Purpose of review
We summarize recent advances for acute myeloid leukemia (AML) in older patients, with a focus on immunotherapeutics. Although the recently updated US SEER data still show that the majority of older AML patients do not receive any therapy, this reality is slowly changing. Advances in our understanding of the biology of AML and in the field of immunology are facilitating the development of alternative therapeutic options for patients, affording more and novel opportunities for potentially curative treatment.
Data from multiple cooperative groups show that older patients benefit from the incorporation of gemtuzumab ozogamicin, an anti-CD33 mAb toxin, into induction regimens. The first prospective study for Reduced-intensity conditioning (RIC) Allogeneic Hematopoietic Stem Cell Transplantation in older AML patients was reported at ASH 2012; the approach was feasible and improved Disease-Free Survival over conventional chemotherapy. Proof-of-concept trials targeting specific antigens such as WT1 or novel unique leukemia-associated antigens are currently underway, as well as other trials using chimeric antigen receptor T cells or (Natural Killer NK/effector cells in nontransplantation settings.
Wider application of immunotherapies such as allogeneic hematopoietic stem cell transplantation with RIC have altered the landscape and offer potential for cure of an increasing number of older AML patients.
immunotherapy; natural killer cells; older acute myeloid leukemia patients
We previously reported that bortezomib indirectly modulates transcription of DNA methyltransferase 1 (DNMT). We designed a phase I study of azacitidine (a direct DNMT inhibitor) plus bortezomib in acute myeloid leukemia (AML) to determine safety and tolerability. Twenty-three adults with relapsed/refractory AML received azacitidine 75mg/m2 daily on days 1-7. Bortezomib was dose escalated from 0.7mg/m2 on days 2 and 5 to 1.3mg/m2 on days 2, 5, 9, and 12. The target dose was reached without dose limiting toxicities. Infection and/or febrile neutropenia were frequent. Patients received a median of 2 cycles of therapy (range, 1-12+). Five of 23 patients achieved remission including two with morphologic and cytogenetic complete response (CR) and three with CR and incomplete count recovery (CRi). Of CR/CRi responders with cytogenetic abnormalities at baseline, three of four achieved cytogenetic CR. The combination of azacitidine and bortezomib was tolerable and active in this cohort of poor-risk previously-treated AML patients.
Relapsed AML; bortezomib; velcade
miR-29b directly or indirectly targets genes involved in acute myeloid leukemia (AML) i.e., DNMTs, CDK6, SP1, KIT and FLT3. Higher miR-29b pretreatment expression is associated with improved response to decitabine and better outcome in AML. Thus designing a strategy to increase miR-29b levels in AML blasts may be of therapeutic value. However, free synthetic miRs are easily degraded in bio-fluids and have limited cellular uptake. To overcome these limitations, we developed a novel transferrin-conjugated nanoparticle delivery system for synthetic miR-29b (Tf-NP-miR-29b).
Delivery efficiency was investigated by flow-cytometry, confocal microscopy and quantitative-PCR. The expression of miR-29b targets was measured by immunoblotting. The anti-leukemic activity of Tf-NP-miR-29b was evaluated by measuring cell proliferation and colony formation ability and in a leukemia mouse model.
Tf-NP-miR-29b treatment resulted in >200-fold increase of mature miR-29b compared to free miR-29b and was about twice as efficient as treatment with non-Tf-conjugated NP-miR-29b. Tf-NP-miR-29b treatment significantly downregulated DNMTs, CDK6, SP1, KIT and FLT3 and decreased AML cell growth by 30–50% and impaired colony formation by approximately 50%. Mice engrafted with AML cells and then treated with Tf-NP-miR-29b had significantly longer survival compared to Tf-NP-scramble (P=0.015) or free miR-29b (P=0.003). Furthermore, priming AML cell with Tf-NP-miR-29b before decitabine resulted in strong cell viability decrease in vitro and showed improved anti-leukemic activity compared with decitabine alone (P=0.001) in vivo.
