High expression of the very late antigen-4 integrin independently predicts reduced risk of relapse and improved outcome in pediatric acute myeloid leukemia: a report from the children's oncology group.
OBJECTIVE
To evaluate the prognostic significance of the integrin cell adhesion molecule very late antigen-4 (VLA-4) in acute myeloid leukemia (AML).


METHODS
We prospectively quantified VLA-4 expression in 216 patients enrolled onto COG-AAML03P1 by flow cytometry and correlated expression levels with disease characteristics and clinical outcome.


RESULTS
VLA-4 mean fluorescence intensity (MFI) varied 35-fold (range, 30 to 1,110; median, 219.5). High VLA-4 expression (> median MFI), compared with low expression, was associated with younger age (7.1 v 12.1 years, respectively; P < .001), lower FLT3 internal tandem duplication prevalence (4% v 21%, respectively; P < .001), and higher likelihood of extramedullary disease (16% v 5%, respectively; P = .013). In low- and high-expression groups, rates of remission (89% v 80%, respectively; P = .137) and minimal residual disease (29% v 25%, respectively; P = .700) were similar. Patients with low VLA-4 expression, compared with high expression, had a higher relapse rate (RR; 44% +/- 10% v 24% +/- 9%, respectively; P = .011) and lower disease-free survival (DFS; 48% +/- 11% v 67% +/- 10%, respectively; P = .023) after 3 years. Multivariate analyses showed that low VLA-4 expression was an independent adverse prognostic factor for DFS (hazard ratio [HR] = 1.98; P = .038) and RR (HR = 2.77; P = .009). Subgroup analyses indicated that the prognostic role of VLA-4 expression was most prominent in patients with standard-risk AML, in whom low VLA-4 expression was associated with inferior DFS (34% +/- 16% v 69% +/- 14% for high expression; P = .011) and higher RR (61% +/- 16% v 26% +/- 14% for high expression; P = .009). A similar trend was seen in low-risk but not high-risk patients.


CONCLUSIONS
High VLA-4 expression is associated with better clinical outcome in pediatric AML and is an independent predictor of relapse that may refine our abilities to stratify patients without identifiable cytogenetic or molecular risk factors.
Walter
Roland B
RB
Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, D2-190, Seattle, WA 98109-1024, USA. rwalter@fhcrc.org
Alonzo
Todd A
TA
Gerbing
Robert B
RB
Ho
Phoenix A
PA
Smith
Franklin O
FO
Raimondi
Susana C
SC
Hirsch
Betsy A
BA
Gamis
Alan S
AS
Franklin
Janet L
JL
Hurwitz
Craig A
CA
Loken
Michael R
MR
Meshinchi
Soheil
S
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D017326:Clinical Trials, Phase III as Topic; D015331:Cohort Studies; D005434:Flow Cytometry; D006801:Humans; D007223:Infant; D039041:Integrin alpha4beta1 / Q000096:biosynthesis*; D015470:Leukemia, Myeloid, Acute / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D016896:Treatment Outcome; D055815:Young Adult
D039041:Integrin alpha4beta1