Current and future management of Ph/BCR-ABL positive ALL

Detection of kinase domain mutations in BCR::ABL1 leukemia by ultra-deep sequencing of genomic DNA

The screening of the BCR::ABL1 kinase domain (KD) mutation has become a routine analysis in case of warning/failure for chronic myeloid leukemia (CML) and B-cell precursor acute lymphoblastic leukemia (ALL) Philadelphia (Ph)-positive patients. In this study, we present a novel DNA-based next-generation sequencing (NGS) methodology for KD ABL1 mutation detection and monitoring with a 1.0E-4 sensitivity. This approach was validated with a well-stablished RNA-based nested NGS method. The correlation of both techniques for the quantification of ABL1 mutations was high (Pearson r = 0.858, p < 0.001), offering DNA-DeepNGS a sensitivity of 92% and specificity of 82%. The clinical impact was studied in a cohort of 129 patients (n = 67 for CML and n = 62 for B-ALL patients). A total of 162 samples (n = 86 CML and n = 76 B-ALL) were studied. Of them, 27 out of 86 harbored mutations (6 in warning and 21 in failure) for CML, and 13 out of 76 (2 diagnostic and 11 relapse samples) did in B-ALL patients. In addition, in four cases were detected mutation despite BCR::ABL1 < 1%. In conclusion, we were able to detect KD ABL1 mutations with a 1.0E-4 sensitivity by NGS using DNA as starting material even in patients with low levels of disease.

Mapping incidence and mortality of leukemia and its subtypes in 21 world regions in last three decades and projections to 2030

This study examines the burden of leukemia and its subtypes at the global, regional, and national levels in 21 world regions and 204 countries in the last three decades. The estimates of incidence, deaths, and age-standardized rates of leukemia for 21 regions and 204 countries for 1990-2019 were extracted from the Global Burden of Disease 2019 study. Average annual percentage change in 1990-2019 for 21 regions was utilized for projecting leukemia burden in 2030. Globally, there were 643,579 [586,980-699,729] incident cases and 334,592 [306,818-360,214] deaths in 2019 due to leukemia, up from 474,924 [388,559-560,550] cases and 263,263 [233,664-298,696] deaths in 1990. Between 1990 and 2019, the age-standardized incidence rate (ASIR) decreased from 9.6 [8.1-11.0] in 1990 to 8.2 [7.5-8.9] per 100,000 person-years in 2019, and the age-standardized mortality rate (ASMR) decreased from 5.8/100,000 [5.2-6.4] in 1990 to 4.3/100,000 [3.9-4.6] in 2019. Between 1990 and 2019, the ASIR decreased in majority of regions except Western Europe and high-income Asia Pacific, whereas the ASMR decreased in all 21 regions. In 2019, country-wise, the ASIR varied from 3.0/100,000 [2.3-3.7] in Palau to 35.1/100,000 [26.4-47.2] in San Marino and the ASMR spanned from 2.3/100,000 [1.7-2.8] in San Marino to 15.8/100,000 [12.0-20.4] in Syria. As per our projections, globally, there will be 720,168 incident cases and 367,804 deaths due to leukemia in 2030. Substantial improvements have been witnessed in leukemia mortality rates in all regions, especially high-income regions and countries. Health care policies focusing on diagnostic improvements, cancer registration, and newer therapeutics at reduced cost or with insurance coverage are needed in low and middle-income countries.

A novel imatinib-upregulated long noncoding RNA plays a critical role in inhibition of tumor growth induced by Abl oncogenes

BACKGROUND

Dysregulation of long noncoding RNAs (lncRNAs) has been linked to various human cancers. Bcr-Abl oncogene that results from a reciprocal translocation between human chromosome 9 and 22, is associated with several hematological malignancies. However, the role of lncRNAs in Bcr-Abl-induced leukemia remains largely unexplored.

METHODS

LncRNA cDNA microarray was employed to identify key lncRNAs involved in Bcr-Abl-mediated cellular transformation. Abl-transformed cell survival and xenografted tumor growth in mice were evaluated to dissect the role of imatinib-upregulated lncRNA 1 (IUR1) in Abl-induced tumorigenesis. Primary bone marrow transformation and in vivo leukemia transplant using lncRNA-IUR1 knockout (KO) mice were further conducted to address the functional relevance of lncRNA-IUR1 in Abl-mediated leukemia. Transcriptome RNA-seq and Western blotting were performed to determine the mechanisms by which lncRNA-IUR1 regulates Bcr-Abl-induced tumorigenesis.

