Efficacy, Patient-Reported Outcomes (PROs), and Tolerability of the Changing Therapeutic Landscape in Patients with Metastatic Prostate Cancer (MPC): A Systematic Literature Review

ObjectiveNew therapies have attempted to improve on efficacy outcomes observed with docetaxel in patients with metastatic prostate cancer (MPC) who are hormone-therapy refractory or castration-resistant. In addition to the efficacy, patient-reported outcomes (PROs) and tolerability need to be assessed to define treatment benefit, as PROs measure the patient’s subjective experience and can be correlated with hard outcomes. The main objective of this study was to evaluate the survival benefit of new therapies and secondary efficacy-related outcomes. Assessment of the number of studies reporting PROs and tolerability was also conducted.MethodsA predefined search strategy was conducted on major academic/governmental databases and conference proceedings (2007–2011). Exclusion criteria were applied.ResultsOf 77 studies identified, 26 (34%) evaluated survival as an end point; 14 (18%) assessed PROs/tolerability. In chemotherapy-naive patients (no/minimal symptoms), median overall survival (OS) was 26 months for sipuleucel-T. In relapsed patients, the survival benefit of cabazitaxel/abiraterone was 15 months and that of enzalutamide was 18 months. Denosumab prolonged time to first on-study skeletal-related event (20.7 months denosumab, 17.1 months zoledronic acid; P = 0.0002, noninferiority; P = 0.008, superiority). Similar benefit was documented with radium-223, a new bone-targeted α-particle–emitting radiopharmaceutical. Radium-223 also significantly improved the OS (two-sided P = 0.00185). Specific to PROs, they were incorporated primarily as secondary end points, and improvements in pain response (most commonly evaluated) were variable among the agents. Last, the therapies were associated with unique toxicities requiring careful consideration.ConclusionsThe results of this review demonstrate that the therapeutic landscape of MPC has changed dramatically and many therapies in MPC now show OS improvements of about 4 months in the postdocetaxel setting.