PT - JOURNAL ARTICLE AU - Jens Sörensen AU - Dan Sandberg AU - Mattias Sandström AU - Anders Wennborg AU - Joachim Feldwisch AU - Vladimir Tolmachev AU - Gunnar Åström AU - Mark Lubberink AU - Ulrike Garske-Román AU - Jörgen Carlsson AU - Henrik Lindman TI - First-in-Human Molecular Imaging of HER2 Expression in Breast Cancer Metastases Using the <sup>111</sup>In-ABY-025 Affibody Molecule AID - 10.2967/jnumed.113.131243 DP - 2014 May 01 TA - Journal of Nuclear Medicine PG - 730--735 VI - 55 IP - 5 4099 - http://jnm.snmjournals.org/content/55/5/730.short 4100 - http://jnm.snmjournals.org/content/55/5/730.full SO - J Nucl Med2014 May 01; 55 AB - The expression status of human epidermal growth factor receptor type 2 (HER2) predicts the response of HER2-targeted therapy in breast cancer. ABY-025 is a small reengineered Affibody molecule targeting a unique epitope of the HER2 receptor, not occupied by current therapeutic agents. This study evaluated the distribution, safety, dosimetry, and efficacy of 111In-ABY-025 for determining the HER2 status in metastatic breast cancer. Methods: Seven patients with metastatic breast cancer and HER2-positive (n = 5) or -negative (n = 2) primary tumors received an intravenous injection of approximately 100 μg (∼140 MBq) of 111In-ABY-025. Planar γ-camera imaging was performed after 30 min, followed by SPECT/CT after 4, 24, and 48 h. Blood levels of radioactivity, antibodies, shed serum HER2, and toxicity markers were evaluated. Lesional HER2 status was verified by biopsies. The metastases were located by 18F-FDG PET/CT 5 d before 111In-ABY-025 imaging. Results: Injection of 111In-ABY-025 yielded a mean effective dose of 0.15 mSv/MBq and was safe, well tolerated, and without drug-related adverse events. Fast blood clearance allowed high-contrast HER2 images within 4–24 h. No anti–ABY-025 antibodies were observed. When metastatic uptake at 24 h was normalized to uptake at 4 h, the ratio increased in HER2-positive metastases and decreased in negative ones (P &lt; 0.05), with no overlap and confirmation by biopsies. In 1 patient, with HER2-positive primary tumor, 111In-ABY-025 imaging correctly suggested a HER2-negative status of the metastases. The highest normal-tissue uptake was in the kidneys, followed by the liver and spleen. Conclusion: 111In-ABY-025 appears safe for use in humans and is a promising noninvasive tool for discriminating HER2 status in metastatic breast cancer, regardless of ongoing HER2-targeted antibody treatment.