The AQUARiUS study evaluated the quality of life (QoL) of metastatic castration-resistant prostate carcinoma (mCRPC) patients and concluded that abiraterone is better tolerated. However, a thorough assessment of the results is important, as they have a degree of complexity.
Abiraterone and enzalutamide are equally recommended side by side by the current guidelines on prostate carcinoma. So far, there is no really evident criterion for recommending one active component over the other. However, the AQUARiUS study evaluated the quality of life (QoL) of the patients and concluded that abiraterone is better tolerated by metastatic castration-resistant prostate carcinoma (mCRPC) patients. However, it is not quite as simple as that, as a closer inspection of the study indicates.
The 12-month observational study AQUARiUS1 included a total of 226 patients who were treated with either abiraterone or enzalutamide due to a diagnosed metastatic castration-resistant prostate cancer (mCRPC). The most important study component was the patient-reported outcome in the course of treatment. Data were collected at four appointments at three-month intervals using validated questionnaires.
The results showed that the treatment with abiraterone lasted 38.3 weeks and 38.7 weeks with enzalutamide. During this time, significant improvements occurred in 18 of 28 partial aspects of patient assessment. Nine of these improvements were particularly strong for abiraterone. Above all, cognition, fatigue, appetite, and nausea were significantly improved with abiraterone. About 69% of the patients suffered from one or more side effects with abiraterone, compared to 77% with enzalutamide.
The study authors concluded from their data that abiraterone is superior to enzalutamide in patients with mCRPC with regard to QoL. Therefore, they consider that in addition to clinical aspects, a patient assessment must be taken into account to a greater extent when making therapy decisions. In patients undergoing treatment of abiraterone plus prednisolone, the men had fewer cognitive impairments or fatigue, an effect that also occurred early after the start of therapy.
The study discussion does not address three essential aspects. Firstly, it is a non-randomized observational study, and secondly, the study was financed by a pharmaceutical company that distributes abiraterone acetate for the treatment of prostate cancer.
However, it is important to note that the average age of the study population in the AQUARiUS study was 72 years for both treatment regimes. From other studies, it is already well known that abiraterone could be beneficial in older study populations. Especially multimorbid prostate cancer patients in older age groups seem to benefit from abiraterone.
This is again confirmed by a recent study by Khalaf and colleagues2, who have shown that the QoL of older patients (> 75 years) in particular is influenced more favorably by abiraterone than by enzalutamide. In contrast, there was no significant difference between the two treatments with regard to QoL in a younger patient population (< 75 years).
Abiraterone and enzalutamide appear to be equivalent in the treatment of mCRPC according to the current study, and also according to the current European Association of Urology (EAU) guidelines also convey. However, there are differences especially in older patients > 75 years of age, who are mostly multimorbid and have a higher risk of cognitive impairment due to their age.
According to studies, this group of patients could actually benefit more from abiraterone treatment, which does not impair cognition as much as, for example, enzalutamide in this age group, which is usually already "previously damaged".
In my opinion, the data of the AUQARUiUS study do not provide a general recommendation for abiraterone instead of enzalutamide. Rather, the use of both drugs should continue to be critically examined from case to case and the patient should be helped to choose the most tolerable option.
Sources:
1. Thiery-Vuillemin A et al. Eur Urol 2019: https://doi.org/10.1016/j.eururo.2019.09.019
2. Khalaf DJ et al., Eur Urol 2019: https://doi.org/10.1016/j.eururo.2018.12.015