Effect of Dasatinib vs Imatinib in the Treatment of Pediatric Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia: A Randomized Clinical Trial

Mild blurry vision as the initial presentation of central nervous system relapses of acute lymphoblastic leukemia: a case report

BACKGROUND

Leukemia relapses after hematopoietic stem cell transplantation can sometimes occur from the central nervous system prior to relapse from the bone marrow, and manifestations varied.

CASE REPORT

We present a case of mild blurry vision as the initial symptom of central nervous system relapse of adult acute lymphoblastic leukemia. A 30-year-old man presented with a 1 week history of painless visual loss in both eyes. At that time there were no headaches or other systemic features. The neurological examination was without positive findings except bilateral optic nerve edema. He had a history of acute lymphoblastic leukemia and hematopoietic stem cell transplantation, which had been in clinical remission post-transplant for 1 year. Lumbar puncture revealed relapsed disease within the central nervous system, confirmed with cerebrospinal fluid leukemic blasts.

CONCLUSIONS

It highlights the need for ophthalmologists to be aware of the possibility of central nervous system involvement in patients with the setting of leukemia when visual symptoms as the initial manifestation.

Ph+ ALL in 2022: is there an optimal approach?

Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) carried a very poor prognosis prior to the advent of tyrosine kinase inhibitors (TKIs) that block the activity of the BCR-ABL1 oncoprotein. With improvements in TKI efficacy and allogeneic hematopoietic cell transplantation (HCT), survival has improved over the past 3 decades, and the role of chemotherapy and allogeneic HCT is now changing. Better risk stratification, the application of the third-generation TKI ponatinib, and the use of immunotherapy with the CD19-CD3 bifunctional T-cell engaging antibody blinatumomab in place of chemotherapy has made therapy for Ph+ ALL more tolerable and arguably more efficacious, especially for older patients who comprise most patients with Ph+ ALL.

Evidence-Based Minireview: What is the optimal tyrosine kinase inhibitor for adults with newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia?

The incorporation of BCR::ABL1 tyrosine kinase inhibitors (TKIs) to intensive chemotherapy significantly improved the outcomes of patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). This was first shown with the addition of the first-generation TKI imatinib, which allowed more patients to be bridged to an allogeneic stem cell transplant (SCT) and led to superior long-term outcomes compared with chemotherapy alone. The use of second-generation TKIs (eg, dasatinib and nilotinib) has led to further improvement in outcomes of patients with Ph- positive ALL, with a long-term survival of 40% to 60% in several studies. Ponatinib is a third-generation, more potent TKI that results in high rates of molecular response and promising long-term survival even when allogeneic SCT is not routinely performed. While randomized data to support the TKI selection in Ph-positive ALL are lacking, data from single-arm studies suggest deeper molecular responses and superior survival outcomes with each successive generation of TKI. More recently, chemotherapy-free regimens with blinatumomab and TKIs have shown excellent results in the frontline setting and may represent an emerging paradigm shift in the treatment of Ph-positive ALL.

A Historical Misconception in Clinical Trials of Drugs for Cancer-Age Grouping

In clinical trials of cancer drugs, grouping by age is a very common grouping method, as it can allow for a visual comparison of the different pharmaceutical responses in patients at different age stages. Under the guidance of this thinking, many researchers use age grouping when studying clinical cancer drugs. However, even people at the same age may be at different stages in their lives, such as individuals who are going through puberty, menopause/andropause, or intermediate transition, as well as childhood and old age, affected by factors such as hormone levels, immune responses, ethnic groups, and regions. Every individual has different cancer symptoms and responses to drugs; therefore, the experimental effect of life stage grouping will be more obvious and clearer. Not only does this conclusion apply to cancer drugs, but it also applies to clinical trials for other diseases. In addition, this does not mean that age grouping should be completely abandoned. Life stage is a more general interval that can be further divided into life stage groups according to the age of the patients. Based on the principal law of lifespan (PLOSP), age trends in life stages also need to be updated from time to time. To date, life stage grouping has not been discussed systematically and has not been used as a grouping method for cancer patients. In this paper, life stage grouping is discussed as one of the important grouping categories in cancer clinical trials.

Central nervous system involvement in childhood acute lymphoblastic leukemia: challenges and solutions

Delivery of effective anti-leukemic agents to the central nervous system (CNS) is considered essential for cure of childhood acute lymphoblastic leukemia. Current CNS-directed therapy comprises systemic therapy with good CNS-penetration accompanied by repeated intrathecal treatments up to 26 times over 2-3 years. This approach prevents most CNS relapses, but is associated with significant short and long term neurotoxicity. Despite this burdensome therapy, there have been no new drugs licensed for CNS-leukemia since the 1960s, when very limited anti-leukemic agents were available and there was no mechanistic understanding of leukemia survival in the CNS. Another major barrier to improved treatment is that we cannot accurately identify children at risk of CNS relapse, or monitor response to treatment, due to a lack of sensitive biomarkers. A paradigm shift in treating the CNS is needed. The challenges are clear - we cannot measure CNS leukemic load, trials have been unable to establish the most effective CNS treatment regimens, and non-toxic approaches for relapsed, refractory, or intolerant patients are lacking. In this review we discuss these challenges and highlight research advances aiming to provide solutions. Unlocking the potential of risk-adapted non-toxic CNS-directed therapy requires; (1) discovery of robust diagnostic, prognostic and response biomarkers for CNS-leukemia, (2) identification of novel therapeutic targets combined with associated investment in drug development and early-phase trials and (3) engineering of immunotherapies to overcome the unique challenges of the CNS microenvironment. Fortunately, research into CNS-ALL is now making progress in addressing these unmet needs: biomarkers, such as CSF-flow cytometry, are now being tested in prospective trials, novel drugs are being tested in Phase I/II trials, and immunotherapies are increasingly available to patients with CNS relapses. The future is hopeful for improved management of the CNS over the next decade.

Tyrosine kinase inhibitors and reduced-dose chemotherapy for adult Philadelphia chromosome-positive acute lymphoblastic leukemia

Objectives: To compare the outcomes of tyrosine kinase inhibitors (TKIs) in combination with reduced-dose chemotherapy with those of standard induction chemotherapy, as well as the outcomes between chemotherapy and transplantation, in adults with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL).Methods: We retrospectively reviewed cases of Ph+ ALL treated with TKIs and combination chemotherapy. The patients were allocated to either the TKIs with reduced-dose chemotherapy group or the TKIs with standard chemotherapy group. In additions, patients were further stratified into either the transplant group or the non-transplant group.Results: The complete remission rate (88.7% vs. 83.9%, p = 0.372), major molecular response (58.9% vs. 56.0%, p = 0.750), molecular complete response (20.5% vs. 22.0%, p = 0.891), and early mortality rate (3.2% vs. 3.5%, p = 0.922) were similar between the TKIs with reduced-dose chemotherapy group and the TKIs with standard chemotherapy group. The proportions of lung infections, bloodstream infections, patients with >21 days of hospitalization, the total costs, transfusion costs, and antimicrobial costs were higher in the standard chemotherapy group than in the TKIs with reduced-dose chemotherapy group. The 3-year overall survival rates (59.0% [95% CI, 46.6-74.7%] vs. 38.4% [95% CI, 29.9-49.4%]) and disease-free survival rates (48.6% [95% CI, 34.2-69.1%] vs. 32.0% [95% CI, 23.5-43.7%]) were significantly better in the transplant group than in the non-transplant group.Conclusion: An induction regimen combining TKIs with reduced-dose chemotherapy and transplantation during the first complete remission remains a suitable and effective option for patients with Ph+ ALL.

