IMMIP, Bonn Sabine Specht, Achim Hoerauf NPIMR, Northwick Park Simon Townson Muséum National d’Histoire Naturelle de Paris Coralie Martin
Drug discovery and development for the treatment and control of filariasis: repurposing emodepside
DNDi Robert Don Ivan Scandale
Animal Model of filariasis: Litomosoides sigmodontis
• Litomosoides sigmodontis is transmitted by a mite, Onithonyssus bacoti.
• The parasitized mite transmits third stage larvae (L3) during a blood-meal
• The larvae then migrate from the skin, through the lymphatics, to the thoracic (pleural) cavity where they mature and breed.
• The adult female worms release their microfilariae in the pleural cavity from where they make their way to the blood circulation, ready to be taken up by a mite feeding on the skin.
The only fully permissive model for filarial infections
Final host intermediate host
Adult 28 days Release of MF
55-60 days
L3 L2
L4
Ad
L1
In vitro efficacy: microfilariae
Minimum inhibitory concentration (MIC) = 0.1 µM (∼112 ng/ml) MIC is defined as the minimum concentration producing 100%
reduction of motility
Microfilariae L. sigmodontis Microfilariae A. viteae
MIC for L. sigmodontis adult worms is below 0.1 µM (∼112 ng/ml) (minimum concentration producing 100% reduction of motility)
MIC for O. gutturosa adult worms was measured at 0.048 µM (S. Townson et al. ASTMH 54th annual meeting 2005 abstract 280)
In vitro efficacy: adult worms
M T T A s s a y
1 0 µ M 1 µ M 0 .1 µ M 0.01 µ M 1 0% D M S O H e a t0 .0
0 .2
0 .4
0 .6
OD
550
nm
E m o d e p s i de
Adult worm L. sigmodontis
D0 3 months pi
9-12 weeks pt
Natural infection
Treatment‘s start
Worm recovery & analysis
Analysis: - parasite numbers - length of females/males - microfilariae counts
Patency
Randomization (weight, MF)
L4
Ad
L1
Jird model of filariasis: Litomosoides sigmodontis in jird
Exposure in jird
MIC
Dose mg/kg 12.5 25 70
formulation Suspension 2% Cremophor EL in saline
Cmax (ng/mL) 59 58.6 145
Tmax (h) 2 2.33 3.33
T1/2(h) 22 22 19.7
AUC0-last (ng·h/mL) 567 567 2097
(70 mg/kg)
unt re
a ted
0 0m
g /kg
3d
O 50m
g /k g
O 25m
g/kg
1 2 ,5mg/k
g
0
50
1 00
1 50
num
be
r o
f w
orm
sN
b of
reco
vere
d ad
ult w
orm
s
control
X = animals dead after treatment
3x100 5x50 5x25 5x12.5 mg/kg
Jirds infected with L. sigmodontis
100 mg/kg (3 days)
50 mg/kg (5 days)
25 mg/kg (5 days)
12.5 mg/kg (5 days)
Reduction of adult worms compare to control group 55 % 86 % 22 % 0 %
Formulation Suspension in 2% Cremophor EL Route of administration Oral gavage Readout 9 weeks post treatment
M ic rofila re m ia
Be fore
A fter
0 .1
1
1 0
1 0 0
10 0 0
1 00 0 0
MF
/10
µl
9 9 % r e d u c t io n
5 x 50 mg/kg dose : Cmax = 145 ng/mL AUC0-last = 2097 ng·h/mL
5 x 100 mg/kg dose was not tolerated
*
* = P< 0.05
Adult worms
Efficacy in Jird
Exposure in jird
1
10
100
1000
10000
100000
0 4 8 12 16 20 24
Con
cent
ratio
n (n
g/m
L)
Time (h)
Mean Plasma Concentration of Emodepside after PO Administration at 10 mg/kg
