A New Labeling Method of ^99mTc-PSMA-HBED-CC

Abstract

Objective

⁶⁸Ga-PSMA-HBED-CC (⁶⁸Ga-PSMA-11) was approved by the U.S. Food and Drug Administration as the first prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) imaging drug for patients with prostate cancer. However, the utility of ⁶⁸Ga-PSMA-HBED-CC may be limited due to PET/CT or PET/MR accessibility and ⁶⁸GaCl₃ availability produced from ⁶⁸Ge/⁶⁸Ga generator or cyclotron. Thus, in-house preparation of ^99mTc-PSMA-HBED-CC was developed as an alternative to ⁶⁸Ga-PSMA-HBED-CC to be ubiquitous and affordable in the worldwide population.

Methods

A solution of ^99mTc-pertechnetate was added to PSMA-HBED-CC and 4% SnCl₂·2H₂O in a 10-mL sterile vial. The mixture was heated at 100°C for 15 minutes and then allowed to cool to room temperature. Labeling conditions were optimized to maximize the radiochemical yield of ^99mTc-PSMA-HBED-CC. The chelation completeness was monitored using instant thin layer chromatography, and the stability of ^99mTc-PSMA-HBED-CC was subsequently evaluated.

Results

The radiolabeling of ^99mTc-PSMA-HBED-CC was successful using the appropriate amount of 10 µg PSMA-HBED-CC 3 µg SnCl₂·2H₂O and ^99mTc-pertechnetate 370 MBq at 100°C for 15 minutes, yielded the best result in high radiochemical yield (71.49 ± 2.42%), radiochemical purity (98.29 ± 2.65%), and specific activity of 37.84 ± 1.47 GBq/µmol. ^99mTc-PSMA-HBED-CC is stable with radiochemical purity of more than 95% within 4 hours at room temperature.

Conclusion

A new labeling method of ^99mTc-PSMA-HBED-CC was developed. Quality control parameters of ^99mTc-PSMA-HBED-CC met the criteria in accordance with the European Pharmacopoeia.

Keywords

prostate cancer - PSMA-HBED-CC - PSMA-11 - technetium-99m - ^99mTc-PSMA-HBED-CC

Authors' Contributions

B.P. and S.S. contributed to the conceptualization, methodology, formulation, formal analysis, and visualization. B.P. performed the kit manufacturing. S.S. managed funding and acquisition. S.S. was a major contributor in writing the manuscript. All authors have read and agreed to the final version.

