Evaluation of extent of breast cancer in a patient with HER2/NEU overexpression using a radiopharmaceutical based on teohnetium-99m-labeled target molecules (case report)

Introduction. Overexpression of Her2/neu is detected in 15-20 % of patients with breast cancer and associated with an aggressive form of disease and low overall and disease-free survival rates. Currently, immunohistochemical studies (iHC) and methods of in situ hybridization are used to assess Her2/neu status. One of significant drawbacks of this detection is the impossibility of simultaneous assessment of the receptor status of the primary tumor and metastatic sites. The increasing popularity of radionuclide methods using recombinant proteins as a targeting module have already demonstrated their effectiveness in solving this question at the initial stages of clinical research. The purpose of this study is to demonstrate a clinical case of assessing the extent of breast cancer in a patient with overexpression of Her2/neu using a radiopharmaceutical based on targeted protein molecules labeled with technetium-99m. Description of the clinical case. A patient diagnosed with stage iiiA right breast cancer (T2N2M0), multicentric growth and metastases in right axillary and subclavian lymph nodes at the diagnostic stage was injected intravenously with 99mTc-ADAPT6 radiopharmaceutical. The drug was prepared in the Department of Nuclear Medicine of Research Cancer institute (Tomsk) immediately before its administration. Planar scintigraphy and single-photon emission tomography of the chest organs were performed 2 hours after injection of 99mTc-ADAPT6 radiopharmaceutical. in addition to the previously described tumors, 3 foci of hyperfixation of the tracer in the projection of the 5th rib on the right along the middle-clavicular line, as well as in the projection of the 8 and 9 thoracic vertebrae (Th Viii, iX) were found. Computed tomography of the chest organs and bone scintigraphy with 99mTc-pyrophosphate showed no metastases in the 5th rib on the right and Th Viii, iX. Magnetic resonance imaging of the thoracic spine revealed 2 metastatic foci in Th Viii, iX. Planar scintigraphy with 99mTc-pyrophosphate and CT performed 6 months after injection of 99mTc-ADAPT6 revealed previously described foci in the projection of the thoracic spine (Th Viii, iX) and 5 ribs on the right along the mid-clavicular line. Conclusion. The results demonstrated during the study suggest that 99mTc-ADAPT6 is a promising tracer for molecular imaging of tumor foci with overexpression of the Her2/neu receptor in breast cancer patients.