Symptomatic Skeletal Events and the Use of Bone Health Agents in a Real-World Treated Metastatic Castration Resistant Prostate Cancer Population: Results From the CAPRI-Study in the Netherlands.

BACKGROUND: Patients with metastatic castration resistant prostate cancer (mCRPC) are at risk of symptomatic skeletal events (SSE). Bone health agents (BHA, ie bisphosphonates and denosumab) and new life-prolonging drugs (LPDs) can delay SSEs. The aim of this study is to investigate the use of BHAs in relation to SSEs in treated real-world mCRPC population. PATIENTS AND METHODS: We included patients from the CAPRI registry who were treated with at least one LPD and diagnosed with bone metastases prior to the start of first LPD (LPD1). Outcomes were SSEs (external beam radiation therapy (EBRT) to the bone, orthopedic surgery, pathologic fracture or spinal cord compression) and SSE-free survival (SSE-FS) since LPD1. RESULTS: One-thousand nine hundred and twenty-three patients were included with a median follow-up from LPD1 of 16.7 months. Fifty-two percent (n = 996) started BHA prior or within 4 weeks after the start of LPD1 (early BHA). In total, 41% experienced at least one SSE. SSE incidence rate was 0.29 per patient year for patients without BHA and 0.27 for patients with early BHA. Median SSE-FS from LPD1 was 12.9 months. SSE-FS was longer in patients who started BHA early versus patients without BHA (13.2 vs. 11.0 months, P = .001). CONCLUSION: In a real-world population we observed an undertreatment with BHAs, although patients with early BHA use had lower incidence rates of SSEs and longer SSE-FS. This finding was irrespective of type of SSE and presence of risk factors. In addition to LPD treatment, timely initiation of BHAs is recommended in bone metastatic CRPC-patients with both pain and/or opioid use and prior SSE.

Real-world Outcomes of Sequential Androgen-receptor Targeting Therapies with or Without Interposed Life-prolonging Drugs in Metastatic Castration-resistant Prostate Cancer: Results from the Dutch Castration-resistant Prostate Cancer Registry.

BACKGROUND: Cross resistance between androgen-receptor targeting therapies (ARTs) (abiraterone acetate plus prednisone [ABI+P] or enzalutamide [ENZ]) for treatment of metastatic castration-resistant prostate cancer (mCRPC) may affect responses to second ART (ART2). OBJECTIVE: To establish treatment duration and prostate-specific antigen (PSA) response of ART2 in real-world mCRPC patients treated with or without other life-prolonging drugs (LPDs; ie, docetaxel, cabazitaxel, or radium-223) between ART1 and ART2. DESIGN, SETTING, AND PARTICIPANTS: Castration-resistant prostate cancer patients, diagnosed between 2010 and 2016 were retrospectively registered in Castration-resistant Prostate Cancer Registry (CAPRI). Patients treated with both ARTs were clustered into two subgroups: ART1>ART2 or ART1>LPD>ART2. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Outcomes were ≥50% PSA response and treatment duration of ART2. Descriptive statistics and binary logistic regression after multiple imputations were performed. RESULTS AND LIMITATIONS: A total of 273 patients were included with a median follow-up of 8.4 mo from ART2. Patients with ART1>ART2 were older and had favourable prognostic characteristics at ART2 baseline compared with patients with ART1>LPD>ART2. No differences between ART1>ART2 and ART1>LPD>ART2 were found in PSA response and treatment duration. Multivariate analysis suggested that PSA response of ART2 was less likely in patients with visceral metastases (odds ratio [OR] 0.143, p=0.04) and more likely in patients with a relatively longer duration of androgen-deprivation treatment (OR 1.028, p=0.01) and with ABI + P before ENZ (OR 3.192, p=0.02). A major limitation of this study was missing data, a common problem in retrospective observational research. CONCLUSIONS: The effect of ART2 seems to be low, with a low PSA response rate and a short treatment duration irrespective of interposed chemotherapy or radium-223, especially in patients with short time on castration, visceral disease, and ENZ before ABI+P. PATIENT SUMMARY: We observed no differences in outcomes of patients treated with sequential abiraterone acetate plus prednisone (ABI+P) and enzalutamide (ENZ) with or without interposed chemotherapy or radium-223. In general, outcomes were lower than those in randomised trials, questioning the additional effect of second treatment with ABI+P or ENZ in daily practice.

Second-Line Cabazitaxel Treatment in Castration-Resistant Prostate Cancer Clinical Trials Compared to Standard of Care in CAPRI: Observational Study in the Netherlands.

BACKGROUND: Cabazitaxel has been shown to improve overall survival (OS) in metastatic castration-resistant prostate cancer (mCRPC) patients after docetaxel in the TROPIC trial. However, trial populations may not reflect the real-world population. We compared patient characteristics and outcomes of cabazitaxel within and outside trials (standard of care, SOC). PATIENTS AND METHODS: mCRPC patients treated with cabazitaxel directly after docetaxel therapy before 2017 were retrospectively identified and followed to 2018. Patients were grouped on the basis of treatment within a trial or SOC. Outcomes included OS and prostate-specific antigen (PSA) response. RESULTS: From 3616 patients in the CAPRI registry, we identified 356 patients treated with cabazitaxel, with 173 patients treated in the second line. Trial patients had favorable prognostic factors: fewer symptoms, less visceral disease, lower lactate dehydrogenase, higher hemoglobin, more docetaxel cycles, and longer treatment-free interval since docetaxel therapy. PSA response (≥ 50% decline) was 28 versus 12%, respectively (P = .209). Median OS was 13.6 versus 9.6 months for trial and SOC subgroups, respectively (hazard ratio = 0.73, P = .067). After correction for prognostic factors, there was no difference in survival (hazard ratio = 1.00, P = .999). Longer duration of androgen deprivation therapy treatment, lower lactate dehydrogenase, and lower PSA were associated with longer OS; visceral disease had a trend for shorter OS. CONCLUSION: Patients treated with cabazitaxel in trials were fitter and showed outcomes comparable to registration trials. Conversely, those treated in daily practice showed features of more aggressive disease and worse outcome. This underlines the importance of adequate estimation of trial eligibility and health status of mCRPC patients in daily practice to ensure optimal outcomes.