Targeted Peptides Show Promise for PET Imaging of Tumor-Associated Macrophages
March 23, 2023
TUSKEGEE, AL. – A joint development effort by Riptide Bioscience, Inc., and scientists from the Radiochemistry Laboratory of the Heersink School of Medicine, University of Alabama, have shown that radiolabeled peptides designed by Riptide, specifically identify concentrations of tumor-associated macrophages (TAMs) in a murine cancer model.
This work is the subject of a peer-reviewed manuscript published in the current issue of Pharmaceutics. Riptide’s peptide RP832c was modified to express the chelator DOTA and to incorporate the Gallium-68 isotope. The labeled peptide showed strong and specific affinity to a TAM marker, CD206, through a protein plate assay and surface plasmon resonance analysis. In a CT26 model of colon cancer, positron emission tomographic (PET) uptake values strongly correlated with tumor positioning.
Study director Dr. Suzanne Lapi, Director of the Radiochemistry Laboratory and co-leader of the UAB Experimental Therapeutics Program, commented, “Tumor-associated macrophages are known to play an important role in cancer progression, and to serve as an early indicator of developing metastases and tumor recurrence. Noninvasive detection of TAM concentrations may give physicians a more accurate picture of cancer etiology and help guide the course of treatment.”
Riptide Executive Vice President Dr. Henry Lopez stated, “This work shows that our program of rationally designed CD206-targeting drugs is proving to have wide applicability in inflammatory disease. Therapeutic doses of these peptides have shown efficacy in a number of animal models. We now find that micro-dosing of the same peptides, when radiolabeled, can effectively track the development of disease. So, there’s potential here for a genuinely ‘theranostic’ approach: find and treat the disease with the same class of agents.”
The paper entitled “Evolution of a CD206-Targeted Peptide for PET Imaging of Macrophages in Syngeneic Mouse Models of Cancer,” is available at https://doi.org/10.1021/acs.molpharmaceut.2c00977.
Riptide Bioscience, Inc., with laboratories in Vallejo, California, maintains an intensive program of research into peptide-based therapeutics. Contact: info@riptidebio.com