Theranostic Advances in Breast Cancer in Nuclear Medicine

Abstract

The implication of 'theranostic' refers to targeting an identical receptor for diagnostic and therapeutic purposes, by the same radioligand, simultaneously or separately. In regard to extensive efforts, many considerable theranostic tracers have been developed in recent years. Emerging evidence strongly demonstrates the tendency of nuclear medicine towards therapies based on a diagnosis. This review is focused on the examples of targeted radiopharmaceuticals for the imaging and therapy of breast cancer.

Keywords: imaging; radiopharmaceutical; theranostic; therapy.

Figure 1

The general concept of theranostic radiopharmaceuticals. A radionuclide is combined with a targeting vector (Binding molecule). The choice of radionuclide defines the purpose of the radiopharmaceutical. γ⁻ or β⁺-emitters are used for diagnostics while β⁻- and α-emitters are applied in therapy. The targeting vector guides the radiopharmaceutical to its specific target (e.g., receptors). To combine the radionuclide with a target vector without reducing its affinity to its target, normally, depending on the type of radionuclide (e.g., metal, non-metal), linking structures (linker molecules) are necessary.

Figure 2

PET-Scan of [18F]FDG (left) and [⁸⁹Zr]Zr-trastuzumab (right) of a patient with a [⁸⁹Zr]Zr-trastuzumab scan considered HER2-positive (Figure adapted from Bensch et al. [53] Creative Commons Attribution 4.0 International License).

Figure 3

Patient with a mucinous carcinoma of the right breast with low ER/PR-expression. CT (left); ⁶⁸Ga-RM2-PET (middle); fusion images (right); primary tumour indicated by white arrow; lymph node metastasis indicated by red arrows. (Figure unmodified from Stykow et al. [79] Creative Commons Attribution 4.0 International License).

Figure 4

Chemical structure of DOTA.SA.FAPI. PET-Scan of [¹⁸F]FDG (left), [⁶⁸Ga]Ga-DOTA.SA.FAPI (middle) and [¹⁷⁷Lu]Lu- DOTA.SA.FAPI (right) of a patient with HER2-positive, (ER and PR)-negative histopathology (Figure adapted from Ballal et al. [109] Creative Commons Attribution 4.0 International License).