Theranostics at its best: clinical breast cancer imaging and quantification targeting HER2 receptors — ASN Events
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Theranostics at its best: clinical breast cancer imaging and quantification targeting HER2 receptors (#49)

Irina Velikyan 1 2 , Anders Wennborg 3 , Joachim Frldwisch 3 , Helena Olofsson 4 , Dan Sandberg 2 , Mark Lubberink 2 , Mattias Sandström 2 , Henrik Lindman 4 , Jörgen Carlsson 4 , Jens Sörensen 2
  1. PET-Centre, Uppsala University Hospital, Uppsala, Sweden
  2. Section of Nuclear Medicine and PET, Department of Surgical Sciences , Uppsala University Hospital, Uppsala, Sweden
  3. Affibody AB, Solna, Sweden
  4. Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden

The currently best known example of a commercialized theranostics is the combination of HercepTest® and Herceptin® wherein the former is used for HER2 expression assessment and selection of patients that might benefit from the treatment with the latter. However, HercepTest® requires biopsy which is an invasive procedure, not sufficiently accurate, and very difficult to perform on several lesions and repeatedly in order to monitor the treatment response. While positron emission tomography (PET) in combination with HER2 targeting radiopharmaceutical provides quantitative whole body examination which accuracy is high and independent on heterogeneity of receptor expression.

            PET imaging agent, [68Ga]Ga-ABY-025, was produced in compliance with GMP and GRPP in two peptide doses. The peptide Affibody molecule, ABY-025, was provided by Affibody AB. 68Ga was obtained from a 68Ge/68Ga-generator (IGG100, Eckert & Ziegler). Patients with diagnosed metastatic breast cancer were enrolled. Two PET/CT examinations with low and high peptide content radiopharmaceuticals were performed for each patient. The examination started with dynamic acquisition (0-45 minutes) followed by three static runs at 1, 2 and 4 hours post injection. Immunohistochemistry (IHC) on the metastasis biopsies were performed for HER2 expression verification. The study was approved by the Swedish Medical Products Agency (EudraCT 2012-005228-14, NCT01858116) and the Regional Board of Medical Ethics.

            The examination using radiopharmaceutical with high peptide content resulted in higher contrast images with lower uptake in healthy organs such as liver. The contrast increased with the time however already 2 hours post injection was found optimum for routine use. SUVs correlated with IHC HER2-scores. Based on [68Ga]Ga-ABY-025/PET-CT, the treatment was changed in 19% of the patients. 

           [68Ga]Ga-ABY-025/PET-CT demonstrated strong potential to improve patient management efficacy by providing pre-therapeutic accurate whole body determination of HER2 expression extent and treatment response monitoring with minimal patient discomfort.