POSTER NUMBER Activity of Brilacidin (PMX-30063) Against E-1474 Drug Resistant Staphylococci 170 N. Radnor Chester Rd., Suite 300 52nd Interscience Conference on Radnor, PA 19087-5221 USA Antimicrobial and Chemotherapy (ICAAC) 1 1 2 2 3 3 4,5 4,5 R. Scott , B. Korczak , D. Jorgensen , S. Hawser , M. Hackel , S. Bouchillon , Y. Xiong , A. Bayer www.polymedix.com September 9-12 , 2012 Tel:(484) 598-2400 San Francisco, CA, USA 1Polymedix, Radnor, PA; 2IHMA Europe Sàrl, Epalinges, CH; 3IHMA, Inc., Schaumburg, IL, USA; 4LA Biomed. Res. Inst., Torrance, CA; 5Geffen Sch. of Med. at UCLA, Los Angeles, CA ABSTRACT RESULTS: RESULTS: CLINICAL ISOLATE SCREEN Brilacidin vs. ISOGENIC STRAIN PAIRS OF S R Background: Brilacidin (PMX-30063), a small nonpeptidic mimic of host defense MDR S. aureus and MDR CNS DAP and DAP MSSA and MRSA proteins recently completed a Phase 2 clinical trial for treatment of Staphylococcus- associated ABSSSI. Brilacidin is rapidly bactericidal against Gram-positive and Gram- negative pathogens. In the current studies, brilacidin was assessed against multi-drug resistant (MDR) S. aureus and coagulase-negative staphylococci (CNS) and six Table 1: Comparison of brilacidin activity vs. MDR S. aureus (n = 103) Table 4: Susceptibility (MIC and MBC) of the isogenic strain pairs vs. brilacidin S R Isogenic Strain Pairs isogenic strain pairs of daptomycin-sensitive (DAP ) and -resistant (DAP ) MSSA and S R [DAP I DAP ] MRSA. S R S R S R S R S R S R DAP I DAP DAP I DAP DAP I DAP DAP I DAP DAP I DAP DAP I DAP Clav Brilacidin and comparators were tested against 206 MDR staphylococci (103 / Methods: 214 215 11/11 2145 616 701 211 212 282 283 300 755 MDR S. aureus, 103 MDR CoNS). All single patient isolates were from 2010-2011 with Cefoxitin Ceftriaxone Daptomycin Levofloxacin Linezolid Meropenem Minocycline Tigecycline Vancomycin Brilacidin Amox MIC/MBC the exception of 19 isolates collected by the Network on Antibiotic Resistance in 1/1 1/1 1/1 1/1 1/1 1/1 1/1 2/2 1/1 2/2 1/1 1/1 1 >8 >4 >32 1 >4 2 8 0.06 0.12 1 (ug/ml) Staphylococcus aureus (NARSA) which were comprised of 10 vancomycin-resistant, 7 MIC50 2 >8 >4 >32 1 >4 4 >8 0.25 0.25 4 vancomycin-intermediate and 2 linezolid resistant isolates. MICs were determined by MIC90 broth microdilution according to CLSI guidelines. Time-kill studies were done under Mode 1 >8 >4 >32 1 >4 2 >8 0.06 0.12 1 CLSI conditions using polypropylene plasticware. Mean* 1.183 7.429 >4 31.572 0.880 3.313 2.139 4.512 0.088 0.110 1.136 Figure 1: Killing kinetics of brilacidin at 2x, 5x and 10x the MIC Range 1 - 2 2 - >8 4 ->4 16 ->32 0.5 ->2 0.25 ->4 1 - >8 0.03 ->8 ≤0.03 - 4 0.03 – 0.5 0.5 ->8 Results: MIC90 values for MDR staphylococci are shown in the Table below. Brilacidin S R *Geometric Mean; All values expressed as µg/ml; All clinical isolates were collected from 2010 – 2011. Ayala Strain 214 (DAP-S) vs 215 (DAP-R) Strain 11/11 (DAP-S) vs REF2145 (DAP-R) MICs for the DAP and DAP isogenic MRSA strain pairs were equivalent and killing 10.00 10.00 kinetics were rapid at 2x MICs and nearly identical over a 24 hour test period. 9.00 9.00 8.00 214 8.00 11/11 11/11(2X) 7.00 214(2X) 7.00 MIC90 (µg/ml) 214(5X) 11/11(5X) 6.00 Table 2: Comparison of brilacidin activity vs. MDR CoNS (n = 103) 214(10X) 6.00 11/11(10X) 5.00 5.00 2145 CFU/ml Antibiotic MDR S. aureus MDR CoNS NARSA 215 CFU/ml 10 10 2145(2X) 215(2X) 4.00 4.00 215(5X) 2145(5X) log Brilacidin 2 1 2 Log 3.00 3.00 215(10X) 2145(10X) Ceftriaxone >32 >32 >32 2.00 2.00 Clav / 1.00 1.00 Daptomycin 1 1 2 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (h) Time (h) Cefoxitin Ceftriaxone Daptomycin Levofloxacin Linezolid Meropenem Minocycline Tigecycline Vancomycin Levofloxacin >4 >4 >4 Brilacidin Amox Linezolid 4 2 >8 MIC50 1 8 >4 >32 1 >4 1 8 0.25 0.25 2 Strain 616 (DAP-S) vs 701 (DAP-R) Strain 211 (DAP-S) vs 212 (DAP-R) Meropenem >8 >8 >8 1 >8 >4 >32 1 >4 2 >8 0.5 