thor-707: an engineered il-2 for the treatment of solid tumors … · 2019-04-19 · ex vivo...
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Marcos E. Milla; Jerod L. Ptacin; Carolina E. Caffaro; Hans R. Aerni; Lina Ma; Kristine M. San Jose; Michael J. Pena; Robert W. Herman;
with superior pre-clinical efficacy and safety evidenceTHOR-707: An engineered IL-2 for the treatment of solid tumors
Yelena Pavlova; David B. Chen; Laura K. Shawver; Lilia K. Koriazova; Ingrid B. Joseph. Synthorx Inc. La Jolla, CA
mmilla@synthorx.com
Binding Affinity of THOR-707 to Human L-2 Receptor aand b Chains
0 . 0 0 0 1 0 . 0 1 1 1 0 0
0
4 0 0 0
8 0 0 0
1 2 0 0 0
1 6 0 0 0
0 . 0 0 0 1 0 . 0 1 1 1 0 0
0
3 0 0 0
6 0 0 0
9 0 0 0
1 2 0 0 0
THOR-707 Pharmacokinetics and In Vivo Activation of Mouse and
Non-human Primate (NHP) CD8+ T Cells
• Stable pegylation confers to THOR-707 high plasma AUC in both
NHP and mouse
• Full PD effect on peripheral CD8+ T cell IL-2R proximal activation
marker pSTAT5, and early proliferation marker Ki67
THOR-707 Single IV Dosing in Mouse: Induction of Peripheral
CD8+ T and NK Cell Extravasation and Expansion
0 .0 0 .5 1 .0
0
2 0
4 0
6 0
8 0
1 0 0
5 1 0 1 5 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 1 3 0
T im e (h )
pS
TA
T5
+%
in
CD
8+
T c
ell
s
V e h ic le
A ld e s le u k in
T H O R -7 0 7
THOR-707: long PD
effect due to longer
half-life
Protein EC50 nM
IL-2 0.0022
THOR-707 1.95
Protein EC50 nM
IL-2 1.47
THOR-707 5.71
0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0 1 6 0
0 .1
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
T im e (h )
TH
OR
-70
7 (
ng
/ml)
M o u s e
C y n o m o lg u s
0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0
0
1 0
2 0
3 0
4 0
5 0
T im e (h )
NK
%
V e h ic le
T H O R -7 0 7
• THOR-707 does not engage IL-2R a chain yet binds the b chain
similarly to IL-2
• As expected for a not-alpha IL-2, THOR-707 activates with similar
potency the IL-2R abg and bg complexes in human primary T cells
Agent / PK speciesDose
mg/kgAUC0-t
ng*h/mLt1/2
hCD8+ pSTAT5
%
Aldesleukin mouse 0.3 432 0.576 80%
THOR-707 mouse 0.3 45600 13.3 100%
THOR-707 NHP 0.3 76,100 11.0 100%
0 2 8 1 2 2 4 4 8 7 2 1 2 0
0
2 0
4 0
6 0
8 0
Tre
g%
in
CD
3+
T
V e h ic le
T H O R -7 0 7
T im e (h )
THOR-707 Activation of Human CD4+ Tregand CD8+ TeffCells
Ex vivo (pSTAT5)
Human IL-2 Pharmacology is Comparable Between Human and
NHP, but not Between Human and Mouse IL-2R
• Binding studies show that human IL-2 has similar affinity for the human and
Cynomolgus IL-2R β chains. No detectable binding to the mouse b chain
• Cell-based studies (pSTAT5) show that human IL-2 potency depends on the
cell type:
▪ Comparable potency across species for Treg cells expressing IL-2 abg chain
complexes
▪ Dramatic drop in potency at mouse CD8+ T cells relative to human (75x) and NHP
(154x)
• CD8+ T cells are the target cell for the anti-tumor pharmacological effect of IL-
2. Therefore, THOR-707 is dosed in mice at relatively high levels, to
compensate for IL-2’s decreased potency at the mouse IL-2 receptor b chain
THOR-707 Induces Durable CD8+ T Cell Infiltration in Mouse
B16F10 Tumors
THOR-707 Shows Dose-dependent Single Agent
Efficacy in CT-26 Tumor-bearing Mice
Da
y 0
Da
y 1
Da
y 2
Da
y 3
Da
y 5
Da
y 7
Da
y 1
0
0
2 0
4 0
6 0
CD
8+
% in
C
D3
+T
V e h i c l e
3 m g / k g
P r e - d o s e
* * * * * *
0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0 2 2 2 4
