Current Treatment of Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia

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.

Current treatment strategies for Philadelphia chromosome-positive adult acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is an aggressive hematological disease. The incorporation of tyrosine kinase inhibitors (TKIs) into the standard treatment regimen for Philadelphia (Ph)-positive ALL significantly improved clinical outcomes. TKI-based induction chemotherapy, followed by allogeneic hematopoietic cell transplantation (HCT) during the first complete remission (CR), is the standard of care for ALL patients. However, treatment with TKIs alone or TKIs plus low-intensity chemotherapy can achieve CR in some patients. Although this strategy is not enough to induce a deeper molecular response, it can reduce the incidence of treatment-related mortality. Despite promising results from pediatric trials, allogeneic HCT remains an important component of the treatment strategy for Ph-positive adult ALL. However, improving the highly sensitive BCR-ABL1 assays and introducing immunotherapy may decrease the demand for allogeneic HCT. Nevertheless, the treatment of Ph-positive ALL is still challenging, especially in cases with relapsed and refractory disease. Potent TKIs and monoclonal antibodies, such as blinatumomab and inotuzumab, have improved patient outcomes in relapse and refractory cases of ALL. The introduction of effective agents, such as potent TKIs and monoclonal antibodies, may improve the possibility of remission in Ph-positive ALL patients and hopefully cure this disease.

Ponatinib therapy in recurrent Philadelphia chromosome-positive central nervous system leukemia with T315I mutation after Allo-HSCT

Central nervous system leukemia (CNSL) relapse is relatively common among Philadelphia chromosome-positive (Ph+) leukemia patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). The prognosis of patients is dismal for those with a BCR-ABL T315I mutation, which is resistant to TKIs including second-generation drugs. We assessed ponatinib for nine patients with recurrent Ph+ CNSL and a T315I mutation after allo-HSCT, including five patients with Ph+ acute lymphoblastic leukemia and four with chronic myelogenous leukemia. Five patients experienced isolated CNSL relapse, and four experienced CNSL with hematologic relapse. All patients received ponatinib combined with intrathecal chemotherapy, and four patients with hematologic relapse received systemic chemotherapy and/or donor lymphocyte infusion. All patients achieved a deep molecular response and central nervous system remission (CNSR) at a median time of 1.5 (range: 0.7-3) months after ponatinib treatment. Two patients experienced a second CNSL relapse due to ponatinib reduction, but they achieved CNSR again after an increase to the standard dosage. Six patients developed graft versus host disease. By April 1, 2019, eight patients were alive, and one died of pneumonia. The median time of survival after the first CNSL relapse posttransplantation was 18 (range: 11.2-48.5) months. Our data from a small number of samples suggests that ponatinib is effective for recurrent Ph+ CNSL patients with a BCR-ABL T315I mutation after allo-HSCT and warrants broader clinical evaluation.

Curing Ph+ ALL: assessing the relative contributions of chemotherapy, TKIs, and allogeneic stem cell transplant

The understanding and treatment of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia have changed rapidly in the past 10 years. The outcome is equally as good as for Ph- disease, and with targeted tyrosine kinase inhibitor therapies in addition to chemotherapy, the novel immunotherapy approaches, and the extension of allogeneic hematopoietic stem cell transplant (allo-HCT) to older individuals, there is the potential to exceed this outcome. There is particular interest in reducing chemotherapy exposure and considering for whom allo-HCT can be avoided. However, the patient population that can help test these options in clinical trials is limited in number, and the available evidence is often derived from single-arm studies. This paper summarizes outcomes achieved with recent approaches to de novo Ph+ acute lymphoblastic leukemia in the postimatinib era and helps integrate all the available information to assist the reader to make informed choices for patients in an increasingly complex field.

