GAS5 promotes cytarabine induced myelosuppression via inhibition of hematopoietic stem cell differentiation

Cytarabine (Ara-C) is widely used in the induction chemotherapy for acute myeloid leukemia (AML). Association between LncRNA GAS5 genetic polymorphism and the recovery of hematopoietic function after Ara-C-based chemotherapy is observed. This study aimed to identify whether intervention of GAS5 expression and GAS5 genotype affect Ara-C-induced inhibition of hematopoietic stem cells (HSCs) differentiation. In this study, cord blood-derived CD34+ cells were cultured in vitro, and a cell model of myelosuppression was established by treatment of CD34+ cells with Ara-C. The effect of GAS5 overexpression, Ara-C treatment, and GAS5 rs55829688 genotype on the hematopoietic colony-forming ability of CD34+ cells was assessed using methylcellulose-based colony forming unit assay. GAS5 overexpression slowed down the proliferation of cord blood-derived CD34+ cells significantly (p < 0.05) and decreased their ability to form hematopoietic colonies in vitro. Ara-C significantly reduced the hematopoietic colony-forming ability of CD34+ cells in vitro (p < 0.0001), and overexpressing GAS5 further decreased the number of hematopoietic colonies. GAS5 expression was higher in CD34+ cells than in CD34- cells, and positively correlated with GATA1 mRNA expression in CD34+ cells in vitro culture. However, GAS5 genotype had no effect on the total number of hematopoietic colonies formed from cord blood-derived CD34+ cells. In conclusion, our study highlights that GAS5 inhibited the in vitro proliferation and reduced the hematopoietic colony-forming ability of cord blood-derived CD34+ cells, with the most pronounced effect observed on CFU-GEMM formation. GAS5 also enhanced the inhibitory effect of Ara-C on the in vitro hematopoietic ability of CD34+ HSCs.

Phase I non-randomized clinical trial of allogeneic natural killer cells infusion in acute myeloid leukemia patients

INTRODUCTION

A new type of immune cell transplantation called allogeneic NK cell infusion is proposed as a potential universal off-the-shelf cell product for adoptive immune cell therapy in hematologic malignancies.

DESIGN

A multicentral phase I non-randomized clinical trial was conducted to assess the safety, feasibility, and potential efficacy of adoptively infused NK cells in patients with refractory/relapsed AML. We evaluated the feasibility of the trial by considering cell production, patient selection, and treatment protocol.

METHOD

Allogeneic NK cells were produced from random healthy unrelated donors; 10 patients were selected according to the inclusion criteria and were included in two groups in case of NK cell dose escalation. Two cell infusions were given, spaced 7 days apart, following a lymphodepletion conditioning regimen of fludarabin-endoxan administered 7 days before the first infusion. The intervention safety was scored using Common Terminology Criteria for Adverse Events (CTCAE) based on variations in vital signs due to cell infusion. NK cell chimerism, tumor burden, and duration of relapse were considered to be components of efficacy. The pilot feasibility evaluation was checked using the CONSORT platform.

RESULTS

The NK cell infusion procedure was well tolerated, and no grade 2-5 toxicities related (possible or probable) to PB-NK cell infusion were observed. Four patients developed grade 1 transient chills, headaches, vomiting, and bone pain following each PB-NK cell infusion that were not required hospitalization. One of these patients (p01) died because of severe acute respiratory syndrome. Of 9 evaluable patients, 6 (66.6%) showed stable disease (SD) and 3 (33.3%) presented progressive disease (PD). Of 6 SD patients, 2 (p08 and p09) remained alive in SD and 3 patients (p04, p05 and p07) converted to PD at 9 months after infusion of NK cells, and 1 (p03) was not evaluable due to follow-up loss. No patient achieved complete remission.

CONCLUSION

The study demonstrated the feasibility and safety of adoptive transfer of random healthy unrelated donor PB-NK cells in refractory/relapsed AML patients and supports continued study in phase II clinical trials in relapsed/refractory AML patients.

Is Treosulfan-Based Conditioning Attractive as a Reduced-Intensity Conditioning Regimen in Korea?

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) was not actively performed in elderly acute myeloid leukemia (AML) or myelodysplastic syndrome patients who are at a high-risk based on hematopoietic cell transplantation-specific comorbidity index (HCT-CI). The advent of reduced-intensity conditioning (RIC) regimens has made HSCT applicable in this population. However, the selection of appropriate conditioning is a major concern for the attending physician. The benefits of combination of treosulfan and fludarabine (Treo/Flu) have been confirmed through many clinical studies. Korean data on treosulfan-based conditioning regimen are scarce.

