Therapy-related Myeloid Leukemia Research Articles

FLT3 Mutated Acute Myeloid Leukemia after CD19 CAR-t Cells.

Chimeric Antigen Receptor T-cells have improved the life expectancy of severely pretreated patients with aggressive hematological cancers; for this reason, therapy-related myeloid leukemias are becoming of great concern in this field, despite their clonal phylogenesis and mutational landscape have not been fully explored yet. This case discusses a 33-year-old man with refractory large B-cell lymphoma, treated with Chimeric Antigen Receptor T-cell (CAR-T) therapy as the 7th line of treatment. Despite a persistent partial response, the patient developed therapy-related acute myeloid leukemia (t-AML) six months post-CAR-T, revealing pre-existing clonal hematopoiesis. The myeloid malignancy exhibited an unusual hypocellular/dysplastic pattern, progressing to an established blast phase with cytopenia. Treatment with demethylating agents and BCL2 inhibitors proved ineffective, leading to t-AML with hyperleukocytosis and FLT3-ITD gain, resulting in the patient's death. This case underscores the impact of severe pretreatment and bone marrow impairment in CAR-T-associated t-AML, emphasizing their role over insertional mutagenesis. Furthermore, it highlights the retention of classic therapy-related leukemia characteristics, including the potential for acquiring FLT3 mutations and displaying dysplastic morphology in these secondary leukemias.

Therapy-related myeloid leukemia following Pleuropulmonary blastoma: A case report

The development of secondary malignancy (SM) is the most worrisome long-term complication of childhood cancer. Acute myeloid leukemia is the most prevalent neoplasm that occurs after treatment with alkylating agents and topoisomerase II inhibitors. Pleuropulmonary blastoma (PPB) is a rare lung neoplasm in children. Type II and type III of this cancer are markedly aggressive and have a recurrent nature. Chemotherapy, radiation therapy, and hematopoietic stem cell transplant (HSCT) are treatment modalities that make these patients prone to secondary malignancy. Here was presented and discussed a case of myeloid leukemia 3.5 years after treatment of Pleuropulmonary blastoma in a 5.5-year-old boy who was a candidate for high dose chemotherapy and autologous stem cells transplant (auto-SCT) because of frequent recurrence and lack of response to chemotherapy and radiation therapy. It seems this is the first reported case of therapy-related myeloid leukemia (t-AML) after PPB in children. Awareness of the creation of this complication following administration of cytotoxic therapies in the treatment of solid tumors will increase physician attention in the selection of treatment modality as well as the counseling of patients at the time of diagnosis.

Chronic Myeloid Leukemia Following Exposure to Radioactive Iodine (I 131): A Systematic Review

IntroductionTherapy-related leukemia or secondary leukemia are the terms that describe the occurrence of leukemias following exposure to hematotoxins and radiation to emphasize the difference from leukemia that arises de novo . Many leukemogenic agents have been described, including radiation, alkylating agents, among others . Certain host factors contribute to this predisposition, such as polymorphisms in drug-metabolizing enzymes and inherited cancer predisposition syndrome . These rising leukemias have no specific biologic features that set them apart from de novo malignancies .Therapy-related acute myeloid leukemia (t-AML) has extensive literature to support it. In contrast, therapy-related chronic myeloid leukemia (t-CML) possibly because it originates from a more potent premature progenitor cell .Radioactive iodine (RAI) with I 131 has an established role in managing differentiated thyroid carcinoma, namely papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma. However, concerns have been raised about its possible carcinogenic effects. Papers of t-CML following I 131 are increasingly reported, and thus this review is dedicated to highlighting it.Designs and methodsAll reports from the 1960s to date related to CML following RAI therapy were searched on Google Scholar and PubMed. Different search terms with Boolean function to search for the relevant articles. All articles were in English.ResultsWe identified ten articles reporting 12 cases, as presented in table 1. We found that most of the reports were for men (8/12) under the age of 60 years (10/12), and the primary tumor was of PTC characteristics (5/12 were PTC, and 3/12 were mixed papillary-follicular carcinoma). The dose of I 131 ranged between 30 millicuries (mCi) to 850 mCi; the mean dose was 331 mCi. Also, t-CML developed within the first ten years (9/12), mainly between 4-7 years post-exposure.DiscussionA few reports found a statistically significant increased risk of leukemia following RAI therapy; some suggested a relative risk of 2.5 for I 131 vs. no I 131 . Observed findings from these studies include a linear relationship between the cumulative dose of I 131 and the risk of leukemia, doses higher than 100 mCi were associated with a greater risk of developing secondary leukemia, and most of the leukemias developed within the initial ten years of exposure .The precise mechanism through which RAI provokes leukemia is largely unclear. Possibly, by inducing oxidative stress, reactive oxygen species production results in damage to the cellular membrane, DNA strand breakage, DNA base alterations, and eventually cancer in the instances of poor repair of damage .Many questions remain open. For example, most of the subjects had PTC histopathology in our review. Is there a relationship between PTC and the emergence of leukemia? This question is relevant because some reported that PTC has a mutation of the RET protooncogene, which has been linked to leukemia, prostate and breast cancers.ConclusionAlthough the risk of t-CML appears to be low based on current reports, it should not be disregarded. Further studies are needed to establish or refute a causal relationship. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Characteristics and Outcomes of Therapy-Related Versus De Novo Acute Myeloid Leukemia with Normal Karyotype

