Patients with metastatic castrate resistant prostate cancer treated with enzalutamide (ENZ) may be more likely to experience central nervous system adverse events and fatigue than those who receive a combination of abiraterone acetate and prednisone (AA+P), according to the results of a poster presented at the American Society of Clinical Oncology Annual Meeting (June 3-7, 2016; Chicago, IL).
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The treatment of prostate cancer has significantly improved with the advent of new therapeutic options such as AA+P and ENZ, but these regimens also carry concerns regarding adverse events of the CNS, fatigue, and pain, which can lead to dose reductions. Therefore, researchers led by Ajay Behl, PhD, associate director at Janssen Scientific Affairs in Horsgam, PA, conducted a retrospective analysis of records contained in the Marketscan insurance claims database to compare the occurrence of adverse events in patients treated with AA+P or ENZ for prostate cancer.
A total of 2196 patients prescribed AA+P and 807 patients prescribed ENZ were identified, but researchers re-weighted the population to account for the inverse probability of treatment weighting. After that was completed, each group contained ~1500 patients (AA+P = 1493 and ENZ = 1510).
At 12 months follow-up, 30.3% of patients receiving AA+P had a CNS event versus 37.5% in those treated with ENZ. Similarly, the rate of fatigue was also higher than the ENZ arm of the study than it was in the AA+P arm (28% vs 25%, respectively). As a result, more patients who were treated with ENZ ended up having a dose reduction than those on AA+P (20% vs 13.6%).
Pain was also more common in the ENZ group than it was in the AA+P group (15.3% vs 12.9%, respectively), though the difference was not statistically significant.
Researchers concluded that patients with metastatic castrate resistant prostate cancer treated with ENZ were more likely to experience CNS and fatigue adverse events that resulted in treatment dose reduction than those treated with AA+P.