0.5 2 10.00 MIC90 10.00 Minocycline 0.25 0.5 4 Mode 1 >8 >4 >32 1 >4 1 >8 0.06 0.25 2 9.00 9.00 616 8.00 8.00 211 616(2X) 211(2X) Tigecycline 0.25 0.5 0.25 Mean* 0.886 3.665 3.868 24.947 0.790 3.334 1.354 4.045 0.171 0.225 1.508 7.00 7.00 616(5X) 211(5X) 6.00 616(10X) Vancomycin 4 2 >8 Range 0.5 - 2 0.25 - >8 2 ->4 2 ->32 0.25 - 2 0.12 ->4 0.5 - 4 0.03 ->8 ≤0.03 - 4 0.06 – 2 0.5 -4 6.00 211(10X) CFU/ml 701 CFU/ml 5.00 5.00 212 10 701(2X) 10 *Geometric Mean; All values expressed as µg/ml; All clinical isolates were collected from 2010 – 2011; CoNS: 4.00 4.00 212(2X) : Brilacidin exhibited good activity against all MDR S. aureus, MDR CNS 701(5X) Conclusions Log Log 212(5X) coagulase-negative S. aureus 3.00 701(10X) 3.00 212(10X) and 19 NARSA isolates with an MIC range of 0.5 – 2 for the 225 isolates and MIC90 of 1 2.00 2.00 – 2 µg/ml. Excellent bactericidal activity of brilacidin was demonstrated against 6 1.00 1.00 S R 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 isogenic strain pairs of DAP and DAP MSSA and MRSA. These results combined with Time (h) Time (h) a previous screen of 131 MRSA isolates show that brilacidin is highly active in vitro Table 3: Comparison of brilacidin activity against sub-group isolates against MDR staphylococci (e.g. resistant to cephalosporins, daptomycin, levofloxacin, with specific resistance phenotypes (n = 19) Strain 282 (DAP-S) vs 283 (DAP-R) Strain 300 (DAP-R) vs 755 (DAP-S) meropenem and vancomycin). 10.00 10.00 Phenotype 9.00 9.00 282 Clav 8.00 8.00 300 (NARSA / 282(2X) 300(2X) 7.00 7.00 isolates) 282(5X) 300(5X) 6.00 282(10X) 6.00 300(10X) CFU/ml CFU/ml Cefoxitin Ceftriaxone Daptomycin Levofloxacin Linezolid Meropenem Minocycline Tigecycline Vancomycin Brilacidin Amox 5.00 283 5.00 755 10 INTRODUCTION 10 755(2X) 1 >8 >4 >32 2 >4 1 >8 0.06 0.12 2 4.00 283(2X) 4.00 VISA Log Log 283(5X) 755(5X) 3.00 3.00 283(10X) 755(10X) VISA 1 8 >4 >32 2 >4 1 8 1 0.12 2 2.00 2.00 R 1.00 1.00 Host defense proteins (HDPs) are an essential component of the innate immune VISA/Dap 1 8 >4 >32 >2 >4 2 8 ≤0.03 0.06 4 0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (h) Time (h) system and display broad-spectrum action against bacteria, yeast, and fungus by VISA 1 >8 >4 >32 2 >4 2 >8 0.06 0.12 4 specifically disrupting their membranes rather than binding to specific molecular VISA 1 >8 >4 >32 2 >4 2 >8 0.12 0.25 4 Methods. MIC and time kill studies were done under CLSI conditions using polypropylene targets. Importantly, this mechanism is associated with a lower risk for the VISA 1 >8 >4 >32 2 >4 1 >8 ≤0.03 0.06 2 plasticware. All strain pairs are MRSA except 616/701 and 300/755 which are MSSA. development of resistance. It appears that HDPs are ideal therapeutic agents to R LZD 2 >8 >4 >32 1 >4 >8 >8 4 0.25 1 DAPS: daptomycin susceptible; DAPR: daptomycin resistant. treat infections. However, significant problems with stability, tissue penetration and LZDR 2 >8 >4 >32 1 >4 >8 >8 4 0.12 1 toxicity have hampered their clinical progress. PolyMedix has developed a series of R LZD 2 >8 >4 >32 0.5 >4 8 8 0.12 0.12 1 Results. small nonpeptidic mimics of the HDPs which have robust activity against bacteria VRSA 2 >8 >4 >32 1 >4 2 >8 0.5 0.25 >8 Table 4. Brilacidin was bactericidal vs. all strains of S. aureus. The MICs and MBCs for and markedly lower toxicity. The approach is to capture the structural and biological VRSA 1 >8 >4 >32 1 >4 2 >8 0.06 0.06 >8 brilacidin versus the DAPS and DAPR MSSA and MRSA isogenic strain pairs were within 1 properties of the HDPs on a fully synthetic, nonpeptidic framework that would be less VRSA 1 >8 >4 >32 0.5 >4 2 >8 2 0.12 >8 doubling dilution of each other, indicating that mechanisms associated with daptomycin expensive to produce, have better tissue distribution, and be much easier to fine- VRSA 2 >8 >4 >32 0.5 >4 2 >8 2 0.06 >8 resistance had little influence on susceptibility to brilacidin.