Below the Belt Award

Lu PSMA therapy is a new therapy for men with metastatic castrate resistant prostate cancer (mCRPC) that has been shown to be better tolerated than, and equally effective to cabazitaxel chemotherapy (TheraP). However, not all men respond to the treatment identically, with some men demonstrating dramatic responses and others progressing early. Personalising treatment for the individual requires response bio-markers that can accurately measure dynamic changes in treatment response, allowing intensification or de-intensification of treatment. In men with exceptional response, treatment can be paused, while in men with cancer growth despite treatment, treatment can be intensified or changed. Currently we use PSA, CT scans and bone scans to determine whether a man is responding well to treatment. However, Lu PSMA treatment emits a gamma wave that enables a whole-body image evaluating all tumour sites after each therapy injection (24 hours); this picture is called a SPECT scan. Work on the LUPIN trial at St Vincent’s has shown that any increase in tumour volume on Lu PSMA SPECT predicted cancers that were not responding to treatment, even when the PSA had not yet risen. The concept of using images from the therapy itself (SPECT imaging) – is unique to theranostics approaches like Lu PSMA. The potential for these SPECT scans to provide dynamic treatment response information has not been fully assessed. While this initial evaluation shows that Lu PSMA SPECT has the potential to be an effective response biomarker, many questions remain to properly validate its role and optimise its potential uses. ANZUP has unique clinical trials in Lu PSMA with stored SPECT data and the associated treatment response data for each patient. Analysing these data would allow us to fully evaluate the role and benefit of SPECT as an interim response biomarker – potentially further improving the lives of patients through better, faster clinical decision making.