Folate receptor-mediated enhanced and specific delivery of far-red light-activatable prodrugs of combretastatin A-4 to FR-positive tumor

Bioconjug Chem. 2014 Dec 17;25(12):2175-88. doi: 10.1021/bc500376j. Epub 2014 Nov 21.

Abstract

We examined the concept of a novel prodrug strategy in which anticancer drug can be locally released by visible/near IR light, taking advantage of the photodynamic process and photo-unclick chemistry. Our most recently formulated prodrug of combretastatin A-4, Pc-(L-CA4)2, showed multifunctionality for fluorescence imaging, light-activated drug release, and the combined effects of PDT and local chemotherapy. In this formulation, L is a singlet oxygen cleavable linker. Here, we advanced this multifunctional prodrug by adding a tumor-targeting group, folic acid (FA). We designed and prepared four FA-conjugated prodrugs 1-4 (CA4-L-Pc-PEGn-FA: n = 0, 2, 18, ∼45) and one non-FA-conjugated prodrug 5 (CA4-L-Pc-PEG18-boc). Prodrugs 3 and 4 had a longer PEG spacer and showed higher hydrophilicity, enhanced uptake to colon 26 cells via FR-mediated mechanisms, and more specific localization to SC colon 26 tumors in Balb/c mice than prodrugs 1 and 2. Prodrug 4 also showed higher and more specific uptake to tumors, resulting in selective tumor damage and more effective antitumor efficacy than non-FA-conjugated prodrug 5. FR-mediated targeting seemed to be an effective strategy to spare normal tissues surrounding tumors in the illuminated area during treatment with this prodrug.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antineoplastic Agents, Phytogenic / administration & dosage
  • Antineoplastic Agents, Phytogenic / pharmacokinetics
  • Cell Line, Tumor / drug effects
  • Colonic Neoplasms / drug therapy
  • Colonic Neoplasms / pathology
  • Drug Design
  • Female
  • Folate Receptors, GPI-Anchored / chemistry
  • Folate Receptors, GPI-Anchored / metabolism*
  • Folic Acid / pharmacology
  • Mice, Inbred BALB C
  • Molecular Structure
  • Optical Imaging / methods
  • Photochemotherapy / methods
  • Prodrugs / administration & dosage*
  • Prodrugs / chemistry
  • Prodrugs / pharmacokinetics*
  • Stilbenes / administration & dosage*
  • Stilbenes / pharmacokinetics
  • Tissue Distribution
  • Xenograft Model Antitumor Assays

Substances

  • Antineoplastic Agents, Phytogenic
  • Folate Receptors, GPI-Anchored
  • Prodrugs
  • Stilbenes
  • Folic Acid
  • fosbretabulin