During cancer progression, malignant cells undergo epithelial-mesenchymal transitions (EMT) and mesenchymal-epithelial transitions (MET) as part of a broad invasion and metastasis program. We previously observed MET events among lung metastases in a preclinical model of prostate adenocarcinoma that suggested a relationship between epithelial plasticity and metastatic spread. We thus sought to translate these findings into clinical evidence by examining the existence of EMT in circulating tumor cells (CTC) from patients with progressive metastatic solid tumors, with a focus on men with castration-resistant prostate cancer (CRPC) and women with metastatic breast cancer. We showed that the majority (>80%) of these CTCs in patients with metastatic CRPC coexpress epithelial proteins such as epithelial cell adhesion molecule (EpCAM), cytokeratins (CK), and E-cadherin, with mesenchymal proteins including vimentin, N-cadherin and O-cadherin, and the stem cell marker CD133. Equally, we found that more than 75% of CTCs from women with metastatic breast cancer coexpress CK, vimentin, and N-cadherin. The existence and high frequency of these CTCs coexpressing epithelial, mesenchymal, and stem cell markers in patients with progressive metastases has important implications for the application and interpretation of approved methods to detect CTCs. Mol Cancer Res; 9(8); 997–1007. ©2011 AACR.

PURPOSE: Androgen receptor splice variant 7 (AR-V7) results in a truncated receptor, which leads to ligand-independent constitutive activation that is not inhibited by anti-androgen therapies, including abiraterone or enzalutamide. Given that previous reports suggested that circulating tumor cell (CTC) AR-V7 detection is a poor prognostic indicator for the clinical efficacy of secondary hormone therapies, we conducted a prospective multicenter validation study. PATIENTS AND METHODS: PROPHECY ( ClinicalTrials.gov identifier: NCT02269982) is a multicenter, prospective-blinded study of men with high-risk mCRPC starting abiraterone acetate or enzalutamide treatment. The primary objective was to validate the prognostic significance of baseline CTC AR-V7 on the basis of radiographic or clinical progression free-survival (PFS) by using the Johns Hopkins University modified-AdnaTest CTC AR-V7 mRNA assay and the Epic Sciences CTC nuclear-specific AR-V7 protein assay. Overall survival (OS) and prostate-specific antigen responses were secondary end points. RESULTS: We enrolled 118 men with mCRPC who were starting abiraterone or enzalutamide treatment. AR-V7 detection by both the Johns Hopkins and Epic AR-V7 assays was independently associated with shorter PFS (hazard ratio, 1.9 [95% CI, 1.1 to 3.3; P = .032] and 2.4 [95% CI, 1.1 to 5.1; P = .020], respectively) and OS (hazard ratio, 4.2 [95% CI, 2.1 to 8.5] and 3.5 [95% CI, 1.6 to 8.1], respectively) after adjusting for CTC number and clinical prognostic factors. Men with AR-V7–positive mCRPC had fewer confirmed prostate-specific antigen responses (0% to 11%) or soft tissue responses (0% to 6%). The observed percentage agreement between the two AR-V7 assays was 82%. CONCLUSION: Detection of AR-V7 in CTCs by two blood-based assays is independently associated with shorter PFS and OS with abiraterone or enzalutamide, and such men with mCRPC should be offered alternative treatments.