METHODS

A retrospective study was conducted to compare the clinical outcomes of allogeneic HSCT using RIC between 13 patients receiving Treo/Flu and 39 receiving busulfan/fludarabine (Bu/Flu).

RESULTS

In terms of conditioning-related complications, the frequency of ≥ grade 2 nausea or vomiting was significantly lower and the duration of symptoms was shorter in the Treo/Flu group than in the Bu/Flu group. The incidence of ≥ grade 2 mucositis tended to be lower in the Treo/Flu group. In the analysis of transplant outcomes, all events of acute graft versus host disease (GVHD) and ≥ grade 2 acute GVHD occurred more frequently in the Treo/Flu group. The frequency of Epstein-Barr virus reactivation was significantly higher in the Treo/Flu group (53.8% vs. 23.1%, P = 0.037). Non-relapse mortality (NRM) at 12 months was higher in the Treo/Flu group (30.8% vs. 7.7%, P = 0.035). Significant prognostic factors included disease type, especially secondary AML, disease status and high-risk based on HCT-CI, ≥ grade 2 acute GVHD, and cases requiring ≥ 2 immunosuppressive drugs for treating acute GVHD. In the comparison of survival outcomes according to conditioning regimen, the Bu/Flu group seemed to show better results than the Treo/Flu group (60% vs. 46.2%, P = 0.092 for overall survival; 56.4% vs. 38.5%, P = 0.193 for relapse-free survival). In additional analysis for only HCT-CI high-risk groups, there was no difference in transplant outcomes except that the Treo/Flu group tended to have a higher NRM within one year after transplantation. Survival outcomes of both groups were similar.

CONCLUSION

This study suggests that Treo/Flu conditioning may be an alternative to Bu/Flu regimen in elderly patients with high-risk who are not suitable for standard conditioning.

Esculetin releases maturation arrest and induces terminal differentiation in leukemic blast cells by altering the Wnt signaling axes

BACKGROUND

The "Differentiation therapy" has been emerging as a promising and more effective strategy against acute leukemia relapses.

OBJECTIVE

In extension to the revolutionising therapeutic outcomes of All Trans Retinoic Acid (ATRA) to induce terminal differentiation of Acute Promyelocytic Leukemic (APL) blast cells, we decipher the potential effect of a natural compound "Esculetin" to serve as a differentiating agent in Acute Myeloid Leukemia (AML). Underlaying role of Wnt signaling pathways in esculetin mediated blast cell differentiation was also evaluated.

METHODS

Human acute myeloid leukemic cells (Kasumi-1) with t(8;21/AML-ETO) translocation were used as a model system. Growth inhibitory and cytotoxic activity of esculetin were analysed using growth kinetics and MTT assay. Morphological alterations, cell scatter characteristics, NBT reduction assay and cell surface marker expression patterns were analysed to detect terminally differentiated phenotypes. We employed RT²profiler PCR array system for the analysis of transcriptome profile of Wnt signaling components. Calcium inhibitors (TMB8 and Amlodipine) and Transforming growth factor beta (TGF-β) were used to modulate the Wnt signaling axes.

RESULTS

We illustrate cytotoxic as well as blast cell differentiation potential of esculetin on Kasumi-1 cells. Morphological alterations akin to neutrophilic differentiation as well as the corresponding acquisition of myeloid lineage markers indicate terminal differentiation potential of esculetin in leukemic blast cells. Exposure to esculetin also resulted in downregulation of canonical Wnt axis while upto ~ 21 fold upregulation of non-canonical axis associated genes.

CONCLUSIONS

Our study highlights the importance of selective use of calcium pools as well as "axis shift" of the canonical to non-canonical Wnt signaling upon esculetin treatment which might abrogate the inherent proliferation to release maturation arrest and induce the differentiation in leukemic blast cells. The current findings provide further therapeutic interventions to consider esculetin as a potent differentiating agent to counteract AML relapses.

FAT1 Gene Expression in Iranian Acute Lymphoid and Myeloid Leukemia Patients

BACKGROUND

FAT atypical cadherin 1 (FAT1) is a member of the cadherin superfamily whose loss or gain is associated with the initiation and/or progression of different cancers. FAT1 overexpression has been reported in hematological malignancies. This research intended to investigate FAT1 gene expression in adult Iranian acute leukemia patients, compared to normal mobilized peripheral blood CD34+ cells.