A systematic literature review and meta-analysis of minimal residual disease as a prognostic indicator in adult B-cell acute lymphoblastic leukemia

Minimal (or 'measurable') residual disease in acute lymphoblastic leukemia appears to be a prognostic indicator, with potential value in informing individualized treatment decisions. Complete understanding of the strength of the association between minimal residual disease and long-term outcomes is, however, lacking. A systematic literature review and meta-analysis were performed to elucidate the clinical significance of minimal residual disease with respect to relapse-free survival and overall survival in precursor B-cell acute lymphoblastic leukemia. A total of 23 articles and abstracts, most published between 2012 and 2016, were identified for inclusion in the primary meta-analysis. Typically, patients were in their first complete remission at the time of minimal residual disease assessment; in two studies, all patients were in their second, or later, complete remission. The primary analysis revealed improved relapse-free survival across all studies for patients who achieved minimal residual disease negativity (random effects hazard ratio, 2.34; 95% confidence interval, 1.91-2.86). Improved overall survival for patients who achieved minimal residual disease negativity was also observed (hazard ratio, 2.19; 95% confidence interval, 1.63-2.94). There was no observed difference in the impact of minimal residual disease status in subgroups based on disease stage, minimal residual disease sensitivity threshold level, Philadelphia chromosome status, histological phenotype, risk group, minimal residual disease testing location, minimal residual disease timing after induction, or minimal residual disease detection method. Despite heterogeneity in study design and patient populations between the contributing studies, these data provide a compelling argument for minimal residual disease as a clinical tool for assessing prognosis and guiding treatment decisions in precursor B-cell acute lymphoblastic leukemia.

ABL1 tyrosine kinase domain mutations in chronic myeloid leukemia treatment resistance

The development of mutations in the BCR-ABL1 fusion gene transcript causes resistance to tyrosine kinase inhibitors (TKIs) based therapy in chronic myeloid leukemia (CML). Thereby, screening for BCR-ABL1 mutations is advised especially in patients undergoing poor response to treatment. In the current study the authors investigated 43 patients with CML that failed or had suboptimal response to TKIs treatment. Blood samples were collected from patients that were treated with TKIs. The analysis of genetic mutations was performed using a semi-nested PCR assay, followed by Sanger sequencing. The analysis revealed 15 mutations (32.55%): 14 point mutations and an exon 7 deletion. In roughly 30% of cases, mutations in the BCR-ABL1 fusion gene are common causes for treatment resistance.

Ponatinib for Treating Acute Lymphoblastic Leukaemia: An Evidence Review Group Perspective of a NICE Single Technology Appraisal

As part of its single technology appraisal (STA) process, the UK National Institute for Health and Care Excellence (NICE) invited the manufacturer (Incyte Corporation) of ponatinib (Inclusig^®) to submit evidence of its clinical and cost effectiveness for previously treated Philadelphia-chromosome-positive acute lymphoblastic leukaemia (Ph+ ALL) and chronic myeloid leukaemia. This paper focusses on Ph+ ALL. The School of Health and Related Research Technology Appraisal Group at the University of Sheffield was commissioned to act as the independent evidence review group (ERG). This article presents the critical review of the company's submission by the ERG and the outcome of the NICE guidance. The clinical-effectiveness evidence in the company's submission was derived from a phase II, single-arm, open-label, non-comparative study. Given the lack of comparative evidence, a naïve indirect comparison was performed against re-induction chemotherapy comparing major cytogenetic response and complete remission. Best supportive care (BSC) was assumed to produce no disease response. Despite the limited evidence and potential for biases, this study demonstrated that ponatinib was likely to be an effective treatment for patients with Ph+ ALL. The company submitted a state transition model that analysed the incremental cost effectiveness of ponatinib versus re-induction therapy and BSC for the treatment of Ph+ ALL in patients whose disease is resistant to dasatinib, who are intolerant to dasatinib and for whom subsequent treatment with imatinib is not clinically appropriate or who have the threonine-315-isoleucine mutation. This population was further subdivided into those who were suitable for allogeneic stem cell transplant (allo-SCT) and those who were not. The company's revised economic evaluation, following the clarification process, estimated incremental cost-effectiveness ratios (ICERs) in those suitable for allo-SCT of £31,123 per quality-adjusted life-year (QALY) gained for ponatinib compared with re-induction chemotherapy and £26,624 per QALY gained compared with BSC. For those for whom allo-SCT was unsuitable, the company-estimated ICER compared with BSC was £33,954 per QALY gained. Following a critique of the model, the ERG undertook exploratory analyses that, when combined, produced a range in ICERs (due to uncertainty of the most appropriate overall survival function) of dominant (being less expensive and providing more QALYs) to £11,727 per QALY gained compared with re-induction chemotherapy and between £7892 and £31,696 per QALY gained compared with BSC for those in whom allo-SCT was suitable. For those in whom allo-SCT was not suitable, the ERG estimated that ponatinib was dominant. During the consultation period, the company agreed a revised patient access scheme (PAS) that reduced the ICER ranges to £7156 to £29,995 per QALY gained versus BSC and to less than £5000 per QALY gained versus re-induction chemotherapy. In people for whom allo-SCT was unsuitable, ponatinib dominated BSC. The NICE appraisal committee concluded that ponatinib is a cost-effective use of UK NHS resources in the considered population, subject to the company providing the agreed discount in the PAS.