The role of allogeneic transplant for adult Ph+ ALL in CR1 with complete molecular remission: a retrospective analysis

Historically, Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with poor outcomes, and allogeneic hematopoietic cell transplantation (allo-HCT) is recommended in first complete remission (CR1). However, in the tyrosine kinase inhibitor (TKI) era, rapid attainment of a complete molecular remission (CMR) is associated with excellent outcomes without allo-HCT, suggesting transplant may not be required for these patients. To test this hypothesis, we retrospectively identified adult patients with Ph+ ALL treated with induction therapy, including TKIs, and attained CMR within 90 days of diagnosis at 5 transplant centers in the United States. We compared outcomes of those who did and did not receive allo-HCT in first remission. We identified 230 patients (allo-HCT: 98; non-HCT: 132). The allo-HCT cohort was younger with better performance status. On multivariable analysis (MVA), allo-HCT was not associated with improved overall survival (adjusted hazard ratio [aHR]: 1.05; 95% CI, 0.63-1.73) or relapse-free survival (aHR: 0.86; 95% CI, 0.54-1.37) compared with non-HCT treatment. Allo-HCT was associated with a lower cumulative incidence of relapse (aHR: 0.32; 95% CI, 0.17-0.62) but higher non-relapse mortality (aHR: 2.59; 95% CI, 1.37-4.89). Propensity score matching analysis confirmed results of MVA. Comparison of reduced-intensity HCT to non-HCT showed no statistically significant difference in any of the above endpoints. In conclusion, adult patients with Ph+ ALL who achieved CMR within 90 days of starting treatment did not derive a survival benefit from allo-HCT in CR1 in this retrospective study.

Infectious Complications of Targeted Therapies in Children with Leukemias and Lymphomas

Simple Summary

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

Abstract

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

An integrated microfluidics platform with high-throughput single-cell cloning array and concentration gradient generator for efficient cancer drug effect screening

BACKGROUND

Tumor cell heterogeneity mediated drug resistance has been recognized as the stumbling block of cancer treatment. Elucidating the cytotoxicity of anticancer drugs at single-cell level in a high-throughput way is thus of great value for developing precision therapy. However, current techniques suffer from limitations in dynamically characterizing the responses of thousands of single cells or cell clones presented to multiple drug conditions.

METHODS

We developed a new microfluidics-based "SMART" platform that is Simple to operate, able to generate a Massive single-cell array and Multiplex drug concentrations, capable of keeping cells Alive, Retainable and Trackable in the microchambers. These features are achieved by integrating a Microfluidic chamber Array (4320 units) and a six-Concentration gradient generator (MAC), which enables highly efficient analysis of leukemia drug effects on single cells and cell clones in a high-throughput way.

RESULTS

A simple procedure produces 6 on-chip drug gradients to treat more than 3000 single cells or single-cell derived clones and thus allows an efficient and precise analysis of cell heterogeneity. The statistic results reveal that Imatinib (Ima) and Resveratrol (Res) combination treatment on single cells or clones is much more efficient than Ima or Res single drug treatment, indicated by the markedly reduced half maximal inhibitory concentration (IC₅₀). Additionally, single-cell derived clones demonstrate a higher IC₅₀ in each drug treatment compared to single cells. Moreover, primary cells isolated from two leukemia patients are also found with apparent heterogeneity upon drug treatment on MAC.

CONCLUSION

This microfluidics-based "SMART" platform allows high-throughput single-cell capture and culture, dynamic drug-gradient treatment and cell response monitoring, which represents a new approach to efficiently investigate anticancer drug effects and should benefit drug discovery for leukemia and other cancers.

Modern Management Options for Ph+ ALL

Simple Summary

The use of tyrosine kinase inhibitors has represented a major step forward in the therapy of Philadelphia chromosome positive acute lymphoblastic leukemia. Recent improvements in the therapy are focused on early use of third generation tyrosine kinase inhibitors, their combination with immunotherapy, the refined indication of allogeneic hematopoietic stem cell transplantation, the optimal use and duration of maintenance therapy, and the management of patients with molecular or hematological relapse with combination of targeted therapies and immunotherapy, including cellular therapies. Improvements in the assessment of measurable residual disease and in the detection of mutations in the ABL1 domain are contributing to the better selection of the therapy for newly diagnosed as well as for relapsed or refractory patients.

Abstract

Impressive advances have been achieved in the management of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) since the initial concurrent use of imatinib and standard chemotherapy. The attenuation of chemotherapy has proven to be equally effective and less toxic, the use of third generation TKI upfront has improved the frequency of complete molecular response and the survival rate, and the combination of tyrosine kinase inhibitors with immunotherapy has further increased the rate of molecular response to 70–80% after consolidation, which has been translated into a survival rate of 75–90% in recent trials. As a result of these improvements, the role of allogeneic hematopoietic stem cell transplantation is being redefined. The methodology of measurable residual disease assessment and the detection of ABL1 mutations are also improving and will contribute to a more precise selection of the treatment for newly diagnosed and relapsed or refractory (R/R) patients. Finally, new compounds combined with immunotherapeutic approaches, including cellular therapy, are being used as rescue therapy and will hopefully be included in first line therapy in the near future. This article will review and update the modern management of patients with Ph+ ALL.

Distribution and frequency of tyrosine kinase inhibitor-associated long-term complications in children with chronic myeloid leukemia

BACKGROUND

Tyrosine kinase inhibitors (TKIs) improve outcomes for pediatric malignancies characterized by specific gene rearrangements and mutations; however, little is known about the long-term impact of TKI exposure. Our objective was to assess the incidence and type of late-onset TKI-related toxicities in children with chronic myeloid leukemia (CML).

METHODS

We reviewed medical records from patients diagnosed with CML between 2006 and 2019 at <21 years of age and prescribed one or more TKIs. Patients treated with stem cell transplant were excluded. Outcomes were captured beginning at 1 year after CML diagnosis. Outcome incidence was described overall and stratified by TKI exposure during the data-capture period.

RESULTS

Twenty-two eligible TKI-exposed patients with CML were identified. The median follow-up was 6.0 years (range: 2.2-14.3). All pericardial (n = 3) or pleural (n = 3) effusion outcomes occurred in patients treated with TKIs during the data-capture period. Other outcomes included hypertension (n = 2), ectopy on electrocardiogram (n = 2), and gastrointestinal bleed (n = 1). All outcomes were graded as mild to moderate: some resulted in a temporary discontinuation of TKI, but none led to a change in TKI. No differences were noted in outcome incidence by type of TKI exposure.

CONCLUSIONS

TKIs have substantially improved prognosis for subsets of childhood leukemia, but there are limited long-term data to inform exposure-based risk for late-onset complications and screening. Our results suggest that TKI-exposed survivors may be at risk for long-term outcomes that extend well into survivorship.

Dasatinib-therapy induced sustained remission in a child with refractory TCF7-SPI1 T-cell acute lymphoblastic leukemia

The prognosis of patients with T-cell acute lymphoblastic leukemia (T-ALL) has been largely lacked behind than that of patients with B-cell ALL, especially in refractory or relapsed cases. Here, we describe a 4.7-year-old male child with TCF-SPI1-postitve T-ALL who developed refractoriness disease after a seven drugs-conventional therapy. Several studies have suggested the therapeutic potential of dasatinib in refractory T-ALL. Actually, dasatinib-included therapy dramatically reduces the leukemic burden and re-induces this patient into complete remission without systemic adverse events. Although this is a single exceptional case, the translational potential evidence of dasatinib in specific T-ALL subtype should not be under-estimated.

Treatment of Adults With Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia-From Intensive Chemotherapy Combinations to Chemotherapy-Free Regimens: A Review

Importance

With the advent of potent BCR::ABL1 tyrosine kinase inhibitors (TKIs), Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) is now a relatively favorable-risk acute leukemia. In this review, we discuss the current evidence for frontline therapies of Ph-positive ALL, the major principles that guide therapy, and the progress with chemotherapy-free regimens.

Observations

Incorporating TKIs into the chemotherapy regimens of patients with newly diagnosed Ph-positive ALL has led to improved remission rates, higher probability of reaching allogeneic stem cell transplantation (SCT), and longer survival compared with chemotherapy alone. Early achievement of a complete molecular remission (CMR) is an important end point in Ph-positive ALL and identifies patients who have excellent long-term survival and may not need allogeneic SCT. Second-generation TKIs combined with intensive or low-intensity chemotherapy resulted in higher CMR rates compared with imatinib-based regimens. This translated into better outcomes, with less reliance on allogeneic SCT. To further improve the outcomes, the potent third-generation TKI ponatinib was added to chemotherapy. The combination of hyper-CVAD and ponatinib resulted in an overall CMR rate of 84% and a 5-year survival rate of 73% and 86% among patients who did and did not undergo allogeneic SCT, respectively, suggesting that allogeneic SCT may not be needed with this regimen. The recent chemotherapy-free combination of dasatinib and blinatumomab was safe and effective in patients with newly diagnosed Ph-positive ALL and resulted in an estimated 3-year OS rate of 80%; 50% of patients underwent allogeneic SCT. The chemotherapy-free regimen of ponatinib and blinatumomab resulted in a CMR rate of 86% and a 2-year survival rate of 93%, with no relapses or leukemia-related deaths, and with only 1 patient proceeding to allogeneic SCT.

Conclusions and Relevance

The promising results obtained with the chemotherapy-free regimens of blinatumomab plus TKIs question the role of allogeneic SCT in first remission. Patients with Ph-positive ALL who achieve early and deep molecular responses have excellent long-term outcomes and may not benefit from allogeneic SCT.

Childhood Acute B-Lineage Lymphoblastic Leukemia With CDKN2A/B Deletion Is a Distinct Entity With Adverse Genetic Features and Poor Clinical Outcomes

To further emphasize the clinical-genetic features and prognosis of CDKN2A/B deletions in childhood acute lymphoblastic leukemia (ALL), we retrospectively analyzed 819 consecutive B-ALL patients treated with the Chinese Children's Cancer Group ALL-2015 (CCCG-ALL-2015) protocol, and fluorescence in situ hybridization (FISH) analysis on CDKN2A/B deletion was available for 599 patients. The prevalence of CDKN2A/B gene deletions was 20.2% (121/599) of B-ALL. CDKN2A/B deletions were significantly associated with older age, higher leukocyte counts, a higher percentage of hepatosplenomegaly, and a higher frequency of BCR-ABL (p < 0.05). Those patients achieved similar minimal residual disease (MRD) clearance and complete remission compared to patients without CDKN2A/B deletion. The CDKN2A/B deletions were correlated with inferior outcomes, including a 3-year event-free survival (EFS) rate (69.8 ± 4.6 vs. 89.2 ± 1.6%, p = 0.000) and a 3-year overall survival (OS) rate (89.4% ± 2.9% vs. 94.7% ± 1.1%, p = 0.037). In multivariable analysis, CDKN2A/B deletion was still an independent prognostic factor for EFS in total cohorts (p < 0.05). We also detected a multiplicative interaction between CDKN2A/B deletions and TP53 deletion on dismal prognosis (p-interaction < 0.05). In conclusion, CDKN2A/B deletion is associated with distinct characteristics and serves as a poor prognostic factor in pediatric ALL, especially in TP53 deletion carriers.

Reduced Dose Intensity of Daunorubicin During Remission Induction for Low-Risk Patients With Acute Lymphoblastic Leukemia: A Retrospective Cohort Study of the Chinese Children’s Cancer Group

It is urgently necessary to reduce the adverse effects of chemotherapy while maintaining their cure high rates for children with acute lymphoblastic leukemia (ALL). The present study aimed to determine whether the dose intensity of daunorubicin during the remission-induction phase could be reduced for low-risk patients with ALL. A total of 2396 eligible patients, who participated in CCCG-ALL-2015 study and were provisionally assigned to the low-risk group, were included and divided into single-dose group and double-dose group according to the dosage of daunorubicin during the remission-induction phase. For patients with ETV6-RUNX1 positive ALL or hyperdiploidy ALL, there were no significant differences in outcomes between the two groups. For other patients, the 5-year event-free survival rate was significantly better and the 5-year cumulative risk of any relapse was significantly lower in the double-dose group compared with the single-dose group. Both the 5-year overall survival rate and the risk of early deaths were not significantly different between the two groups. Our results suggested that only B-lineage ALL patients with ETV6-RUNX1 positivity or hyperdiploidy who achieved an early negative minimal residual disease status were suitable candidates for dosage reduction of daunorubicin during the remission-induction phase.

Somatic FOXC1 insertion mutation remodels the immune microenvironment and promotes the progression of childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common malignant hematological diseases in children. An immunosuppressive microenvironment, particularly regulatory T cell (Treg) infiltration, has been documented to be highly associated with childhood ALL. This present study, based on genetic factors, was aimed at investigating the mutations potentially involved in the immunosuppressive microenvironment in childhood ALL. After whole-exome sequencing was used on DNA extracted from the T cells of ALL bone marrow samples, we found the FOXC1 H446HG induced a increased Treg while decreased cytotoxic T lymphocyte (CTL) in bone marrow. The mutation of FOXC1 in T cell promoted the proliferation of leukemia cells in vitro and in vivo. CpG islands formed by insertion mutation led to an abnormal increase in exon methylation and were associated with the suppression of FOXC1. Decreased FOXC1 attenuated the transcription of HDAC1, thus resulting in the activation of KLF10 through increasing H3K27 acetylation in the promoter region. In conclusion, the de novo insertion mutation in FOXC1 induced suppression of FOXC1, thereby promoting a Treg/CTL shift in the ALL immune microenvironment. The FOXC1 H446HG mutation might be a potential therapeutic target for ALL in the future.

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.

Primary Testicular and Cutaneous Philadelphia Chromosome Positive B-Cell Lymphoblastic Lymphoma: A Rare Case and Review

Philadelphia chromosome positive B cell lymphoblastic lymphoma (Ph+ B-LBL) is an extremely rare disease. We report a 27-year-old patient diagnosed with primary testicular and cutaneous Ph+ B-LBL without bone marrow involvement. The CCCG-LBL-2016 regimen (https://clinicaltrials.gov/ct2/show/NCT02845882) was initially administered due to the fast pathological diagnosis as B-LBL that was first obtained. To identify potential therapeutic targets, RNA sequencing (RNAseq) was also performed on lymph node specimens as a part of the routine diagnostic workup in our center. Unexpectedly, IKZF1 deletions and BCR-ABL1 fusion transcripts were detected. Based on these results, we retrospectively performed fluorescence in situ hybridization (FISH) for BCR/ABL1 rearrangements in the same lymph node specimen, and a 70% positive signal was detected. The patient subsequently received the CCCG-LBL-2016 protocol combined with the BCR-ABL tyrosine kinase inhibitor (TKI) dasatinib, along with prophylactic intrathecal infusion. Then, the patient underwent TBI-based haploidentical (haplo) allogeneic hematopoietic stem cell transplantation (haplo-allo-HSCT) as consolidation following the achievement of remission and continued taking dasatinib as maintenance therapy. The patient was still in complete remission 1 year after diagnosis. This case indicates that the detection of potential molecular targets, especially those targets that can be pharmacologically treated, such as BCR/ABL1 fusion transcripts, is of important value to both LBL diagnosis and therapeutic strategy choices. FISH, reverse transcriptase polymerase chain reaction (RT-PCR) and/or RNAseq should be routinely carried out in lymphoma specimens to depict its genetic landscape for the further execution of a precise therapy strategy.

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Dasatinib does not exacerbate dexamethasone-induced osteonecrosis in murine models of acute lymphoblastic leukemia therapy

INTRODUCTION

There are clinical reports that the incorporation of dasatinib may increase the frequency of osteonecrosis in acute lymphoblastic leukemia (ALL) treatment regimens. No rigorous testing of this hypothesis is available to guide clinicians.

METHODS

We tested whether oral dasatinib increased the frequency of dexamethasone-induced osteonecrosis in a murine model and tested its effects on dexamethasone's antileukemic efficacy in a murine BCR-ABL⁺ model of ALL.

