Assessment of P-glycoprotein expression by immunocytochemistry and flow cytometry using two different monoclonal antibodies coupled with functional efflux analysis in 34 patients with acute myeloid leukemia.
Drug resistance often results in failure of anticancer chemotherapy in leukemias. A large number of studies have been published on the effect of P-glycoprotein (Pgp) expression on prognosis in AML. However, a consensus has been difficult to reach, due to the variable results obtained by different laboratories. Pgp expression was investigated here in bone marrow samples from 34 patients with AML including 19 newly diagnosed cases and 15 relapsing patients. Pgp expression was performed by immunocytochemistry (ICC) using the aviding-biotin-peroxydase technique with JSB1 and UIC2 MoAbs. Flow cytometry (FCM) analysis of Pgp expression was performed using UCI2 MoAbs in an indirect immunofluorescent assay without cell permeabilization. Rhodamine 123 (Rh 123) uptake was measured in the presence or absence of verapamil. Result was discordant in only 1/20 samples studied with both JSB1 and UIC2 by ICC. Results of Pgp expression were consistent on FCM and ICC in 23 of the 28 (82%) samples tested. Overall, Pgp expression was observed by ICC or FCM in 23 (67%) patients, including 11 (58%) newly diagnosed patients and 12 (80%) patients in relapse. Functional Rh123 efflux (Rh123+) was observed in 20 cases (59%): 10 de novo AML (53%) vs 10 AML in relapse (67%). The functional efflux was correlated with Pgp expression in 25 of the 34 cases analyzed (p = 0.013). 3 (9%) and 6 (18%) samples were Pgp-/Rh123+ and Pgp+/Rh123- respectively. Nine of the 14 pts (64%) treated with intensive anthracyclin-Ara C chemotherapy achieved complete remission, including 5/5 (100%) Pgp- cases vs 4/9 (44%) Pgp+ cases (p = 0.04) and 4/6 (67%) Rh 123- vs 4/7 (57%) Rh123+ cases (p = 0.5). In conclusion, assessment of Pgp expression by ICC and FMC using 2 different MoAbs coupled with functional efflux analysis confirms that Pgp expression is correlated with disease stage and response to treatment in AML. Discordant Pgp/Rh123 cases suggest a non functional Pgp or another alteration of drug transport.
Poulain
S
S
Laboratoire d'Hématologie A, Chu, Lille, France.
Lepelley
P
P
Cambier
N
N
Cosson
A
A
Fenaux
P
P
Wattel
E
E
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis* / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal; D018952:Antigens, CD34 / Q000032:analysis; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001707:Biopsy, Needle; D001854:Bone Marrow Cells / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology*; D008875:Middle Aged; D012008:Recurrence
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D018952:Antigens, CD34