Therapy related leukemias: susceptibility, prevention and treatment

Pyrazole-Enriched Cationic Nanoparticles Induced Early- and Late-Stage Apoptosis in Neuroblastoma Cells at Sub-Micromolar Concentrations

Neuroblastoma (NB) is a severe form of tumor occurring mainly in young children and originating from nerve cells found in the abdomen or next to the spine. NB needs more effective and safer treatments, as the chance of survival against the aggressive form of this disease are very small. Moreover, when current treatments are successful, they are often responsible for unpleasant health problems which compromise the future and life of surviving children. As reported, cationic macromolecules have previously been found to be active against bacteria as membrane disruptors by interacting with the negative constituents of the surface of cancer cells, analogously inducing depolarization and permeabilization, provoking lethal damage to the cytoplasmic membrane, and cause loss of cytoplasmic content and consequently, cell death. Here, aiming to develop new curative options for counteracting NB cells, pyrazole-loaded cationic nanoparticles (NPs) (BBB4-G4K and CB1H-P7 NPs), recently reported as antibacterial agents, were assayed against IMR 32 and SHSY 5Y NB cell lines. Particularly, while BBB4-G4K NPs demonstrated low cytotoxicity against both NB cell lines, CB1H-P7 NPs were remarkably cytotoxic against both IMR 32 and SHSY 5Y cells (IC50 = 0.43–0.54 µM), causing both early-stage (66–85%) and late-stage apoptosis (52–65%). Interestingly, in the nano-formulation of CB1H using P7 NPs, the anticancer effects of CB1H and P7 were increased by 54–57 and 2.5–4-times, respectively against IMR 32 cells, and by 53–61 and 1.3–2 times against SHSY 5Y cells. Additionally, based on the IC50 values, CB1H-P7 was also 1-12-fold more potent than fenretinide, an experimental retinoid derivative in a phase III clinical trial, with remarkable antineoplastic and chemopreventive properties. Collectively, due to these results and their good selectivity for cancer cells (selectivity indices = 2.8–3.3), CB1H-P7 NPs represent an excellent template material for developing new treatment options against NB.

Competing mortality risk from second primary malignancy in bladder cancer patients following radical cystectomy: Implications for survivorship

INTRODUCTION

Muscle-invasive bladder cancer (BC) often occurs in patients with competing mortality risks, while also being associated with the highest rate of second primary nonurothelial cancers (SNUC) of all solid malignancies. We investigated the incidence, risk factors, and timing of SNUC as a competing mortality risk factor in patients with BC who were treated with curative intent radical cystectomy (RC).

METHODS

We performed a retrospective cohort study assessing patients who underwent RC for cT2-4 N0M0 BC from January 1, 2005 to December 31, 2018 at a single, high volume tertiary care referral center. The Fine-Gray multivariable regression model was used to evaluate predictive factors for SNUC. Cumulative incidence of mortality (CIM) was estimated with modified Kaplan-Meier analysis.

RESULTS

The median follow-up time for the 693 patients who underwent RC was 3.7 years (interquartile range [IQR] 1.9-5.9 years). SNUC developed in 85 (12.3%) patients at a median 3.0 years post-RC (IQR 1.2-5.5 years). On multivariable analysis, the only significant predictor for developing SNUC was freedom from BC recurrence or metastasis (HR 1.54, 95% CI 1.12-1.76, P = 0.019). The most common SNUCs were primary lung cancer (24, 3.2% of cohort) and colon cancer (9, 1.3% of cohort). BC surveillance imaging diagnosed SNUC in 35/52 (67.3%) patients with solid-organ visceral primaries. The overall mortality rate for any SNUC was 38.8%, with the 3 most lethal cancer types being pancreatic, lung, and colon (62.5%, 54.2%, and 44.4% mortality, respectively). The incidence of SNUC uniformly increased postoperatively, with a cumulative incidence of 22.1% (95% CI, 16.8-27.9%) at 12-years post-RC. 163 patients (23.5%) died from BC, 33 patients (4.8%) died from SNUC, and 94 patients (13.6%) died from other causes. While the CIM for BC plateaued around 5-years post-RC at 24%, the incidence of other-cause mortality uniformly rose throughout the postoperative period. By post-RC year 9 there was no significant difference in CIM between BC (CIM 27.2%, 95% CI, 23.5-31.1%) and other-causes (CIM 20.0%, 95% CI, 15.8-24.6%).

CONCLUSIONS

The cumulative incidence of SNUC at 12-years post-RC was 22%, with the majority identified on BC surveillance imaging. While BC mortality plateaued around 5-years post-RC, mortality related to SNUC or other causes rose steadily in the postoperative period. These data have clinical significance with regards to patient counseling, survivorship and oncologic surveillance in the highly comorbid muscle-invasive BC population.

Risk and outcome of second primary malignancy in patients with classical Hodgkin lymphoma

BACKGROUND

Hodgkin lymphoma survivors demonstrated increased risk of secondary primary malignancies (SPMs), but comprehensive analysis of the risk and outcome of SPMs in classical Hodgkin lymphoma (cHL) patients has not yet been reported.

METHODS

Patients with cHL from 1975 to 2017 were identified from the Surveillance, Epidemiology and End Results (SEER) database. Standardized incidence ratios were calculated for the risk of solid and hematologic SPMs in cHL patients compared to the general population. The outcome of cHL patients developing SPMs were assessed by performing survival, competing risks regression, and cox proportional regression analyses.

RESULTS

In a follow-up of 26,493 cHL survivors for 365,156 person years, 3866 (14.59%) secondary cancers were identified, with an standardized incidence ratio of 2.09 (95% CI: 2.02-2.15). The increased risk was still notable after follow-up of 10 years or more, and the risk is more pronounced for patients with female gender, younger age, advanced stage, chemotherapy, and radiation therapy. The overall survival is worse for cHL patients with SPMs after 11 years of follow-up (P < .0001). The main cause of death for cHL patients with SPMs is not cHL but other causes including SPMs. Multivariate Cox regression analysis confirmed SPMs as an independently adverse prognostic factor for cHL survivors (hazard ratio, 1.13; 95% CI, 1.05-1.21, P = .001).

CONCLUSIONS

There is a significantly increased risk of developing SPMs for cHL survivors. The overall survival is worse for cHL patients and SPMs is an independent prognostic factor for cHL.

Treatment-Associated Acute Lymphoblastic Leukemia Following Autologous Hematopoietic Stem Cell Transplant and Lenalidomide Maintenance in Patients With Multiple Myeloma

Secondary malignancies including leukemia are an increasing concern in patients with prior primary malignancies treated with alkylating agents or topoisomerase II inhibitors. These can also be referred to as therapy-related leukemia. Therapy-related leukemia most commonly results in myelodysplastic syndrome or acute myeloid leukemia. The alkylating agent can cause chromosomal aberrations typically manifest as deletions in chromosome 11 or loss of part of complete loss of chromosomes 5 and 7. Conversely, acute lymphoblastic leukemia (ALL) has been described following maintenance therapy with immunomodulatory (IMiD) drugs pomalidomide, thalidomide, and lenalidomide. We present a case of a 71-year-old man with a history of multiple myeloma (MM) maintained on lenalidomide after stem cell transplant who presented with treatment-associated ALL. At time of leukemic presentation, chromosomal analysis showed a near-triploid clone consistent with masked double low hyplodiploidy which is associated with a poor prognosis. The patient had a deletion of the long arm of chromosome 5 which has been described in prior case reports with ALL secondary to lenalidomide therapy. There are explicit mechanisms in the literature, which have been attributed to development of ALL after exposure to thalidomide or lenalidomide. At time of submission, there are 20 cases described in the literature linking ALL to IMiD drugs. We describe a case and review the mechanisms of lenalidomide-associated ALL.

