The phase 3 PROSPER trial has showed a statistically significant improvement in metastasis-free survival ( MFS ) with Enzalutamide ( Xtandi; n = 933 ) versus placebo ( n = 468 ) in asymptomatic men with non-metastatic castration-resistant prostate cancer ( M0 CRPC ) and prostate-specific antigen doubling time less than or equal to 10 months.
Functional Assessment of Cancer Therapy–Prostate ( FACT-P ) and Brief Pain Inventory - Short Form ( BPI-SF ), were used to assess health-related quality of life ( HRQoL ) and pain at baseline and every 16 weeks during treatment.
Pain progression was defined as greater than or equal to 2 points in pain severity items and mean scores increase from baseline; HRQoL improvement / deterioration as an increase / decrease from baseline using pre-established thresholds for clinically meaningful difference.
Time to first confirmed ( at two consecutive visits ) and unconfirmed HRQoL deterioration / pain progression were assessed using Kaplan-Meier estimates and Cox proportional hazards models under censoring not at random assumption.
Baseline characteristics and scores were similar between arms with low pain ( median 0 ) and high HRQoL ( median FACT-P total score, 121 ).
Decrease in attrition rate was greater in placebo versus Enzalutamide mainly due to disease progression ( 53% versus 68% at week 49, respectively ).
Most patients reported no change or improvement in HRQoL. Proportion of patients with pain progression at week 49 was similar between Enzalutamide ( 11–20% ) and placebo ( 14–21% ).
Lower risk of pain progression was observed with Enzalutamide versus placebo in the confirmed analysis ( hazard ratio [ HR ] 0.78–0.93; p more than 0.05 ).
Nominal statistically significant lower risk of deterioration was observed with Enzalutamide for FACT-P total, FACT Advanced Prostate Symptom Index, prostate cancer subscale ( PCS ), and emotional well-being ( EWB ) in the confirmed ( HR=0.75, 0.77, 0.77, 0.69, respectively; p less than 0.05 ) and for PCS and EWB in the unconfirmed ( HR=0.82, 0.80, respectively; p less than 0.05 ) analyses.
In PROSPER trial, Enzalutamide significantly delayed metastasis-free survival versus placebo without worsening HRQoL and significantly reduced the risk of clinically meaningful HRQoL deterioration in several FACT-P domains.
Pain progression was similarly low in both arms. ( Xagena )
Source: ASCO ( American Society of Clinical Oncology ) Meeting, 2018