RESULTS

Dasatinib did not change the frequency of osteonecrosis (p = .99) nor of arteriopathy (p = .36) in dexamethasone-treated mice when given at dosages that achieved clinically relevant steady-state dasatinib plasma concentrations of 53.1 ng/ml (95% CI: 43.5-57.3 ng/ml). These dasatinib exposures were not associated with increased dexamethasone plasma exposure in nonleukemia-bearing mice. These same dosages were not associated with any decrement in antileukemic efficacy of dexamethasone in a responsive BCR-ABL⁺ model of ALL.

CONCLUSIONS

Based on the results of our preclinical murine studies, we conclude that dasatinib is unlikely to increase the osteonecrotic effects of dexamethasone in ALL regimens.

Treatment of Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia in Adults

Simple Summary

Outcome of patients with Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph+ ALL) dramatically improved during the past 20 years with the advent of tyrosine kinase inhibitors and monoclonal antibodies. Their great efficacy in young and fit patients led to question our reliance on chemotherapy and allogeneic hematopoietic stem cell transplantation. Moreover, these well-tolerated treatments can be safely administrated even in the elderly that represent the majority of Ph+ ALL patient. This review will focus on the recent changes of paradigm in the management of Ph+ ALL patients and the development of novel therapeutic strategies.

Abstract

Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph+ ALL) is the most common subtype of B-ALL in adults and its incidence increases with age. It is characterized by the presence of BCR-ABL oncoprotein that plays a central role in the leukemogenesis of Ph+ ALL. Ph+ ALL patients traditionally had dismal prognosis and long-term survivors were only observed among patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR1). However, feasibility of allo-HSCT is limited in this elderly population. Fortunately, development of increasingly powerful tyrosine kinase inhibitors (TKIs) from the beginning of the 2000′s dramatically improved the prognosis of Ph+ ALL patients with complete response rates above 90%, deep molecular responses and prolonged survival, altogether with good tolerance. TKIs became the keystone of Ph+ ALL management and their great efficacy led to develop reduced-intensity chemotherapy backbones. Subsequent introduction of blinatumomab allowed going further with development of chemo free strategies. This review will focus on these amazing recent advances as well as novel therapeutic strategies in adult Ph+ ALL.

Resistance Mechanisms in Pediatric B-Cell Acute Lymphoblastic Leukemia

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

Targeting Integrins for Cancer Therapy - Disappointments and Opportunities

Integrins mediate adhesive interactions between cells and their environment, including neighboring cells and extracellular matrix (ECM). These heterodimeric transmembrane receptors bind extracellular ligands with their globular head domains and connect to the cytoskeleton through multi-protein interactions at their cytoplasmic tails. Integrin containing cell–matrix adhesions are dynamic force-responsive protein complexes that allow bidirectional mechanical coupling of cells with their environment. This allows cells to sense and modulate tissue mechanics and regulates intracellular signaling impacting on cell faith, survival, proliferation, and differentiation programs. Dysregulation of these functions has been extensively reported in cancer and associated with tumor growth, invasion, angiogenesis, metastasis, and therapy resistance. This central role in multiple hallmarks of cancer and their localization on the cell surface makes integrins attractive targets for cancer therapy. However, despite a wealth of highly encouraging preclinical data, targeting integrin adhesion complexes in clinical trials has thus far failed to meet expectations. Contributing factors to therapeutic failure are 1) variable integrin expression, 2) redundancy in integrin function, 3) distinct roles of integrins at various disease stages, and 4) sequestering of therapeutics by integrin-containing tumor-derived extracellular vesicles. Despite disappointing clinical results, new promising approaches are being investigated that highlight the potential of integrins as targets or prognostic biomarkers. Improvement of therapeutic delivery at the tumor site via integrin binding ligands is emerging as another successful approach that may enhance both efficacy and safety of conventional therapeutics. In this review we provide an overview of recent encouraging preclinical findings, we discuss the apparent disagreement between preclinical and clinical results, and we consider new opportunities to exploit the potential of integrin adhesion complexes as targets for cancer therapy.

Mapping Pediatric Oncology Clinical Trial Collaborative Groups on the Global Stage

The global pediatric oncology clinical research landscape, particularly in Central and South America, Africa, and Asia, which bear the highest burden of global childhood cancer cases, is less characterized in the literature. Review of how existing pediatric cancer clinical trial groups internationally have been formed and how their research goals have been pursued is critical for building global collaborative research and data-sharing efforts, in line with the WHO Global Initiative for Childhood Cancer.

Local stakeholder engagement is necessary to collaborate with global pediatric cancer trial groups.

Elucidating minimal residual disease of paediatric B-cell acute lymphoblastic leukaemia by single-cell analysis

Minimal residual disease that persists after chemotherapy is the most valuable prognostic marker for haematological malignancies and solid cancers. Unfortunately, our understanding of the resistance elicited in minimal residual disease is limited due to the rarity and heterogeneity of the residual cells. Here we generated 161,986 single-cell transcriptomes to analyse the dynamic changes of B-cell acute lymphoblastic leukaemia (B-ALL) at diagnosis, residual and relapse by combining single-cell RNA sequencing and B-cell-receptor sequencing. In contrast to those at diagnosis, the leukaemic cells at relapse tended to shift to poorly differentiated states, whereas the changes in the residual cells were more complicated. Differential analyses highlighted the activation of the hypoxia pathway in residual cells, resistant clones and B-ALL with MLL rearrangement. Both in vitro and in vivo models demonstrated that inhibition of the hypoxia pathway sensitized leukaemic cells to chemotherapy. This single-cell analysis of minimal residual disease opens up an avenue for the identification of potent treatment opportunities for B-ALL.

Integrated genomic analyses identify high-risk factors and actionable targets in T-cell acute lymphoblastic leukemia

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy often associated with poor outcomes. To identify high-risk factors and potential actionable targets for T-ALL, we perform integrated genomic and transcriptomic analyses on samples from 165 Chinese pediatric and adult T-ALL patients, of whom 85% have outcome information. The genomic mutation landscape of this Chinese cohort is very similar to the Western cohort published previously, except that the rate of NOTCH1 mutations is significant lower in the Chinese T-ALL patients. Among 47 recurrently mutated genes in 7 functional categories, we identify RAS pathway and PTEN mutations as poor survival factors for non-TAL and TAL subtypes, respectively. Mutations in the PI3K pathway are mutually exclusive with mutations in the RAS and NOTCH1 pathways as well as transcription factors. Further analysis demonstrates that approximately 43% of the high-risk patients harbor at least one potential actionable alteration identified in this study, and T-ALLs with RAS pathway mutations are hypersensitive to MEKi in vitro and in vivo. Thus, our integrated genomic analyses not only systematically identify high-risk factors but suggest that these high-risk factors are promising targets for T-ALL therapies.

What Is the Role of HSCT in Philadelphia-Chromosome-Positive and Philadelphia-Chromosome-Like ALL in the Tyrosine Kinase Inhibitor Era?

Previously, the outcome of paediatric Philadelphia-chromosome-positive (Ph+) ALL treated with conventional chemotherapy alone was poor, necessitating the use of haematopoietic stem cell transplantation (HSCT) for the best outcomes. The recent addition of tyrosine kinase inhibitors (TKIs) alongside the chemotherapy regimens for Ph+ ALL has markedly improved outcomes, replacing the need for HSCT for lower risk patients. An additional poor prognosis group of Philadelphia-chromosome-like (Ph-like) ALL has also been identified. This group also can be targeted by TKIs in combination with chemotherapy, but the role of HSCT in this population is not clear. The impact of novel targeted immunotherapies (chimeric antigen receptor T cells and bispecific or drug-conjugated antibodies) has improved the outcome of patients, in combination with chemotherapy, and made the role of HSCT as the optimal curative therapy for Ph+ ALL and Ph-like ALL less clear. The prognosis of patients with Ph+ ALL and persistent minimal residual disease (MRD) at the end of consolidation despite TKI therapy or with additional genetic risk factors remains inferior when HSCT is not used. For such high-risk patients, HSCT using total-body-irradiation-containing conditioning is currently recommended. This review aims to provide an update on the current and future role of HSCT for Ph+ ALL and addresses key questions related to the management of these patients, including the role of HSCT in first complete remission, MRD evaluation and related actions post HSCT, TKI usage post HSCT, and the putative role of HSCT in Ph-like ALL.

