relapsed disease, who were excluded from ELIANA and other early CAR-T trials owing to concerns about risk of neurotoxicity that have not been born out. There is also interest in the use of CD19 CAR-T for very-high-risk patients earlier in the course of therapy, such as patients with persistent minimal residual disease after 2 cycles of upfront chemotherapy and patients with first relapse of B-ALL. However, these indications are not specified on the label for tisa-cel and historically were not included in eligibility criteria for most clinical trials; data addressing these populations are needed. Populations at high risk of relapse, including patients with high-risk cytogenetic lesions, infants with B-ALL, patients with trisomy 21, and young adults with B-ALL, also may benefit from earlier treatment with CD19 CAR-T. It is important to prospectively study patient-reported outcomes given the differential toxicity expected between CD19 CAR-T and the historic standard of care, hematopoietic cell transplantation. Now that CD19 CAR-T therapy is commercially available, studies evaluating potential access disparities created by this very expensive novel therapy are increasingly pressing.

Comparison of blinatumomab and CAR T-cell therapy in relapsed/refractory acute lymphoblastic leukemia: a systematic review and meta-analysis

OBJECTIVES

This study evaluated the benefits and risks of patients with refractory or relapsed acute lymphocytic leukemia (R/R ALL) treated with anti-CD19 chimeric antigen receptor (CAR) T-cell therapy and blinatumomab.

METHODS

PubMed, Web of Science, Embase, and the Cochrane Library were searched for relevant studies.

RESULTS

The pooled complete remission (CR) rate and minimal residual disease (MRD) negative rate were 48%, 31% for blinatumomab, and 86% and 80% for CAR T-cell therapy.

CONCLUSIONS

The CAR T-cell therapy group exhibited a higher likelihood of CR rate than the blinatumomab group in every analysis regardless of adjustment subgroups. CAR T-cell therapy was associated with a significantly prolonged overall survival (OS) and relapse-free survival (RFS) compared with blinatumomab (2-year OS 55% vs 25%; 2-year RFS 40% vs 22%). CAR T-cell therapy was more effective for achieving CR and bridging to allogeneic hematopoietic stem cell transplantation (allo-SCT) than blinatumomab (2-year OS 75% vs. 57%). An emerging role for blinatumomab is as a bridging agent pre-SCT, and for patients who achieve an MRD-negative state pre-SCT, post-SCT outcomes are expected to be the same as CAR-T. For adverse effects (AEs), blinatumomab was associated with a lower rate of grade ≥3 hematological toxicity, CRS, and neurological events.

Cerebral Spinal Fluid Parameters Following CD19-Targeted Therapies in Children and Young Adults

The presence of leukocytes in the cerebral spinal fluid (CSF) of patients with acute lymphoblastic leukemia may indicate a relapse in the central nervous system. CD19-directed immunotherapy may increase the blood-brain barrier permeability, leading to neurologic toxicity and infiltrate the CNS. We studied the CSF cell and protein content in 71 consecutive patients who received either CD19 chimeric antigen receptor T cells or blinatumomab. Responding patients had an incidence of 66% and 61% of pleocytosis following blinatumomab or chimeric antigen receptor T cells, respectively. CSF parameters did not correlate with toxicity or prior CNS disease. Routine CSF flow cytometry following immunotherapy to distinguish T-cell infiltration from CNS relapse should be considered.

