Outcome of relapsed infant acute lymphoblastic leukemia treated on the interfant-99 protocol

Menin inhibitors in pediatric acute leukemia: a comprehensive review and recommendations to accelerate progress in collaboration with adult leukemia and the international community

Aberrant expression of HOX and MEIS1 family genes, as seen in KMT2A-rearranged, NUP98-rearranged, or NPM1-mutated leukemias leads to arrested differentiation and leukemia development. HOX family genes are essential gatekeepers of physiologic hematopoiesis, and their expression is regulated by the interaction between KMT2A and menin. Menin inhibitors block this interaction, downregulate the abnormal expression of MEIS1 and other transcription factors and thereby release the differentiation block. Menin inhibitors show significant clinical efficacy against KMT2A-rearranged and NPM1-mutated acute leukemias, with promising potential to address unmet needs in various pediatric leukemia subtypes. In this collaborative initiative, pediatric and adult hematologists/oncologists, and stem cell transplant physicians have united their expertise to explore the potential of menin inhibitors in pediatric leukemia treatment internationally. Our efforts aim to provide a comprehensive clinical overview of menin inhibitors, integrating preclinical evidence and insights from ongoing global clinical trials. Additionally, we propose future international, inclusive, and efficient clinical trial designs, integrating pediatric populations in adult trials, to ensure broad access to this promising therapy for all children and adolescents with menin-dependent leukemias.

Menin Inhibition With Revumenib for KMT2A-Rearranged Relapsed or Refractory Acute Leukemia (AUGMENT-101)

PURPOSE

Revumenib, an oral, small molecule inhibitor of the menin-lysine methyltransferase 2A (KMT2A) interaction, showed promising efficacy and safety in a phase I study of heavily pretreated patients with KMT2A-rearranged (KMT2Ar) acute leukemia. Here, we evaluated the activity of revumenib in individuals with relapsed/refractory (R/R) KMT2Ar acute leukemia.

METHODS

AUGMENT-101 is a phase I/II, open-label, dose-escalation and expansion study of revumenib conducted across 22 clinical sites in five countries (ClinicalTrials.gov identifier: NCT04065399). We report results from the phase II, registration-enabling portion. Individuals age ≥30 days with R/R KMT2Ar acute leukemia or with AML and nucleophosmin 1 (NPM1) mutation were enrolled. Revumenib was administered once every 12 hours, at 163 mg (95 mg/m2 if weight <40 kg) with a strong cytochrome P450 inhibitor, in 28-day cycles. The primary end points were the rate of complete remission (CR) or CR with partial hematologic recovery (CR + CRh) and safety. At a prespecified interim analysis, safety was assessed in all KMT2Ar treated patients; efficacy was assessed in those with centrally confirmed KMT2Ar. The separate NPM1 cohort of the trial is ongoing.

RESULTS

From October 1, 2021, to July 24, 2023, N = 94 patients (median [range] age, 37 [1.3-75] years) were treated. Grade ≥3 adverse events included febrile neutropenia (37.2%), differentiation syndrome (16.0%), and QTc prolongation (13.8%). In the efficacy-evaluable patients (n = 57), the CR + CRh rate was 22.8% (95% CI, 12.7 to 35.8), exceeding the null hypothesis of 10% (P = .0036). Overall response rate was 63.2% (95% CI, 49.3 to 75.6), with 15 of 22 patients (68.2%) having no detectable residual disease.

CONCLUSION

Revumenib led to high remission rates with a predictable safety profile in R/R KMT2Ar acute leukemia. To our knowledge, this trial represents the largest evaluation of a targeted therapy for these patients.

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.

Successful Retransplantation With Killer Cell Immunoglobulin-like Receptor Ligand-mismatched Cord Blood in Infant Acute Lymphoblastic Leukemia That Relapsed After Transplantation

The prognosis of children with KMT2A -rearranged ( KMT2A -r) acute lymphoblastic leukemia (ALL) remains dismal. This report describes the successful retransplantation of a patient with infant ALL who relapsed both bone marrow and central nervous system. The patient received HLA-matched cord blood transplantation (CBT) and relapsed 18 months later. After achieving the second remission, the patient received a killer cell immunoglobulin-like receptor ligand-mismatched CBT with a reduced-intensity conditioning regimen and has been in remission for 52 months. Thus, killer cell immunoglobulin-like receptor ligand-mismatched CBT with reduced-intensity conditioning might be a treatment option for patients with KMT2A- r ALL who relapsed after transplantation, even with extramedullary relapse.

