Neuroendocrine and small-cell prostate cancer

Neuroendocrine prostate cancer includes rare de novo small-cell carcinoma and, far more often, treatment-emergent disease that arises when adenocarcinoma under prolonged androgen receptor blockade switches lineage, typically with combined loss of RB1 and TP53, PTEN loss, MYCN or AURKA amplification and loss of androgen receptor and PSA expression. It is suspected when disease progresses with a low or flat PSA, visceral or lytic bone metastases, raised chromogranin, neuron-specific enolase or lactate dehydrogenase, or FDG-avid but PSMA-negative lesions, and confirmed by biopsy showing small-cell morphology or synaptophysin and chromogranin staining. There is no approved therapy specific to it: platinum with etoposide, or carboplatin with docetaxel for mixed histology, is standard, with response rates of about half but brief duration, and androgen deprivation is usually continued. Immunotherapy adds little outside mismatch repair deficiency. DLL3 is expressed in most neuroendocrine prostate cancers, and the DLL3 T-cell engager tarlatamab, approved for small-cell lung cancer, is in trials here; EZH2 inhibitors and aurora kinase inhibitors are being tested against the lineage switch itself.