Advancing Diagnostics and Therapy to Reach Universal Cure in Childhood ALL

Systemic combination chemotherapy and intrathecal chemotherapy markedly increased the survival rate of children with ALL. In the past two decades, the use of minimal (measurable) residual disease (MRD) measurements early in therapy improved risk group stratification with subsequent treatment intensifications for patients at high risk of relapse, and enabled a reduction of treatment for low-risk patients. The recent development of more sensitive MRD technologies may further affect risk stratification. Molecular genetic profiling has led to the discovery of many new subtypes and their driver genetic alterations. This increased our understanding of the biological basis of ALL, improved risk classification, and enabled implementation of precision medicine. In the past decade, immunotherapies, including bispecific antibodies, antibody-drug conjugates, and cellular therapies directed against surface proteins, led to more effective and less toxic therapies, replacing intensive chemotherapy courses and allogeneic stem-cell transplantation in patients with relapsed and refractory ALL, and are now being tested in newly diagnosed patients. It has taken 50-60 years to increase the cure rate in childhood ALL from 0% to 90% by stepwise improvements in chemotherapy. This review provides an overview of how the developments over the past 10-15 years mentioned above have significantly changed the diagnostic and treatment approach in ALL, and discusses how the integrated use of molecular and immunotherapeutic insights will very likely direct efforts to cure those children with ALL who are not cured today, and improve the quality of life for survivors who should have decades of life ahead. Future efforts must focus on making effective, yet very expensive, new technologies and therapies available to children with ALL worldwide.

Blinatumomab as salvage therapy in patients with relapsed/refractory B-ALL who have failed/progressed after anti-CD19-CAR T therapy

BACKGROUND

Anti-CD19 chimeric antigen receptors (CARs) T-cell therapy has been shown to have excellent efficacy in patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (ALL). But many patients are refractory to anti-CD19-CAR T-cell therapy or relapse again.

METHODS

Five patients with R/R B-ALL did not respond to anti-CD19-CAR T-cell therapy or had a disease progression again after CAR-T cell therapy. They received a salvage therapy of Blinatumomab. The clinical response, CD19 expression on ALL cells, the proportion of CD3+ T cells, level of cytokine levels of interleukin-6 (IL-6), hematological toxicity, grade of cytokine release syndrome (CRS), and immune effector cell-associated neurotoxic syndrome (ICANS) were observed in salvage therapy of Blinatumomab.

RESULTS

Four patients obtained CR/CRi, even in patients without high expression of CD19 in B-ALL cells, while the other patient received NR after Blinatumomab therapy. The CD19 expression on ALL cells, the proportion of CD3+ T cells, and CD3+CD8+ T cells were deficient in Pt 5, who obtained PR in Blinatumomab therapy. One patient (Pt 3) was diagnosed with grade 0 hematological toxicity. The other four patients were diagnosed with grades 2-3 of hematological toxicity. The CRS was grade 0/one patient, grade 1/three, and grade 2/one. The ICANS was grade 0/four patients, grade 1/one. Rhizopus microsporus pneumonia and cryptococcal encephalopathy in two patients were controlled during Blinatumomab therapy.

CONCLUSIONS

Blinatumomab could be an effective and safe salvage therapy in patients with R/R B-ALL who failed/progressed after anti-CD19-CAR T therapy, even in R/R B-ALL patients without high expression of CD19 in B-ALL cells, patients with CNS leukemia or co-infection.Key messagesSome R/R B-ALL patients did not respond to anti-CD19 CAR T-cell therapy or had a disease progression again. Effective and safe salvage therapy for such patients remains to be explored.Blinatumomab could be an effective and safe salvage therapy in patients with R/R B-ALL who failed/progressed after anti-CD19-CAR T therapy, even in patients without high expression of CD19 in B-ALL cells.Blinatumomab could be an effective and safe salvage therapy in patients with R/R B-ALL who failed/progressed after anti-CD19-CAR T therapy, even in patients with CNS leukemia or co-infection.