Characteristics and Outcomes of Therapy-Related Versus De Novo Acute Myeloid Leukemia with Normal Karyotype

Abstract 1233: Myeloperoxidase (MPO) activity in myeloid-derived suppressor cells (MDSCs): effects on anticancer drug activity

Abstract In cancer, suppression of host immunity is related, in part, to immature myeloid-derived suppressor cells (MDSCs) expanded in response to various tumor- or stroma-derived factors. Here, the expression and activity of myeloperoxidase (MPO) was examined in both granulocytic (PMN) and monocytic (M) MDSC subsets recovered from the spleens of 4T1 tumor-bearing mice, as well as interferon regulatory factor-8 (IRF8) knockout mice (IRF8-/-) which develop high levels of MDSCs due to IRF8-deficiency. Phenotypically identical cells from non-tumor-bearing mice served as controls. In addition, the role of MPO in PMN-MDSCs as a determinant of DNA damage induced by the anticancer agents etoposide (VP-16), camptothecin (CPT) and parthenolide (PTL), was evaluated for potential immunomodulatory effects. MPO protein content was ~4-fold greater in PMN-MDSCs from tumor-bearing compared to non-tumor-bearing mice, while MPO specific activity was equivalent in these two populations. MPO protein content in PMN-MDSCs from IRF8-/- mice was at least comparable to levels found in tumor-bearing hosts. In both IRF8-/- and tumor-bearing mice, PMN-MDSCs contained 5-10-fold greater MPO protein and overall enzyme activity compared to isolated M-MDSCs. VP-16 (5 µM)- and PTL (100 µM)-induced DNA strand breaks were 4-fold greater in PMN- compared to M-MDSCs from tumor-bearing mice. In addition, the heme-synthesis inhibitor, succinylacetone (SA) reduced MPO activity 2-3-fold in PMN-MDSCs from tumor-bearing mice with a corresponding decrease in drug-induced DNA damage for both VP-16 and PTL with no effect on CPT-induced DNA damage. The antioxidant dehydroascorbate decreased VP-16-induced DNA damage in PMN-MDSCs containing MPO activity, but not in those cells pre-incubated with SA to deplete MPO. These results indicate that MPO-dependent activation of VP-16 and PTL enhance DNA damage. Antioxidant protection against VP-16-induced DNA damage is consistent with MPO-mediated oxidative activation of VP-16 to a redox-cycling phenoxyl radical (Mol. Pharmacol. 79: 479-487, 2011). Overall, these results suggest that: 1) PTL may be useful to eliminate PMN-MDSCs; 2) MPO activation of VP-16 in PMN-MDSCs may be deleterious via oxidative DNA damage resulting in mixed-lineage leukemia (MLL) gene rearrangements known to be causal for therapy-related myeloid leukemias. Support: CA172105; CA090787; CA140622 Citation Format: Jack C. Yalowich, Ragu Kanagasabai, Colleen S. Netherby, Michelle N. Messmer, Scott I. Abrams. Myeloperoxidase (MPO) activity in myeloid-derived suppressor cells (MDSCs): effects on anticancer drug activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1233.

Chronic Myeloid Leukemia Following Treatment for Primary Neoplasms or Other Medical Conditions.

Therapy-related chronic myeloid leukemia (CML) has been reported, but its clinical presentation and pathologic features have not yet been well characterized. Twenty-one cases of CML following treatment for primary diseases were collected and retrospectively analyzed. The clinical presentation, pathologic features, and cytogenetic profile were similar to de novo CML. In particular, those with an isolated Philadelphia chromosome constituted 88.9% of our cases, and additional aberrations characteristic of therapy-related acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) were not identified in this study. The patients responded to imatinib/derivatives and survived with limited follow-up. Therapy-related CML has a clinical presentation, pathologic features, and cytogenetic profile akin to de novo CML. Absence of additional significant aberrations seems to suggest a pathogenesis different from therapy-related AML/MDS. Therapy-related CML exhibits a robust therapeutic response to imatinib/derivatives and favorable clinical outcomes similar to de novo CML.

Incidences and outcomes of therapy-related chronic myeloid leukemia in the era of tyrosine kinase inhibitors: Surveillance of the CML Cooperative Study Group

This study was performed to investigate the features and outcome of patients with therapy-related chronic myeloid leukemia (TR-CML) who were treated with tyrosine kinase inhibitors (TKIs). The analysis included 308 patients with CML in the chronic phase who were extracted from the CML Cooperative Study Group database. Of these patients, 11 (3.6%) were identified as having TR-CML. No differences in age, sex, white blood cell count, hemoglobin level, platelet count, or European Treatment and Outcome Study risk were observed between patients with TR-CML vs. de novo CML. However, the responses of TR-CML patients to TKIs (6, 3, and 2 received imatinib, nilotinib, and dasatinib, respectively) were excellent; all achieved major or deep molecular response. Furthermore, the outcomes of TR-CML patients were relatively favorable; the 3-year event-free survival rates in the TR-CML and de novo CML patients were 100% and 94%, respectively; the difference was not statistically significant. In conclusion, our study showed that TR-CML patients could achieve a good clinical course with TKI therapy. Detailed investigations of TR-CML may provide new insights into CML biology.