Tf-NP effectively delivered functional miR-29b, resulting in target downregulation and anti-leukemic activity, and warrants further investigation as a novel therapeutic approach in AML.
lipopolyplex nanoparticles; miR-29b; Acute Myeloid Leukemia
We sought to reduce the risk of infectious complications and non-relapse mortality (NRM) associated with the use of antithymocyte globulin (ATG) without compromising control of acute graft-versus-host disease (GVHD) in patients undergoing reduced intensity conditioning (RIC) transplantation.
As part of an ongoing quality improvement effort, we lowered the dose of rabbit ATG from 7.5 mg/kg of ATG (R-ATG) (n=39) to 6.0 mg/kg of ATG (r-ATG) (n=33) in association with fludarabine and busulfan RIC transplantation and then monitored patients for adverse events, relapse, and survival.
Of the 72 mostly high risk (82%) patients studied, 89% received unrelated donor allografts, 25% of which were HLA-mismatched. No differences in post-transplantation full donor-cell chimerism rates were observed between the two ATG-dose groups (p>0.05). When R-ATG vs. r-ATG patients were compared, we observed no significant difference in the cumulative incidence of grade II–IV acute GVHD (32% vs. 27%; p-=0.73) or grade III–IV acute GVHD (23% vs. 11%; p=0.28). However, the r-ATG group had significantly less CMV reactivation (64% vs. 30%; p=0.005) and bacterial infections (56% vs. 18%; p=0.001), a better 1-year cumulative incidence of NRM (18% vs. 3%; p=0.03) and a trend for better 1-year overall survival (64% vs. 84%; p=0.07) compared to R-ATG patients.
A seemingly modest reduction in the dose of rabbit ATG did not compromise control of acute GVHD or achievement of donor chimerism but led to a significant decrease in the risk of serious infections and NRM in high risk RIC allograft recipients.
Fludarabine; busulfan; thymoglobulin; antithymocyte globulin; allogeneic stem cell transplantation; graft-versus-host disease
Aberrant expression of the secreted protein, acidic, cysteine-rich (osteonectin) (SPARC) gene, which encodes a matricellular protein that participates in normal tissue remodeling, is associated with a variety of diseases including cancer, but the contribution of SPARC to malignant growth remains controversial. We previously reported that SPARC was among the most upregulated genes in cytogenetically normal acute myeloid leukemia (CN-AML) patients with gene-expression profiles predictive of unfavorable outcome, such as mutations in isocitrate dehydrogenase 2 (IDH2-R172) and overexpression of the oncogenes brain and acute leukemia, cytoplasmic (BAALC) and v-ets erythroblastosis virus E26 oncogene homolog (ERG). In contrast, SPARC was downregulated in CN-AML patients harboring mutations in nucleophosmin (NPM1) that are associated with favorable prognosis. Based on these observations, we hypothesized that SPARC expression is clinically relevant in AML. Here, we found that SPARC overexpression is associated with adverse outcome in CN-AML patients and promotes aggressive leukemia growth in murine models of AML. In leukemia cells, SPARC expression was mediated by the SP1/NF-κB transactivation complex. Furthermore, secreted SPARC activated the integrin-linked kinase/AKT (ILK/AKT) pathway, likely via integrin interaction, and subsequent β-catenin signaling, which is involved in leukemia cell self-renewal. Pharmacologic inhibition of the SP1/NF-κB complex resulted in SPARC downregulation and leukemia growth inhibition. Together, our data indicate that evaluation of SPARC expression has prognosticative value and SPARC is a potential therapeutic target for AML.
The purpose of this study was to determine remission induction frequency when bortezomib was combined with daunorubicin and cytarabine in previously untreated older adults with acute myeloid leukemia (AML) and safety of bortezomib in combination with consolidation chemotherapy consisting of intermediate-dose cytarabine (Int-DAC).