A Proposed Link Between Acute Thymic Involution and Late Adverse Effects of Chemotherapy

Epidemiologic data suggest that cancer survivors tend to develop a protuberant number of adverse late effects, including second primary malignancies (SPM), as a result of cytotoxic chemotherapy. Besides the genotoxic potential of these drugs that directly inflict mutational burden on genomic DNA, the precise mechanisms contributing to SPM development are poorly understood. Cancer is nowadays perceived as a complex process that goes beyond the concept of genetic disease and includes tumor cell interactions with complex stromal and immune cell microenvironments. The cancer immunoediting theory offers an explanation for the development of nascent neoplastic cells. Briefly, the theory suggests that newly emerging tumor cells are mostly eliminated by an effective tissue immunosurveillance, but certain tumor variants may occasionally escape innate and adaptive mechanisms of immunological destruction, entering an equilibrium phase, where immunologic tumor cell death "equals" new tumor cell birth. Subsequent microenvironmental pressures and accumulation of helpful mutations in certain variants may lead to escape from the equilibrium phase, and eventually cause an overt neoplasm. Cancer immunoediting functions as a dedicated sentinel under the auspice of a highly competent immune system. This perspective offers the fresh insight that chemotherapy-induced thymic involution, which is characterized by the extensive obliteration of the sensitive thymic epithelial cell (TEC) compartment, can cause long-term defects in thymopoiesis and in establishment of diverse T cell receptor repertoires and peripheral T cell pools of cancer survivors. Such delayed recovery of T cell adaptive immunity may result in prolonged hijacking of the cancer immunoediting mechanisms, and lead to development of persistent and mortal infections, inflammatory disorders, organ-specific autoimmunity lesions, and SPMs. Acknowledging that chemotherapy-induced thymic involution is a potential risk factor for the emergence of SPM demarcates new avenues for the rationalized development of pharmacologic interventions to promote thymic regeneration in patients receiving cytoreductive chemotherapies.

Monocytosis and Multiple Myeloma: treatment-related acute leukaemia?

Background

Therapy-related acute monocytic leukemias in patients with plasma cell dyscrasias are infrequent.

Case presentation

We here present a case of a 60 year old female who developed an acute monocytic leukemia two years after the diagnosis of multiple myeloma. She was treated with an alkylating agent and bortezomib before undergoing a hematopoietic stem cell transplantation. She suffered of multiple severe infections until her immune system was adequately reconstituted. A year afterwards, she presented signs of deterioration unrelated to the MM, with pancytopenia. The bone marrow aspirate failed to show a prominent blast population. The diagnosis of AML was confirmed after a bone marrow biopsy.

Discussion

The development of acute leukaemia after treatment for multiple myeloma is a well characterized phenomenon. Most frequently, patients develop a myelomonocytic leukemia. Similarly, synchronous acute myeloid leukemias are myelomonocytic or myeloblastic. Rarely synchronous AMLs are monocytic. The development of such suggests a dysfunctional bone marrow microenvironment.

Childhood Cancer: Occurrence, Treatment and Risk of Second Primary Malignancies

Cancer represents the leading cause of disease-related death and treatment-associated morbidity in children with an increasing trend in recent decades worldwide. Nevertheless, the 5-year survival of childhood cancer patients has been raised impressively to more than 80% during the past decades, primarily attributed to improved diagnostic technologies and multiagent cytotoxic regimens. This strong benefit of more efficient tumor control and prolonged survival is compromised by an increased risk of adverse and fatal late sequelae. Long-term survivors of pediatric tumors are at the utmost risk for non-carcinogenic late effects such as cardiomyopathies, neurotoxicity, or pneumopathies, as well as the development of secondary primary malignancies as the most detrimental consequence of genotoxic chemo- and radiotherapy. Promising approaches to reducing the risk of adverse late effects in childhood cancer survivors include high precision irradiation techniques like proton radiotherapy or non-genotoxic targeted therapies and immune-based treatments. However, to date, these therapies are rarely used to treat pediatric cancer patients and survival rates, as well as incidences of late effects, have changed little over the past two decades in this population. Here we provide an overview of the epidemiology and etiology of childhood cancers, current developments for their treatment, and therapy-related adverse late health consequences with a special focus on second primary malignancies.

Second malignancies after treatment of childhood non-Hodgkin lymphoma: a report of the Berlin-Frankfurt-Muenster study group

Second malignant neoplasms pose a concern for survivors of childhood cancer. We evaluated incidence, type and risk factors for second malignant neoplasms in patients included in Berlin-Frankfurt-Muenster protocols for childhood non-Hodgkin lymphoma. 3590 patients <15 years of age at diagnosis registered between 01/1981 and 06/2010 were analyzed. Second malignant neoplasms were reported by the treating institutions and the German Childhood Cancer Registry. After median follow-up of 9.4 years (Quartile, Q1 6.7 and Q3 12.1) 95 second malignant neoplasms were registered (26 carcinomas including 9 basal cell carcinomas, 21 acute myeloid leukemias/myelodysplastic syndromes, 20 lymphoid malignancies, 12 CNS-tumors, and 16 other). Cumulative incidence at 20 years was 5.7±0.7%, standard incidence ratio excluding basal cell carcinomas was 19.8 (95% CI 14.5-26.5). Median time from initial diagnosis to second malignancy was 8.7 years (range: 0.2-30.3). Acute-lymphoblastic-leukemia-type therapy, cumulative anthracycline dose, and cranial radiotherapy for brain tumor-development were significant risk factors in univariate analysis only. In multivariate analysis including risk factors significant in univariate analysis, female sex (HR 1.87, 95% CI 1.23-2.86, p=0.004), CNS-involvement (HR 2.24, 95% CI 1.03-4.88, p=0.042), lymphoblastic lymphoma (HR 2.60, 95% CI 1.69-3.97, p<0.001), and cancer-predisposing condition (HR 11.2, 95% CI 5.52-22.75, p<0.001) retained an independent risk. Carcinomas were the most frequent second malignant neoplasms after non-Hodgkin lymphoma in childhood followed by acute myeloid leukemia and lymphoid malignancies. Female sex, lymphoblastic lymphoma, CNS-involvement, or/and known cancer-predisposing condition were risk factors for second malignant neoplasm-development. Our findings set the basis for individualized long-term follow-up and risk assessment of new therapies.

Lenalidomide-Associated Secondary B-Lymphoblastic Leukemia/Lymphoma-A Unique Entity

OBJECTIVES

Autologous stem cell transplant with lenalidomide maintenance therapy has greatly improved the relapse-free and overall survival rates of patients with multiple myeloma but also has been associated with an increased risk of secondary B-lymphoblastic leukemia/lymphoma (B-ALL).

METHODS

We report a comprehensive review of the clinicopathologic features of 2 patients with multiple myeloma who developed secondary B-ALL during lenalidomide maintenance.

RESULTS

Our observations showed that the disease may initially present with subtle clinical, morphologic, and flow-cytometric findings. The flow cytometry findings in such cases may initially mimic an expansion of hematogones with minimal immunophenotypic variation. Both patients achieved complete remission of secondary B-ALL after standard chemotherapy; however, one patient continues to have minimal residual disease, and the other experienced relapse. Next-generation sequencing of the relapse specimen showed numerous, complex abnormalities, suggesting clonal evolution.

CONCLUSIONS

Our findings suggest the need for increased awareness and further study of this unique form of secondary B-ALL.

Dendrimer Nanodevices and Gallic Acid as Novel Strategies to Fight Chemoresistance in Neuroblastoma Cells

Human neuroblastoma (NB), a pediatric tumor inclined to relapse, after an initial response to therapy, usually develops resistance. Since several chemotherapeutics exert anticancer effect by increasing reactive oxygen species (ROS), NB cells overproduce antioxidant compounds becoming drugs-resistant. A strategy to sensitize NB cells to chemotherapy involves reducing their antioxidant defenses and inducing ROS overproduction. Concerning this, although affected by several issues that limit their clinical application, antioxidant/pro-oxidant polyphenols, such as gallic acid (GA), showed pro-oxidant anti-cancer effects and low toxicity for healthy cells, in several kind of tumors, not including NB. Herein, for the first time, free GA, two GA-dendrimers, and the dendrimer adopted as GA reservoir were tested on both sensitive and chemoresistant NB cells. The dendrimer device, administered at the dose previously found active versus sensitive NB cells, induced ROS-mediated death also in chemoresistant cells. Free GA proved a dose-dependent ROS-mediated cytotoxicity on both cell populations. Intriguingly, when administered in dendrimer formulations at a dose not cytotoxic for NB cells, GA nullified any pro-oxidant activity of dendrimer. Unfortunately, due to GA, nanoformulations were inactive on NB cells, but GA resized in nanoparticles showed considerable ability in counteracting, at low dose, ROS production and oxidative stress, herein induced by the dendrimer.

