Bone Marrow Findings and Possible Indices of Treatment Response afterChemotherapy and/or ATRA therapy in Acute Promyelocytic Leukemia

Kang, Yoon Hee; Park, Chan Jeoung; Chi, Hyun Sook; Lee, Kyoo Hyung; Lee, Jung Shin; Kim, Woo Kun; Kim, Sang Hee

Abstract

BACKGROUND: For acute promyelocytic leukemia (APL), NCI criteria (1990) does not provide reliable information regarding therapeutic response. We studied APL cases in our hospital and evaluated various criteria for their predictability of therapeutic response.
METHODS
Group I (GI) included 8 APL cases treated with chemotherapy and group II (GII), 10 cases with ATRA plus chemotherapy. Four treatment response indices were; (1) NCI criteria, (2) the percent sum of myelocyte and metamyelocyte (PSMM), (3) Differentiation Index[ (myelocyte+metamyelocyte+band neutrophil+segmented neutrophil)%/ (myeloblast+promyelocyte)%, DI], and (4) Maturation Index[ (metamyelocyte+band neutrophil+segmented neutrophil)%/ (myeloblast+promyelocyte+myelocyte)%, MI].
RESULTS
Among those achieving complete remission (CR), four of GI and eight of GII showed normocellularity or hypercellularity, two were in partial remission and three in persistence of GI by NCI criteria and one of GII showed persistent Auer rods at D14. Applying NCI criteria, the blast plus leukemic promyelocyte as leukemic cell were correlated well with clinical outcome. PSMM of GII were relatively constant as 20 to 29.7% at D28. DI showed wide variation and MI over 2 (Nakajima, 1996) did not correlate with CR by NCI criteria in 5 cases at D14 and 1 case at D28.
CONCLUSION
NCI criteria are the reliable predictor of CR at D28 after chemotherapy if blasts plus leukemic promyelocytes are regarded as leukemic cell while they are inappropriate at D14. The persistence of Auer rods dose not exclude CR. After ATRA plus chemotherapy therapy, PSMM over 20% at D28 may be considered as a marker for CR.