Ex-vivo CS1-OKT3 dual specific bivalent antibody-armed effector T cells mediate cellular immunity against multiple myeloma

Bispecific T cell engaging antibodies (bsAbs) have emerged as novel and powerful therapeutic agents for redirecting T cells towards antigen-specific tumor killing. The cell surface glycoprotein and SLAM family member, CS1, exhibits stable and high-level expression on malignant plasma cells including multiple myeloma, which is indicative of an ideal target for bsAb therapy. Here, we developed a CS1 bsAb (CS1-dbBiTE) using Click chemistry to conjugate intact anti-CS1 antibody (Elotuzumab) and anti-huOKT3 antibody at their respective hinge regions. Using a cellular therapy approach, human T cells were armed ex-vivo with CS1-dbBiTE prior to examining effector activity. Our data indicates that arming T cells with CS1-dbBiTE induced T cell activation and expansion and subsequent cytotoxic activity against CS1-bearing MM tumors, demonstrated by significant CD107a expression as well as inflammatory cytokine secretion. As expected, CS1-dbBiTE armed T cells showed significantly reduced effector activity in the absence of CS1 expression. Similarly, in MM mouse xenograft studies, armed T cells exhibited effective anti-tumor efficacy highlighted by reduced tumor burden in MM.1S tumor-bearing mice compared to controls. On the basis of these findings, the rationale for CS1 targeting by human T cells armed with CS1-dbBiTE presents a potentially effective therapeutic approach for targeting MM.

Delivery of Care for Pediatric Patients Receiving Blinatumomab: A Children's Oncology Group Study

BACKGROUND

Blinatumomab is an immunotherapy agent used in pediatric oncology for the treatment of B-lineage acute lymphoblastic leukemia. Administration of blinatumomab, via continuous 28-day infusion cycles, can present multiple decision points and challenges related to patient care. Nurses are at the forefront of coordinating and delivering care for patients receiving blinatumomab.

OBJECTIVE

To describe the current state of practice across Children's Oncology Group (COG) member institutions regarding blinatumomab administration in both inpatient and home/outpatient settings.

METHODS

Between August and December 2021, a cross-sectional survey was used to determine current institutional practices related to blinatumomab administration. A single targeted respondent who was actively engaged in coordinating blinatumomab administration completed the survey on behalf of each COG institution.

RESULTS

Survey participation rate was 78% (150/192). During the first 28-day blinatumomab cycle, 71 institutions (53%) reported patient hospital stays between 73 hours and 7 days; 42 (31%) reported hospital stays ≤72 hours, and only 12 (9%) reported hospitalization for the full 28-day infusion. Small- to medium-size institutions were more likely to report longer hospitalizations (P = .03). Most blinatumomab administration occurred in the outpatient setting, with low rates of unplanned clinic/emergency room visits.

CONCLUSIONS

The majority of COG institutions have navigated the complex coordination of care required for children to receive blinatumomab at home. Wide variations in practice were noted across institutions.

IMPLICATIONS FOR PRACTICE

This study describes current institutional practices surrounding administration of 28-day blinatumomab infusions in children with leukemia and offers a starting point for institutional benchmarking and standardization of practice.

Case Report: CD19 and CD20 monoclonal antibodies with sequential chemotherapy for refractory acute B-lymphocytic leukemia in children

Objective

This paper observes the efficacy of chemotherapy combined with CD19 and CD20 monoclonal antibodies in clearing minimal residual disease (MRD) and bridging transplantation for refractory acute B-lymphoblastic leukemia (B-ALL) in children and reviews the literature.

Methods

A 4-year-old boy diagnosed with B-ALL in our hospital was treated with the SCCLG-ALL-2016 protocol. MRD and gene quantification decreased after induction but remained persistently positive, with poor efficacy. After this patient received three cycles of consolidation chemotherapy combined with blinatumomab and rituximab, MRD and fusion gene quantification became negative, and he received allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Results

During the use of monoclonal antibodies, neurotoxicity, CRS, or other side effects did not occur. Before transplantation, MRD became negative, and the bone marrow had been in complete remission since transplantation (13 months).

Conclusion

Chemotherapy combined with blinatumomab for refractory B-ALL in children can bring a better remission rate for patients and is a means of bridging transplantation. Nevertheless, sequential CD20 monoclonal antibody therapy is the first report , and no adverse effects were observed in our case. It is well tolerated and can be used as one of the treatments for refractory B-ALL.

