BIIB024, a potent pan-Raf kinase inhibitor for melanoma and solid tumors
Abstract 062
Brian Elenbaas, Latika Singh, Antonio Boccia1, Patrick Cullen, Hairuo Peng, Ellen Rohde, Brian Raimundo2, Gnanasambandam Kumaravel, Ingrid Joseph1
Biogen Idec, Inc. Cambridge, MA and 1San Diego, CA; 2Sunesis Pharmaceuticals, South San Francisco, CA
Abstract
14
12
Ras/Raf
Mutation
p-ERK
Prolif.
EC50 (μM)
EC50 (μM)
A-375
Melanoma
B-Raf mt
0.065
0.24
93%
Melanoma
B-Raf mt
0.014
0.17
92%
Colo-205
Colon
B-Raf mt
0.1
1.5
81% (25 mg/kg)
HT-29
Colon
B-Raf mt
0.11
1.4
44%
Calu-6
Lung
K-Ras mt
1.0
3-10
83%
8
HCT-116
Colon
K-Ras mt
0.83
3-10
77%
BxPC-3
Pancreatic
WT Ras/Raf
0.76
3.0
73%
SK-MEL-30
4
2
Melanoma
N-Ras mt
1.1
3-10
NCI-H460
Lung
K-Ras mt
ND
NS
54%
Mia-Paca-2
Pancreatic
K-Ras mt
3-10
NS
33%
A549
Lung
K-Ras mt
NS
NS
NS
PC3
Prostate
WT Ras/Raf
NS
NS
NS
0
• B-Raf mutant cancer cell lines are the most sensitive to BIIB024 similar to
observations with MEK kinase inhibitors3
• A subset of B-Raf wild-type lines in sensitive to BIIB024
• Sensitivity of the K562 CML line may be due to Abl inhibition by BIIB024
WM-266-4 BRAFV600D mutant
human melanoma model
Tumor Volume (mm3) + SEM
24 Hr
Veh
24 hr
p-ERK
50 mg/kg
ERK
Veh
8 hr
3 Hr
8 Hr
16 Hr
24 Hr
BIIB024 25 mg/kg, PO
Dosing period: QDx21
500
5
10
15
20
25
30
35
40
45
Days Post Tumor Inoculation
• BIIB024 shows efficacy in the N-Ras mutant/B-Raf wild-type
melanoma model SK-MEL-2 at 25 mg/kg, QDx21, PO.
Efficacy in other B-Raf Wild-type Tumors
2500
BxPC-3 WT Ras/Raf human
pancreatic cancer model
2000
1500
Vehicle, PO
BIIB024 25 mg/kg, PO
1000
BIIB024 50 mg/kg, PO
Dosing period:
QDx21, 2 wks off, QDx35
500
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
Veh
24 hr
2500
2000
1500
1000
500
Dosing Period
0
p-ERK
25 mg/kg
Vehicle, PO
1000
63% (25 mg/kg)
A-375 BRAFV600E mutant
human melanoma model
2500
A. B-Raf mutant model: WM-266-4 melanoma
16 Hr
1500
Days Post Tumor Inoculation
p-ERK biomarker suppression in tumor pharmacodynamic (PD) models was measured in the indicated model and time points by
western blot analysis of tumor lysates following single oral (PO) dose of BIIB024.
Veh
16 hr
SK-MEL-30 N-Ras mutant
melanoma model
2000
0
Regression of Large B-Raf Mutant Melanoma Tumors
Tumor Pharmacodynamic Activity in
B-Raf Mutant and Wild-type Models
2500
0
• Significant efficacy observed in 10 mouse tumor xenograft models (4 B-Raf
mutant, 6 B-Raf wild-type) with daily, oral dosing
• Efficacy was not observed in 2 models where BIIB024 did not inhibit pERK or cell
proliferation (A549, PC3).
• B-Raf mutant models are generally more sensitive than B-Raf wild-type models,
consistent with the in vitro sensitivity data
• 10 μM was the highest concentration of BIIB024 tested due to low solubility
• EC50 of 6.5 μM refers to >50% inhibition at 3 μM and <50% inhibition at 10 μM
• EC50 of 15 μM refers to 20-50% inhibition at 10 μM
Dose
(50 mg/kg QD in nude or scid
mice except where noted)
WM-266-4
10
6
Tumor
Tumor Volume (mm3) + SEM
16
3000
%TGI at MTD
Model
Tumor Volume (mm 3 ) + SEM
B-RAF mutant
B-RAF non-V600E mutant
N-RAS mutant
K-RAS mutant
Ras/Raf wild-type
18
2000
2000
Tumor Volume (mm3 ) + SEM
20
Tumor Volume (mm3) + SEM
Raf/MAPK Pathway and Cancer
No significant activity at 10μM
BIIB024 EC50 (μM)
Results:
BIIB024 is a potent, oral pan-Raf kinase inhibitor that is being developed for the treatment of
melanoma and solid tumors. BIIB024 potently inhibits oncogenic B-RafV600E mutant kinase and the
wild-type B- and C-Raf kinases in biochemical assays. In a large biochemical kinase screening
panel containing 222 unique human kinases, BIIB024 inhibited a small subset of kinases in a
similar potency range as Raf kinases. To determine which cancer cell types are sensitive to
BIIB024, in vitro pERK signaling and proliferation assays were conducted in a panel of cancer cell
lines from different tumor types that differed in their Ras and Raf mutational status. BIIB024
potently inhibited signaling and proliferation in B-Raf mutant cell lines and a subset of B-Raf wildtype lines. To evaluate the ability of BIIB024 to inhibit the MAPK pathway in vivo,
pharmacodynamic studies were performed in mice bearing B-Raf mutant or wild-type tumors.
