Circulating Tumor Cells in a Phase 3 Study of Docetaxel and Prednisone with or without Lenalidomide in Metastatic Castration-resistant Prostate Cancer

摘要

Elevated circulating tumor cell (CTC) blood levels (>= 5 cells/7.5 ml) convey a negative prognosis in metastatic castration-resistant prostate cancer but their prognostic significance in patients receiving chemotherapy is uncertain. The association between CTC counts (at baseline or after treatment), overall survival (OS), and response to docetaxelwith lenalidomidewas evaluated in a 208-patient subset fromtheMAINSAIL trial, which compared docetaxel-prednisone-lenalidomide and docetaxel-prednisoneplacebo inmetastatic castration-resistant prostate cancer patients. Baseline CTCswere < 5 cells/7.5 ml blood in 87 (42%) patients and >= 5 cells/7.5 ml in 121 (58%) patients. Neither tumor response nor prostate-specific antigen response correlated with baseline CTCs. However, CTC count >= 5 cells/7.5 ml was significantly associated with lower OS (hazard ratio: 3.23, p = 0.0028). Increases in CTCs from < 5 cells/7.5 ml to >= 5 cells/7.5 ml after three cycleswere associated with significantly shorter OS (hazard ratio: 5.24, p = 0.025), whereas CTC reductions from >= 5 cells/7.5 ml to >= 5 cells/7.5 ml were associated with the best prognosis (p = 0.003).