Efficacy and safety of autologous peripheral blood stem cell transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia: A study protocol for a multicenter exploratory prospective study (Auto-Ph17 study)

INTRODUCTION

The prognosis of Philadelphia chromosome positive acute lymphoblastic leukemia (Ph + ALL) has been dramatically improved since the introduction of tyrosine kinase inhibitors (TKIs). Although allogeneic hematopoietic cell transplantation (allo-HCT) is a major treatment option, the role of autologous peripheral blood stem cell transplantation (auto-PBSCT) has been reconsidered, especially in patients who achieved early molecular remission.

METHODS AND ANALYSIS

This is a multicenter exploratory study for Ph + ALL patients aged between 55 and 70 years who achieved complete molecular remission within 3 cycles of chemotherapy. The target sample size is 5, and the registration period is 2 years. The primary endpoint is Day100- mortality after transplantation, and the secondary endpoints are survival, relapse rate, nonrelapse mortality, and adverse events.This study is divided into 3 phases: peripheral blood stem cell harvest, transplantation, and maintenance. Chemomobilization is performed using a combination of cyclophosphamide (CPM), doxorubicin, vincristine (VCR), and prednisolone (PSL). As a preparative regimen, the LEED regimen is used, which consists of melphalan, CPM, etoposide, and dexamethasone. Twelve cycles of maintenance therapy using a combination of VCR, PSL, and dasatinib are performed.In association with relapse, the minimal residual disease (MRD) of BCR-ABL chimeric gene and T-cell subsets are analyzed both before and after auto-PBSCT.

ETHICS AND DISSEMINATION

The protocol was approved by the institutional review board of Nagoya University Hospital and all the participating hospitals. Written informed consent was obtained from all patients before registration, in accordance with the Declaration of Helsinki. Results of the study will be disseminated via publications in peer-reviewed journals.

TRIAL REGISTRATION

Trial registration number UMIN000026445.

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.

Cancer Drug Delivery

Advancements in cancer drug delivery have led to the development of personalized oncology care through molecularly-driven targeted therapies. Understanding molecular and cellular mechanisms which drive tumor progression and resistance is critical in managing new treatment strategies which have shifted from empiric to biomarker-directed therapy selection. Biomarker-directed therapies have improved clinical outcomes in multiple malignancies as monotherapy and in combination with other treatment modalities, however the changing scope of treatment options presents new opportunities and challenges for research. Furthermore, pharmacogenetics may provide a rationale method of personalizing anticancer drug dosing and supportive care management for oncology patients. This chapter reviews biomarker classifications and pharmacogenetics in anticancer therapy and supportive care. Examples of biomarker-directed therapies and clinical assays, in addition to future directions of molecular profiling in oncology therapy management are discussed.

