Incidence and clinical relevance of myeloid antigen-positive acute lymphoblastic leukemia

Flowcytometric comparative analysis in acute leukemias between Indian and proposed minimal screening panel

BACKGROUND

Acute myeloid leukemia and acute lymphoid leukemia differ substantially in response to therapy and course, and accurate differentiation of the two is fundamental to therapeutic decisions. Immunophenotyping is used for this purpose, and various guidelines have been proposed regarding a minimal screening antibody panel. Most of them have been found inefficient.

METHODS

Eighty-two cases of consecutive acute leukemias reporting to this hospital over a period of two years were included in the study. Peripheral blood smear, bone marrow aspirate, and bone marrow biopsy were studied using morphology, cytochemical stains, and relevant immunohistochemical stains on selected biopsy specimens. Flowcytometry analysis was carried out using Indian consensus screening panel and our proposed minimal screening panel (PMSP) for comparison.

RESULT

Immunophenotyping using PMSP resulted in 95.12% accurate diagnosis versus Indian consensus minimal screening panel (ICMSP) with an accuracy of 92.68%. This result was statistically significant as per Chi Square tests.

CONCLUSION

PMSP can be used as a substitute for ICMSP, since it includes lineage-specific cytoplasmic antibodies, as well as lesser number of monoclonal antibodies, and enables us to diagnose mixed lineage leukemia. Fewer markers can be linked to a lower cost as well, which is relevant in a developing economy.

Emerging drugs for adult acute lymphoblastic leukaemia

Although most patients with adult acute lymphoblastic leukaemia (ALL) can achieve a remission when treated with conventional, DNA-damaging chemotherapy, in more than half of all cases the disease relapses and ultimately results in death. Therefore, there is a substantial need for new antileukaemic drugs. Recent advances in the understanding of the molecular alterations in ALL have lead to the identification of new targets and the arrival of molecular-targeted therapies in the clinical setting. The prototype for this approach is the treatment of Philadelphia chromosome-positive ALL with imatinib mesylate. Here, the targeting of a molecular abnormality--inhibition of BCR-ABL tyrosine kinase--has turned a very poor-prognosis disease into one in which promising results are achieved. Promising new therapies are under development that target various goals, including the NOTCH signalling pathway, purine nucleoside phosphorylase activity, mammalian target of rapamycin and tyrosine kinase. This review outlines recent advances in the development of emerging drugs for the treatment of adult ALL. The recent advances in the understanding of the biology and pathogenesis of ALL have helped to determine prognosis and to plan the therapy of adult patients with ALL. Still, despite improved complete remission rates of 65-90% with current therapy, only 20-40% of patients can be considered cured. New therapeutic alternatives are needed to improve these results. With a better understanding of the disease, more target-specific therapies could be designed. The aim of this review is to highlight new pharmacotherapies and those emerging drug treatments for patients with adult ALL.

The prognostic significance of antigen expression in leukaemia

Numerous immunophenotypic features have been examined for their potential prognostic significance in predicting treatment outcome in leukaemias. These include immunophenotypic subgroups of acute lymphoblastic leukaemia (ALL) and immature acute myeloid leukaemia, expression of individual surface antigens or combined immunophenotypic features, and more recently, molecules mediating the multidrug resistance phenotype or being involved in the regulation of drug-induced apoptosis. Most previous studies investigating the prognostic significance of antigen expression in leukaemia have not used the information provided by multiparameter flow cytometry and have chosen rather arbitrary cut-off points for marker positivity. Moreover, given significant associations between immunophenotypic features and genetic abnormalities in leukaemic cells, immunophenotyping as an independent predictor of treatment outcome has been questioned. Thus, except for lineage assignment of leukaemic blasts and definition of maturational status in ALL, information provided by immunophenotyping is currently not applied to risk-classification systems or used for planning patient treatment in leukaemia. We review some of the recent findings regarding the prognostic impact of distinct immunophenotypic features in acute leukaemias and myelodysplastic syndrome.

Prognostic factors in adult acute lymphoblastic leukemia

The prognosis of patients with acute lymphoblastic leukemia (ALL), treated with modern chemotherapeutic regimens, is dependent on a number of variables. The major prognostic factors for survival in adult ALL are age, cytogenetic abnormalities, immunologic subtype, white blood cell (WBC) count, and time to achieve complete remission (CR). Determination of these factors is crucial for adapting post remission therapy in adult ALL. Indeed, risk-adapted strategies based on those biologic and clinical features are currently being applied to improve survival. In this review, we report the different prognostic factors described in adult ALL and discuss the controversies in current adult ALL management in relation with these different features. The data reported are derived from the medical literature and from the experience of the authors. Prognostic factors appear to be time-dependent. This emphasizes their determination according to the phase of treatment. The use of time-segmented multivariate analysis able to distinguish prognostic factors associated with the induction phase and those associated with the post-induction phase of treatment seems suitable to define accurately prognostic models.