Following a single, oral dose of BIIB024 at 50 mg/kg, strong p-ERK suppression (>80%) was
observed in both B-Raf mutant and wild-type tumor models up to at least 16 hours. In tumor
xenograft efficacy studies, BIIB024 showed dose-dependent efficacy in the B-Raf mutant
melanoma model WM-266-4 with daily, oral dosing. In addition, BIIB024 caused rapid regressions
of large, established tumors in 2 B-Raf mutant models, WM-266-4 and A-375. Once dosing was
terminated, the tumors that re-grew remained sensitive to BIIB024 in a 2nd dosing cycle. BIIB024
also showed efficacy in some Ras mutant/B-Raf wild-type models, further demonstrating its in vivo
pan-Raf activity. A Phase I clinical trial of BIIB024 is planned.
Efficacy in B-Raf Wild-type Melanoma
BIIB024 Xenograft Efficacy Summary
BIIB024 In Vitro Anti-Proliferative Activity
WM-266-4
A-375
Malme-3M
K562 (BCR-ABL)
SKMEL-28
HT-29
Colo205
Lovo
Bx-PC-3
SK-MEL-2
SW620
HCT116
SK-MEL-30
MDA-MB-231
Calu-6
RKO
H1395
H2087
H1666
H1755
H460
A549
H358
HCT15
LS174T
Panc04.03
Mia-Paca-2
CFPAC1
Su86.86
Panc1
HMCB
H1650
BT474
MCF7
MDA-MB-453
MDA-MB-468
T47D
HCC38
BT549
HCC1806
PC3
Du145
Introduction:
The Raf kinases (A-Raf, B-Raf and C-Raf) are key regulators of cell proliferation and survival that
control signaling through the MAPK pathway, composed of Ras, Raf, MEK and ERK. This pathway
is frequently deregulated in cancer by mutations, leading to increased cancer cell proliferation and
survival. In particular, Ras oncogenes are mutated in 25% of all cancers and B-Raf is mutated in
7% of all cancers, including 60% of melanomas. B-Raf is an attractive therapeutic target because
most tumors with B-Raf mutations and some tumors with Ras mutations are sensitive to inhibition
of Raf or MEK in pre-clinical models. In addition, clinical efficacy has been observed in B-Raf
mutant melanomas with the PLX4032 and GSK2118436 B-Raf inhibitors.
1500
1000
500
Dosing Period
0
0 20 20
25
30
35
40
45
50
55
20 24 28 32 36 40 44 48 52 56 60 64
60
Days Post Tumor Inoculation
Days Post Tumor Inoculation
ERK
Vehicle, PO
1000
BIIB024 25 mg/kg, PO
500
Dosing period: QDx21
BIIB024 50 mg/kg, PO
0
BIIB024 50 mg/kg QDx28, PO
Vehicle PO, QDx22
Calu-6 K-Ras mutant
human NSCLC model
1500
0
5
10
15
20
25
30
35
40
45
Days Post Tumor Inoculation
BIIB024 PO, 50 mg/kg QDx35
Veh 16 hr
Raf
7.1
10.1
C-Raf wild-type
0.7
IC50 (nM)
Kinase
IC50 (nM)
Frk
1
DDR2
23
Arg
3
EphA2
28
Lck
16
Abl
34
EphA8
20
p38α
50
• BIIB024 inhibits a small subset of kinases in a similar
range as Raf kinases (IC50 1-50 nM)
Cancer cell sensitivity
Cell Line
B-Raf V600E mutant cell lines
B-Raf wild-type – sensitive (7/30 lines)
B-Raf wild-type – insensitive (23/30 lines)
pERK EC50 Range
0.01 – 0.1 μM
0.7 – 10 μM
• B-Raf mutant cell lines are the
most sensitive
• A subset of B-Raf wild-type lines
is sensitive
Tumor Volume (mm 3 ) + SEM
Kinase
• BIIB024 was screened against the Millipore
KinaseProfiler full panel screen (222 unique human
kinases) at 10 μM. Kinases most potently inhibited were
then tested at 1.0 and 0.2 μM and IC50 values were
determined on kinases most potently inhibited.