B-cell acute lymphoblastic leukemia as a secondary malignancy following diffuse large B-cell lymphoma

Secondary acute lymphoblastic leukemia (ALL) is a rare disease that has not been well characterized compared with secondary myelodysplastic syndrome or secondary acute myeloid leukemia. We present a report of two patients who developed ALL following complete remission of diffuse large B-cell lymphoma (DLBCL). The first case is more consistent with a therapy- related ALL as a PCR analysis of bone marrow aspirate revealed a distinct clone and the mixed-lineage leukemia gene rearrangement, commonly associated with exposure to topoisomerase II inhibitors. The second case is more consistent with clonal evolution given positive MYC and BCL2 fusion signals in the original diagnosis of DLBCL and the secondary ALL.

Multiple myeloma secondary to acute lymphoblastic leukemia: A case report

RATIONALE

Acute lymphoblastic leukemia (ALL) secondary to multiple myeloma (MM) is rare. Here we report a rare case of secondary ALL transformed from MM.

PATIENT CONCERNS

A 64-year-old woman was diagnosed as MM IgG light chain type in 2001. She achieved complete remission after 2 cycles of therapy, and received maintenance therapy with thalidomide. The patient suffered from MM relapse in September 2011. Bone marrow examination showed that the percentage of primary lymphocytes was 59%, indicating ALL-L2 (Pre-B-ALL). The patient reached complete remission after 1 cycle of chemotherapy, and has been maintained for more than 6 years.

DIAGNOSES

Immunophenotyping analysis revealed that the abnormal cell population accounted for approximately 66% which expressed HLA-DR, CD4, CD22, CD33, CD34, and cCD79a. These results indicated acute B lymphoblastic leukemia. Chromosome presented 47, XX, +5, -7, +19. Leukemia fusion gene analysis demonstrated positive EVI1 and negative IgH and TCR gene rearrangement.

INTERVENTIONS

The patient accepted 1 cycle of VDCLP chemotherapy and reached complete remission, followed with consolidation therapies with VDCLP, MA, CAG and other chemotherapy regimens.

OUTCOMES

This patient has maintained CR1 of ALL for more than 6 years.

LESSONS

Even secondary lymphoblastic leukemia has been rarely reported in patients with MM, we still need perform bone marrow examination, flow cytology, and gene tests, especially during maintenance therapy.

Genomic amplification of chromosome 7 in the Doxorubicin resistant K562 cell line

Acquisition of multi-drug resistance (MDR) is a major hindrance towards the successful treatment of cancers. Over expression of a range of ATP-dependent efflux pumps, particularly ABCB1 is a widely reported mechanism of cancer cell MDR. Approximately 30% acute myeloid leukemia (AML) patients demonstrate ABCB1 over expression. Several mechanisms for up regulation of ABCB1 have been proposed. Our aim was to investigate the role of genomic amplification of the chromosome 7 region with regard to its influence on ABCB1 over expression in AML cell line. For this, we developed Doxorubicin (Dox) resistant leukemic cell line from K562 cells, demonstrating MDR phenotype. The chromosomal changes associated with the acquisition of MDR were characterized by array- based comparative genomic hybridization (aCGH) with the parental K562 cell line as the reference genome. Significant genomic gains in the chromosomal region corresponding to 7q11.21-7q22.1 were observed in Dox selected cell line. Moreover, the amplicon contains the ABCB1 gene locus at 7q21.1 with a copy number gain of >4. ABCB1 mRNA was found to be up-regulated by54-fold. Our results demonstrate that the development of MDR in K562/Dox is underlined by a genomic amplification of the chromosome 7 region harboring the ABCB1 gene.

Glutathione-mediated antioxidant response and aerobic metabolism: two crucial factors involved in determining the multi-drug resistance of high-risk neuroblastoma

Neuroblastoma, a paediatric malignant tumor, is initially sensitive to etoposide, a drug to which many patients develop chemoresistance. In order to investigate the molecular mechanisms responsible for etoposide chemoresistance, HTLA-230, a human MYCN-amplified neuroblastoma cell line, was chronically treated with etoposide at a concentration that in vitro mimics the clinically-used dose. The selected cells (HTLA-Chr) acquire multi-drug resistance (MDR), becoming less sensitive than parental cells to high doses of etoposide or doxorubicin. MDR is due to several mechanisms that together contribute to maintaining non-toxic levels of H₂O₂. In fact, HTLA-Chr cells, while having an efficient aerobic metabolism, are also characterized by an up-regulation of catalase activity and higher levels of reduced glutathione (GSH), a thiol antioxidant compound. The combination of such mechanisms contributes to prevent membrane lipoperoxidation and cell death. Treatment of HTLA-Chr cells with L-Buthionine-sulfoximine, an inhibitor of GSH biosynthesis, markedly reduces their tumorigenic potential that is instead enhanced by the exposure to N-Acetylcysteine, able to promote GSH synthesis.

Collectively, these results demonstrate that GSH and GSH-related responses play a crucial role in the acquisition of MDR and suggest that GSH level monitoring is an efficient strategy to early identify the onset of drug resistance and to control the patient's response to therapy.

Secondary malignant neoplasms, progression-free survival and overall survival in patients treated for Hodgkin lymphoma: a systematic review and meta-analysis of randomized clinical trials

Treatment intensification to maximize disease control and reduced intensity approaches to minimize the risk of late sequelae have been evaluated in newly diagnosed Hodgkin lymphoma. The influence of these interventions on the risk of secondary malignant neoplasms, progression-free survival and overall survival is reported in the meta-analysis herein, based on individual patient data from 9498 patients treated within 16 randomized controlled trials for newly diagnosed Hodgkin lymphoma between 1984 and 2007. Secondary malignant neoplasms were meta-analyzed using Peto’s method as time-to-event outcomes. For progression-free and overall survival, hazard ratios derived from each trial using Cox regression were combined by inverse-variance weighting. Five study questions (combined-modality treatment vs. chemotherapy alone; more extended vs. involved-field radiotherapy; radiation at higher doses vs. radiation at 20 Gy; more vs. fewer cycles of the same chemotherapy protocol; standard-dose chemotherapy vs. intensified chemotherapy) were investigated. After a median follow-up of 7.4 years, dose-intensified chemotherapy resulted in better progression-free survival rates (P=0.007) as compared with standard-dose chemotherapy, but was associated with an increased risk of therapy-related acute myeloid leukemia/myelodysplastic syndromes (P=0.0028). No progression-free or overall survival differences were observed between combined-modality treatment and chemotherapy alone, but more secondary malignant neoplasms were seen after combined-modality treatment (P=0.010). For the remaining three study questions, outcomes and secondary malignancy rates did not differ significantly between treatment strategies. The results of this meta-analysis help to weigh up efficacy and secondary malignancy risk for the choice of first-line treatment for Hodgkin lymphoma patients. However, final conclusions regarding secondary solid tumors require longer follow-up.

Subsequent primary malignancies after diffuse large B-cell lymphoma in the modern treatment era

With the addition of rituximab and other treatment advances, survival after diffuse large B-cell lymphoma (DLBCL) has improved, but subsequent primary malignancies (SPMs) have emerged as an important challenge for DLBCL survivorship. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for SPMs among 23 879 patients who survived at least 1 year after a first primary DLBCL diagnosed during 1989-2012, compared to the general population in California. Cumulative incidence (CMI) of SPMs, accounting for the competing risk of death, also was calculated. We found that the incidence of acute myeloid leukaemia (AML) nearly doubled in the post-rituximab era [SIR (95% CI) 4·39 (2·51-7·13) pre- (1989-2000) and 8·70 (6·62-11·22) post-rituximab (2001-2012)]. Subsequent thyroid cancer was rare pre-rituximab, but increased substantially after 2001 [0·66 (0·08-2·37) vs. 2·27(1·44-3·41)]. The 5-year CMI for all SPMs (4·77% pre- vs. 5·41% post-rituximab, P = 0·047), AML (0·15% vs. 0·41%, P = 0·003), thyroid cancer (0·03% vs. 0·15%, P = 0·003) and melanoma (0·25% vs. 0·42%, P = 0·020) were greater in DLBCL patients diagnosed in the post- versus pre-rituximab period. This study provides insight into the changing pattern of SPM occurrence after the introduction of rituximab, which may elucidate the aetiology of SPMs and should guide future cancer surveillance efforts among DLBCL patients.

