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

Emodepside (+ praziquantel) is used in topical solutions

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

THANK YOU

IMMIP Sabine Specht NPIMR Simon Townson Muséum National d’Histoire Naturelle de Paris Coralie Martin

DNDi Robert Don Ivan Scandale