RESULTS

We identified lncRNA-IUR1 as a critical negative regulator of Bcr-Abl-induced tumorigenesis. LncRNA-IUR1 expressed in a very low level in Bcr-Abl-positive cells from chronic myeloid leukemia patients. Interestingly, it was significantly induced in Abl-positive leukemic cells treated by imatinib. Depletion of lncRNA-IUR1 promoted survival of Abl-transformed human leukemic cells in experiments in vitro and xenografted tumor growth in mice, whereas ectopic expression of lncRNA-IUR1 sensitized the cells to apoptosis and suppressed tumor growth. In concert, silencing murine lncRNA-IUR1 in Abl-transformed cells accelerated cell survival and the development of leukemia in mice. Furthermore, lncRNA-IUR1 deficient mice were generated, and we observed that knockout of murine lncRNA-IUR1 facilitated Bcr-Abl-mediated primary bone marrow transformation. Moreover, animal leukemia model revealed that lncRNA-IUR1 deficiency promoted Abl-transformed cell survival and development of leukemia in mice. Mechanistically, we demonstrated that lncRNA-IUR1 suppressed Bcr-Abl-induced tumorigenesis through negatively regulating STAT5-mediated GATA3 expression.

CONCLUSIONS

These findings unveil an inhibitory role of lncRNA-IUR1 in Abl-mediated cellular transformation, and provide new insights into molecular mechanisms underlying Abl-induced leukemogenesis.

Dasatinib-based Two-step Induction for Adults with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Dasatinib-based 2-step induction resulted in a 100% CR rate with minimal toxicities and 53% MRD negativity.

This protocol treatment increased the number of HSCTs in CR1, thereby improving 3-year EFS.

The standard treatment for adults with Philadelphia chromosome–positive (Ph⁺) acute lymphoblastic leukemia (ALL) in Japan is imatinib-based chemotherapy followed by allogeneic hematopoietic stem cell transplantation (HSCT). However, ∼40% of patients cannot undergo HSCT in their first complete remission (CR1) because of chemotherapy-related toxicities or relapse before HSCT or older age. In this study, we evaluated dasatinib-based 2-step induction with the primary end point of 3-year event-free survival (EFS). The first induction (IND1) was dasatinib plus prednisolone to achieve CR, and IND2 was dasatinib plus intensive chemotherapy to achieve minimal residual disease (MRD) negativity. For patients who achieved CR and had an appropriate donor, HSCT during a consolidation phase later than the first consolidation, which included high-dose methotrexate, was recommended. Patients with pretransplantation MRD positivity were assigned to receive prophylactic dasatinib after HSCT. All 78 eligible patients achieved CR or incomplete CR after IND1, and 52.6% achieved MRD negativity after IND2. Nonrelapse mortality (NRM) was not reported. T315I mutation was detected in all 4 hematological relapses before HSCT. Fifty-eight patients (74.4%) underwent HSCT in CR1, and 44 (75.9%) had negative pretransplantation MRD. At a median follow-up of 4.0 years, 3-year EFS and overall survival were 66.2% (95% confidence interval [CI], 54.4-75.5) and 80.5% (95% CI, 69.7-87.7), respectively. The cumulative incidence of relapse and NRM at 3 years from enrollment were 26.1% and 7.8%, respectively. Dasatinib-based 2-step induction was demonstrated to improve 3-year EFS in Ph⁺ ALL. This study was registered in the UMIN Clinical Trial Registry as #UMIN000012173.

Consensus Recommendations for MRD Testing in Adult B-Cell Acute Lymphoblastic Leukemia in Ontario

Measurable (minimal) residual disease (MRD) is an established, key prognostic factor in adult B-cell acute lymphoblastic leukemia (B-ALL), and testing for MRD is known to be an important tool to help guide treatment decisions. The clinical value of MRD testing depends on the accuracy and reliability of results. Currently, there are no Canadian provincial or national guidelines for MRD testing in adult B-ALL, and consistent with the absence of such guidelines, there is no uniform Ontario MRD testing consensus. Moreover, there is great variability in Ontario in MRD testing with respect to where, when, and by which technique, MRD testing is performed, as well as in how the results are interpreted. To address these deficiencies, an expert multidisciplinary working group was convened to define consensus recommendations for improving the provision of such testing. The expert panel recommends that MRD testing should be implemented in a centralized manner to ensure expertise and accuracy in testing for this low volume indication, thereby to provide accurate, reliable results to clinicians and patients. All adult patients with B-ALL should receive MRD testing after induction chemotherapy. Philadelphia chromosome (Ph)-positive patients should have ongoing monitoring of MRD during treatment and thereafter, while samples from Ph-negative B-ALL patients should be tested at least once later during treatment, ideally at 12 to 16 weeks after treatment initiation. In Ph-negative adult B-ALL patients, standardized, ideally centralized, protocols must be used for MRD testing, including both flow cytometry and immunoglobulin (Ig) heavy chain and T-cell receptor (TCR) gene rearrangement analysis. For Ph-positive B-ALL patients, MRD testing using a standardized protocol for reverse transcription real-time quantitative PCR (RT-qPCR) for the BCR-ABL1 gene fusion transcript is recommended, with Ig/TCR gene rearrangement analysis done in parallel likely providing additional clinical information.