0
2 0 0
4 0 0
6 0 0
8 0 0
1 0 0 0
D a y s
Me
an
tu
mo
r v
olu
me
(m
m3
S
EM
)
Many regressions
observed in THOR-707
+ anti mPD-1 treated
mice
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0
0 . 0 1
0 . 1
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
1 0 0 0 0 0
0 . 0 1
0 . 1
1
1 0
1 0 0
1 0 0 0
1 0 0 0 0
1 0 0 0 0 0
T i m e ( h )
Pla
sm
a P
K (
ng
/m
L)
Tu
mo
r/S
ple
en
P
K (
ng
/g
)
3 m g / k g T u m o r
3 m g / k g P l a s m a
3 m g / k g S p l e e n
707A tumor half-life was ~2X plasma half life (24.6 vs 12.6 h): Synthorin
penetrates the tumor compartment and is retained there
Based on AUC, 8% of plasma levels are in the tumor (spleen: 3.6%):
increased tumor distribution
THOR-707 Shows Increased Distribution and Retention in
C57Bl6 Mouse B16F10 Tumors
Binding KD (SPR) nM IL-2R EC50 (pSTAT5) pg/mL
Species IL-2Ra IL-2Rb CD4+ Treg Cell CD8+ T Cell
Human 1.71 360 6.50 4,884
NHP 2.90 270 9.15 2,372
Mouse 23.5 N.D.A 12.7 366,276
A: No detectable binding
C: Concentration-response curves lack upper baseline
THOR-707: A Reprogrammed IL-2 That Expands Lymphocytes
Without Inducing Eosinophil Proliferation
THOR-707 Single Dose
Leukocyte Subpopulations0.3 mg/kg IV
THOR-707 Single Dose
Leukocyte Expansion 0.1 or 0.3 mg/kg IV
Unlike aldesleukin, THOR-707 Shows Strong Bias for Expanding
Tumor-Fighting Lymphocytes vs. Eosinophils Responsible for VLS;
no increase in lung weights up to 1 mg/kg
Repeat Dosing of THOR-707 in NHP Elevated CD8+ T Cells in the
Lymphocyte Population and Achieved Ki67 Expression (≥60%)
Peripheral CD8+ Teff Cell Activation and Proliferation
Peripheral CD8+ Teff Cells Ki67 Expression
Summary
-1 1 2 3 4 5 6 7 8 910
11
12
13
14
15
16
17
18
19
20
21
0
1 0
2 0
3 0
4 0
D a y s
ce
ll c
ou
nts
x1
03/
L
w h ite b lo o d c e lls
d o se
ly m p h o c y te s
e o s in o p h ils
-1 2 4 6 8
10
12
14
16
18
20
0
1 0
2 0
3 0
4 0
D a y s
x1
03
/
L
0 . 1 m g / k g I V
d o s e
0 . 3 m g / k g I V
• At the approved clinical dose
(0.037 mg/kg), aldesleukin (IL-
2) induces eosinophilia
concomitantly with lymphocyte
proliferation, leading to
vascular leak syndrome, a fatal
adverse event
At Doses Leading to Maximal PD, THOR-707 Expands Lymphocytes
Without Eosinophilia in NHP
• Synthorx Expanded Genetic Alphabet technology platform was applied to the
discovery of THOR-707, an engineered form of IL-2 with a stable, covalent PEG
bioconjugate at a single, targeted position
• THOR-707 displays a “not-alpha” pharmacological profile: it activates the IL-2R bg
complex of CD8+ T effector and NK cells with similar potency to IL-2. In contrast,
because of its lack of a chain engagement, THOR-707 does not have a high bias
for activation of the IL-2R abg complex of CD4+ regulatory T cells
• THOR-707 exhibits extended half-life and high AUC in both mouse and NHP,
resulting in IL-2R occupancy levels that drive maximal activation and proliferation of
CD8+ effector and memory cells, and NK cells, with little or no expansion of CD4+
T regulatory cells
• THOR-707 elicits durable infiltration of CD8+ T cells into CT-26 syngeneic mouse
tumors. In this model, it displays dose-dependent single efficacy in those tumors,
and additivity in combination with a PD-1 checkpoint inhibitor
• In NHP, maximal peripheral CD8+ T cell proliferation is observed at 0.1 mg/kg: the
same level and durability of expansion is seen at the 0.3 and 1 mg/kg dose levels.