The emergence of acid ceramidase as a therapeutic target for acute myeloid leukemia

INTRODUCTION

Acute myeloid leukemia (AML) is the most common adult leukemia. Only a fraction of AML patients will survive with existing chemotherapy regimens. Hence, there is an urgent and unmet need to identify novel targets and develop better therapeutics in AML. In the past decade, the field of sphingolipid metabolism has emerged into the forefront of cancer biology due to its importance in cancer cell proliferation and survival. In particular, acid ceramidase (AC) has emerged as a promising therapeutic target due to its role in neutralizing the pro-death effects of ceramide. Areas covered: This review highlights key information about AML biology as well as current knowledge on dysregulated sphingolipid metabolism in cancer and AML. We describe AC function and dysregulation in cancer, followed by a review of studies that report elevated AC in AML and compounds known to inhibit the enzyme. Expert opinion: AML has a great need for new drug targets and better therapeutic agents. The finding of elevated AC in AML supports the concept that this enzyme represents a novel and realistic therapeutic target for this common leukemia. More effort is needed towards developing better AC inhibitors for clinical use and combination treatment with existing AML therapies.

Outcomes of children, adolescents, and young adults following allogeneic stem cell transplantation for secondary acute myeloid leukemia and myelodysplastic syndromes-The MD Anderson Cancer Center experience

We conducted a retrospective analysis of outcomes for children and young adults with sAML/sMDS who underwent HSCT at our institution. Thirty-two patients (median age 20 years) with sAML (n=24) and sMDS (n=8) received HSCT between 1990 and 2013. The median time from sAML/sMDS diagnosis to HSCT was 4.1 months (range: 1.2-27.2 months). The transplant regimens were primarily busulfan based (n=19). BM was the primary donor source (n=15). Eleven recipients were transplanted with residual disease. At a median follow-up of 62.3 months (range: 0.4-250.9 months), 14 patients had disease recurrence. Acute GVHD, grade III/IV, occurred in three patients. Causes of death were as follows: disease relapse (n=12), infection (n=2), pneumonia (n=1), pulmonary hemorrhage (n=1), acute GVHD (n=1), and graft failure (n=1). A PS of ≥90% at the time of HSCT had a significant impact on PFS (P=.02). Patients achieving pretransplant primary CR (n=8) and those with sMDS and RA (n=6) had prolonged PFS (P=.04). On multivariate analysis, shorter time to transplantation (≤6 months from diagnosis of sAML/sMDS) was associated with superior OS (P=.0018) and PFS (P=.0005).

DNA Repair Capacity in Multiple Pathways Predicts Chemoresistance in Glioblastoma Multiforme

Cancer cells can resist the effects of DNA-damaging therapeutic agents via utilization of DNA repair pathways, suggesting that DNA repair capacity (DRC) measurements in cancer cells could be used to identify patients most likely to respond to treatment. However, the limitations of available technologies have so far precluded adoption of this approach in the clinic. We recently developed fluorescence-based multiplexed host cell reactivation (FM-HCR) assays to measure DRC in multiple pathways. Here we apply a mathematical model that uses DRC in multiple pathways to predict cellular resistance to killing by DNA-damaging agents. This model, developed using FM-HCR and drug sensitivity measurements in 24 human lymphoblastoid cell lines, was applied to a panel of 12 patient-derived xenograft (PDX) models of glioblastoma to predict glioblastoma response to treatment with the chemotherapeutic DNA-damaging agent temozolomide. This work showed that, in addition to changes in O⁶-methylguanine DNA methyltransferase (MGMT) activity, small changes in mismatch repair (MMR), nucleotide excision repair (NER), and homologous recombination (HR) capacity contributed to acquired temozolomide resistance in PDX models and led to reduced relative survival prolongation following temozolomide treatment of orthotopic mouse models in vivo Our data indicate that measuring the combined status of MMR, HR, NER, and MGMT provided a more robust prediction of temozolomide resistance than assessments of MGMT activity alone. Cancer Res; 77(1); 198-206. ©2016 AACR.

Lymphohematopoietic cancers induced by chemicals and other agents and their implications for risk evaluation: An overview

Lymphohematopoietic neoplasia are one of the most common types of cancer induced by therapeutic and environmental agents. Of the more than 100 human carcinogens identified by the International Agency for Research on Cancer, approximately 25% induce leukemias or lymphomas. The objective of this review is to provide an introduction into the origins and mechanisms underlying lymphohematopoietic cancers induced by xenobiotics in humans with an emphasis on acute myeloid leukemia, and discuss the implications of this information for risk assessment. Among the agents causing lymphohematopoietic cancers, a number of patterns were observed. Most physical and chemical leukemia-inducing agents such as the therapeutic alkylating agents, topoisomerase II inhibitors, and ionizing radiation induce mainly acute myeloid leukemia through DNA-damaging mechanisms that result in either gene or chromosomal mutations. In contrast, biological agents and a few immunosuppressive chemicals induce primarily lymphoid neoplasms through mechanisms that involve alterations in immune response. Among the environmental agents examined, benzene was clearly associated with acute myeloid leukemia in humans, with increasing but still limited evidence for an association with lymphoid neoplasms. Ethylene oxide and 1,3-butadiene were linked primarily to lymphoid cancers. Although the association between formaldehyde and leukemia remains controversial, several recent evaluations have indicated a potential link between formaldehyde and acute myeloid leukemia. The four environmental agents examined in detail were all genotoxic, inducing gene mutations, chromosomal alterations, and/or micronuclei in vivo. Although it is clear that rapid progress has been made in recent years in our understanding of leukemogenesis, many questions remain for future research regarding chemically induced leukemias and lymphomas, including the mechanisms by which the environmental agents reviewed here induce these diseases and the risks associated with exposures to such agents.

Mechanisms of oncogenic chromosomal translocations

Chromosome translocations are caused by inappropriate religation of two DNA double-strand breaks (DSBs) in heterologous chromosomes. These DSBs can be generated by endogenous or exogenous sources. Endogenous sources of DSBs leading to translocations include inappropriate recombination activating gene (RAG) or activation-induced deaminase (AID) activity during immune receptor maturation. Endogenous DSBs can also occur at noncanonical DNA structures or at collapsed replication forks. Exogenous sources of DSBs leading to translocations include ionizing radiation (IR) and cancer chemotherapy. Spatial proximity of the heterologous chromosomes is also important for translocations. While three distinct pathways for DNA DSB repair exist, mounting evidence supports alternative nonhomologous end joining (aNHEJ) as the predominant pathway through which the majority of translocations occur. Initiated by poly (ADP-ribose) polymerase 1 (PARP1), aNHEJ is utilized less frequently in DNA DSB repair than other forms of DSB repair. We recently found that PARP1 is essential for chromosomal translocations to occur and that small molecule PARP1 inhibitors, already in clinical use, can inhibit translocations generated by IR or topoisomerase II inhibition. These data confirm the central role of PARP1 in aNHEJ-mediated chromosomal translocations and raise the possibility of using clinically available PARP1 inhibitors in patients who are at high risk for secondary oncogenic chromosomal translocations.

Therapy-related acute myeloid leukemia and myelodysplastic syndromes in patients with Hodgkin lymphoma: a report from the German Hodgkin Study Group

Therapy-related acute myeloid leukemia and myelodysplastic syndromes (t-AML/MDS) represent severe late effects in patients treated for Hodgkin lymphoma (HL). Because more recent data are scarce, we retrospectively analyzed incidence, outcome, and risk factors for the development of t-AML/MDS after HL. A total of 11,952 patients treated for newly diagnosed HL within German Hodgkin Study Group trials between 1993 and 2009 were considered. At a median follow-up of 72 months, t-AML/MDS was diagnosed in 106/11,952 patients (0.9%). Median time from HL treatment to t-AML/MDS was 31 months. The median age of patients with t-AML/MDS was higher than in the whole patient group (43 vs 34 years, P < .0001). Patients who received 4 or more cycles of BEACOPP(escalated) had an increased risk to develop t-AML/MDS when compared with patients treated with less than 4 cycles of BEACOPP(escalated) or no BEACOPP chemotherapy (1.7% vs 0.7% vs 0.3%, P < .0001). The median overall survival (OS) for all t-AML/MDS patients was 7.2 months. However, t-AML/MDS patients proceeding to allogeneic stem cell transplantation had a significantly better outcome with a median OS not reached after a median follow-up of 41 months (P < .001).

