preclinical approaches: what is of combinations t. tsuji ......what about the in vivo picture other...
TRANSCRIPT
19/06/2013
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Preclinical approaches: What is important – synergy or activity
of combinations
Brian T. Tsuji, Pharm.D.Assistant Professor of Pharmacy
School of Pharmacy and Pharmaceutical Sciences
University at Buffalo, State University of New York
Director, Laboratory for Antimicrobial Pharmacodynamics
Rationale for Polymyxin Combinations
An increasing body of evidence based on in vitro and clinical studies demonstrate that colistin monotherapy results in emergence of resistance (at increasing bacterial densities) and poor clinical outcomes in patients.
Clinical Practice Yesterday (May 2nd) Prato Conference:
Dr. David Patterson: Polymyxin monotherapy is inferior to combinations against CRE
Dr. Mical Paul: Colistin is not as effective as Beta‐lactams
Dr. Alexandre Zavascki: Empiric therapy now involves combinations 3 drugs with polymyxin
Dr. Helen Giamarellou: Empiric therapy involves carbapenem and colistin
Dr. Nation: The difficulty of achieving adequate formed colistin conc. in patients with normal to high CLcr
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Goal of Combination Antibiotic Therapy: Polymyxin and Second Antibiotic
CombinationTherapy
Killing Resistance
Maximize Minimize
Differing Mechanisms of Action & PK/PD
Optimize combination of antibiotics in difficult to treat infections based PK/PD
strategies
Exploit
Toxicity
Minimize
What agents do we have left: Combinations with differing PK/PD and
Mechanisms of Action
AUC/MICPolymyxin
T>MICCarbapenem
Cmax/MICAminoglycosides
Rifampicin
AUC/MICFluoroquinolonesGlycopeptidesTigecycline
MICROBIOLOGICAL SCENARIOS• Susceptible active agents• Intermediate or resistant agents• Agents with no intrinsic activity
CLINICAL SCENARIOS• Empirical at the Beginning of Therapy• Rescue or Salvage Therapy with Colistin• Rescue or Salvage Therapy with 2nd Abx
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Heterogeneous Resistance to Polymyxins
Li et. al. AAC. 2006.Li et. al. CID 2007.
Colistin monotherapyAmplification of colistin‐resistant sub‐population
Colistin‐susceptible population
Colistin‐resistant sub‐population
Colistin
Slide from J. Li & R.L. Nation
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Promising therapeutic optionsColistin + second antibiotic
Colistin‐susceptible population
Colistin‐resistant sub‐population
Colistin 2nd antibiotic
May not be a synergistic effect against a homogeneous population
Rather, different antibiotics tacklingtheir respective susceptible populations
Slide from J. Li & R.L. Nation
0 24 48 72 96 120 144 168 192 216 2400
2
4
6
8
10
12
Log 1
0(C
FU
/mL)
Time (h)
Total Population 0.5 mg/L colistin1 mg/L colistin2 mg/L colistin3 mg/L colistin4 mg/L colistin6 mg/L colistin8 mg/L colistin10 mg/L colistin
Polymyxin Monotherapy results in Rapid Emergence of Resistance
colistin monotherapy(5mg/L CI) vs. hetero‐resistant P. aeruginosa.
Amplification of resistance in the HFIM with colistin monotherapy.
Ly NS, Rao G, Kelchlin PA, Holden PN, Forrest A, Bulitta JB, Bergen PJ, Nation RL, Li J, Tsuji BT. ICAAC.2011.
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Challenges when combining agents: Do any of the Traditional Methods apply ?
1) Checkerboard Synergy Methods 2) Time Kill Methods
A 2.0 log10 increase in killing as measured by viable cfu/ml between the combination and the most active agent
Fractional Inhibitory Concentration (FIC) =
MIC A (with B) + MIC B (with A)MIC A MIC B
<0.5 Synergy>0.5 to 4.0 Additivity/Indifference
>4.0 Antagonism
Combination
Mono
Lorrian V. Antibiotics in Laboratory Medicine. 2005.