Tubulin
Conclusions
B-Raf Mutant Melanoma Tumors Remain Sensitive to a
2nd Dosing Cycle of BIIB024
Efficacy in B-Raf Mutant Melanoma
1250
Biochemical Kinase Selectivity
Screening Results
ERK
WM-266-4 BRAFV600D mutant
human melanoma model
Vehicle, PO
BIIB024 6 mg/kg, PO
BIIB024 12.5 mg/kg, PO
500
BIIB024 25 mg/kg, PO
BIIB024 50 mg/kg, PO
250
QDx14 Dosing Period
0
Dosing Period
0
5
10
15
20
25
30
are the most sensitive to BIIB024 followed by a subset of B-Raf wild-type lines
• BIIB024 shows strong and sustained p-ERK suppression in a B-Raf mutant
and two B-Raf wild-type Tumor PD models
800
600
400
200
0
Dosing Period 2
Dosing Period 1
10
20
30
40
50
60
70
80
• BIIB024 regresses large, established B-Raf mutant melanoma tumor
xenografts and tumors remain sensitive to a 2nd dosing cycle
2000
• BIIB024 is efficacious in several B-Raf wild-type tumor models
1500
• A Phase I clinical trial of BIIB024 is planned with expansion cohorts in B-Raf
mutant and wild-type melanoma patients
1000
500
References
0
90
Days Post Tumor Inoculation
Days Post Tumor Inoculation
• BIIB024 causes significant efficacy at doses ranging from 6-50 mg/kg administered
orally (PO) on a daily (QD) dosing schedule (p<0.0001 from days 11-32)
• Dose-dependent increases in exposure (AUC, Cmax) were observed in this dose
range (data not shown)
• The maximally tolerated dose (MTD) in nude mice is 50 mg/kg with QD, PO dosing
• In vitro proliferation assays demonstrate that B-Raf mutant cancer cell lines
2500
1000
0
NS
• BIIB024 is a potent pan-Raf kinase inhibitor in biochemical kinase assays
A-375 BRAFV600E mutant
human melanoma model
1200
WM-266-4 BRAFV600D mutant
human melanoma model
1000
750
• BIIB024 is efficacious in the BxPC-3 and Calu-6 B-Raf wild-type tumor
models, consistent with the sensitivity observed in the Tumor PD model
• BIIB024 regresses large, established tumors in 2 melanoma xenograft models at
50 mg/kg, QD, PO
16 hr
• BIIB024 causes strong and sustained pERK suppression (>80% to at least 16 hours
at 50 mg/kg) in the WM-266-4 B-Raf mutant model and two B-Raf wild-type models
• BIIB024 is a potent, ATP-competitive pan-Raf kinase inhibitor
• BIIB024 binds to the inactive, DFG-out conformation of B-Raf
kinase similar to sorafenib2. This binding mode differs from
the B-Raf mutant-selective inhibitor PLX4032 that binds to the
active, DFG-in conformation of B-Raf3.
IC50 (nM)
B-Raf wild-type
Veh 16 hr
pERK
Tumor Volume (mm 3 ) + SEM
Biochemical kinase activity
B-Raf mutant (V600E)
16 hr
pERK
Tumor Volume (mm 3 ) + SEM
BIIB024 Potency and Kinase Selectivity
50 mg/kg
Calu-6 lung, K-Ras MT
BxPC-3 pancreatic
B. B-Raf wild-type models:
• Pan-Raf inhibitors offer the opportunity for single agent efficacy in B-Raf
mutant and wild-type cancers, including Ras mutant cancers1
BIIB024 50 mg/kg, PO
Dosing period #1, QDx14 (days 8-21)
Regrowth, no drug (days 22-54)
Dosing period #2, QDx28 (days 55-82)
Re-Dosing Periods
Dosing Period
0
10
20
30
40
50
60
70
80
90
Days Post Tumor Inoculation
1. Heidorn, S. J. et al. (2010) Cell 140, 209-221.
2. Wan, P. T. et al. (2004) Cell 116, 855-867.
Vehicle QDx14, PO (days 13-27)
BIIB024 50 mg/kg, PO QDx28 (days 34-62)
3. Bollag, G. et al. (2010) Nature 467, 596-599.
4. Solit, D. B. et al. (2006) Nature 439, 358-362.
BIIB024 50mg/kg, QDx14 (days 13-27)
Regrowth, no drug (days 28-63)
BIIB024 50 mg/kg, QDx28 (days 63-91)
EORTC-NCI-AACR Molecular Targets and Cancer Therapeutics
November 16-19, 2010