Novel Therapeutics in Acute Myeloid Leukemia

TAS4464, a NEDD8-activating enzyme inhibitor, activates both intrinsic and extrinsic apoptotic pathways via c-Myc-mediated regulation in acute myeloid leukemia

TAS4464, a potent, selective small molecule NEDD8-activating enzyme (NAE) inhibitor, leads to inactivation of cullin-RING E3 ubiquitin ligases (CRLs) and consequent accumulations of its substrate proteins. Here, we investigated the antitumor properties and action mechanism of TAS4464 in acute myeloid leukemia (AML). TAS4464 induced apoptotic cell death in various AML cell lines. TAS4464 treatments resulted in the activation of both the caspase-9-mediated intrinsic apoptotic pathway and caspase-8-mediated extrinsic apoptotic pathway in AML cells; combined treatment with inhibitors of these caspases markedly diminished TAS4464-induced apoptosis. In each apoptotic pathway, TAS4464 induced the mRNA transcription of the intrinsic proapoptotic factor NOXA and decreased that of the extrinsic antiapoptotic factor c-FLIP. RNA-sequencing analysis showed that the signaling pathway of the CRL substrate c-Myc was enriched after TAS4464 treatment. Chromatin immunoprecipitation (ChIP) assay revealed that TAS4464-induced c-Myc bound to the PMAIP1 (encoding NOXA) and CFLAR (encoding c-FLIP) promoter regions, and siRNA-mediated c-Myc knockdown neutralized both TAS4464-mediated NOXA induction and c-FLIP downregulation. TAS4464 activated both caspase-8 and caspase-9 along with an increase in NOXA and a decrease in c-FLIP, resulting in complete tumor remission in a human AML xenograft model. These findings suggest that NAE inhibition leads to anti-AML activity via a novel c-Myc-dependent apoptosis induction mechanism.

Role of hepatitis B antibody in predicting reactivation of resolved hepatitis B virus infection in leukemia patients

BACKGROUND & AIMS

Quantification of anti-HBs and anti-HBc predicts the risk of HBV reactivation (HBVr) in lymphoma patients receiving rituximab treatment. However, it remains unclear whether the quantification is predictive of HBVr in leukemia patients undergoing immunosuppression.

METHODS

and patients: Clinical and laboratory data of the leukemia patients with resolved HBV infection diagnosed between January 2013 and March 2018 were retrospectively collected. Data series of HBV seromarkers and HBV DNA levels before the patients receiving chemotherapy and/or hematopoietic stem cell transplantation (HSCT) and during follow-up duration were analyzed.

RESULTS

In total, 533 leukemia patients with resolved HBV infection were included. The incidences of HBVr were 5.7% (25/441) and 2.2% (2/92) in patients receiving HSCT and chemotherapy, respectively. In patients receiving HSCT, acute lymphoid leukemia had a significantly higher incidence of HBVr than acute myeloid leukemia (8.9% vs 3.9%, P < 0.05). The incidence varied almost zero to 40% due to the differences in the profiles of HBV antibodies. High anti-HBs (cut-off of 79.2 IU/L) or low anti-HBc levels (cut-off of 4.475, S/CO) at baseline were associated with a low risk of HBVr. Anti-HBe status did not affect the incidence of HBVr. However, the cut-offs were only predictive of HBVr in the patients who had negative anti-HBe.

CONCLUSION

The baseline profiles of HBV antibodies are predictive of the risk of HBVr in leukemia patients undergoing immunosuppression. However, seronegative anti-HBe is a prerequisite for using baseline anti-HBs and anti-HBc quantification to predict HBVr risk.

Reinforcing the primary immunotherapy modulators against acute leukemia; monoclonal antibodies in AML

Recent therapeutic advances in cancer treatment recruit immune system potentiation against malignant cells. Numerous ongoing clinical trials on immunotherapy methods, either monotherapy or combination therapy, are investigating the impeding factors on the way of acute myeloid leukemia (AML) treatment. Due to the genetic diversity in AML progenitors, combining various strategies is more likely to be useful for improving patient outcomes. This review describes the details of applying monoclonal antibodies against AML, focusing on CD33, CD123, FLT3, CD45 and CD66 targeting. Furthermore, it clarifies the importance of immunotoxins, bispecific antibodies, chimeric antigen receptor (CAR)-T cells and T cell receptor-modified cells as reinforcing agents for monoclonal antibodies.

