BIOLOGIC AND CLINICAL-SIGNIFICANCE OF CD7 EXPRESSION IN ACUTE MYELOID-LEUKEMIA

CD7 antigen, a T-cell lineage associated antigen, is expressed in a mi nority of patients with acute myeloid leukemia (AML). The biologic and clinical significance of this finding is not clearly established. In this retrospective study of patients with de novo acute myeloid leukem ia, we have identified CD7 expression and analyzed its association wit h markers expressed early in hemopoietic ontogeny and clinical paramet ers. Among 60 consecutive AML patients, we found six (10%) expressing CD7 on leukemic cells. There were five males and one female and the me an age was 59.6 years (age range: 32-76 years) with no demographic pec uliarities. The FAB subtypes were: M0 (2), M1 (1), M2 (1), and M4 (2), CD7 expression was associated with immature antigens CD34, HLA-DR, an d terminal deoxynucleotidyl transferase (TdT) and antigen receptor gen e rearrangements (rearrangements of T-cell receptor gamma chain in 6/6 and immunoglobulin heavy chain in 2/6). Hepatomegaly was present in t hree and this was associated with splenomegaly with lymphadenopathy in one patient. Mediastinal or central nervous system Involvement was ab sent. Complete remission was achieved in two patients with standard ch emotherapy; one of these is in remission and alive (5 years later), wh ile one died following relapse 9 months later. Three patients had sign ificantly lower response to standard therapeutic regimen (two died dur ing induction and one died 7 months later without ever achieving compl ete remission). One patient has been excluded in determining the progn ostic significance of CD7 due to early death. Our results suggest orig in of CD7+ AML from early hemopoietic precursors and indicate biologic aggressiveness in a significant proportion of patients. We suggest ev aluation of CD7 in all patients with AML at the time of diagnosis in v iew of poor clinical outcome. (C) 1998 Wiley-Liss, Inc.