Therapy-related leukemia: clinical characteristics and analysis of new molecular risk factors in 96 adult patients

Therapy-related myeloid neoplasms after treatment for ovarian cancer: A retrospective single-center case series

OBJECTIVE

Therapy-related myeloid neoplasms (t-MNs) are often fatal and arise as late complications of previous anticancer drug treatment. No single-center case series has examined t-MNs in epithelial ovarian cancer (EOC).

METHODS

All patients with EOC treated at Chiba University Hospital between 2000 and 2021 were included. We retrospectively analyzed the characteristics, clinical course, and outcomes of patients who developed t-MNs.

RESULTS

Among 895 cases with EOC, 814 cases were treated with anticancer drugs. The median follow-up period was 45 months (interquartile range, 27-81) months. Ten patients (1.2%) developed t-MNs (FIGO IIIA in one case, IIIC in three, IVA in one, and IVB in five). Nine patients were diagnosed with myelodysplastic syndrome and one with acute leukemia. One patient with myelodysplastic syndrome developed acute leukemia. The median time from the first chemotherapy administration to t-MN onset was 42 months (range, 21-94 months), with t-MN diagnoses resulting from pancytopenia in four cases, thrombocytopenia in three, and blast or abnormal cell morphology in four. The median number of previous treatment regimens was four (range, 1-7). Paclitaxel + carboplatin therapy was administered to all patients, gemcitabine and irinotecan combination therapy to nine, bevacizumab to eight, and olaparib to four. Six patients received chemotherapy for t-MN. All patients died (eight cancer-related deaths and two t-MN-related deaths). None of the patients was able to restart cancer treatment. The median survival time from t-MN onset was 4 months.

CONCLUSIONS

Patients with EOC who developed t-MN were unable to restart cancer treatment and had a significantly worse prognosis.

Patient Assessment and Therapy Planning Based on Homologous Recombination Repair Deficiency

Defects in genes involved in the DNA damage response cause homologous recombination repair deficiency (HRD). HRD is found in a subgroup of cancer patients for several tumor types, and it has a clinical relevance to cancer prevention and therapies. Accumulating evidence has identified HRD as a biomarker for assessing the therapeutic response of tumor cells to poly(ADP-ribose) polymerase inhibitors and platinum-based chemotherapies. Nevertheless, the biology of HRD is complex, and its applications and the benefits of different HRD biomarker assays are controversial. This is primarily due to inconsistencies in HRD assessments and definitions (gene-level tests, genomic scars, mutational signatures, or a combination of these methods) and difficulties in assessing the contribution of each genomic event. Therefore, we aim to review the biological rationale and clinical evidence of HRD as a biomarker. This review provides a blueprint for the standardization and harmonization of HRD assessments.

Role of Germline Predisposition to Therapy-Related Myeloid Neoplasms

PURPOSE OF REVIEW

Therapy-related myeloid neoplasms (t-MNs) are aggressive leukemias that develop following exposure to DNA-damaging agents. A subset of patients developing t-MN may have an inherited susceptibility to develop myeloid neoplasia. Herein, we review studies reporting t-MN and their association with a germline or inherited predisposition.

RECENT FINDINGS

Emerging evidence suggests that development of t-MN is the result of complex interactions including generation of somatic variants in hematopoietic stem cells and/or clonal selection pressure exerted by the DNA-damaging agents, and immune evasion on top of any inherited genetic susceptibility. Conventionally, alkylating agents, topoisomerase inhibitors, and radiation have been associated with t-MN. Recently, newer modalities including poly (ADP-ribose) polymerase inhibitors (PARPi) and peptide receptor radionucleotide therapy (PRRT) are associated with t-MN. At the same time, the role of pathogenic germline variants (PGVs) in genes such as BRCA1/2, BARD1, or TP53 on the risk of t-MN is being explored. Moreover, studies have shown that while cytotoxic therapy increases the risk of developing myeloid neoplasia, it may be exposing the vulnerability of an underlying germline predisposition. t-MN remains a disease with poor prognosis. Studies are needed to better define an individual's inherited neoplastic susceptibility which will help predict the risk of myeloid neoplasia in the future. Understanding the genes driving the inherited neoplastic susceptibility will lead to better patient- and cancer-specific management including choice of therapeutic regimen to prevent, or at least delay, development of myeloid neoplasia after treatment of a prior malignancy.

Homologous recombination proficiency in ovarian and breast cancer patients

Homologous recombination and DNA repair are important for genome maintenance. Genetic variations in essential homologous recombination genes, including BRCA1 and BRCA2 results in homologous recombination deficiency (HRD) and can be a target for therapeutic strategies including poly (ADP-ribose) polymerase inhibitors (PARPi). However, response is limited in patients who are not HRD, highlighting the need for reliable and robust HRD testing. This manuscript will review BRCA1/2 function and homologous recombination proficiency in respect to breast and ovarian cancer. The current standard testing methods for HRD will be discussed as well as trials leading to approval of PARPi's. Finally, standard of care treatment and synthetic lethality will be reviewed.

Mechanistic Investigation of Site-specific DNA Methylating Agents Targeting Breast Cancer Cells

We previously described the development of a DNA-alkylating compound that showed selective toxicity in breast cancer cells. This compound contained an estrogen receptor α (ERα)-binding ligand and a DNA-binding/methylating component that could selectively methylate the N3-position of adenines at adenine-thymine rich regions of DNA. Herein, we describe mechanistic investigations that demonstrate that this class of compounds facilitate the translocation of the ERα-compound complex to the nucleus and induce the expression of ERα target genes. We confirm that the compounds show selective toxicity in ERα-expressing cells, induce ERα localization in the nucleus, and verify the essential role of ERα in modulating the toxicity. Minor alterations in the compound structure significantly affects the DNA binding ability, which correlates to the DNA-methylating ability. These studies demonstrate the utility of DNA-alkylating compounds to accomplish targeted inhibition of the growth of specific cancer cells; an approach that may overcome shortcomings of currently used chemotherapy agents.

