activity of pnu 100480 and its major in whole blood and...
TRANSCRIPT
Activity of PNU‐100480 and its major metabolite in whole blood and broth
culture models of TB
Paul Converse1, Jin Lee1, Kathy Williams1, Opokua Amoabeng1, Kim Dionne1, Nicole Parish1, Robert Wallis2, Eric Nuermberger1
1Center for Tuberculosis Research, Johns Hopkins University, Baltimore, MD2Pfizer Inc., Groton, CT
PNU‐100480
• Thiomorpholinyl derivative of linezolid
• In vitro:– MIC = 0.25 μg/ml vs. M. tb H37Rv
• In vivo:– Rapidly metabolized to cmpds with ~ same MIC as parent
Dose‐ranging activity of PNU, LZD in mice
01
23
45
67
8
0 25 50 100 130 260
Dose (mg/kg)
Lung
log1
0 CF
U co
unt
INHPNU-100480Linezolid
D0 count = 7.49
Williams et al, AAC (2009);53:1314
Parameter
Regimen MIC (mg/L) Cmax(mg/L)
AUC0-24(mg-h/L)
PNU-100480 + metab.100 mg/kga
0.25 21.7 117
LZD 130 mg/kgb 0.25 58.4 379aCompiled (i.e., sum of the parent + metab) concentration-time profile used for PK calcs. bFor comparison, steady state values in humans are: Cmax, 18.3-18.8 mg/L; AUC0-24, 215-294 mg-h/L
PNU contributes sterilizing activity to RHZ and novel combinations
Proportion (%) of mice with relapse after treatment for:
Regimen* 3 months 4 months 5 months 6 months
2RHZ + 4RH 18 of 20 (90%) 1 of 20 (5%) 0 of 20 (0%)
2RHZU + 2 RHU 9 of 20 (45%) 1 of 20 (5%)**
2RHZL + 2 RHL 20 of 20 (100%)*R = rifampin, H = isoniazid, Z = pyrazinamide, U= PNU-100480 (sutezolid), L = linezolid**p< 0.005 vs. RHZ/RH control
Williams et al, Am J Respir Crit Care Med 2009Williams et al, Antimicrob Agent Chemother 2012
% (proportion) of mice with relapse after treatment for:
Regimen* 2 months 3 months 4 months
2RHZ/4RH 100% (15/15) 64% (9/14)
JCPaU 93% (14/15) 13% (2/15)** 7% (1/15)*JCPa 100% (15/15) 60% (9 /15) 33% (5/15)
*R = rifampin, H = isoniazid, Z = pyrazinamide, U= PNU-100480 (sutezolid), J = bedaquiline, C = clofazimine, Pa = PA-824 **p< 0.05 vs. RHZ/RH control
Objectives of study
To gain insight into why PNU is more bactericidal than LZD despite achieving lower exposures in mice by:
1. Comparing the concentration‐response profile for LZD and PNU in several in vitro models of:– extracellular infection (broth, plasma), and– intracellular infection (WBA, J774 macrophages)
2. Determining the respective contributions of PNU‐100480 (the parent) and PNU‐101603 (the principal metabolite) in the same assays
Time to positivity in WB cultures
Whole blood activity by calculated log kill
WBA of PNU‐100480 and PNU‐101603
Oxie activity in spiked WB or plasma from healthy volunteers
Time‐kill study in complete 7H9 broth
Time‐kill study in J774 macrophages
Modeling the respective contributions of PNU‘480 and ‘603 in humans
• Developed dose‐response curve for each in vitro model• Used plasma PK profiles from Ph I SAD study to estimate the log CFU ct at each point of sampling
• Using control CFU cts (Time 0 or untreated), calculated the area under the 24‐hr killing (or inhibition) curve for a single 1 g daily dose for each cmpd
• Assumed additivity (based on in vitro checkerboard assay) and calculated the contribution of each cmpd to the overall activity of the combination
Cumulative activity over 24 hrs by model
Conclusions
• In vivo activity of PNU‐100480 likely derives from the combined activity of the parent and the sulfoxide metabolite
• Though the metabolite comprises ~85% of total serum AUC, the parent drives the activity against intracellular bacilli (e.g., WBA, J774, mice?) due to its striking potency advantage
• On the other hand, activity vs. extracellular M.tb may be driven by the more abundant metabolite
• Modeling cell kill based on actual CFU from WB or plasma culture gives results more like human EBA
• The potency advantage of PNU‐100480 over linezolid will likely be smaller against extracellular as opposed to intracellular bacilli
Next steps
• Similar analysis for linezolid • Repeat WBA CFU cts using additional volunteers• More sophisticated models of additive oxie effects, using steady state PK data from humans and mice
• Confirm with one or more additional strains
Acknowledgements• The work
Kathy Williams Rokeya Tasneen Paul Converse Jin LeeOpokua Amoabeng Tong Zhu
• Intellectual supportKen Stover Bob WallisSteve Brickner Mark Mitton-FryColleagues at the TB Alliance
• Funding supportPfizer, NIH (R01-AI-090820)