Publication History

Article published online:
26 June 2025

• References

• 1 Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 2018; 68 (06) 394-424
• 2 Moe A, Hayne D. Transrectal ultrasound biopsy of the prostate: does it still have a role in prostate cancer diagnosis?. Transl Androl Urol 2020; 9 (06) 3018-3024
• 3 Hennrich U, Eder M. [⁶⁸Ga] Ga-PSMA-11: the first FDA-approved ⁶⁸Ga-radiopharmaceutical for PET imaging of prostate cancer. Pharmaceuticals 2021; 14 (08) 713-725
• 4 Afshar-Oromieh A, Haberkorn U, Eder M, Eisenhut M, Zechmann CM. [⁶⁸Ga]Gallium-labelled PSMA ligand as superior PET tracer for the diagnosis of prostate cancer: comparison with ₁₈F-FECH. Eur J Nucl Med Mol Imaging 2012; 39 (06) 1085-1086
• 5 Silver DA, Pellicer I, Fair WR, Heston WD, Cordon-Cardo C. Prostate-specific membrane antigen expression in normal and malignant human tissues. Clin Cancer Res 1997; 3 (01) 81-85
• 6 Davis MI, Bennett MJ, Thomas LM, Bjorkman PJ. Crystal structure of prostate-specific membrane antigen, a tumor marker and peptidase. Proc Natl Acad Sci U S A 2005; 102 (17) 5981-5986
• 7 Mesters JR, Henning K, Hilgenfeld R. Human glutamate carboxypeptidase II inhibition: structures of GCPII in complex with two potent inhibitors, quisqualate and 2-PMPA. Acta Crystallogr D Biol Crystallogr 2007; 63 (Pt 4): 508-513
• 8 Lundmark F, Olanders G, Rinne SS, Abouzayed A, Orlova A, Rosenström U. Design, synthesis, and evaluation of linker-optimised PSMA-targeting radioligands. Pharmaceutics 2022; 14 (05) 1098-1117
• 9 Barinka C, Byun Y, Dusich CL. et al. Interactions between human glutamate carboxypeptidase II and urea-based inhibitors: structural characterization. J Med Chem 2008; 51 (24) 7737-7743
• 10 Maurer T, Eiber M, Schwaiger M, Gschwend JE. Current use of PSMA-PET in prostate cancer management. Nat Rev Urol 2016; 13 (04) 226-235
• 11 Virgolini I, Decristoforo C, Haug A, Fanti S, Uprimny C. Current status of theranostics in prostate cancer. Eur J Nucl Med Mol Imaging 2018; 45 (03) 471-495
• 12 Li M, Zelchan R, Orlova A. The performance of FDA-approved PET imaging agents in the detection of prostate cancer. Biomedicines 2022; 10 (10) 2533-2556
• 13 Banerjee SR, Foss CA, Castanares M. et al. Synthesis and evaluation of technetium-99m- and rhenium-labeled inhibitors of the prostate-specific membrane antigen (PSMA). J Med Chem 2008; 51 (15) 4504-4517
• 14 Maresca KP, Hillier SM, Lu G. et al. Small molecule inhibitors of PSMA incorporating technetium-99m for imaging prostate cancer: effects of chelate design on pharmacokinetics. Inorg Chim Acta 2012; 389: 168-175
• 15 Lu G, Maresca KP, Hillier SM. et al. Synthesis and SAR of ^99mTc/Re-labeled small molecule prostate specific membrane antigen inhibitors with novel polar chelates. Bioorg Med Chem Lett 2013; 23 (05) 1557-1563
• 16 Robu S, Schottelius M, Eiber M. et al. Preclinical evaluation and first patient application of ^99mTc-PSMA-I&S for SPECT imaging and radioguided surgery in prostate cancer. J Nucl Med 2017; 58 (02) 235-242
• 17 Hillier SM, Maresca KP, Lu G. et al. ^99mTc-labeled small-molecule inhibitors of prostate-specific membrane antigen for molecular imaging of prostate cancer. J Nucl Med 2013; 54 (08) 1369-1376
• 18 Vallabhajosula S, Nikolopoulou A, Babich JW. et al. ^99mTc-labeled small-molecule inhibitors of prostate-specific membrane antigen: pharmacokinetics and biodistribution studies in healthy subjects and patients with metastatic prostate cancer. J Nucl Med 2014; 55 (11) 1791-1798
• 19 Reinfelder J, Kuwert T, Beck M. et al. First experience with SPECT/CT using a ^99mTc-labeled inhibitor for prostate-specific membrane antigen in patients with biochemical recurrence of prostate cancer. Clin Nucl Med 2017; 42 (01) 26-33
• 20 Schmidkonz C, Goetz TI, Kuwert T. et al. PSMA SPECT/CT with ^99mTc-MIP-1404 in biochemical recurrence of prostate cancer: predictive factors and efficacy for the detection of PSMA-positive lesions at low and very-low PSA levels. Ann Nucl Med 2019; 33 (12) 891-898
• 21 Zhang J, Zhang J, Xu X. et al. Evaluation of radiation dosimetry of ^99mTc-HYNIC-PSMA and imaging in prostate cancer. Sci Rep 2020; 10 (01) 4179-4187
• 22 Xu X, Zhang J, Hu S. et al. ^99mTc-labeling and evaluation of a HYNIC modified small-molecular inhibitor of prostate-specific membrane antigen. Nucl Med Biol 2017; 48: 69-75
• 23 Kularatne SA, Zhou Z, Yang J, Post CB, Low PS. Design, synthesis, and preclinical evaluation of prostate-specific membrane antigen targeted ^(99m)Tc-radioimaging agents. Mol Pharm 2009; 6 (03) 790-800
• 24 Sergieva S, Mangaldgiev R, Dimcheva M, Nedev K, Zahariev Z, Robev B. SPECT-CT imaging with [^99mTc] PSMA-T4 in patients with recurrent prostate cancer. Nucl Med Rev 2021; 24 (02) 70-81
• 25 Shi S, Yao L, Li L. et al. Synthesis of novel technetium-99m tricarbonyl-HBED-CC complexes and structural prediction in solution by density functional theory calculation. R Soc Open Sci 2019; 6 (11) 191247-191260
• 26 Vats K, Agrawal K, Sharma R, Sarma HD, Satpati D, Dash A. Preparation and clinical translation of ^99mTc-PSMA-11 for SPECT imaging of prostate cancer. Med Chem Commun 2019; 10 (12) 2111-2117
• 27 Horoszewicz JS, Kawinski E, Murphy GP. Monoclonal antibodies to a new antigenic marker in epithelial prostatic cells and serum of prostatic cancer patients. Anticancer Res 1987; 7 (5B): 927-935
• 28 Lopes AD, Davis WL, Rosenstraus MJ, Uveges AJ, Gilman SC. Immunohistochemical and pharmacokinetic characterization of the site-specific immunoconjugate CYT-356 derived from antiprostate monoclonal antibody 7E11-C5. Cancer Res 1990; 50 (19) 6423-6429
• 29 Kahn D, Williams RD, Seldin DW. et al. Radioimmunoscintigraphy with 111indium labeled CYT-356 for the detection of occult prostate cancer recurrence. J Urol 1994; 152 (5 Pt 1): 1490-1495
• 30 Wynant GE, Murphy GP, Horoszewicz JS. et al. Immunoscintigraphy of prostatic cancer: preliminary results with ¹¹¹In-labeled monoclonal antibody 7E11-C5.3 (CYT-356). Prostate 1991; 18 (03) 229-241
• 31 Eder M, Schäfer M, Bauder-Wüst U. et al. ⁶⁸Ga-complex lipophilicity and the targeting property of a urea-based PSMA inhibitor for PET imaging. Bioconjug Chem 2012; 23 (04) 688-697