Enzalutamide Reduces Oxycodone Exposure in Men with Prostate Cancer.

BACKGROUND AND OBJECTIVE: Up to 90% of patients with castration-resistant prostate cancer (CRPC) will develop symptomatic bone metastases requiring pain medication, with opioids being the mainstay of therapy in treating moderate and severe pain. Enzalutamide is an androgen receptor antagonist for the treatment of CRPC and a strong inducer of cytochrome P450 (CYP)3A4. Hereby, enzalutamide potentially reduces the exposure of oxycodone, an opioid metabolized by CYP3A4 and CYP2D6. Our objective was to evaluate the potential drug-drug interaction of enzalutamide and oxycodone. METHODS: A prospective, nonrandomized, open-label, two-arm parallel study was performed. All patients received a single dose of 15 mg normal-release oxycodone. Patients in the enzalutamide arm (ENZ-arm) received enzalutamide 160 mg once daily. Plasma concentrations of oxycodone and its metabolites were quantified using a validated liquid chromatography with tandem mass spectrometry (LC-MS/MS) method. RESULTS: Twenty-six patients (13 ENZ-arm; 13 control arm) were enrolled in the study. Enzalutamide decreased the mean AUC0-8 h and Cmax of oxycodone with, respectively, 44.7% (p < 0.001) and 35.5% (p = 0.004) compared with the control arm. The AUC0-8 h and Cmax of the active metabolite oxymorphone were 74.2% (p < 0.001) and 56.0% (p = 0.001) lower in the ENZ-arm compared with the control arm. In contrast, AUC0-8 h and Cmax of the inactive metabolites noroxycodone and noroxymorphone were significantly increased by enzalutamide. CONCLUSION: Co-administration of enzalutamide significantly reduced exposure to oxycodone and its active metabolite oxymorphone in men with prostate cancer. This should be taken into account when prescribing enzalutamide combined with oxycodone.

Urinary incontinence and erectile dysfunction in patients with localized or locally advanced prostate cancer: A nationwide observational study.

BACKGROUND: Although urinary adverse events after treatment of prostate cancer (CaP) are common, population-based studies on functional outcomes are scarce. The aim of this study is to evaluate the occurrence of urinary incontinence (UI) and erectile dysfunction (ED) in daily clinical practice using a nationwide Dutch cohort of patients with localized or locally advanced CaP. BASIC PROCEDURES: Patients were invited to complete the EPIC-26 questionnaire before treatment (baseline) and at 12 and 24 months after diagnosis. We calculated the mean EPIC-26 domain scores, stratified by treatment modality (i.e., radical prostatectomy, external radiotherapy, and no active treatment), and the proportions of patients with UI (defined as ≥ 2 pads per day) and ED (defined as erections not firm enough for sexual intercourse). Logistic regression modeling was used to explore the factors related to UI and ED after surgery. MAIN FINDINGS: In total 1,759 patients participated in this study. Patients undergoing radical prostatectomy experienced clinically relevant worsening in the urinary incontinence domain. After excluding patients who reported UI at baseline, 15% of patients with prostatectomy reported UI 24 months after diagnosis. Only comorbidity was associated with UI in surgically treated patients. Regardless of treatment, patients reported a clinically significant reduced sexual functioning over time. Before treatment, 54% of patients reported ED. Among the 46% remaining patients, 87% of patients treated with radical prostatectomy reported ED 24 months after diagnosis, 41% after radiotherapy, and 46% in patients without active treatment. Bilateral nerve-sparing surgery was the only factor associated with ED after 24 months. PRINCIPAL CONCLUSIONS: UI and ED frequently occur in patients with localized and locally advanced CaP, in particular after radical prostatectomy. The higher occurrence rate of UI and ED, compared with clinical trial participants, supports the importance of real-world data, which can be used for local treatment recommendations and patient information, but also to evaluate effects of future initiatives, such as treatment centralization and research aimed at improving functional outcomes.

Prostate cancer: trends in incidence, survival and mortality in the Netherlands, 1989-2006.

BACKGROUND: Prostate cancer occurrence and stage distribution changed dramatically during the end of the 20th century. This study aimed to quantify and explain trends in incidence, stage distribution, survival and mortality in the Netherlands between 1989 and 2006. METHODS: Population-based data from the nationwide Netherlands Cancer Registry and Causes of Death Registry were used. Annual incidence and mortality rates were calculated and age-adjusted to the European Standard Population. Trends in rates were evaluated by age, clinical stage and differentiation grade. RESULTS: 120,965 men were newly diagnosed with prostate cancer between 1989 and 2006. Age-adjusted incidence rates increased from 63 to 104 per 100,000 person-years in this period. Two periods of increasing incidence rates could be distinguished with increases predominantly in cT2-tumours between 1989 and 1995 and predominantly in cT1c-tumours since 2001. cT4/N+/M+-tumour incidence rates decreased from 23 in 1993 to 18 in 2006. The trend towards earlier detection was accompanied by a lower mean age at diagnosis (from 74 in 1989 to 70 in 2006), increased frequency of treatment with curative intent and improved 5-year relative survival. Mortality rates decreased from 34 in 1996 to 26 in 2007. CONCLUSIONS: The increase of prostate cancer incidence in the early 1990s was probably caused by increased prostate cancer awareness combined with diagnostic improvements (transrectal ultrasound, (thin) needle biopsies), but not PSA testing. The subsequent peak since 2001 is probably attributable to PSA testing. The decline in prostate cancer mortality from 1996 onwards may be the consequence of increased detection of cT2-tumours between 1989 and 1995. Unfortunately, data on the use of PSA tests and other prostate cancer diagnostics to support these conclusions are lacking.