Plasma and cerebrospinal fluid pharmacokinetics of nelarabine in nonhuman primates.
BACKGROUND
Nelarabine is a water-soluble prodrug of the cytotoxic deoxyguanosine analog ara-G, to which it is rapidly converted in vivo by adenosine deaminase. Nelarabine has shown activity in the treatment of T-cell malignancies, especially T-cell acute lymphoblastic leukemia. Preliminary data suggested that nelarabine might penetrate into the CSF. We therefore studied the CSF penetration of nelarabine and ara-G in a nonhuman primate model that has been highly predictive of anticancer drug distribution in humans.


METHODS
Nelarabine (35 mg/kg, approximately 700 mg/m2) was administered over 1 h through a surgically implanted central venous catheter to four nonhuman primates. Blood (four animals) and ventricular CSF (three animals) samples were obtained at intervals for 24 h for determination of nelarabine concentrations, which were measured by HPLC-mass spectrometry.


RESULTS
The nelarabine plasma AUC (median+/-s.d.) was 2,820+/-1,140 microM min and the ara-G plasma AUC was 20,000+/-8,100 microM min. The terminal half-life of nelarabine in plasma was 25+/-5.2 min and clearance was 42+/-61 ml/min/kg. The terminal half-life of ara-G in plasma was 182+/-45 min. In CSF the terminal half-life of nelarabine was 77+/-28 min and of ara-G was 232+/-79 min. The AUCcsf:AUCplasma was 29+/-11% for nelarabine and 23+/-12% for ara-G.


CONCLUSIONS
The excellent CSF penetration of nelarabine and ara-G supports further study of the contribution of nelarabine to the prevention and treatment of CNS leukemia.
Berg
Stacey L
SL
Texas Children's Cancer Center, 6621 Fannin Street, MC3-3320, Houston, TX 77030, USA. sberg@txccc.org
Brueckner
Claudia
C
Nuchtern
Jed G
JG
Dauser
Robert
R
McGuffey
Leticia
L
Blaney
Susan M
SM
D000818:Animals; D000970:Antineoplastic Agents / Q000097:blood* / Q000134:cerebrospinal fluid*; D001087:Arabinonucleosides / Q000097:blood* / Q000134:cerebrospinal fluid*; D002851:Chromatography, High Pressure Liquid; D008253:Macaca mulatta; D008297:Male; D013058:Mass Spectrometry; D011355:Prodrugs / Q000493:pharmacokinetics
D000970:Antineoplastic Agents; D001087:Arabinonucleosides; D011355:Prodrugs; C028771:9-arabinofuranosylguanine; C104457:nelarabine