Therapeutic approach and outcome of children with Philadelphia chromosome-positive acute lymphoblastic leukemia at first relapse in the era of tyrosine kinase inhibitors: An SFCE retrospective study

BACKGROUND

Since the introduction of tyrosine kinase inhibitors (TKIs), the profile of pediatric relapse of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph⁺ ALL) has changed. However, the management of pediatric Ph⁺ ALL relapses is not currently standardized.

PROCEDURE

We retrospectively analyzed the therapeutic strategies and outcomes of pediatric Ph⁺ ALL patients in first relapse who were initially treated with a TKI-containing regimen in one of the French pediatric hematology centers from 2004 to 2019.

RESULTS

Twenty-seven children experienced a Ph⁺ ALL relapse: 24 (89%) had an overt relapse and three a molecular relapse. Eight involved the central nervous system. A second complete remission (CR2) was obtained for 26 patients (96%). Induction consisted of nonintensive chemotherapy for 13 patients (48%) and intensive chemotherapy for 14 (52%). Thirteen patients (48%) received consolidation. Allogenic hematopoietic stem cell transplantation (alloHSCT) was performed for 21 patients (78%). The TKI was changed for 23 patients (88%), mainly with dasatinib (n = 15). T315I was the most common mutation at relapse (4/7). The 4-year event-free survival and survival rates were 60.9% and 76.1%, respectively. Survival was positively associated with alloHSCT in CR2.

CONCLUSION

We show that pediatric first-relapse Ph⁺ ALL reinduces well with a second course of TKI exposure, despite the use of different therapeutic approaches. The main prognostic factor for survival was alloHSCT in CR2. Because of the small size of the cohort, we could not draw any conclusions about the respective impact of TKIs, but the predominance of the T315I mutation should encourage careful consideration of the TKI choice.

The functional role of inherited CDKN2A variants in childhood acute lymphoblastic leukemia

OBJECTIVE

Genetic alterations in CDKN2A tumor suppressor gene on chromosome 9p21 confer a predisposition to childhood acute lymphoblastic leukemia (ALL). Genome-wide association studies have identified missense variants in CDKN2A associated with the development of ALL. This study systematically evaluated the effects of CDKN2A coding variants on ALL risk.

METHODS

We genotyped the CDKN2A coding region in 308 childhood ALL cases enrolled in CCCG-ALL-2015 clinical trials by Sanger Sequencing. Cell growth assay, cell cycle assay, MTT-based cell toxicity assay, and western blot were performed to assess the CDKN2A coding variants on ALL predisposition.

RESULTS

We identified 10 novel exonic germline variants, including 6 missense mutations (p.A21V, p.G45A and p.V115L of p16INK4A; p.T31R, p.R90G, and p.R129L of p14ARF) and 1 nonsense mutation and 1 heterozygous termination codon mutation in exon 2 (p16INK4A p.S129X). Functional studies indicate that five novel variants resulted in reduced tumor suppressor activity of p16INK4A, and increased the susceptibility to the leukemic transformation of hematopoietic progenitor cells. Compared to other variants, p.H142R contributes higher sensitivity to CDK4/6 inhibitors.

CONCLUSION

These findings provide direct insight into the influence of inherited genetic variants at the CDKN2A coding region on the development of ALL and the precise clinical application of CDK4/6 inhibitors.

The cure of leukemia through the optimist's prism

Progress is occurring at a dizzying rate across all leukemias. Since the authors' review of the topic in Cancer in 2018, numerous discoveries have been made that have improved the therapy and outcomes of several leukemia subsets. Hairy cell leukemia is potentially curable with a single course of cladribine followed by rituximab (10-year survival, ≥90%). Acute promyelocytic leukemia is curable at a rate of 80% to 90% with a nonchemotherapy regimen of all-trans retinoic acid and arsenic trioxide. The cure rate for core-binding factor acute myeloid leukemia (AML) is ≥75% with fludarabine, high-dose cytarabine, and gemtuzumab ozogamicin. Survival for patients with chronic myeloid leukemia is close to that for an age-matched normal population with BCR-ABL1 tyrosine kinase inhibitors (TKIs). Chronic lymphocytic leukemia, a previously incurable disease, may now be potentially curable with a finite duration of therapy with Bruton tyrosine kinase inhibitors and venetoclax. The estimated 5-year survival rate for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) exceeds 70% with intensive chemotherapy and ponatinib, a third-generation BCR-ABL1 TKI, and more recent nonchemotherapy regimens using dasatinib or ponatinib with blinatumomab are producing outstanding results. Survival in both younger and older patients with ALL has improved with the addition of antibodies targeting CD20, CD19 (blinatumomab), and CD22 (inotuzumab) to chemotherapy. Several recent drug discoveries (venetoclax, FLT3 and IDH inhibitors, and oral hypomethylating agents) are also improving outcomes for younger and older patients with AML and for those with higher risk myelodysplastic syndrome.

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

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

Prognostic significance of CNSL at diagnosis of childhood B-cell acute lymphoblastic leukemia: A report from the South China Children's Leukemia Group

OBJECTIVES

The prognostic significance of acute lymphoblastic leukemia (ALL) patients with central nervous system leukemia (CNSL) at diagnosis is controversial. We aimed to determine the impact of CNSL at diagnosis on the clinical outcomes of childhood B-cell ALL in the South China Children's Leukemia Group (SCCLG).

METHODS

A total of 1,872 childhood patients were recruited for the study between October 2016 and July 2021. The diagnosis of CNSL depends on primary cytological examination of cerebrospinal fluid, clinical manifestations, and imaging manifestations. Patients with CNSL at diagnosis received two additional courses of intrathecal triple injections during induction.

RESULTS

The frequency of CNLS at the diagnosis of B-cell ALL was 3.6%. Patients with CNSL at diagnosis had a significantly higher mean presenting leukocyte count (P = 0.002) and poorer treatment response (P <0.05) compared with non-CNSL patients. Moreover, CNSL status was associated with worse 3-year event-free survival (P = 0.030) and a higher risk of 3-year cumulative incidence of relapse (P = 0.008), while no impact was observed on 3-year overall survival (P = 0.837). Multivariate analysis revealed that CNSL status at diagnosis was an independent predictor with a higher cumulative incidence of relapse (hazard ratio = 2.809, P = 0.016).

CONCLUSION

CNSL status remains an adverse prognostic factor in childhood B-cell ALL, indicating that additional augmentation of CNS-directed therapy is warranted for patients with CNSL at diagnosis.

Has Ph-like ALL Superseded Ph+ ALL as the Least Favorable Subtype?

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a subset of high-risk B-ALL associated with high relapse risk and inferior clinical outcomes across the pediatric-to-adult age spectrum. Ph-like ALL is characterized by frequent IKZF1 alterations and a kinase-activated gene expression profile similar to that of Philadelphia chromosome-positive (Ph+) ALL, yet lacks the canonical BCR-ABL1 rearrangement. Advances in high-throughput sequencing technologies during the past decade have unraveled the genomic landscape of Ph-like ALL, revealing a diverse array of kinase-activating translocations and mutations that may be amenable to targeted therapies that have set a remarkable precision medicine paradigm for patients with Ph + ALL. Collaborative scientific efforts to identify and characterise Ph-like ALL during the past decade has directly informed current precision medicine trials investigating the therapeutic potential of tyrosine kinase inhibitor-based therapies for children, adolescents, and adults with Ph-like ALL, although the most optimal treatment paradigm for this high-risk group of patients has yet to be established. Herein, we describe the epidemiology, clinical features, and biology of Ph-like ALL, highlight challenges in implementing pragmatic and cost-effective diagnostic algorithms in the clinic, and describe the milieu of treatment strategies under active investigation that strive to decrease relapse risk and improve long-term survival for patients with Ph-like ALL as has been successfully achieved for those with Ph + ALL.