Gingival enlargement as an early diagnostic indicator in therapy-related acute myeloid leukemia: A rare case report and review of literature

Treatment for Hodgkin's lymphoma (HL) has resulted in excellent survival rates but is associated with increased risks of secondary therapy-related acute myeloid leukemia (t-AML). Gingival enlargement associated with bleeding and ulceration is the most common rapidly appearing oral manifestations of leukemic involvement. An 8 months pregnant patient reported with generalized gingival enlargement, with localized cyanotic and necrotic papillary areas. Co-relating the hematological report with the oral lesions and her past medical history of HL, a diagnosis of t-AML secondary to treatment for HL was made by the oncologist. As oral lesions are one of the initial manifestations of acute leukemia, they may serve as a significant diagnostic indicator for the dental surgeons and their important role in diagnosing and treating such cases. Furthermore, this case report highlights the serious complication of t-AML subsequent to HL treatment and the important role that a general and oral health care professional may play in diagnosing and treating such cases.

Risks and untoward toxicities of antibody-based immunoconjugates

Antibody-based immunoconjugates are specifically targeted monoclonal antibodies that deliver a cytotoxic payload to their target. The cytotoxic agents can be highly potent drugs, radionuclides or toxins. Such molecules, referred to as antibody-drug conjugates, radioimmunoconjugates and immunotoxins, respectively, represent a promising approach for enhancing the efficacy of unconjugated (naked) antibodies for improved therapeutic results. Though tremendous progress has been achieved over the last few decades, the safety of these molecules still remains a matter of concern and a careful design is required for achieving a relatively safe toxicity profile along with therapeutic effectiveness. This review focuses on the toxicities arising from the use of these potent agents.

Genetic abnormalities and challenges in the treatment of acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematopoietic disorder in which there are too many immature blood-forming cells accumulating in the bone marrow and interfering with the production of normal blood cells. It has long been recognized that AML is a clinically heterogeneous disease characterized by a multitude of chromosomal abnormalities and gene mutations, which translate to marked differences in responses and survival following chemotherapy. The cytogenetic and molecular genetic aberrations associated with AML are not mutually exclusive and often coexist in the leukemic cells. AML is a disease of the elderly, with a mean age of diagnosis of 70 years. Adverse cytogenetic abnormalities increase with age, and within each cytogenetic group, prognosis with standard treatment worsens with age. In the past 20 years, there has been little improvement in chemotherapeutic regimens and hence the overall survival for patients with AML. A huge unmet need exists for efficacious targeted therapies for elderly patients that are less toxic than available chemotherapy regimens. The multitude of chromosomal and genetic abnormalities makes the treatment of AML a challenging prospect. A detailed understanding of the molecular changes associated with the chromosomal and genetic abnormalities in AML is likely to provide a rationale for therapy design and biomarker development. This review summarizes the variety of cytogenetic and genetic changes observed in AML and gives an overview of the clinical status of new drugs in development.

Therapy-related myeloid neoplasms in patients treated for hodgkin lymphoma

Hodgkin lymphoma (HL) is a malignancy of the lymphatic system with an incidence of 2-3/100.000/year in developed countries. With modern multi-agent chemotherapy protocols optionally combined with radiotherapy (RT), 80% to 90% of HL patients achieve long-term remission and can be considered cured. However, current standard approaches bear a considerable risk for the development of treatment-related late effects. Thus, one major focus of current clinical research in HL is reducing the incidence of these late effects that include heart failure, infertility, chronic fatigue and therapy-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/t-AML). In previous analyses, t-MDS/t-AML after treatment for HL was associated with a poor prognosis. Nearly all patients died rapidly after diagnosis. However, more recent analyses indicated an improved outcome among patients with t-MDS/t-AML who are eligible for modern anti-leukemic treatment and allogeneic stem cell transplantation (aSCT). This article gives an overview of recent reports on the incidence and the treatment of t-MDS/t-AML after HL therapy and describes the efforts currently made to reduce the risk to develop this severe late effect.

Nutlin-3 enhances sorafenib efficacy in renal cell carcinoma

The renal cell carcinoma (RCC) is one of the top 10 cancers in USA. The renal tumors are highly angiogenic and are resistant to conventional interventions, particularly radiotherapy. The advent of multi-specific tyrosine kinase inhibitor sorafenib has improved the progression-free survival in RCC, but overall survival in recurrent and metastatic RCC is still a concern that has lead to characterization of combinatorial regimens. Hence, we studied the effect of combination of nutlin-3, an MDM2 inhibitor, which increases p53 levels, and sorafenib in RCC. Sorafenib along with nutlin-3 synergistically inhibited the cell survival and enhanced caspase-3 cleavage leading to apoptosis in RCC. Nutlin-3 and sorafenib were more effective in reducing the migration of RCC, in combination than as single agents. Sorafenib and nutlin-3 decreased the phosphorylation of vascular endothelial growth factor receptor-2 (VEGFR-2) and ERK along with inducing p53 activity. The sorafenib and nutlin-3 co-treatment lead to enhanced levels of p53, p-p53, and increase in the levels of p53 pro-apoptotic effector PUMA, Bax, and decrease in the anti-apoptotic Bcl-2 levels. Importantly, our studies revealed that sorafenib alone can activate p53 in a concentration dependent manner. Thus, co-treatment of nutlin-3 with sorafenib leads to increased half-life of p53, which in turn can be activated by sorafenib, to induce downstream pro-apoptotic and anti-proliferative effects. This is the first report showing the synergistic effect of sorafenib and nutlin-3 while providing a strong clinical-translational rationale for further testing of sorafenib and nutlin-3 combinatorial regimen in human RCC.

Allogeneic stem cell transplantation in therapy-related acute myeloid leukemia and myelodysplastic syndromes: impact of patient characteristics and timing of transplant

Patients with therapy-related acute myeloid leukemia (t-AML) and myelodysplastic syndromes (t-MDS) have poor survival and high non-relapse mortality (NRM) after allogeneic stem cell transplantation. This retrospective study assessed the transplant outcomes of 29 consecutive patients with t-AML (83%) or t-MDS (17%) treated with allogeneic transplantation. The median age of patients was 51 years. Donors were mostly matched unrelated (52%), and 59% of patients received myeloablative conditioning. Two-year overall survival, event-free survival and relapse incidence were 37%, 34% and 33%; NRM was 17% at 100 days, and 32% at 2 years. Event-free survival was reduced in patients with high-risk cytogenetics (p = 0.02), Karnofsky performance status ≤ 80% (p = 0.001) and disease after induction ± consolidation (p = 0.006). NRM was higher in patients receiving > 2 therapy lines for previous cancer (p = 0.01) and in those allografted > 6 months from diagnosis (p = 0.03). In conclusion, allogeneic transplantation should be proposed timely to these patients after an accurate analysis of patient history.

Chromatin remodelling at the topoisomerase II-beta promoter is associated with enhanced sensitivity to etoposide in human neuroblastoma cell lines

Etoposide, an inhibitor of topoisomerase II, promotes DNA damage and apoptosis of cancer cells and is a component of standard therapy for neuroblastoma. Resistance to etoposide has been observed in neural tumour cells expressing lower levels of topoisomerase II. In the present study, we have examined the contribution of epigenetic modulation of gene expression in the potentiation of etoposide-mediated cytotoxicity in neuroblastoma cells. Specifically, we studied the effects of histone deacetylase inhibition with valproic acid on topoisomerase II gene expression and apoptosis in response to etoposide. Using human neuroblastoma cell lines SK-N-AS and SK-N-SH, we show that although the combination of valproic acid and etoposide promoted a reduction in growth compared to either drug alone in both cells, the effect was substantially enhanced in SK-N-AS compared to SK-N-SH cells. An increase in histone H3 acetylation and p21 expression was observed in both cell lines, however, upregulation of topoisomerase II-beta gene expression and an increase in PARP cleavage was observed in SK-N-AS cells only. Furthermore, chromatin immunoprecipitation assays revealed an increase in acetylation of histone H3 at the cognate topoisomerase II-beta gene after treatment with valproic acid in SK-N-AS cells. These results suggest a potential epigenetic mechanism of regulation of the topoisomerase II-beta gene and a possible role for its increased expression in the sensitivity of SK-N-AS neuroblastoma cells to etoposide.

