The role of bone-targeted therapies for prostate cancer in 2017

Real-world incidence of symptomatic skeletal events and bone-modifying agent use in castration-resistant prostate cancer - an Australian multi-centre observational study

INTRODUCTION

Bone metastases occur frequently in castration-resistant prostate cancer (CRPC) and may lead to skeletal-related events (SREs), including symptomatic skeletal events (SSEs). Bone-modifying agents (BMAs) delay SREs and SSEs. However, the real-world use of BMAs is debated given the absence of demonstrated survival advantage and potential adverse events (AEs). Our retrospective study examined BMA use and SSE rates in Australian patients with CRPC.

METHODS

Patients with CRPC and bone metastases were identified from the electronic CRPC Australian Database. Patient characteristics, treatment patterns and AEs were analysed. Descriptive statistics reported baseline characteristics, SSE rates and BMA use. Comparisons between groups used t-tests and Chi-square analyses. Overall survival was calculated by the Kaplan-Meier method.

RESULTS

A total of 532 eligible patients were identified with a median age of 73 years (range: 44-97 years). BMAs were prescribed in 232 men (46%), 183 of whom received denosumab. Patients receiving first-line docetaxel for CRPC were more likely to commence BMAs than those receiving abiraterone or enzalutamide (51% vs 31% vs 38%; p = 0.004). SSEs occurred in 148 men (28%), most commonly symptomatic lesions requiring intervention (75%). At the time of initial SSEs, only 28% were receiving BMAs. Patients treated at sites with lower BMA use (<median) had higher SSE rates (32% vs 22%, p = 0.019).

CONCLUSION

In our real-world cohort, SSEs occurred in almost one-third of patients with CRPC and bone metastases, whereas less than half of patients received BMAs. The lower rate of SSEs in treatment sites with increased BMA use supports their benefit in this setting.

Treatment patterns of prostate cancer with bone metastasis in Beijing: A real-world study using data from an administrative claims database

PURPOSE

To explore treatment patterns among patients with prostate cancer and bone metastasis and to compare clinical outcomes following use of different hormone therapies including combined androgen blockade (CAB), nonsteroidal antiandrogen (NSAA) monotherapy, and castration monotherapy.

METHODS

We conducted a population-based cohort study using data from the Urban Employee Basic Medical Insurance database (2011-2014) in Beijing. We identified 475 patients with newly diagnosed bone metastatic prostate cancer with at least one prescription for hormone therapy and described their treatment patterns over a median follow-up of 20.7 months. Cox proportional hazards model was used to compare time to chemotherapy initiation between patients starting on different hormone therapies.

RESULTS

Hormone therapy and/or bisphosphonate therapy with zoledronic acid were the initial treatments in the majority of patients (87.8%); chemotherapy, radiotherapy, and surgery were usually given later in the treatment pathway. CAB was the most common hormone treatment (73.7%). For time to chemotherapy initiation, hazard ratios (95% confidence intervals) were 2.43 (1.08-5.44) for NSAA alone vs CAB and 1.29 (0.78-2.13) for castration alone vs CAB.

CONCLUSIONS

Our findings show that while a wide range of therapies are used to treat patients with prostate cancer and bone metastasis in Beijing, hormone therapy and bisphosphonate therapy are the most commonly prescribed, and use of CAB was seen to be advantageous in delaying time to chemotherapy initiation over NSAA monotherapy. Future studies should explore longer-term treatment patterns, including use of newly approved treatments.

Bone-targeted therapy in castration-resistant prostate cancer: where do we stand?

INTRODUCTION

In the last years, there have been significant developments in the therapeutic armamentarium of metastatic castration-resistant prostate cancer (mCRPC). New evidence shows that the addition of bone-targeted agents (BTA) to "life-prolonging agents" result in improved clinical benefit. This review aims to give an overview of data for the use of BTAs in a new era of mCRPC where new agents are used in daily practice.

EVIDENCE ACQUISITION

A non-systematic review of the literature was performed combining the keywords: "castration-resistant prostate cancer" and "bone-targeted therapy". The primary objective was to provide a critical assessment of data for the use of BTAs in mCRPC, and the secondary objective was to assess novel targeted therapy.

EVIDENCE SYNTHESIS

Zoledronic acid and denosumab have shown to be effective in reducing the risk of SREs in patients with mCRPC. The point at which treatment with bisphosphonates or denosumab should be initiated during PCa evolution has yet to be determined. The EMA has restricted the usage of Ra-223 to patients who have had two previous treatments for mCRPC to the bone or who cannot receive other treatments. Ra-223 should only be used as monotherapy or in combination with ADT for the treatment of mCRPC, symptomatic bone metastases and without visceral metastases. With recent developments in PSMA-targeted radiopharmaceuticals, PSMA RLT agents are now under investigation for the treatment of mCRPC.

CONCLUSIONS

Reducing skeletal-related morbidity remains a crucial goal of palliative life-extending therapy in mCRPC. New data about dosing schedules and combinations of different treatments will continue to refine the optimal strategy for incorporating BTAs into the new treatment paradigms for PCa. Novel molecules such as PSMA-targeted small molecules promise theranostic agents in the management of PCa patients.