1681. Activity of the Novel Engineered Antimicrobial Peptide PLG0206 Against Staphylococci and Enterococci

Background

PLG0206 is an investigational, engineered cationic antimicrobial peptide designed to overcome the shortcomings of other natural AMPs, such as toxicity and limited activity. PLG0206 has recently been shown to be well tolerated and safe when administered i.v. in a Phase 1 study. The initial proposed indication for this peptide is the treatment of periprosthetic joint infections via irrigation due to a broad spectrum of activity and anti-biofilm properties. This study evaluated the activity of PLG0206 and comparator antimicrobials against staphylococci and enterococci, causes of periprosthetic joint infections, from the IHMA repository of isolates collected from various world-wide locations in 2019.

Methods

Isolates tested included Enterococcus faecalis (77), E. faecium (75), methicillin-resistant Staphylococcus aureus (MRSA, 180), methicillin-susceptible S. aureus (MSSA, 121) and 152 coagulase-negative staphylococci (CoNS) comprised of S. epidermidis (113), S. haemolyticus (31), S. hominis (4), S. lugdunensis (1), S. saprophyticus (2) and S. simulans (1). Minimum inhibitory concentrations (MICs) were determined by CLSI broth microdilution in cation-adjusted Mueller Hinton broth (CA-MHB), except for PLG0206 which was tested in RPMI medium due to plate-reading difficulties with CA-MHB. The susceptibility of comparators was determined using the 2022 CLSI breakpoints. MDR was defined as resistance to ≥ 3 antibacterial classes.

Results

When tested in RPMI, 18 E. faecalis, 29 E. faecium, 9 S. aureus and 7 CoNS were unable to grow. Summary MIC and susceptibility data for PLG0206 and comparators just including those isolates able to grow in RPMI are shown in the Table. Identical MIC50 and MIC90 values were obtained for PLG0206 when tested against MDR E. faecium (38), MDR CoNS (63) and MDR MRSA (67). Insufficient numbers of MDR MSSA (7) and MDR E. faecalis (4) were tested to accurately evaluate.

Conclusion

PLG0206 was the most potent antimicrobial overall (based on MIC50 and MIC90) against enterococci and CoNS and compared well with the comparators against MRSA and MSSA. These data support the evaluation of this novel antimicrobial peptide as a treatment option for periprosthetic joint infections, including those caused by MDR strains.

Disclosures

David Huang, MD, PhD, Peptilogics: Employee Jonathan Steckbeck, PhD, Peptilogics: I am CEO of Peptilogics.

1680. Activity of the Novel Engineered Antimicrobial Peptide PLG0206 Against Enterobacterales isolates

Background

PLG0206 is an investigational, engineered cationic antimicrobial peptide designed to overcome the shortcomings of other natural AMPs, such as toxicity and limited activity. PLG0206 has recently been shown to be well tolerated and safe in a phase 1 study. This study evaluated the activity of PLG0206 and comparator antimicrobials against Enterobacterales isolates from the IHMA repository collected from various world-wide locations in 2019.

Methods

Isolates tested included Citrobacter spp. (151), Enterobacter cloacae (152), Escherichia coli (300), Klebsiella pneumoniae (300), Morganella morganii (43), Proteus spp. (152), Providencia spp. (61) and Serratia marcescens (45). Minimum inhibitory concentrations (MICs) were determined by CLSI broth microdilution in cation-adjusted Mueller Hinton broth (CA-MHB), except for PLG0206 which was tested in RPMI medium due to plate-reading difficulties with CA-MHB. The susceptibility of comparators was determined using the 2022 CLSI breakpoints. MDR was defined as resistance to ≥ 3 antibacterial classes.

Results

Summary MIC and susceptibility data against Citrobacter spp., E. coli, E. cloacae, and K. pneumoniae are shown in the Table. PLG0206 retained activity against MDR isolates of Citrobacter spp. (26), E. coli (92), E. cloacae (45), and K. pneumoniae (132) with MIC50/90 values of 1/2, 1/2, 1/16 and 8/16 μg/mL, respectively. PLG0206 was essentially inactive against the Morganellaceae and Yersiniaceae isolates tested with MIC50 and MIC90 values of > 32 μg/mL (data not shown).

Conclusion

PLG0206 was active against isolates from the family Enterobacteriaceae, including MDR strains. The spectrum of activity of PLG0206 ranged from being most active against Citrobacter spp. and least active against K. pneumoniae. These data suggest that the novel antimicrobial peptide PLG0206 could be a potential treatment option against infections caused by Enterobacteriaceae isolates.