For that, Ki67 induction must reach 60% of CD8+ T cells or above
• No eosinophilia or vascular leak syndrome was observed at any dose level. This
confirms that THOR-707 can be dosed at levels eliciting full pharmacodynamic
responses without VLS, a serious adverse event previously associated with
aldesleukin
-1 1 2 3 4 5 6 7 8 9
10
11
12
13
14
15
16
17
18
19
20
21
22
0
2 0
4 0
6 0
8 0
1 0 0
D a y s
Ki6
7+
% in
C
D8
+T
c
ell
s
d o s e
V e h i c l e
0 . 0 3 m g / k g
0 . 3 m g / k g
0 . 1 m g / k g
d o s e d o s e
1 m g / k g
-1 1 2 3 4 5 6 7 8 9
10
11
12
13
14
15
16
17
18
19
20
21
22
0
2 0
4 0
6 0
D a y s
CD
8+
% in
s
in
gle
ts
V e h i c l e
0 . 0 3 m g / k g
0 . 3 m g / k g
0 . 1 m g / k g
d o s e d o s e d o s e
1 m g / k g
Design Strategy for Not-alpha THOR-707 IL-2
IL-2 binds to the IL-2
receptor αβγ complex at
high affinity because of
the α chain
Targeted pegylation of
THOR-707 at the novel
amino acid blocks α
chain binding
• Improved Selectivity - Reduced CD4+ Treg bias with retained
stimulatory activity of CD8+ T and NK cells in preclinical studies
• Increased Therapeutic Index – No induction of vascular leak syndrome
in Cynomolgus non-human primate (NHP) up to 1 mg/kg
• Convenient dosing schedule - Expected Q2W dosing or less frequent
• Reduced Risk of Immunogenicity - Covalent attachment of stable,
“shielding” PEG; conjugation site devoid of MHC-II anchors
Single, stable PEG covalently attached to a novel amino acid site to
make a “not-alpha” IL-2 protein
Background
Screening: SAR for THOR-707 “Not-Alpha” IL-2 Synthorin
IL-2
IL-2Rb IL-2Rg
IL-2 drives Rbg
dimer formation
• IL-2/IL-2Ra crystallographic interface examined to identify potential sites
for bioconjugation
• Pegylated variants tested via DiscoveRx PathHunter™ assay (IL-2R bg or
abg recombinant U2OS cells)
• Identified three sites with not a IL-2R bg/abg profile. THOR-707 selected
based on expression yield
CD8+ T Cells Memory CD8+ T Cells
NK Cells CD4+ Treg Cells
• THOR-707 drives CD8+ tumor infiltration comparable to levels observed with a combination of CTLA-4 and PD-1 checkpoint inhibitor mAbs in this syngeneic melanoma tumor model*
• In contrast, THOR707 does not change over time Treg infiltration
*Curran MA et al (2010) PNAS 107: 4275
Day 2
Day 3
Day 5
Day 7
Day 1
0
0
2 0
4 0
6 0
Tre
g%
in
CD
3+
T
V e h ic le
3 m g /k g T H O R -7 0 7
T re g c e lls fro m D a y 0 s a m p le s w e re to o fe w to b e p lo tte d
IL-2 Synthorinbg
EC50 nM
abg
EC50 nMbg/abg ratio
IL-2 1.68 0.0740 23
