Evaluation of treatment efficacy of the 161 Tb- and 177 Lu-Labeled GRPR antagonists AMTG and RM2 in a mouse…

Animal / preclinicalEuropean journal of nuclear medicine and molecular imaging· Jul 2026

Evaluation of treatment efficacy of the 161 Tb- and 177 Lu-Labeled GRPR antagonists AMTG and RM2 in a mouse model of prostate cancer.

Thomas Günther, Abraham S Moses, Elisabeth Günther … Corinne Beinat

Nuclear MedicineAnimal / preclinicalQ1IF 5.8

161Tb-labeled AMTG gave longest median survival in prostate cancer mice

Evaluation of treatment efficacy of the 161 Tb- and 177 Lu-Labeled GRPR antagonists AMTG and RM2 in a mouse model of prostate cancer.

Thomas Günther … Corinne Beinat

European journal of nuclear medicine and molecular imaging · Jul 2026 · Q1 in Radiology

Background

Recent data on 161 Tb-labeled radiopharmaceuticals indicate a benefit in treatment efficacy due to the emission of high-energy Auger and conversion electrons in addition to β particles.

Purpose

We aimed to investigate differences in therapeutic potential of the gastrin-releasing peptide receptor (gastrin-releasing peptide receptor) antagonists RM2 (DOTA-Pip 5 -D-Phe 6 -Gln 7 -Trp 8 -Ala 9 -Val 10 -Gly 11 -His 12 -Sta 13 -Leu 14 -NH 2 ) and AMTG (DOTA-Pip 5 -D-Phe 6 -Gln 7 -α-Me-Trp 8 -Ala 9 -Val 10 -Gly 11 -His 12 -Sta 13 -Leu 14 -NH 2 ) radiolabeled with 161 Tb and 177 Lu in PC-3 tumor-bearing mice.

Methods

Treatment studies in PC-3 tumor-bearing Nu/J mice were initiated once tumor volume was ~ 100 mm 3 .

n = 6

58.1

Results

58.1

± 5.4 d

longer survival than all other tested treatments

n = 6

More results

Animals were assigned to five groups (control, [ 177 Lu]Lu-RM2, [ 177 Lu]Lu-AMTG, [ 161 Tb]Tb-RM2, [ 161 Tb]Tb-AMTG).

Each treatment group received a total activity amount of 26-31 MBq of the respective radiolabeled compound.

No signs of long-term toxicity were observed during this study in any treatment group.

“

Conclusion

The combination of Auger electrons with high in vivo stability of [ 161 Tb]Tb-AMTG resulted in substantially improved tumor control and overall survival in PC-3 tumor-bearing mice, thus expanding the therapeutic potential of gastrin-releasing peptide receptor antagonists in gastrin-releasing peptide receptor-expressing malignancies.

Evaluation of treatment efficacy of the 161 Tb- and 177 Lu-Labeled GRPR antagonists AMTG and RM2 in a mouse model of prostate cancer.

Evaluation of treatment efficacy of the 161 Tb- and 177 Lu-Labeled GRPR antagonists AMTG and RM2 in a mouse model of prostate cancer.

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