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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Adolescent, Adult, Aged, CD56 Antigen, Clinical Trials as Topic, Drug Resistance, Neoplasm, Female, Humans, Male, Middle Aged, Phenotype, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma, Prognosis, Remission Induction, Survival Analysis, Young Adult.
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Is cD56 expression in T-cell acute lymphoblastic leukemia associated with non-thymic phenotype and resistance to induction therapy but no inferior survival after risk-adapted therapy? Context: Expression of CD56 has been associated with poor prognosis in acute myeloid leukemia and aggressive lymphoma. We analyzed the impact of CD56 expression in a cohort of 452 newly diagnosed adult T-cell acute lymphoblastic leukemia (T-ALL) patients; clinical data were available for 306 patients. Treatment was according to the GMALL study protocols 06/99 and 07/03 stipulating stratification into standard (thymic T-ALL) and high risk (pre- and mature T-ALL) groups. CD56 expression was detected in 63/452 (13.9%) patients. CD56(+) T-ALL were predominantly of non-thymic (pre-T 35%, mature 41%) immunophenotypic subtypes, whereas 53% of the CD56(-) cases were thymic T-ALL (p=0.00002). CD13, CD33, CD34 and HLA-DR were significantly more frequently expressed. A clonal T-cell receptor rearrangement was detected in 22/23 CD56(+) ALL. No major clinical differences were observed at presentation. Treatment of CD56(+) ALL resulted in a lower rate of complete remissions (70% vs. 88%) (p=0.001) and a higher rate of resistant disease (21% vs. 8%) (p=0.004). CD56 expression had no significant influence on overall (48% vs. 59%) and disease free survival (67% vs. 57%) at three years.
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CD56 is expressed on a subset of adult T-ALL with distinct immunophenotypical features and higher resistance to therapy. Most CD56(+) ALL were treated in the high-risk arm of the GMALL study protocols owing to their non-thymic phenotype. Thus after risk adapted treatment a prognostic impact of CD56 expression was not detectable. Final Decision: yes