DNA repair pathways as guardians of the genome: Therapeutic potential and possible prognostic role in hematologic neoplasms

DNA repair pathways, which are also identified as guardians of the genome, protect cells from frequent damage that can lead to DNA breaks. The most deleterious types of damage are double-strand breaks (DSBs), which are repaired by homologous recombination (HR) and non-homologous end joining (NHEJ). Single strand breaks (SSBs) can be corrected through base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Failure to restore DNA lesions or inappropriately repaired DNA damage culminates in genomic instability and changes in the regulation of cellular functions. Intriguingly, particular mutations and translocations are accompanied by special types of leukemia. Besides, expression patterns of certain repair genes are altered in different hematologic malignancies. Moreover, analysis of mutations in key mediators of DNA damage repair (DDR) pathways, as well as investigation of their expression and function, may provide us with emerging biomarkers of response/resistance to treatment. Therefore, defective DDR pathways can offer a rational starting point for developing DNA repair-targeted drugs. In this review, we address genetic alterations and gene/protein expression changes, as well as provide an overview of DNA repair pathways.

Secondary clonal hematologic neoplasia following successful therapy for acute promyelocytic leukemia (APL): A report of two cases and review of the literature

Although rare, secondary clonal hematologic neoplasia may occur after successful therapy for acute promyelocytic leukemia (APL). These secondary clonal events may be considered therapy-related, but may also be due to an underlying background of clonal hematopoiesis from which both malignancies may develop. In this manuscript, we describe two patients with secondary clones after APL therapy characterized in one patient by deletion of chromosome 11q23 and, in the other, by monosomy of chromosome 7, and also provide a review of all secondary clonal disorders described after APL therapy. We suggest that since most reports identify karyotypic abnormalities not typically associated with chemotherapy, there may be another mechanism underlying secondary clonal development after complete response to initial APL therapy.

Clinical Features and Outcomes of 666 Cases with Therapy-Related Myelodysplastic Syndrome (t-MDS)

Therapy-related myelodysplastic syndrome (t-MDS) is a serious complication of chemoradiotherapy for primary diseases. This cohort was aimed to determine the clinical features and outcomes of t-MDS in comparison with de novo MDS. I retrieved data of 666 cases with t-MDS, and 29,703 cases with de novo MDS diagnosed between 2001 and 2012 from the database of U.S. National Cancer Institute. Survival curves were estimated, and Cox proportional hazards model was constructed. Compared with patients with de novo MDS, patients with t-MDS tended to be young (median age; 65 vs. 76 years, p < 0.001), and were more likely to be female-sex (51.4 vs. 44.7%, p = 0.001). Median overall survival (OS) and 5-year OS rate are significantly poorer in t-MDS than de novo MDS (17.2 months and 22% vs. 31 months and 32%, respectively, p < .001). In t-MDS cases, with a median follow-up of 16 months (range 1-143 months), 521 cases (78.2%) had died. Of which, 78 (15%) cases had died from acute myeloid leukemia, and 66 (12.7%) cases had died from solid cancers. Of the total 66 cases died from solid cancers; 19 cases (28.8%) died from cancer of lung/bronchus, 11 cases (16.7%) breast cancers, and 10 cases (15.2%) ovarian cancer. In a multivariate analysis adjusted for clinical features, calendar period and radiotherapy, the hazard of mortality was significantly low in de novo MDS compared with t-MDS (hazard ratio 0.59; p < .001). In conclusions, t-MDS is a distinct entity of MDS in terms of clinical characteristics and prognosis.

National Institutes of Health Hematopoietic Cell Transplantation Late Effects Initiative: The Subsequent Neoplasms Working Group Report

Subsequent neoplasms (SN) after hematopoietic cell transplantation (HCT) cause significant patient morbidity and mortality. Risks for specific SN types vary substantially, with particularly elevated risks for post-transplantation lymphoproliferative disorders, myelodysplastic syndrome/acute myeloid leukemia, and squamous cell malignancies. This document provides an overview of the current state of knowledge regarding SN after HCT and recommends priorities and approaches to overcome challenges and gaps in understanding. Numerous factors have been suggested to affect risk, including patient-related (eg, age), primary disease-related (eg, disease type, pre-HCT therapies), and HCT-related characteristics (eg, type and intensity of conditioning regimen, stem cell source, development of graft-versus-host disease). However, gaps in understanding remain for each of these risk factors, particularly for patients receiving HCT in the current era because of substantial advances in clinical transplantation practices. Additionally, the influence of nontransplantation-related risk factors (eg, germline genetic susceptibility, oncogenic viruses, lifestyle factors) is poorly understood. Clarification of the magnitude of SN risks and identification of etiologic factors will require large-scale, long-term, systematic follow-up of HCT survivors with detailed clinical data. Most investigations of the mechanisms of SN pathogenesis after HCT have focused on immune drivers. Expansion of our understanding in this area will require interdisciplinary laboratory collaborations utilizing measures of immune function and availability of archival tissue from SN diagnoses. Consensus-based recommendations for optimal preventive, screening, and therapeutic approaches have been developed for certain SN after HCT, whereas for other SN, general population guidelines are recommended. Further evidence is needed to specifically tailor preventive, screening, and therapeutic guidelines for SN after HCT, particularly for unique patient populations. Accomplishment of this broad research agenda will require increased investment in systematic data collection with engagement from patients, clinicians, and interdisciplinary scientists to reduce the burden of SN in the rapidly growing population of HCT survivors.

The JAK2V617F mutation in normal individuals takes place in differentiating cells

The JAK2V617F mutation that results in a hyper-activation of the JAK2 kinase in the erythropoietin pathway is a molecular marker for myeloproliferative neoplasms. Using allele-specific Real-Time PCR, we detected the mutation in the blood of 17.3% (17/98) of normal donors; the mutant allele burden was, however, very low (<0.01% compared to >1% in polycythemia vera). It was much higher in differentiated blood cells in the peripheral blood than in undifferentiated CD34⁺ cells. Erythropoietin-stimulated differentiation of normal CD34⁺ cells in liquid culture increased the mutation frequency by 3.34-fold. When progenitors from 9 normal donors were grown in erythropoietin-stimulated semi-solid cultures, the mutation was found in 8.69% of the colonies, but only in <3% of the JAK2 alleles in each positive colony, suggesting that the mutation occurred only in a few cells per colony. In mouse erythroleukemia cells carrying human JAK2 DNA, wild-type or JAK2V617F, the frequencies of mutations from JAK2 wild-type to JAK2V617F and vice versa increased following erythroid differentiation. These results suggest that the mutation occurs and accumulates during differentiation. We hypothesize that genetic stability, which relies on DNA repair, is efficient in normal hematopoietic stem cells but is downgraded in differentiating cells, rendering them susceptible to mutations, including JAK2V617F.