Synergy with Polymyxin Antibiotics: Examples for colistin based on FIC
Year 1st Author Journal Polymxyin 2nd Agent Bug Synergy
1993 Richards J. Pharm
Colistin &Polymyxin B
Cipro PA 2 strains SynergyFIC <1.0
2006 Tascini Int J. Wound
Colistin ImipenemRifampin
PA Case Report: Synergy based on FIC
2004 Tascini J. Chem Colistin Rifampin PA 1 of 7 strains Fully Synergy based on FIC
2006 Timurkaynak IJAA Colistin Rifampin ABPA
4 Fully synergistic 2 Fully synergisticFIC <0.5
2011 Mitsugui IJAA Colistin Polymyxin B
CeftazP/T
PAPA
35% Strains Synergy24% Strains SynergyFIC <0.5 of 34 strains
Not an comprehensive list
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Polymyxin Combinations based on FIC
ABisolates (8)
PB, mean Etest MIC
MER, mean Etest MIC
Synergy method (1× MIC), mean ∑FIC
TKA (change after 24 h)
Log10change PB 1× MIC + MER 1×MIC
Log10change PB 1/2 MIC + MER 1×MIC
Log10change PB 1/4 MIC + MER 1×MIC
A 0.5 24 0.5 syn −4.4 syn −5.0 syn −5.0 syn
B 0.5 >32 0.5 syn −2.7 syn −5.0 syn −4.3 syn
C 0.5 32 0.4 syn −3.2 syn −5.0 syn −5.0 syn
D 0.5 >32 0.5 syn −4.3 syn −3.4 syn −3.3 syn
E 0.5 >32 0.4 syn −2.2 syn −2.0 syn −2.3 syn
F 0.5 24 0.6 ind −4.2 syn −3.1 syn −3.1 syn
G 0.5 >32 1.1 ind −4.6 syn −5.0 syn −5.0 syn
H 0.5 >32 0.7 ind −3.6 syn −4.2 syn −5.0 syn
Pankey GA, Ashcraft D. DMID. 2009.
Polymyxin Combinations based on Time Killing Experiments
Time (Hour)
0 24
Log
10
CF
U/m
l
0
1
2
3
4
5
6
7
8
9
10
Growth ControlMeropenem 1 X MICPolyB 1 X MICMeropenem PolyB Combo at 1 x MIC
Growth Control
Meropenem 1 x MICPolyB 1 x MIC
Meropenem 1 x MIC + PolyB 1 x MIC
Pankey GA, Ashcraft D. DMID. 2009.
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Preclinical Studies for Effective TranslationStudy Limitations:
• Checkerboard FICs are based Turbidity• Time points of FICs are based on an incubation of 24h, of growth is dynamic
• Concentrations selected are below the MIC may not be clinical relevant
• Duration of static time kill systems may not be enough to allow for resistance
• Studies do not capture dynamic course of microbial populations in the case of heteroresistance over an extended duration
• Impact of Inoculum
The presence of in vitro synergy by itself is unimportant unless it is accompanied by activity in a clinically relevant context.
Is our eye on the wrong ball ?
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Adapted from NIAID/NIH : Grant R01A1079330 Grant (PI: Nation. Co-I: Li)
Synergy Panel ExperimentsRifampin, Ciprofloxacin, Doripenem, Imipenem, Ceftazidime
In vitro static time killImipenem, Doripenem, Rifampin
In vitro one compartmentDoripenem, Imipenem, Rifampin
Hollow fiber modelDoripenem, Rifampin
Animal Infection ModelsDoripenem, Rifampin
Translational Approaches for Combinations
Driven by PK/PD
36 Strains, 12 for each species: P. aeruginosa, A. baumanniiK. pneumoniae:1 PolymyxinS
1 PolymyxinHR
1 PolymyxinR
Brian
Colistin (mg/L)
0 1 2 3 4 5 6 7 8 9 10
Lo
g10
CF
U/m
L
2
3
4
5
6
7
8
9
LOQ
Time (h)
0 12 24 36 48 60 72 84 96
Lo
g10
CF
U/m
L
2
3
4
5
6
7
8
9
LOQ
A B
Control Col 0.5 mg/L CICol 2 mg/L CIDori Cmax=2.5 mg/L Dori Cmax=25 mg/L Col 0.5 mg/L CI + Dori Cmax=2.5 mg/LCol 0.5 mg/L CI + Dori Cmax=25 mg/LCol 2 mg/L CI + Dori Cmax=2.5 mg/L Col 2 mg/L CI + Dori Cmax=25 mg/L
Control at baselineControl Col 0.5 mg/L CICol 2 mg/L CI Col 0.5 mg/L CI + Dori 2.5 mg/LCol 0.5 mg/L CI + Dori 25 mg/LCol 2 mg/L CI + Dori 2.5 mg/LCol 2 mg/L CI + Dori 25 mg/L
Colistin and Doripenem Against Colistin Hetero-Resistant P. aeruginosa ATCC
MIC: 1 mg/L (Col), 0.25 mg/L(Dori)
Bergen PB et. al. AAC. 2011.
