Preclinical Characterization of DPI-4452: A 68Ga/177Lu Theranostic Ligand for Carbonic Anhydrase IX

Frédéric Massière1, Norbert Wiedemann1, Inês Borrego1, Aileen Hoehne2, Frank Osterkamp2, Matthias Paschke2, Dirk Zboralski2, Anne Schumann2, Anne Bredenbeck2, Franck Brichory1 and Antoine Attinger1

1 Debiopharm International SA, Lausanne, Switzerland

2 3B Pharmaceuticals GmbH, Berlin, Germany

Journal of Nuclear Medicine March 2024, jnumed.123.266309; DOI:


The membrane protein carbonic anhydrase IX (CAIX) is highly expressed in many hypoxic or von Hippel-Lindau tumor suppressor–mutated tumor types. Its restricted expression in healthy tissues makes CAIX an attractive diagnostic and therapeutic target. DPI-4452 is a CAIX-targeting cyclic peptide with a DOTA cage, allowing radionuclide chelation for theranostic purposes. Here, we report CAIX expression in multiple tumor types and provide in vitro and in vivo evaluations of 68Ga-labeled DPI-4452 ([68Ga]Ga-DPI-4452) and 177Lu-labeled DPI-4452 ([177Lu]Lu-DPI-4452). Methods: CAIX expression was assessed by immunohistochemistry with a panel of tumor and healthy tissues. The molecular interactions of complexed and uncomplexed DPI-4452 with CAIX were assessed by surface plasmon resonance and cell-binding assays. In vivo characterization of radiolabeled and nonradiolabeled DPI-4452 was performed in HT-29 colorectal cancer (CRC) and SK-RC-52 clear cell renal cell carcinoma (ccRCC) human xenograft mouse models and in healthy beagle dogs.