Purpose: To develop a prognostic model and nomogram using baseline clinical variables to predict death among men with metastatic hormone-refractory prostate cancer (HRPC). Experimental Design: TAX327 was a clinical trial that randomized 1,006 men with metastatic HRPC to receive every three week or weekly docetaxel or mitoxantrone, each with prednisone. We developed a multivariate Cox model and nomogram to predict survival at 1, 2, and 5 years. Results: Ten independent prognostic factors other than treatment group were identified in multivariate analysis: (a) presence of liver metastases [hazard ratio (HR), 1.66; P = 0.019], (b) number of metastatic sites (HR, 1.63 if ≥2 sites; P = 0.001), (c) clinically significant pain (HR, 1.48; P < 0.0001), (d) Karnofsky performance status (HR, 1.39 if ≤70; P = 0.016), (e) type of progression (HR, 1.37 for measurable disease progression and 1.29 for bone scan progression; P = 0.005 and 0.01, respectively), (f) pretreatment prostate-specific antigen (PSA) doubling time (HR, 1.19 if <55 days; P = 0.066), (g) PSA (HR, 1.17 per log rise; P < 0.0001), (h) tumor grade (HR, 1.18 for high grade; P = 0.069), (i) alkaline phosphatase (HR, 1.27 per log rise; P < 0.0001), and (j) hemoglobin (HR, 1.11 per unit decline; P = 0.004). A nomogram was developed based on this multivariate model and validated internally using bootstrap methods, with a concordance index of 0.69. Conclusions: This multivariate model identified several new independent prognostic factors in men with metastatic HRPC, including PSA doubling time, and led to the successful development of a clinically applicable nomogram. External prospective validation may support the wider use of this prognostic baseline model for men with HRPC treated with chemotherapy.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. In primary analysis, enzalutamide plus androgen deprivation therapy (ADT) improved radiographic progression-free survival (rPFS) in patients with metastatic hormone-sensitive prostate cancer (mHSPC); however, overall survival data were immature. In the phase III, double-blind, global ARCHES trial (ClinicalTrials.gov identifier: NCT02677896 ), 1,150 patients with mHSPC were randomly assigned 1:1 to enzalutamide (160 mg once daily) plus ADT or placebo plus ADT, stratified by disease volume and prior docetaxel use. Here, we report the final prespecified analysis of overall survival (key secondary end point) and an update on rPFS, other secondary end points, and safety. After unblinding, 180 (31.3%) progression-free patients randomly assigned to placebo plus ADT crossed over to open-label enzalutamide plus ADT. As of May 28, 2021 (median follow-up, 44.6 months), 154 of 574 patients randomly assigned to enzalutamide plus ADT and 202 of 576 patients randomly assigned to placebo plus ADT had died. Enzalutamide plus ADT reduced risk of death by 34% versus placebo plus ADT (median not reached in either group; hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P < .001). Enzalutamide plus ADT continued to improve rPFS and other secondary end points. Adverse events were generally consistent with previous reports of long-term enzalutamide use. In conclusion, enzalutamide plus ADT significantly prolongs survival versus placebo plus ADT in patients with mHSPC.

Purpose It is currently unclear if early prostate-specific antigen (PSA) or pain improvements are adequate surrogates for overall survival in men with metastatic hormone-refractory prostate cancer (HRPC). Here we examined various degrees of PSA decline and pain response as surrogates for the survival benefit observed in the TAX327 trial. Patients and Methods In the TAX327 trial, 1,006 men with HRPC were randomly assigned to receive docetaxel in two schedules, or mitoxantrone, each with prednisone: 989 men provided data on 3-month PSA decline. Surrogacy was examined for post-treatment changes in PSA and pain response using Cox proportional hazards models to calculate the proportion of treatment effect (PTE) explained by each potential surrogate. Results A ≥ 30% PSA decline within 3 months of treatment initiation provides the highest degree of surrogacy, with a PTE of 0.66 (95% CI, 0.23 to 1.0), and was associated with a hazard ratio (HR) of 0.50 (95% CI, 0.43 to 0.58) for overall survival after adjusting for treatment effect. Introduction of a ≥ 30% PSA decline is predictive of survival regardless of treatment arm. Other changes in PSA or PSA kinetics, PSA normalization, and pain responses were highly prognostic but weaker surrogates for survival. Conclusion In the TAX327 trial, a PSA decline of ≥ 30% within 3 months of chemotherapy initiation had the highest degree of surrogacy for overall survival, confirming data from the Southwest Oncology Group 9916 trial. However, given the wide CIs around the estimate of this moderate surrogate effect, overall survival should remain the preferred end point for phase III trials of cytotoxic agents in HRPC.