MATERIALS AND METHODS

The peripheral blast (peripheral blood mononuclear cells) cells of 22 acute myeloid leukemia (AML), 14 acute lymphoid leukemia (ALL) patients, and mobilized peripheral blood CD34+ cells of 12 healthy volunteer stem cell donors were collected. Then, quantitative real-time polymerase chain reaction (qPCR) was used to compare FAT1 gene expression.

RESULTS

Overall, there were no significant differences in FAT1 expression between AML and ALL patients (p>0.2). Nonetheless, the mean expression level of FAT1 was significantly higher in leukemic patients (AML and ALL) than in normal CD34+ cells (p=0.029). Additionally, the FAT1 expression levels were significantly higher in both CD34+ and CD34- leukemic patients than in normal CD34+ cells (p=0.028).

CONCLUSION

No significant differences were found between FAT1 expression in CD34+ and CD34- leukemic samples (p> 0.3). Thus, higher FAT1 expression was evident in ALL and AML leukemia cells but this appeared unrelated to CD34 expression. This suggests in a proportion of adult acute leukemia, FAT1 expression may prove to be a suitable target for therapeutic strategies.

SFXN3 is Associated with Poor Clinical Outcomes and Sensitivity to the Hypomethylating Therapy in Non-M3 Acute Myeloid Leukemia Patients

BACKGROUND

DNA hypermethylation plays a critical role in the occurrence and progression of acute myeloid leukemia (AML). The mitochondrial serine transporter, SFXN3, is vital for onecarbon metabolism and DNA methylation. However, the impact of SFXN3 on the occurrence and progression of AML has not been reported yet.

OBJECTIVE

In this study, we hypothesized that SFXN3 indicates a poor prognosis and suggested tailored treatment for AML patients.

METHODS

We used GEPIA and TCGA repository data to analyze the expression of SFXN3 and its correlation with survival in AML patients. RT-qPCR was used to detect the SFXN3 level in our enrolled AML patients and volunteers. Additionally, Whole Genome Bisulfite Sequencing (WGBS) was used to detect the genomic methylation level in individuals.

RESULTS

Through the TCGA and GEPIA databases, we found that SFXN3 was enriched in AML patients, predicting shorter survival. Furthermore, we confirmed that SFXN3 was primarily overexpressed in AML patients, especially non-M3 patients, and that high SFXN3 in non-M3 AML patients was found to be associated with poor outcomes and frequent blast cells. Interestingly, non-M3 AML patients with high SFXN3 levels who received hypomethylating therapy showed a higher CR ratio. Finally, we found that SFXN3 could promote DNA methylation at transcription start sites (TSS) in non-M3 AML patients. These sites were found to be clustered in multiple vital cell functions and frequently accompanied by mutations in DNMT3A and NPM1.

CONCLUSION

In conclusion, SXFN3 plays an important role in the progression and hypermethylation in non-M3 AML patients and could be a potential biomarker for indicating a high CR rate for hypomethylating therapy.

Distinct power of bone marrow microRNA signatures and tumor suppressor genes for early detection of acute leukemia

BACKGROUND

Acute leukemia involving lymphocytic and myeloid cells is cancer with a high mortality rate. Swift and timely diagnosis might be a potential approach to improving patient prognosis and survival. The microRNA (miRNA) signatures are emerging nowadays for their promising diagnostic potential. MiRNA levels from bone marrow can be used as prognostic biomarkers.

METHODS

The current study was designed to evaluate if the microRNAs and tumor suppressor genes (TSGs) profiling of hematopoietic bone marrow could help in acute leukemia early detection. Also, we assessed the DNA methyltransferase 3A (DNMT3A) expression and its possible epigenetic effects on miRNAs plus TSGs expression levels. The expression levels of ten miRNAs and four TSGs involved in acute lymphocytic leukemia (ALL) as well as acute myeloid leukemia (AML) were quantified in 43 and 40 bone marrow samples of ALL and AML patients in comparison with cancer-free subjects via real-time quantitative PCR (RT-qPCR). The receiver-operating-characteristic (ROC) analysis of miRNAs was performed in the study groups. Further, the correlation between the DNMT3A and TSGs was calculated.

