Reversible Masking Using Low-Molecular-Weight Neutral Lipids to Achieve Optimal-Targeted Delivery

Table 1

Comparison of recent, improved targeted delivery systems.

NP* type	Increase to NT**	Decrease to NT***	Efficacy of targeted delivery system
BIVs + small molecules + reversible masking	200-fold	None	Complete elimination of aggressive, orthotopic pancreatic cancers after 5 iv injections administered once a week [9]
RTNs with endosomally cleavable PEG	2-fold	None	75% reduction in subcutaneous neuroblastoma tumor size after 7 iv injections administered every 48 h [10, 11]
MEND + pH-sensitive fusogenic peptide or a cell penetrating peptide + cleavable PEG	None	2-fold	None reported [12, 13]
FRT + cleavable PEG	1-fold	None	None reported [14]
Copolymers + cleavable PEG	None	None	None reported [15]
Liposomes + cell penetrating peptide + cleavable PEG	1.3-fold	None	None reported [16, 17]

*Nanoparticle (NP).
**Nontargeted (NT); increased delivery of the targeted NP to the target compared with the corresponding nontargeted formulation.
***Nontargeted (NT); decreased delivery of the targeted NP to the target compared with the corresponding nontargeted formulation.