Mean PO2
Mean PO5
MIC
Dose mg/kg 10 10
formulation clear solution 25% Capmul MCM in Corn oil
suspension 10% EtOH/40% Solutol/50% H2O
Cmax (ng/mL) 530 195
Tmax (h) 5 1.67
T1/2(h) 14 21.9
AUC0-last (ng·h/mL) 7390 2612
V e h ic le F B Z 2 m g /k g s c E M O 5 d S E M O 1 0 d S E M O 5 d C E M O 1 0 d C0
50
1 00
1 50
2 00
num
be
r o
f w
orm
s
control FBZ sc 5x2 5x10 10x10 5x10 mg/kg
Nb
of re
cove
red
adul
t wor
ms
10x10
M ic rofila rem ia
B efor e
2 4 h pt
4 wks p
t
8 wk s p
t0
5 00 0
1 0 00 0
1 5 00 0
V e h ic leF B Z 2 m g /kg s cE M O 5 d SE M O 1 0 d SE M O 5 d CE M O 1 0 d C
MF
/10
µl
Jirds infected with L. sigmodontis
5 mg/kg (5 days)
10 mg/kg (10 days)
5 mg/kg (5 days)
10 mg/kg (10 days)
Reduction of adult worms compare to control group 82.9 80.8 89.7 72.8
Route of administration Oral gavage Readout 9 weeks post treatment
40% Solutol suspension
25% Capmul solution
Adult worms
* * * *
The excipient Capmul MCM was not well tolerated in jirds
Treatment duration comparison
* = P< 0.05
Conclusions
Exposure of emodepside depends on the formulation
Reduction > 80% of adult worms is obtained when plasma
levels are close to the in vitro MIC (∼ 112 ng/ml); fulfills efficacy TPP requirements for a macrofilaricide
Longer treatment regimens don't seem to improve the pharmacological response
D0 30 days pi
Treatment start 75 days pt
Natural infection
Begin of treatment
Worm recovery & analysis
Analysis: parasite numbers
length of females/males microfilariae counts
Patency
Randomization (weight, MF)
L4
Ad
L1
Murine model of filariasis: Litomosoides sigmodontis in mouse
u n tre atedE M O 2 5m g /kgE MO 12 ,5 m g/kgE MO 1m g /kg0
2 0
4 0
6 0
8 0
control 5x25 5x12.5 5x1 mg/kg
Nb
of re
cove
red
adul
t wor
ms
Mice infected with L. sigmodontis
25 mg/kg (3 days)
12.5 mg/kg (5 days)
1 mg/kg (5 days)
Reduction of adult worms compare to control group 73 % 82 % 72 %
Formulation Solution 100% capmul MCM Route of administration Oral gavage Readout 75 days post treatment
5 x 50 mg/kg dose was not tolerated
5 x 25 mg/kg was partially tolerated: 2 animals died
Linearity of the pharmacokinetic profile allows extrapolating key PK parameters for 1 mg/kg dose: Cmax = 84 ng/ml
AUC0-last = 1399 ng·h/ml
Adult worms
* * *
* = P< 0.05
Efficacy in mice
Exposure in mouse
MIC
Dose mg/kg 6 12.5 25 50
formulation 100% Capmul MCM clear solution
Cmax (ng/mL) 508 1038 1553 3093
Tmax (h) 12 5.33 20 12
T1/2(h) ND 35.1 ND ND
AUC0-last (ng·h/mL) 8396 16354 25775 53594
Conclusion
Comparable efficacy was obtained at all tested doses (25, 12.5 and 1 mg/kg) Reduction of adult worms is about 80%
Exposure of emodepside depends on the formulation PK parameters of efficacious doses in both mouse and the jird
model are approximatively in the same ballpark: Mouse
1 mg/kg (capmul solution) Cmax = 84 ng/ml AUC0-last = 1399 ng·h/ml
Jird 10 mg/kg (solutol suspension) Cmax = 195 ng/ml AUC0-last = 2612 ng·h/ml