Safety: The risk of grade 3 or higher adverse events was similar across the 2 groups. Most common adverse events were known toxic effects of docetaxel therapy and were highest during the initial period when both groups received this therapy. These side effects progressively decreased after the initial period. The most common grade 3 or 4 adverse event was neutropenia, and its frequency was similar between the darolutamide and placebo groups (33.7% and 34.2%, respectively). The most frequently reported adverse events were alopecia, neutropenia, fatigue, and anemia and were similar between the groups. Adverse events of special significance, including fatigue, falls, fractures, and cardiovascular events, were also similar between the 2 groups. Adverse events causing deaths in each arm were low and similar (4.1% in the darolutamide group and 4.0% in the placebo group). The rates of discontinuation of darolutamide or placebo were similar (13.5% and 10.6%, respectively).
Conclusion: Among patients with mHSPC, overall survival was significantly longer among patients who received darolutamide plus ADT and docetaxel than among those who received ADT and docetaxel alone. This was observed despite a high percentage of patients in the placebo group receiving subsequent systemic therapy at the time of progression. The survival benefit of darolutamide was maintained across most subgroups. An improvement was also observed in the darolutamide arm in terms of key secondary end points. The adverse events were similar across the groups and were consistent with known safety profiles of ADT and docetaxel, and no new safety signals were identified in this trial.
Commentary
The results of the current study add to the body of literature supporting multi-agent systemic therapy in newly diagnosed mHSPC. Prior phase 3 trials of combination therapy using androgen-receptor pathway inhibitors, ADT, and docetaxel have shown conflicting results. The results from the previously reported PEACE-1 study showed improved overall survival among patients who received abiraterone with ADT and docetaxel as compared with those who received ADT and docetaxel alone.1 However, as noted by the authors, the subgroup of patients in the ENZAMET trial who received docetaxel, enzalutamide, and ADT did not appear to have a survival advantage compared with those who received ADT and docetaxel alone.2 The results from the current ARASENS trial provide compelling evidence in a population of prospectively randomized patients that combination therapy with darolutamide, docetaxel, and ADT improves overall survival in men with mHSPC. The survival advantage was maintained across subgroups analyzed in this study. Improvements were observed in regards to several key secondary end points with use of darolutamide. This benefit was maintained despite many patients receiving subsequent therapy at the time of progression. Importantly, there did not appear to be a significant increase in toxicity with triplet therapy. However, it is important to note that this cohort of patients appeared largely asymptomatic at the time of enrollment, with 70% of patients having an Eastern Cooperative Oncology Group performance status of 0.
Additionally, the average age in this study was 67 years, with only about 15% of the population being older than 75 years. In the reported subgroup analysis, those older than 75 years appeared to derive a similar benefit in overall survival, however. Whether triplet therapy should be universally adopted in all patients remains unclear. For example, there is a subset of patients with mHSPC with favorable- risk disease (ie, those with recurrent metastatic disease, node-only disease). In this population, the risk-benefit analysis is less clear, and whether these patients should receive this combination is not certain. Nevertheless, the results of this well-designed study are compelling and certainly represent a potential new standard treatment option for men with mHSPC. One of the strengths of this study was its large sample size that allowed for vigorous statistical analysis to evaluate the efficacy of darolutamide in combination with ADT and docetaxel.
Application for Clinical Practice
The ARASENS study provides convincing evidence that in men with mHSPC, the addition of darolutamide to docetaxel and ADT improves overall survival. This combination appeared to be well tolerated, with no evidence of increased toxicity noted. Certainly, this combination represents a potential new standard treatment option in this population; however, further understanding of which subgroups of men benefit from enhanced therapy is needed to aid in proper patient selection.
—Santosh Kagathur, MD, and Daniel Isaac, DO, MS
Michigan State University, East Lansing, MI