Long-term follow-up of blinatumomab in patients with relapsed/refractory Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukaemia: Final analysis of ALCANTARA study

AIM

To evaluate long-term durability of blinatumomab, a BiTE® (bispecific T-cell engager) molecule, in adults with relapsed/refractory (R/R) Philadelphia chromosome-positive (Ph+) B-cell precursor acute lymphoblastic leukaemia (ALL).

METHODS

In this final analysis of an open-label, single-arm, phase 2, multicentre ALCANTARA study (NCT02000427), adults (age ≥18 years) with Ph+ ALL who had relapsed or were refractory to at least one TKI were included. The primary endpoint was the proportion of patients who achieved complete remission (CR)/CR with partial haematologic recovery (CRh) during the first two cycles of blinatumomab treatment.

RESULTS

The final analysis included 45 patients who completed the study between 3rd January 2014 and 6th January 2017, of which 16 (35.6%; 95% CI, 21.9%-51.2%) achieved CR/CRh within the first two blinatumomab cycles. After a median follow-up of 16.1 months, median relapse-free survival (RFS) was 6.8 (95% CI, 4.4-not estimable [NE]) months. Median overall survival (OS) was 9.0 (95% CI, 5.7-13.5) months with a median follow-up of 25.1 months. Median OS in patients with CR (19.8 [95% CI, 12.1-NE] months) was greater than in those without CR (6.0 [95% CI, 2.9-7.1] months). Of 16 patients with CR/CRh, 14 achieved complete minimal residual disease (MRD) response; the median duration of complete MRD response was 9.7 (95% CI, 5.2-NE) months. Treatment-related adverse events were consistent with those previously reported.

CONCLUSION

Long-term durability of responses to blinatumomab was demonstrated in patients with R/R Ph+ ALL.

Treatment and outcome of Philadelphia chromosome-positive acute lymphoblastic leukemia in adults after relapse

INTRODUCTION

Despite the significant progress that has been made over the last years in the front-line treatment of Philadelphia (Ph) chromosome-positive acute lymphoblastic leukemia (ALL), relapses are frequent and their treatment remains a challenge, especially among patients with resistant BCR-ABL1 mutations.

AREAS COVERED

This manuscript reviews available data for the treatment of adult patients with relapsed/refractory Ph-positive ALL, with a focus on the role of tyrosine kinase inhibitors (TKIs), monoclonal antibodies, and immunotherapy.

EXPERT OPINION

Although a majority of patients with first relapsed Ph-positive ALL respond to subsequent salvage chemotherapy plus TKI combination, their outcomes remain poor. The main predictor of survival is the achievement of major molecular response anytime during the morphological response. More treatment strategies to improve survival are under investigation. Monoclonal antibodies and bispecific antibody constructs hold considerable promise in improving the outcomes of patients with relapsed ALL including Ph-positive ALL.

The Q-LAMP Method Represents a Valid and Rapid Alternative for the Detection of the BCR-ABL1 Rearrangement in Philadelphia-Positive Leukemias

Molecular detection of the BCR-ABL1 fusion transcripts is necessary for the genetic confirmation of a chronic myeloid leukemia diagnosis and for the risk classification of acute lymphoblastic leukemia. BCR-ABL1 mRNAs are usually identified using a conventional RT-PCR technique according to the BIOMED-1 method. In this study, we evaluated 122 BCR-ABL1-positive samples with the Q-LAMP assay to establish if this technology may represent a valid alternative to the qualitative BIOMED-1 PCR technique usually employed for the detection and the discrimination of the common BCR-ABL1 transcripts (p190 and p210 isoforms). We found a 100% concordance rate between the two methods. Specifically, the p190- and p210-positive samples were amplified by Q-LAMP with a median threshold time (Tt) of 26.70 min (range: 24.45-31.80 min) and 20.26 min (range: 15.25-34.57 min), respectively. A median time of 19.63 was observed in samples displaying both (e13a2/e14a2) p210 isoforms. Moreover, the Q-LAMP assay allowed recognition of the BCR-ABL1 e13a2 and e14a2 isoforms (median Tts 18.48 for e13a2 vs. 26.08 min for e14a2; p < 0.001). Finally, 20 samples harboring rare BCR-ABL1 isoforms (e1a3, e13a3, e14a3, and e19a2) were correctly identified by the Q-LAMP assay. We conclude that the Q-LAMP assay may represent a faster and valid alternative to the qualitative BIOMED-1 RT-PCR for the diagnosis at BCR-ABL1-positive leukemias, especially when samples are analyzed in centers with restricted resources and/or limited technical expertise.

