title: Evaluation of therapeutic effectiveness of (131)I-antiEGFR-BSA-PCL in a mouse model of colorectal cancer.
abstract: OBJECTIVE
  To investigate the biological effects of internal irradiation, and the therapeutic effectiveness was assessed of (131)I-labeled anti-epidermal growth factor receptor (EGFR) liposomes, derived from cetuximab, when used as a tumor-targeting carrier in a colorectal cancer mouse model.
  
  
  METHODS
  We described the liposomes and characterized their EGFR-targeted binding and cellular uptake in EGFR-overexpressing LS180 colorectal cancer cells. After intra-tumor injections of 74 MBq (740 MBq/mL) (131)I-antiEGFR-BSA-PCL, we investigated the biological effects of internal irradiation and the therapeutic efficacy of (131)I-antiEGFR-BSA-PCL on colorectal cancer in a male BALB/c mouse model. Tumor size, body weight, histopathology, and SPECT imaging were monitored for 33 d post-therapy.
  
  
  RESULTS
  The rapid radioiodine uptake of (131)I-antiEGFR-BSA-PCL and (131)I-BSA-PCL reached maximum levels at 4 h after incubation, and the (131)I uptake of (131)I-antiEGFR-BSA-PCL was higher than that of (131)I-BSA-PCL in vitro. The (131)I tissue distribution assay revealed that (131)I-antiEGFR-BSA-PCL was markedly taken up by the tumor. Furthermore, a tissue distribution assay revealed that (131)I-antiEGFR-BSA-PCL was markedly taken up by the tumor and reached its maximal uptake value of 21.0 ± 1.01 %ID/g (%ID/g is the percentage injected dose per gram of tissue) at 72 h following therapy; the drug concentration in the tumor was higher than that in the liver, heart, colon, or spleen. Tumor size measurements showed that tumor development was significantly inhibited by treatments with (131)I-antiEGFR-BSA-PCL and (131)I-BSA-PCL. The volume of tumor increased, and treatment rate with (131)I-antiEGFR-BSA-PCL was 124% ± 7%, lower than that with (131)I-BSA-PCL (127% ± 9%), (131)I (143% ± 7%), and normal saline (146% ± 10%). The percentage losses in original body weights were 39% ± 3%, 41% ± 4%, 49% ± 5%, and 55% ± 13%, respectively. The best survival and cure rates were obtained in the group treated with (131)I-antiEGFR-BSA-PCL. The animals injected with (131)I-antiEGFR-BSA-PCL and (131)I-BSA-PCL showed more uniform focused liposome distribution within the tumor area.
  
  
  CONCLUSIONS
  This study demonstrated the potential beneficial application of (131)I-antiEGFR-BSA-PCL for treating colorectal cancer. (131)I-antiEGFR-BSA-PCL suppressed the development of xenografted colorectal cancer in nude mice, thereby providing a novel candidate for receptor-mediated targeted radiotherapy.
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Yan-Hui
authors.initials: YH
authors.lastname: Ji
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Cheng-Xia
authors.initials: CX
authors.lastname: Li
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Zhong-Yun
authors.initials: ZY
authors.lastname: Liu
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Fang
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Chang
authors.affiliation: Wei Li, Yan-Hui Ji, Cheng-Xia Li, Ning Li, Jian Tan, Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Tan
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D000068818:Cetuximab / Q000494:pharmacology*; D015179:Colorectal Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics / Q000494:pharmacology*; D008081:Liposomes; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D018613:Microscopy, Confocal; D058990:Molecular Targeted Therapy; D053758:Nanoparticles; D011091:Polyesters / Q000493:pharmacokinetics / Q000494:pharmacology*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000494:pharmacology*; D012710:Serum Albumin, Bovine / Q000493:pharmacokinetics / Q000494:pharmacology*; D000068936:Theranostic Nanomedicine; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D007457:Iodine Radioisotopes; D008081:Liposomes; D011091:Polyesters; D019275:Radiopharmaceuticals; C016240:polycaprolactone; D012710:Serum Albumin, Bovine; C512478:EGFR protein, human; D066246:ErbB Receptors; D000068818:Cetuximab
keywords: Colorectal cancer; Epidermal growth factor receptor; Liposome; Mouse; Radioiodine therapy