Clinical Entity and Outcomes of Therapy-Related Chronic Myeloid Leukemia in the Era of Tyrosine Kinase Inhibitors: Surveillance By the Chronic Myeloid Leukemia Cooperative Study Group

Background and Aim: Therapy-related chronic myeloid leukemia (TR-CML), which is defined as CML that developed after exposure to cytotoxic chemotherapy and/or radiotherapy, rarely exists in clinical practice, although its incidence rates are relatively lower than those of acute myeloid leukemia or myelodysplastic syndromes, accounting for 1.2-30.4% of secondary leukemias. The clinical behavior of TR-CML, including patient outcome, is reportedly not different from that of de novo CML before the era of imatinib treatment. While the recent advancement of CML treatment by the introduction of tyrosine kinase inhibitors (TKIs) has dramatically improved treatment outcomes in patients with CML, little is known about the treatment response and outcomes in patients with TR-CML treated with TKI. In this regard, we investigated the clinical entity of TR-CML in the era of TKIs, including treatment response to TKI and prognosis, in patients enrolled to the CML Cooperative Study Group.Patients and Methods: We retrospectively reviewed the data of patients enrolled in the CML Cooperative Study to identify patients diagnosed with TR-CML. This study included patients aged >15 years who were diagnosed with CML in the chronic phase between April 2001 and January 2016, and treated with any TKIs as initial therapy and followed up for at least 3 months. The study was approved by the research ethics board of each institution and conducted in accordance with the Declaration of Helsinki. A major molecular response (MMR) was defined as ≤0.1% on the International Scale (IS) or 100 copies of the BCR-ABL1 transcript/μg RNA in a transcription-mediated amplification and hybridization protection assay. A deep molecular response (DMR) was defined ≤0.0032% in the IS. Event-free survival (EFS) was defined as the period from the date of initial treatment with TKI to the date of onset of the first adverse event (loss of treatment efficacy, progression to the accelerated or blastic phase, or any cause of death) or the last follow-up. Statistical analyses were performed by using EZR.Results and Discussion: We identified 308 patients with newly diagnosed CML in the chronic phase, including 11 (3.6%) with TR-CML and 297 with de novo CML. Regarding the primary cancer, 2 of the 11 patients had breast cancer and the remaining 9 had prostate cancer, pharyngeal cancer, mesothelioma, lung cancer, colon cancer, ureter cancer, acute leukemia, gastric cancer, or bladder cancer, respectively. Eight cases were treated with chemotherapy, 2 were treated with radiotherapy, and the remaining case was treated with both chemotherapy and radiotherapy. The results of a cytogenetic analysis by G-banding were exclusive t(9;22)(q34;q11) in all the patients. The median time to diagnosis of CML from the initiation of chemotherapy and/or radiotherapy was 7 years (range, 1.2-33 years). No significant differences in patient age, sex, white blood cell count, hemoglobin level, platelet count, or European Treatment and Outcome Study risk were observed between the TR-CML and de novo CML groups. Among the patients whose cytogenetic and/or molecular responses were assessable, all had excellent treatment response to TKI. Seven patients unexpectedly reached MMR within 6 months after TKI initiation. Finally, 8 patients attained DMR or undetectable leukemia in the bone marrow and the remaining 3 attained MMR. The 5-year EFS of the patients in the de novo CML group was 90%. None of the patients in the TR-CML group experienced any adverse event. In conclusion, in the present study, we revealed that patients with TR-CML could attain a good clinical course with TKI therapy. Detailed investigations of TR-CML may provide new insights into the CML biology. DisclosuresIriyama:Novartis: Honoraria, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Speakers Bureau. Takaku:Bristol: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Nakazato:Mundipharma KK: Research Funding. Fujita:Chugai Pharmaceutical Co.,LTD: Honoraria. Tokuhira:Bristol Myers Squibb Co., Ltd: Honoraria; Pfizer Co., Ltd: Honoraria; Eizai Co., Ltd: Honoraria. Kawaguchi:Novartis: Honoraria.

Impact of Therapy-Related De Novo Acute Myeloid Leukemia on Response and Survival