Minimal Residual Disease in Acute Lymphoblastic Leukemia: Technical and Clinical Advances

Introduction: Acute lymphoblastic leukemia (ALL) is the first neoplasm where the assessment of early response to therapy by minimal residual disease (MRD) monitoring has proven to be a fundamental tool to guide therapeutic choices. The most standardized methods to study MRD in ALL are multi-parametric flow cytometry (MFC) and polymerase chain reaction (PCR) amplification-based methods. Emerging technologies hold the promise to improve MRD detection in ALL patients. Moreover, novel therapies, such as monoclonal antibodies, bispecific T-cell engagers, and chimeric antigen receptor T cells (CART) represent exciting advancements in the management of B-cell precursor (BCP)-ALL.

Aims: Through a review of the literature and in house data, we analyze the current status of MRD assessment in ALL to better understand how some of its limitations could be overcome by emerging molecular technologies. Furthermore, we highlight the future role of MRD monitoring in the context of personalized protocols, taking into account the genetic complexity in ALL.

Results and Conclusions: Molecular rearrangements (gene fusions and immunoglobulin and T-cell receptor-IG/TR gene rearrangements) are widely used as targets to detect residual leukemic cells in ALL patients. The advent of novel techniques, namely next generation flow cytometry (NGF), digital-droplet-PCR (ddPCR), and next generation sequencing (NGS) appear important tools to evaluate MRD in ALL, since they have the potential to overcome the limitations of standard approaches. It is likely that in the forthcoming future these techniques will be incorporated in clinical trials, at least at decisional time points. Finally, the advent of new powerful compounds is further increasing MRD negativity rates, with benefits in long-term survival and a potential reduction of therapy-related toxicities. However, the prognostic relevance in the setting of novel immunotherapies still needs to be evaluated.

Treatment and monitoring of Philadelphia chromosome-positive leukemia patients: recent advances and remaining challenges

The Philadelphia (Ph) chromosome, resulting from the t(9;22)(q34;q11) translocation, can be found in chronic myeloid leukemia (CML) as well as in a subset of acute lymphoblastic leukemias (ALL). The deregulated BCR-ABL1 tyrosine kinase encoded by the fusion gene resulting from the translocation is considered the pathogenetic driver and can be therapeutically targeted. In both CML and Ph-positive (Ph+) ALL, tyrosine kinase inhibitors (TKIs) have significantly improved outcomes. In the TKI era, testing for BCR-ABL1 transcript levels by real-time quantitative polymerase chain reaction (RQ-PCR) has become the gold standard to monitor patient response, anticipate relapse, and guide therapeutic decisions. In CML, key molecular response milestones have been defined that draw the ideal trajectory towards optimal long-term outcomes. Treatment discontinuation (treatment-free remission, TFR) has proven feasible in a proportion of patients, and clinical efforts are now focused on how to increase this proportion and how to best select TFR candidates. In Ph+ ALL, results of trials with second- and third-generation TKIs are challenging the role of intensive chemotherapy and even that of allogeneic stem cell transplantation. Additional weapons are offered by the recently introduced monoclonal antibodies. In patients harboring mutations in the BCR-ABL1 kinase domain, prompt therapeutic reassessment and individualization based on mutation status are important to regain response and prevent disease progression. Next-generation sequencing is likely to become a precious tool for mutation testing because of the greater sensitivity and the possibility to discriminate between compound and polyclonal mutations. In this review, we discuss the latest advances in treatment and monitoring of CML and Ph+ ALL and the issues that still need to be addressed to make the best use of the therapeutic armamentarium and molecular testing technologies currently at our disposal.

New Approaches to the Management of Adult Acute Lymphoblastic Leukemia

Traditional treatment regimens for adult acute lymphoblastic leukemia, including allogeneic hematopoietic cell transplantation, result in an overall survival of approximately 40%, a figure hardly comparable with the extraordinary 80% to 90% cure rate currently reported in children. When translated to the adult setting, modern pediatric-type regimens improve the survival to approximately 60% in young adults. The addition of tyrosine kinase inhibitors for patients with Philadelphia chromosome-positive disease and the measurement of minimal residual disease to guide risk stratification and postremission approaches has led to additional improvements in outcomes. Relapsed disease and treatment toxicity-sparing no patient but representing a major concern especially in the elderly-are the most critical current issues awaiting further therapeutic advancement. Recently, there has been considerable progress in understanding the disease biology, specifically the Philadelphia-like signature, as well as other high-risk subgroups. In addition, there are several new agents that will undoubtedly contribute to additional improvement in the current outcomes. The most promising agents are monoclonal antibodies, immunomodulators, and chimeric antigen receptor T cells, and, to a lesser extent, several new drugs targeting key molecular pathways involved in leukemic cell growth and proliferation. This review examines the evidence supporting the increasing role of the new therapeutic tools and treatment options in different disease subgroups, including frontline and relapsed or refractory disease. It is now possible to define the best individual approach on the basis of the emerging concepts of precision medicine.