Integrated genomics of susceptibility to alkylator-induced leukemia in mice

Background

Therapy-related acute myeloid leukemia (t-AML) is a secondary, generally incurable, malignancy attributable to chemotherapy exposure. Although there is a genetic component to t-AML susceptibility in mice, the relevant loci and the mechanism(s) by which they contribute to t-AML are largely unknown. An improved understanding of susceptibility factors and the biological processes in which they act may lead to the development of t-AML prevention strategies.

Results

In this work we applied an integrated genomics strategy in inbred strains of mice to find novel factors that might contribute to susceptibility. We found that the pre-exposure transcriptional state of hematopoietic stem/progenitor cells predicts susceptibility status. More than 900 genes were differentially expressed between susceptible and resistant strains and were highly enriched in the apoptotic program, but it remained unclear which genes, if any, contribute directly to t-AML susceptibility. To address this issue, we integrated gene expression data with genetic information, including single nucleotide polymorphisms (SNPs) and DNA copy number variants (CNVs), to identify genetic networks underlying t-AML susceptibility. The 30 t-AML susceptibility networks we found are robust: they were validated in independent, previously published expression data, and different analytical methods converge on them. Further, the networks are enriched in genes involved in cell cycle and DNA repair (pathways not discovered in traditional differential expression analysis), suggesting that these processes contribute to t-AML susceptibility. Within these networks, the putative regulators (e.g., Parp2, Casp9, Polr1b) are the most likely to have a non-redundant role in the pathogenesis of t-AML. While identifying these networks, we found that current CNVR and SNP-based haplotype maps in mice represented distinct sources of genetic variation contributing to expression variation, implying that mapping studies utilizing either source alone will have reduced sensitivity.

Conclusion

The identification and prioritization of genes and networks not previously implicated in t-AML generates novel hypotheses on the biology and treatment of this disease that will be the focus of future research.

Carcinosarcoma of the pleura and lung metastasized from a poorly differentiated squamous cell carcinoma of the esophagus

Transformation of a poorly differentiated squamous cell carcinoma (SCC) of the esophagus into a âcarcinosarcomaâ of the pleura and lung has never been reported and its histogenetic origin is still debated. A 48-year-old man was admitted due to progressive dysphagia and a weight loss of 5 kilograms within 2 months. Upper gastrointestinal panendoscopic biopsy revealed poorly differentiated SCC of thoracic esophagus, upper third, T4N1M1a, stage IVa. He received concurrent chemoradiotherapy (CCRT). About 9 months later, rapid progression of lung metastases and pleural effusion were found. According to the histopathological and immunohistochemical stain results, carcinosarcoma was diagnosed. Palliative therapy was given and the patient eventually died of the disease 9 months after SCC of the thoracic esophagus was diagnosed and one month after carcinosarcoma of the pleura and lung were confirmed.

A case of treatment-related myelodysplastic syndrome spontaneously resolved by drug discontinuance

Although great advancements have been witnessed in treatment results for hematopoietic tumors in recent years, development of secondary malignant tumors induced by anti-cancer drugs still remains a serious issue. We experienced a case of secondary myelodysplastic syndrome (MDS), possibly induced by cyclophosphamide (CY), which was spontaneously resolved by discontinuance of CY. A 24-year-old woman was diagnosed with follicular lymphoma in January 1998: she had developed bulky intra-abdominal lymphadenopathy, with repeated relapse and remission by several chemotherapy treatments. Remission was induced by rituximab, administered at the time of relapse in 2001, followed by administration of 50 mg/day of CY since December 2001 for the prevention of relapse. Anemia and thrombocytopenia developed around January 2003. Bone marrow aspiration revealed abnormality in two lineages and a complicated chromosomal anomaly, and the patient was diagnosed with MDS. Discontinuance of CY and administration of an anabolic steroid improved anemia and thrombocytopenia within 2 years. Bone marrow aspiration in 2006 showed improvement in morphological abnormality and disappearance of chromosomal abnormality.

Multiple distinct malignancies in dogs: 53 cases

Despite the clinical recognition of multiple distinct types of neoplasia in individual dogs, a detailed description of such cases has not recently been published. Canine oncology cases that were diagnosed with multiple, confirmed, distinct malignancies were prospectively collected for analysis. Approximately 3% of 1722 dogs that were presented to the oncology service at the Colorado State University Veterinary Medical Center were diagnosed with multiple distinct primary tumors. No significant breed or sex predisposition was apparent. Dogs with mast cell tumor, malignant melanoma, and thyroid carcinoma were significantly overrepresented and thus more likely to be diagnosed with multiple tumor types. These findings emphasize the importance of thorough, whole-body evaluation for dogs presented with mast cell tumor, malignant melanoma, and thyroid carcinoma. Furthermore, because approximately 33% of dogs that were presented with thyroid tumors were found to have additional distinct tumors, complete staging is justified in all dogs presented with thyroid tumors.

Treatment of acute myeloid leukemia patients aged more than 75 years: Results of the E-AML-01 trial of the Japanese Elderly Leukemia and Lymphoma Study Group (JELLSG)

The feasibility and effects of combination chemotherapy for very elderly patients with acute myeloid leukemia was examined in 65 patients (including previous myelodysplastic syndrome) aged 76 years or morewith a performance status of 0 - 3. Induction chemotherapy was performed with 30 mg/m2 daunorubicin on days 1 - 3, 150 mg/m2 behenoyl cytosine arabinoside on days 1 - 7, and 70 mg/m2 6-mercaptopurine with 300 mg allopurinol taken orally on days 1 - 7 (BHAC-DM). The complete remission (CR) rate was 38.5%, whereas overall survival at 2 and 5 years was 22.0% and 4.7%, respectively. Two- and 5-year survival of CR patients was 41.8% and 11.2%, respectively. The relapse rate of the 25 CR patients was 64.0% and disease-free survival at 2 and 5 years was 21.0% and 11.2%, respectively. The therapy-related mortality rate at induction was 13.8%. BHAC-DM is feasible and effective for selected very elderly acute myeloid leukemia patients.

Altered chromatin modifications in AML1/RUNX1 breakpoint regions involved in (8;21) translocation

The RUNX1/AML1 gene is the most frequent target for chromosomal translocation, and often identified as a site for reciprocal rearrangement of chromosomes 8 and 21 in patients with acute myelogenous leukemia. Virtually all chromosome translocations in leukemia show no consistent homologous sequences at the breakpoint regions. However, specific chromatin elements (DNase I and topoisomerase II cleavage) have been found at the breakpoints of some genes suggesting that structural motifs are determinant for the double strand DNA-breaks. We analyzed the chromatin organization at intron 5 of the RUNX1 gene where all the sequenced breakpoints involved in t(8;21) have been mapped. Using chromatin immunoprecipitation assays we show that chromatin organization at intron 5 of the RUNX1 gene is different in HL-60 and HeLa cells. Two distinct features mark the intron 5 in cells expressing RUNX1: a complete lack or significantly reduced levels of Histone H1 and enrichment of hyperacetylated histone H3. Strikingly, induction of DNA damage resulted in formation of t(8;21) in HL-60 but not in HeLa cells. Taken together, our results suggest that H1 depletion and/or histone H3 hyperacetylation may have a linkage with an increase susceptibility of specific chromosomal regions to undergo translocations.

The efficacy of topoisomerase II-targeted anticancer agents reflects the persistence of drug-induced cleavage complexes in cells

Genistein, a widely consumed bioflavonoid with chemopreventative properties in adults, and etoposide, a commonly prescribed anticancer drug, are well-characterized topoisomerase II poisons. Although both compounds display similar potencies against human topoisomerase IIalpha and IIbeta in vitro and induce comparable levels of DNA cleavage complexes in cultured human cells, their cytotoxic and genotoxic effects differ significantly. As determined by assays that monitored cell viability or the phosphorylation of histone H2AX, etoposide was much more toxic in CEM cells than genistein. Further studies that characterized the simultaneous treatment of cells with genistein and etoposide indicate that the differential actions of the two compounds are not related to the effects of genistein on cellular processes outside of its activity against topoisomerase II. Rather, they appear to result from a longer persistence of cleavage complexes induced by etoposide as compared to genistein. Parallel in vitro studies with purified type II enzymes led to similar conclusions regarding cleavage complex persistence. Isoform-specific differences were observed in vitro and in cells treated with etoposide. To this point, the t 1/2 of etoposide-induced DNA cleavage complexes formed with topoisomerase IIalpha in CEM cells was approximately 5 times longer than those formed with topoisomerase IIbeta. The cytotoxicity of etoposide following four treatment-recovery cycles was similar to that induced by continuous exposure to the drug over an equivalent time period. Taken together, these findings suggest that it may be possible to preferentially target topoisomerase IIalpha with etoposide by employing a schedule that utilizes pulsed drug treatment-recovery cycles.

