Insights into the biologic and molecular abnormalities in adult acute lymphocytic leukemia

The functional role of microRNA in acute lymphoblastic leukemia: relevance for diagnosis, differential diagnosis, prognosis, and therapy

MicroRNAs (miRNAs), a new class of noncoding RNAs, which can hybridize to target messenger RNAs and regulate their expression posttranscriptionally, express differentially in distinct stages of lymphopoiesis and influence the direction of lymphoid precursor maturation. Hence, there is aberrant expression of miRNAs involved in malignant lymphopoiesis, and these aberrations can be used as signatures of acute lymphoblastic leukemia (ALL) with different subtypes. In addition, changes in the expression of several miRNAs may have functional relevance with leukemogenesis or drug resistance. As a result, the reversal of the expression of these miRNAs may alleviate the disease to some extent and improve clinical outcomes. However, among the studies of miRNAs, there are still some problems that need to be solved to understand the function of miRNAs in ALL more thoroughly.

Diagnosis and subclassification of acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a disseminated malignancy of B- or T-lymphoblasts which imposes a rapid and accurate diagnostic process to support an optimal risk-oriented therapy and thus increase the curability rate. The need for a precise diagnostic algorithm is underlined by the awareness that both ALL therapy and related success rates may vary greatly between ALL subsets, from standard chemotherapy in patients with standard-risk ALL, to allotransplantation (SCT) and targeted therapy in high-risk patients and cases expressing suitable biological targets, respectively. This review summarizes how best to identify ALL and the most relevant ALL subsets.

Immunophenotypic, Cytogenetic and Clinical Features in Chinese Adult Acute Lymphoblastic Leukaemia (ALL) Patients

Introduction: This study sought to investigate the immunophenotypic subtype profiles of 110 Chinese adult patients with acute lymphoblastic leukaemia (ALL) and its association to cytogenetics and the clinical features. Materials and Methods: A total of 110 adult patients with ALL were immunophenotyped by CD45/SSC double parameters and 4 colour flow cytometry. Seventy-three cases were also subjected to karyotype analysis by R-banding technology. The clinical and laboratory data of 110 ALL patients were retrospectively analysed. Results: Of all the patients, 21.8% were identified as T-ALL, 78.2% as B-ALL. Abnormal karyotypes were detected in 37 out of 73 (50.7%) cases and the most common cytogenetic abnormality was the Philadelphia (Ph) chromosome, which was found in 23.3% (17/73) of the cases. Myeloid antigen (MyAg) expression was documented in 47.3% of the 110 adult ALL cases analysed and CD13 was the most commonly expressed MyAg in ALL patients (32.1 %). No difference was observed in the expression of MyAg between the groups of patients with T-ALL (45.8%) and B-ALL (47.7%). Our data showed that older age, higher CD34 positivity and lower proportion of patients with splenomegaly were found to be correlated with MyAg+ ALL, and that patients with Ph+ B-ALL were older, presented with higher haemoglobin level and higher CD34 expression. No statistical difference was noted in complete remission (CR) rate, relapse rate, induction mortality or total death rate among My+ and My-, Ph+ and Ph-, or B-ALL and T-ALL patients. Conclusion: Our results indicate that the distribution of ALL in Chinese adult patients was similar with the general distribution pattern in the other countries, and the expression of MyAg in patients with T-ALL and B-ALL was comparable. Both the expression of MyAg and the presence of Ph chromosome in adult ALL were significantly associated with median age and CD34 expression while not with the response to induction treatment. Key words: Biological characteristics, Cytogenetics, Immunophenotype

Adult acute lymphoblastic leukemia: concepts and strategies

Acute lymphoblastic leukemia (ALL), a clonal expansion of hematopoietic blasts, is a highly heterogeneous disease comprising many entities for which distinct treatment strategies are pursued. Although ALL is a success story in pediatric oncology, results in adults lag behind those in children. An expansion of new drugs, more reliable immunologic and molecular techniques for the assessment of minimal residual disease, and efforts at more precise risk stratification are generating new aspects of adult ALL therapy. For this review, the authors summarized pertinent and recent literature on ALL biology and therapy, and they discuss current strategies and potential implications of novel approaches to the management of adult ALL. Cancer 2010. (c) 2010 American Cancer Society.

A Review of Nelarabine in the Treatment of T-cell Lymphoblastic Leukemia/Lymphoma

Patients with relapsed/refractory T-cell acute lymphocytic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) have a dismal prognosis. Prior to the development of novel purine analogs, salvage chemotherapy was of limited efficacy. Nelarabine, and more recently, clofarabine and forodesine have demonstrated significant anti-tumor activity in relapsed/refractory T-ALL and T-LBL. As a single agent, nelarabine induces response rates in between 33% to 50% of adult or pediatric patients with T-ALL/T-LBL, respectively. On the other hand, limited activity was observed in mature T-cell neoplasms. Significant neurotoxicity has been the major obstacle for the further clinical development of nelarabine. Alternative dose-schedules for administration have been evaluated with some degree of success. Ongoing clinical studies are integrating nelarabine in the front-line chemotherapy regimens for patients with T-ALL/T-LBL in pediatric and young adult patients. The current work summarizes the pre-clinical and clinical evaluation of nelarabine, a chemotherapy agent whose development demonstrates that industry, government agencies, and academia can effectively collaborate together to improve the patient outcomes with highly resistant/refractory rare hematological malignancies.