Glycoconjugated Site-Selective DNA-Methylating Agent Targeting Glucose Transporters on Glioma Cells

DNA-alkylating drugs continue to remain an important weapon in the arsenal against cancers. However, they typically suffer from several shortcomings because of the indiscriminate DNA damage that they cause and their inability to specifically target cancer cells. We have developed a strategy for overcoming the deficiencies in current DNA-alkylating chemotherapy drugs by designing a site-specific DNA-methylating agent that can target cancer cells because of its selective uptake via glucose transporters, which are overexpressed in most cancers. The design features of the molecule, its synthesis, its reactivity with DNA, and its toxicity in human glioblastoma cells are reported here. In this molecule, a glucosamine unit, which can facilitate uptake via glucose transporters, is conjugated to one end of a bispyrrole triamide unit, which is known to bind to the minor groove of DNA at A/T-rich regions. A methyl sulfonate moiety is tethered to the other end of the bispyrrole unit to serve as a DNA-methylating agent. This molecule produces exclusively N3-methyladenine adducts upon reaction with DNA and is an order of magnitude more toxic to treatment resistant human glioblastoma cells than streptozotocin is, a Food and Drug Administration-approved, glycoconjugated DNA-methylating drug. Cellular uptake studies using a fluorescent analogue of our molecule provide evidence of uptake via glucose transporters and localization within the nucleus of cells. These results demonstrate the feasibility of our strategy for developing more potent anticancer chemotherapeutics, while minimizing common side effects resulting from off-target damage.

Neuroblastoma survivors are at increased risk for second malignancies: A report from the International Neuroblastoma Risk Group Project

BACKGROUND

The incidence of second malignant neoplasm (SMN) within the first ten years of diagnosis in high-risk neuroblastoma patients treated with modern, intensive therapy is unknown. Further, the underlying germline genetics that contribute to SMN in these survivors are not known.

METHODS

The International Neuroblastoma Risk Group (INRG) database of patients diagnosed from 1990 to 2010 was analysed. SMN risk was accessed by cumulative incidence, standardised incidence ratios (SIRs) and absolute excess risk. A candidate gene-based association study evaluated genetic susceptibility to SMN in neuroblastoma survivors.

RESULTS

Of the 5987 patients in the INRG database with SMN data enrolled in a clinical trial, 43 (0.72%) developed a SMN. The 10-year cumulative incidence of SMN for high-risk patients was 1.8% (95% confidence interval [CI] 1.0-2.6%) compared with 0.38% (95% CI: 0.22-0.94%) for low-risk patients (P = 0.01). High-risk patients had an almost 18-fold higher incidence of SMN compared to age- and sex-matched controls (SIR = 17.5 (95% CI: 11.4-25.3), absolute excess risk = 27.6). For patients treated on high- and intermediate-risk clinical trials, the SIR of acute myelogenous leukaemia was 106.8 (95% CI: 28.7-273.4) and 127.7 (95%CI: 25.7-373.3), respectively. Variants implicating DNA repair genes XRCC3 (rs861539: P = 0.006; odds ratio: 2.04, 95%CI: 1.19-3.46) and MSH2 (rs17036651: P = 0.009; odds ratio: 0.26, 95% CI: 0.08-0.81) were associated with SMN.

CONCLUSION

The intensive multi-modality treatment strategy currently used to treat high-risk neuroblastoma is associated with a significantly increased risk of secondary acute myelogenous leukaemia. Defining the interactions of treatment exposures and genetic factors that promote the development of SMN is critical for optimising survivorship care.

Therapy-related myelodysplastic syndromes, or are they?

The incidence of therapy-related myelodysplastic syndromes (t-MDS) is increasing as the number of cancer survivors is increasing. While t-MDS is currently defined descriptively by prior receipt of chemotherapy and/or radiotherapy, some forms of MDS that occur post localized radiation monotherapy, biologically and clinically resemble de novo (d)-MDS more than t-MDS, and therefore may not be truly therapy-related. Although patients with t-MDS, as a group, fare worse than patients with d-MDS, a variation in individual outcomes of patients with t-MDS has increasingly been appreciated. As such, accurate risk stratification is important for counseling of patients and for clinical decision making. Most of the current clinical tools used for prognostication in t-MDS were developed for d-MDS and were not specifically validated in patients with t-MDS. The management of patients with t-MDS remains challenging, highlighting the importance of developing effective prevention strategies as well as newer, targeted, and rationally-designed therapeutic interventions.

Effect of therapy-related acute myeloid leukemia on the outcome of patients with acute myeloid leukemia

Therapy-related acute myeloid leukemia (t-AML) is a rare and almost always fatal late side effect of antineoplastic treatment involving chemotherapy, radiotherapy or the two combined. The present retrospective study intended to characterize t-AML patients that were diagnosed and treated in a single referral to an oncological institution in North Portugal. Over the past 10 years, 231 cases of AML were diagnosed and treated at the Portuguese Institute of Oncology of Porto, of which 38 t-AML cases were identified. Data regarding the patient demographics, primary diagnosis and treatment, age at onset of therapy-related myeloid neoplasm, latency time of the neoplasm, cytogenetic characteristics, AML therapy and outcome were collected from medical records. A previous diagnosis with solid tumors was present in 28 patients, and 10 patients possessed a history of hematological conditions, all a lymphoproliferative disorder. Breast cancer was the most frequent solid tumor identified (39.5% of all solid tumors diagnosed). The mean latency time was 3 years. In the present study, t-AML patients were older (P<0.001) and more frequently carried cytogenetic abnormalities (P=0.009) compared with de novo AML patients. The overall survival time was observed to be significantly poorer among individuals with t-AML (P<0.001). However, in younger patients (age, <50 years) there was no difference between the overall survival time of patients with t-AML and those with de novo AML (P=0.983). Additionally, patients with promyelocytic leukemia possess a good prognosis, even when AML occurs as a secondary event (P=0.98). To the best of our knowledge, the present study is the first to evaluate t-AML in Portugal and the results are consistent with the data published previously in other populations. The present study concludes that although t-AML demonstrates a poor prognosis, this is not observed among younger patients or promyelocytic leukemia patients.