Effects of plant-derived anti-leukemic drugs on individualized leukemic cell population profiles in Egyptian patients

Leukemias are a group of cancer types that originate from blood-forming tissues. In this disease, an abnormally large number of immature white blood cells is produced by the bone marrow. The relationship between treatments with plant-derived drugs and leukemia-associated immunophenotypes (LAIPs) of clinically isolated leukemia cells has yet to be established. The aim of the present study was to develop a preliminary clinical prognostic map for commonly expressed LAIPs in patients clinically diagnosed with leukemia, as well as to assess the potential involvement of LAIPs in the response rate to 10 natural products of plant origin. An increased expression of LAIPs, including CD4, CD14, CD33 and CD34, was considered a surrogate marker of the desired response of leukemia cells to treatment with plant-derived drugs. By contrast, the increased expression of the LAIPs, MPO and DR, was associated with poor prognostic outcomes following treatment with the plant-derived drugs. The results showed that 5 of the 10 plant-derived drugs tested induced the expression of several desirable LAIPs biomarkers. These findings clearly highlight the potential treatment efficacy of certain plant-derived drugs against leukemic cell types.

Impact of MRD and TKI on allogeneic hematopoietic cell transplantation for Ph+ALL: a study from the adult ALL WG of the JSHCT

To assess the impact of minimal residual disease (MRD) and tyrosine kinase inhibitor (TKI) administration on allogeneic hematopoietic cell transplantation (allo-HCT) for Ph-positive ALL (Ph+ALL), we retrospectively analyzed data from a registry database for 432 adult Ph+ALL patients in first CR (CR1) who received pre-transplant TKI administration. Negative MRD (MRD(-)) at allo-HCT was achieved in 277 patients. OS in patients transplanted in MRD(-) was significantly better than that in patients transplanted in MRD(+) (MRD(-): 67% vs MRD(+): 55% at 4 years; P=0.001). MRD(-) at allo-HCT was a significant risk factor for survival along with age at allo-HCT in multivariate analyses. Incidence of relapse in patients transplanted in MRD(-) was significantly lower than that in patients transplanted in MRD(+) (MRD(-): 19% vs MRD(+): 29% at 4 years; P=0.006). In multivariate analyses, MRD(+) at allo-HCT was a significant risk factor for relapse. A post-transplant TKI was administered to 103 patients. In subanalyses regarding the effect of post-transplant TKI administration, post-transplant TKI administration was a significant risk factor for relapse in multivariate analyses (P<0.0001). MRD status at allo-HCT is one of the most important predictive factors for Ph+ALL patients transplanted in CR1.

Ribavirin Inhibits the Activity of mTOR/eIF4E, ERK/Mnk1/eIF4E Signaling Pathway and Synergizes with Tyrosine Kinase Inhibitor Imatinib to Impair Bcr-Abl Mediated Proliferation and Apoptosis in Ph+ Leukemia

The eukaryotic translation initiation factor 4E (eIF4E), which is the main composition factor of eIF4F translation initiation complex, influences the growth of tumor through modulating cap-dependent protein translation. Previous studies reported that ribavirin could suppress eIF4E-controlled translation and reduce the synthesis of onco-proteins. Here, we investigated the anti-leukemic effects of ribavirin alone or in combination with tyrosine kinase inhibitor imatinib in Philadelphia chromosome positive (Ph+) leukemia cell lines SUP-B15 (Ph+ acute lymphoblastic leukemia cell line, Ph+ ALL) and K562 (chronic myelogenous leukemia cell line, CML). Our results showed that ribavirin had anti-proliferation effect; it down-regulated the phosphorylation levels of Akt, mTOR, 4EBP1, and eIF4E proteins in the mTOR/eIF4E signaling pathway, and MEK, ERK, Mnk1 and eIF4E proteins in ERK/Mnk1/eIF4E signaling pathway; reduced the expression of Mcl-1 (a translation substrates of eIF4F translation initiation complex) at protein synthesis level not mRNA transcriptional level; and induced cell apoptosis in both SUP-B15 and K562. 7-Methyl-guanosine cap affinity assay further demonstrated that ribavirin remarkably increased the eIF4E binding to 4EBP1 and decreased the combination of eIF4E with eIF4G, consequently resulting in a major inhibition of eIF4F complex assembly. The combination of ribavirin with imatinib enhanced antileukemic effects mentioned above, indicating that two drugs have synergistic anti-leukemic effect. Consistent with the cell lines, similar results were observed in Ph+ acute lymphoblastic primary leukemic blasts; however, the anti-proliferative role of ribavirin in other types of acute primary leukemic blasts was not obvious, which indicated that the anti-leukemic effect of ribavirin was different in cell lineages.