The EGR3 regulome of infant KMT2A-r acute lymphoblastic leukemia identifies differential expression of B-lineage genes predictive for outcome

KMT2A-rearranged acute lymphoblastic infant leukemia (KMT2A-r iALL) is associated with outsize risk of relapse and relapse mortality. We previously reported strong upregulation of the immediate early gene EGR3 in KMT2A::AFF1 iALL at relapse; now we provide analyses of the EGR3 regulome, which we assessed through binding and expression target analysis of an EGR3-overexpressing t(4;11) cell culture model. Our data identify EGR3 as a regulator of early B-lineage commitment. Principal component analysis of 50 KMT2A-r iALL patients at diagnosis and 18 at relapse provided strictly dichotomous separation of patients based on the expression of four B-lineage genes. Absence of B-lineage gene expression translates to more than two-fold poorer long-term event-free survival. In conclusion, our study presents four B-lineage genes with prognostic significance, suitable for gene expression-based risk stratification of KMT2A-r iALL patients.

Tisagenlecleucel therapy for relapsed or refractory B-cell acute lymphoblastic leukaemia in infants and children younger than 3 years of age at screening: an international, multicentre, retrospective cohort study

BACKGROUND

Children aged younger than 3 years were excluded from the ELIANA phase 2 trial of tisagenlecleucel in children with acute lymphoblastic leukaemia. The feasibility, safety, and activity of tisagenlecleucel have not been defined in this group, the majority of whom have high-risk (KMT2A-rearranged) infant acute lymphoblastic leukaemia and historically poor outcomes despite intensification of chemotherapy, and for whom novel therapies are urgently needed. We aimed to provide real-world outcome analysis of the feasibility, activity, and safety of tisagenlecleucel in younger children and infants with acute lymphoblastic leukaemia.

METHODS

We did an international, multicentre, retrospective cohort study at 15 hospitals across ten countries in Europe. Eligible patients were children aged younger than 3 years at screening between Sept 1, 2018, and Sept 1, 2021, who were screened for tisagenlecleucel therapy for relapsed or refractory B-cell precursor acute lymphoblastic leukaemia according to licensed indications. Patients received a single intravenous infusion of tisagenlecleucel. We tracked chimeric antigen receptor T-cell therapy outcomes using a standardised data reporting form. Overall survival, event-free survival, stringent event-free survival, B-cell aplasia, and toxicity were assessed in all patients who received a tisagenlecleucel infusion.

FINDINGS

38 eligible patients were screened, of whom 35 (92%) received a tisagenlecleucel infusion. 29 (76%) of 38 patients had KMT2A-rearranged acute lymphoblastic leukaemia, and 25 (66%) had relapsed after previous allogeneic haematopoietic stem-cell transplantation (HSCT). Patients had previously received a median of 2 lines (IQR 2-3) of (non-HSCT) therapy. Seven (18%) of 38 patients had received inotuzumab and 14 (37%) had received blinatumomab. After a median of 14 months (IQR 9-21) of follow-up, overall survival at 12 months after tisagenlecleucel infusion was 84% (64-93; five patients had died), event-free survival was 69% (47-83; nine events), and stringent event-free survival was 41% (23-58; 18 events). The probability of ongoing B-cell aplasia was 70% (95% CI 46-84; seven events) at 12 months. Adverse events included cytokine release syndrome, which occurred at any grade in 21 (60%) of 35 patients and at grade 3 or worse in five (14%), and neurotoxicity at any grade in nine (26%), none of which were severe. Measurable residual disease-negative complete response with or without haematological recovery occurred in 24 (86%) of 28 patients who had measurable disease.

INTERPRETATION

These data suggest that tisagenlecleucel has antitumour activity and has an acceptable safety profile for young children and infants with B-cell precursor acute lymphoblastic leukaemia.

FUNDING

None.

