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Assessment of total, PTEN and AR-V7+ circulating tumor cells count by flow cytometry in patients with metastatic castration-resistant prostate cancer receiving enzalutamide. In this study men with metastatic castration resistant prostate cancer, scheduled to start enzalutamide, were assessed for circulating tumor cells count and molecular characterization (total, PTEN and AR-V7+ circulating tumor cells count) by the use of flow cytometry. We found that flow cytometry could be used to enumerate circulating tumor cells, but also to assess molecular biomarkers on their surface. Introduction. Metastatic castration-resistant prostate cancer (mCRPC) is a deadly disease. Enzalutamide is an oral second-generation anti-androgen that is active in mCRPC. Circulating tumor cells (CTC) count correlates with overall survival (OS) in mCRPC, whereas detection of the androgen-receptor splice variant 7 (AR-V7) in CTC predicts poor response to oral second-generation anti-androgens. Also, loss of PTEN (phosphatase and tensin homolog) in CTC is a biomarker of poor prognosis in mCRPC. Patients and methods. In this translational study, we employed flow cytometry to assess total, PTEN-, and AR-V7+ CTC count per 7.5 mL of whole blood in a prospective cohort of patients with mCRPC receiving enzalutamide. Results. CTCs were assessed in a total of 45 men with mCRPC at baseline and at 12 weeks. Overall, CTC, PTEN- CTC, and AR-V7+ CTC detection rate was high, at baseline, with 84.4%, 71.1%, and 51.1% of samples showing at least 1 cell/7.5-mL blood, respectively, and after 3 months, with 93.3%, 64.4%, and 77.7% of samples showing at least 1 cell/7.5-mL blood, respectively. Median radiographic progression-free survival (rPFS) and OS were 6 (95% confidence interval [CI], 5.6-9) and 14.3 (95% CI, 12.8-20.3) months, respectively. Median (interquartile range) total CTC count at baseline was 5 (3; 8), whereas median (interquartile range) PTEN- CTC count was 2 (0; 4) and median (interquartile range) AR-V7+ CTC count was 1 (0; 3). At baseline, ≥ 5 versus < 5 total CTC count was associated with worse rPFS (hazard ratio [HR], 2.35; 95% CI, 1.14-4.84; P = .021) and OS (HR, 3.08; 95% CI, 1.45-6.54; P = .003), whereas ≥ 2 versus < 2 PTEN- CTC count was associated with worse rPFS (HR, 3.96; 95% CI, 1.8-8.72; P = .001) and OS (HR, 2.36; 95% CI, 1.12-5; P = .025). Finally, ≥ 1 versus < 1 AR-V7+ CTC count was also associated with worse rPFS (HR, 5.05; 95% CI, 2.4-10.64; P < .001) and OS (HR, 2.25; 95% CI, 1.1-4.58; P = .026). Conclusions. Despite multiple limitations, including the small sample size, our preliminary study suggests that assessment of CTC via flow cytometry may provide potentially useful prognostic and predictive information in advanced prostate cancer. Further studies are warranted. Micro-Abstract: In this study, men with metastatic castration-resistant prostate cancer, scheduled to start enzalutamide, were assessed for circulating tumor cell count and molecular characterization (total, PTEN-, and AR-V7+ circulating tumor cell count) by the use of flow cytometry. We found that flow cytometry could be used to enumerate circulating tumor cells, but also to assess molecular biomarkers on their surface. [ABSTRACT FROM AUTHOR]

Although both docetaxel and androgen-receptor-axis-targeted (ARAT) agents have yielded survival improvements in combination with androgen deprivation therapy (ADT) compared to ADT alone in metastatic castration-sensitive prostate cancer (mCSPC) patients, the optimal therapeutic choice remains to be established. We analyzed estimates of the hazard ratios for death (OS-HRs) in patients treated in the first-line setting enrolled in the GETUG-AFU15, CHAARTED, STAMPEDE, LATITUDE, ENZAMET, and TITAN trials. Overall, men with mCSPC receiving ADT with vs. without either an ARAT agent or docetaxel as first-line systemic therapy showed a pooled OS-HR of 0.69 (95 % CI: 0.61−0.78), with significant heterogeneity (p = 0.045, I2 = 52.5 %). Network meta-analysis showed an OS-HR in patients receiving an ARAT agent vs. docetaxel of 0.78 (95 %CI: 0.67−0.91). In conclusion, the evidence analysed indicates that an ARAT agent may provide improved OS outcomes compared to docetaxel. Prospective randomized trials are warranted. [ABSTRACT FROM AUTHOR]

Both docetaxel and androgen-receptor-axis-targeted (ARAT) agents are approved in metastatic castration-sensitive prostate cancer (mCSPC) patients. Predictive factors of therapy efficacy are lacking. We included articles reporting data about randomized-controlled clinical trials (RCTs) testing an ARAT agent plus ADT vs. ADT. We aimed to obtain pooled estimates of efficacy outcomes and assess differences in pooled estimates of efficacy outcomes between sub-groups. A total of 5427 mCSPC patients enrolled in five RCTs were evaluable for OS (Overall Survival) and PFS (Progression-free survival). Pooled OS-HR (Hazard Ratio) was 0.66 (95 % CI: 0.60−0.74), while pooled PFS-HR was 0.46 (95 % CI: 0.40−0.53). Combined treatment with docetaxel was associated with differential OS outcomes, while tumor volume according to the CHAARTED criteria and visceral metastasis were associated with differential PFS outcomes. Our results add evidence that ARAT agents improve OS in mCSPC and discourage their combined use with docetaxel in this setting. [ABSTRACT FROM AUTHOR]