Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jan;52(2):458-468.
doi: 10.1007/s00259-024-06927-z. Epub 2024 Oct 11.

Preclinical evaluation of 225Ac-labeled minigastrin analog DOTA-CCK-66 for Targeted Alpha Therapy

Nadine Holzleitner  1 , Meryl Vilangattil  2 , Abir Swaidan  2 , Clara Diaz Garcia-Prada  2 , Marco F Taddio  2 , Pauline Jeanjean  2 , Christine E Mona  2 , Constantin Lapa  3 , Angela Casini  4   5 , Thomas Günther  4   6 , Giuseppe Carlucci  7
Affiliations

Preclinical evaluation of 225Ac-labeled minigastrin analog DOTA-CCK-66 for Targeted Alpha Therapy

Nadine Holzleitner et al. Eur J Nucl Med Mol Imaging. 2025 Jan.

Abstract

The recently developed metabolically more stable minigastrin derivative, DOTA-CCK-66, displayed promising preclinical data when labeled either with 68Ga or 177Lu. First positron emission tomography/computed tomography (PET/CT) imaging using [68Ga]Ga-DOTA-CCK-66 in two patients suffering from medullary thyroid carcinoma (MTC) displayed a favorable biodistribution profile. Here, we aim to investigate the therapeutic potential of [225Ac]Ac-DOTA-CCK-66 as a targeted α-therapy (TAT) agent in a comparative treatment study of [177Lu]Lu- versus [225Ac]Ac-DOTA-CCK-66.

Methods: Treatment studies were performed (3 groups, n = 5, AR42J tumor-bearing 394-NOD SCID mice). Control group animals were injected with [68Ga]Ga-DOTA-CCK-66 (1.1 MBq, PET/CT imaging), while treatment group animals received a single dose of either [177Lu]Lu-DOTA-CCK-66 (37 MBq, radioligand therapy (RLT)) or [225Ac]Ac-DOTA-CCK-66 (37 kBq, TAT). All animals' tumor volume and body weight were monitored twice a week until end-point criteria were reached. Blood samples were evaluated (VetScan VS2, Abaxis) once mice were sacrificed.

Results: Upon treatment, an initial decline in tumor volume, followed by a significantly delayed tumor growth of treated cohorts, was observed. Mean survival of 177Lu- as well as 225Ac-treated animals was increased by 3- (37 ± 3 d) and 4.5-fold (54 ± 6 d), respectively, when compared to non-treated animals (12 ± 3 d). Blood sample analysis did not indicate toxic side effects to the liver, kidney, or stomach upon 177Lu and 225Ac-treatment.

Conclusion: We demonstrated a substantial therapeutic efficacy of 177Lu- and 225Ac-labeled DOTA-CCK-66. As expected, treatment with the latter resulted in the highest mean survival rates. These results indicate a high therapeutic potential of 225Ac-labeled DOTA-CCK-66 for TAT in MTC patient management.

Keywords: Actinium-225; CCK-2R; MTC; Targeted Alpha Therapy (TAT).

PubMed Disclaimer

Conflict of interest statement

Declarations. Ethics approval: All animal studies were approved by the UCLA Institutional Animal Care and Use Committee, known as the Chancellor’s Animal Research Committee (ARC; # 2005–090). The institutional guidelines for the care and use of animals were strictly followed. Mice were housed under pathogen-free conditions. Water and food were provided ad libitum. 394-NOD SCID mice were injected subcutaneously into the shoulder region. Tumor growth was monitored by CT. Animals were sacrificed upon reaching any of the termination criteria specified in the ARC protocol, including but not limited to apathy, ulceration, severe weight loss, or other signs of deteriorating condition. The study was carried out in compliance with the ARRIVE guidelines. This article does not contain any studies with human participants. Disclosure: A patent application on CCK-2R-targeted ligands, including DOTA-CCK-66, has been filed, with NH, CL, and TG as co-inventors. No other potential conflict of interest relevant to this article was reported.