The immune checkpoint ICOSLG is a relapse-predicting biomarker and therapeutic target in infant t(4;11) acute lymphoblastic leukemia

The most frequent genetic aberration leading to infant ALL (iALL) is the chromosomal translocation t(4;11), generating the fusion oncogenes KMT2A:AFF1 and AFF1:KMT2A, respectively. KMT2A-r iALL displays a dismal prognosis through high relapse rates and relapse-associated mortality. Relapse occurs frequently despite ongoing chemotherapy and without the accumulation of secondary mutations. A rational explanation for the observed chemo-resistance and satisfactory treatment options remain to be elucidated. We found that elevated ICOSLG expression level at diagnosis was associated with inferior event free survival (EFS) in a cohort of 43 patients with t(4;-11) iALL and that a cohort of 18 patients with iALL at relapse displayed strongly increased ICOSLG expression. Furthermore, co-culturing t(4;11) ALL cells (ICOSLG^hi) with primary T-cells resulted in the development of T_regs. This was impaired through treatment with a neutralizing ICOSLG antibody. These findings imply ICOSLG (1) as a relapse-predicting biomarker, and (2) as a therapeutic target involved in a potential immune evasion relapse-mechanism of infant t(4;11) ALL.

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Early growth response 3 (EGR3) is a direct transactivator of the immune checkpoint gene ICOSLG

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high ICOSLG expression at diagnosis is predictive for ALL relapse

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EGR3 and ICOSLG expressions are relapse-associated

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expression of ICOSLG on t(4;11) ALL cells leads to the rapid expansion of Tregs

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Relapsed acute lymphoblastic leukaemia after allogeneic stem cell transplantation: a therapeutic dilemma challenging the armamentarium of immunotherapies currently available (case reports)

While survival rates in paediatric acute lymphoblastic leukaemia (ALL) nowadays exceed 90%, systemic ALL relapse, especially after haemopoietic stem cell transplantation (HSCT), is associated with a poor outcome. As there is currently no standardized treatment for this situation, individualized treatment is often pursued. Exemplified by two clinical scenarios, the aim of this article is to highlight the challenge for treating physicians to find a customized treatment strategy integrating the role of conventional chemotherapy, immunotherapeutic approaches and second allogeneic HSCT. Case 1 describes a 2-year-old girl with an early isolated bone marrow relapse of an infant KMT2A-rearranged B-cell precursor ALL after allogeneic HSCT. After bridging chemotherapy and lymphodepleting chemotherapy, chimeric antigen receptor (CAR) T-cells (tisagenlecleucel) were administered for remission induction, followed by a second HSCT from the 9/10 human leukocyte antigen (HLA)-matched mother. Case 2 describes a 16-year-old girl with a late, isolated bone marrow relapse of B-cell precursor ALL after allogeneic HSCT who experienced severe treatment toxicities including stage IV renal insufficiency. After dose-reduced bridging chemotherapy, CAR T-cells (tisagenlecleucel) were administered for remission induction despite a CD19^- clone without prior lymphodepletion due to enhanced persisting toxicity. This was followed by a second allogeneic HSCT from the haploidentical mother. While patient 2 relapsed around Day + 180 after the second HSCT, patient 1 is still in complete remission >360 days after the second HSCT. Both cases demonstrate the challenges associated with systemic ALL relapse after first allogeneic HSCT, including chemotherapy-resistant disease and persisting organ damage inflicted by previous therapy. Immunotherapeutic approaches, such as CAR T-cells, can induce remission and enable a second allogeneic HSCT. However, optimal therapy for systemic ALL relapse after first HSCT remains to be defined.

Real-World Use of Tisagenlecleucel in Infant Acute Lymphoblastic Leukemia

Infants with B-cell acute lymphoblastic leukemia (B-ALL) have poor outcomes due to chemotherapy resistance leading to high relapse rates. Tisagenlecleucel, a CD19-directed chimeric antigen receptor T-cell (CART) therapy, is FDA approved for relapsed or refractory (R/R) B-ALL in patients ≤25 years; however, the safety and efficacy of this therapy in young patients is largely unknown since children <3 years of age were excluded from licensing studies. We retrospectively evaluated data from the Pediatric Real-World CAR Consortium to examine outcomes of patients with infant B-ALL who received tisagenlecleucel between 2017 and 2020 (n=14). Sixty-four percent of patients (n=9) achieved minimal residual disease (MRD)-negative remission post-CART and 50% of patients remain in remission at last follow-up. All patients with high disease burden at time of CART infusion (>M1 marrow) were refractory to this therapy (n=5). Overall, tisagenlecleucel was tolerable in this population, with only 3 patients experiencing > grade 3 cytokine release syndrome. No neurotoxicity was reported. This is the largest report of tisagenlecleucel use in infant B-ALL and shows that this therapy is safe and can be effective in this population. Incorporating this novel immunotherapy into the treatment of infant B-ALL offers a promising therapy for a highly aggressive leukemia.

