Science - USA (2020-08-21)

(Antfer) #1

monomers are positioned to form hydrogen-
bond interactions with both the carboxylic
acid of one bound molecule of SR-717 and the
amide carbonyl of the other bound SR-717


molecule (Fig. 2D and fig. S9B). These side
chains, at the base of the cGAMP binding site,
form hydrogen-bonding interactions with the
purine bases of bound cGAMP (PDB ID 4KSY).

Consistent with the observed requisite of a
carboxylic acid for binding (fig. S2E), the car-
boxylic acid of each molecule of bound SR-717
is directly positioned in the location of a

Chinet al.,Science 369 , 993–999 (2020) 21 August 2020 4of7


B16F.10 (5e^5 cells)
Day 1

Day 11
Treat daily for 7 days
30 mg / kg I.P.

C

5 mg/kg15 mg/kg30 mg/kg

0

100

200

300

400

500

600
A B

IFN-

β (pg/mL)

IFN-β
IL-6

Cytokine (pg/mL)
0

200

400

600

800

1000

1200

Vehicle SR-717 Vehicle SR-717
WT Stinggt/gt

Vehicle SR-717 DMXAA

0

30

60

90

120

150

# of nodules / set of lungs

**
n.d.

Time post B16.F10 injection (days)

15 18 21 24 27 30

0

25

50

75

100

Time post B16.F10 injection (days)

Survival (%)

WT + vehicle
WT + SR-717
Stinggt/gt + vehicle
Stinggt/gt +SR-717

WT + vehicle
WT + SR-717
Stinggt/gt +vehicle
Stinggt/gt + SR-717

D E F

Vehicle
SR-717
Anti-PD-1
Anti-PD-1 + SR-717

G H I

Vehicle
SR-717
Anti-PD-L1
Anti-PD-L1 + SR-717

JK

10 15 20 25 30 35

0

25

50

75

100

Survival (%)

Vehicle
SR-717
Anti-PD-L1
Anti-PD-L1 + SR-717

10 15 20 25 30 35

0

25

50

75

100

Survival (%)

Vehicle
SR-717
Anti-PD-1
Anti-PD-1 + SR-717

Vehicle

SR-717

DMXAA

10 12 14 16 18 20
0

500

1000

1500

2000

2500

Tumor volume (mm

3 )

Treatment

10 12 14 16 18 20

0

300

600

900

1200

1500

Time post B16.F10 injection (days)

Tumor volume (mm

3 )

Time post B16.F10 injection (days)

Time post B16.F10 injection (days)

10 12 14 16 18 20

0

300

600

900

1200

1500

Time post B16.F10 injection (days)

Tumor volume (mm

3 )

Fig. 3. STING-dependent pharmacodynamic and antitumor activities of
systemic SR-717.(A) Dose escalation of SR-717 by intraperitoneal injection and
corresponding plasma IFN-blevels in C57BL/6 mice (n= 4) 4 hours after dosing,
after 4 days of daily dosing (n= 4). (B) Plasma concentrations of cGAS-STING
signaling target cytokines after dosing with SR-717 (15 mg/kg intraperitoneally)
in WT (n=4)orStinggt/gtmice (n= 4). (C) Schematic of therapeutic
treatment strategy of B16.F10 tumor-bearing mice used to evaluate SR-717.
I.P., intraperitoneal. (D) Impact of SR-717 [30 mg/kg intraperitoneally, using
dosing regimen described in (C)] on B16.F10 tumor growth in WT (n=8)or
Stinggt/gtmice (n= 8). (E) Kaplan-Myer survival curve of WT (n=8)or
Stinggt/gtB16.F10 tumor-bearing mice (n= 8) after treatment with SR-717 as
described in (D). Mice were euthanized when tumor area exceeded 2000 mm^3.
(F) Impact of SR-717 or DMXAA positive control (both dosed at 15 mg/kg
intraperitoneally, once per day) on metastasized B16.F10 lung nodule formation
in C57BL/6 mice. Pulmonary nodules were quantified 7 days after intravenous


tail vein administration of B16.F10 cells (n= 5 mice for vehicle,n= 5 for SR-717,
andn= 3 for DMXAA). Each data point represents the number of nodules per set
of lungs in each mouse. **P≤0.01; n.d., no difference. (G) Representative
images of isolated lungs from studies described in (F). (H) Impact of SR-717
[n= 8, 30 mg/kg intraperitoneally, using dosing regimen described in (C)
starting on day 10]; anti-PD-1 antibody (n= 8, 200mg on days 10, 14, and 17);
or combination SR-717 plus anti–PD-1 treatment (n= 8) on B16F.10 tumor
growth in WT C57BL/6 mice. (I) Kaplan-Myer survival curve of WT B16.F10
tumor-bearing mice (n= 8) after treatments described in (H). (J) Impact of
SR-717 [30 mg/kg intraperitoneally, using dosing regimen described in (C)
starting on day 11] (n= 8); anti-PDL1 antibody (200mg on days 11, 14, and 17)
(n= 8); or combination thereof (n= 8) on B16F.10 tumor growth in WT C57BL/6
mice. (K) Kaplan-Myer survival curve of WT B16.F10 tumor-bearing mice (n=8)
after treatments described in (J). Data are representative of three independent
experiments, and values are the mean ± SEM [(A), (B), and (D) to (K)].

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