RESULTS

Significant differences were detected in the bone marrow expression of miRNAs and TSGs (P < 0.05) between acute leukemia patients and healthy group. ROC analysis confirmed the ability of miR-30a, miR-101, miR-132, miR-129, miR-124, and miR-143 to discriminate both ALL and AML patients with an area under the ROC curve of ≥ 0.80 (P < 0.001) and high accuracy. The correlation between DNMT3A and P15/P16 TSGs revealed that DNMT3A plays a vital role in epigenetic control of TSGs expression. Our findings indicated that the downregulation of bone marrow miRNAs and TSGs was accompanied by acute leukemia development.

CONCLUSIONS

The authors conclude that this study could contribute to introducing useful biomarkers for acute leukemia diagnosis.

Expression and prognostic significance of chromatin modulators EHMT2/G9a and KDM2b in acute myeloid leukemia

Epigenetics factors are critical for normal cell function and their regulation is sensitive to malignancy development. EHMT2/G9a and KDM2b are key epigenetics players in different cancer types. However, their expression profiles and related consequences in acute myeloid leukemia (AML) patients have not been known yet. In addition to routine lab work, expression levels of EHMT2/G9a and KDM2b were determined in 110 adult and pediatric patients with De Novo AML. Relations between their expression and patients' clinical data were tested by statistical methods. EHMT2/G9a and KDM2b were highly expressed in AML patients against control cases and associated with the presence of adverse genomic alterations. In response to induction chemotherapy, EHMT2/G9a and KDM2b showed to be significantly high in resistant and relapsed patients in comparison to the complete remission group. KDM2b overexpression was associated with CD11c (integrin alpha X) downregulation. Kaplan-Meier analysis indicated that EHMT2/G9a and KDM2b overexpression was correlated with poor survival status in AML patients. We conclude that EHMT2/G9a and KDM2b expression levels could be used as independent prognostic factors for AML disease.

Genome-scale integration of transcriptome and metabolome unveils squalene synthase and dihydrofolate reductase as targets against AML cells resistant to chemotherapy

The development of resistance to chemotherapeutic agents, such as Doxorubicin (DOX) and cytarabine (AraC), is one of the greatest challenges to the successful treatment of Acute Myeloid Leukemia (AML). Such acquisition is often underlined by a metabolic reprogramming that can provide a therapeutic opportunity, as it can lead to the emergence of vulnerabilities and dependencies to be exploited as targets against the resistant cells. In this regard, genome-scale metabolic models (GSMMs) have emerged as powerful tools to integrate multiple layers of data to build cancer-specific models and identify putative metabolic vulnerabilities. Here, we use genome-scale metabolic modelling to reconstruct a GSMM of the THP1 AML cell line and two derivative cell lines, one with acquired resistance to AraC and the second with acquired resistance to DOX. We also explore how, adding to the transcriptomic layer, the metabolomic layer enhances the selectivity of the resulting condition specific reconstructions. The resulting models enabled us to identify and experimentally validate that drug-resistant THP1 cells are sensitive to the FDA-approved antifolate methotrexate. Moreover, we discovered and validated that the resistant cell lines could be selectively targeted by inhibiting squalene synthase, providing a new and promising strategy to directly inhibit cholesterol synthesis in AML drug resistant cells.

Expression of RUNX1-ETO Rapidly Alters the Chromatin Landscape and Growth of Early Human Myeloid Precursor Cells

Acute myeloid leukemia (AML) is a hematopoietic malignancy caused by recurrent mutations in genes encoding transcriptional, chromatin, and/or signaling regulators. The t(8;21) translocation generates the aberrant transcription factor RUNX1-ETO (RUNX1-RUNX1T1), which by itself is insufficient to cause disease. t(8;21) AML patients show extensive chromatin reprogramming and have acquired additional mutations. Therefore, the genomic and developmental effects directly and solely attributable to RUNX1-ETO expression are unclear. To address this, we employ a human embryonic stem cell differentiation system capable of forming definitive myeloid progenitor cells to express RUNX1-ETO in an inducible fashion. Induction of RUNX1-ETO causes extensive chromatin reprogramming by interfering with RUNX1 binding, blocks differentiation, and arrests cellular growth, whereby growth arrest is reversible following RUNX1-ETO removal. Single-cell gene expression analyses show that RUNX1-ETO induction alters the differentiation of early myeloid progenitors, but not of other progenitor types, indicating that oncoprotein-mediated transcriptional reprogramming is highly target cell specific.