Long-term follow-up of a phase 2 study of chemotherapy plus dasatinib for the initial treatment of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia

BACKGROUND

The long-term efficacy of a combination of chemotherapy and dasatinib in patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) is not well established.

METHODS

Patients received dasatinib with 8 cycles of alternating hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone and high-dose cytarabine and methotrexate. Patients in complete remission (CR) continued maintenance dasatinib, vincristine, and prednisone for 2 years, which was followed by dasatinib indefinitely. Patients eligible for allogeneic stem cell transplantation (SCT) received it during their first CR.

RESULTS

Seventy-two patients with a median age of 55 years (range, 21-80 years) were treated; 69 (96%) achieved CR. Among them, 57 (83%) achieved cytogenetic CR after 1 cycle, and 64 (93%) achieved a major molecular response at a median of 4 weeks (range, 2-38 weeks). Sixty-five patients (94%) were negative for minimal residual disease assessed by flow cytometry at a median of 3 weeks (range, 2-37 weeks). Dasatinib-related grade 3 and 4 adverse events included bleeding, pleural/pericardial effusions, and elevated transaminases. With a median follow-up of 67 months (range, 33-97 months), 33 patients (46%) were alive, and 30 (43%) were in CR; 12 underwent allogeneic SCT. Thirty-nine patients died (3 at induction, 19 after relapse, 7 after SCT performed during first CR, and 10 during CR). The median disease-free survival and overall survival were 31 (range, 0.3-97 months) and 47 months (range, 0.2-97 months), respectively. Seven relapsed patients had BCR-ABL kinase domain mutations, including 4 with T315I.

CONCLUSIONS

A combination of chemotherapy with dasatinib is effective in achieving long-term remission for patients with newly diagnosed Ph + ALL.

[Effects of stromal cells on sentitivity to imatinib in Sup-B15 Philadelphia chromosome positive acute lymphoblastic leukemia cells]

目的

探讨基质细胞OP9能否影响Ph⁺急性淋巴细胞白血病细胞株Sup-B15细胞对伊马替尼的敏感性以及作用机制。

方法

实验分为Sup-B15细胞组及基质细胞OP9与Sup-B15共培养组（即Sup-B15/OP9组）。采用CCK-8法测定细胞增殖抑制率；流式细胞术检测Annexin V/7-AAD标记的细胞凋亡率、CD34⁺CD38⁻细胞比例；荧光定量PCR检测细胞ALDH1、CD144、β-catenin mRNA水平；Western blot法检测细胞CD133、CD144、β-catenin蛋白表达水平；免疫共沉淀方法检测结合于CD144的β-catenin水平。