TRIP11-PDGFRB fusion in a patient with a therapy-related myeloid neoplasm with t(5;14)(q33;q32) after treatment for acute promyelocytic leukemia

Background

Therapy-related myeloid neoplasm after treatment for acute promyelocytic leukemia (APL) is a relatively infrequent but severe complication. Most therapy-related myeloid neoplasms after treatment for APL are classified as therapy-related myelodysplastic syndrome or therapy-related acute myeloid leukemia. Translocation of 5q31-33, PDGFRB occur rarely in therapy-related myeloid neoplasm and there has been two identified PDGFRB partner genes located at 14q32, TRIP11 and KIAA1509.

Results

The TRIP11-PDGFRB fusion was identified in a patient with therapy-related myeloid neoplasm with t(5;14)(q33;q32) after treatment of APL using conventional cytogenetics, fluorescence in situ hybridization (FISH) and molecular methods. Cytogenetic analysis of the bone marrow aspirate revealed 46, XY, t(5;14)(q33;q32) in all 20 analyzed cells. No other cytogenetic abnormalities were observed. Break-apart FISH analysis demonstrated that rearrangement of PDGFRB at 5q33 was positive in 460 of 500 cells analyzed, while the PML-RARA rearrangement remained undetectable by RT-PCR. Sequencing of RT-PCR products revealed fusion between exon 16 of TRIP11 and exon 11 of PDGFRB. However, the KIAA1509-PDGFRB fusion was not detected by RT-PCR.

Conclusion

We firstly demonstrated that therapy-related myeloid neoplasm with TRIP11-PDGFRB fusion was identified after treatment of APL.

Genetic variation as a modifier of association between therapeutic exposure and subsequent malignant neoplasms in cancer survivors

Subsequent malignant neoplasms (SMNs) are associated with significant morbidity and are a major cause of premature mortality among cancer survivors. Several large studies have demonstrated a strong association between the radiation and/or chemotherapy used to treat primary cancer and the risk of developing SMNs. However, for any given therapeutic exposure, the risk of developing an SMN varies between individuals. Genomic variation can potentially modify the association between therapeutic exposures and SMN risk and may explain the observed interindividual variability. In this review, the author provides a brief overview of the current knowledge regarding the role of genomic variation in the development of therapy-related SMNs and discusses the methodological challenges in undertaking an endeavor to develop a deeper understanding of the molecular underpinnings of therapy-related SMNs, such as an appropriate study design, the identification of an adequately sized study population together with a reliable plan for collecting and maintaining high-quality DNA, clinical validation of the phenotype, and the selection of an appropriate approach or platform for genotyping. Understanding the factors that can modify the risk of treatment-related SMNs is critical to developing targeted intervention strategies and optimizing risk-based health care for cancer survivors.

Therapy-related myelodysplasia and acute myeloid leukemia

Therapy-related leukemia (myelodysplasia and acute myeloid leukemia-t-MDS/AML) is a well-known complication of conventional chemoradiotherapy used to treat a variety of primary malignancies including Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), acute lymphoblastic leukemia (ALL), sarcoma, and ovarian and testicular cancers. The median time to development of t-MDS/AML is 3-5 years, with the risk decreasing markedly after the first decade. t-MDS/AML is the major cause of non-relapse mortality after autologous hematopoietic cell transplantation (HCT) for HL or NHL. The magnitude of risk of t-MDS/AML is higher, and the latency is shorter after HCT, compared to conventional therapy. Two types of t-MDS/AML are recognized depending on the causative therapeutic exposure: an alkylating agent/radiation-related type and a topoisomerase II inhibitor-related type. Inter-individual variability in the risk for development of t-MDS/AML suggests a role for genetic variation in susceptibility to genotoxic exposures. Treatment of t-MDS/AML with conventional therapy is associated with a uniformly poor prognosis, with a median survival of 6 months. Because of the poor response to conventional chemotherapy, allogeneic HCT is recommended. Current research is focused on developing risk prediction and risk reduction strategies.

Influence of ethnicity and improved outcome of acute myeloid leukaemia: two decades of follow-up of Israeli patient cohort

Acute myeloid leukaemia is a disease with unfavourable prognosis. The significance of various prognostic parameters is not fully understood. We studied 293 patients to examine the influence of ethnicity and molecular markers. The median survival for all patients was correlated with age, white blood cell count and karyotype, and marginally with FLT3 internal tandem duplication. Arab patients were younger than Jewish patients; however, their survival was poorer albeit being treated with the same protocols and having more favourable cytogenetics. Survival rates improved over time but only for patients undergoing allogeneic bone marrow transplantation (alloBMT). We conclude that in our young patient cohort, recent improvement in survival is attributed to alloBMT therapy and that ethnicity affected treatment outcome.

High frequency of NAD(P)H:quinone oxidoreductase 1 (NQO1) C(609)T germline polymorphism in MDS/AML with trisomy 8

The NQO1 C(609)T germline polymorphism resulting in a lowering of enzyme activity may confer susceptibility to MDS. To assess this association, we performed a case-control study including 330 Greek patients with de novo MDS and 416 healthy donors, using a Real-Time PCR genotyping method. Focusing on cytogenetic aberrations most commonly found in MDS, we retrospectively genotyped 566 MDS/AML patients carrying -5/del(5q), -7/del(7q), +8, del(20q) and -Y. The case-control analysis revealed no differences in NQO1 genotype distribution. Interestingly, a 6-fold increased frequency of the homozygous variant genotype was observed among patients with isolated trisomy 8 (p<0.0001), suggesting that null NQO1 activity may influence the occurrence of +8 in MDS/AML.

Frameshift-derived neoantigens constitute immunotherapeutic targets for patients with microsatellite-instable haematological malignancies: frameshift peptides for treating MSI+ blood cancers

PURPOSE

Microsatellite instability (MSI) resulting from loss of functional DNA mismatch repair was recently found in various haematological disorders. In coding sequences, MSI leads to frameshift mutations (FSMs) and the production of C-terminally altered proteins which are foreign to the immune system. Here, we wondered whether these frame-shifted peptide (FSP) sequences represent tumour-specific antigens also for MSI(+) leukaemia and lymphomas (L/L).