•

RUNX1-ETO reversibly arrests the growth of human ESC-derived early myeloid cells

•

RUNX1-ETO disrupts global RUNX1 binding and deregulates RUNX1 target genes

•

RUNX1-ETO blocks myeloid differentiation by rapidly downregulating SPI1 and CEBPA

•

The impact of RUNX1-ETO induction is cell type specific

Precision medicine in myeloid malignancies

Myeloid malignancies have always been at the forefront of an improved understanding of the molecular pathogenesis of cancer. In accordance, over the last years, basic research focusing on the aberrations underlying malignant transformation of myeloid cells has provided the basis for precision medicine approaches and subsequently has led to the development of powerful therapeutic strategies. In this review article, we will recapitulate what has happened since in the 1980s the use of all-trans retinoic acid (ATRA), as a first targeted cancer therapy, has changed one of the deadliest leukemia subtypes, acute promyelocytic leukemia (APL), into one that can be cured without classical chemotherapy today. Similarly, imatinib, the first molecularly designed cancer therapy, has revolutionized the management of chronic myeloid leukemia (CML). Thus, targeted treatment approaches have become the paradigm for myeloid malignancy, but many questions still remain unanswered, especially how identical mutations can be associated with different phenotypes. This might be linked to the impact of the cell of origin, gene-gene interactions, or the tumor microenvironment including the immune system. Continuous research in the field of myeloid neoplasia has started to unravel the molecular pathways that are not only crucial for initial treatment response, but also resistance of leukemia cells under therapy. Ongoing studies focusing on leukemia cell vulnerabilities do already point to novel (targetable) "Achilles heels" that can further improve myeloid cancer therapy.

A three-gene signature might predict prognosis in patients with acute myeloid leukemia

The identification of effective signatures is crucial to predict the prognosis of acute myeloid leukemia (AML). The investigation aimed to identify a new signature for AML prognostic prediction by using the three-gene expression (octamer-binding transcription factor 4 (OCT4), POU domain type 5 transcription factor 1B (POU5F1B) and B-cell-specific Moloney murine leukemia virus integration site-1 pseudogene 1 (BMI1P1). The expressions of genes were obtained from our previous study. Only the specimens in which three genes were all expressed were included in this research. A three-gene signature was constructed by the multivariate Cox regression analyses to divide patients into high-risk and low-risk groups. Receiver operating characteristic (ROC) analysis of the three-gene signature (area under ROC curve (AUC) = 0.901, 95% CI: 0.821–0.981, P<0.001) indicated that it was a more valuable signature for distinguishing between patients and controls than any of the three genes. Moreover, white blood cells (WBCs, P=0.004), platelets (PLTs, P=0.017), percentage of blasts in bone marrow (BM) (P=0.011) and complete remission (CR, P=0.027) had significant differences between two groups. Furthermore, high-risk group had shorter leukemia-free survival (LFS) and overall survival (OS) than low-risk group (P=0.026; P=0.006), and the three-gene signature was a prognostic factor. Our three-gene signature for prognosis prediction in AML may serve as a prognostic biomarker.

Bioactive Compounds from Seaweed with Anti-Leukemic Activity: A Mini-Review on Carotenoids and Phlorotannins

Chronic Myeloid Leukemia (CML) represents 15-20% of all new cases of leukemia and is characterized by an uncontrolled proliferation of abnormal myeloid cells. Currently, the first-line of treatment involves Tyrosine Kinase Inhibitors (TKIs), which specifically inhibits the activity of the fusion protein BCR-ABL. However, resistance, mainly due to mutations, can occur. In the attempt to find more effective and less toxic therapies, several approaches are taken into consideration such as research of new anti-leukemic drugs and "combination chemotherapy" where different drugs that act by different mechanisms are used. Here, we reviewed the molecular mechanisms of CML, the main mechanisms of drug resistance and current strategies to enhance the therapeutic effect of TKIs in CML. Despite major advances in CML treatment, new, more potent anticancer drugs and with fewer side effects are needed. Marine organisms, and particularly seaweed, have a high diversity of bioactive compounds with some of them having anticancer activity in several in vitro and in vivo models. The state-of-art suggests that their use during cancer treatment may improve the outcome. We reviewed here the yet few data supporting anti-leukemic activity of some carotenoids and phlorotannins in some leukemia models. Also, strategies to overcome drug resistance are discussed, particularly the combination of conventional drugs with natural compounds.