Minimal Residual Disease Assessment and Risk-based Therapy in Acute Lymphoblastic Leukemia

The study of minimal residual disease (MRD) in adult patients with acute lymphoblastic leukemia (ALL) allows a greater refinement of the individual risk classification and is the best support for risk-specific therapy with or without allogeneic hematopoietic cell transplantation (HCT). Using case-specific sensitive molecular probes or multiparametric flow cytometry on marrow samples obtained from the end of induction until midconsolidation, MRD assays can detect up to 1 leukemic cell of 10,000 total mononuclear cells (sensitivity, 0.01%; ie, ≥10⁴). This cutoff, presently bound to technical limitations and subject to improvement, reflects the individual chemosensitivity and is strongly correlated with treatment outcome. The chance for cure is approximately 70% in the MRD-negative subset but only 20% to 30% in MRD-positive patients, in any diagnostic and risk subset. As shown by prospective trials from Germany, Italy, Spain, and France-Switzerland-Belgium, approximately 50% to 70% of unselected adult patients with Philadelphia-negative ALL achieve and maintain an early MRD response, whereas the remainder do not, including a substantial proportion of clinically standard-risk patients, and require an HCT to avert at least partially the risk of relapse. Along with the diffusion of more effective "pediatric-inspired" chemotherapy programs, the MRD analysis is an integral part of a modern management strategy, guiding the decision process to transplant or not, in which case nonrelapse mortality using HCT in first remission-still 10% to 20%-is totally abolished. The use of new agents such as monoclonal antibodies, small inhibitors, and chimeric antigen receptor T cells is opening a new era of MRD-directed therapies, that will further increase survival rates.

Novel multiple tyrosine kinase inhibitor ponatinib inhibits bFGF-activated signaling in neuroblastoma cells and suppresses neuroblastoma growth in vivo

Neuroblastoma (NB) is one of the most common pediatric malignancies in children. Abnormal activation of receptor tyrosine kinases contributes to the pathological development of NB. Therefore, targeting tyrosine kinase receptors to cure NB is a promising strategy. Here, we report that a multi-targeted tyrosine kinase inhibitor ponatinib inhibited NB cell proliferation and induced NB cell apoptosis in a dose-dependent manner. In addition, ponatinib suppressed the colony formation ability of NB cells. Mechanistically, ponatinib effectively inhibited the FGFR1-activated signaling pathway. Ponatinib also enhanced the cytotoxic effects of doxorubicin on NB cells. Furthermore, ponatinib demonstrated anti-tumor efficacy in vivo by inhibiting tumor growth in an orthotopic xenograft NB mouse model. In summary, our results showed that ponatinib inhibited NB growth both in vitro and in vivo.

Ponatinib-Induced Graft-versus-Host Disease/Graft-versus-Leukemia Effect in a Patient with Philadelphia-Positive Acute Lymphoblastic Leukemia without the T315I Mutation Relapsing after Allogeneic Transplant

We describe the case of a patient with Philadelphia-positive acute lymphoblastic leukemia treated with dasatinib plus steroids as first-line therapy, who achieved a major molecular response (MMR) before undergoing matched, unrelated donor allogeneic stem cell transplant. Eleven months after the transplant, she experienced molecular relapse. Mutational screening showed negativity for the T315I mutation, The patient underwent a salvage chemotherapy regimen with clofarabine + cyclophosphamide + steroids and ponatinib (clofarabine 70 mg i.v., days 1-5, cyclophosphamide 700 mg i.v., days 1-5, and ponatinib 45 mg p.o., daily starting at day 15). We observed a rapid decrease in minimal residual disease on molecular assessment with an MMR of P190-BCR-ABL/ABL = 0.01% confirmed by bone marrow revaluations at days +23, +59, +108, and +191 after the first day of salvage chemotherapy. After starting ponatinib, the patient experienced skin graft-versus-host disease, suggesting that the efficacy of ponatinib could be related not only to the direct antileukemic effect but also to its ability to promote an indirect graft-versus-leukemia effect. Ponatinib treatment was well tolerated and considered safe with easily manageable side effects.

