Mehran Makvandi1, Brian P Lieberman2, Ben LeGeyt2, Catherine Hou2, David A Mankoff2, Robert H Mach2, Daniel A Pryma3. 1. Radiological Chemistry and Biology Laboratories, Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104. Electronic address: makvandi@mail.med.upenn.edu. 2. Radiological Chemistry and Biology Laboratories, Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104. 3. Radiological Chemistry and Biology Laboratories, Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104. Electronic address: Daniel.Pryma@uphs.upenn.edu.
Abstract
RATIONALE: The sigma-2 receptor is a protein with a Heme binding region and is capable of receptor-mediated endocytosis. It is overexpressed in many cancers making it a potential vector for therapeutic drug delivery. Our objective was to introduce an alpha-emitting radionuclide, astatine-211, into a selective sigma-2 ligand moiety to provide cytotoxic capabilities without adversely altering the pharmacological characteristics. In this study we investigated the in vitro/in vivo tumor targeting and estimated dosimetry of alpha-emitting sigma-2 ligand, 5-(astato-(211)At)-N-(4-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)butyl)-2,3-dimethoxybenzamide ((211)At-MM3), in a pre-clinical human breast cancer model. METHODS: Astatine-211 was produced in a cyclotron and isolated by dry distillation. Radiosynthesis of (211)At-MM3 was performed using a tin precursor through radioastatodestannylation. In vitro sigma-2 binding experiments using (211)At-MM3 were carried out in live EMT6 and MDA-MB-231 breast cancer cells and liver homogenate tissue. In vivo biodistribution experiments were performed using EMT6 mouse breast cancer cells in BALB/c female mice. Approximately 370 kBq of (211)At-MM3 was administered intravenously and at time points of 5 min, 1, 2, 4, 8, and 24 h organs/tissue were harvested. Estimated human dosimetry was extrapolated from biodistribution data using OLINDA/EXM (VU e-Innovations). RESULTS: Astatine-211 was successfully produced and isolated in quantities suitable for in vitro and small animal in vivo experiments. Radiosynthesis of (211)At-MM3 was reproducible with high radiochemical purity. Astatine-211-MM3 exhibited picomolar affinity to the sigma-2 receptor in contrast to the iodinated analog that had nanomolar affinity. Prolonged tumor targeting was measured through biodistribution studies with a maximal tumor to muscle ratio of 9.02 at 4h. Estimated human dosimetry revealed doses of up to 370 MBq in an adult female patient were below organ radiation limits with the potential to provide a high therapeutic dose to tumors. CONCLUSION: The sigma-2 receptor could serve as a suitable targeting platform for designing radiotherapeutics. (211)At-MM3 showed tumor targeting properties in vitro/in vivo and favorable estimated human dosimetry establishing the proof of concept for future development as a radiotherapeutic for the treatment of breast cancer.
RATIONALE: The sigma-2 receptor is a protein with a Heme binding region and is capable of receptor-mediated endocytosis. It is overexpressed in many cancers making it a potential vector for therapeutic drug delivery. Our objective was to introduce an alpha-emitting radionuclide, astatine-211, into a selective sigma-2 ligand moiety to provide cytotoxic capabilities without adversely altering the pharmacological characteristics. In this study we investigated the in vitro/in vivo tumor targeting and estimated dosimetry of alpha-emitting sigma-2 ligand, 5-(astato-(211)At)-N-(4-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)butyl)-2,3-dimethoxybenzamide ((211)At-MM3), in a pre-clinical humanbreast cancer model. METHODS:Astatine-211 was produced in a cyclotron and isolated by dry distillation. Radiosynthesis of (211)At-MM3 was performed using a tin precursor through radioastatodestannylation. In vitro sigma-2 binding experiments using (211)At-MM3 were carried out in live EMT6 and MDA-MB-231 breast cancer cells and liver homogenate tissue. In vivo biodistribution experiments were performed using EMT6 mousebreast cancer cells in BALB/c female mice. Approximately 370 kBq of (211)At-MM3 was administered intravenously and at time points of 5 min, 1, 2, 4, 8, and 24 h organs/tissue were harvested. Estimated human dosimetry was extrapolated from biodistribution data using OLINDA/EXM (VU e-Innovations). RESULTS:Astatine-211 was successfully produced and isolated in quantities suitable for in vitro and small animal in vivo experiments. Radiosynthesis of (211)At-MM3 was reproducible with high radiochemical purity. Astatine-211-MM3 exhibited picomolar affinity to the sigma-2 receptor in contrast to the iodinated analog that had nanomolar affinity. Prolonged tumor targeting was measured through biodistribution studies with a maximal tumor to muscle ratio of 9.02 at 4h. Estimated human dosimetry revealed doses of up to 370 MBq in an adult female patient were below organ radiation limits with the potential to provide a high therapeutic dose to tumors. CONCLUSION: The sigma-2 receptor could serve as a suitable targeting platform for designing radiotherapeutics. (211)At-MM3 showed tumor targeting properties in vitro/in vivo and favorable estimated human dosimetry establishing the proof of concept for future development as a radiotherapeutic for the treatment of breast cancer.
Authors: Mehran Makvandi; Edouard Dupis; Jonathan W Engle; F Meiring Nortier; Michael E Fassbender; Sam Simon; Eva R Birnbaum; Robert W Atcher; Kevin D John; Olivier Rixe; Jeffrey P Norenberg Journal: Target Oncol Date: 2018-04 Impact factor: 4.493
Authors: Mehran Makvandi; Hwan Lee; Laura N Puentes; Sean W Reilly; Komal S Rathi; Chi-Chang Weng; Ho Sze Chan; Catherine Hou; Pichai Raman; Daniel Martinez; Kuiying Xu; Sean D Carlin; Roger A Greenberg; Bruce R Pawel; Robert H Mach; John M Maris; Daniel A Pryma Journal: Mol Cancer Ther Date: 2019-05-09 Impact factor: 6.261
Authors: Giovanni Nastasi; Carla Miceli; Valeria Pittalà; Maria N Modica; Orazio Prezzavento; Giuseppe Romeo; Antonio Rescifina; Agostino Marrazzo; Emanuele Amata Journal: J Cheminform Date: 2017-01-21 Impact factor: 5.514
Authors: Narges K Tafreshi; Michael L Doligalski; Christopher J Tichacek; Darpan N Pandya; Mikalai M Budzevich; Ghassan El-Haddad; Nikhil I Khushalani; Eduardo G Moros; Mark L McLaughlin; Thaddeus J Wadas; David L Morse Journal: Molecules Date: 2019-11-26 Impact factor: 4.411
Authors: Charles A Kunos; David A Mankoff; Michael K Schultz; Stephen A Graves; Daniel A Pryma Journal: Semin Radiat Oncol Date: 2021-01 Impact factor: 5.934