The outcome of haemopoietic stem cell transplantation in the treatment of lymphoplasmacytic lymphoma in the UK: a British Society Bone Marrow Transplantation study

Lymphoplasmacytic lymphoma (LL) is incurable by standard therapy (median survival: 60 months). UK transplant registry data 1984-2003 identified 18 cases of histologically verified LL (median age: 50 years, range: 38-58 years). Nine patients received high dose chemotherapy [plus total body irradiation (TBI) in 1/9] and autologous peripheral blood stem cells (PBSC). Disease status at transplant was complete remission (2), partial remission (5), primary refractory (1) or relapse (1). Transplant related mortality (TRM) at 12 months was 0%. Median follow-up is 44 months with 4 year disease free survival 43% and overall survival 73%. Karnofsky performance status (KPS) is 80-100%. The nine allografted patients (median age: 49 years, range: 39-56 years) were conditioned with standard TBI (2), BEAM (2) or FLU-MEL (5) and received PBSC from HLA-matched sibling (8) or unrelated (1) donors. Disease status at transplant was partial remission (7) or primary refractory (2). TRM at 12 months was 44%. Complications included graft failure (2), grades I-II acute graft versus host disease (aGVHD) (2), grades III-IV aGVHD (3) and chronic GVHD (4). Median follow-up is 32 months with 4 year disease free survival 44% and overall survival 56%. KPS is 70-100%.

Quantitative trait loci associated with susceptibility to therapy-related acute murine promyelocytic leukemia in hCG-PML/RARA transgenic mice

Therapy-related acute myelogenous leukemia (t-AML) is an important late adverse effect of alkylator chemotherapy. Susceptibility to t-AML has a genetic component, yet specific genetic variants that influence susceptibility are poorly understood. We analyzed an F(2) intercross (n = 282 mice) between mouse strains resistant or susceptible to t-AML induced by the alkylator ethyl-N-nitrosourea (ENU) to identify genes that regulate t-AML susceptibility. Each mouse carried the hCG-PML/RARA transgene, a well-characterized initiator of myeloid leukemia. In the absence of ENU treatment, transgenic F(2) mice developed leukemia with higher incidence (79.4% vs 12.5%) and at earlier time points (108 days vs 234 days) than mice in the resistant background. ENU treatment of F(2) mice further increased incidence (90.4%) and shortened median survival (171 vs 254 days). We genotyped F(2) mice at 384 informative single nucleotide polymorphisms across the genome and performed quantitative trait locus (QTL) analysis. Thirteen QTLs significantly associated with leukemia-free survival, spleen weight, or white blood cell count were identified on 8 chromosomes. These results suggest that susceptibility to ENU-induced leukemia in mice is a complex trait governed by genes at multiple loci. Improved understanding of genetic risk factors should lead to tailored treatment regimens that reduce risk for patients predisposed to t-AML.

Influence of DNA damage and repair upon the risk of treatment related leukemia

Therapy-related myelodysplasia and acute myeloid leukemia (t-MDS/AML) are malignancies occurring after exposure to chemotherapy and/or radiotherapy. Several studies have addressed cumulative dose, dose intensity and exposure to specific agents of preceding cytotoxic therapy in relation to the risk of developing such leukemia. Since only a small percentage of patients exposed to cytotoxic therapy develop t-MDS/AML, it has been suggested that some genetic predisposition may be involved, specifically associated to polymorphisms in certain genes involved in chemotherapy/radiotherapy response - fundamentally genes intervening in drug detoxification and DNA synthesis and repair. A review is made of the genetic studies related to t-MDS/AML predisposition, focusing on the mechanistic findings of how specific chemotherapeutic drug exposure produces DNA damage and induces the chromosomal abnormalities characteristic of t-MDS/AML, the molecular pathways involved in repairing such drug induced damage, and the way in which they influence t-MDS/AML genesis. Specific issues are (a) the interaction of topoisomerase II inhibitors, alkylators and antimetabolite drugs with DNA repair mechanisms and their impact on t-MDS/AML leukemogenicity and (b) the influence of DNA polymorphisms in genes involved in DNA repair, drug metabolization and nucleotide synthesis, paying special attention to the relevance of folate metabolism. Finally, we discuss some aspects relating to study design that are most suitable for characterizing associations between drug exposure and genotypes related to t-MDS/AML risk - stressing the importance of the inclusion of chemotherapy-exposed control groups.

Outcomes of a two-drug chemotherapy regimen for intraocular retinoblastoma

BACKGROUND

Retinoblastoma is the most common intraocular tumor of childhood. Vision salvage rates in advanced cases are less than ideal, and the optimal treatment for intraocular retinoblastoma has not been established. We report the results of an institutional retinoblastoma treatment trial to determine the vision salvage rates and toxicity of a regimen combining carboplatin and etoposide with focal retinal therapy.

PROCEDURE

Twenty-nine patients diagnosed with retinoblastoma in 48 eyes were treated between 1992 and 2004 with at least six cycles of carboplatin and etoposide combined with focal retinal therapy.

RESULTS

The response rate of eyes after six cycles of chemotherapy was 85.4%. Twenty-two eyes were enucleated, but only seven eyes received EBRT. The vision salvage rate without EBRT was 82.6% for eyes with Reese-Ellsworth (R-E) groups I-IV tumors and 20% for eyes with R-E group V tumors. The vision salvage rate without EBRT for eyes with Murphree groups A and B tumors was 77.3% but was only 26.9% for eyes with groups C and D tumors. Acute side effects were minimal.

CONCLUSIONS

The combination of carboplatin and etoposide with focal therapy is a well-tolerated regimen that has acceptable vision salvage rates for R-E groups I-IV and Murphree groups A and B retinoblastoma. This combination avoids the use of EBRT and the toxicity of additional chemotherapy agents. However, patients with R-E group V and Murphree groups C and D retinoblastoma have poorer outcomes and require more intensive therapy.

Therapy-related myelodysplasia and acute myeloid leukemia following paclitaxel- and carboplatin-based chemotherapy in an ovarian cancer patient: a case report and literature review

Alkylating agents have strong leukemogenic potential. There are a number of recent acute myeloid leukemia (t-AML) cases related to previous paclitaxel exposure. These leukemias tend to be of aggressive subtypes with long-latency periods. Unlike previously reported cases, the present case was of the secondary acute megakaryoblastic myeloid leukemia (AML M7) subtype. Additionally, it did not harbor a translocation in chromosome 19. A 73-year-old woman was diagnosed with t-AML M7 with antecedent myelodysplasia. Leukemia followed a second induction of paclitaxel- and carboplatin-based chemotherapy for recurrent ovarian cancer. Her second induction began 25 months after completion of her first course of chemotherapy. The increased incidence of postpaclitaxel leukemia suggests a probable role for paclitaxel as a leukemogenic agent. It highlights the importance of assessing for leukemia risk factors prior to beginning paclitaxel therapy.

Methylation damage response in hematopoietic progenitor cells

The cellular response to methylation DNA damage was compared in multipotent CD34(+) hematopoietic stem cells and mature CD34(-) cells isolated from cord blood of the same donor. Cytofluorimetric analysis of freshly isolated cord blood cells indicated that both cell types were in the G0/G1 phase of the cell cycle. Quantitative RT-PCR identified a general trend towards high expression of several DNA repair genes in CD34(+) cells compared to their terminally differentiated CD34(-) counterparts. The overexpressed genes included members of the mismatch repair (MMR) (MSH2, MSH6, MLH1, PMS2), base excision repair (AAG, APEX), DNA damage reversal (O(6)-methylguanine DNA methyltransferase) (MGMT), and DNA double strand breaks repair pathways. These differences in gene expression were not apparent in CD34(+) and CD34(-) cells obtained following expansion of CD34(+) cells in a medium containing early acting cytokines. Early progenitor CD34(+) and early precursor CD34(-) cells form the two populations isolated under these experimental conditions, and both contain a significant proportion of cycling cells. The methylating agent N-methyl-N-nitrosourea (MNU) induced similar levels of apoptosis in these cycling CD34(+) and CD34(-) cells. Cytotoxicity required the presence of the MGMT inhibitor O(6)-benzylguanine and the timing of MNU cell death (48 and 72h) was similar in CD34(+) and CD34(-) cells. These data indicate that cycling CD34(+) and CD34(-) cells are equally sensitive to methylation damage. MGMT provides significant protection against MNU toxicity and MGMT and MMR play the expected roles in the MNU sensitivity of these cells.