Adult acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) in adults is a relatively rare neoplasm with a curability rate around 30% at 5 years. This consideration makes it imperative to dissect further the biological mechanisms of disease, in order to selectively implement an hitherto unsatisfactory success rate. The recognition of discrete ALL subtypes (some of which deserve specific therapeutic approaches, like T-lineage ALL (T-ALL) and mature B-lineage ALL (B-ALL)) is possible through an accurate combination of cytomorphology, immunophenotytpe and cytogenetic assays and has been a major result of clinical research studies conducted over the past 20 years. Two-three major prognostic groups are now easily identifiable, with a survival probability ranging from <10 to 20% (Philadelphia-positive ALL) to about 50-60% (low-risk T-ALL and selected patients with B-lineage ALL). These issues are extensively reviewed and form the basis of current knowledge. The second major point relates to the emerging importance of studies that reveal a dysregulated gene activity and its clinical counterpart. It is now clear that prognostication is a complex matter ranging from patient-related issues to cytogenetics to molecular biology, including the evaluation of minimal residual disease (MRD) and possibly gene array tests. On these bases, the role of a correct, highly personalised therapeutic choice will soon become fundamental. Therapeutic progress may be obtainable through a careful integration of chemotherapy, stem cell transplantation, and the new targeted treatments with highly specific metabolic inhibitors and humanised monoclonal antibodies.

Immunophenotypes and outcome of Philadelphia chromosome-positive and -negative Thai adult acute lymphoblastic leukemia

Little evidence exists in Asian countries regarding the incidence, immunologic characteristics, and clinical outcomes of adult patients with Philadelphia chromosome-positive (Ph+) and -negative (Ph-) acute lymphoblastic leukemia (ALL). In this study, we prospectively studied 324 Thai adult acute leukemia patients, 79 (24%) of whom were identified as having ALL. Immunophenotyping was performed by 5-parameter flow cytometry, and karyotyping was conducted by standard banding methods. The Ph chromosome was detected in 18.5% of cases. The mean age of Ph+ ALL patients was 29 years (50% male), and that of Ph- ALL patients was 33 years (62% female). The Ph+ ALL patients had significantly higher white blood cell (WBC) counts (mean, 93 x 10(9)/L), with 67% having WBC counts higher than 50 x 10(9)/L. In contrast, most Ph- ALL patients had WBC counts lower than 50 x 10(9)/L (mean, 36 x 10(9)/L; P < .05). CD10 and CD34 were more highly expressed in the Ph+ ALL patients (mean expression, 83% and 87%, respectively) than in the Ph- ALL patients (45% and 57%; P < .005). The aberrant expression of myeloid antigens, including CD33 and CD13, was also significantly observed in the Ph+ ALL patients. The median survival time of Ph+ ALL patients was 8 months, compared with 22 months for the Ph- ALL patients. In conclusion, immunophenotyping results showed that Ph+ ALL in Thai adults arises from B-cells at an earlier stage of development. Extreme leukocytosis, a younger age, male sex, high expression levels of CD10 and CD34, aberrant myeloid antigens, and poorer rates of survival appeared to be associated with the Ph chromosome in Thai adult ALL cases. The incidence of the Ph chromosome among Thai adult ALL patients was not different from that found in Western countries.

The biology and therapy of adult acute lymphoblastic leukemia

BACKGROUND

Much progress has been made in understanding the biology of acute lymphoblastic leukemia (ALL). This has translated into the recognition of several subgroups of ALL and the institution of risk-adapted therapies. New therapies are emerging based on the definition of specific cytogenetic-molecular abnormalities.

METHODS

A review from the English literature, including original articles and related reviews from Medline (Pubmed) and abstracts based on publication of meeting material, was performed.

RESULTS

Changes in the pathologic classification of ALL have led to therapeutic consequences. Adaptation of successful treatment strategies in children with ALL has resulted in similar complete response rates in adults. Prognosis has especially improved in mature-B-cell and T-lineage ALL. The role of tyrosine kinase inhibitors in Philadelphia chromosome-positive ALL was evaluated in the current study. However, regardless of the ALL subgroup, long-term survival of adults is still inferior to that in children.

CONCLUSIONS

Intense clinical and laboratory research is attempting to close the gap in outcome between children and adults with ALL. Investigations are focusing on 1) refinement of the basic treatment stratagem of induction, consolidation, and maintenance; 2) expansion of risk-based, subgroup-oriented therapies; 3) assessment of minimal residual disease, its impact on disease recurrence, and its practical implications in clinical practice; 4) salvage strategies; 5) the role of stem cell transplantation in ALL; and 6) the development of new drugs based on a better understanding of disease biology.

Fusion of FIG to the receptor tyrosine kinase ROS in a glioblastoma with an interstitial del(6)(q21q21)

The transmembrane proto-oncogene receptor tyrosine kinase (RTK) ROS is an orphan receptor that is aberrantly expressed in neoplasms of the central nervous system. Here, we report the fusion of its carboxy-terminal kinase domain to the amino-terminal portion of a protein called FIG (Fused in Glioblastoma) in a human glioblastoma multiforme (GBM). By characterizing both FIG and ROS genes in normal and in U118MG GBM cells, we determined that an intra-chromosomal homozygous deletion of 240 kilobases on 6q21 is responsible for the formation of the FIG-ROS locus. The FIG-ROS transcript is encoded by 7 FIG exons and 9 ROS-derived exons. We also demonstrate that the FIG-ROS locus encodes for an in-frame fusion protein with a constitutively active kinase activity, suggesting that FIG-ROS may act as an oncogene. This is the first example of a fusion RTK protein that results from an intra-chromosomal deletion, and it represents the first fusion RTK protein isolated from a human astrocytoma.