Inhibition of mTORC1/P70S6K pathway by Metformin synergistically sensitizes Acute Myeloid Leukemia to Ara-C

AIMS

Chemo-resistance still was the main obstacle for AML patients, more effective and less toxic forms of therapies were desperately needed. Metformin, a classic hypoglycemic drug for diabetes recently delivered us a new identity that it exerted anti-tumor activity through suppressing mTOR in various tumors. But the anti-tumor effect of metformin in AML was not clear.

METHODS

In this study, we used CCK8 assay and apoptosis assay to determine the anti-leukemia activity of metformin combined with AraC, and explore the mechanism of the joint role of Ara-C/metformin in AML. We finally used xenograft experiment in mice to determine the anti-leukemia effect of Ara-C/metformin in vivo.

KEY FINDINGS

We found that metformin could synergistically sensitize AML cells to Ara-C via inhibiting mTORC1/P70S6K pathway. In vivo experiment also verified metformin in aid of Ara-C caused an obviously synergistic anti-tumor effect.

SIGNIFICANCE

We firstly found the synergistic anti-tumor effect of Ara-C/metformin in AML through inhibiting mTORC1/P70S6K pathway.

The prognostic significance of the long non-coding RNAs "CCAT1, PVT1" in t(8;21) associated Acute Myeloid Leukemia

Long non-coding RNA (LncRNA) is recently linked to various types of cancers, CCAT and PVT1 are two LncRNAs linked to t(8;21) associated Acute Myeloid Leukemia, the interplay between CCAT, PVT1 and the MYC proto-oncogene implicated in t(8;21) could present an opportunity for using LncRNA as prognostic biomarker or a target for therapy, We investigated the expression levels of LncRNAs in 70 patients; 30 with t(8;21) positive AML and 40 with t(8;21) negative AML, We found that CCAT1 and PVT1 are expressed in higher levels in t(8;21) positive -AML by 5.3 folds compared to t(8;21) negative group; the expression values were significantly associated with high-risk clinical criteria; moreover, they are associated with lower overall survival (OS) rate and leukemia-free survival (LFS), however we didn't find a statistically significant cut-off value of LncRNAs using the Cox regression analysis for Lnc_PVT1 except with LFS, we conclude that high expression levels of CCAT1 and PVT1 are associated with poor prognosis while being poor prognostic biomarkers in t(8;21) associated AML.

Characterization of TRKA signaling in acute myeloid leukemia

Tropomyosin-related kinase A (TRKA) translocations have oncogenic potential and have been found in rare cases of solid tumors. Accumulating evidence indicates that TRKA and its ligand, nerve growth factor (NGF), may play a role in normal hematopoiesis and may be deregulated in leukemogenesis. Here, we report a comprehensive evaluation of TRKA signaling in normal and leukemic cells. TRKA expression is highest in common myeloid progenitors and is overexpressed in core binding factor and megakaryocytic leukemias, especially Down syndrome-related AML. Importantly, NGF can rescue GM-CSF dependent TF-1 AML cells, but does not drive proliferation in other TRKA-expressing lines. Although TRKA expression is heterogeneous between and within AML samples, NGF stimulation broadly induces ERK signaling, demonstrating the functional ability of AML cells to respond to NGF/TRKA signaling. However, neither shRNA knockdown nor pharmacologic inhibition have significant anti-proliferative effects on human AML cells in vitro and in vivo. Thus, despite functional NGF/TRKA signaling, the importance of TRKA in AML remains unclear.

Asparaginase Erwinia chrysanthemi effectively depletes plasma glutamine in adult patients with relapsed/refractory acute myeloid leukemia