Patients and Methods
Ninety-five adults (age 60 to 75 years; median, 67 years) with previously untreated AML (including therapy-related and previous myelodysplastic syndrome) received bortezomib 1.3 mg/m2 intravenously (IV) on days 1, 4, 8, and 11 with daunorubicin 60 mg/m2 on days 1 through 3 and cytarabine 100 mg/m2 by continuous IV infusion on days 1 through 7. Patients who achieved complete remission (CR) received up to two courses of consolidation chemotherapy with cytarabine 2 gm/m2 on days 1 through 5 with bortezomib. Three cohorts with escalating dose levels of bortezomib were tested (0.7, 1.0, and 1.3 mg/m2). Dose-limiting toxicities were assessed during the first cycle of consolidation. The relationship between cell surface expression of CD74 and clinical outcome was assessed.
Frequency of CR was 65% (62 of 95), and 4% of patients (four of 95) achieved CR with incomplete platelet recovery (CRp). Eleven patients developed grade 3 sensory neuropathy. Bortezomib plus Int-DAC proved tolerable at the highest dose tested. Lower CD74 expression was associated with CR/CRp (P = .04) but not with disease-free or overall survival.
The addition of bortezomib to standard 3 + 7 daunorubicin and cytarabine induction chemotherapy for AML resulted in an encouraging remission rate. The maximum tested dose of bortezomib administered in combination with Int-DAC for remission consolidation was 1.3 mg/m2 and proved tolerable. Further testing of this regimen is planned.
This phase I study was conducted to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT) of the heat shock protein 90 (HSP90) inhibitor 17-allyamino-17-demethoxygeldanamycin (17-AAG) in combination with bortezomib, and to provide pharmacokinetic data in relapsed or refractory acute myeloid leukemia (AML). Eleven patients were enrolled. The MTD was 17-AAG 150mg/m2 and bortezomib 0.7mg/m2. Hepatic toxicity and cardiac toxicity were dose limiting. Co-administration on day 4 led to a decrease in clearance (p=0.005) and increase in AUC (p=.032) of 17-amino-17-demethoxygeldanamycin (17-AG) not observed when 17-AAG was administered alone. Pharmacokinetic parameters of patients who developed toxicities and those who did not were not different. The combination of 17-AAG and bortezomib led to toxicity without measurable response in patients with relapsed or refractory AML. Pharmacokinetic data provide insight for studies of related agents in AML; next generation HSP90 inhibitors are appealing for further development in this area.
Relapsed AML; bortezomib; 17-AAG; heat shock protein inhibition
Decitabine (DAC) is used for treatment of patients with myelodysplastic syndromes and acute myeloid leukemia (AML). Following cellular uptake, DAC is activated to DAC-triphosphate (TP) and incorporated into DNA. Once incorporated into the DNA, DAC-TP binds and inactivates DNA methyltransferases (DNMTs), thereby leading to hypomethylation and re-expression of epigenetically silenced tumor suppressor genes and ultimately antileukemia activity. However, direct evidence of in vivo DAC-TP occurrence in DAC-treated patients has been difficult to demonstrate due to a lack of suitable validated analytical methodology. Thus, we developed and validated a nonradioactive sensitive and specific LC-MS/MS assay for quantification of DAC-TP. The assay is linear from 50 to 1,000 nM and from 1 to 10 μM and has a lower limit of quantitation of 50 nM and a coefficient of variation for both within- and between-day precision <20%. Following DAC treatment, we detected DAC-TP in parental and DAC-resistant AML cells (in vitro) and bone marrow (BM) and spleen of normal and leukemic mice (in vivo). Downregulation of DNMTs and correlation of DAC-TP concentration with proteins involved in mechanisms of DAC resistance were also demonstrated. The clinical applicability of this method was proven by measuring DAC-TP level in BM and blood mononuclear cells from DAC-treated AML patients. Higher levels are seemingly associated with clinical response. Monitoring the DAC-TP intracellular level may serve as a novel pharmacological endpoint for designing more effective DAC-based regimens.