determined by microarray analysis and validated by qRT-PCR. Future studies will address the mechanism of how PP2A regulates these miRs. Conclusion: Loss of B55 alpha PP2A activity in leukemia can induce diverse survival signaling pathways and allow expression of pro-tumor microRNAs. 207 Impact of Therapy-Related De Novo Acute Myeloid Leukemia on Response and Survival Koji Sasaki, Elias Jabbour, Hagop Kantarjian, Jorge Cortes, Guillermo Garcia-Manero, Gautam Borthakur, Sherry Pierce, Naveen Pemmaraju, Susan O’Brien, Farhad Ravandi Department of Leukemia, The University of Texas MD Anderson Cancer Center Background: The available data on outcome of patients with therapy-related de novo acute myeloid leukemia (t-de novo AML) without antecedent myelodysplastic syndrome (MDS) are limited. Methods: We retrospectively reviewed the records of patients with newly diagnosed AML who presented to MD Anderson Cancer Center between January 2000 and January 2014. T-de novo AML was defined as at least 20% blasts in bone marrow with a history of any previous cytotoxic chemotherapy or radiation therapy and without antecedent MDS. The overall survival (OS) and leukemiaTable 1 Characteristics and Outcomes of Patients with De Novo AM t-de novo AML (n[ 187) de n ( Age at diagnosis, median, years (range) 64 (21-89) 6 Prior radiation therapy, No. (%) 101 (54) Prior chemotherapy, No. (%) 186 (99) WBC count at diagnosis, median, 10/mL (range) 3.2 (0.2-191) 4. Hgb at diagnosis, median, g/dL (range) 9.1 (4.5-12.9) 9. Plt count at diagnosis, median, 10/mL (range) 34 (4-454) 5 LDH at diagnosis, median, IU/L (range) 1359 (210-22090) 118 PB blast percentage at diagnosis, median (range) 8 (0-98) 9. BM blast percentage at diagnosis, median (range) 41 (0-96) 4 Molecular genetic abnormalities at diagnosis, No. (%) FLT3-ITD 17 (9) 9 FLT3-D835 6 (3) 2 NPM1 7 (4) 10 JAK2 3 (2) RAS 17 (9) 5 free survival (LFS) in patients with t-de novo AML were compared to those with de novo AML with normal karyotype (NK) or complex karyotype (CK). Results: Of 1677 patients with newly diagnosed AML, 383 had de novo NK-AML, 218 had de novo CKAML, and 187 had t-de novo AML. The median follow-up was 9.3 months (range, 0.2-161.0). Patient characteristics and outcomes are summarized in Table 1. Of the 187 patients with t-de novo AML, 69 had a history of lymphoma; 63, breast cancer; 10, colon cancer; 10, sarcoma; and 69, another type of cancer. Fifteen of the patients with t-de novo AML (8%) had a favorable-risk karyotype, 53 patients (28%) an intermediate-risk karyotype, and 119 patients (64%) a poor-risk karyotype. The median LFS durations in t-de novo AML, NK-AML, and CK-AML were 7 months (95% confidence interval [CI], 5.1-8.7), 19 months (95%CI, 13.0-25.2), and 6 months (95%CI, 9.0-13.5) (P 100103/mL, platelets <30 0103/mL, nonfavorable cytogenetic abnormalities, positive RAS mutation, and the absence of complete remission or complete remission with incomplete platelet recovery as poor prognostic features related to OS. Conclusion: LFS and OS for patients with t-de novo AML were shorter than those for patients with NK-AML but did not differ significantly from those for patients with CK-AML.

Outcome of Patients (pts) with Therapy-Related De Novo Acute Myeloid Leukemia (t-de novo AML): Single Institution Experience

