Oct. 01, 2025 – Nuclidium AG, a clinical-stage radiopharmaceutical company developing a proprietary copper-based theranostic platform, today announced that it has received a Notice of Allowance from the U.S. Patent and Trademark Office (USPTO) for a patent covering the company’s Kalios-program. Once issued, the composition-of-matter patent will protect a variety of small molecule inhibitors of the fibroblast activation protein (FAP) that can be used in combination with a range of radionuclides bound with a variety of chelating moieties for the diagnosis and treatment of diseases, including solid tumors. The Kalios-program consists of a tumor-targeting FAP inhibitor labeled with a pre-selected copper radioisotope: Copper-61 for diagnostics and Copper-67 for therapeutics. The program is currently in development for the diagnosis and treatment of certain breast and lung cancer indications.
“The Notice of Allowance from the U.S. Patent and Trademark Office is an important milestone for Nuclidium as we continue to advance our best-in-class copper-based radiotheranostics. This initial action from the U.S. Patent office strengthens our intellectual property position in a highly competitive field. It also recognizes the innovation inherent in our approach and supports our long-term goal of addressing unmet needs in oncology, especially in women’s health, through innovative copper-based radiopharmaceuticals. We are committed to building a robust patent portfolio that protects our discoveries and to advancing our copper-based theranostics into clinical evaluation,” said Leila Jaafar, PhD, CEO and Co-Founder of NUCLIDIUM.
The expected patent covers a diverse range of inhibitors that target FAP, representing broad protection for Nuclidium’s current and future radiopharmaceuticals and theranostics in its Kalios-program. FAP is a membrane-bound serine protease (dipeptidyl peptidase) present in epithelial tumors that make up 80-90% of all cancer cases. It is highly expressed on cancer-associated fibroblasts in the tumor stroma as well as in degenerative tissues or inflamed tissues such as bursitis and fibrosis. These characteristics render FAP an attractive target for cancer diagnosis and treatment. Currently approved FAP-targeted radioligands, labelled with either 68Ga or 18F, have a short half-life, which restricts their ability for delayed imaging to identify and treat smaller metastases and, in addition, limits their possible distribution range after production.
Nuclidium and its collaborators recently published a preclinical study in the European Journal of Nuclear Medicine and Molecular Imaging - Radiopharmacy and Chemistry, highlighting the unique potential of copper-based FAP-targeting PET radiotracers. In the study, [61Cu]Cu-Kalios PET radioligands showed favorable pharmacokinetics, high tumor uptake, and strong tumor-to-background ratios with delayed 4h imaging when compared to established FAP-targeting radiotracers. These findings underscore the clinical potential of 61-copper-based radiopharmaceuticals to improve the temporal imaging range for precise detection of FAP-expressing tumors.1
More information is available at nuclidium.com
1. Millul, J., Basaco Bernabeu, T., Gaonkar, R.H. et al. Enhanced contrast in FAP-targeting PET imaging with 61Cu-labeled FAP inhibitors: development and preclinical evaluation of novel [61Cu]Cu-Kalios PET radioligands. EJNMMI radiopharm. chem. 10, 55 (2025). https://doi.org/10.1186/s41181-025-00381-4
March 26, 2026 
