Engineered peptide PLG0206 overcomes limitations of a challenging antimicrobial drug class

Abstract

The absence of novel antibiotics for drug-resistant and biofilm-associated infections is a global public health crisis. Antimicrobial peptides explored to address this need have encountered significant development challenges associated with size, toxicity, safety profile, and pharmacokinetics. We designed PLG0206, an engineered antimicrobial peptide, to address these limitations. PLG0206 has broad-spectrum activity against >1,200 multidrug-resistant (MDR) ESKAPEE clinical isolates, is rapidly bactericidal, and displays potent anti-biofilm activity against diverse MDR pathogens. PLG0206 displays activity in diverse animal infection models following both systemic (urinary tract infection) and local (prosthetic joint infection) administration. These findings support continuing clinical development of PLG0206 and validate use of rational design for peptide therapeutics to overcome limitations associated with difficult-to-drug pharmaceutical targets.

Fig 1. The primary sequence and structural models of PLG0206.

Primary sequence: H-RRWVRRVRRVWRRVVRVVRRWVRR-NH2. Structural models: (a) helical wheel water-excluding surface; (b) diagram 3D helical structural model. Fig 1A was reproduced (with changes) from Fig 1 of Deslouches et al. Antimicrob Agents Chemother 59, 1329–1333 (2015) [19] which is covered by Creative Commons Attribution 4.0 license. 3D, three-dimensional; R, arginine; V, valine; W, tryptophan.

Fig 2. PLG0206 is effective at treating PJI intraoperatively.

(a) X-ray verification of Kirschner wire implant into the rabbit tibial canal. (b) In vivo CFU analysis of PLG0206 efficacy using 1 mg/mL PLG0206 to treat PJI. Data are mean (standard deviation). Kruskal–Wallis statistical analysis was performed using GraphPad Prism version 9. *P<0.01 and **P<0.05. (c) Survival analysis of PBS vehicle (I&D alone), DAIR (PBS vehicle + cefazolin), and DAIR+ PLG0206 was performed over 28 days. Shaded region indicates 95% confidence intervals, and no overlap indicates statistical significance (P<0.05). CFU, colony-forming units; DAIR, debridement and antibiotics with implant retention; I&D, irrigation and debridement; PBS, phosphate-buffered saline; PJI, periprosthetic joint infection.

Fig 3. In vitro activity of the broad-spectrum engineered peptide antibiotic PLG0206.

(a) MICs in mg/mL in sensitive and MDR bacterial strains. PLG0206 displays broad-spectrum activity and overcomes key resistant phenotypes. MDR where indicated is defined as resistance to ≥3 different antimicrobial classes/subclasses. ESBL screen based on ceftazidime MIC. (b) Bactericidal activity against planktonic bacteria. PLG0206 exhibits ≥3-log₁₀ reduction in CFU/mL within 5 min of exposure. Levofloxacin was tested at 16-fold the MIC for each evaluated isolate. Levofloxacin MIC values were as follows: S. aureus NRS1 (16 mg/mL); S. epidermidis (0.25 mg/mL); P. aeruginosa (1 mg/mL); A. baumannii (1 mg/mL). (c) Bactericidal activity against biofilm bacteria grown on stainless steel wires. Top and bottom dotted line denote mean biofilm density and 3-log reduction, respectively. Data are mean from pooled data (standard deviation). Statistical comparisons (PLG0206 vs vehicle control) were performed with GraphPad Prism version 9 using Student’s t-test. *P<0.05. CAZ, ceftazidime; CFU, colony-forming units; CLI, clindamycin; COL, colistin; CRE, carbapenem-resistant; DAP, daptomycin; DOX, doxycycline; ESBL, extended spectrum beta-lactamase; LOD, limit of detection; LVX, levofloxacin; LZD, linezolid; MDR, multidrug resistant; MEM, meropenem; MIC, minimum inhibitory concentration; MRSA, methicillin-resistant S. aureus; MRSE, methicillin-resistant S.epidermidis; M/V, meropenem/vaborbactam; TOB, tobramycin; VAN, vancomycin; VRE, vancomycin-resistant enterococci; VSE, vancomycin-susceptible enterococci; -, no resistance breakpoint available.