MATERIAL AND METHODS

A total of 33 coding region microsatellites were examined in MSI(+) L/L cell lines for the presence of FSMs. Thereafter, recognition of MSI(+) cells by established FSP-specific CD8(+) T cell lines was quantified using interferon (IFN)-γ enzyme-linked immunospot (ELISpot) assays. In each experiment, MSI(+) L/L cell lines and T2 targets exogenously loaded with the cognate peptide (=internal control) were employed. Supplementary, lytic activity towards tumour cells was analysed by standard chromium release assay ((51)Cr).

RESULTS

Mutational profiling of 33 coding microsatellite loci in nine MSI(+) L/L cell lines revealed instability in at least nine microsatellites. In each cell line, a distinct mutational profile was observed. Only three of the 33 loci were stable. FSP-specific and human leukocyte antigen-A2 (HLA-A2)-restricted T cells specifically recognised MSI(+) L/L cells endogenously expressing TGFβRII(-1), Caspase 5 (-1) and MSH3 (-1) in ELISpot assays. Moreover, specific killing of Caspase 5 (-1) and MSH3 (-1) expressing L/L cell lines was achieved in functional cytotoxicity assays.

CONCLUSION

Data presented here expand the importance of FSPs as shared and general tumour-specific antigens. Consequently, they open new avenues for specific immunotherapies not only for solid but also for MSI(+) haematological malignancies.

Therapy-related myeloid neoplasms in 39 Korean patients: a single institution experience

Background

Therapy-related myeloid neoplasms (t-MN) occur as late complications of cytotoxic therapy. This study reviewed clinical and cytogenetic characteristics of patients with t-MN at a single institution in Korea.

Methods

The study subjects included 39 consecutive patients diagnosed with t-MN. Each subject's clinical history of previous diseases, treatments, and laboratory data was reviewed, including cytogenetics. The primary diagnosis was hematologic malignancy in 14 patients and solid tumor in 25 patients.

Results

Therapy-related acute myeloid leukemia (t-AML, 66.7%) was found to be more common than therapy-related myelodysplastic syndrome (t-MDS). Primary hematologic malignancies that were commonly implicated included mature B-cell neoplasm and acute leukemia. Breast cancer was the most common primary solid tumor. The mean time interval from cytotoxic therapy initiation to t-MN detection was 49 months. Chromosomal aberrations were observed in 35 patients, and loss of chromosome 5, 7, or both accounted for 41% of all cases. Balanced rearrangements occurred in 13 patients; these patients showed shorter latency intervals (mean, 38 months) than patients with loss of chromosome 5 or 7 (mean, 61 months).

Conclusions

In this study, we determined the clinical and cytogenetic characteristics of Korean patients with t-MN. Although our results were generally consistent with those of previous reports, we found that t-MN resulting from de novo leukemia was common and that t-AML was more common than t-MDS at presentation. Multi-institutional studies involving a larger number of patients and additional parameters are required to investigate the epidemiology, genetic predisposition, and survival rate of t-MN in Korea.

Second malignant neoplasms: assessment and strategies for risk reduction

Improvements in early detection, supportive care, and treatment have resulted in an increasing number of cancer survivors, with a current 5-year relative survival rate for all cancers combined of approximately 66.1%. For some patients, these survival advances have been offset by the long-term late effects of cancer and its treatment, with second malignant neoplasms (SMNs) comprising one of the most potentially life-threatening sequelae. The number of patients with SMNs is growing, with new SMNs now representing about one in six of all cancers reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program. SMNs reflect not only the late effects of therapy but also the influence of shared etiologic factors (in particular, tobacco and excessive alcohol intake), genetic susceptibility, environmental exposures, host effects, and combinations of factors, including gene-environment interactions. For selected SMNs, risk is also modified by age at exposure and attained age. SMNs can be categorized into three major groups according to the predominant etiologic factor(s): (1) treatment-related, (2) syndromic, and (3) those due to shared etiologic exposures, although the nonexclusivity of these groups should be underscored. Here we provide an overview of SMNs in survivors of adult-onset cancer, summarizing the current, albeit limited, clinical evidence with regard to screening and prevention, with a focus on the provision of guidance for health care providers. The growing number of patients with second (and higher-order) cancers mandates that we also further probe etiologic influences and genetic variants that heighten risk, and that we better define high-risk groups for targeted preventive and interventional clinical strategies.

Molecular characterisation of murine acute myeloid leukaemia induced by 56Fe ion and 137Cs gamma ray irradiation

Exposure to sparsely ionising gamma- or X-ray irradiation is known to increase the risk of leukaemia in humans. However, heavy ion radiotherapy and extended space exploration will expose humans to densely ionising high linear energy transfer (LET) radiation for which there is currently no understanding of leukaemia risk. Murine models have implicated chromosomal deletion that includes the hematopoietic transcription factor gene, PU.1 (Sfpi1), and point mutation of the second PU.1 allele as the primary cause of low-LET radiation-induced murine acute myeloid leukaemia (rAML). Using array comparative genomic hybridisation, fluorescence in situ hybridisation and high resolution melt analysis, we have confirmed that biallelic PU.1 mutations are common in low-LET rAML, occurring in 88% of samples. Biallelic PU.1 mutations were also detected in the majority of high-LET rAML samples. Microsatellite instability was identified in 42% of all rAML samples, and 89% of samples carried increased microsatellite mutant frequencies at the single-cell level, indicative of ongoing instability. Instability was also observed cytogenetically as a 2-fold increase in chromatid-type aberrations. These data highlight the similarities in molecular characteristics of high-LET and low-LET rAML and confirm the presence of ongoing chromosomal and microsatellite instability in murine rAML.