结果

10~45 µmol/L伊马替尼对Sup-B15、Sup-B15/OP9细胞均有增殖抑制作用，其IC₅₀值分别为26.3和35.8 µmol/L，两组差异有统计学意义（P<0.05）。30 µmol/L伊马替尼作用于Sup-B15、Sup-B15/OP9细胞24 h，细胞总凋亡率分别为（14.24±2.11）%和（3.45±0.68）%，两组差异有统计学意义（P<0.05）。与Sup-B15组相比，Sup-B15/OP9组CD34⁺CD38⁻细胞比例增高[（3.42±0.28）%对（2.16±0.15）%，P<0.05]，ALDH1 mRNA水平增高（0.097±0.012对0.046±0.010，P<0.05），CD133蛋白表达水平升高；CD144 mRNA水平增高（0.103±0.015对0.010±0.003，P<0.05），CD144蛋白表达水平亦明显增高；β-catenin mRNA水平无明显变化（P>0.05），其蛋白总量明显上升，转位到细胞核的β-catenin蛋白明显增加，结合于CD144的β-catenin蛋白增加。

结论

与OP9细胞共培养后，Sup-B15细胞对伊马替尼敏感性下降，该作用可能与上调CD144表达、稳定CD144 /β-catenin信号通路、增加β-catenin核转位有关。

From the Biology of PP2A to the PADs for Therapy of Hematologic Malignancies

Over the past decades, an emerging role of phosphatases in the pathogenesis of hematologic malignancies and solid tumors has been established. The tumor-suppressor protein phosphatase 2A (PP2A) belongs to the serine-threonine phosphatases family and accounts for the majority of serine-threonine phosphatase activity in eukaryotic cells. Numerous studies have shown that inhibition of PP2A expression and/or function may contribute to leukemogenesis in several hematological malignancies. Likewise, overexpression or aberrant expression of physiologic PP2A inhibitory molecules (e.g., SET and its associated SETBP1 and CIP2A) may turn off PP2A function and participate to leukemic progression. The discovery of PP2A as tumor suppressor has prompted the evaluation of the safety and the efficacy of new compounds, which can restore PP2A activity in leukemic cells. Although further studies are needed to better understand how PP2A acts in the intricate phosphatases/kinases cancer network, the results reviewed herein strongly support the development on new PP2A-activating drugs and the immediate introduction of those available into clinical protocols for leukemia patients refractory or resistant to current available therapies.

Stromal cells attenuate the cytotoxicity of imatinib on Philadelphia chromosome-positive leukemia cells by up-regulating the VE-cadherin/β-catenin signal

β-Catenin is a key regulator of leukemia stem cell maintenance and drug resistance. Herein, we investigated the protective effects of the stromal cell-mediated VE-cadherin-β-catenin signal on Ph+ leukemia cells during imatinib treatment. We found stromal cells could desensitize imatinib and up-regulate VE-cadherin expression on Ph+ leukemia cells (K562 and SUP-B15 cells), which further stabilized and activated β-catenin. Knockdown of VE-cadherin with shRNA diminished the β-catenin protein and partly resensitized Ph+ leukemia cells to imatinib despite the presence of stromal cells, suggesting VE-cadherin is a potential target in the treatment of Ph+ leukemia.

Outcome after HSCT in Philadelphia chromosome positive acute lymphoblastic leukemia in Sweden: a population-based study

Even in the tyrosine kinase inhibitor era, allogeneic hematopoietic stem cell transplantation (HSCT) is regarded as standard care for adult Philadelphia (Ph) positive acute lymphoblastic leukemia (ALL). In this retrospective national study, we have reviewed the outcome after HSCT in Sweden for adult Ph-positive ALL between 2000 and 2009. In total, 51 patients with median age 42 (range 20-66) years underwent HSCT. Mainly allogeneic HSCT was performed (24 related donor, 24 unrelated donor and one cord blood), and only two patients were treated with an autologous HSCT. The 5-year OS was 51 (37-64) %. The probabilities of morphological relapse and non-relapse mortality (NRM) at 5 years were 36 (23-49) and 18 (9-29) %, respectively. For the allogeneic transplanted, the 5-year OS was for patients <40 years 70 (50-90) % and for patients ≥40 years 34 (16-52) %, p = 0.002. The 5-year probability of NRM was for patients <40 years 10 (2-28) % compared to 25 (11-42) % for patients ≥40 years (p = 0.04). Patients with chronic graft-versus-host disease (GVHD) had a 5-year morphological relapse probability of 20 (6-40) % compared to 59 (35-77) % for patients without chronic GVHD (p = 0.03). Age ≥40 years and the absence of chronic GVHD were confirmed as independent negative prognostic factors for relapse and non-relapse mortality in a multivariate analysis although the impact of chronic GVHD was significant only in the older age cohort.