Depletion of glutamine (Gln) has emerged as a potential therapeutic approach in the treatment of acute myeloid leukemia (AML), as neoplastic cells require Gln for synthesis of cellular components essential for survival. Asparaginases deplete Gln, and asparaginase derived from Erwinia chrysanthemi (Erwinaze) appears to have the greatest glutaminase activity of the available asparaginases. In this Phase I study, we sought to determine the dose of Erwinaze that safely and effectively depletes plasma Gln levels to ≤ 120 μmol/L in patients with relapsed or refractory (R/R) AML. Five patients were enrolled before the study was halted due to issues with Erwinaze manufacturing supply. All patients received Erwinaze at a dose of 25,000 IU/m² intravenously three times weekly for 2 weeks. Median trough plasma Gln level at 48 h after initial Erwinaze administration was 27.6 μmol/L, and 80% (lower limit of 1-sided 95% CI 34%) of patients achieved at least one undetectable plasma Gln value (< 12.5 μmol/L), with the fold reduction (FR) in Gln level at 3 days, relative to baseline, being 0.16 (p < 0.001 for rejecting FR = 1). No dose-limiting toxicities were identified. Two patients responded, one achieved partial remission and one achieved hematologic improvement after six doses of Erwinaze monotherapy. These data suggest asparaginase-induced Gln depletion may have an important role in the management of patients with AML, and support more pharmacologic and clinical studies on the mechanistically designed asparaginase combinations in AML.

Autophagy limits proliferation and glycolytic metabolism in acute myeloid leukemia. Cell Death Discov. 2015;1. [PMID: 26568842 PMCID: PMC4641322 DOI: 10.1038/cddiscovery.2015.8]

Decreased autophagy contributes to malignancies, however it is unclear how autophagy impacts on tumour growth. Acute myeloid leukemia (AML) is an ideal model to address this as (i) patient samples are easily accessible, (ii) the hematopoietic stem and progenitor population (HSPC) where transformation occurs is well characterized, and (iii) loss of the key autophagy gene Atg7 in hematopoietic stem and progenitor cells (HSPCs) leads to a lethal pre-leukemic phenotype in mice. Here we demonstrate that loss of Atg5 results in an identical HSPC phenotype as loss of Atg7, confirming a general role for autophagy in HSPC regulation. Compared to more committed/mature hematopoietic cells, healthy human and mouse HSCs displayed enhanced basal autophagic flux, limiting mitochondrial damage and reactive oxygen species in this long-lived population. Taken together, with our previous findings these data are compatible with autophagy limiting leukemic transformation. In line with this, autophagy gene losses are found within chromosomal regions that are commonly deleted in human AML. Moreover, human AML blasts showed reduced expression of autophagy genes, and displayed decreased autophagic flux with accumulation of unhealthy mitochondria indicating that deficient autophagy may be beneficial to human AML. Crucially, heterozygous loss of autophagy in an MLL-ENL model of AML led to increased proliferation in vitro, a glycolytic shift, and more aggressive leukemias in vivo. With autophagy gene losses also identified in multiple other malignancies, these findings point to low autophagy providing a general advantage for tumour growth.

XPD DNA nucleotide excision repair gene polymorphisms associated with DNA repair deficiency predict better treatment outcomes in secondary acute myeloid leukemia

Pharmacogenetic studies in DNA repair pathway have consistently demonstrated correlations between the XRCC1 Arg399Gln, XPD Lys751Gln and XPD Asp312Gln genotypes, previously associated with suboptimal DNA repair, and differential cancer treatment outcomes. We evaluated these polymorphisms and XPD haplotypes in adult de novo (n=214) and secondary (n=79) acute myeloid leukemia (AML) patients treated with cytarabine and anthracycline chemotherapy. Genotyping was performed by MALDI-TOF mass spectrometry. Logistic and proportional hazards regression models were used to evaluate relationships. Differential responses were observed in secondary, but not de novo, AML. Among secondary AML patients, the odds of achieving complete remission (CR) were higher for the XPD 312Asn/Asn (OR= 11.23; 95% CI, 2.23-56.63) and XPD 751Gln/Gln (OR= 7.07; 95% CI, 1.42-35.18) genotypes. The XPD diplotypes were coded as the combination of two of the following haplotypes: haplotype A=(Lys)751A/(Asp) 312G; B=(Gln)751C/(Asn)312A; C=(Lys)751A/(Asn)312A; and D=(Gln)751C/(Asp)312G. The BB diplotype was associated with CR attainment [OR=18.31; 95% CI: 2.08-283.57] and longer survival [HR=0.31; 95% CI: 0.14-0.73] compared to the referent AA diplotype. The XPD 751 CC, 312GA, 312AA genotypes and the XPD DC diplotype were also associated with longer overall survival (OS).Thus, XPD codon 312 and 751 variant genotypes and haplotypes containing at least one variant allele may predict better treatment responses. If validated, these findings could support stratification of chemotherapy in secondary AML.