Background:Therapy-related myeloid neoplasms develop after cytotoxic chemotherapy or radiation therapy. The available data on the outcome of pts with t-de novo AML without antecedent history of myelodysplastic syndrome (MDS) is limited.Methods:We reviewed the records of pts with newly diagnosed AML who presented to our tertiary care center from 1/2000 to 1/2014. t-de novo AML was defined as having at least 20% blasts in bone marrow with a history of any previous cytotoxic chemotherapy or radiation therapy, and without an antecedent history of MDS. Leukemia-free survival (LFS) was defined as time from achieving complete response (CR) to relapse or death. The overall survival (OS) and LFS in pts with t-de novo AML were compared to those of with de novo AML with normal karyotype (NK) and complex karyotype (CK).Results:Among 1677 pts with newly diagnosed AML, 383 had de novo NK-AML, 218 had de novo CK-AML, and 187 had t-de novo AML. The median follow-up was 9.3 months (range; 0.2-161.0). Pt characteristics and outcomes are described in Table 1. Among the 187 pts, 69 had a history of lymphoma; 63 pts breast cancer (Ca); 10 pts colon Ca; 10 pts sarcoma; 8 pts prostate; 7 pts bladder Ca; 6 pts uterine Ca; 5 pts lung Ca; 5 pts head and neck Ca; 30 pts other type of Ca. Among the pts with t-de novo AML, 15 pts (8%) had a favorable-risk karyotype by WHO, 53 pts (28%) intermediate-risk karyotype, and 119 pts (64%) poor-risk karyotype. The median LFS duration in t-de novo AML, NK-AML, and CK-AML were 7 months (95% confidence interval [CI]; 5.1-8.7), 19 months (95% CI; 13.0-25.2), and 6 months (95% CI; 9.0-13.5) (p<.001), respectively. The median OS duration in t-de novo AML, NK-AML, and CK-AML were 7 months (95% CI; 5.9-8.9), 21 months (95% CI; 16.2-25.5), and 12 months (95%CI; 10.6-13.5) (p<.001), respectively. The results of univariate (UVA) and multivariate analysis (MVA) associated with OS were summarize in Table 1. MVA identified age over 60, white blood cell count (WBC) over 10 x103/µL, thrombocytopenia below 30 x103/µL, non-favorable cytogenetic abnormalities, positive RAS mutation, and the absence of CR or CR with incomplete platelet recovery (CRp) as poor prognostic features related to OS.Conclusion:LFS and OS were shorter in patients with t-de novo AML than in those with NK-AML but did not differ significantly from patients with CK-AML.Abstract 2273. Table 1Patient Characteristics and Outcomest-de novo AML [n= 187]de novo AML with NK [n= 383]de novo AML with CK [n= 218]PAge at diagnosis, median (years)64 (21-89]63 (17-90)67 (18-87)Prior radiation therapy, No. (%)101 (54)00Prior chemotherapy, No. (%)186 (99)00White blood cell count at diagnosis, median (x103/µL)3.2 (0.2-191)4.3 (0.2-390.0)2.9 (0.5-278.2)Hemoglobin at diagnosis, median (g/dL)9.1 (4.5-12.9)9.1 (4-14.6)9.0 (2.5-14.2)Platelet count at diagnosis, median (x103/µL)34 (4-454)51 (3-469)42 (2-319)LDH at diagnosis, median (IU/L)1359 (210-22090)1189 (200-42000)1274 (231-20572)Peripheral blood blast percent at diagnosis, median (%)8 (0-98)9.5 (0-98)10 (0-98)Bone marrow blast percent at diagnosis, median (%)41 (0-96)44 (0-96)33 (0-97)Molecular genetic abnormalities at diagnosis, No. (%)FLT3-ITD17 (9)96 (25)5 (2)FLT3-D8356 (3)23 (6)1 (1)NPM17 (4)104 (27)4 (2)JAK23 (2)6 (2)8 (4)RAS17 (9)50 (13)8 (4)RUNX1-RUNX1T14 (2)00CBFb-MYH6 (3)00Response, No. (%)<0.001Complete response89 (48)237 (62)76 (35)Complete response without platelet recovery15 (8)1 (0)15 (7)1-year LFS, (%)336027<0.0012-year LFS, (%)335220<0.0011-year OS, (%)346830<0.0012-year OS, (%)244613<0.001UVA and MVA of OS in t-de novo AMLUVAMVAHazard ratio95% CIAge at diagnosisAge =< 60 years-Age >60 years< .001.0012.2381.417-3.534White blood cell count (WBC) (x103/µL)WBC =< 10.0-WBC > 10.0.002.0371.6171.030-2.540Hemoglobin (Hgb) (g/dL)Hgb >= 8-Hgb < 8.749Platelet count (Plt) (x103/µL)Plt >= 30-Plt < 30.008.0041.8521.224-2.803LDH (IU/L)LDH =<1000-LDH > 1000.640Peripheral blood blast percent (PB blast)(%)PB blast =< 10%-PB blast >10%.178Bone marrow blast percent (BM blast) (%)BM blast =<40%-BM blast >40%.393Cytogenetic abnormalityFavorable-Non-Favorable.002.0195.8361.342-25.370FLT3-ITDNegative-Positive.768RASNegative-Positive.047.0032.5761.367-4.856ResponseCR or CRp-Non-CR or CRp<.001.009.3310.145-0.757CR-Non-CR<.0010.903.9500.418-2.160 [Display omitted] DisclosuresKantarjian:ARIAD, Pfizer, Amgen: Research Funding.

