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Liu Z, Gray BD, Barber C, Bernas M, Cai M, Furenlid LR, Rouse A, Patel C, Banerjee B, Liang R, Gmitro AF, Witte MH, Pak KY, Woolfenden JM. Characterization of TCP-1 probes for molecular imaging of colon cancer. J Control Release 2016; 239:223-30. [PMID: 27574992 DOI: 10.1016/j.jconrel.2016.08.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 08/09/2016] [Accepted: 08/25/2016] [Indexed: 12/11/2022]
Abstract
Molecular probes capable of detecting colorectal cancer (CRC) are needed for early CRC diagnosis. The objective of this study was to characterize c[CTPSPFSHC]OH (TCP-1), a small peptide derived from phage display selection, for targeting human CRC xenografts using technetium-99m ((99m)Tc)-labeled TCP-1 and fluorescent cyanine-7 (Cy7)-labeled form of the peptide (Cy7-TCP-1). (99m)Tc-TCP-1 was generated by modifying TCP-1 with succinimidyl-6-hydrazino-nicotinamide (S-HYNIC) followed by radiolabeling. In vitro saturation binding experiments were performed for (99m)Tc-TCP-1 in human HCT116 colon cancer cells. SCID mice with human HCT116 cancer xenografts were imaged with (99m)Tc-TCP-1 or control peptide using a small-animal SPECT imager: Group I (n=5) received no blockade; Group II (n=5) received a blocking dose of non-radiolabeled TCP-1. Group III (n=5) were imaged with (99m)Tc-labeled control peptide (inactive peptide). SCID mice with human PC3 prostate cancer xenografts (Group IV, n=5) were also imaged with (99m)Tc-TCP-1. Eight additional SCID mice bearing HCT116 xenografts in dorsal skinfold window chambers (DSWC) were imaged by direct positron imaging of (18)F-fluorodeoxyglucose ((18)F-FDG) and fluorescence microscopy of Cy7-TCP-1. In vitro(99m)Tc-HYNIC-TCP-1 binding assays on HCT 116 cells indicated a mean Kd of 3.04±0.52nM. In cancer xenografts, (99m)Tc-TCP-1 radioactivity (%ID/g) was 1.01±0.15 in the absence of blockade and was reduced to 0.26±0.04 (P<0.01) with blockade. No radioactive uptake was observed in the PC3 tumors with (99m)Tc-TCP-1 or HCT116 tumors with inactive peptide. Cy7-TCP-1 activity localized not only in metabolically active tumors, as defined by (18)F-FDG imaging, but also in peritumoral microvasculature. In conclusion, TCP-1 probes may have a distinct targeting mechanism with high selectivity for CRC and tumor-associated vasculature. Molecular imaging with TCP-1 probes appears promising to detect malignant colorectal lesions.
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Affiliation(s)
- Zhonglin Liu
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States.
| | - Brian D Gray
- Molecular Targeting Technologies, Inc., West Chester, PA, United States
| | - Christy Barber
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States
| | - Michael Bernas
- Department of Surgery, The University of Arizona, Tucson, AZ, United States
| | - Minying Cai
- Department of Chemistry & Biochemistry, The University of Arizona, Tucson, AZ, United States
| | - Lars R Furenlid
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States; College of Optical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Andrew Rouse
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States
| | - Charmi Patel
- Department of Pathology, The University of Arizona, Tucson, AZ, United States
| | - Bhaskar Banerjee
- Department of Medicine, The University of Arizona, Tucson, AZ, United States; Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, United States; College of Optical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Rongguang Liang
- College of Optical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Arthur F Gmitro
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States; Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, United States; College of Optical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Marlys H Witte
- Department of Surgery, The University of Arizona, Tucson, AZ, United States
| | - Koon Y Pak
- Molecular Targeting Technologies, Inc., West Chester, PA, United States
| | - James M Woolfenden
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States
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Abstract
OBJECTIVE CT remains the imaging modality of choice in the diagnosis of colorectal cancer (CRC) and anal cancer. However, advances in imaging have expanded the role of MRI and PET/CT. This article focuses on the evolving role of FDG PET/CT in the diagnosis, radiation therapy planning, therapy assessment, and posttherapy monitoring of CRC and anal cancer. CONCLUSION FDG PET/CT is a valuable imaging modality that impacts the clinical management of patients with CRC and those with anal cancer.
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