Prognostic significance of monitoring leukemia-associated immunophenotypes by eight-color flow cytometry in adult B-acute lymphoblastic leukemia

Minimal residual disease (MRD) is of the most important factor for predicting prognosis and guiding treatment of acute lymphoblastic leukemia (ALL). In this study, we investigated the prognostic significance of leukemia-associated immunophenotypes (LAIPs) as assessment of index of MRD in 125 adult B-lineage ALL (B-ALL) patients by eight-color flow cytometry. The LAIPs could be identified in 96% and 81.6% of patients with the sensitivity of 10(-4) and 10(-5), respectively. MRD-negative status could clearly predict a favorable 2-year relapse-free survival (RFS) and overall survival (OS) at the end of induction of complete remission and one cycle of consolidation treatment. Moreover, we identified a group of cases with MRD of 0.001% to <0.01%, which showed significantly higher 2-year relapse rate than those with undetectable one. In multivariate analysis, MRD status was associated with RFS or OS independently. Furthermore, MRD assessed by LAIPs and RQ-PCR assay for patients with BCR-ABL fusion gene yielded concordant results in 89.7% of cases. In conclusion, MRD evaluated by eight-color flow cytometry could provide an important tool to assess treatment response and prognosis precisely in adult B-ALL.

Detection of MRD may predict the outcome of patients with Philadelphia chromosome-positive ALL treated with tyrosine kinase inhibitors plus chemotherapy

From 2001 to 2011, 122 patients with newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia were treated with chemotherapy + imatinib (n = 54) or + dasatinib (n = 68). One hundred fifteen (94%) achieved complete remission (CR) including 101 patients who achieved it with only 1 induction course and had at least 1 minimal residual disease (MRD) assessment; 25 patients underwent an allogeneic stem cell transplant in first CR and were excluded, leaving 76 patients as the subject of this report. MRD monitoring by multiparameter flow cytometry (MFC) and real-time quantitative polymerase chain reaction (PCR) was performed at the end of induction and at ~3-month intervals thereafter. Median age was 54 years (range, 21-84 years). There was no difference in survival by achievement of at least a major molecular response (MMR; BCR-ABL/ABL < 0.1%) at CR (P = .22). Patients achieving MMR at 3, 6, 9, and 12 months had a better survival (P = .02, .04, .05, and .01, respectively). Negative MFC at CR did not predict for improved survival (P = .2). At 3 and 12 months, negative MRD by MFC was associated with improved survival (P = .04 and .001). MRD monitoring by PCR and MFC identifies patients who benefit from treatment intensification in first CR.

Clinically relevant cancer biomarkers and pharmacogenetic assays

BACKGROUND

The number of pharmacogenetic assays available is continuously expanding as more molecularly targeted anticancer drugs are under clinical development. While the literature regarding drug-gene associations and therapeutic implications is often robust, reviews regarding clinical assay availability and profiling methodologies of commonly used cancer biomarkers are often lacking.

OBJECTIVE

To concisely identify and describe cancer biomarkers and their respective pharmacogenetic assays currently available in clinical practice.

DISCUSSION

Analysis of germ-line DNA mutations can often help to predict pharmacokinetic and pharmacodynamic responses, whereas somatic DNA mutations are particularly useful in predicting tumor response. Molecular profiling and pre-emptive identification of cancer biomarkers can help to predict disease prognosis as well as response to anticancer therapy. Dozens of pharmacogenetic assays, utilizing several common methodologies, are currently available in clinical practice. It is essential for clinicians to understand the molecular pathways for anticancer drugs, the therapeutic implications of mutations within these pathways, the clinical assay(s) available to test for pharmacogenetic differences, and the common profiling methodology employed.