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.

RUNX1 Mutations in Clonal Myeloid Disorders: From Conventional Cytogenetics to Next Generation Sequencing, A Story 40 Years in the Making

Translocations and mutations in the core binding factor genes, RUNX1 or CBFB, are found in acute myeloid and lymphocytic leukemia, therapy-related myeloid leukemia, myelodysplastic syndrome, chronic myelomonocytic leukemia, and in familial platelet disorder with predisposition to acute myeloid leukemia. Here we review the biochemical and biological properties of the normal Runx1 protein, discuss the nature of RUNX1 mutations in myeloid leukemia, their prognostic significance, and the mutations that cooperate or co-exist with them in these various diseases.

Cellular Response to Cytarabine Is Modulated by the DNA Mismatch Repair Pathway: Implications for Treatment of Acute Myeloid Leukemia

AbstractAbstract 1819The DNA mismatch repair (MMR) pathway is responsible for repair of spontaneous errors arising during DNA replication, thus maintaining the integrity of the genome. DNA MMR is frequently dysregulated in some forms of leukemia. We and others have shown that microsatellite instability, the hallmark of dysfunctional DNA MMR, is present in up to 90% of therapy-related myeloid leukemia, 50% of relapsed myeloid leukemia, but is rarely seen in de novo leukemia. Paradoxically, functional MMR mediates the cytotoxicity of certain chemotherapeutic agents, particularly methylating agents and the nucleoside analogue 6-thioguanine (6-TG), and dysregulation of the MMR pathway confers tolerance to these agents. In the present study, using cell lines harboring defects in MMR components, we show that MMR status also modulates response to the nucleoside analogue cytarabine (Ara-C) and to other therapeutic nucleoside analogues commonly used in the treatment of leukemia. We initially determined gene and protein expression levels of the major MMR components (MSH2, MSH3, MSH6, MLH1 and PMS2) in two psuedo-isogenic cell line pairs, and investigated the ability of cell extracts to bind to defined mismatches in electrophoretic mobility shift assays. In cytotoxicity assays, the cell lines HL-60R (which demonstrates 200-fold overexpression of MSH3) and MT-1 (which lacks functional MSH6 due to bi-allelic gene mutation) were tolerant to the cytotoxic effects of a methylating agent, methylnitrosourea (MNU), and 6-TG, relative to their respective parental cell lines. We also generated a panel of fully isogenic MMR-defective cell lines in which either MSH2, MSH3 or MSH6 protein was reduced to almost negligible levels using short hairpin RNA-mediated gene knockdown. Knockdown of either MSH2 or MSH6 conferred tolerance to the killing effects of MNU and 6-TG by virtue of loss of MutSα activity (a heterodimer of MSH2 and MSH6 responsible for recognition of base:base mispairs), whereas knockdown of MSH3 did not affect cellular response to these agents. Consistent with a role for MMR in affecting cellular response to other nucleoside analogues used to treat leukemia, the cell lines also displayed differential toxicity to the killing effects of Ara-C, clofarabine, cladribine and fludarabine compared to their MMR-proficient parental counterparts, however the exact response was dependent on the specific nature of the MMR defect. Cell lines with a reduction in MSH2 protein demonstrated hypersensitivity to cytotoxicity induced by these nucleoside analogues. Conversely, MSH3 knockdown conferred resistance to the cytotoxic effects of these agents. These data suggest that DNA MMR can affect response to nucleoside analogues via multiple mechanisms, and may also involve interaction of DNA MMR components with other DNA repair pathways. One possibility is that these agents induce base lesions in DNA recognized by DNA MMR components. Consistent with this model, we have shown that Ara-C induces DNA polymerase slippage in vitro, generating a substrate potentially recognized by MutSβ (a heterodimer of MSH2 and MSH3 responsible for recognition of small insertions and extrahelical loops). Furthermore, we have also shown that Ara-C is mutagenic at the thymidine kinase and hypoxanthine-guanine phosphoribosyltransferase loci in the TK6 cell line. Taken together, these data suggest that cellular MMR status affects response to nucleoside analogues and furthermore, the specific nature of the defect is important in determining the exact response. These findings have implications for the use of nucleoside analogues in the treatment of cancers where MMR dysfunction has been identified to occur with high frequency, such as therapy-related and relapsed acute myeloid leukemia. Disclosures:No relevant conflicts of interest to declare.

Abstract 1962: DNA mismatch repair status modulates cellular response to cytarabine: Implications for treatment of acute myeloid leukemia

Abstract The DNA mismatch repair (MMR) pathway is responsible for repair of spontaneous errors arising during DNA replication, thus maintaining the integrity of the genome. DNA MMR is frequently dysregulated in some forms of leukemia. We and others have shown that microsatellite instability, the hallmark of dysfunctional DNA MMR, is present in up to 90% of therapy-related myeloid leukemia, 50% of relapsed myeloid leukemia, but is rarely seen in de novo leukemia. Paradoxically, functional MMR mediates the cytotoxicity of certain chemotherapeutic agents, particularly methylating agents and the nucleoside analogue 6-thioguanine, and dysregulation of the MMR pathway confers tolerance to these agents. In the present study, using cell lines harbouring defects in MMR components, we show that MMR status also modulates response to the nucleoside analogue cytarabine and to other therapeutic nucleoside analogues commonly used in the treatment of leukemia. We have determined gene and protein expression levels of the major MMR components in a panel of 4 psuedo-isogenic cell line pairs, and investigated the ability of cell extracts to bind to defined mismatches in electrophoretic mobility shift assays. The cell lines HL-60R (which demonstrates 200-fold overexpression of MSH3) and MT-1 (which lacks functional MSH6 due to bi-allelic gene mutation) were tolerant to the cytotoxic effects of methylating agents and 6-thioguanine by virtue of loss of MutSα activity. However, two additional cell lines, TK6 MTXR and PreB697 MTXR (which demonstrate approximately 5-fold and 2-fold overexpression of MSH3 respectively), did not demonstrate differential response to the cytotoxic effects of methylating agent or 6-thioguanine, suggesting that relatively modest MMR defects do not significantly perturb the pathway. Consistent with a role for MMR in affecting cellular response to other nucleoside analogues used to treat leukemia, those cell lines with major defects in MMR (HL-60R and MT-1) displayed differential toxicity to the killing effects of cytarabine, clofarabine, cladribine and fludarabine compared to their MMR-proficient parental counterparts. In contrast, those cell lines with modest perturbation of the MMR pathway did not respond differently to their parental counterparts following treatment with these agents. Taken together, these data suggest that cellular MMR status affects response to nucleoside analogues and furthermore, the specific nature of the defect is important in determining the exact response. These findings have implications for the use of nucleoside analogues in the treatment of cancers where MMR dysfunction has been identified to occur with high frequency, such as therapy-related and relapsed acute myeloid leukemia. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1962.

Therapy-Related Chronic Myeloid Leukemia and Myelodysplastic Syndrome with -7, t(9;22), and 5q-, t(9;22).

