INITIAL P-GLYCOPROTEIN EXPRESSION IN CHILDHOOD ACUTE LYMPHOBLASTIC LEUKEMIA: NO EVIDENCE OF PROGNOSTIC IMPACT IN FOLLOW-UP |
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| Authors: | Jukka Kanerva Maarit I. Tiirikainen Anne Mäkipernaa Pekka Riikonen Merja Möttönen Toivo T. Salmi |
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| Affiliation: | 1. Hospital for Children and Adolescents, Helsinki University Central Hospital, Helsinki, Finland.;2. UCSF Cancer Center, University of California at San Francisco, San Francisco, California, USA.;3. Department of Pediatrics, Tampere University Hospital, Tampere, Finland.;4. Department of Pediatrics, Kuopio University Hospital, Kuopio, Finland.;5. Department of Pediatrics, Oulu University Hospital, Oulu, Finland.;6. Department of Pediatrics, Turku University Central Hospital, Turku, Finland. |
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| Abstract: | Treatment results in childhood acute lymphoblastic leukemia (ALL) have improved remarkably during the past 20 years, but still 25% of children cannot be permanently cured. Drug resistance is a major cause of poor outcome. One of the most investigated resistance mechanisms is the P-glycoprotein (P-gp)-mediated multiple-drug resistance (MDR). The authors prospectively analyzed P-gp using flow cytometry with monoclonal antibody JSB1 in a population-based series of 103 children with ALL treated according to intensive Nordic ALL protocols. Increased P-gp expression was detected in 55 patients (53%). With a cutoff value of 1% P-gp-positive blasts in bone marrow, no difference was found in event-free survival (EFS) or overall survival between children with low vs. increased P-gp expression. The 4-year EFS in the whole series was 77%. Patients with T-ALL had higher P-gp levels than the others, 3.6% vs. 1.0% (p = .002). P-gp expression did not correlate with the white blood cell count, age, sex, or cytogenetics. The authors conclude that the level of P-gp expression cannot be used as a tool for treatment stratification in childhood ALL. |
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| Keywords: | Childhood Leukemia Multiple-DRUG Resistance P-GLYCOPROTEIN |
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