Experimental treatment of M.ulcerans disease

Jacques H. Grosset, MD

Center for TB ResearchJohns Hopkins UniversitySchool of MedicineBaltimore, MD

March 13-14, 2006

Relationship between Cmax & MIC MIC** (µg/ml)Cmax

(µg/ml)

0.5 - 12-3

10-20

15 - 252 - 4

15 - 208 - 10

0.06>162.0

2.00.5

0.52.0

MIC 90

0.03160.5

≤0.015 - 0.12≤4.0 - >16≤0.25 - 4.0

New compounds:Diarylquinoline (TMC207) 100Nitroimidazopyran (PA-824) 600Linezolid* 600

0.50.12

0.25 - 2.00.015 - >0.5

Other drugs: Amikacin* 500Moxifloxacin* 400

0.250.5

≤0.12 - 1.0≤0.12 - 4.0

TB drugs:Streptomycin*500 (7.5m/kg)Rifampicin* 600 (10mg/kg)

MIC50RangeAntibiotic and dose in mg

*Cost in the USA: from Medicare [SM, $5.60/g; AMK, $26.00/g]; from drugstore.com [RIF, $ 1.66/300mg; MXF, $ 10/400mg; Linezolid, $ 58.90/600mg]** From Ji et al., 2006, in press

In vivo data in the mouse model

Using Shepard’s kinetic method*, we assessed the activity of:

• 8-week daily (5/7) treatment with minocycline, sparfloxacin, clarithromycin, rifampicin (R, RIF), rifabutin (RBT), and amikacin (AMK)

• 4-week daily treatment with clari (as +ve control) streptomycin (SM), AMK, RIF, and AMK+RIF

* Assess the “growth delay” induced by treatment initiated one week after infection with 105 M. ulcerans and given for a limited period.

Onset of foot pad swelling in mice infected with 5x105 AFB of M.ulcerans and daily treated for 8 weeks

0102030405060708090

100

0 5 10 15 20 25

Week

Cum

ulat

ive

prob

abili

ty o

f hav

ing

afo

ot p

ad fr

ee o

f sw

ellin

g

ControlMinoSparfloClariR,Rbt,Amk

8-wk treatment

8 weeks

Onset of foot pad swelling in mice infected with 105 AFB of M.ulcerans and daily treated for 4 weeks

0102030405060708090

100

0 5 10 15 20 25 30 35Weeks

Cum

ulat

ive

prob

abili

ty o

f ha

ving

no

swol

len

foot

pad

controlclariSMAMKRIFAMK+RIF

treatment4w

Onset of foot pad swelling in mice infected with 105 AFB of M.ulcerans and daily treated for 4 weeks

0102030405060708090

100

0 5 10 15 20 25 30 35Weeks

Cum

ulat

ive

prob

abili

ty o

f ha

ving

no

swol

len

foot

pad

controlclariSMAMKRIFAMK+RIF

4w

Conclusion I• Minocycline and levofloxacin had no activity• Moxifloxacin had limited bacteriostatic activity• Sparfloxacin and clarithromycin had potent

bacteriostatic activity• Streptomycin, amikacin, rifampicin and rifabutin had

bactericidal activity (no relapse within the 4 months after completion of 2-month treatment)

• The combination AMK-RIF was strongly bactericidal but given for one month did not prevent relapse in 50% of mice. It was therefore used to treat mice with established M. ulcerans disease for 3 months

Evolution of the average lesion index (ALI) in mice infected with Mycobacterium ulcerans

and started on treatment when foot pads were swollen

0

1

2

3

4

5

6

0 4 8 12 16Week

ALI

of t

he fo

ot p

ad

ControlRR+CL+SPR+AMK

Death

(ALI of foot pad: 0, no lesion; 1, not inflammatory swelling; 2, inflammatory swelling; 3, inflammatory hind foot; 4, inflammatory trunk swelling; 5, death)

Treatment

Long-term follow-up of mice with M. ulceransdisease and treated for 3 months

Activities of the rifampicin-amikacin (R+A) combination given for 4 weeks at once, twice or five times weekly as

measured by the proportional bactericidal test

0.001

0.01

0.1

1

10

100

0 4

weeks

% o

f log

10 v

iabl

e M

.ulc

eran

s

R+A 1/7

R+A 2/7

R+A 5/74.2 log

3.2 log

2.5 log

*

* P<0.01

Conclusion II

• The combination AMK-RIF given for 3 months cured the M. ulcerans disease and was not followed by relapse within the 6 months after treatment completion

• The oral combination RIF+SPX+Clari was less rapidly active and followed by relapse

• RIF alone stabilized the disease and selected resistant mutants in the hands of Marsollier& Carbonnelle (AAC 2003:47: 1228-32)

Next steps?

• Potential of existing drugs? Moxifloxacin

• Potential of new drugs? TMC207, LZD: alone or in combination with RIF

Log10 M.ulcerans CFU per footpad in treated mice

012345678

-6 0 2 4 8 Week

Log 1

0 CFU

controlRIF alone STR aloneMXF aloneRIF+STRRIF+MXF

(Ji et al., 2006, in press)

pretreatment

Rx initiation

MXF

RIF

RIF+MXF

Reduction of log10 M.ulcerans CFU per footpad in treated mice

0

1

2

34

5

6

7

8

-6 0 2 4 8 Week

Log 1

0 CFU control

LZDTMC207RIF+LZDRIF alone RIF+TMC

(Ji et al., 2006, in press)

pretreatment

Rx initiation

R+L

LZD

RIF+TMC

TMC

RIF

To conclude• Existing drugs :

No clear bactericidal benefit of adding MXF to RIF (except for prevention of resistance)

• New drugs:- Nitroimidazopyran (PA-824): not active- Diarylquinoline (TMC207): active but still in development- Linezolid: active

But, no clear benefit of adding TMC207 or LZD to RIF

Conclusion: There is no basis from in vitro and animal studies at present for proceeding with comparative controlled trials to find an alternative to RIF+SM