Best possible 1.68 1.68 1
THOR-700 3.00 1.50 2
THOR-701 6.75 0.150 45
THOR-702 9.84 0.131 75
THOR-703 4.16 0.165 25
THOR-704 6.37 0.0489 130
THOR-705 6.09 0.515 12
THOR-706 7.70 0.08925 86
THOR-707 23.8 4.44 5
THOR-708 9.06 0.110 83
THOR-709 9.99 0.0830 121
IL-2 Dual Pharmacology Prevents Aldesleukin from Dosing for Maximal
CD8+ T cell Expansion
• IL-2 binds to two different receptor forms:
• At high affinity, it engages the IL-2 receptor (IL-2R) abg complex expressed on CD4+ immune suppressive regulatory T cells (Tregs).
• The IL-2R abg complex is also expressed on type 2 innate lymphoid cells and eosinophils. These cells mediate vascular leak syndrome (VLS), a severe clinical adverse event of IL-2 leading to hypotension, pulmonary edema, and liver and kidney shock
• At lower affinity, it engages the IL-2R bg complex expressed on CD8+ T and natural killer (NK) cells. These cells are critical for anti-tumor responses
• We sought to design an IL-2 drug with wild type affinity for the IL-2R bg complex yet no engagement of the a chain
Meyers FJ et al (1991) Clin. Pharmacol.
Ther. 49: 307
0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
T re a tm e n t g ro u p s Q W x 3 IV
Tu
mo
r V
olu
me
(m
m3)
S
EM
* * * p < = 0 .0 0 1
Ve
hic
le
1 m
g/k
g
3 m
g/k
g
6 m
g/k
g
9 m
g/k
g
* * *
* * *
* * *
Day 17 Tumor Size Measurements
THOR-707 Shows Additive Efficacy with an Anti-PD-1
mAb in CT-26 Tumor-bearing Mice
• A single 0.3 mg/kg IV dose of THOR-707 induces the extravasation and expansion of CD8+ T cells, including memory cells. They are critical for tumor attack.
• THOR-707 also expands peripheral NK cells
• THOR-707 did not stimulate peripheral CD4+ Treg proliferation
7 2 9 6 1 2 0
0
1 0
2 0
3 0
4 0
T im e (h )
me
mo
ry C
D8
+ T
eff
% i
n C
D3
+T
V e h ic le
T H O R -7 0 7
0 2 0 4 0 6 0 8 0 1 0 0 1 2 0
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
T im e (h )
CD
8+
% i
n C
D3
+T
V e h ic le
T H O R -7 0 7
Day 14 Tumor Size Measurements
CD4+ Treg CD8+ Teff
pS
TA
T5
MF
I
nM cytokine
pS
TA
T5
MF
I
nM cytokine
0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
5 0 0 0
Tu
mo
r V
olu
me
(m
m3
)
SE
M
v e h ic le (Q W x 3 + is o ty p e c o n tro l
1 0 m g /k g , B IW x 3
T H O R -7 0 7 (6 m g /k g - Q W x 3 , iv )
A n t i P D -1 (1 0 m g /k g - B IW x 3 , ip )
T H O R -7 0 7 (6 m g /k g - Q W x 3 , iv ) +
a n t i P D -1 (1 0 m g /k g , B IW x 3 , ip )3 5 .6 %
4 4 .1 %
7 4 .6 %
* *
* * *
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