⁶⁸Ga-PSMA-11 PET/CT in a patient with non-PSA-secreting undifferentiated prostate cancer before and after treatment with cabozantinib

Excerpt

A 47-year-old man was diagnosed 3 years previously with a metastatic poorly differentiated non-neuroendocrine prostate adenocarcinoma, Gleason score 9, with low initial prostate-specific antigen (PSA) level (4.5 ng/mL). Multiple therapeutic lines were employed: docetaxel, androgen-deprivation therapy, abiraterone, cabazitaxel, cyclophosphamide and carboplatin. The patient presented with intense left iliac bone pain, a nearly undetectable PSA level and a significant increase in carcinoembryonic antigen (CEA, 140 ng/mL). ⁶⁸Ga-PSMA PET/CT performed at that time point demonstrated an extensive [1] demonstrated extensive metastatic disease with prostate-specific membrane antigen (PSMA) overexpression in lymph nodes, lungs, liver and bone lesions, especially the left iliac bone (a), with substantial involvement of adjacent soft tissues (b). The tumour board recommended trying cabozantinib (40 mg/day) [2], a multikinase inhibitor, obtained for use on compassionate grounds. A good clinical response with cessation of opioids was observed 3 months later, but CEA had continued to increase (377 ng/mL). ⁶⁸Ga-PSMA-11 PET/CT demonstrated an important decrease in size and PSMA expression of most metastases (d). However, new metastatic lesions were noted, mainly in the liver (c), suggesting resistant clone selection. …