Prognostic factors for therapy-related acute myeloid leukaemia (t-AML)--a single centre experience

Prognostic parameters for treatment outcome in 42 consecutive patients with t-AML diagnosed and treated in a single centre between 2000-2010 (mean age: 56.07 years, range: 23-84; 30 females) were evaluated retrospectively/prospectively. Antecedent malignancy occurred in 37 patients (88.15%): 28 solid cancers (breast, n=14), nine haematological. History of previous chemotherapy (CT), radiotherapy (RT) alone and combined CT/RT was present in 42.9%, 6.19% and 30.1% patients, respectively. Primary disease was active in 11 patients (six relapsed or metastatic cancers; five autoimmune diseases). Myelodysplastic syndrome preceded t-AML in 29% of patients. Median latency period from prior CT/RT was 54.62 months (range: 6-243). Median WBC count was 27.23 × 10⁹/L, platelet count 62.29 × 10⁹/L, haemoglobin level 87.83 g/L, peripheral blood and bone marrow blast percentage 30.7% and 66.7% respectively, serum LDH 1216 U/L. Aberrant expression of B or T lymphoid markers was registered in seven out of 39 and six out of 39 patients, respectively. Aberrant karyotype was detected in 24 out of 33 (72.7%) of eligible patients: favourable: 15.2%, intermediate: 42.4% and unfavourable: 42.4%. Eastern Cooperative Oncology Group (ECOG) performance status greater or equal to 2 and Haematopoietic Cell Transplantation Specific Comorbidity Index (HCT-CI) greater or equal to 3 exhibited 83.3% and 76.2% patients, respectively. Intensive induction CT for t-AML was administered in 24 patients. The median follow-up and the median overall survival (OS) for the whole cohort were 2 months and 5.94 months (range: 0.5-34), respectively. In 10 patients (23.8%) achieving complete remission (CR), median disease free survival (DFS) was 11.8 months (range: 4-32). Only CD19 expression, pretreatment karyotype, ECOG PS, HCT-CI and activity of primary disease had impact on OS (P<0.05).

Role of genetic susceptibility in development of treatment-related adverse outcomes in cancer survivors

Clear and unambiguous associations have been established between therapeutic exposures and specific complications. However, considerable interindividual variability is observed in the risk of developing an outcome for a given therapeutic exposure. Genetic predisposition and especially its interaction with therapeutic exposures can potentially exacerbate the toxic effect of treatment on normal tissues and organ systems, and can possibly explain the interindividual variability. This article provides a brief overview of the current knowledge about the role of genomic variation in the development of therapy-related complications. Relatively common outcomes with strong associations with therapeutic exposures, including cardiomyopathy, obesity, osteonecrosis, ototoxicity, and subsequent malignancies are discussed here. To develop a deeper understanding of the molecular underpinnings of therapy-related complications, comprehensive and near-complete collection of clinically annotated samples is critical. Methodologic issues such as study design, definition of the endpoints or phenotypes, identification of appropriate and adequately sized study population together with a reliable plan for collecting and maintaining high-quality DNA, and selection of an appropriate approach or platform for genotyping are also discussed. Understanding the etiopathogenetic pathways that lead to the morbidity is critical to developing targeted prevention and intervention strategies, optimizing risk-based health care of cancer survivors, thus minimizing chronic morbidities and improving quality of life.

Second malignancies among elderly survivors of cancer

The U.S. population is aging, life expectancy is increasing, and cancer is a disease associated with aging. Advances in screening and therapeutics have led to a growing number of cancer survivors who are at risk for the development of secondary malignancies. Although the risks for the development of second malignancies following a first diagnosis of cancer are well described for survivors of childhood malignancies, there are fewer data for malignancies common in older adults. With the aging of the U.S. population, and with improving survival statistics in many adult malignancies, there is an increasing need to identify those second malignancies that might develop in the older adult survivor of cancer. In this paper, we describe the types and rates of second malignancies following cancers commonly seen in older adults and review the literature on these malignancies. Comparisons are made between older and younger adults with regard to the risks for developing treatment-related cancers with different modalities. Recommendations for early detection of second malignancies are summarized, though there remains an unmet need for evidence-based guidelines for screening for second malignancies in the older adult in particular.

DNA site-specific N3-adenine methylation targeted to estrogen receptor-positive cells

A compound that can target cells expressing the estrogen receptor (ER), and produce predominantly 3-MeA adducts in those cells has been designed and synthesized. This compound produces mainly the 3-MeA adduct upon reaction with calf thymus DNA, and binds to the ER with a relative binding affinity of 51% (estradiol = 100%). The compound is toxic to ER-expressing MCF-7 breast cancer cells, and pre-treatment with the ER antagonist fulvestrant abrogates the toxicity. Pre-treatment of MCF-7 cells with netropsin, which inhibits N3-adenine methylation by the compound, resulted in a threefold decrease in the toxicity. These results demonstrate the feasibility of this strategy for producing 3-MeA adducts in targeted cells.

Therapy-related myeloid leukemia after treatment for epithelial ovarian carcinoma: an epidemiological analysis

OBJECTIVE

Therapy related acute myeloid leukemia (t-AML) is a potential late complication of cytotoxic therapy, and it is of particular concern in the treatment of patients with epithelial ovarian carcinoma (EOC) exposed to multiple courses of chemotherapy during the course of their disease. This study examines the incidence, characteristics and clinical outcomes of patients who developed secondary myeloid-type leukemia after a diagnosis of EOC.

METHODS

National Cancer Institute's Surveillance, Epidemiology and End Results database was pooled for diagnosis of secondary myeloid leukemia after an initial diagnosis of EOC. This group of patients was compared to patients with de novo AML, and to EOC patients who did not develop secondary myeloid leukemia. Demographic, cytopathological and survival data were recorded. Cox Proportional Hazards model was used to calculate hazard ratios (HR) for developing secondary leukemia and to determine the statistically significant variables impacting survival. Kaplan-Meier estimates of survival were obtained and comparisons between the groups were performed using log-rank test.

RESULTS

One hundred and nine myeloid leukemia cases were identified among 63,359 patients with a prior diagnosis of EOC for an overall incidence of 0.17%. The median latency to development of leukemia was 4 years (range 0-27 years). Median survival from the time of secondary leukemia diagnosis was 3 months and significantly worse than the 6 month median survival in patients with de novo AML (p<0.001). Age at leukemia diagnosis greater than 65 and development of secondary vs. de novo leukemia had a statistically worse prognosis on multivariate analysis (HR of 2.69, 95%CI 2.60-2.78 and 1.81, 95%CI 1.49-2.20 respectively). The development of secondary leukemia was more common with EOC diagnosis made prior to the platinum/taxane era (HR 6.70, 95%CI 3.69-12.18). There was no difference in median survival between EOC patients who developed AML and those who did not.