Disclosures

David Huang, MD, PhD, Peptilogics: Employee Jonathan Steckbeck, PhD, Peptilogics: I am CEO of Peptilogics.

1070. In vitro Activity of PLG0206 Against Isolates Commonly Found in Periprosthetic Joint Infections (PJI)

Background

PLG0206 is a novel engineered cationic antimicrobial peptide being evaluated for treatment of prosthetic joint infections. In this study, the activity of PLG0206 was evaluated by broth microdilution against 104 isolates of Staphylococcus epidermidis, 53 other coagulase-negative staphylococci (CoNS), 3 S. aureus, and 66 Gram-negative isolates consisting of Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii.

Methods

Imipenem, levofloxacin, tigecycline, linezolid, vancomycin, oxacillin, ceftazidime, colistin, and amikacin were tested as comparators. Testing was conducted in accordance with guidelines from the Clinical and Laboratory Standards Institute (CLSI; M7 and M100). Test organisms consisted of reference strains from the American Type Culture Collection, the Centers for Disease Control Antibiotic Reference Bank and clinical isolates from the Micromyx repository. The media employed for testing in the broth microdilution MIC assay for all organisms were cation-adjusted Mueller Hinton Broth and for PLG0206 only included RPMI-1640 medium supplemented with 0.002% P-80.

Results

Activity of PLG0206 in RPMI against CoNS, S. aureus, and resistant Gram-negative* pathogens are shown in Table.

Activity of PLG0206 in RPMI against CoNS, S. aureus and resistant Gram-negative* pathogens

Activity of PLG0206 in RPMI against CoNS, S. aureus and resistant Gram-negative* pathogens

Conclusion

PLG0206 was found to have potent antimicrobial activity when evaluated in RPMI against

S. epidermidis, CoNS non-epidermidis, S. aureus, Enterobacterales, P. aeruginosa, and A. baumannii, including isolates with multi-drug resistance.

Disclosures

David Huang, MD, PhD, Peptilogics (Employee) Jonathan Steckbeck, PhD, Peptilogics (Employee) Chris Pillar, PhD, Micromyx (Employee) Bev Murray, BS, Micromyx (Employee) David Huganfel, BS, Micromyx (Employee) Dean Shinabanger, PhD, Micromyx (Employee)

1040. Knee Explant Analysis (KnEA) Using PLG0206 in Periprosthetic Joint Infection (KnEA Study)

Background

PLG0206 is a novel engineered cationic antimicrobial peptide being evaluated for treatment of prosthetic joint infections (PJI). This study evaluated the rapid bactericidal activity of PLG0206 to decrease biofilm and planktonic bacteria on ex vivo infected prosthesis following removal from patients with chronic PJI.

Methods

De-identified infected prosthetics were removed from nine patients with PJI, despite chronic suppressive oral antibiotics, during a 2-stage revision procedure. Removed prosthetics were then submersed ex vivo to an expected clinical exposure of PLG0206, 1 mg/mL, for ~15 minutes. Upon completion of the 15-minute exposure, the treated explant was placed into buffer and sonicated. The sonication solution was then plated for bacterial analysis including colony forming unit (CFU) enumeration. Remaining explanted implants from the same patient served as a control and was processed similarly but without exposure to PLG0206.

Results

As shown in the Table, both Gram-positive and Gram-negative bacteria were identified from removed prosthetics during a 2-stage revision procedure of chronic PJI. Eight of ten infected prosthetics treated ex vivo to PLG0206 1 mg/mL were sterilized (No. 1-5, 8-10). Of the two infected prosthetics that were not sterilized (No. 6 and 7), one was polymicrobial (No. 6) and the other was monomicrobial (No. 7). Collectively, infected prosthetics exposed to PLG0206 demonstrated a mean 4log10 reduction (range 2 to 7).

Summary of culture and CFU log reduction among infected prosthetics exposed and not exposed to PLG0206

Table: Summary of culture and CFU log reduction among infected prosthetics exposed and not exposed to PLG0206

Conclusion

Overall, these findings support the ongoing development of PLG0206 as a local irrigation solution at 1 mg/mL concentration in the wound cavity for 15 minutes in patients undergoing treatment of a PJI occurring after total knee arthroplasty.

