 Loss of PTEN is common in CRPC. Current data indicate that AZD8186 inhibits PI3K downstream signalling in PTEN deficient but not in PTEN proficient cells and hence POM and efficacy will need to be determined in tumours with PTEN protein loss. In future studies, paired biopsy tumour tissue will be accessible for assessment of POM and PTEN status, either bone metastases lymph node metastases, or within the prostate tumour. 