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588
Evaluation of the Potential Risk of QL-0A6A Induced IBIL
Increase
at Clinical Therapeutic Dose
Liang Shen1, Lijuan Hou1, Ting Zhang1, Meimei Jia1, Qiong Zhou1,
Zhengxian Gu1, Haiying He1, Xiaolin Li1, Kai Zhou1, Jian Li1,
Shuhui Chen1, Shansong Zheng2, Chunyan Sun2, Long Zhang2,
Shuyong Zhao2; 1WuXi AppTec (Shanghai) Co., Ltd, 288 FuTe
Zhong Road, Shanghai 200131, P.R. China, Shanghai, China;
2Shandong Provincial Key Laboratory of Small Molecular Targeted
Drugs, Qilu Pharmaceutical Co., Ltd. No. 243 Gong Ye Bei Road,
Jinan, Shandong Province, 250100, P.R. China, Shandong, China
Background: QL-0A6A, a novel anti-HBV agent was found to
increase total bilirubin (TBIL) and indirect bilirubin (IBIL) significantly
at doses higher than 30 mg/kg in a 28-day GLP
toxicity study in rats, while the level of direct bilirubin (DBIL)
remained almost unchanged. Although IBIL and TBIL increased
in a dose-dependent pattern, direct damage to liver cells was
not observed and comprehensive cytotoxicity studies using
HepG2.2.15 cells and rat primary cultured hepatocytes also
ruled out this possibility. Known as the major contributors,
OATP1B1 and OATP1B3 are responsible for the uptake of IBIL
into liver cells where UGT1A1 transforms IBIL into DBIL. Inhibition
of OATP1B1/1B3 and/or UGT1A1 is believed to be associated
with increased level of IBIL under normal liver function.
The aim of this study is to investigate the impact of QL-0A6A on
these transporters and enzyme and evaluate the clinical risk of
QL-0A6A at therapeutic dose. Method: 1) OATP1B1/1B3 inhibition
assay. QL-0A6A was incubated with HEK293-OATP1B1
(Estrone 3-sulfate as its substrate) or HEK293-OATP1B3 at 8
concentrations and IC50 values were determined. 2) OATP-
1B1/1B3 substrate assay. HEK293-OATP1B1, HEK293-
OATP1B3 and HEK293-MOCK cells were pre-incubated with
or without inhibitors (Cyclosporin A as the inhibitor of OATP1B1
and Ritonavir as the inhibitor of OATP1B3). After removing
the buffer, the cells were incubated with 3 concentrations of
QL-0A6A with or without the same inhibitors. The intracellular
uptake of QL-0A6A was determined by LCMS/MS and the
uptake fold and Rs/Ri ratio were calculated. 3) UGT1A1 inhibition
assay. QL-0A6A was incubated with UGT1A1 (β-Estradiol
as its substrate) and UDPGA. The formation of the metabolite
Estradiol-3-(D-glucuronide) was determined by LC-MS/MS and
IC50 values were calculated. Result: 1) OATP1B1/1B3 inhibition
assay. IC50 of QL-0A6A on OATP1B1 and OATP1B3 were
both >100 μM. 2) OATP1B1/1B3 substrate assay. The uptake
folds of QL-0A6A at 1, 10 and 100 mM by OATP1B1/1B3
were 1.17/1.15, 1.43/1.28 and 1.31/1.43 and the Rs/Ri
values were 0.706/0.840, 0.787/0.973 and 0.968/1.15,
respectively. 3) UGT1A1 inhibition assay. IC50 of QL-0A6A
on UGT1A1 was 16 μM. Conclusion: QL-0A6A was neither an
inhibitor nor a substrate of OATP1B1 and OATP1B3. It showed
weak inhibition of UGT1A1 with IC50 = 16 μM. Taking into
account of other preclinical and predicted clinical parameters,
the risk of significant increase of IBIL and its associated toxicity
in human at therapeutic dose is minimal.
Disclosures:
Zhengxian Gu - Employment: WuXi AppTec
The following people have nothing to disclose: Liang Shen, Lijuan Hou, Ting
Zhang, Meimei Jia, Qiong Zhou, Haiying He, Xiaolin Li, Kai Zhou, Jian Li, Shuhui
Chen, Shansong Zheng, Chunyan Sun, Long Zhang, Shuyong Zhao
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发表于 2016-10-12 19:47