Complete Hematologic and Molecular Response in Adult Patients With Relapsed/Refractory Philadelphia Chromosome-Positive B-Precursor Acute Lymphoblastic Leukemia Following Treatment With Blinatumomab: Results From a Phase II, Single-Arm, Multicenter Study

Purpose Few therapeutic options are available for patients with Philadelphia chromosome-positive (Ph⁺) B-precursor acute lymphoblastic leukemia (ALL) who progress after failure of tyrosine kinase inhibitor (TKI) -based therapy. Here, we evaluated the efficacy and tolerability of blinatumomab in patients with relapsed or refractory Ph⁺ ALL. Patients and Methods This open-label phase II study enrolled adults with Ph⁺ ALL who had relapsed after or were refractory to at least one second-generation or later TKI or were intolerant to second-generation or later TKIs and intolerant or refractory to imatinib. Blinatumomab was administered in 28-day cycles by continuous intravenous infusion. The primary end point was complete remission (CR) or CR with partial hematologic recovery (CRh) during the first two cycles. Major secondary end points included minimal residual disease response, rate of allogeneic hematopoietic stem-cell transplantation, relapse-free survival, overall survival, and adverse events (AEs). Results Of 45 patients, 16 (36%; 95% CI, 22% to 51%) achieved CR/CRh during the first two cycles, including four of 10 patients with the T315I mutation; 88% of CR/CRh responders achieved a complete minimal residual disease response. Seven responders (44%) proceeded to allogeneic hematopoietic stem-cell transplantation, including 55% (six of 11) of transplantation-naïve responders. Median relapse-free survival and overall survival were 6.7 and 7.1 months, respectively. The most frequent AEs were pyrexia (58%), febrile neutropenia (40%), and headache (31%). Three patients had cytokine release syndrome (all grade 1 or 2), and three patients had grade 3 neurologic events, one of which (aphasia) required temporary treatment interruption. There were no grade 4 or 5 neurologic events. Conclusion Single-agent blinatumomab showed antileukemia activity in high-risk patients with Ph⁺ ALL who had relapsed or were refractory to TKIs. AEs were consistent with previous experience in Ph^- ALL.

Growth of tyrosine kinase inhibitor-resistant Philadelphia-positive acute lymphoblastic leukemia: Role of bone marrow stromal cells

Human bone marrow stromal cells (hBMSCs) may contribute to the growth of tyrosine kinase inhibitor (TKI)-resistant chronic myelogenous leukemia (CML). However, there are certain differences in biology between CML and Philadelphia-positive acute lymphoblastic leukemia (Ph⁺ ALL). Little is known about the role and mechanism of hBMSCs on the growth of TKI-resistant Ph⁺ ALL. The current study co-cultured hBMSCs with the TKI-resistant SUP-B15. Next, the proliferation of SUP-B15 was detected using a Cell Counting Kit-8. Additionally, quantitative polymerase chain reaction and flow cytometry were used to detect the expression of the associated genes and proteins. The present study explores the role and mechanism of hBMSCs on the growth of TKI-resistant Ph⁺ ALL. The current study showed that hBMSCs promoted the proliferation of TKI-resistant Ph⁺ ALL. This was shown by the increase in cells in the S+G2-M phase of the cell cycle. It was also found that the expression of cyclins A, C, D1 and E was increased. Apoptosis was inhibited through upregulation of anti-apoptotic genes [B-cell lymphoma-2 (BCL-2) and BCL-extra large] and downregulation of apoptotic genes (BCL-XS, BCL-2-associated X protein, and caspases 3, 7 and 9). Expression of the breakpoint cluster region (BCR)-Abelson murine leukemia viral oncogene homolog 1 (ABL) gene, Wnt5a, and Wnt signaling pathway-associated genes (glycogen synthase kinase-3β, β-catenin, E-cadherin and phosphoinositide 3-kinase) and transcription factors (c-myc, ephrin type-B2, fibroblast growth factor 20 and matrix metalloproteinase 7) was also increased. Furthermore, the expression of drug resistance genes (low-density lipoprotein receptor, multidrug resistance-associated protein and multi-drug resistance gene) was increased and the expression of anti-oncogenes (death-associated protein kinase and interferon regulatory factor-1) was decreased. It was concluded that hBMSCs promote the growth of TKI-resistant Ph⁺ ALL by these aforementioned mechanisms. Therefore, targeting hBMSCs may be a promising approach for preventing the growth of TKI-resistant Ph⁺ ALL.

The targetable role of herpes virus-associated ubiquitin-specific protease (HAUSP) in p190 BCR-ABL leukemia

Philadelphia chromosome-positive (Ph⁺) acute lymphoblastic leukemia (ALL) is driven by the p190 breakpoint cluster region (BCR)-ABL isoform. Although effectively targeted by BCR-ABL tyrosine kinase inhibitors (TKIs), ALL is associated with a less effective response to TKIs compared with chronic myeloid leukemia. Therefore, the identification of additional genes required for ALL maintenance may provide possible therapeutic targets to aid the eradication of this cancer. The present study demonstrated that p190 BCR-ABL is able to interact with the deubiquitinase herpesvirus-associated ubiquitin-specific protease (HAUSP), which in turn affects p53 protein stability. Notably, the inhibition of HAUSP with small molecule inhibitors promoted the upregulation of p53 protein levels. These results suggest that HAUSP inhibitors may harbor clinically relevant implications in the treatment of Ph⁺ ALL.