Recent Advances in Treatment Options for Childhood Acute Lymphoblastic Leukemia

Simple Summary

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

Abstract

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

Impact of high-risk cytogenetics on outcomes for children and young adults receiving CD19-directed CAR T-cell therapy

Chimeric antigen receptor (CAR) T-cell therapy can induce durable remissions of relapsed/refractory B-acute lymphoblastic leukemia (ALL). However, case reports suggested differential outcomes mediated by leukemia cytogenetics. We identified children and young adults with relapsed/refractory CD19+ ALL/lymphoblastic lymphoma treated on 5 CD19-directed CAR T-cell (CTL019 or humanized CART19) clinical trials or with commercial tisagenlecleucel from April 2012 to April 2019. Patients were hierarchically categorized according to leukemia cytogenetics: High-risk lesions were defined as KMT2A (MLL) rearrangements, Philadelphia chromosome (Ph+), Ph-like, hypodiploidy, or TCF3/HLF; favorable as hyperdiploidy or ETV6/RUNX1; and intermediate as iAMP21, IKZF1 deletion, or TCF3/PBX1. Of 231 patients aged 1 to 29, 74 (32%) were categorized as high risk, 28 (12%) as intermediate, 43 (19%) as favorable, and 86 (37%) as uninformative. Overall complete remission rate was 94%, with no difference between strata. There was no difference in relapse-free survival (RFS; P = .8112), with 2-year RFS for the high-risk group of 63% (95% confidence interval [CI], 52-77). There was similarly no difference seen in overall survival (OS) (P = .5488), with 2-year OS for the high-risk group of 70% (95% CI, 60-82). For patients with KMT2A-rearranged infant ALL (n = 13), 2-year RFS was 67% (95% CI, 45-99), and OS was 62% (95% CI, 40-95), with multivariable analysis demonstrating no increased risk of relapse (hazard ratio, 0.70; 95% CI, 0.21-2.90; P = .7040) but a higher proportion of relapses associated with myeloid lineage switch and a 3.6-fold increased risk of all-cause death (95% CI, 1.04-12.75; P = .0434). CTL019/huCART19/tisagenlecleucel are effective at achieving durable remissions across cytogenetic categories. Relapsed/refractory patients with high-risk cytogenetics, including KMT2A-rearranged infant ALL, demonstrated high RFS and OS probabilities at 2 years.

Hematopoietic stem cell transplant in two pediatric patients testing positive for SARS-CoV-2: A case report

BACKGROUND

The SARS-CoV-2 pandemic brought challenges to all areas of medicine. In pediatric bone marrow transplant (BMT), one of the biggest challenges was determining how and when to transplant patients infected with SARS-CoV-2 while mitigating the risks of COVID-related complications.

METHODS

Our joint adult and pediatric BMT program developed protocols for performing BMT during the pandemic, including guidelines for screening and isolation. For patients who tested positive for SARS-CoV-2, the general recommendation was to delay BMT for at least 14 days from the start of infection and until symptoms improved and the patient twice tested negative by polymerase chain reaction (PCR). However, delaying BMT in patients with malignancy increases the risk of relapse.

RESULTS

We opted to transplant two SARS-CoV-2 persistently PCR positive patients with leukemia at high risk of relapse. One patient passed away early post-BMT of a transplant-related complication. The other patient is currently in remission and doing well.

CONCLUSION

These cases demonstrate that when the risk associated with delaying BMT is high, it may be reasonable to proceed to transplant in pediatric leukemia patients infected with SARS-CoV-2.

