Loss of heterozygosity in 7q myeloid disorders: clinical associations and genomic pathogenesis

Loss of heterozygosity affecting chromosome 7q is common in acute myeloid leukemia and myelodysplastic syndromes, pointing toward the essential role of this region in disease phenotype and clonal evolution. The higher resolution offered by recently developed genomic platforms may be used to establish more precise clinical correlations and identify specific target genes. We analyzed a series of patients with myeloid disorders using recent genomic technologies (1458 by single-nucleotide polymorphism arrays [SNP-A], 226 by next-generation sequencing, and 183 by expression microarrays). Using SNP-A, we identified chromosome 7q loss of heterozygosity segments in 161 of 1458 patients (11%); 26% of chronic myelomonocytic leukemia patients harbored 7q uniparental disomy, of which 41% had a homozygous EZH2 mutation. In addition, we describe an SNP-A-isolated deletion 7 hypocellular myelodysplastic syndrome subset, with a high rate of progression. Using direct and parallel sequencing, we found no recurrent mutations in typically large deletion 7q and monosomy 7 patients. In contrast, we detected a markedly decreased expression of genes included in our SNP-A defined minimally deleted regions. Although a 2-hit model is present in most patients with 7q uniparental disomy and a myeloproliferative phenotype, haplodeficient expression of defined regions of 7q may underlie pathogenesis in patients with deletions and predominant dysplastic features.     

Predictive factors for latency period and a prognostic model for survival in patients with therapy‐related acute myeloid leukemia

Therapy‐related acute myeloid leukemia (t‐AML) is an increasingly recognized sequela in patients receiving chemotherapy or radiotherapy for a primary malignancy or autoimmune disease. This study assessed factors related to the latency period (LP) between the antecedent disorder (AD) and t‐AML diagnosis and developed a comprehensive prognostic model to predict overall survival (OS). We evaluated a cohort of newly diagnosed t‐AML patients treated with cytarabine‐based induction therapy from 2001 to 2011. Multivariable linear and proportional hazards models were used to assess the impact of different classes of chemotherapy on the LP and to identify independent prognostic factors for OS. Of 730 treated AML patients, 58 (7.9%) had t‐AML. Median LP to t‐AML was 5.6 years (range, 0.5–38.4). 64% of patients achieved CR and median OS was 10.7 months. Independent prognostic factors of short LP were age at AD (P < 0.0001) and prior treatment with mitotic inhibitors (P = 0.05). Unfavorable cytogenetics (P = 0.004), antecedent hematologic or autoimmune disease (P = 0.01), age >60 (P = 0.03), and platelet count <30,000 μL (P = 0.04) at the time of t‐AML diagnosis were prognostic for inferior OS. A prognostic model using these factors was developed that risk stratified t‐AML patients into two groups: favorable and unfavorable. Patients in the favorable group had a median OS of 37.6 months compared with 6.4 months in patients comprising the unfavorable group (P < 0.0001). Multicomponent prognostic models integrating disease or treatment‐related covariates can help better understand how t‐AML evolves; and can be clinically useful in risk stratifying t‐AML patients undergoing induction therapy. Am. J. Hematol. 89:168–173, 2014. © 2013 Wiley Periodicals, Inc.     

Large granular lymphocytic leukaemia after solid organ and haematopoietic stem cell transplantation

T-cell large granular lymphocytic leukaemia (T-LGLL) is a chronic clonal lymphoproliferative disorder of cytotoxic T lymphocytes which commonly occurs in older patients and is often associated with autoimmune diseases. Among 246 patients with T-LGLL seen at our institution over the last 10 years, we encountered 15 cases following solid organ or haematopoietic stem cell transplantation. Here, we studied the clinical characterization of these cases and compared them to de novo T-LGLL. This experience represented a clear picture of the intricate nature of the disease manifestation and the complexities of several immune mechanisms triggering the clonal expansion.     

Older adults with acute myeloid leukemia

Acute myeloid leukemia (AML) occurs most frequently in older adults, with a median age range from 65 to 70 years. Both the disease and its treatment are distinct from their counterparts in young patients. Herein we characterize the intrinsic biologic features of AML as it occurs in the older population, review currently available therapeutic approaches, and discuss therapeutic strategies in development.     

Clofarabine for myelodysplastic syndromes

INTRODUCTION: Treatment options in myelodysplastic syndromes (MDS) remain limited. The introduction of novel therapies that can improve response rates and survival outcomes in MDS remains a challenge. Clofarabine is a purine nucleoside analog that works primarily via inhibition of DNA biosynthesis and the ribonucleotide reductase enzyme with recent evidence suggesting that at low doses it may affect DNA methylation. It has been successfully used in the treatment of acute myeloid leukemia (AML) and is under investigation in MDS. AREAS COVERED: A PubMed search for articles pertaining to clofarabine was conducted and streamlined to only include data on MDS or AML that evolved from MDS. Also included were clofarabine-related response and safety data from presentations at the 52(nd) Annual American Society of Hematology Meeting in Orlando, Florida, USA. EXPERT OPINION: Clinical trials using clofarabine in MDS and MDS/myeloproliferative neoplasms have produced overall response rates of 31 - 43% including complete responders. Although myelosuppression is an important side effect, clofarabine is generally well tolerated in MDS. Clofarabine is currently available in an intravenous form with an oral formulation presently under investigation, either as a single agent or in combination therapy in MDS. Larger studies may help clarify the viability of clofarabine in the treatment of MDS patients.     

White blood cell count nadir following remission induction chemotherapy is predictive of outcome in older adults with acute myeloid leukemia

Kinetics of white blood cell (WBC) elimination following induction chemotherapy for older adults with acute myeloid leukemia (AML) may serve as a surrogate for its effectiveness and safety by enabling real-time prognostication. We reviewed 122 older adults with AML treated at the Cleveland Clinic. Recursive partitioning analysis was used to identify optimal cut points in nadir WBC count and time to WBC nadir that correlate with survival. Multivariable analysis identified time to WBC nadir less than or equal to 10 days (HR 2.15, 95%CI 1.12 - 4.12, p = 0.02), low WBC nadir (less than 0.04×10⁹/l, HR 2.68, 95%CI 1.15 - 6.23, p = 0.02) and high WBC nadir (greater than 0.12×10⁹/l HR 1.5, 95%CI 0.96 - 2.37, p = 0.08), as predictors of worse outcomes. Time to WBC nadir predicts survival. The absolute WBC nadir value follows a J-curve, with lower value indicating a worse outcome.