title: Cetuximab Immunoliposomes Enhance Delivery of 5-FU to Skin Squamous Carcinoma Cells.
abstract: BACKGROUND
  Topical chemotherapy of skin cancers is a promising strategy for reduction of side effects and for improvement of patient compliance. The combination of the chemotherapeutic 5-fluouracil (5-FU) and the anti- EGFR antibody cetuximab is a strategy to inhibit tumor growth. Their skin penetration, however, is hampered by their high hydrophilicity, which could be improved by encapsulation in delivery systems. Furthermore, it is a challenge to encapsulate hydrophilic drugs. The conjugation of an antibody to a liposome, maintaining its activity, is also a difficult task.
  
  
  OBJECTIVE
  Thus, we aimed to develop 5-FU liposomes and cetuximab-conjugated liposomes (immunoliposomes) of 5- FU to improve drug cytotoxicity against skin cancer cells.
  
  
  METHODS
  We characterized them by particle size, zeta potential, loading efficiency and antibody integrity. To optimize the loading efficiency of 5-FU, a series of liposomes were prepared, using different methods and drug-to-lipid ratios.
  
  
  RESULTS
  Liposomes containing DSPC and Chol at drug-to-lipid ratio 0.1 prepared by the thin lipid hydration method resulted in the best 5-FU encapsulation and were chosen to conjugate with cetuximab. Cetuximab was directly coupled to preformed liposomes using DSPE-mPEG2000-Mal as an anchor. In A431 skin carcinoma cells, at 72 h, 5-FU liposomes showed a 5-fold lower IC50 than 5-FU solution. Additionally, 5-FU immunoliposomes resulted in a 4-fold lower cetuximab IC50 than cetuximab solution, demonstrating synergism with a combination index lower than 1 and potential to improve 5-FU and cetuximab cytotoxicity.
  
  
  CONCLUSIONS
  Liposomes and immunoliposomes containing 5-FU were developed and cetuximab remained active as demonstrated in cell culture studies.
authors.forename: Raquel
authors.initials: R
authors.lastname: Petrilli
authors.forename: Josimar O
authors.initials: JO
authors.lastname: Eloy
authors.forename: Renata F V
authors.initials: RF
authors.lastname: Lopez
authors.affiliation: College of Pharmacy, The Ohio State University, Columbus, 500 W 12th Ave, Columbus, OH 43210,United States.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lee
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D000068818:Cetuximab / Q000008:administration & dosage* / Q000494:pharmacology; D005472:Fluorouracil / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000494:pharmacology; D006801:Humans; D018796:Immunoconjugates / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000494:pharmacology; D008081:Liposomes; D012867:Skin / Q000187:drug effects / Q000473:pathology; D012869:Skin Absorption; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D018796:Immunoconjugates; D008081:Liposomes; D000068818:Cetuximab; D005472:Fluorouracil