acute myeloid leukemia; decitabine; metabolite; quantification method; triphosphate
A sensitive method was developed and validated for the measurement of 17-(allylamino)-17-demethoxygeldanamycin (17AAG) and its active metabolite 17-amino-17-demethoxygeldanamycin (17AG) in human plasma using 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17DMAG) as an internal standard. After the addition of internal standard, 200 µL of plasma was extracted using ice cold acetonitrile followed by analysis on a Thermo Finnigan triple-quadruple mass spectrometer coupled to an Agilent 1100 HPLC system. Chromatography was carried out on a 50 × 2.1 mm Agilent Zorbax SB-phenyl 5 µm column coupled to a 3mm Varian metaguard diphenyl pre-column using glacial acetic acid 0.1% and a gradient of acetonitrile and water at a flow rate of 500 µL/min. Atmospheric pressure chemical ionization and detection of 17AAG, 17AG and 17DMAG were accomplished using selected reaction monitoring of m/z 584.3 > 541.3, 544.2 > 501.2, and 615.3 >572.3 respectively in negative ion mode. Retention times for 17AAG, 17AG, and 17DMAG were 4.1, 3.5, and 2.9 minutes, respectively, with a total run time of 7 minutes. The assay was linear over the range 0.5–3000 ng/mL for 17AAG and 17AG. Replicate sample analysis indicated within- and between-run accuracy and precision within 15%. The recovery of 17AAG and 17AG from 200 µL of plasma containing 1, 25, 300, and 2500 ng/mL was 93% or greater. This high performance liquid chromatographic tandem mass spectroscopy (HPLC/MS/MS) method is superior to previous methods. It is the first analytical method reported to date for the quantitation of both 17AAG and its metabolite 17AG and can reliably quantitate concentrations of both compounds as low as 0.5 ng/mL.
Histone deacetylase (HDAC) inhibitors either alone or in combination with hypomethylating agents have limited clinical effect in acute myeloid leukemia (AML). Previously we demonstrated that AML patients with higher miR-29b expression had better response to the hypomethylating agent decitabine. Therefore, an increase in miR-29b expression preceding decitabine treatment may provide a therapeutic advantage. We previously showed that miR-29b expression is suppressed by a repressor complex that includes HDACs. Thus, HDAC inhibition may increase miR-29b expression. We hypothesized that priming AML cells with the novel HDAC inhibitor (HDACI) AR-42 would result in increased response to decitabine treatment via upregulation of miR-29b. Here we show that AR-42 is a potent HDACI in AML, increasing miR-29b levels and leading to downregulation of known miR-29b targets (i.e., SP1, DNMT1, DNMT3A, and DNMT3B). We then demonstrated that the sequential administration of AR-42 followed by decitabine resulted in a stronger anti-leukemic activity in vitro and in vivo than decitabine followed by AR-42 or either drug alone. These preclinical results with AR-42 priming before decitabine administration represents a promising, novel treatment approach and a paradigm shift with regard to the combination of epigenetic-targeting compounds in AML, where decitabine has been traditionally given before HDAC inhibitors.
acute myeloid leukemia; HDACI; AR-42; decitabine; miR-29b
The success of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) depends on the requirement for BCR-ABL1 kinase activity in CML progenitors. However, CML quiescent HSCs are TKI resistant and represent a BCR-ABL1 kinase–independent disease reservoir. Here we have shown that persistence of leukemic HSCs in BM requires inhibition of the tumor suppressor protein phosphatase 2A (PP2A) and expression — but not activity — of the BCR-ABL1 oncogene. Examination of HSCs from CML patients and healthy individuals revealed that PP2A activity was suppressed in CML compared with normal HSCs. TKI-resistant CML quiescent HSCs showed increased levels of BCR-ABL1, but very low kinase activity. BCR-ABL1 expression, but not kinase function, was required for recruitment of JAK2, activation of a JAK2/β-catenin survival/self-renewal pathway, and inhibition of PP2A. PP2A-activating drugs (PADs) markedly reduced survival and self-renewal of CML quiescent HSCs, but not normal quiescent HSCs, through BCR-ABL1 kinase–independent and PP2A-mediated inhibition of JAK2 and β-catenin. This led to suppression of human leukemic, but not normal, HSC/progenitor survival in BM xenografts and interference with long-term maintenance of BCR-ABL1–positive HSCs in serial transplantation assays. Targeting the JAK2/PP2A/β-catenin network in quiescent HSCs with PADs (e.g., FTY720) has the potential to treat TKI-refractory CML and relieve lifelong patient dependence on TKIs.