CONCLUSION

As research continues to unveil more drug-gene and disease-gene associations, it is critical that clinicians understand which pharmacogenetic assays are available to identify inter-individual differences that predict safety and efficacy of anticancer drugs as we move toward the concept of personalized medicine.

Has MRD monitoring superseded other prognostic factors in adult ALL?

Significant improvements have been made in the treatment of acute lymphoblastic leukemia (ALL) during the past 2 decades, and measurement of submicroscopic (minimal) levels of residual disease (MRD) is increasingly used to monitor treatment efficacy. For a better comparability of MRD data, there are ongoing efforts to standardize MRD quantification using real-time quantitative PCR of clonal immunoglobulin and T-cell receptor gene rearrangements, real-time quantitative-based detection of fusion gene transcripts or breakpoints, and multiparameter flow cytometric immunophenotyping. Several studies have demonstrated that MRD assessment in childhood and adult ALL significantly correlates with clinical outcome. MRD detection is particularly useful for evaluation of treatment response, but also for early assessment of an impending relapse. Therefore, MRD has gained a prominent position in many ALL treatment studies as a tool for tailoring therapy with growing evidence that MRD supersedes most conventional stratification criteria at least for Ph-negative ALL. Most study protocols on adult ALL follow a 2-step approach with a first classic pretherapeutic and a second MRD-based risk stratification. Here we discuss whether and how MRD is ready to be used as main decisive marker and whether pretherapeutic factors and MRD are really competing or complementary tools to individualize treatment.

Optimal approach to treatment of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia: how to best use all the available tools

Approximately 20% of adult and 50% of elderly patients with acute lymphoblastic leukemia (ALL) express the t(9;22) chromosome translocation with BCR-ABL rearrangement. The use of tyrosine kinase inhibitors (TKIs) has resulted in higher rates of complete remission (95-100%), and many fit patients are able to receive allogeneic hematopoietic stem cell transplant (HSCT). TKI-containing induction followed by myeloablative allogeneic HSCT has resulted in long-term survival between 50 and 60% in young adults, and recent reports show promising results in patients submitted to non-myeloablative HSCT. The prognosis of elderly patients with Philadelphia chromosome-positive (Ph+) ALL is poor despite a high complete remission (CR) rate with TKIs and minimal chemotherapy, and improvements are clearly needed in this subgroup of patients. This review summarizes and discusses current challenges in the treatment of patients with Ph+ ALL, such as selection of the appropriate induction therapy, minimization of transplant toxicity, correct use of TKIs after transplant, BCR-ABL monitoring, the study of mutations which confer resistance to TKIs and new drugs to overcome this resistance.

Tyrosine kinase inhibitors in acute and chronic leukemias

INTRODUCTION

Since the initial approval of imatinib much has been learned about its resistance mechanisms, and efforts have continued to improve upon BCR-ABL tyrosine kinase inhibitor therapy. Targeted therapy with TKIs has continued to be an area of active research and development in the care of acute and chronic leukemia patients.

AREAS COVERED

This article reviews current approved and investigational TKI treatments for chronic myelogenous leukemia (CML), Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph + ALL) and acute myelogenous leukemia (AML).

EXPERT OPINION

There are now more potent BCR-ABL TKIs approved, which allow for additional options when determining front-line and second-line CML and Ph + ALL treatments. The T315I mutation is an ever-present challenge. Ponatinib, a pan BCR-ABL TKI, while still under investigation, is very hopeful with its ability to overcome T315I mutations in resistant CML and Ph + ALL patients. Because nilotinib and dasatinib have not been directly compared, at present we recommend selecting one or the other based on the side-effect profile, drug interactions, patient comorbidities, and mutational status. FLT-3 inhibition is of particular interest in AML patients with FLT-3 internal tandem duplication mutations; this type of targeted therapy continues to be studied.