Myeloid Sarcoma: Presentation, Diagnosis, and Treatment

Myeloid sarcoma is an extramedullary tumor of immature granulocytic cells. It is a rare condition, most often associated with acute myeloid leukemia (AML), although in some rare cases it may present in nonleukemic patients. It should therefore be considered as a differential diagnosis of any atypical cellular infiltrate. It may occur at any site, leading to very varied clinical presentations. Diagnosis is challenging and relies on a high index of suspicion as well as radiology, histology, immunophenotyping, and molecular analyses, which also are essential for risk stratification and treatment planning. Systemic chemotherapy using AML-like regimens should be commenced early, even in nonleukemic disease. Surgery and/or radiotherapy may be indicated for symptomatic lesions or tumors causing local organ dysfunction or obstruction. Allogeneic hematopoietic stem cell transplantation has demonstrated promising results, particularly in patients who achieved complete remission with AML-induction protocols, and recent advances in genetic profiling may enable the development of novel targeted therapies. Prospective multicenter controlled trials are required to further refine management decisions and investigate the role of novel targeted therapies.

Potent Dual BET Bromodomain-Kinase Inhibitors as Value-Added Multitargeted Chemical Probes and Cancer Therapeutics

Synergistic action of kinase and BET bromodomain inhibitors in cell killing has been reported for a variety of cancers. Using the chemical scaffold of the JAK2 inhibitor TG101348, we developed and characterized single agents which potently and simultaneously inhibit BRD4 and a specific set of oncogenic tyrosine kinases including JAK2, FLT3, RET, and ROS1. Lead compounds showed on-target inhibition in several blood cancer cell lines and were highly efficacious at inhibiting the growth of hematopoietic progenitor cells from patients with myeloproliferative neoplasm. Screening across 931 cancer cell lines revealed differential growth inhibitory potential with highest activity against bone and blood cancers and greatly enhanced activity over the single BET inhibitor JQ1. Gene drug sensitivity analyses and drug combination studies indicate synergism of BRD4 and kinase inhibition as a plausible reason for the superior potency in cell killing. Combined, our findings indicate promising potential of these agents as novel chemical probes and cancer therapeutics. Mol Cancer Ther; 16(6); 1054-67. ©2017 AACR.

Chemotherapy Options for Poor Responders to Neoadjuvant Chemotherapy for Orbital Granulocytic Sarcoma

OPINION STATEMENT

Granulocytic sarcoma (GS) is a rare manifestation of myeloid proliferation, characterized by formation of a mass comprised of immature cells of myeloid origin. Orbital granulocytic sarcoma is rarer still, with only a small fraction of GS patients having orbital involvement. Given the rarity of orbital GS, no unified therapy plan has been identified, as large prospective trials are not feasible, but it is widely accepted that patients with GS ought to be treated with systemic intensive chemotherapy consistent with standard of care regimens for acute myelogenous leukemia (AML) or chronic myelogenous leukemia (CML). Development of a treatment plan for GS in poor responders involves a systemic leukemia plan as novel therapeutics have not been investigated for treatment GS per se, but used more widely for AML. GS is most commonly associated with AML and thus will be addressed in that context in this review. Patients with GS associated with CML should receive CML-specific therapy. When conventional and traditional cytotoxic GS/AML chemotherapy regimens are insufficient, patients often require a combination of novel therapeutics, stem cell transplantation (SCT), and radiation. Much of the recent advancement in AML therapy, as well as in AML translational research, has been in targeting molecular facets of the disease and enabling more specificity with treatment. The aim of treating patients for whom conventional treatment was unsuccessful with personalized therapy has not yet been realized, but many of the novel therapeutics reviewed below have demonstrated promise and are cause for optimism. In our center, when a GS/AML patient is refractory to frontline therapy, we rely on novel chemotherapy therapeutic options as outlined below.

Dihydroartemisinin and its derivative induce apoptosis in acute myeloid leukemia through Noxa-mediated pathway requiring iron and endoperoxide moiety

Anti-apoptotic protein Mcl-1 plays an important role in protecting cell from death in acute myeloid leukemia (AML). The apoptosis blocking activity of Mcl-1 is inhibited by BH3-only protein Noxa. We found that dihydroartemisinin (DHA) and its derivative X-11 are potent apoptosis inducers in AML cells and act through a Noxa-mediate pathway; X-11 is four-fold more active than DHA. DHA and X-11-induced apoptosis is associated with induction of Noxa; apoptosis is blocked by silencing Noxa. DHA and X-11 induce Noxa expression by upregulating the transcription factor FOXO3a in a reactive oxygen species-mediated pathway. Interfering with the integrity of the endoperoxide moiety of DHA and X-11, as well as chelating intracellular iron with deferoxamine, diminish apoptosis and Noxa induction. AML cells expressing Bcl-xL, or with overexpression of Bcl-2, have decreased sensitivity to DHA and X-11-induced apoptosis which could be overcome by addition of Bcl-2/Bcl-xL inhibitor ABT-737. DHA and X-11 represent a new group of AML cells-apoptosis inducing compounds which work through Noxa up-regulation utilizing the specific endoperoxide moiety and intracellular iron.