The Prenatal Origin of Childhood Leukemia: Potential Applications for Epidemiology and Newborn Screening

Childhood leukemias are heterogeneous diseases with widely differing incident rates worldwide. As circulating tumors, childhood acute leukemias are uniquely accessible, and their natural history has been described in greater detail than for solid tumors. For several decades, it has been apparent that most cases of childhood acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) initiate in utero. Circumstantial evidence in support of this contention includes the young age of onset and high rate of concordance among identical twins. "Backtracking" of leukemic somatic mutations, particularly gene translocations, to cord blood and dried blood spots collected during the perinatal period has provided molecular proof of prenatal leukemogenesis. Detection of a patient's leukemia translocation in easily accessible birth samples, such as dried blood spots, is straightforward with the knowledge of their idiosyncratic breakpoints. However, to translate these findings into population-based screening and leukemia prevention requires novel methods able to detect translocations at all possible breakpoints when present in a low frequency of cells. Several studies have attempted to screen for leukemic translocations, mainly the common ETV6-RUNX1 translocation, in cord blood samples from healthy children. Most studies have reported finding translocations in healthy children, but estimates of prevalence have varied widely and greatly exceed the incidence of leukemia, leading to concerns that technical artifact or contamination produced an artificially inflated estimate of translocation prevalence at birth. New generation techniques that capture the presence of these translocations at birth have the potential to vastly increase our understanding of the epidemiology of acute leukemias. For instance, if leukemic translocations are present at birth in a far higher proportion of children than eventually develop acute leukemia, what are the exposures and somatic molecular events that lead to disease? And could children with translocations present at birth be targeted for prevention of disease? These questions must be answered before large-scale newborn screening for leukemia can occur as a public health initiative. Here, we review the literature regarding backtracking of acute leukemias and the prevalence of leukemic translocations at birth. We further suggest an agenda for epidemiologic research using new tools for population screening of leukemic translocations.

Blinatumomab following haematopoietic stem cell transplantation - a novel approach for the treatment of acute lymphoblastic leukaemia in infants

Blinatumomab with subsequent haematopoietic stem cell transplantation was applied in 13 infants with acute lymphoblastic leukaemia (ALL). Eight patients were treated in first remission due to slow clearance of minimal residual disease (MRD); one for MRD-reappearance after long MRD negativity, one for primary refractory disease and three during relapse treatment. In slow MRD responders, complete MRD response was achieved prior to transplantation, with an 18-month event-free survival of 75%. In contrast, only one of five patients with relapsed/refractory ALL is still in complete remission. These data provide a basis for future studies of immunotherapy in very high-risk infant ALL.

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

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

Chimeric antigen receptor T-cell therapy for marrow and extramedullary relapse of infant acute lymphoblastic leukemia

Chimeric antigen receptor (CAR) T-cells, engineered autologous T-cells that target antigens found in leukemia, have shown durable remissions in relapsed acute lymphoblastic leukemia (ALL). Infant ALL with KMT2A rearrangements (KMT2Ar) is a rare, aggressive form of leukemia associated with extramedullary disease both at diagnosis and at relapse, and overall outcomes for these patients are dismal. Here we report the successful use of tisagenlecleucel, a CAR T-cell product approved for relapsed/refractory ALL, in a patient with KMT2Ar infant ALL who was treated for combined marrow and extramedullary (renal) relapse.

No benefit of Interfant protocols compared to BFM-based protocols for infants with acute lymphoblastic leukemia. Results from an institution in Argentina

BACKGROUND

Infant acute lymphoblastic leukemia (ALL) is an infrequent disease characterized by clinical and biological features related to poor prognosis. Adapted therapies were designed without a clear consensus regarding the best treatment options. We aimed to compare the outcome between infant ALL cases receiving Interfant versus BFM-based protocols.

PROCEDURE

This is a retrospective observational study. From April 1990 to June 2018, infant ALL cases were enrolled in one of the five consecutive treatment protocols. Clinical, demographic, and biological features and outcome were evaluated. A comparative analysis was performed between Interfant protocols and BFM-based protocols.

RESULTS

During the studied period, 1913 ALL patients were admitted and 116 (6%) were infants. Treatment administered was: ALL-BFM'90 (n = 16), 1-ALL96-BFM/HPG (n = 7), Interfant-99 (n = 39), Interfant-06 (n = 35), and ALLIC-BFM'2009 (n = 19). The 5-year event-free survival probability (EFSp) was 31.9(standard error [SE] 4.6)% for the entire population, with a significant difference among risk groups according to Interfant-06 criteria (P = .0029). KMT2A-rearrangement status was the strongest prognostic factor (P = .048), independently of the protocol strategy. The median time for relapse was 24.1 months for patients with minimal residual disease (MRD)-negative versus 11.5 months for those with MRD-positive (P = .0386). EFSp and cumulative relapse risk probability (CRRp) were similar. Interfant protocols showed comparable induction (8.1% vs 7.1%, P = .852) and complete remission mortality (21.6% vs 28.6%, P = .438), failing to reduce the relapse rate (48.5% vs 30.7%, P = .149).