Abstract 4726 IntroductionTherapy-related hematologic diseases are known to include acute myelocytic leukemia (AML) and myelodysplastic syndromes (MDS), but reports of therapy-related chronic myeloid leukemia (CML) are rare. Philadelphia chromosome-positive (Ph+) CML has been described in patients who were previously exposed to alkylating agents or topoisomerase II inhibitors. Below, we present a patient with Ph+ CML and MDS with both monosomy 7 (-7) and deletion of the long arm of chromosome 5 (5q-) following chemotherapy and radiation for pleomorphic liposarcoma. CaseAn 80 year old African American man was diagnosed with pleomorphic liposarcoma involving his right thigh fourteen years ago. He received six cycles of peri-operative chemotherapy with cyclophosphamide, doxorubicin and dacarbazine, and adjuvant radiation therapy. Six years later, he received seven cycles of dacarbazine, ifosfamide/mesna and etoposide peri-operatively for a recurrence in the abdomen. Twelve years later, he received sixteen cycles of gemcitabine and docetaxel for another intra-abdominal recurrence, with disease progression. He then received a study drug, ANG (1-7) for a year, with disease progression. This was treated with radiation therapy to the abdominal site, completed three months ago. On routine follow up, he was doing well and had an unremarkable physical examination. A CT scan of his abdomen revealed stable disease. He was noted to have a WBC count of 30,000/microliter with 61% segmented neutrophils, 5% band neutrophils, 6% metamyelocytes, 4% myelocytes, 2% basophils, 1% eosinophils, 14% monocytes and 7% lymphocytes. Hemoglobin was 12.6 grams/deciliter and platelets 129,000/microliter. A bone marrow biopsy showed marked granulocyte hyperplasia with large paratrabecular aggregates of immature myeloid precursors. Megakaryocytes were increased in number with dysplastic features including small, hyperchromatic and hypolobated forms. There was frequent clustering. There were no dysplastic features in the erythroid cell line. Background hematopoiesis was decreased. There was no increase in blasts. 11 cells were karyotyped with a band resolution of 450, revealing 2 cell lines. One was an abnormal clonal male cell line with t(9;22) and monosomy 7. The other, had t(9;22) and deletion of the long arm of chromosome 5. Peripheral blood RT-PCR for BCR-ABL gene rearrangement quantitation showed a ratio of 1.607 of fusion transcript to control. A diagnosis of therapy-related CML in chronic phase and MDS was thus made. His IPSS score is intermediate-1. He is currently on imatinib mesylate, which he is tolerating well. After 2 weeks of therapy, his WBC count was 7,800/microliter with a normal differential count, hemoglobin 10.7 grams/deciliter and platelets 86,000/microliter. DiscussionThe presence of -7 and t(9;22) in one cell line, and 5q- and t(9;22) in the other implies that the t(9;22) may have been an earlier event. Abnormalities in chromosome 5 and 7 are typically associated with therapy-related MDS and AML following exposure to alkylating agents, and carry a poor prognosis. The abnormalities involving chromosomes 5 and 7 affecting the cells carrying the t(9;22) overwhelmingly support a diagnosis of therapy-related CML. Topoisomerase II inhibitors have been associated with therapy-related AML with balanced translocations involving the chromosome bands 11q23 and 21q22. The t(9;22) could have arisen as a result of mitotic, non-homologous chromosomal recombination of topoisomerase II-induced double-strand breaks of DNA. In this case, CML is the presenting diagnosis of therapy-related malignant hematologic disease. This patient was initiated on treatment for CML, but close follow up will be maintained regarding his MDS. ConclusionTherapy-related CML should be considered in patients who have had chemotherapy and/or radiation. It may present prior to the onset of other more fatal therapy-related hematologic disorders, and therefore has implications on treatment and long term follow up. Disclosures:Powell:Novartis Pharmaceuticals: Research Funding.

Genome-wide association study to identify novel loci associated with therapy-related myeloid leukemia susceptibility

AbstractTherapy-related acute myeloid leukemia (t-AML) is a rare but fatal complication of cytotoxic therapy. Whereas sporadic cancer results from interactions between complex exposures and low-penetrance alleles, t-AML results from an acute exposure to a limited number of potent genotoxins. Consequently, we hypothesized that the effect sizes of variants associated with t-AML would be greater than in sporadic cancer, and, therefore, that these variants could be detected even in a modest-sized cohort. To test this, we undertook an association study in 80 cases and 150 controls using Affymetrix Mapping 10K arrays. Even at nominal significance thresholds, we found a significant excess of associations over chance; for example, although 6 associations were expected at P less than .001, we found 15 (Penrich = .002). To replicate our findings, we genotyped the 10 most significantly associated single nucleotide polymorphisms (SNPs) in an independent t-AML cohort (n = 70) and obtained evidence of association with t-AML for 3 SNPs in the subset of patients with loss of chromosomes 5 or 7 or both, acquired abnormalities associated with prior exposure to alkylator chemotherapy. Thus, we conclude that the effect of genetic factors contributing to cancer risk is potentiated and more readily discernable in t-AML compared with sporadic cancer.

Rearrangements of the MLL Gene Are Influenced by DNA Secondary Structure, Potentially Mediated by Topoisomerase II Binding