Higher expression levels of the HOXA9 gene, closely associated with MLL-PTD and EZH2 mutations, predict inferior outcome in acute myeloid leukemia

BACKGROUND

Although the biological insight of acute myeloid leukemia (AML) has increased in the past few years, the discovery of novel discriminative biomarkers remains of utmost value for improving outcome predictions. Systematical studies concerning the clinical implications and genetic correlations of HOXA9 aberrations in patients with AML are relatively promising.

MATERIALS AND METHODS

Here, we investigated mutational status and the mRNA levels of the HOXA9 gene in 258 patients with AML. Furthermore, hematological characteristics, chromosome abnormalities, and genetic mutations associated with AML were analyzed, followed by the assessment of clinical survival. Besides, the expression level and mutational status of MEIS1, a cofactor of HOXA9, were also detected in patients with AML with the aim of a deeper understanding about the homeodomain-containing transcription factors associated with hematological characteristics.

RESULTS

HOXA9 and MEIS1 mutations were detected in 4.26% and 3.49% AML cases, respectively. No correlations were detected between mutation status and clinical characteristics, cytogenetic and genetic aberrations, and clinical survival. Higher HOXA9 expression levels were correlated with white blood cell count and closely associated with unfavorable karyotype as well as MLL-PTD and EZH2 mutations, whereas, there was an inverse correlation with the French-American-British M3 subtype. Compared with patients with lower HOXA9 expression levels, those with higher HOXA9 expression levels had a lower complete remission rate and inferior survivals in both AML and cytogenetically normal AML.

CONCLUSION

HOXA9 expression may serve as a promising biomarker to ameliorate a prognostic model for predicting clinical outcome and consummating individualized treatment in patients with AML.

European cancer mortality predictions for the year 2016 with focus on leukaemias

BACKGROUND

Current cancer mortality statistics are important for public health decision-making and resource allocation. Age-standardized rates and numbers of deaths are predicted for 2016 in the European Union (EU).

PATIENTS AND METHODS

Population and death certification data for stomach, colorectum, pancreas, lung, breast, uterus, prostate, leukaemias and total cancers were obtained from the World Health Organization database and Eurostat. Figures were derived for the EU, France, Germany, Italy, Poland, Spain and the UK. Projected numbers of deaths by age group were obtained for 2016 by linear regression on estimated numbers of deaths over the most recent time period identified by a joinpoint regression model.

RESULTS

Projected total cancer mortality trends for 2016 in the EU are favourable in both sexes with rates of 133.5/100 000 men and 85.2/100 000 women (8% and 3% falls since 2011) corresponding to 753 600 and 605 900 deaths in men and women for a total number of 1 359 500 projected cancer deaths (+3% compared with 2011, due to population ageing). In men, lung, colorectal and prostate cancer have fallen 11%, 5% and 8%, respectively, since 2011. Breast and colorectal cancer trends in women are favourable (8% and 7% falls, respectively), but lung and pancreatic cancer rates have risen 5% and 4% since 2011 reaching rates of 14.4 and 5.6/100 000 women. Leukaemias show favourable projected mortality for both sexes and all age groups, with stronger falls in the younger age groups. All ages rates are 4.0/100 000 men and 2.5/100 000 women, with falls of 14% and 12% respectively.

CONCLUSION

The 2016 predictions for EU cancer mortality confirm the favourable trends in rates particularly for men. Lung cancer is likely to be the leading site for female cancer rates. Continuing falls in mortality, larger in children and young adults, are predicted in leukaemias, essentially due to advancements in management and therapy, and their subsequent adoption across Europe.

Extramedullary Manifestations of Myeloid Neoplasms

OBJECTIVES

This session of the 2013 Society of Hematopathology/European Association for Haematopathology workshop focused on extramedullary manifestations of myeloid neoplasms.

METHODS

We divided the submitted cases into four subgroups: (1) isolated myeloid sarcoma (MS); (2) MS with concurrent acute myeloid leukemia (AML), with a focus on karyotypic and molecular findings; (3) extramedullary relapse of AML, including relapse in the posttransplant setting; and (4) blast phase/transformation of a myeloproliferative neoplasm or chronic myelomonocytic leukemia.

RESULTS

Establishing a diagnosis of isolated MS requires a high index of suspicion and use of immunophenotypic methods. Recurrent cytogenetic abnormalities or gene mutations that occur in MS mirror those known to occur in AML.

CONCLUSIONS

In the era of targeted therapy and sophisticated risk stratification, every attempt must be made to perform a complete workup on MS cases (or concurrent AML) since the diagnosis of MS, in itself, is no longer adequate for patient management. Cases of blastic plasmacytoid dendritic cell neoplasm were also included and discussed in this session.

