Ex vivo mass spectrometry-based biodistribution analysis of an antibody-Resiquimod conjugate bearing a protease-cleavable and acid-labile linker

Lydia Bisbal Lopez; Domenico Ravazza; Matilde Bocci; Aureliano Zana; Lucrezia Principi; Sheila Dakhel Plaza; Andrea Galbiati; Ettore Gilardoni; Jörg Scheuermann; Dario Neri; Luca Pignataro; Cesare Gennari; Samuele Cazzamalli; Alberto Dal Corso

doi:10.3389/fphar.2023.1320524

Ex vivo mass spectrometry-based biodistribution analysis of an antibody-Resiquimod conjugate bearing a protease-cleavable and acid-labile linker

Front Pharmacol. 2023 Dec 6:14:1320524. doi: 10.3389/fphar.2023.1320524. eCollection 2023.

Authors

Affiliations

¹ Chemistry Department, Università degli Studi di Milano, Milano, Italy.
² R&D Department, Philochem AG, Otelfingen, Switzerland.
³ Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zürich), Zürich, Switzerland.
⁴ Philogen S.p.A, Siena, Italy.

Abstract

Immune-stimulating antibody conjugates (ISACs) equipped with imidazoquinoline (IMD) payloads can stimulate endogenous immune cells to kill cancer cells, ultimately inducing long-lasting anticancer effects. A novel ISAC was designed, featuring the IMD Resiquimod (R848), a tumor-targeting antibody specific for Carbonic Anhydrase IX (CAIX) and the protease-cleavable Val-Cit-PABC linker. In vitro stability analysis showed not only R848 release in the presence of the protease Cathepsin B but also under acidic conditions. The ex vivo mass spectrometry-based biodistribution data confirmed the low stability of the linker-drug connection while highlighting the selective accumulation of the IgG in tumors and its long circulatory half-life.

Keywords: Resiquimod; immune stimulating antibody conjugates; prodrugs; quantitative biodistribution; toll-like receptors.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant agreement No 861316.