Figures

Fig. 1
Fig. 1
In vitro characterization of [225Ac]Ac-DOTA-CCK-66. A Stability in human serum after incubation at 37 °C for 1–10 days (n = 3, depicted in green colors), as well as a quality control chromatogram of the 225Ac-labeled peptide (light grey) and a reference chromatogram of free 225Ac (dark grey). B Lipophilicity depicted as distribution coefficients at pH = 7.4 (logD7.4) of [225Ac]Ac-DOTA-CCK-66, [177Lu]Lu-DOTA-CCK-66 and [67Ga]Ga-DOTA-CCK-66. *Data taken from Günther et al. [24]. C CCK-2R expression of AR42J cells as determined by flow cytometry using a polyclonal CCK antibody
Fig. 2
Fig. 2
Study design of animal experiments (5 × 5 animals). AR42J tumors are depicted as black dots. Blood sample analysis of 177Lu- and 225Ac-treated tumor-bearing and naïve mice was performed
Fig. 3
Fig. 3
Representative PET/CT scan ([68Ga]Ga-DOTA-CCK-66; 1.1 MBq, 30 pmol) of a control group AR42J tumor-bearing mouse on day 0 of the experiment. Tumor is indicated with a white arrow
Fig. 4
Fig. 4
A Tumor growth inhibition, B body weight and (C) Kaplan-Meyer curves of AR42J tumor-bearing mice treated with [225Ac]Ac-DOTA-CCK-66 (37 kBq, n = 5) or [177Lu]Lu-DOTA-CCK-66 (37 MBq, n = 5), compared to untreated control (n = 5)
Fig. 5
Fig. 5
Blood values of untreated control (AR42J tumor, n = 5) versus AR42J tumor-bearing 394-NOD SCID treatment group mice ([225Ac]Ac-DOTA-CCK-66: 37 kBq, n = 5 and [177Lu]Lu-DOTA-CCK-66: 37 MBq, n = 5) as well as naïve animals injected either with [225Ac]Ac-DOTA-CCK-66 (37 kBq, n = 5) or [177Lu]Lu-DOTA-CCK-66 (37 MBq, n = 4)
Fig. 6
Fig. 6
Representative images of (A) HE as well as (B) IHC stains of different organs isolated from the untreated control (10–17 d after injection) and [225Ac]Ac-DOTA-CCK-66-treated animals (49–64 d after injection). All images are shown at a 20-fold magnification. Brown staining indicates CCK-2R positivity
See this image and copyright information in PMC

References

    1. Hennrich U, Kopka K. Lutathera(®): the first FDA- and EMA-approved radiopharmaceutical for peptide receptor radionuclide therapy. Pharmaceuticals (Basel). 2019;12. 10.3390/ph12030114. - PMC - PubMed
    1. Fallah J, Agrawal S, Gittleman H, Fiero MH, Subramaniam S, John C, et al. FDA approval summary: lutetium Lu 177 vipivotide tetraxetan for patients with metastatic castration-resistant prostate cancer. Clin Cancer Res. 2023;29:1651–7. 10.1158/1078-0432.Ccr-22-2875. - PMC - PubMed
    1. Sathekge M, Bruchertseifer F, Vorster M, Lawal IO, Knoesen O, Mahapane J, et al. mCRPC patients receiving (225)Ac-PSMA-617 therapy in the post-androgen deprivation therapy setting: response to treatment and survival analysis. J Nucl Med. 2022;63:1496–502. 10.2967/jnumed.121.263618. - PMC - PubMed
    1. Sathekge M, Knoesen O, Meckel M, Modiselle M, Vorster M, Marx S. (213)Bi-PSMA-617 targeted alpha-radionuclide therapy in metastatic castration-resistant prostate cancer. Eur J Nucl Med Mol Imaging. 2017;44:1099–100. 10.1007/s00259-017-3657-9. - PMC - PubMed
    1. Delpassand ES, Tworowska I, Esfandiari R, Torgue J, Hurt J, Shafie A, Núñez R. Targeted α-Emitter therapy with 212Pb-DOTAMTATE for the treatment of metastatic SSTR-expressing neuroendocrine tumors: first-in-humans dose-escalation clinical trial. J Nucl Med. 2022;63:1326–33. 10.2967/jnumed.121.263230. - PMC - PubMed