Therapy-related, mixed-lineage leukaemia translocation-positive, monoblastic myeloid sarcoma of the uterus

Myeloid sarcomas are tumour masses of myeloid leukaemic cells at extramedullary sites. These tumours can, on occasion, occur without concurrent or antecedent leukaemia. Myeloid sarcomas have been described at unusual locations including the female genital tract. An unusual case of therapy-related acute myeloid leukaemia (t-AML) presenting as isolated monoblastic myeloid sarcoma of the uterus in a patient who had received adjuvant chemotherapy for breast cancer is presented. Fluorescence in situ hybridisation analysis performed on paraffin-wax-embedded tumour tissue revealed a mixed-lineage leukaemia (MLL) gene rearrangement, supporting the association of this malignancy with prior chemotherapy. This case illustrates that t-AML can rarely present as isolated extramedullary tumours, and the detection of specific chromosomal abnormalities in these myeloid sarcomas can be useful for risk assessment and guiding definitive therapy.

Mutation of cysteine residue 455 to alanine in human topoisomerase IIalpha confers hypersensitivity to quinones: enhancing DNA scission by closing the N-terminal protein gate

Several quinone-based metabolites of industrial and environmental toxins are potent topoisomerase II poisons. These compounds act by adducting the protein, and previous studies suggest that they increase levels of enzyme-associated DNA strand breaks by at least two potential mechanisms. Quinones act directly on the DNA cleavage-ligation equilibrium of topoisomerase II by inhibiting the rate of ligation. They also block the N-terminal gate of the protein, thereby stabilizing topoisomerase II in its "closed clamp" form and trapping DNA in the central annulus of the enzyme. It has been proposed that this latter activity enhances DNA cleavage by increasing the population of enzyme molecules with DNA in their active sites, but a causal relationship has not been established. In order to more fully characterize the mechanistic basis for quinone action against topoisomerase II, the present study characterized the sensitivity of human topoisomerase IIalpha carrying a Cys455-->Ala mutation (top2alphaC455A) toward quinones. Cys455 was identified as a site of quinone adduction by mass spectrometry. The mutant enzyme was approximately 1.5-2-fold hypersensitive to 1,4-benzoquinone and the polychlorinated biphenyl quinone 4'Cl-2,5pQ, but it displayed wild-type sensitivity to traditional topoisomerase II poisons. The ability of 1,4-benzoquinone to inhibit DNA ligation mediated by top2alphaC455A was similar to that of wild-type topoisomerase IIalpha. However, the quinone induced approximately 3 times the level of clamp closure with the mutant enzyme. These findings strongly support the hypothesis that the ability of quinones to block the N-terminal gate of the type II enzyme contributes to their actions as topoisomerase II poisons.

O6-methylguanine-DNA-methyltransferase (MGMT) gene therapy targeting haematopoietic stem cells: studies addressing safety issues

As haematopoietic stem cell gene therapy utilizing O(6)-methylguanine-DNA-methyltransferase has reached the clinical stage, safety-related questions become increasingly important. These issues concern insertional mutagenesis of viral vectors, the acute toxicity of pre-transplant conditioning protocols and in vivo selection regimens as well as potential genotoxic side effects of the alkylating drugs administered in this context. To address these questions, we have investigated toxicity-reduced conditioning regimens combining low-dose alkylator application with sublethal irradiation and have analysed their influence on engraftment and subsequent selectability of transduced haematopoietic stem cells. In addition, a strategy to monitor the acute and long-term genotoxic effects of drugs with high guanine-O(6) alkylating potential, such as chloroethylnitrosoureas or temozolomide is introduced. For this purpose, assays were implemented which allow an assessment of the generation and fate of primary drug-induced adducts as well as their long-term effect on chromosomal integrity at the single cell level.

Bioflavonoids as poisons of human topoisomerase II alpha and II beta

Bioflavonoids are human dietary components that have been linked to the prevention of cancer in adults and the generation of specific types of leukemia in infants. While these compounds have a broad range of cellular activities, many of their genotoxic effects have been attributed to their actions as topoisomerase II poisons. However, the activities of bioflavonoids against the individual isoforms of human topoisomerase II have not been analyzed. Therefore, we characterized the activity and mechanism of action of three major classes of bioflavonoids, flavones, flavonols, and isoflavones, against human topoisomerase IIalpha and IIbeta. Genistein was the most active bioflavonoid tested and stimulated enzyme-mediated DNA cleavage approximately 10-fold. Generally, compounds were more active against topoisomerase IIbeta. DNA cleavage with both enzyme isoforms required a 5-OH and a 4'-OH and was enhanced by the presence of additional hydroxyl groups on the pendant ring. Competition DNA cleavage and topoisomerase II binding studies indicate that the 5-OH group plays an important role in mediating genistein binding, while the 4'-OH moiety contributes primarily to bioflavonoid function. Bioflavonoids do not require redox cycling for activity and function primarily by inhibiting enzyme-mediated DNA ligation. Mutagenesis studies suggest that the TOPRIM region of topoisomerase II plays a role in genistein binding. Finally, flavones, flavonols, and isoflavones with activity against purified topoisomerase IIalpha and IIbeta enhanced DNA cleavage by both isoforms in human CEM leukemia cells. These data support the hypothesis that bioflavonoids function as topoisomerase II poisons in humans and provide a framework for further analysis of these important dietary components.

T-cell acute lymphoblastic leukemia relapsing as acute myelogenous leukemia

We present the unusual case of a 16-year-old girl with T-cell acute lymphoblastic leukemia (ALL) with an early thymocyte immunophenotype without myeloid markers, who after 13 months of complete hematological remission relapsed as acute myelogenous leukemia (AML) with minimal differentiation and died of her disease. Whether the AML represented a relapse with lineage switch of the original immature T-cell clone or a new secondary malignancy, could not be proven due to the absence of molecular or clonal markers. This report suggests that a subset of CD7+ T-cell leukemias without mature T-cell antigens (CD4-, CD8-) are minimally differentiated and can relapse as AML.

Quinone-induced enhancement of DNA cleavage by human topoisomerase IIalpha: adduction of cysteine residues 392 and 405

Several quinone-based metabolites of drugs and environmental toxins are potent topoisomerase II poisons. These compounds act by adducting the protein and appear to increase levels of enzyme-DNA cleavage complexes by at least two potentially independent mechanisms. Treatment of topoisomerase IIalpha with quinones inhibits DNA religation and blocks the N-terminal gate of the protein by cross-linking its two protomer subunits. It is not known whether these two effects result from adduction of quinone to the same amino acid residue(s) in topoisomerase IIalpha or whether they are mediated by modification of separate residues. Therefore, this study identified amino acid residues in human topoisomerase IIalpha that are modified by quinones and determined their role in the actions of these compounds as topoisomerase II poisons. Four cysteine residues were identified by mass spectrometry as sites of quinone adduction: Cys170, Cys392, Cys405, and Cys455. Mutations (Cys --> Ala) were individually generated at each position. Only mutations at Cys392 or Cys405 reduced sensitivity ( approximately 50% resistance) to benzoquinone. Top2alphaC392A and top2alphaC405A displayed faster rates ( approximately 2-fold) of DNA religation than wild-type topoisomerase IIalpha in the presence of the quinone. In contrast, as determined by DNA binding, protein clamp closing, and protomer cross-linking experiments, mutations at Cys392 and Cys405 did not affect the ability of benzoquinone to block the N-terminal gate of topoisomerase IIalpha. These findings indicate that adduction of Cys392 and Cys405 is important for the actions of quinones against the enzyme and increases levels of cleavage complexes primarily by inhibiting DNA religation.