According to the findings, in comparison with watchful waiting the drug can prolong overall survival and delay the occurrence of disease complications. In men aged 75 years or older, IQWiG sees an indication of a major added benefit. There is also an indication of an added benefit in younger men; however, the extent is rated as "considerable."
Approval study terminated prematurely
The assessment was based on a randomized controlled trial (PREVAIL), which was the approval study for the indication described above. In this study, patients received either enzalutamide or a placebo, while the hormone-blocking medication was continued in all patients. In each study arm, treatment was continued until either the disease worsened (progression) or safety concerns arose, for example, because toxicity was too high.
As the interim analysis planned for the outcome "overall survival" had already shown good efficacy of enzalutamide, this was considered as the final Analysis.
Survival advantage depends on age
The difference in overall survival is statistically significant between the two study arms. However, as the further analysis of the data shows, this advantage is age dependent. It is greater in older men (75 years or more) than in younger ones. In each case, the IQWiG researchers derive an indication of an added benefit from these results, albeit with a different extent (major or minor).
Bone-related complications occur later
The study data also showed relevant group differences in favour of enzalutamide for other outcomes. For instance, bone-related complications occurred later in patients receiving enzalutamide than in those receiving placebo. IQWiG sees an indication of an added benefit here.
In addition, it took longer until opiates were used, that is, severe pain occurred later in patients receiving enzalutamide. This also applies to the occurrence of side effects (severe and serious adverse events) and the discontinuation of treatment due to side effects. Health-related quality of life also deteriorated later.