MonotherapyLow Combinations
Combinations
Monotherapy
Combinations
Colistin 0.5 mg/L Continuous Infusion + Doripenem fCmax=25mg/L q8hColistin 2 mg/L Continuous Infusion + Doripenem fCmax=25mg/L q8h
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Colistin and Doripenem Against Colistin Hetero-Resistant P. aeruginosa ATCC
MIC: 1 mg/L (Col), 0.25 mg/L(Dori)
Time (h) Colistin (mg/L)
Log 1
0(CFU
/mL)
Baseline
Total Population Count Population Analysis Profile at 240 h
0 24 48 72 96 120 144 168 192 216 2400
2
4
6
8
10
12
0 24 48 72 96 120 144 168 192 216 2400
2
4
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0 24 48 72 96 120 144 168 192 216 2400
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0 24 48 72 96 120 144 168 192 216 2400
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Col 5 mg/L and Dori
Dori alone
Col 2 mg/L and Dori
Ly N. et. al. ICAAC.2011.
Col 2 mg/LCol 5 mg/L
Col 2 mg/LCol 5 mg/L
COMBOs
0 24 48 72 96 120 144 168 192 216 2400
2
4
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8
10
12
Colistin (mg/L)
Time (h) Colistin (mg/L)
Colistin and Doripenem Against Colistin Hetero-resistant P. aeruginosa
MIC: 1 mg/L (Col), 1 mg/L(Dori)
Total Population Count Population Analysis Profile at 240 h
0 24 48 72 96 120 144 168 192 216 2400
2
4
6
8
10
12
Col 2 mg/L and DoriCol 5 mg/L and Dori
Log 1
0(CFU
/mL)
Ly N. et. al. ICAAC.2011.
Col 2 mg/LCol 5 mg/L
Dori
COMBOs
Col 5 mg/L
Col 2 mg/L
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Colistin (mg/L)
Log 1
0 (CFU
/mL)
Time (h)
Colistin and Doripenem against Colistin Resistant P. aeruginosa
MIC: >128 mg/L (Col), 1 mg/L(Dori)
Total Population Count Population Analysis Profile at 240 h
0 24 48 72 96 120 144 168 192 216 2400
2
4
6
8
10
12
0 24 48 72 96 120 144 168 192 216 2400
2
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0 24 48 72 96 120 144 168 192 216 2400
2
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Col 2 mg/L and Dori
Col 5 mg/L and Dori
Ly N. et. al. ICAAC.2011.
Col 2 mg/LCol 5 mg/L
Dori
What about the in vivo picture in mice
Points to consider in animal infection models• Animal Scaling to humanize pharmacokinetics• Clinical relevant doses in mg/kg (e.g. same mg/kg dose as used in patients)
unlikely to have human PK• Confirmation of plasma concentrations
Pachon‐Ibanez et. al. AAC 2010. Colistin + rifampicin in murine pneumonia Model.
Mutlu Yilmaz et. al. IJAA 2012.Efficacy of tigecycline + colistin in murine pneumonia model.
Song et. al. IFAA 2009. Colistin + rifampicin in A. baumannii murine pneumonia model.
Aoki et. al. JAC 2012. Colistin + rifampicin P. aeruginosa murine pneumonia.
Lee HJ, ECCMID, 2012. Colistin + rifampicin versus A. baumannii ATCC 19606.
(Not a comprehensive list)
Dr. Bulitta Talk Next
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What about the in vivo picture other models
G. mellonella, Larvae of wax moth, have been used to study pathogenicity
Colistin Alone <50% Survival
Colistin Combo100% Survival
Hornsley et. al. AAC. 2012.
Acknowledgements
US
Alan Forrest
Neang Ly
Gauri Rao
Samira Garonzik
George Drusano
Arnold Louie
Jenny Yang
Robert Hancock
Peter Greenberg
Patty Holden
Australia
Roger L. Nation
Jian Li
Juergen Bulitta
Cornelia Landersdorfer
John Boyce
David Paterson
Hongmei Xu
Funding:
NIAID/NIH: R01AI079330 to RL Nation
AFPE Fellowship to NSL
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Thank you for your attention
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