Oligonucleotide aptamer-drug conjugates for targeted therapy of acute myeloid leukemia

Oligonucleotide aptamers can specifically bind biomarkers on cancer cells and can be readily chemically modified with different functional molecules for personalized medicine. To target acute myeloid leukemia (AML) cells, we developed a single-strand DNA aptamer specific for the biomarker CD117, which is highly expressed on AML cells. Sequence alignment revealed that the aptamer contained a G-rich core region with a well-conserved functional G-quadruplex structure. Functional assays demonstrated that this synthetic aptamer was able to specifically precipitate CD117 proteins from cell lysates, selectively bound cultured and patient primary AML cells with high affinity (Kd < 5 nM), and was specifically internalized into CD117-expressing cells. For targeted AML treatment, aptamer-drug conjugates were fabricated by chemical synthesis of aptamer (Apt) with methotrexate (MTX), a central drug used in AML chemotherapy regimens. The formed Apt-MTX conjugates specifically inhibited AML cell growth, triggered cell apoptosis, and induced cell cycle arrest in G1 phase. Importantly, Apt-MTX had little effect on CD117-negative cells under the same treatment conditions. Moreover, exposure of patient marrow specimens to Apt-MTX resulted in selective growth inhibition of primary AML cells and had no toxicity to off-target background normal marrow cells within the same specimens. These findings indicate the potential clinical value of Apt-MTX for targeted AML therapy with minimal to no side effects in patients, and also open an avenue to chemical synthesis of new, targeted biotherapeutics.

The apoptotic mechanism of action of the sphingosine kinase 1 selective inhibitor SKI-178 in human acute myeloid leukemia cell lines

We previously developed SKI-178 (N'-[(1E)-1-(3,4-dimethoxyphenyl)ethylidene]-3-(4-methoxxyphenyl)-1H-pyrazole-5-carbohydrazide) as a novel sphingosine kinase-1 (SphK1) selective inhibitor and, herein, sought to determine the mechanism-of-action of SKI-178-induced cell death. Using human acute myeloid leukemia (AML) cell lines as a model, we present evidence that SKI-178 induces prolonged mitosis followed by apoptotic cell death through the intrinsic apoptotic cascade. Further examination of the mechanism of action of SKI-178 implicated c-Jun NH2-terminal kinase (JNK) and cyclin-dependent protein kinase 1 (CDK1) as critical factors required for SKI-178-induced apoptosis. In cell cycle synchronized human AML cell lines, we demonstrate that entry into mitosis is required for apoptotic induction by SKI-178 and that CDK1, not JNK, is required for SKI-178-induced apoptosis. We further demonstrate that the sustained activation of CDK1 during prolonged mitosis, mediated by SKI-178, leads to the simultaneous phosphorylation of the prosurvival Bcl-2 family members, Bcl-2 and Bcl-xl, as well as the phosphorylation and subsequent degradation of Mcl-1. Moreover, multidrug resistance mediated by multidrug-resistant protein1 and/or prosurvival Bcl-2 family member overexpression did not affect the sensitivity of AML cells to SKI-178. Taken together, these findings highlight the therapeutic potential of SKI-178 targeting SphK1 as a novel therapeutic agent for the treatment of AML, including multidrug-resistant/recurrent AML subtypes.

New agents for the treatment of lymphoid leukemia and lymphoma: focus on recent FDA approvals

Leukemia and lymphoma are systemic malignancies that represent half of all childhood cancers, though 90% occur in adults. Various treatment options are available, but therapy is mainly systemic chemotherapy plus appropriate monoclonal antibodies. In certain situations radiotherapy and bone marrow transplantation play a role. Some types/subtypes of these diseases are potentially curable, yet many leukemias and lymphomas do not properly respond to current therapies. Although the FDA (US Food and Drugs Administration) approvals of new drugs have shown a small increasing trend between 2007-2012, overall, the trend of new approvals remains relatively steady between 2006-2013, with a peak of 39 new drugs approved in 2012 and a drop in the new FDA drug approvals in 2013, to 27. Drugs approved for cancer treatment have shown a similar trend. Between 2006-2013, at least one drug was approved every year for the treatment of particular types of lymphoma or leukemia, except in 2010, with a peak of 5 new approvals in 2012. Between January 2013-March 2014, several important new approvals were made: ibrutinib for the treatment of CLL and mantle cell lymphoma (MCL), obinutuzumab for the treatment of CLL (in combination with chlorambucil), and lenalidomide for the treatment of mantle cell lymphoma. The results, importance, adverse effects and mechanisms of action of these agents are discussed in this review. These results held promise and their discovery and approval for the treatment of CLL and MCL is a major step forward. However, the emergence of resistance and the lack of cures need to be addressed by rational development of combination therapy, as well as development of novel drugs with enhanced potency or different mechanism of action, to achieve better overall and complete response rates with decreased toxicity.