Blinatumomab Redirects Donor Lymphocytes against CD19+ Acute Lymphoblastic Leukemia without Relevant Bystander Alloreactivity after Haploidentical Hematopoietic Stem Cell Transplantation

Blinatumomab alone or with donor leukocyte infusions (DLI) has been used after allogeneic hematopoietic stem cell transplantation (HSCT) as a salvage therapy in relapsing patients with CD19+ hematological malignancies. It was effective in a fraction of them, with low incidence of Graft-versus-Host Disease (GvHD). Immunosuppressive drugs used as GvHD prophylaxis hinder T cell function and reduce the efficacy of the treatment. Because T cell-depleted haploidentical HSCT with donor regulatory and conventional T cells (Treg/Tcon haploidentical HSCT) does not require post-transplant immunosuppression, it is an ideal platform for the concomitant use of blinatumomab and DLI. However, the risk of GvHD is high because the donor is haploidentical. We treated two patients with CD19+ acute lymphoblastic leukemia (ALL) who had relapsed after Treg/Tcon haploidentical HSCT with blinatumomab and DLI. Despite the mismatch for one HLA haplotype, they did not develop GvHD and achieved complete remission with negative minimal residual disease. Consistently, we found that blinatumomab did not enhance T cell alloreactivity in vitro. Eventually, the two patients relapsed again because of their high disease risk. This study suggests that treatment with blinatumomab and DLI can be feasible to treat relapse after haploidentical transplantation, and its pre-emptive use should be considered to improve efficacy.

Implications of Immunotherapy for Pediatric Malignancies: A Summary from the APSA Cancer Committee

Although survival for many pediatric cancers has improved with advances in conventional chemotherapeutic regimens and surgical techniques in the last several decades, it remains a leading cause of disease-related death in children. Outcomes in patients with recurrent, refractory, or metastatic disease are especially poor. Recently, the advent of alternative classes of therapies, including immunotherapies, have revolutionized systemic treatment for pediatric malignancies. Several classes of immunotherapies, including chimeric antigen receptor (CAR) T cell therapy, transgenic T-cell receptor (TCR)-T cell therapy, bispecific T-cell engagers, and monoclonal antibody checkpoint inhibitors have been FDA-approved or entered early-phase clinical trials in children and young adults. The pediatric surgeon is likely to encounter these therapies during the care of children with malignancies and should be familiar with the classes of therapy, indications, adverse events, and potential need for surgical intervention in these cases. This review from the APSA Cancer Committee offers a brief discussion of the three most encountered classes of immunotherapy in children and young adults and discusses surgical relevance. LEVEL OF EVIDENCE: IV.

Immune Surveillance of Acute Myeloid Leukemia Is Mediated by HLA-Presented Antigens on Leukemia Progenitor Cells

Therapy-resistant leukemia stem and progenitor cells (LSC) are a main cause of acute myeloid leukemia (AML) relapse. LSC-targeting therapies may thus improve outcome of patients with AML. Here we demonstrate that LSCs present HLA-restricted antigens that induce T-cell responses allowing for immune surveillance of AML. Using a mass spectrometry-based immunopeptidomics approach, we characterized the antigenic landscape of patient LSCs and identified AML- and AML/LSC-associated HLA-presented antigens absent from normal tissues comprising nonmutated peptides, cryptic neoepitopes, and neoepitopes of common AML driver mutations of NPM1 and IDH2. Functional relevance of shared AML/LSC antigens is illustrated by presence of their cognizant memory T cells in patients. Antigen-specific T-cell recognition and HLA class II immunopeptidome diversity correlated with clinical outcome. Together, these antigens shared among AML and LSCs represent prime targets for T cell-based therapies with potential of eliminating residual LSCs in patients with AML.