Cytogenetic Characteristics of Childhood Acute Lymphoblastic Leukemia: A Study of 1541 Chinese Patients Newly Diagnosed between 2001 and 2014

OBJECTIVE

Cytogenetic abnormalities have been proven to be the most valuable parameter for risk stratification of childhood acute lymphoblastic leukemia (ALL). However, studies on the prevalence of cytogenetic abnormalities and their correlation to clinical features in Chinese pediatric patients are limited, especially large-scale studies.

METHODS

We collected the cytogenetics and clinical data of 1541 children newly diagnosed with ALL between 2001 and 2014 in four Chinese hospitals, and retrospectively analyzed their clinical features, prognosis and risk factors associated with pediatric ALL.

RESULTS

All of these patients had karyotyping results, and some of them were tested for fusion genes by fluorescence in situ hybridization or reverse-transcription polymerase chain reaction. Overall, 930 cases (60.4%) had abnormal cytogenetics in this study, mainly including high hyperdiploidy (HHD, n=276, 17.9%), hypodiploidy (n=74, 4.8%), t(12;21)/TEL-AML1 (n=260, 16.9%), t(1;19)/E2A-PBX1 (n=72, 4.7%), t(9;22)/BCR-ABL (n=64, 4.2%), and t(v;11q23)/MLL rearrangements (n=40, 2.6%). The distribution of each cytogenetic abnormality was correlated with gender, age, white blood cell count at diagnosis, and immunophenotype. In addition, multivariate analysis suggested that t(v;11q23)/MLL rearrangements (OR: 2.317, 95%CI: 1.219-3.748, P=0.008) and t(9;22)/BCR-ABL (OR: 2.519, 95%CI: 1.59-3.992, P<0.001) were independent risk factors for a lower event-free survival (EFS) rate in children with ALL, while HHD (OR: 0.638, 95%CI: 0.455-0.894, P=0.009) and t(12;21)/TEL-AML1 (OR: 0.486, 95%CI: 0.333-0.707, P<0.001) were independent factors of a favorable EFS.

CONCLUSION

The cytogenetic characteristics presented in our study resembled other research groups, emphasizing the important role of cytogenetic and molecular genetic classification in ALL, especially in B-ALL.

Genetic and Epigenetic Targeting Therapy for Pediatric Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia is the most common malignancy in children and is characterized by numerous genetic and epigenetic abnormalities. Epigenetic mechanisms, including DNA methylations and histone modifications, result in the heritable silencing of genes without a change in their coding sequence. Emerging studies are increasing our understanding of the epigenetic role of leukemogenesis and have demonstrated the potential of DNA methylations and histone modifications as a biomarker for lineage and subtypes classification, predicting relapse, and disease progression in acute lymphoblastic leukemia. Epigenetic abnormalities are relatively reversible when treated with some small molecule-based agents compared to genetic alterations. In this review, we conclude the genetic and epigenetic characteristics in ALL and discuss the future role of DNA methylation and histone modifications in predicting relapse, finally focus on the individual and precision therapy targeting epigenetic alterations.

Transcriptional and Mutational Profiling of B-Other Acute Lymphoblastic Leukemia for Improved Diagnostics

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common cancer in children, and significant progress has been made in diagnostics and the treatment of this disease based on the subtypes of BCP-ALL. However, in a large proportion of cases (B-other), recurrent BCP-ALL-associated genomic alterations remain unidentifiable by current diagnostic procedures. In this study, we performed RNA sequencing and analyzed gene fusions, expression profiles, and mutations in diagnostic samples of 185 children with BCP-ALL. Gene expression clustering showed that a subset of B-other samples partially clusters with some of the known subgroups, particularly DUX4-positive. Mutation analysis coupled with gene expression profiling revealed the presence of distinctive BCP-ALL subgroups, characterized by the presence of mutations in known ALL driver genes, e.g., PAX5 and IKZF1. Moreover, we identified novel fusion partners of lymphoid lineage transcriptional factors ETV6, IKZF1 and PAX5. In addition, we report on low blast count detection thresholds and show that the use of EDTA tubes for sample collection does not have adverse effects on sequencing and downstream analysis. Taken together, our findings demonstrate the applicability of whole-transcriptome sequencing for personalized diagnostics in pediatric ALL, including tentative classification of the B-other cases that are difficult to diagnose using conventional methods.

B-cell acute lymphoblastic leukaemia: recent discoveries in molecular pathology, their prognostic significance, and a review of the current classification

Acute lymphoblastic leukaemia (ALL) remains a leading cause of non-traumatic death in children, and the majority of adults diagnosed will succumb to the disease. Recent advances in molecular biology and bioinformatics have enabled more detailed genomic analysis and a better understanding of the molecular biology of ALL. A number of recurrent genomic drivers have recently been described, which not only aid in diagnosis and prognostication, but also may offer opportunities for specific therapeutic targeting. The present review summarises B-ALL genomic pathology at diagnosis, including lesions detectable using traditional cytogenetic methods as well as those detected only through advanced molecular techniques.

BCR/ABL1-positive B-lymphoblastic Lymphoma Successfully Treated with Dasatinib-combined Chemotherapy

We herein report a rare case of BCR-ABL1-positive B-lymphoblastic lymphoma (B-LBL). An 18-year-old woman had a history of persistent left-sided chest pain. Positron emission tomography showed increased metabolic activity in the fifth rib, duodenum, and pancreas. The pathological findings of the pancreas, duodenum, and bone marrow confirmed the diagnosis of B-LBL. Polymerase chain reaction of duodenum and bone marrow also revealed a minor BCR-ABL1 fusion gene. She was diagnosed with BCR-ABL1-positive B-LBL and administered dasatinib and prednisolone. She achieved complete remission two weeks after the initiation of the treatment. She received stem cell transplantation after consolidation chemotherapy and sustained complete remission.

Clinical Pharmacokinetics and Pharmacodynamics of Dasatinib

Dasatinib is an oral, once-daily tyrosine kinase inhibitor used in the treatment of chronic myeloid leukaemia and Philadelphia chromosome-positive acute lymphoblastic leukaemia. Dasatinib is rapidly absorbed, with the time for maximal serum concentration varying between 0.25 and 1.5 h. Oral absorption is not affected by food. The absolute bioavailability of dasatinib in humans is unknown due to the lack of an intravenous formulation preventing calculation of the reference exposure. Dasatinib is eliminated through cytochrome P450 (CYP) 3A4-mediated metabolism, with a terminal half-life of 3-4 h. Based on total radioactivity, only 20% of the oral dose (100 mg) is recovered unchanged in faeces (19%, including potential non-absorption) and urine (1%) after 168 h. Dasatinib pharmacokinetics are not influenced by age (children, and adults up to 86 years of age), race and renal insufficiency. Dasatinib absorption is decreased by pH-modifying agents (antacids, H₂-receptor blockers, proton pump inhibitors), and dasatinib is also subject to drug interactions with CYP3A4 inducers or inhibitors.

Targeted Therapy in the Treatment of Pediatric Acute Lymphoblastic Leukemia-Therapy and Toxicity Mechanisms

Targeted therapy has revolutionized the treatment of poor-prognosis pediatric acute lymphoblastic leukemia (ALL) with specific genetic abnormalities. It is still being described as a new landmark therapeutic approach. The main purpose of the use of molecularly targeted drugs and immunotherapy in the treatment of ALL is to improve the treatment outcomes and reduce the doses of conventional chemotherapy, while maintaining the effectiveness of the therapy. Despite promising treatment results, there is limited clinical research on the effect of target cell therapy on the potential toxic events in children and adolescents. The recent development of highly specific molecular methods has led to an improvement in the identification of numerous unique expression profiles of acute lymphoblastic leukemia. The detection of specific genetic mutations determines patients’ risk groups, which allows for patient stratification and for an adjustment of the directed and personalized target therapies that are focused on particular molecular alteration. This review summarizes the knowledge concerning the toxicity of molecular-targeted drugs and immunotherapies applied in childhood ALL.

