Mixed phenotype acute leukemia: A study of 61 cases using World Health Organization and European Group for the Immunological Classification of Leukaemias criteria.
OBJECTIVE
The 2008 World Health Organization (WHO) classification system grouped bilineal and biphenotypic acute leukemias together under a new heading of mixed phenotype acute leukemia (MPAL). The lineage-specific marker criteria have also changed for a diagnosis of MPAL. The goal of this study was to characterize clinical significance of this new group.


METHODS
Sixty-one patients diagnosed with MPAL using either European Group for the Immunological Classification of Leukaemias (EGIL) criteria or 2008 WHO criteria were included in this study.


RESULTS
Sixteen patients (26%) diagnosed with acute biphenotypic leukemia using EGIL criteria did not fulfill 2008 WHO criteria for MPAL. Cytogenetic data were available for 32 patients, and the most common abnormality was t(9;22) (five of 32 cases). Clinical outcome data suggested that younger patients with MPAL (≤21 years) had better overall survival (OS) in both the EGIL and WHO groups (EGIL, P = .0403; WHO, P = .0601). Compared with 177 patients with acute myeloid leukemia (AML), MPAL patients had better OS (P = .0003) and progression-free survival (P = .0001). However, no difference in OS between MPAL and 387 patients with acute lymphoblastic leukemia was present (P = .599).


CONCLUSIONS
As defined by the 2008 WHO classification, fewer patients are now classified as having MPAL than with the EGIL criteria. In this study, patients with MPAL have a better clinical outcome compared with patients with AML.
From the Boston Children's Hospital, Boston, MA; Olga.weinberg@childrens.harvard.edu.
Olga K
OK
Weinberg
Arizona Oncology, Scottsdale; and.
Mahesh
M
Seetharam
Stanford University Medical Center, Stanford, CA.
Li
L
Ren
Stanford University Medical Center, Stanford, CA.
Ash
A
Alizadeh
Stanford University Medical Center, Stanford, CA.
Daniel A
DA
Arber
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D053208:Kaplan-Meier Estimate; D015456:Leukemia, Biphenotypic, Acute / Q000145:classification* / Q000235:genetics / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D016016:Proportional Hazards Models; D014944:World Health Organization; D055815:Young Adult
Bilineal; Biphenotypic; Mixed phenotype acute leukemia