SIGNIFICANCE

The elimination of therapy-resistant leukemia stem and progenitor cells (LSC) remains a major challenge in the treatment of AML. This study identifies and functionally validates LSC-associated HLA class I and HLA class II-presented antigens, paving the way to the development of LSC-directed T cell-based immunotherapeutic approaches for patients with AML. See related commentary by Ritz, p. 430 . This article is featured in Selected Articles from This Issue, p. 419.

Case Report: Blinatumomab as upfront consolidation and maintenance therapy in a pediatric patient with high-risk B-cell acute lymphoblastic leukemia

Introduction

B-cell acute lymphoblastic leukemia (B-ALL) is the most common malignancy in children. The current conventional chemotherapy regimens have high overall survival but with significant short- and long-term toxicities, sometimes requiring delay and termination of chemotherapy. Bispecific T-cell engager antibody blinatumomab has been successful in achieving bone marrow remission and acting as bridging therapy in minimal residual disease (MRD)-positive relapsed adult and pediatric B-ALL patients. Its role as upfront therapy is being explored. Here, we report the first case to our knowledge showing the feasibility, tolerability, and sustained remission using blinatumomab upfront as consolidation and maintenance therapy for 2 years in a pediatric patient with high-risk B-ALL who had significant toxicities with conventional chemotherapy.

'Case presentation

An 11-year-old Hispanic girl presented with complaints of fever, abdominal pain, and fatigue. On further evaluation, she had tachycardia, pallor, cervical lymphadenopathy, and pancytopenia. Bone marrow studies confirmed high-risk B-ALL. The patient was started on induction chemotherapy per AALL1131. Her induction course was complicated by syncope, febrile neutropenia, and invasive cryptococcal fungal infection. End-of-induction bone marrow results were MRD negative. Further chemotherapy was withheld due to cardiopulmonary and renal failure, along with ventricular arrhythmias requiring intensive care. The patient received two cycles of blinatumomab as consolidation therapy and then transitioned back to conventional consolidation therapy; however, it was terminated mid-consolidation due to Pseudomonas and Aspergillus sepsis. She was then given blinatumomab maintenance therapy for 2 years and tolerated it well without any irreversible toxicity. She had an episode of Staphylococcus epidermidis sepsis and pneumonia treated by antibiotics and a single episode of a seizure while on blinatumomab therapy. At the time of publication, she is 25 months off treatment and in sustained remission without any further transplant or chemotherapy. She received monthly intravenous immunoglobulin G during the blinatumomab maintenance.

Conclusion

Blinatumomab given upfront as consolidation and maintenance therapy for 2 years in a pediatric high-risk B-ALL patient with significant toxicities to conventional chemotherapy was feasible and very well tolerated without any irreversible toxicity and led to sustained remission without any bridging transplant or further chemotherapy.

Survival outcomes in patients with relapsed/refractory or MRD-positive B-cell acute lymphoblastic leukemia treated with blinatumomab

Blinatumomab has demonstrated significant efficacy in adult and pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-cell ALL) and patients with measurable residual disease (MRD). This review aimed to compare median relapse-free survival (RFS) and median overall survival (OS) in adult and pediatric patients with R/R or MRD-positive B-cell ALL from pivotal studies [MT-103-211 and TOWER for adults with Philadelphia chromosome (Ph)-negative R/R B-cell ALL, ALCANTARA for adults with Ph-positive R/R B-cell ALL, MT-103-203 for adults with MRD-positive B-cell ALL, and MT-103-205 for pediatric patients with R/R B-cell ALL], with the median RFS and OS from retrospective analyses, country or ethnicity-specific studies, and studies based on real-world evidence (RWE) identified from a literature search. Adults with Ph-negative R/R B-cell ALL who received blinatumomab as first salvage demonstrated a numerically longer median OS compared with that in patients from pivotal studies (MT-103-211 and TOWER) without additional safety concerns. In pediatric patients with R/R B-cell ALL treated with blinatumomab, the median RFS and OS from retrospective analyses and country/ethnicity-specific studies were comparable with the median RFS and OS from the pivotal study MT-103-205. The median RFS and OS from RWE studies in adults with R/R B-cell ALL were numerically longer than the median RFS and OS from pivotal studies (MT-103-211, TOWER, and ALCANTARA); however, this trend was not observed in pediatric patients with R/R B-cell ALL. In conclusion, this analysis identified first salvage adults with Ph-negative R/R B-cell ALL as particularly well-suited for treatment with blinatumomab since survival outcomes from retrospective analyses reported in this patient subgroup were numerically better compared with those from pivotal studies without additional safety signals.

