The recently published phase II prospective SWITCH trial evaluated whether patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone acetate could benefit from a 'steroid switch' from prednisone to dexamethasone. A total of 26 patients, both chemonaïve (14 patients) or pretreated with docetaxel (12 patients), with biochemical and/or limited radiological progression, were enrolled in this trial. Primary endpoint was prostate specific antigen (PSA) 30 defined as the proportion of patients with a PSA level decline 30% or more after 6 weeks of treatment with abiraterone acetate + dexamethasone. Secondary endpoints were: a PSA50 rate (defined as the proportion of patients with PSA decline of 50% or more after 12 weeks on abiraterone acetate + dexamethasone), biochemical and radiological progression-free survival (bPFS and rPFS, respectively), benefit from subsequent treatment and identification of biomarkers of response. Primary endpoint was reached in 46.2% of patients (12 patients), and two patients had an objective partial response on computed tomography scan. Median bPFS and rPFS were 5.3 months and 11.8 months. We present a case series of 11 patients who were consecutively treated with a steroid switch at our institution from January 2016 to August 2018 to investigate if this strategy could be used in a 'real-life' setting. We observed a PSA30 response in two patients (18%), median bPFS was 4.77 months (95% confidence interval [CI] 2.5-14.6) and median rPFS was 7.2 months (95% CI 3.8-15.5). Seven patients had a radiological stable disease as best response to steroid switch. Three patients were being still treated with abiraterone acetate + dexamethasone at data cut-off time. Our case series confirms that switching from prednisone to dexamethasone during abiraterone acetate treatment produces biochemical and radiological responses in both a predocetaxel and a postdocetaxel setting, providing a clinical benefit in mCRPC patients. However, to date, there is no clear indication as to which patient could benefit most from this kind of strategy.
Therapeutic advances in urology. 2019 Jun 11*** epublish ***
Elisa Zanardi, Davide Soldato, Maria Maddalena Latocca, Carlo Cattrini, Francesco Boccardo
Academic Unit of Medical Oncology, IRCCS San Martino Polyclinic Hospital, Largo R. Benzi 10, Genoa, 16132, Italy., Academic Unit of Medical Oncology, IRCCS San Martino Polyclinic Hospital, Genoa, Italy.