New Antimicrobial Development

AMR Crisis & Innovation - Drug Discovery Dash

• AMR Crisis: Escalating global threat; ↑ morbidity, mortality, healthcare costs. ESKAPE pathogens are critical.
• Innovation Urgency: "Dry pipeline" for new antibiotics despite urgent need. Economic hurdles (high R&D costs, low ROI) hinder development.
• Discovery Approaches:
  • Traditional: Screening natural products, modifying existing drugs.
  • Modern: Rational drug design, genomics, new targets.
  • Alternatives: Phage therapy, antibodies, anti-virulence agents.
  • Initiatives: Public-private partnerships (e.g., CARB-X, GARDP) crucial for funding.

⭐ The "ESKAPE" pathogens (Enterococcus faecium, S. aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) are notorious for multidrug resistance and are primary targets for new drug development.

Discovery Strategies - Microbe Mission

• Goal: Combat escalating AMR by finding novel agents. 📌 To Make New: Traditional, Modern, Novel.
• Traditional Pathways:
  • Screening natural sources: Soil microbes (e.g., Actinomycetes via Waksman platform), fungi.
  • Chemical derivatization of known antibiotics (semi-synthetic drugs).
• Modern & Innovative Strategies:
  • Genomic approaches: Identifying essential microbial genes/pathways as targets.
  • High-Throughput Screening (HTS) of diverse chemical libraries.
  • Structure-Based Drug Design (SBDD) for rational drug development.
  • Culturing the "unculturable": Technologies like iChip (e.g., Teixobactin discovery).
  • Exploring alternative agents: Bacteriophages, Antimicrobial Peptides (AMPs), anti-virulence compounds.

⭐ Teixobactin, discovered via the iChip platform from previously unculturable soil bacteria, inhibits cell wall synthesis by binding lipid II and lipid III, with no resistance detected to date.

Novel Targets & Next-Gen Drugs - Bug Busters Blueprint

• New Targets:
  • Cell Wall/Membrane: LptD (Gram-negatives), Lipid II/III (Teixobactin for Gram-positives)
  • Virulence Factors: Toxins, adhesins, secretion systems (Anti-virulence agents)
  • Quorum Sensing (QS): Quorum Sensing Inhibitors (QSIs): Anti-biofilm, anti-toxin
  • Efflux Pumps: Efflux Pump Inhibitors (EPIs): Restore existing antibiotic efficacy
• Next-Gen Drugs:
  • Cefiderocol: Siderophore cephalosporin (Trojan horse for MDR Gram-negatives)
  • Newer β-lactam/β-lactamase inhibitors: Avibactam, Vaborbactam, Relebactam combinations
  • Lefamulin: Pleuromutilin (Novel 50S ribosomal binding site)
  • Delafloxacin: Anionic fluoroquinolone (MRSA, Pseudomonas)
  • Phage Therapy: Bacteriophages
  • Antimicrobial Peptides (AMPs)
  • Monoclonal Antibodies (mAbs): Bezlotoxumab (anti-C. difficile toxin B)

⭐ Cefiderocol utilizes a "Trojan horse" mechanism, binding to iron and using bacterial iron uptake systems to enter Gram-negative bacteria, overcoming porin channel mutations and efflux pumps.

Challenges & Future - Pipeline Predicaments

• Economic Disincentives:
  • High R&D cost (>$1B), long development (10-15 yrs).
  • Poor ROI; antibiotics undervalued, short-term use.
• Scientific & Regulatory Bottlenecks:
  • Scarcity of novel targets, especially for Gram-negatives.
  • Strict, prolonged approval pathways.
  • Rapid resistance development post-launch.
• Pipeline Weaknesses:
  • "Valley of death" funding gap.
  • Pharma exodus; small biotechs lead with limited resources.
  • Predominantly existing class modifications, few novel agents.
  • Urgent need for drugs against MDR Gram-negatives (ESKAPE).
• Solutions: New economic models (push-pull incentives, delinkage).

⭐ Globally, fewer than 15 antibiotics with new mechanisms of action have been approved in the last 20 years.

High‑Yield Points - ⚡ Biggest Takeaways

• New antimicrobials primarily target ESKAPE pathogens (e.g., Klebsiella, Acinetobacter).
• Novel mechanisms of action are essential to bypass existing multi-drug resistance.
• Challenges include high R&D costs, a slow discovery pipeline, and poor economic incentives.
• Promising strategies: phage therapy, antimicrobial peptides, combination therapies, vaccines.
• Key new drugs: Cefiderocol (siderophore), Lefamulin (pleuromutilin), Eravacycline (fluorocycline).
• Global initiatives like CARB-X and GARDP are vital for stimulating R&D.
• Optimized PK/PD parameters and stewardship are crucial for new drug longevity.