Relationship between elevated levels of the alpha 1 acid glycoprotein in chronic myelogenous leukemia in blast crisis and pharmacological resistance to imatinib (Gleevec) in vitro and in vivo.
The Abl tyrosine kinase inhibitor imatinb is becoming a standard for the treatment of chronic myelogenous leukemia (CML). However, Bcr-Abl gene mutations have been reported mainly in relapsing or resistant patients. In primary resistant patients, only few mutations have been documented so far, suggesting alternative mechanisms. We aimed to investigate if alpha 1 acid glycoprotein (AGP), an acute phase drug binding protein, could be a biological marker for pharmacological resistance to imatinib in nine patients in acute phase CML. All patients (3/3) with high AGP dosages (2.31+/-0.17 mg/mL; normal values, 0.5-1.3mg/mL) were primary resistant to imatinib whereas an early clinical response was observed for the six patients with normal AGP levels (1.13+/-0.2mg/mL). No mutation in the adenosine triphosphate domain of Abl were detected before the initiation of imatinib therapy. By using in vitro tests combining various imatinib concentrations (1-10 microM) with purified human AGP (1 and 3 mg/mL), we demonstrate that imatinib-induced apoptosis of K562 or fresh leukemic CML cells is abrogated or reduced. The same effect was observed using sera from donors with high AGP levels (1.9-3.28 mg/mL). In patients with CML in blastic phase, AGP levels could reflect pharmacological resistance to imatinib, suggesting that increased dosage of imatinib or the use of a competitor to drug binding should be recommended to optimize the therapeutic effect of the drug.
Laboratoire de Biologie Cellulaire Hématopoïétique, EMI 00-03, Hôpital Saint-Louis, 75010 Paris, France.
Jérôme
J
Larghero
Thibaut
T
Leguay
Samia
S
Mourah
Isabelle
I
Madelaine-Chambrin
Anne Laure
AL
Taksin
Emmanuel
E
Raffoux
Jean Noel
JN
Bastie
Laurent
L
Degos
Patrice
P
Berthaud
Jean Pierre
JP
Marolleau
Fabien
F
Calvo
Christine
C
Chomienne
François Xavier
FX
Mahon
Philippe
P
Rousselot
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001549:Benzamides; D001752:Blast Crisis / Q000378:metabolism / Q000473:pathology*; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology; D009961:Orosomucoid / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D001549:Benzamides; D009961:Orosomucoid; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate