Table 2: Advantages and disadvantages of phages as nanomedicines.

Phage nanomedicine platformAdvantagesDisadvantagesReference

Filamentous phages as drug-delivery platformTargeted drug-conjugated filamentous phage nanoparticles are unique antibody-drug conjugates and they have been shown to inhibit target cells in vitro with a potentiation factor of 1000-fold over the corresponding free drug in one study.The pharmacokinetics, the biodistribution, and the immunogenicity of conjugated phages are still under study. Repeated administration of phage results in amplified immune response and rapid neutralization and clearance of the phage.[62]

Phage as antibacterial nanomedicinesPhages are effective against multidrug-resistant pathogenic bacteria; phage specificity prevents damage to original microflora; phages respond quickly to the appearance of resistant bacterial mutants; phages offer low scale-up costs; phages side effects are very rare compared to the antibiotic therapy. Due to the different mechanism of bactericidal action phage provide the opportunity for combined approaches with antibiotics improving antibacterial potency in some cases by up to 2 × 1 0 4 -fold higher than antibiotic alone.Bacterial cells may similarly build resistance against phage infection. Other barriers to infection include restriction or exclusion systems that block propagation. Phage may horizontally transfer toxicity between hosts via generalized or specialized transduction. Some of these barriers may be overcome by using a cocktail strategy, phage incapable of transduction, or genetic modification.[27, 63]

Phages display of peptide as a targeted nanomedicinePhages not only provide the basis to pan for potential peptides that bind a specific receptor but also can serve as a targeting nanomedicine platform to shuttle drugs and/or genes, or to specific cells, or modulate the activity of these receptors.Potential for phage to confer immunogenicity against self antigens that are presented on surface of phage if similar to that found in the mammalian host.[64]
Landscape phage-based approach has decreased drawbacks compared to the chemical modified nanocarriers with cancer-selective peptides. Localized targeting of tumour cells may not be sufficient for some phage-based antitumour strategies.[15]