Rearrangements of the MLL gene are found in approximately 75–80% of both infant acute leukemia (IAL) and therapy related myeloid leukemia (tAML), the latter linked to prior exposure to Topoisomerase II inhibitors. In order to study the mechanism whereby such rearrangements are induced, a fine mapping screen was performed using Inverse PCR to analyze a MLL location at the intron 11/exon 12 border that is known to be a hot spot for the induction of DNA breaks and rearrangements. Human lymphoblastoid TK6 cells were exposed to the pro-apoptotic agent anti-CD95 and estrogen as both the apoptotic process and birth control formulations have been associated with the development of MLL-linked leukemia. The latter association was determined as part of an epidemiological analysis of IAL. In addition, blood samples from patients receiving Topoisomerase II inhibitor therapy, subsequent to a diagnosis of breast cancer or lymphoma, were examined in the same manner as such drugs are strongly associated with the etiology of tAML. From an initial screen of cells treated in-vitro, 13/27 of all rearrangement break points (translocations/insertions) were located within a 3 bp tract at the 5′ edge of a 10 bp palindrome that defined a potential 101 bp stem-loop with its 3′ palindrome partner. Analysis of blood samples taken up to a year after treatment initiation from lymphoma and breast cancer patients, showed a similar distribution of translocations with 10/20 events restricted to the same location on the 5′ of the palindrome. Further examination of the putative stem-loop structure showed a high stringency Topoisomerase II consensus sequence binding site at the geometric midpoint of the proposed stem-loop. In order to link the rearrangements observed with DNA cleavage events, TK6 cells exposed to anti-CD95 antibody were also screened for DNA breaks within the same region of MLL. Here, LM-PCR products spanning the region of interest were extracted from DNA gels and the location of cleavage determined by cloning and sequencing. From four to twenty four hours after anti-CD95 exposure, analysis of the breaks induced showed 24/37 (65%) were located at the base of the proposed stem loop associated with the DNA palindrome. 14/37 (38%) of breaks were found within a 40 bp tract at the 5′ side and 10/37 (27%) within a 20 bp tract at the 3′ side of the palindrome base. In each case, the hot spots for cleavage identified by LM-PCR included the palindromic sequences. Thus, unlike the 5′ restriction of MLL rearrangements, DNA fragmentation occurred at both sides of the proposed stem loop base, indirectly supporting the creation of such a structure in-vivo that is subject to local attack at the stem base. Palindrome association may be driven by the bending Topoisomerase II exerts when bound at the midpoint between each palindrome, such that each half of the proposed palindrome is brought into physical contact. This effect would be accentuated by poisoning of Topoisomerase II, subsequent to binding of drugs such as etoposide that stabilize the cleavable complex. We propose a model for a sub-group of MLL rearrangements that utilize Topoisomerase II mediated stabilization, either natively or subsequent to chemical poisoning, to assist in the creation of stable DNA structures that are permissive for DNA fragmentation. Further, the conversion of DNA double strand breaks at these sites to detectable rearrangements may be influenced by 5′ to 3′ DNA processing functions, such as transcription or replication.

Therapy-Related Myeloid Leukemia

Therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/t-AML) are thought to be the direct consequence of mutational events induced by chemotherapy, radiation therapy, immunosuppressive therapy, or a combination of these modalities, given for a pre-existing condition. The outcomes for these patients have been poor historically compared to people who develop de novo AML. The spectrum of cytogenetic abnormalities in t-AML is similar to de novo AML, but the frequency of unfavorable cytogenetics, such as a complex karyotype or deletion or loss of chromosomes 5 and/or 7, is considerably higher in t-AML. Survival varies according to cytogenetic risk group in t-AML patients, with better outcomes being observed in those with favorable-risk karyotypes. Treatment recommendations should be based on performance status and karyotype. A deeper understanding of the factors that predispose patients to the development of therapy-related myeloid leukemia would help clinicians monitor patients more carefully after treatment for a primary condition. Ultimately, this knowledge could influence initial treatment strategies with the goal of decreasing the incidence of this serious complication.

Rituximab associated to imatinib for coexisting therapy-related chronic myeloid leukaemia and relapsed non-Hodgkin lymphoma

Philadelphia positive (Ph+) chronic myeloid leukaemia (CML) presenting synchronously or following non-Hodgkin lymphoma (NHL) has only rarely been reported. Herein, we refer on a case of Ph+ CML occurring after a breast cancer and a NHL with multiple relapses. After obtaining complete cytogenetic remission with imatinib, the patient presented a new NHL relapse, that was treated with rituximab concomitantly to imatinib. Therapy was well tolerated and the patient is presently alive in complete remission of either NHL and CML. We also reviewed the literature relating the uncommon association of these two unrelated diseases.

Etiology and Management of Therapy-Related Myeloid Leukemia

The diagnosis of therapy-related myeloid leukemia (t-MDS/t-AML) identifies a group of high-risk patients with multiple and varied poor prognostic features. These neoplasms are thought to be the direct consequence of mutational events induced by cytotoxic therapy. Their outcomes have historically been poor compared with those of people who develop acute myeloid leukemia (AML) de novo. The question arises whether a diagnosis of t-AML per se indicates a poor prognosis, or whether their bad outcomes result from other clinical and biologic characteristics. Because of lingering damage from prior cytotoxic therapy and, in some cases, the persistence of their primary disorder, patients with t-AML are often poor candidates for intensive AML therapy. The spectrum of cytogenetic abnormalities in t-AML is similar to de novo AML, but the frequency of unfavorable cytogenetics, such as a complex karyotype or deletion or loss of chromosomes 5 and/or 7, is higher in t-AML. Survival varies according to cytogenetic risk group, with better outcomes observed in patients with t-AML with favorable-risk karyotypes. Treatment recommendations should be based on performance status and karyotype. Patients with t-AML should be enrolled on front-line chemotherapy trials, appropriate for de novo AML patients with similar disease characteristics. Allogeneic hematopoietic cell transplantation can cure some patients with t-AML. Most important , the molecular and genetic differences that appear to determine the phenotype and the outcome of these patients need to be investigated further.