We evaluated the impact of busulfan dose-intensity in patients undergoing reduced toxicity/intensity conditioning allogeneic transplantation in a multicenter retrospective study of 112 consecutive patients. Seventy-five patients were conditioned with busulfan (0.8 mg/kg/dose IV × 8 doses), fludarabine (30mg/m2/day, days −7 to −3), and 6mg/kg of ATG (RIC group), while 37 patients received a more-intense conditioning with busulfan (130mg/m2/day IV, days −6 to −3), fludarabine (40mg/m2/day, days −6 to −3), and 6mg/kg of ATG (RTC group). At baseline both groups were matched for median age, unrelated donor allografts, and HLA-mismatched allografts. More patients in RIC group had high-risk disease, and higher median co-morbidity index. There were no graft rejections. Median time to neutrophil (17 vs. 15 days; p=0.003) and platelet engraftment (16 vs. 11 days; p<0.001) was significantly longer in the RIC group. RTC group had significantly more bacterial (62.2% vs. 32%; p=0.004) and fungal infections (13.5% vs. 1.3% p=0.01). For RIC and RTC groups rates of grade II-IV acute GVHD (34% vs. 40%; p-value=0.54), and chronic GVHD (45% vs. 57%; p-value=0.30) were not significantly different. In similar order at 1-year the cumulative-incidence of non-relapse mortality (NRM) (12% vs. 21%; p-value=0.21) and relapse rates (38% vs. 39%; p=0.96) were not significantly different. Patients in RIC and RTC groups had similar 1-year overall survival (61% vs. 50% p=0.11) and progression free survival (50% vs. 36% p-value=0.39). Our data suggest that merits of higher busulfan dose-intensity in the context of fludarabine/busulfan-based RTC may be offset by higher early morbidity.
Fludarabine; busulfan; thymoglobulin; busulfan dose; allogeneic stem cell transplantation; graft-versus-host disease
Advances in whole genome profiling have revolutionized the cancer research field, but at the same time have raised new bioinformatics challenges. For next generation sequencing (NGS), these include data storage, computational costs, sequence processing and alignment, delineating appropriate statistical measures, and data visualization. Currently there is a lack of workflows for efficient analysis of large, MethylCap-seq datasets containing multiple sample groups.
The NGS application MethylCap-seq involves the in vitro capture of methylated DNA and subsequent analysis of enriched fragments by massively parallel sequencing. The workflow we describe performs MethylCap-seq experimental Quality Control (QC), sequence file processing and alignment, differential methylation analysis of multiple biological groups, hierarchical clustering, assessment of genome-wide methylation patterns, and preparation of files for data visualization.
Here, we present a scalable, flexible workflow for MethylCap-seq QC, secondary data analysis, tertiary analysis of multiple experimental groups, and data visualization. We demonstrate the experimental QC procedure with results from a large ovarian cancer study dataset and propose parameters which can identify problematic experiments. Promoter methylation profiling and hierarchical clustering analyses are demonstrated for four groups of acute myeloid leukemia (AML) patients. We propose a Global Methylation Indicator (GMI) function to assess genome-wide changes in methylation patterns between experimental groups. We also show how the workflow facilitates data visualization in a web browser with the application Anno-J.
