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
Sievers, E.L.; Smith, F.O.; Woods, W.G.; Lee, J.W.; Bleyer, W.A.; Willman, C.L.; Bernstein, I.D.
Leukemia 9(12): 2042-2048
1995
ISSN/ISBN: 0887-6924 PMID: 8609715 Document Number: 454207
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 Children's 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 ( lt 1 year of age) de novo specimens expressed P-170 at levels gtoreq 20% of control cells. In contrast, eight of 100 (8%) AML samples from older children ( gtoreq 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.