Impact of complete molecular response on survival in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia

The impact of achieving complete molecular response (CMR) in Philadelphia chromosome-positive (Ph(+)) acute lymphoblastic leukemia (ALL) remains undefined. We evaluated the impact of CMR on outcomes among 85 patients with Ph(+) ALL who received first-line hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with methotrexate and high-dose cytarabine plus a tyrosine kinase inhibitor, had minimal residual disease (MRD) assessments for BCR-ABL1 by quantitative polymerase chain reaction at complete remission (CR) and at 3-month time points, and did not undergo allogeneic stem cell transplantation (SCT). MRD status at 3 months had better discrimination for overall survival (OS; P = .005) and relapse-free survival (RFS; P = .002) than did MRD status at CR (P = .11 and P = .04, respectively). At 3 months, achievement of CMR vs response less than CMR was associated with longer median OS (127 vs 38 months, respectively; P = .009) and RFS (126 vs 18 months, respectively; P = .007). By multivariate analysis, only CMR at 3 months was prognostic for OS (hazard ratio, 0.42; 95% confidence interval, 0.21-0.82; P = .01). Patients with Ph(+) ALL who achieve CMR at 3 months have superior survival compared with those with lesser molecular responses and have excellent long-term outcomes even without SCT.

Minimal Residual Disease Monitoring in Adult ALL to Determine Therapy

Almost 90 % of children and 50 % of adults with acute lymphoblastic leukemia (ALL) are cured by modern treatment regimens, with significant variations due to several disease- and host-related characteristics. The attainment of an early remission and the avoidance of relapse and treatment-related mortality are the fundamental therapeutic steps. In remission patients, the assessment of the disease response to early intensive therapy through the detection and monitoring of minimal residual disease (MRD) can accurately refine the individual prognosis and is increasingly used to support a risk-oriented treatment strategy. In this way, only the patients with an unfavorable MRD response are preferably selected for allogeneic stem cell transplantation, irrespective of their clinical risk class. This choice spares transplant-related toxicities to MRD responsive cases. Further advancement is expected by integrating the MRD analysis with improved pediatric-type regimens and novel targeting agents for ALL subsets at higher risk of relapse.

Protein Kinase CK2: A Targetable BCR-ABL Partner in Philadelphia Positive Leukemias

BCR-ABL-mediated leukemias, either Chronic Myeloid Leukemia (CML) or Philadelphia positive Acute Lymphoblastic Leukemia (ALL), are the paradigm of targeted molecular therapy of cancer due to the impressive clinical responses obtained with BCR-ABL specific tyrosine kinase inhibitors (TKIs). However, BCR-ABL TKIs do not allow completely eradicating both CML and ALL. Furthermore, ALL therapy is associated with much worse responses to TKIs than those observed in CML. The identification of additional pathways that mediate BCR-ABL leukemogenesis is indeed mandatory to achieve synthetic lethality together with TKI. Here, we review the role of BCR-ABL/protein kinase CK2 interaction in BCR-ABL leukemias, with potentially relevant implications for therapy.

DNA Repair--A Double-Edged Sword in the Genomic Stability of Cancer Cells--The Case of Chronic Myeloid Leukemia

Genomic instability is a common feature of cancer cells, which can result from aberrant DNA damage reaction (DDR). We and others showed that the well-known BCR-ABL1 fusion oncogene, the cause of chronic myeloid leukemia, induced an increased production of reactive oxygen species (ROS) and conferred therapeutic drug resistance by suppression of apoptotic signaling, prolonged G2/M arrest and stimulation of several pathways of DNA repair. However, to protect from apoptosis, cancer cells may tolerate some DNA lesions, which may increase genomic instability. Moreover, BCR/ABL1-stimulated DNA repair might be faulty, especially non-homologous end joining in its alternative forms. Normal DNA repair can remove DNA damage and prevent mutations, reducing genome instability, but on the other hand, due to its imprecise nature, it may increase genomic instability by increasing the ratio of mutagenic DNA lesions. The example of BCR-ABL1-expressing cells shows that DNA repair can both increase and decrease genomic instability of cancer cells and understanding the mechanism of the regulation of these opposite effects would be helpful in anticancer strategies.