This workflow and its suite of features will assist biologists in conducting methylation profiling projects and facilitate meaningful biological interpretation.
Acute myeloid leukemia (AML) is a disease characterized by uncontrolled proliferation of clonal neoplastic hematopoietic precursor cells. This leads to the disruption of normal hematopoiesis and bone marrow failure. Major breakthroughs in the past have contributed to our understanding of the genetic failures and the changed biology in AML cells that underlie the initiation and progression of the disease. It is now recognized that not only genetic but also epigenetic alterations are similarly important in this process. Since these alterations do not change the DNA sequences and are pharmacologically reversible, they have been regarded as optimal targets for what is now known as epigenetic therapy. In this review, we will discuss our current understanding of normal epigenetic processes, outline our knowledge of epigenetic alterations in AML, and discuss how this information is being used to improve current therapy of this disease.
Advances in whole genome profiling have revolutionized the cancer research field, but at the same time have raised new bioinformatics challenges. For next generation sequencing (NGS), these include data storage, computational costs, sequence processing and alignment, delineating appropriate statistical measures, and data visualization. The NGS application MethylCap-seq involves the in vitro capture of methylated DNA and subsequent analysis of enriched fragments by massively parallel sequencing. Here, we present a scalable, flexible workflow for MethylCap-seq Quality Control, secondary data analysis, tertiary analysis of multiple experimental groups, and data visualization. This workflow and its suite of features will assist biologists in conducting methylation profiling projects and facilitate meaningful biological interpretation.
next generation sequencing; DNA methylation; epigenetics; cancer; data analysis; data visualization
To determine the frequency of TET2 mutations, their associations with clinical and molecular characteristics and outcome, and the associated gene- and microRNA-expression signatures in patients with primary cytogenetically normal acute myeloid leukemia (CN-AML).
Patients and Methods
Four-hundred twenty-seven patients with CN-AML were analyzed for TET2 mutations by polymerase chain reaction and direct sequencing and for established prognostic gene mutations. Gene- and microRNA-expression profiles were derived using microarrays.
TET2 mutations, found in 23% of patients, were associated with older age (P < .001) and higher pretreatment WBC (P = .04) compared with wild-type TET2 (TET2-wt). In the European LeukemiaNet (ELN) favorable-risk group (patients with CN-AML who have mutated CEBPA and/or mutated NPM1 without FLT3 internal tandem duplication [FLT3-ITD]), TET2-mutated patients had shorter event-free survival (EFS; P < .001) because of a lower complete remission (CR) rate (P = .007), and shorter disease-free survival (DFS; P = .003), and also had shorter overall survival (P = .001) compared with TET2-wt patients. TET2 mutations were not associated with outcomes in the ELN intermediate-I–risk group (CN-AML with wild-type CEBPA and wild-type NPM1 and/or FLT3-ITD). In multivariable models, TET2 mutations were associated with shorter EFS (P = .004), lower CR rate (P = .03), and shorter DFS (P = .05) only among favorable-risk CN-AML patients. We identified a TET2 mutation-associated gene-expression signature in favorable-risk but not in intermediate-I–risk patients and found distinct mutation-associated microRNA signatures in both ELN groups.
TET2 mutations improve the ELN molecular-risk classification in primary CN-AML because of their adverse prognostic impact in an otherwise favorable-risk patient subset. Our data suggest that these patients may be candidates for alternative therapies.
Lenalidomide is effective in myeloma and low-risk myelodysplastic syndromes with deletion 5q. We report results of a phase I dose-escalation trial of lenalidomide in relapsed or refractory acute leukemia.
Patients and Methods
Thirty-one adults with acute myeloid leukemia (AML) and four adults with acute lymphoblastic leukemia (ALL) were enrolled. Lenalidomide was given orally at escalating doses of 25 to 75 mg daily on days 1 through 21 of 28-day cycles to determine the dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD), as well as to provide pharmacokinetic and preliminary efficacy data.