Disclosures

David Huang, MD, PhD, Peptilogics (Employee) Nicholas Pachuda, DPM, Peptilogics (Employee) Despina Dobbins, BS, Peptilogics (Employee) Jonathan Steckbeck, PhD, Peptilogics (Employee) Kenneth Urish, MD, PhD, Peptilogics (Grant/Research Support)

1098. A Phase 1 Safety and Tolerability of Single Ascending Doses of a Novel Engineered Cationic Peptide, PLG0206, in Healthy Subjects

Background

PLG0206 is a novel engineered cationic antimicrobial peptide being evaluated for treatment of prosthetic joint infections (PJI). This abstract presents the results from the first in human study to evaluate the safety, tolerability and pharmacokinetic (PK) profile of PLG0206 when administered as an intravenous (IV) infusion.

Methods

6 cohorts of 8 participants were planned to receive escalating single 1-hour IV infusions of PLG0206 at 0.05, 0.125, 0.25, 0.5, 1, 2 and 3 mg/kg dose or placebo. Participants were randomized to receive either PLG0206 (6 per cohort) or placebo (2 per cohort). At each dose level, there were 2 sentinel participants (1 active, 1 placebo) who were dosed at least 48 hours in advance of the other participants in their group. Serial pharmacokinetic samples were taken prior to infusion and up to 48 post infusion. Safety and tolerability was assessed throughout the study. There was at least a 7-day period after dosing at each of the dose levels before dose escalation.

Results

PLG0206 was safe and well tolerated when administered to healthy volunteers at doses ranging from 0.05 and 1 mg/kg. Therapeutic exposures were achieved at 1 mg/kg. The 2 and 3 mg/kg cohorts were not studied. The incidence of treatment emergent adverse events related to study drug administration was low and most events mild (Grade 1) in severity and was similar between the PLG0206 treatment and placebo groups. There were no SAEs, life-threatening events or deaths throughout the study. IV PLG0206 exhibited linear PK over the dose range of 0.05 to 1.0 mg/kg. The median terminal half-life (t½) ranged from 7.37 to 19.97 hours. AUC_0-∞ increased with increasing PLG0206 dose ranging between 1581.41 and 21141.52 ng.hr/mL. Cmax ranged between 256 and 2653 ng/mL. The mean apparent volume of distribution (Vz) increased was between 25.49 and 94.2 L, mean clearance (CL) were similar across all and ranged from 2.42 to 4.18 L/hour.

Conclusion

Following single IV infusion to healthy volunteers, PLG0206 was safe and well tolerated at doses ranging from 0.05 to 1 mg/kg. IV PLG0206 exhibits linear PK over the dose range. These findings support the ongoing development of IV PLG0206 and will inform dosing regimens in future studies to investigate its utility as an antimicrobial agent.

Disclosures

David Huang, MD, PhD, Peptilogics (Employee) Despina Dobbins, BS, Peptilogics (Employee) Parviz Ghahramani, PhD, PharmD, MSc, MBA, Peptilogics (Consultant) Jonathan Steckbeck, PhD, Peptilogics (Employee)

Novel engineered cationic antimicrobial peptides display broad-spectrum activity against Francisella tularensis, Yersinia pestis and Burkholderia pseudomallei

Broad-spectrum antimicrobials are needed to effectively treat patients infected in the event of a pandemic or intentional release of a pathogen prior to confirmation of the pathogen's identity. Engineered cationic antimicrobial peptides (eCAPs) display activity against a number of bacterial pathogens including multi-drug-resistant strains. Two lead eCAPs, WLBU2 and WR12, were compared with human cathelicidin (LL-37) against three highly pathogenic bacteria: Francisella tularensis, Yersinia pestis and Burkholderia pseudomallei. Both WLBU2 and WR12 demonstrated bactericidal activity greater than that of LL-37, particularly against F. tularensis and Y. pestis. Only WLBU2 had bactericidal activity against B. pseudomallei. WLBU2, WR12 and LL-37 were all able to inhibit the growth of the three bacteria in vitro. Because these bacteria can be facultative intracellular pathogens, preferentially infecting macrophages and dendritic cells, we evaluated the activity of WLBU2 against F. tularensis in an ex vivo infection model with J774 cells, a mouse macrophage cell line. In that model WLBU2 was able to achieve greater than 50% killing of F. tularensis at a concentration of 12.5 μM. These data show the therapeutic potential of eCAPs, particularly WLBU2, as a broad-spectrum antimicrobial for treating highly pathogenic bacterial infections.