Drugging the unfolded protein response in acute leukemias

The unfolded protein response (UPR), an endoplasmic reticulum (ER) stress-induced signaling cascade, is mediated by three major stress sensors IRE-1α, PERK, and ATF6α. Studies described the UPR as a critical network in selection, adaptation, and survival of cancer cells. While previous reviews focused mainly on solid cancer cells, in this review, we summarize the recent findings focusing on acute leukemias. We take into account the impact of the underlying genetic alterations of acute leukemia cells, the leukemia stem cell pool, and provide an outline on the current genetic, clinical, and therapeutic findings. Furthermore, we shed light on the important oncogene-specific regulation of individual UPR signaling branches and the therapeutic relevance of this information to answer the question if the UPR could be an attractive novel target in acute leukemias.

Impact of CYP2C8*3 polymorphism on in vitro metabolism of imatinib to N-desmethyl imatinib

1. Imatinib is metabolized to N-desmethyl imatinib by CYPs 3A4 and 2C8. The effect of CYP2C8*3 genotype on N-desmethyl imatinib formation was unknown. 2. We examined imatinib N-demethylation in human liver microsomes (HLMs) genotyped for CYP2C8*3, in CYP2C8*3/*3 pooled HLMs and in recombinant CYP2C8 and CYP3A4 enzymes. Effects of CYP-selective inhibitors on N-demethylation were also determined. 3. A single-enzyme Michaelis-Menten model with autoinhibition best fitted CYP2C8*1/*1 HLM (n = 5) and recombinant CYP2C8 kinetic data (median ± SD Ki = 139 ± 61 µM and 149 µM, respectively). Recombinant CYP3A4 showed two-site enzyme kinetics with no autoinhibition. Three of four CYP2C8*1/*3 HLMs showed single-enzyme kinetics with no autoinhibition. Binding affinity was higher in CYP2C8*1/*3 than CYP2C8*1/*1 HLM (median ± SD Km = 6 ± 2 versus 11 ± 2 µM, P=0.04). CYP2C8*3/*3 (pooled HLM) also showed high binding affinity (Km = 4 µM) and single-enzyme weak autoinhibition (Ki = 449 µM) kinetics. CYP2C8 inhibitors reduced HLM N-demethylation by 47-75%, compared to 0-30% for CYP3A4 inhibitors. 4. In conclusion, CYP2C8*3 is a gain-of-function polymorphism for imatinib N-demethylation, which appears to be mainly mediated by CYP2C8 and not CYP3A4 in vitro in HLM.

Prophylaxis and treatment of acute lymphoblastic leukemia relapse after allogeneic hematopoietic stem cell transplantation

Relapse of acute lymphoblastic leukemia remains a major cause of death in patients following allogeneic hematopoietic stem cell transplantation. Several factors may affect the concurrence and outcome of relapse, which include graft-versus-host disease, minimal residual disease or intrinsic factors of the disease, and transplantation characteristics. The mainstay of relapse prevention and treatment is donor leukocyte infusions, targeted therapies, second transplantation, and other novel therapies. In this review, we mainly focus on addressing the impact of graft-versus-host disease on relapse and the prophylaxis and treatment of acute lymphoblastic leukemia relapse following allogeneic hematopoietic stem cell transplantation. We also make recommendations for critical strategies to prevent relapse after transplantation and challenges that must be addressed to ensure success.

Modern immunotherapy of adult B-lineage acute lymphoblastic leukemia with monoclonal antibodies and chimeric antigen receptor modified T cells

The introduction of newer cytotoxic monoclonal antibodies and chimeric antigen receptor modified T cells is opening a new age in the management of B-lineage adult acute lymphoblastic leukemia. This therapeutic change must be very positively acknowledged because of the limits of intensive chemotherapy programs and allogeneic stem cell transplantation. In fact, with these traditional therapeutic tools the cure can be achieved in only 40-50% of the patients. The failure rates are particularly high in the elderly, in patients with post-induction persistence of minimal residual disease and especially in refractory/relapsed disease. The place of the novel immunotherapeutics in improving the outcome of adult patients with B-lineage acute lymphoblastic leukemia is reviewed.

Prognostic impact of minimal residual disease in adult acute lymphoblastic leukemia

SUMMARY 

While adult acute lymphoblastic leukemia (ALL) is curable in 40–50% of the patients, the individual prognosis is rather unpredictable due to associated biological and clinical risk factors. In both B- and T-precursor ALL, minimal residual disease (MRD) represents the most sensitive prognostic marker, useful to support critical treatment decisions, ranging from allogeneic stem cell transplantation in patients with inadequate MRD response to chemotherapy only in MRD responsive ones. This optimized risk-adapted strategy allows to spare transplant-associated morbidity and mortality in patients curable by chemotherapy. Further progress is expected from the integration of the MRD-based strategy with improved pediatric-type regimens and novel targeting agents for discrete ALL subsets. These changes are increasing the cure rate to above 50%.