CONCLUSIONS

Interfant protocols and BFM-based protocols presented comparable results. The risk group stratification proposed by Interfant-06 was validated by our results, and MRD seems useful to identify patients with an increased risk of early relapse.

Evidence-based review of genomic aberrations in B-lymphoblastic leukemia/lymphoma: Report from the cancer genomics consortium working group for lymphoblastic leukemia

Clinical management and risk stratification of B-lymphoblastic leukemia/ lymphoma (B-ALL/LBL) depend largely on identification of chromosomal abnormalities obtained using conventional cytogenetics and Fluorescence In Situ Hybridization (FISH) testing. In the last few decades, testing algorithms have been implemented to support an optimal risk-oriented therapy, leading to a large improvement in overall survival. In addition, large scale genomic studies have identified multiple aberrations of prognostic significance that are not routinely tested by existing modalities. However, as chromosomal microarray analysis (CMA) and next-generation sequencing (NGS) technologies are increasingly used in clinical management of hematologic malignancies, these abnormalities may be more readily detected. In this article, we have compiled a comprehensive, evidence-based review of the current B-ALL literature, focusing on known and published subtypes described to date. More specifically, we describe the role of various testing modalities in the diagnosis, prognosis, and therapeutic relevance. In addition, we propose a testing algorithm aimed at assisting laboratories in the most effective detection of the underlying genomic abnormalities.

Myeloablative conditioning for allo-HSCT in pediatric ALL: FTBI or chemotherapy?-A multicenter EBMT-PDWP study

Although most children with acute lymphoblastic leukemia (ALL) receive fractionated total body irradiation (FTBI) as myeloablative conditioning (MAC) for allogeneic hematopoietic stem cell transplantation (allo-HSCT), it is an important matter of debate if chemotherapy can effectively replace FTBI. To compare outcomes after FTBI versus chemotherapy-based conditioning (CC), we performed a retrospective EBMT registry study. Children aged 2–18 years after MAC for first allo-HSCT of bone marrow (BM) or peripheral blood stem cells (PBSC) from matched-related (MRD) or unrelated donors (UD) in first (CR1) or second remission (CR2) between 2000 and 2012 were included. Propensity score weighting was used to control pretreatment imbalances of the observed variables. 3.054 patients were analyzed. CR1 (1.498): median follow-up (FU) after FTBI (1.285) and CC (213) was 6.8 and 6.1 years. Survivals were not significantly different. CR2 (1.556): median FU after FTBI (1.345) and CC (211) was 6.2 years. Outcomes after FTBI were superior as compared with CC with regard to overall survival (OS), leukemia-free survival (LFS), relapse incidence (RI), and nonrelapse mortality (NRM). However, we must emphasize the preliminary character of the results of this retrospective “real-world-practice” study. These findings will be prospectively assessed in the ALL SCTped 2012 FORUM trial.

CD19 CAR T Cells for the Treatment of Pediatric Pre-B Cell Acute Lymphoblastic Leukemia

The development of cluster of differentiation (CD)-19-targeted chimeric antigen receptor (CAR) T cells for the treatment of pre-B-cell acute lymphoblastic leukemia (B-ALL) is an exciting new advancement in the field of pediatric oncology. Tisagenlecleucel and axicabtagene ciloleucel are the first US FDA-approved CD19-targeted CAR T cells. While various different CD19 CAR T cells are in development, tisagenlecleucel is the only CAR T cell approved for pediatric patients. The multicenter phase II trial that led to the approval of tisagenlecleucel demonstrated excellent responses in individuals with highly refractory disease. Other high-risk groups of patients with B-ALL who experience poor outcomes with standard therapy may also benefit from treatment with tisagenlecleucel. After receiving CAR T cells, patients must be closely monitored for unique toxicities, including cytokine release syndrome, neurotoxicity, and B-cell aplasia. The management of patients with relapsed or refractory disease after administration of CD19 CAR T cells can be challenging, and treatment options vary according to the characteristics of the disease present at relapse. In the many patients who experience a complete response, CAR T cells can lead to a durable remission. This review describes the current design and manufacturing of CAR T cells. Data in the selection and management of pediatric patients are highlighted, as are areas where further studies are needed.