Association of minimal residual disease with clinical outcomes in Philadelphia chromosome positive acute lymphoblastic leukemia in the tyrosine kinase inhibitor era: A systemic literature review and meta-analysis

Minimal residual disease (MRD) appeared to be a potent prognostic indicator in patients with Philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL), with potential value in informing individualized treatment decisions. Hence, we performed herein a systemic literature review and meta-analysis to comprehensively address the prognostic value of MRD in Ph+ ALL. Systematic literature review was conducted in PubMed, Embase, and Cochrane databases with the data access date up to September 23, 2020. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated with fixed-effects or random-effects models. Furthermore, subgroup analyses were performed to assess the robustness of the associations. 27 studies with a total number of 3289 patients were eligible for this meta-analysis. Combined HRs suggested that MRD positivity was associated with inferior event-free survival (EFS) (HR = 2.00, 95% CI 1.77–2.26) and overall survival (OS) (HR = 2.34, 95% CI 1.86–2.95). The associations remained statistically significant in subgroup analyses including age group, MRD timing, disease status at MRD, MRD cutoff level, et al. Our findings suggested MRD as a potent clinical tool for assessing the prognosis of Ph+ ALL. Further studies using MRD-based risk stratification might help optimize individualized treatment strategies for Ph+ ALL patients.

Acute Lymphoblastic Leukemia and Acute Lymphoblastic Lymphoma: Same Disease Spectrum but Two Distinct Diagnoses

PURPOSE OF REVIEW

Rare malignancies developing from lymphocyte precursor cells, lymphoblastic leukemia (LBL), and acute lymphoblastic lymphoma (ALL) have historically been viewed as different manifestations of the same disease process. This review examines data on their epidemiology, genetics, clinical presentation, and response to treatment while highlighting areas of similarity and divergence between these two clinical entities.

RECENT FINDINGS

Pediatric-type ALL chemotherapy regimens, compared to both lymphoma-type chemotherapy and adult-type ALL regimens, have led to improved outcomes for children, adolescents, and young adults with ALL. BCR-ABL-targeting tyrosine kinase inhibitors (TKIs) have improved outcomes in Philadelphia chromosome-positive (Ph +) ALL and in rare cases of Ph + LBL. Newer therapies including blinatumomab, inotuzumab, CAR-T therapy, and nelarabine have improved outcomes in selected cases of ALL and have an emerging role in the management of LBL. Better understanding of ALL and LBL biology allows for the development of therapies that target immunophenotypic or genetic features found in subsets of both diseases. Novel therapies are leading to improved outcomes in Ph + and relapsed and refractory disease.

SOHO State of the Art Updates & Next Questions: Intensive and Non-Intensive Approaches for Adults With Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) was historically considered to be a very poor-risk subtype of ALL. However, with the introduction of highly potent BCR-ABL tyrosine kinase inhibitors (TKIs), Ph+ ALL can now be considered relatively favorable-risk acute leukemia. Considering the high rates of measurable residual disease negativity and excellent long-term survival that has been achieved with regimens incorporating later-generation TKIs and particularly with ponatinib, lower-intensity and even chemotherapy-free regimens are now being evaluated for patients of all ages with Ph+ ALL. The very encouraging early results observed with blinatumomab-based, chemotherapy-free regimens challenge previous notions that all patients with Ph+ ALL should undergo allogeneic stem cell transplantation in first remission, as these regimens are capable of achieving deep and durable remissions without need for transplant in the vast majority of patients, particularly when combined with ponatinib. In this review, we discuss the evolving approach to the treatment of adults with newly diagnosed Ph+ ALL and the major principles that should guide therapy in this disease. We also review the rationale and data supporting the use of novel, chemotherapy-free regimens in Ph+ ALL, and how these approaches may soon become new standards of care.

Genetic Alterations in Childhood Acute Lymphoblastic Leukemia: Interactions with Clinical Features and Treatment Response

Acute lymphoblastic leukemia (ALL) is the most common cancer among children. This aggressive cancer comprises multiple molecular subtypes, each harboring a distinct constellation of somatic, and to a lesser extent, inherited genetic alterations. With recent advances in genomic analyses such as next-generation sequencing techniques, we can now clearly identify >20 different genetic subtypes in ALL. Clinically, identifying these genetic subtypes will better refine risk stratification and determine the optimal intensity of therapy for each patient. Underpinning each genetic subtype are unique clinical and therapeutic characteristics, such as age and presenting white blood cell (WBC) count. More importantly, within each genetic subtype, there is much less variability in treatment response and survival outcomes compared with current risk factors such as National Cancer Institute (NCI) criteria. We review how this new taxonomy of genetic subtypes in childhood ALL interacts with clinical risk factors used widely, i.e., age, presenting WBC, IKZF1del, treatment response, and outcomes.

Outcome of young adult patients with very-high-risk acute lymphoblastic leukemia treated with pediatric-type chemotherapy - a single institute experience

BACKGROUND/PURPOSE

Adult patients of acute lymphoblastic leukemia (ALL) with very high-risk (VHR) characteristics have an inferior outcome, and allogeneic hematopoietic stem cell transplantation (HSCT) is usually performed. In contrast, VHR pediatric patients can be treated effectively with minimal residual disease (MRD)-guided pediatric protocols and HSCT are not always needed.

METHODS

We retrospectively reviewed young adult ALL VHR patients treated with the pediatric-type (TPOG-ALL-2002 VHR) regimen in our institute from 2008 to 2019 and compared the event-free survival (EFS) with patients treated with an adult-type regimen (Hyper-CVAD alternating with high dose methotrexate and cytarabine).

RESULTS

We identified 16 patients treated with the TPOG and 11 treated with the Hyper-CVAD regimen. Philadelphia chromosome-positive (n = 10) and T-cell immunophenotype (n = 11) are the most common VHR features. Compared with the Hyper-CVAD group, patients treated with the TPOG regimen showed a trend toward better EFS with a hazard ratio (HR) of 0.42 (p = 0.16). Compared with untransplanted patients, HSCT showed a positive trend in the Hyper-CVAD (HR 0.22, p = 0.12) but not in the TPOG group (p = 0.37). Untransplanted patients treated initially with the hyper-CVAD regimen had a significantly worse outcome than the TPOG regimen (HR 4.19, p < 0.05). In the TPOG group, patients with negative MRD at the end of consolidation had a significantly better outcome (HR 0.12, p = 0.03).

CONCLUSION

Young adult VHR patients can be effectively treated with the TPOG-ALL-2002 protocol, and those who achieved MRD negativity before the end of consolidation have a good outcome without allogeneic HSCT.

Prognostic factors for CNS control in children with acute lymphoblastic leukemia treated without cranial irradiation

To identify the prognostic factors that are useful to improve central nervous system (CNS) control in children with acute lymphoblastic leukemia (ALL), we analyzed the outcome of 7640 consecutive patients treated on Chinese Children's Cancer Group ALL-2015 protocol between 2015 and 2019. This protocol featured prephase dexamethasone treatment before conventional remission induction and subsequent risk-directed therapy, including 16 to 22 triple intrathecal treatments, without prophylactic cranial irradiation. The 5-year event-free survival was 80.3% (95% confidence interval [CI], 78.9-81.7), and overall survival 91.1% (95% CI, 90.1-92.1). The cumulative risk of isolated CNS relapse was 1.9% (95% CI, 1.5-2.3), and any CNS relapse 2.7% (95% CI, 2.2-3.2). The isolated CNS relapse rate was significantly lower in patients with B-cell ALL (B-ALL) than in those with T-cell ALL (T-ALL) (1.6%; 95% CI, 1.2-2.0 vs 4.6%; 95% CI, 2.9-6.3; P < .001). Independent risk factors for isolated CNS relapse included male sex (hazard ratio [HR], 1.8; 95% CI, 1.1-3.0; P = .03), the presence of BCR-ABL1 fusion (HR, 3.8; 95% CI, 2.0-7.3; P < .001) in B-ALL, and presenting leukocyte count ≥50×109/L (HR, 4.3; 95% CI, 1.5-12.2; P = .007) in T-ALL. Significantly lower isolated CNS relapse was associated with the use of total intravenous anesthesia during intrathecal therapy (HR, 0.2; 95% CI, 0.04-0.7; P = .02) and flow cytometry examination of diagnostic cerebrospinal fluid (CSF) (HR, 0.2; 95% CI, 0.06-0.6; P = .006) among patients with B-ALL. Prephase dexamethasone treatment, delayed intrathecal therapy, use of total intravenous anesthesia during intrathecal therapy, and flow cytometry examination of diagnostic CSF may improve CNS control in childhood ALL. This trial was registered with the Chinese Clinical Trial Registry (ChiCTR-IPR-14005706).