Patients had a median age of 63 years (range, 22 to 79 years) and a median of two prior therapies (range, one to four therapies). The DLT was fatigue; 50 mg/d was the MTD. Infectious complications were frequent. Plasma lenalidomide concentration increased proportionally with dose. In AML, five (16%) of 31 patients achieved complete remission (CR); three of three patients with cytogenetic abnormalities achieved cytogenetic CR (none with deletion 5q). Response duration ranged from 5.6 to 14 months. All responses occurred in AML with low presenting WBC count. No patient with ALL responded. Two of four patients who received lenalidomide as initial therapy for AML relapse after allogeneic transplantation achieved durable CR after development of cutaneous graft-versus-host disease, without donor leukocyte infusion.
Lenalidomide was safely escalated to 50 mg daily for 21 days, every 4 weeks, and was active with relatively low toxicity in patients with relapsed/refractory AML. Remissions achieved after transplantation suggest a possible immunomodulatory effect of lenalidomide, and results provide enthusiasm for further studies in AML, either alone or in combination with conventional agents or other immunotherapies.
Case: A 65-year-old male who was previously in good health presented to his primary care physician with increasing fatigue over several months. He was found to be anemic (hemoglobin 7.5 mg/dL) and neutropenic (absolute neutrophil count 1000/μL). Further laboratory investigation showed an elevated erythropoietin level and normal iron stores. Bone marrow biopsy revealed dysplasia in two lineages and 8% blasts. Cytogenetic studies showed a clone with loss of 7q. He required red blood cell transfusions approximately every 2 weeks. He was started on hypomethylating agent treatment and referred for consultation regarding the role of hematopoietic stem cell transplantation. HLA typing results demonstrated that he had an HLA-identical sibling.
Advances in the treatment of myelodysplastic syndromes (MDSs) over the last decade have given patients and their hematologists a multitude of treatment options. Therapeutic options now exist that reduce disease-related symptoms, improve quality of life, and alter the natural history of the disease. Three drugs are now specifically Food and Drug Administration-approved for treatment of MDS: (1) azacitidine, (2) decitabine, and (3) lenalidomide. Clinical results with each of these agents, plus results with immunosuppressive therapy, are reviewed to guide clinical decision making. Although each therapy has made a substantial impact in improving the care of patients with MDS, unfortunately MDS treatment in 2010 ultimately fails in most patients, but these therapies provide a foundation on which we can build to further improve outcomes.
To simultaneously quantify intracellular nucleoside triphosphate (NTP) and deoxynucleoside triphosphate (dNTP) pools and to assess their changes produced by interfering with ribonucleotide reductase (RNR) expression in leukemia cells.
A HPLC-MS/MS system was used to quantify intracellular NTP and dNTP pools.
The assay was linear between 50 nM, the lower limit of quantification (LLOQ), and 10 μMin cell lysate. The within-day coefficients of variation (CVs, n=5) were found to be 12.0–18.0% at the LLOQ and 3.0–9.0% between 500 and 5,000 nM for dNTPs and 8.0–15.0% and 2.0–6.0% for NTPs. The between-day CVs (n=5) were 9.0–13.0% and 3.0–11.0% for dNTPs and 9.0–13.0% and 3.0–6.0% for NTPs. The within-day accuracy values were 93.0–119.0% for both NTPs and dNTPs. ATP overlapped with dGTP and they were analyzed as a composite. This method was applied to measure basal intracellular dNTPs/NTPs in five leukemia cell lines exposed to the RNR antisense GTI-2040. Following drug treatment, dCTP and dATP levels were found to decrease significantly in MV4-11 and K562 cells. Additionally, perturbation of dNTP/NTP levels in bone marrow sample of a patient treated with GTI-2040 was detected.