Outcome of Infants Younger Than 1 Year With Acute Lymphoblastic Leukemia Treated With the Interfant-06 Protocol: Results From an International Phase III Randomized Study

PURPOSE

Infant acute lymphoblastic leukemia (ALL) is characterized by KMT2A (MLL) gene rearrangements and coexpression of myeloid markers. The Interfant-06 study, comprising 18 national and international study groups, tested whether myeloid-style consolidation chemotherapy is superior to lymphoid style, the role of stem-cell transplantation (SCT), and which factors had independent prognostic value.

MATERIALS AND METHODS

Three risk groups were defined: low risk (LR): KMT2A germline; high risk (HR): KMT2A-rearranged and older than 6 months with WBC count 300 × 10⁹/L or more or a poor prednisone response; and medium risk (MR): all other KMT2A-rearranged cases. Patients in the MR and HR groups were randomly assigned to receive the lymphoid course low-dose cytosine arabinoside [araC], 6-mercaptopurine, cyclophosphamide (IB) or experimental myeloid courses, namely araC, daunorubicin, etoposide (ADE) and mitoxantrone, araC, etoposide (MAE).

RESULTS

A total of 651 infants were included, with 6-year event-free survival (EFS) and overall survival of 46.1% (SE, 2.1) and 58.2% (SE, 2.0). In West European/North American groups, 6-year EFS and overall survival were 49.4% (SE, 2.5) and 62.1% (SE, 2.4), which were 10% to 12% higher than in other countries. The 6-year probability of disease-free survival was comparable for the randomized arms (ADE+MAE 39.3% [SE 4.0; n = 169] v IB 36.8% [SE, 3.9; n = 161]; log-rank P = .47). The 6-year EFS rate of patients in the HR group was 20.9% (SE, 3.4) with the intention to undergo SCT; only 46% of them received SCT, because many had early events. KMT2A rearrangement was the strongest prognostic factor for EFS, followed by age, WBC count, and prednisone response.

CONCLUSION

Early intensification with postinduction myeloid-type chemotherapy courses did not significantly improve outcome for infant ALL compared with the lymphoid-type course IB. Outcome for infant ALL in Interfant-06 did not improve compared with that in Interfant-99.

Spontaneous reversion of a lineage switch following an initial blinatumomab-induced ALL-to-AML switch in MLL-rearranged infant ALL

A case of MLL-rearranged leukemia that rapidly adapts to immunological stimuli illustrating the high plasticity of this phenotype.

A novel small molecule that kills a subset of MLL-rearranged leukemia cells by inducing mitochondrial dysfunction

Survival rates for pediatric patients suffering from mixed lineage leukemia (MLL)-rearranged leukemia remain below 50% and more targeted, less toxic therapies are urgently needed. A screening method optimized to discover cytotoxic compounds selective for MLL-rearranged leukemia identified CCI-006 as a novel inhibitor of MLL-rearranged and CALM-AF10 translocated leukemias that share common leukemogenic pathways. CCI-006 inhibited mitochondrial respiration and induced mitochondrial membrane depolarization and apoptosis in a subset (7/11, 64%) of MLL-rearranged leukemia cell lines within a few hours of treatment. The unresponsive MLL-rearranged leukemia cells did not undergo mitochondrial membrane depolarization or apoptosis despite a similar attenuation of mitochondrial respiration by the compound. In comparison to the sensitive cells, the unresponsive MLL-rearranged leukemia cells were characterized by a more glycolytic metabolic phenotype, exemplified by a more pronounced sensitivity to glycolysis inhibitors and elevated HIF1α expression. Silencing of HIF1α expression sensitized an intrinsically unresponsive MLL-rearranged leukemia cell to CCI-006, indicating that this pathway plays a role in determining sensitivity to the compound. In addition, unresponsive MLL-rearranged leukemia cells expressed increased levels of MEIS1, an important leukemogenic MLL target gene that plays a role in regulating metabolic phenotype through HIF1α. MEIS1 expression was also variable in a pediatric MLL-rearranged ALL patient dataset, highlighting the existence of a previously undescribed metabolic variability in MLL-rearranged leukemia that may contribute to the heterogeneity of the disease. This study thus identified a novel small molecule that rapidly kills MLL-rearranged leukemia cells by targeting a metabolic vulnerability in a subset of low HIF1α/low MEIS1-expressing MLL-rearranged leukemia cells.

