Emerging research reinforces Niclosamide’s potential in cancer, antiviral, and anti-inflammatory therapies

By Sacred Leaves Global Medical News | July 2025

Niclosamide—originally an FDA‑approved anthelmintic for tapeworms—is gaining renewed attention. Its low toxicity, cost-effectiveness, and broad target profile are fueling investigations into its use against cancer, viral infections, and inflammatory diseases.

Repurposing Niclosamide: Mechanisms and Applications

Cancer Therapeutics

Niclosamide disrupts several oncogenic pathways, including Wnt/β‑catenin, mTORC1, STAT3, NF‑κB, and Notch, and induces mitochondrial uncoupling—a metabolic stress that inhibits tumor growth PLOS+15PMC+15PMC+15ScienceDirect.
Preclinical research in pancreatic and other solid tumors shows niclosamide causes cell cycle arrest, autophagy-dependent death, and reduced metastasis .
Importantly, niclosamide enhances PD‑1 immune checkpoint therapy by reducing PD‑L1 expression in animal models, leading to better tumor response PMC+15BioMed Central+15ScienceDirect+15.

Antiviral Activity

Early studies highlight niclosamide’s broad antiviral capabilities—including inhibition of SARS‑CoV‑2, respiratory syncytial virus, filoviruses, Zika, and dengue—by disrupting viral replication and cellular pathways PMC.
Reformulations (nebulized/intranasal, nanoparticles) have improved delivery to the respiratory tract for COVID‑19 and long‑COVID, though robust clinical efficacy data remain forthcoming ClinicalTrials.gov+3PMC+3PMC+3.

Antimicrobial and Anti‑Biofilm Potential

Niclosamide shows anti-bacterial and anti-fungal effects by disrupting quorum sensing and biofilm formation—offering a novel strategy against resistant pathogens PMC+13Dove Medical Press+13BioMed Central+13.

Formulations & Pharmacokinetics

Oral niclosamide has limited bioavailability. Recent efforts use salt derivatives (ethanolamine/piperazine) and nanotechnology (liposomes, electrospray) to improve solubility and targeting PMC+1MDPI+1.
A Phase II clinical PK study (NCT04644705) showed new liquid oral formulations are well-tolerated and yield consistent plasma exposure, doubling AUC when taken with food, without major side effects PLOS.

Challenges & Next Steps

• Clinical evidence still limited—most data comes from preclinical models and early human trials.
  
  
• Formulation hurdles remain—bioavailability and delivery mechanisms must be optimized for systemic efficacy.
  
  
• Regulatory clarity needed for actual applications beyond parasitic infections.
  
  

Nevertheless, several ongoing trials, including a Phase II study in metastatic cancers (NCT02519582) and COVID‑19 applications, are underway PMC+4ScienceDirect+4PMC+4PMC+9Frontiers+9MDPI+9ClinicalTrials.gov.

Why It Matters

1. Multi-target approach—niclosamide’s activity across common cancer and viral pathways is a rare benefit.
   
   
2. Cost-effective—existing approval and safety profile reduce development costs.
   
   
3. Innovative delivery—nanotechnology and salt formulations are transforming its therapeutic potential.
   
   

Future Outlook

Niclosamide is poised as a promising repurposed therapeutic—its broad targeting profile, favorable safety, and innovative delivery systems could speed its adoption in oncology and antiviral treatment. Developers should prioritize formulation innovation and robust clinical trials to validate its diverse applications.

Sources:

• Preclinical cancer mechanisms and pathways PMC+15PMC+15MDPI+15MDPI+1Advanced Online Library+1
  
  
• Cancer + immunotherapy synergy
  
  
• Antiviral reviews including COVID‑19 applications
  
  
• PK study via novel oral formulation PLOS+1digitalcommons.unmc.edu+1
  
  
• Solid tumor clinical trial registry
  
  

Anti-biofilm antimicrobial review Dove Medical Press