This method provides a practical tool to measure intracellular dNTP/NTP levels in cells and clinical samples.
dNTP/NTP levels; GTI-2040; LC-MS/MS
Inhibition of ribonucleotide reductase reduces the availability of the endogenous pool of deoxycytidine and may increase cytarabine (AraC) cytotoxicity. We performed a phase I dose escalation trial of AraC combined with GTI-2040, a 20-mer antisense oligonucleotide shown in preclinical studies to decrease levels of the R2 subunit of ribonucleotide reductase, to determine the maximum tolerated dose in adults with relapsed/refractory acute myeloid leukemia.
Twenty-three adults (ages 18–59 years) were enrolled in this dose escalation phase I trial, receiving high-dose AraC twice daily combined with infusional GTI-2040. An ELISA-based assay measured plasma and intracellular concentrations of GTI-2040. R2 protein changes were evaluated by immunoblotting in pretreatment and post-treatment bone marrow samples.
The maximum tolerated dose was 5 mg/kg/d GTI-2040 (days 1–6) and 3 g/m2/dose AraC every 12 hours for 8 doses. Neurotoxicity was dose limiting. Eight patients (35%) achieved complete remission. Mean bone marrow intracellular concentration of GTI-2040 were higher at 120 hours than at 24 hours from the start of GTI-2040 (P = 0.002), suggesting intracellular drug accumulation over time. Reductions in bone marrow levels of R2 protein (>50%) were observed at 24 and 120 hours. Higher baseline R2 protein expression (P = 0.03) and reductions after 24 hours of GTI-2040 (P = 0.04) were associated with complete remission.
GTI-2040 and high-dose AraC were coadministered safely with successful reduction of the intended R2 target and encouraging clinical results. The clinical efficacy of this combination will be tested in an upcoming phase II study.
Cancer is associated with immune deficiency, but the biologic basis of this is poorly defined. Here we demonstrate that impaired actin polymerization results in CD4+ and CD8+ T cells from patients with chronic lymphocytic leukemia (CLL) exhibiting defective immunological synapse formation with APCs. Although this synapse dysfunction was in part a result of the CLL cells having poor APC function, defective actin polymerization was also identified in T cells from patients with CLL. We further demonstrate that, following contact with CLL cells, defects in immune synapse formation were induced in healthy allogeneic T cells. This required direct contact and was inhibited by blocking adhesion molecules on CLL B cells. In T cells from patients with CLL and in T cells from healthy individuals that had been in contact with CLL cells, recruitment of key regulatory proteins to the immune synapse was inhibited. Treatment of autologous T cells and CLL cells with the immunomodulating drug lenalidomide resulted in improved synapse formation. These results define what we believe to be a novel immune dysfunction in T cells from patients with CLL that has implications for both autologous and allogeneic immunotherapy approaches and identifies repair of immune synapse defects as an essential step in improving cancer immunotherapy approaches.
DNA hypermethylation is a common finding in malignant cells and has been explored as a therapeutic target for hypomethylating agents (e.g., decitabine). Detection of changes in DNA methylation might serve as a pharmacodynamic endpoint to establish the biological activity of these agents and predict clinical response. We developed and validated a rapid, sensitive and specific LC-MS/MS method for determination of global DNA methylation (GDM) in vitro and in vivo. Ratios of 5-methyl-2′-deoxycytidine (5mdC) to the internal standard 2-deoxyguanosine (2dG) in mass signal were used to quantify GDM levels. The assay was validated in a linear range from 40 fmol to 200 pmol 5mdC. The intra-day precision values ranged from 2.8 to 9.9% and the inter-day values from 1.1 to 15.0%. The accuracy of the assay varied between 96.7 and 109.5%. This method was initially applied for characterization of decitabine-induced GDM changes in in-vitro-treated leukemia cells. Following exposure to 2.5 μM decitabine, GDM decreased to ∼50% of the baseline value. The clinical applicability of this method was then demonstrated in bone marrow samples from patients with acute myeloid leukemia treated with decitabine. Our data support the use of our LC-MS/MS method for clinical pharmacodynamic determination of changes in GDM in vivo.