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.

Outcome of hematopoietic stem cell transplantation in pediatric patients with acute lymphoblastic leukemia not in remission enrolled in JACLS ALL-02

Hematopoietic stem cell transplantation (HSCT) is only indicated for acute lymphoblastic leukemia (ALL) patients for whom other treatments are unlikely to be curative. However, outcomes of patients not in complete remission (CR) at HSCT remain very poor. To improve the outcomes of patients receiving HSCT, it is important to obtain detailed clinical information about patients with ALL receiving HSCT in CR and not in CR. Patients enrolled in the Japan Association of Childhood Leukemia Study ALL-02 who underwent HSCT and were not in CR (non-CR patients, n = 55) were examined. The 1-year overall survival (OS) rate of non-CR patients was 27.3%. Compared with CR patients, non-CR patients experienced very early and early relapse significantly more frequently and had poorer prognostic factors. Most interestingly, high hyperdiploid (HHD) patients showed an excellent 1-year OS of 80%. In addition, long-term survival among surviving HHD patients was longer than 5 years. All eight patients who survived after undergoing HSCT while not in CR were younger than 10 years at initial diagnosis and were negative for central nervous system involvement. While limited, these results suggest that a subset of patients may benefit from HSCT while not in CR.

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

PURPOSE

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Children's Oncology Group blueprint for research: Acute lymphoblastic leukemia

Cure rates for acute lymphoblastic leukemia (ALL), the most common childhood cancer have steadily improved over the past five decades. This is due to intensifying systemic therapy, recognizing and treating the central nervous system as a sanctuary site, and implementing modern risk stratification to deliver varying intensities of therapy based on age, presenting white blood count, sentinel somatic genetics, and therapy response. Recently, numerous Children's Oncology Group trials have demonstrated the lack of benefit of intensifying traditional chemotherapy, providing evidence that new approaches are needed to cure the patients for whom cure has been elusive. Distinguishing those who require intensive or novel therapeutic approaches from others who will be cured with minimal therapy is key for future trials. Incorporating new genomic biomarkers and more sensitive measures of minimal/measurable residual disease provide opportunities to achieve these goals.

Bi- and trispecific immune cell engagers for immunotherapy of hematological malignancies

Immune cell engagers are engineered antibodies with at least one arm binding a tumor-associated antigen and at least another one directed against an activating receptor in immune effector cells: CD3 for recruitment of T cells and CD16a for NK cells. The first T cell engager (the anti-CD19 blinatumomab) was approved by the FDA in 2014, but no other one hit the market until 2022. Now the field is gaining momentum, with three approvals in 2022 and 2023 (as of May): the anti-CD20 × anti-CD3 mosunetuzumab and epcoritamab and the anti-B cell maturation antigen (BCMA) × anti-CD3 teclistamab, and another three molecules in regulatory review. T cell engagers will likely revolutionize the treatment of hematological malignancies in the short term, as they are considerably more potent than conventional monoclonal antibodies recognizing the same tumor antigens. The field is thriving, with a plethora of different formats and targets, and around 100 bispecific T cell engagers more are already in clinical trials. Bispecific NK cell engagers are also in early-stage clinical studies and may offer similar efficacy with milder side effects. Trispecific antibodies (engaging either T cell or NK cell receptors) raise the game even further with a third binding moiety, which allows either the targeting of an additional tumor-associated antigen to increase specificity and avoid immune escape or the targeting of additional costimulatory receptors on the immune cell to improve its effector functions. Altogether, these engineered molecules may change the paradigm of treatment for relapsed or refractory hematological malignancies.

