Kirstin A Zettlitz1,2,3, Wen-Ting K Tsai4,2,3, Scott M Knowles4,2,3, Naoko Kobayashi3,5, Timothy R Donahue2,3,6, Robert E Reiter3,5, Anna M Wu4,2,3. 1. Crump Institute for Molecular Imaging, UCLA, Los Angeles, California kzettlitz@mednet.ucla.edu. 2. Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, California. 3. David Geffen School of Medicine, UCLA, Los Angeles, California. 4. Crump Institute for Molecular Imaging, UCLA, Los Angeles, California. 5. Department of Urology, UCLA, Los Angeles, California; and. 6. Division of General Surgery, Department of Surgery, UCLA, Los Angeles, California.
Abstract
Pancreatic cancer has a high mortality rate due to late diagnosis and the tendency to invade surrounding tissues and metastasize at an early stage. A molecular imaging agent that enables both presurgery antigen-specific PET (immuno-PET) and intraoperative near-infrared fluorescence (NIRF) guidance might benefit diagnosis of pancreatic cancer, staging, and surgical resection, which remains the only curative treatment. Methods: We developed a dual-labeled probe based on A2 cys-diabody (A2cDb) targeting the cell-surface prostate stem cell antigen (PSCA), which is expressed in most pancreatic cancers. Maleimide-IRDye800CW was site-specifically conjugated to the C-terminal cys-tag (A2cDb-800) without impairing integrity or affinity (half-maximal binding, 4.3 nM). Direct radioiodination with 124I (124I-A2cDb-800) yielded a specific activity of 159 ± 48 MBq/mg with a radiochemical purity exceeding 99% and 65% ± 4.5% immunoreactivity (n = 3). In vivo specificity for PSCA-expressing tumor cells and biodistribution of the dual-modality tracer were evaluated in a prostate cancer xenograft model and compared with single-labeled 124I-A2cDb. Patient-derived pancreatic ductal adenocarcinoma xenografts (PDX-PDACs) were grown subcutaneously in NSG mice and screened for PSCA expression by immuno-PET. Small-animal PET/CT scans of PDX-PDAC-bearing mice were obtained using the dual-modality 124I-A2cDb-800 followed by postmortem NIRF imaging with the skin removed. Tumors and organs were analyzed ex vivo to compare the relative fluorescent signals without obstruction by other organs. Results: Specific uptake in PSCA-positive tumors and low nonspecific background activity resulted in high-contrast immuno-PET images. Concurrent with the PET studies, fluorescent signal was observed in the PSCA-positive tumors of mice injected with the dual-tracer 124I-A2cDb-800, with low background uptake or autofluorescence in the surrounding tissue. Ex vivo biodistribution confirmed comparable tumor uptake of both 124I-A2cDb-800 and 124I-A2cDb. Conclusion: Dual-modality imaging using the anti-PSCA cys-diabody resulted in high-contrast immuno-PET/NIRF images of PDX-PDACs, suggesting that this imaging agent might offer both noninvasive whole-body imaging to localize PSCA-positive pancreatic cancer and fluorescence image-guided identification of tumor margins during surgery.