Pulse therapy with vincristine and dexamethasone for childhood acute lymphoblastic leukaemia (CCCG-ALL-2015): an open-label, multicentre, randomised, phase 3, non-inferiority trial

BACKGROUND

Vincristine plus dexamethasone pulses are generally used throughout maintenance treatment for childhood acute lymphoblastic leukaemia. However, previous studies remain inconclusive about the benefit of this maintenance therapy and the absence of randomised, controlled trials in patients with low-risk or high-risk acute lymphoblastic leukaemia provides uncertainty. We therefore aimed to determine if this therapy could be safely omitted beyond 1 year of treatment without leading to an inferior outcome in any risk subgroup of childhood acute lymphoblastic leukaemia.

METHODS

This open-label, multicentre, randomised, phase 3, non-inferiority trial involved 20 major medical centres across China. We enrolled patients who were aged 0-18 years with newly diagnosed acute lymphoblastic leukaemia that was subsequently in continuous remission for 1 year after initial treatment. Patients with secondary malignancy or primary immunodeficiency were excluded. Eligible patients were classified as having low-risk, intermediate-risk, or high-risk acute lymphoblastic leukaemia based on minimal residual disease and immunophenotypic and genetic features of leukaemic cells. Randomisation and analyses were done separately for the low-risk and intermediate-to-high-risk cohorts. Randomisation was generated by the study biostatistician with a block size of six. Stratification factors included participating centre, sex, and age at diagnosis; the low-risk cohort was additionally stratified for ETV6-RUNX1 status, and the intermediate-to-high-risk cohort for cell lineage. Patients in each risk cohort were randomly assigned (1:1) to either receive (ie, the control group) or not receive (ie, the experimental group) seven pulses of intravenous vincristine (1·5 mg/m²) plus oral dexamethasone (6 mg/m² per day for 7 days) during the second year of treatment. The primary endpoint was difference in 5-year event-free survival between the experimental group and the control group for both the low-risk and intermediate-to-high-risk cohorts, with a non-inferiority margin of 0·05 (5%). The analysis was by intention to treat. This trial is registered with the Chinese Clinical Trial Registry, ChiCTR-IPR-14005706.

FINDINGS

Between Jan 1, 2015, and Feb 20, 2020, 6141 paediatric patients with newly diagnosed acute lymphoblastic leukaemia were registered to this study. Approximately 1 year after diagnosis and treatment, 5054 patients in continuous remission were randomly assigned, including 2923 (1442 in the control group and 1481 in the experimental group) with low-risk acute lymphoblastic leukaemia and 2131 (1071 control, 1060 experimental) with intermediate-to-high risk acute lymphoblastic leukaemia. Median follow-up for patients who were alive at the time of analysis was 3·7 years (IQR 2·8-4·7). Among patients with low-risk acute lymphoblastic leukaemia, no difference was observed in 5-year event-free survival between the control group and the experimental group (90·3% [95% CI 88·4-92·2] vs 90·2% [88·2-92·2]; p=0·90). The one-sided 95% upper confidence bound for the difference in 5-year event-free survival probability was 0·024, establishing non-inferiority. Among patients with intermediate-to-high-risk acute lymphoblastic leukaemia, no difference was observed in 5-year event-free survival between the control group and the experimental group (82·8% [95% CI 80·0-85·7] vs 80·8% [77·7-84·0]; p=0·90), but the one-sided 95% upper confidence bound for the difference in 5-year event-free survival probability was 0·055, giving a borderline inferior result for those in the experimental group. In the low-risk cohort, we found no differences in the rates of infections, symptomatic osteonecrosis, or other complications during the second year of maintenance treatment between patients in the control and experimental groups. Patients with intermediate-to-high-risk acute lymphoblastic leukaemia in the control group were more likely to develop grade 3-4 pneumonia (26 [2·4%] of 1071 vs ten [0·9%] of 1060) and vincristine-related peripheral neuropathy (17 [1·6%] vs six [0·6%]) compared with the experimental group. Incidence of grade 5 fatal infection was similar between the control group and the experimental group in both the low-risk cohort (two [0·1%] of 1442 vs five [0·3%] of 1481) and intermediate-to-high risk cohort (six [0·6%] of 1071 vs five [0·5%] of 1060).

INTERPRETATION

Vincristine plus dexamethasone pulses might be omitted beyond 1 year of treatment for children with low-risk acute lymphoblastic leukaemia. Additional studies are needed for intermediate-to-high-risk acute lymphoblastic leukaemia.

FUNDING

VIVA China Children's Cancer Foundation, the National Natural Science Foundation of China, the China fourth round of Three-Year Public Health Action Plan (2015-2017), Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences, US National Cancer Institute, St Baldrick's Foundation, and the American Lebanese Syrian Associated Charities.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Emerging tyrosine kinase inhibitors for the treatment of adult acute lymphoblastic leukemia

Introduction: The broadening of targeted and immunotherapeutic strategies markedly impacted on the management of acute lymphoblastic leukemia (ALL). The advent of tyrosine kinase inhibitors (TKIs) changed the history of Philadelphia-chromosome positive (Ph+) ALL. Nowadays, almost all Ph+ ALL patients treated with TKIs achieve a complete hematologic response, and most become minimal residual disease negative. In Ph- ALL, genomic profiling studies have identified a subtype associated with a high relapse risk and a transcriptional profile similar to that of Ph+ ALL, the so-called Ph-like ALL. Given the high prevalence of kinase-activating lesions in this subset, there is compelling evidence from experimental models and clinical observations favoring TKI administration.Areas covered: We discuss the main findings exploring the efficacy of TKIs in ALL.Expert opinion: The use of more potent TKIs will further enhance the inhibitory activity on leukemia cells and increase the possibility of eradicating the disease at a molecular level. In the future, 'combined' approaches of different inhibitors may be considered to prevent/avoid resistance and/or mutations. A rapid identification of Ph-like ALL patients is needed to propose early TKI-based intervention. Several questions remain open, including the initial TKI choice in Ph+ ALL and whether Ph-like ALL patients might benefit from immunotherapy.

Targeted Therapy in Acute Lymphoblastic Leukaemia

The last decade has seen a significant leap in our understanding of the wide range of genetic lesions underpinning acute lymphoblastic leukaemia (ALL). Next generation sequencing has led to the identification of driver mutations with significant implications on prognosis and has defined entities such as BCR-ABL-like ALL, where targeted therapies such as tyrosine kinase inhibitors (TKIs) and JAK inhibitors may play a role in its treatment. In Philadelphia positive ALL, the introduction of TKIs into frontline treatment regimens has already transformed patient outcomes. In B-ALL, agents targeting surface receptors CD19, CD20 and CD22, including monoclonal antibodies, bispecific T cell engagers, antibody drug conjugates and chimeric antigen receptor (CAR) T cells, have shown significant activity but come with unique toxicities and have implications for how treatment is sequenced. Advances in T-ALL have lagged behind those seen in B-ALL. However, agents such as nelarabine, bortezomib and CAR T cell therapy targeting T cell antigens have been examined with promising results seen. As our understanding of disease biology in ALL grows, as does our ability to target pathways such as apoptosis, through BH3 mimetics, chemokines and epigenetic regulators. This review aims to highlight a range of available and emerging targeted therapeutics in ALL, to explore their mechanisms of action and to discuss the current evidence for their use.