View
53
Download
0
Category
Tags:
Preview:
DESCRIPTION
IMiDs Mechanism of Action and Future Applications. A. Keith Stewart Mayo Clinic in Arizona. Scottsdale, Arizona. Rochester, Minnesota. Jacksonville, Florida. IMiD Structures. Side effects. Potency. Potency. Identification of a Primary Target of Thalidomide Teratogenicity. - PowerPoint PPT Presentation
Citation preview
IMiDs Mechanism of Action and Future Applications
A. Keith Stewart Mayo Clinic in Arizona
Scottsdale, Arizona Rochester, Minnesota Jacksonville, Florida
IMiD Structures
PotencySide effects Potency
• Half a century ago, thalidomide was found to be teratogenic, causing multiple birth defects . . . here, we identified cereblon (CRBN) as a thalidomide-binding protein
• CRBN forms an E3 ubiquitin ligase complex with damaged DNA binding protein 1 (DDB1) and Cul4A that is important for limb outgrowth
• Thalidomide initiates its teratogenic effects by binding to CRBN and inhibiting the associated ubiquitin ligase activity
Identification of a Primary Target of Thalidomide Teratogenicity
Takumi Ito, Hideki Ando, Takayuki Suzuki, Toshihiko Ogura, Kentaro Hotta, Yoshimasa Imamura, Yuki Yamaguchi, Hiroshi Handa. Science. 2010;327:1345-50.
Cereblon
• Cereblon on chromosome 3 was first described as associated with human intelligence (Cerebral protein with Lon protease)
• Functions in the brain as an ionic channel regulator
• Highly conserved from plants to humans, broadly expressed
• Regulates AMP kinase in insulin resistance, obesity
• Forms an E3ligase complex with DDB1, Cul4A, Roc1
Cereblon Levels are Highest in MM, Leukemias, and Neuroblastoma
0
0.2
0.4
0.6
0.8
1
1.2
Via
bilit
y (%
con
trol
)
Lenalidomide
MM1.S Res
MM1.S
MM1.S MM1.S res
CRBN
b-actin
Zhu YX, et al. Blood. 2011;118:4771-9.
Lenalidomide Resistant MM Cells Lack Cereblon
<0.81 <0.9 >0.910 15 36
0
5
10
15
20
25
30
35
N =
CRBN expression as a percentage of the mean levels in all
MM
0%
19%
33%
Gene Expression Levels of Cereblon Predict Response Rate to Pomalidomide
Schuster SR, et al. Leuk Res. Jan 2014; 38(1):23-28
0 12 24 36 48 600
20
40
60
80
100
Lowest 25%Top 25%
Months
% A
live
Gene Expression Levels of Cereblon Predict Overall Survival of Pomalidomide Treated Patients
0 12 24 36 48 600
20
40
60
80
100
Lowest 25%
Months
% A
live
P=0.01 P=0.005
9.1 vs 27 months
Schuster SR, et al. Leuk Res. Jan 2014; 38(1):23-28
Zhu et al. Blood. 2014 Jun 9. [Epub ahead of print]
CRBN Binding Proteins Altered by Lenalidomide
Zhu et al. Blood. 2014 Jun 9. [Epub ahead of print]
CRBN Binding Proteins Altered by Lenalidomide
Zhu et al. Blood. 2014 Jun 9. [Epub ahead of print]
CRBN Binding Proteins Altered by Lenalidomide
IKZF1/IRF4/Myc Degradation After Lenalidomide
IKZF3
IKZF1
IRF4
MYC
b-actin
Len - + - + - + - +
Time 3h 6h 24h 48h
Degradation of Ikaros by Cereblon Binding Small Molecules
1 2 3 4 5 6 7 8 9 10 110
200
400
600
800
1000
1200
1400
1600
1800
ThalLenPom
Proteasome Inhibitors block IKAROS degradation by Lenalidomide
0 1 2 3 4 5 6 7 80
200
400
600
800
1000
1200
1400
1600
1800
0
Len (2uM)
Bortezomib Concentration (nM)
0 2.5 5 10 15 20 25 30 35 400
200
400
600
800
1000
1200
1400
1600
1800
2000
CarfilzomibCar+Len 2uM
Carfilzomib concentration: nM
8226
KMS12PE
EJM My5
SKMM
2JJN
3FR
4H112
OPM2
U266
KMS18
H929
MM
1.S
MM
1.R
KMS11
XG10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Len 2uM 5hrs
Sensitivity of MM to Lenalidomide is Correlated with IKAROS Degradation Efficiency
Most resistant cell lines Most Sensitive cell lines
• MM cell lines with adenoviral vector expressing IKAROS 1 - luciferase fusion gene. Luciferase activity was measured and normalized to cells treated with DMSO
CRBN/IZKF1/IRF4 Expression and Drug Resistance
IZKF1 L208R substitution and codon deletion mutation
XG1 MM1.S KMS11 H929 JJN3 EJM OCI-MY5 FR4 SKMM
IZKF1
IZKF3
b-actin
Len Sensitive Len Resistant
CRBN
IRF4
t(6;14) IgH-IRF4 translocation
Zhu et al. Blood. 2014 Jun 9. [Epub ahead of print]
Survival after Pomalidomide/Dexamethasone
Zhu et al. Blood. 2014 Jun 9. [Epub ahead of print]
Ikaros Expression and Pomalidomide/Dexamethasone
Overall survival 7.3 vs 27.2 months p=0.004
Lowest Quartile 0/11 Patients Responded
Zhu et al. Blood. 2014 Jun 9. [Epub ahead of print]
Tumor, 702 X, 171 mutation reads (24%)
Germline, 462 X, 0 mutation reads
IKZF3 point mutation (p.Gly157Arg)• exonic, missense, damaging
77 gene panel IKZF3 (Aiolis) Mutation: Patient Progressing on Pomalidomide and Dexamethasone
• Cereblon is the IMiD target and accumulates with IMiD binding
• Ikaros is rapidly degraded in presence of IMiD and blocked by bortezomib or carfilzomib in vitro
• Low Cereblon and Ikaros levels may predict response and survival
• Resistance can be explained in many cases by disruption of this pathway
Summary
Thank you
Recommended