CONCLUSION

Development of t-AML is a rare but lethal event among EOC patients, and its incidence has decreased significantly since the use of platinum/taxane-based chemotherapy became the standard of care.

Therapy-related myeloid neoplasms: pathobiology and clinical characteristics

Therapy-related myeloid neoplasms (t-MNs) are serious long-term consequences of cytotoxic treatments for an antecedent disorder. t-MNs are observed after ionizing radiation as well as conventional chemotherapy including alkylating agents, topoisomerase-II-inhibitors and antimetabolites. In addition, adjuvant use of recombinant human granulocyte-colony stimulating factor may also increase the risk of t-MNs. There is clinical and biological overlap between t-MNs and high-risk de novo myelodysplastic syndromes and acute myeloid leukaemia suggesting similar mechanisms of leukaemogenesis. Human studies and animal models point to a prominent role of genetic susceptibilty in the pathogenesis of t-MNs. Common genetic variants have been identified that modulate t-MN risk, and t-MNs have been observed in some cancer predisposition syndromes. In either case, establishing a leukaemic phenotype requires acquisition of somatic mutations - most likely induced by the cytotoxic treatment. Knowledge of the specific nature of the initiating exposure has allowed the identification of crucial pathogenetic mechanisms and for these to be modelled in vitro and in vivo. Prognosis of patients with t-MNs is dismal and at present, the only curative approach for the majority of these individuals is haematopoietic stem cell transplantation, which is characterized by high transplant-related mortality rates. Novel transplantation strategies using reduced intensity conditioning regimens as well as novel drugs - demethylating agents and targeted therapies - await clinical testing and may improve outcome. Ultimately, individual assessment of genetic risk factors may translate into tailored therapies and establish a strategy for reducing t-MN incidences without jeopardizing therapeutic success rates for the primary disorders.

Temozolomide-induced myelodysplasia

A patient who had received temozolomide (TMZ) as a single agent in treatment of malignant glioma developed therapy-induced myelodysplasia (T-MDS). TMZ is an orally active imidazotetrazine which methylates guanine residues in DNA, ultimately causing single and double-strand DNA breaks leading to apoptotic cell death. TMZ does not chemically cross-link DNA and is considered a nonclassical alkylating agent, similar in structure and activity to dacarbazine. Observations on this patient, and on similarly treated others, suggest that the cumulative dose threshold (CDT) for TMZ that predisposes to T-MDS and which may potentially lead to acute myeloid leukemia (T-AML) is around 18000 to 20000 mg/sq m. Although the incidence of T-MDS and the predisposing CDT of TMZ may differ from that of other potentially leukemogenic compounds currently and formerly used as chemotherapeutic agents, all alkylating agents, including TMZ, should be considered potentially leukemogenic when administered long term.

A case report of the second de novo acute myeloid leukemia (AML) following allogeneic stem cell transplantation in a patient with the first AML

Secondary leukemia occurring after hematopoietic stem cell transplantation (HSCT) for acute myeloid leukemia (AML) is rare. Secondary AML usually follows autologous and not allogeneic transplants. When a new leukemia develops in a patient successfully treated with an allogeneic HSCT, the possibility of a de novo or secondary leukemia from either the donor or recipient should be considered. We present a case initially diagnosed as de novo AML without a cytogenetic abnormality. The patient was successfully treated with an HLA-matched sibling allogeneic HSCT. However, more than six years later, AML developed again and was associated with new complex cytogenetic abnormalities. After a second HSCT, the patient has been followed without serious complications. Considering the allogeneic setting, the newly developed cytogenetic abnormalities, a relatively long latent period, and the good clinical course after the second allogeneic HSCT, this case might represent a second de novo AML following successful treatment of the first AML.

Incidence and susceptibility to therapy-related myeloid neoplasms

Therapy-related myeloid neoplasms (t-MN) include acute myeloid leukemias and myelodysplastic syndromes arising in patients who have been treated with chemotherapy, radiation therapy, immunosuppressive agents or after documented exposure to environmental carcinogen. t-MN are defined according to the primary treatment and the corresponding genetic and molecular lesions. Chromosome(s) 7 and/or 5 monosomies or deletions are typical of alkylating agent-induced AML, while balanced translocations involving chromosome bands 11q23 and 21q22 are associated to preceeding therapy with DNA-topoisomerase II inhibitors. Antimetabolites, and in particular the immunosuppressive agents azathioprine and fludarabine, have also been recently associated to t-MN. Leukemias developing after benzene exposure are similar to t-MN and are characterized by chromosomal aberrations, which have been also observed among otherwise healthy benzene-exposed workers. Individual predisposing factors, including polymorphisms of detoxification and DNA-repair enzymes have been identified. Two genetic variants in key metabolizing enzymes, myeloperoxidase and NAD(P)H:quinone oxidoreductase, have been shown to influence susceptibility to benzene hematotoxicity. Combination of polymorphisms impairing detoxification and DNA repair may significantly increase therapy-related myeloid neoplasm risk. Among hematological malignancies, long-term survivors of Hodgkin's lymphoma are exposed to an increased t-MN risk, particularly when receiving MOPP-based and escalated-BEACOPP regimens, and when alkylators are combined to radiotherapy. Patients with lymphoma are at highest risk if total body irradiation followed by autologous stem cell transplantation is used as rescue or consolidation. The addition of granulocyte-colony stimulating factor (G-CSF) and radiotherapy plays a significant role in t-MN following treatment of childhood acute lymphoblastic leukemia. In solid tumors, treatment for breast cancer and germ-cell tumors has been associated with a 1-5% lifetime risk of t-MN.

Therapy-related myeloid neoplasms

Session 5 of 2007 Workshop of the Society for Hematopathology/European Association for Haematopathology focused on therapy-related myeloid neoplasms. This report discusses the diversity and relevance of clinical, pathologic, and genetic features and provides an update on the pathogenesis of these disorders. We highlight common diagnostic issues such as the differentiation between therapy-related myelodysplastic syndrome and therapy-related acute erythroid leukemia. As similar therapeutic interventions are frequently considered for patients with either of these diagnoses, in the current World Health Organization classification, regardless of morphologic presentation, therapy-related myeloid neoplasms are considered together as a unique clinicopathologic syndrome of therapy-related myelodysplastic syndrome/acute myeloid leukemia. Nevertheless, recognition of the diverse morphologic features is crucial as bone marrow morphologic examination remains the first and important step of patient evaluation. We also present examples of therapy-related acute myeloid leukemias with recurrent cytogenetic abnormalities. In these cases, the precise classification is clinically important because it is associated with distinct clinical outcome.

