Triple negative breast cancer (TNBC) is the most aggressive breast cancer and is difficult to treat with current therapies, as TNBC does not have specific targeted therapies. Chemotherapy has so far been the only treatment option. However, EpCAM expression that occurs on the surface of cancer cells is now a suggested target for TNBC.
Radiolabelling of aptamers could provide a unique strategic approach to successfully treat TNBC and their metastases. In particular, 68Gallium (Positron emission gamma-ray emitter only) and 177Lutetium (emits both gamma-rays and beta-particles, simultaneously) provide promise in diagnostic and therapeutic fields, respectively, if applied to TNBC. Additionally, radiolabelled aptamers can be effective at targeting TNBC metastases, especially bone and brain metastases.
68GaDOTA labelled onto Octreotate has been used as a diagnostic agent for neuroendocrine metastatic tumors and not demonstrated complication or toxicity. The same 68GaDOTA can be used with an aptamer linkage to target TNBC and their small metastatic sites.
177Lu has convincingly demonstrated theranostic success in prostate cancer patients by PSMA binding. Beta particles emitted by 177 Lu extends only millimeters in human tissue and provides a therapeutic radiation dose, while, the emitted gamma-rays can be used for diagnostic imaging. By creating and using a 177LuDOTA-EpCAM conjugate, there is great possibility to achieve a theranostic effect for TNBC patients.
Aptamers are, however, presented as a superior alternative to antibodies due to their high binding affinity and pH stability. As aptamer linkage with radiolabelled DOTA can reach small (and possibly undetectable) metastatic sites easily because of their low molecular weight, high specificity and small size.
Radiolabelled aptamer conjugates can provide positive hope for future diagnosis and treatment and will start a new era in oncology. Due to complications that exist with current approved therapies – and if proven successful – radiolabelled aptamers will be used frequently in our clinical environment as a theranostic tool.