Bispecific antibody targeting TGF-β and PD-L1 for synergistic cancer immunotherapy

The PD-1/PD-L1 signaling pathway plays a crucial role in cancer immune evasion, and the use of anti-PD-1/PD-L1 antibodies represents a significant milestone in cancer immunotherapy. However, the low response rate observed in unselected patients and the development of therapeutic resistance remain major obstacles to their clinical application. Accumulating studies showed that overexpressed TGF-β is another immunosuppressive factor apart from traditional immune checkpoints. Actually, the effects of PD-1 and TGF-β pathways are independent and interactive, which work together contributing to the immune evasion of cancer cell. It has been verified that blocking TGF-β and PD-L1 simultaneously could enhance the efficacy of PD-L1 monoclonal antibody and overcome its treatment resistance. Based on the bispecific antibody or fusion protein technology, multiple bispecific and bifunctional antibodies have been developed. In the preclinical and clinical studies, these updated antibodies exhibited potent anti-tumor activity, superior to anti-PD-1/PD-L1 monotherapies. In the review, we summarized the advances of bispecific antibodies targeting TGF-β and PD-L1 in cancer immunotherapy. We believe these next-generation immune checkpoint inhibitors would substantially alter the cancer treatment paradigm, especially in anti-PD-1/PD-L1-resistant patients.

T-cell-engaging bispecific antibodies in cancer

T-cell-engaging bispecific antibodies (BsAbs) simultaneously bind to antigens on tumour cells and CD3 subunits on T cells. This simultaneous binding results in the recruitment of T cells to the tumour, followed by T-cell activation and degranulation, and tumour cell elimination. T-cell-engaging BsAbs have shown substantial activity in several haematological malignancies by targeting CD19 in acute lymphoblastic leukaemia, CD20 in B-cell non-Hodgkin lymphoma, and BCMA and GPRC5D in multiple myeloma. Progress with solid tumours has been slower, in part due to the paucity of therapeutic targets with a tumour-specific expression profile, which is needed to limit on-target off-tumour side-effects. Nevertheless, BsAb-mediated recognition of a peptide fragment of gp100 presented by HLA-A2:01 molecules has shown marked activity in patients with unresectable or metastatic uveal melanoma. Cytokine release syndrome is the most frequent toxicity associated with BsAb treatment and is caused by activated T cells secreting proinflammatory cytokines. Understanding of resistance mechanisms has resulted in the development of new T cell-redirecting formats and novel combination strategies, which are expected to further improve depth and duration of response.

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.

Engineering strategies of Anti-HIV antibody therapeutics in clinical development

PURPOSE OF REVIEW

Anti-human immunodeficiency virus (HIV) antibody-based therapeutics offer an alternative treatment option to current antiretroviral drugs. This review aims to provide an overview of the Fc- and Fab-engineering strategies that have been developed to optimize broadly neutralizing antibodies and discuss recent findings from preclinical and clinical studies.

RECENT FINDINGS

Multispecific antibodies, including bispecific and trispecific antibodies, DART molecules, and BiTEs, as well as Fc-optimized antibodies, have emerged as promising therapeutic candidates for the treatment of HIV. These engineered antibodies engage multiple epitopes on the HIV envelope protein and human receptors, resulting in increased potency and breadth of activity. Additionally, Fc-enhanced antibodies have demonstrated extended half-life and improved effector function.

SUMMARY

The development of Fc and Fab-engineered antibodies for the treatment of HIV continues to show promising progress. These novel therapies have the potential to overcome the limitations of current antiretroviral pharmacologic agents by more effectively suppressing viral load and targeting latent reservoirs in individuals living with HIV. Further studies are needed to fully understand the safety and efficacy of these therapies, but the growing body of evidence supports their potential as a new class of therapeutics for the treatment of HIV.

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.