Therapy-related acute myeloid leukemia with t(8;21) (q22;q22) shares many features with de novo acute myeloid leukemia with t(8;21)(q22;q22) but does not have a favorable outcome

To determine if therapy-related acute myeloid leukemia (t-AML) with t(8;21)(q22;q22) [t-AML-t(8;21)] harbors similar characteristic clinicopathologic features as de novo AML-t(8;21) (q22;q22), we studied 13 cases of t-AML-t(8;21) and 38 adult cases of de novo AML-t(8;21) diagnosed and treated at our hospital (1995-2008). Of 13 t-AML-t(8;21) cases, 11 had previously received chemotherapy with or without radiation for malignant neoplasms and 2 received radiation alone. The median latency to t-AML onset was 37 months (range, 11-126 months). Compared with patients with de novo AML-t(8;21), patients with t-AML-t(8;21) were older (P = .001) and had a lower WBC count (P = .039), substantial morphologic dysplasia, and comparable CD19/CD56 expression. The AML1-ETO (RUNX1-RUNX1T1) fusion was demonstrated in all 10 cases assessed. Class I mutations analyzed included FLT3 (0/10 [0%]), RAS (0/10 [0%]), JAK2 V617 (0/11 [0%]), and KIT (4/11 [36%]). With a median follow-up of 13 months, 10 patients with t-AML-t(8;21) died; the overall survival was significantly inferior to that of patients with de novo AML-t(8;21) (19 months vs not reached; P = .002). These findings suggest that t-AML-t(8;21) shares many features with de novo AML-t(8;21)(q22;q22), but affected patients have a worse outcome.

Expression patterns of CD33 and CD15 predict outcome in patients with acute myeloid leukemia

Expression patterns of CD33 and CD15 in normal/reactive bone marrow (n = 13) and in leukemic blasts from patients with acute myeloid leukemia (n = 129) were determined using multiparameter flow cytometry and a standard panel of triple antibody combinations. Five patterns, corresponding to the consecutive stages of myeloid differentiation, were identified [I: CD33-/CD15- (n = 18), II: CD33+/CD15- (n = 43), III: CD33+/CD15 heterogeneous (n = 10), IV: CD33+/CD15+ (n = 50), V: CD33-/CD15+ (n = 8)]. Patients with pattern II had the highest relapse rate and shortest median overall survival (OS, 8 months), but they were also the oldest (median age 72 years) and had the highest frequency of unfavorable cytogenetic aberrations. Pattern V patients had a short OS (median 14 months) even though they were the youngest (median age 50 years), had high remission rate and did not have unfavorable cytogenetics. In multivariate analysis, age, cytogenetics, CD15 expression and the presented immunophenotypic classification were significant for OS (age p = 0.004, cytogenetics p = 0.011, immunophenotype pattern p = 0.024, CD15 p = 0.031). Age (p = 0.001) and immunophenotypic classifications (p = 0.015) were significant for disease-free survival in patients who achieved complete remission.

Malignant epithelial tumors and hematologic malignancy

The aim of this study was to analyze the value of cytology in differentiation between malignant epithelial tumor metastases and hematologic malignancy. The follow-up of ten (10) patients who underwent diagnosis and treatment of two malignant diseases, i.e. carcinoma and hematologic malignancy, was performed in the 2000-2005 period. The median of age of our patients was 72 years (range: 49-79). Cytological examination included epithelial tumors, lymph nodes and bone marrow standard Pappenheim and immunocytochemically stained smears. Carcinoma was initially diagnosed in 40% (4/10) patients and hematologic malignancy in 50% (5/10) patients, while both diseases co-occurred in one patient (1/10). Most of hematologic malignancy cases (4/10) were diagnosed as lymphoma. Multiple myeloma was diagnosed in 3 out of 10 patients (30%). Individual cases of acute myeloblastic leukemia, chronic lymphocytic leukemia, and chronic myeloid leukemia were diagnosed in the remaining three patients. Most carcinomas were breast cancer (8/10), while prostate and thyroid gland cancer were diagnosed each in one patient, respectively.

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.

Therapy-related acute myelogenous leukemia and myelodysplastic syndrome

Therapy-related acute myelogenous leukemia and myelodysplastic syndrome (t-AML/MDS) are increasing in prevalence with aging of the population and improved survival of patients treated with chemotherapy or radiotherapy for other malignancies. Research focused on the pathogenesis of t-AML/MDS will provide insight into the pathogenesis of de novo AML/MDS. Participation in clinical trials should be encouraged for this patient population because results with available treatment options are clearly suboptimal.

MDR1 and CYP3A4 polymorphisms are associated with HIV seropositivity in Israeli patients but do not influence the course of HIV disease

Recent studies have examined the relationship between polymorphic alleles of the MDR1 gene and the course of HIV. Such polymorphisms may alter the metabolism of antiretroviral medications or influence susceptibility to HIV infectivity. We therefore studied a polymorphism in MDR1 (C3435T), and the CYP3A4*1B variant allele, the latter of which has not been previously studied in HIV. Ninety-six patients of either Ethiopian (57) or Caucasian (39) ethnicity and 276 controls were studied including serial CD4 counts, clinical course, and AIDS-defining illnesses. For both ethnic groups, the C allele of MDR1 C3435T was highly associated with being infected with HIV (p < 0.0001) compared to controls, but genotype did not influence change in CD4 counts over time in the patients, whether or not they were treated with antiretrovirals. CYP3A4*1B was also significantly associated with being infected with HIV (p < 0.0001) both in heterozygotes and in homozygotes for the polymorphism, but only for Ethiopians (p < 0.023 compared to Caucasians, p = 0.44). CYP3A4*1B did not influence CD4 count or AIDS defining illnesses. We conclude that in Israeli patients, polymorphisms in drug metabolism and disposition genes may influence infectivity of HIV but do not influence the course of the disease. Larger studies are needed to confirm these findings.