Cell surface expression of the multidrug resistance P-glycoprotein (P-170) as detected by monoclonal antibody MRK-16 in pediatric acute myeloid leukemia fails to define a poor prognostic group: a report from the Childrens Cancer Group.
Expression of the multidrug resistance (MDR-1) gene product, P-glycoprotein (P-170), and the stem cell antigen, CD34, at diagnosis were determined using monoclonal antibodies (MoAbs) MRK-16 and 12.8 respectively, in 130 pediatric acute myeloid leukemia (AML) patients entered onto Childrens Cancer Group (CCG) study CCG-2891. Fluorescein isothiocyanate (FITC) as a second step reagent was employed for the measurement of P-170 expression since it is commonly used in clinical laboratories. Nine of 30 (30%) infant ( < 1 year of age) de novo specimens expressed P-170 at levels > or = 20% of control cells. In contrast, eight of 100 (8%) AML samples from older children ( > or = 1 year of age) expressed the multidrug resistance surface protein at diagnosis. With the exception of one infant, all de novo samples that expressed P-170 also expressed CD34. Pediatric patients of any age with positive P-170 expression using MoAb MRK-16 with a FITC-conjugated second step reagent fared no worse than remaining patients treated on the same treatment with regard to induction failure, incidence of relapse, event-free survival, or overall survival. Further investigation is necessary to determine whether P-170 assay systems with greater sensitivity will distinguish pediatric AML patients with poor prognosis.
Sievers
E L
EL
Division of Pediatric Oncology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98104, USA.
Smith
F O
FO
Woods
W G
WG
Lee
J W
JW
Bleyer
W A
WA
Willman
C L
CL
Bernstein
I D
ID
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis*; D000208:Acute Disease; D018952:Antigens, CD34 / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D001853:Bone Marrow / Q000378:metabolism*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007951:Leukemia, Myeloid / Q000378:metabolism* / Q000401:mortality; D008297:Male; D011379:Prognosis; D016019:Survival Analysis
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018952:Antigens, CD34; D000954:Antigens, Surface; D014408:Biomarkers, Tumor