How I treat infant leukemia

Leukemia in infants is rare but generates tremendous interest due to its aggressive clinical presentation in a uniquely vulnerable host, its poor response to current therapies, and its fascinating biology. Increasingly, these biological insights are pointing the way toward novel therapeutic approaches. Using representative clinical case presentations, we review the key clinical, pathologic, and epidemiologic features of infant leukemia, including the high frequency of KMT2A gene rearrangements. We describe the current approach to risk-stratified treatment of infant leukemia in the major international cooperative groups. We highlight recent discoveries that elucidate the molecular biology of infant leukemia and suggest novel targeted therapeutic strategies, including modulation of aberrant epigenetic programs, inhibition of signaling pathways, and immunotherapeutics. Finally, we underscore the need for increased global collaboration to translate these discoveries into improved outcomes.

Azacitidine successfully maintained the second remission in an infant with KMT2A-rearranged acute lymphoblastic leukemia who relapsed after unrelated cord blood transplantation

The outcome for infants with KMT2A (MLL)-rearranged acute lymphoblastic leukemia (MLL-r ALL) is dismal despite intensive therapy, including hematopoietic stem cell transplantation (HSCT). Epigenetic dysregulation is considered a key driver of MLL-r leukemogenesis, which theoretically supports the use of epigenetic modifiers as a treatment option. We report an infant MLL-r ALL case with post-HSCT relapse. After achieving a second remission, which was maintained for 10 months using only the DNA methyltransferase inhibitor, azacitidine, the patient successfully received the second HSCT. This report describes the clinical effectiveness of azacitidine for the treatment of infant MLL-r ALL.

Updates in the biology and therapy for infant acute lymphoblastic leukemia

PURPOSE OF REVIEW

The prognosis for infants less than 12 months of age who are diagnosed with acute lymphoblastic leukemia (ALL) remains poor despite overall advances in the treatment of childhood ALL. In this review, we highlight the recent advances in the understanding of the pathogenesis of infant ALL and discuss opportunities for translating these findings into clinical trials.

RECENT FINDINGS

Infant ALL can be divided into two major disease types, defined by the presence or absence of KMT2A (MLL) rearrangement (KMT2A-R). Recent molecular profiling studies have found that infant ALL with KMT2A-R is an epigenomic disease that lacks other somatic driver mutations. Strategies to intensify therapy have not improved survival for infants with KMT2A-R ALL. In contrast, infant ALL without KMT2A-R is more similar to ALL of older children and survival has improved modestly with intensification of chemotherapy. Discovery of clonal molecular markers that predict chemoresistance will allow further risk classification and development of novel treatment strategies. Modern clinical trials are integrating molecularly targeted therapies into the treatment of infant ALL.

SUMMARY

Advances in molecular profiling and integration of targeted therapy have the potential to reduce toxicity and improve survival for infants with ALL.

Discovery of Novel Inhibitors Targeting the Menin-Mixed Lineage Leukemia Interface Using Pharmacophore- and Docking-Based Virtual Screening

Disrupting the interaction between mixed lineage leukemia (MLL) fusion protein and menin provides a therapeutic approach for MLL-mediated leukemia. Here, we aim to discover novel inhibitors targeting the menin-MLL interface with virtual screening. Both structure-based molecular docking and ligand-based pharmacophore models were established, and the models used for compound screening show a remarkable ability to retrieve known active ligands from decoy molecules. Verified by a fluorescence polarization assay, five hits with novel scaffolds were identified. Among them, DCZ_M123 exhibited potent inhibitory activity with an IC50 of 4.71 ± 0.12 μM and a KD of 14.70 ± 2.13 μM, and it can effectively inhibit the human MLL-rearranged leukemia cells MV4;11 and KOPN8 with GI50 values of 0.84 μM and 0.54 μM, respectively.