Pancreatic cancer has a high mortality rate due to late diagnosis and the tendency to invade surrounding tissues and metastasize at an early stage. A molecular imaging agent that enables both presurgery antigen-specific PET (immuno-PET) and intraoperative near-infrared fluorescence (NIRF) guidance might benefit diagnosis of pancreatic cancer, staging, and surgical resection, which remains the only curative treatment. Methods: We developed a dual-labeled probe based on A2 cys-diabody (A2cDb) targeting the cell-surface prostate stem cell antigen (PSCA), which is expressed in most pancreatic cancers. Maleimide-IRDye800CW was site-specifically conjugated to the C-terminal cys-tag (A2cDb-800) without impairing integrity or affinity (half-maximal binding, 4.3 nM). Direct radioiodination with 124I (124I-A2cDb-800) yielded a specific activity of 159 ± 48 MBq/mg with a radiochemical purity exceeding 99% and 65% ± 4.5% immunoreactivity (n = 3). In vivo specificity for PSCA-expressing tumor cells and biodistribution of the dual-modality tracer were evaluated in a prostate cancer xenograft model and compared with single-labeled 124I-A2cDb. Patient-derived pancreatic ductal adenocarcinoma xenografts (PDX-PDACs) were grown subcutaneously in NSG mice and screened for PSCA expression by immuno-PET. Small-animal PET/CT scans of PDX-PDAC-bearing mice were obtained using the dual-modality 124I-A2cDb-800 followed by postmortem NIRF imaging with the skin removed. Tumors and organs were analyzed ex vivo to compare the relative fluorescent signals without obstruction by other organs. Results: Specific uptake in PSCA-positive tumors and low nonspecific background activity resulted in high-contrast immuno-PET images. Concurrent with the PET studies, fluorescent signal was observed in the PSCA-positive tumors of mice injected with the dual-tracer 124I-A2cDb-800, with low background uptake or autofluorescence in the surrounding tissue. Ex vivo biodistribution confirmed comparable tumor uptake of both 124I-A2cDb-800 and 124I-A2cDb. Conclusion: Dual-modality imaging using the anti-PSCAcys-diabody resulted in high-contrast immuno-PET/NIRF images of PDX-PDACs, suggesting that this imaging agent might offer both noninvasive whole-body imaging to localize PSCA-positive pancreatic cancer and fluorescence image-guided identification of tumor margins during surgery.
Authors: Kan Liu; Eric J Lepin; Ming-Wei Wang; Feng Guo; Wei-Yu Lin; Yi-Chun Chen; Shannon J Sirk; Sebastian Olma; Michael E Phelps; Xing-Zhong Zhao; Hsian-Rong Tseng; R Michael van Dam; Anna M Wu; Clifton K-F Shen Journal: Mol Imaging Date: 2011-06 Impact factor: 4.488
Authors: R E Reiter; Z Gu; T Watabe; G Thomas; K Szigeti; E Davis; M Wahl; S Nisitani; J Yamashiro; M M Le Beau; M Loda; O N Witte Journal: Proc Natl Acad Sci U S A Date: 1998-02-17 Impact factor: 11.205
Authors: D C Saffran; A B Raitano; R S Hubert; O N Witte; R E Reiter; A Jakobovits Journal: Proc Natl Acad Sci U S A Date: 2001-02-13 Impact factor: 11.205
Authors: Lakshmi Sampath; Sunkuk Kwon; Shi Ke; Wei Wang; Rachel Schiff; Michel E Mawad; Eva M Sevick-Muraca Journal: J Nucl Med Date: 2007-09 Impact factor: 10.057
Authors: Kirstin A Zettlitz; Wen-Ting K Tsai; Scott M Knowles; Felix B Salazar; Naoko Kobayashi; Robert E Reiter; Anna M Wu Journal: Mol Imaging Biol Date: 2020-04 Impact factor: 3.488
Authors: Kirstin A Zettlitz; Christopher M Waldmann; Wen-Ting K Tsai; Richard Tavaré; Jeffrey Collins; Jennifer M Murphy; Anna M Wu Journal: J Nucl Med Date: 2019-03-15 Impact factor: 10.057
Authors: Hee-Kwon Kim; Muhammad Rashed Javed; Supin Chen; Kirstin A Zettlitz; Jeffrey Collins; Anna M Wu; Chang-Jin C J Kim; R Michael van Dam; Pei Yuin Keng Journal: RSC Adv Date: 2019-10-09 Impact factor: 4.036
Authors: Mehdi Azizi; Hassan Dianat-Moghadam; Roya Salehi; Masoud Farshbaf; Disha Iyengar; Samaresh Sau; Arun K Iyer; Hadi Valizadeh; Mohammad Mehrmohammadi; Michael R Hamblin Journal: Adv Funct Mater Date: 2020-03-03 Impact factor: 18.808
Authors: Christopher Gromisch; Motaz Qadan; Mariana Albuquerque Machado; Kebin Liu; Yolonda Colson; Mark W Grinstaff Journal: Cancer Res Date: 2020-03-27 Impact factor: 12.701