Treatment of metastatic castration resistant prostate cancer with radium-223: a retrospective study at a US tertiary oncology center.

BACKGROUND: Guidelines for optimal sequencing of radium-223 and chemotherapy for metastatic castration resistant prostate cancer (mCRPC) do not exist. This study evaluated treatment patterns and overall survival (OS) among patients with mCRPC treated with radium-223 in an academic clinical setting. METHODS: A retrospective study was conducted of bone metastases-predominant mCRPC patients treated with radium-223. Treatment patterns from 2013 to 2018 were evaluated in patients treated with radium-223 pre- vs. post-chemotherapy. OS was examined using Kaplan-Meier medians and 95% confidence intervals. RESULTS: In total, 220 patients were treated with radium-223 (64 pre-chemotherapy, 83 post-chemotherapy, 73 no chemotherapy). Mean radium-223 injections per patient was 5.3 and 4.3 in the pre- vs. post-chemotherapy cohorts, respectively (p < 0.001). The number of chemotherapy cycles was similar for chemotherapy given pre- or post-radium-223. Mean line of mCRPC therapy of radium-223 was 3rd and 5th when given pre- and post-chemotherapy, respectively (p < 0.001). 41.8% patients were treated with radium-223 in combination with another mCRPC therapy, commonly abiraterone acetate (43.5%) or enzalutamide (52.2%). The majority received combination therapy for the duration of radium-223 treatment; 20.7% started another agent after radium-223 initiation; 20.7% initiated radium-223 while on established therapy. Median OS from first mCRPC treatment was 39.4 months (95% CI 33.0, 48.8) for patients with radium-223 pre-chemotherapy vs. 37.4 months (95% CI 32.0, 43.5) post-chemotherapy (and 35.2 months [95% CI 27.9, 43.3] vs. 32.0 months [95% CI 26.9, 36.0] for patients with radium-223 combination vs. monotherapy). CONCLUSIONS: This retrospective analysis of patients treated with radium-223 demonstrates that administration of radium-223 pre-chemotherapy increased likelihood of completion of radium-223 treatment. Radium-223 given pre- or post-chemotherapy and with or without combination therapy did not result in significant differences in OS. Additional studies are needed to determine the optimal sequencing strategy of mCRPC in the modern era.

Patient and caregiver benefit-risk preferences for nonmetastatic castration-resistant prostate cancer treatment.

BACKGROUND: Recently approved second-generation androgen receptor inhibitors (SGARIs) for non-metastatic castration-resistant prostate cancer (nmCRPC) have similar efficacy but differ in safety profiles. We used a discrete choice experiment (DCE) to examine how nmCRPC patients and caregivers perceive the benefits versus risks of these new treatments. METHODS: An online DCE survey with 14 treatment choice questions was administered to nmCRPC patients and caregivers. Each choice question compared two hypothetical medication profiles varying in terms of 5 safety attributes (risk or severity of adverse events [AEs]: fatigue, skin rash, cognitive problems, serious fall, and serious fracture) and two efficacy attributes (duration of overall survival [OS] and time to pain progression). Random parameters logit models were used to estimate each attribute's relative importance. We also estimated the amounts of OS that respondents were willing to forego for a reduction in AEs. RESULTS: In total, 143 nmCRPC patients and 149 caregivers viewed the AEs in following order of importance (most to least): serious fracture, serious fall, cognitive problems, fatigue, and skin rash. On average, patients were willing to trade 5.8 and 4.0 months of OS to reduce the risk of serious fracture and fall, respectively, from 3% to 0%; caregivers were willing to trade 6.6 and 5.4 months of OS. CONCLUSIONS: nmCRPC patients and caregivers preferred treatments with lower AE burdens and were willing to forego OS to reduce the risk and severity of AEs. Our results highlight the importance of carefully balancing risks and benefits when selecting treatments in this relatively asymptomatic population.

Physician preferences for non-metastatic castration-resistant prostate cancer treatment.

BACKGROUND: Recent approvals of second-generation androgen receptor inhibitors (SGARIs) have changed the treatment landscape for non-metastatic castration-resistant prostate cancer (nmCRPC). These SGARIs have similar efficacy but differ in safety profiles. We used a discrete choice experiment to explore how United States physicians make treatment decisions between adverse events (AEs) and survival gains in nmCRPC, a largely asymptomatic disease. METHODS: Treating physicians (n = 149) participated in an online survey that included 14 treatment choice questions, each comparing 2 hypothetical treatment profiles, which varied in terms of 5 safety and 2 efficacy attributes. We described safety attributes (fatigue, skin rash, cognitive problems, falls, and fractures) in terms of severity and frequency, and efficacy attributes (overall survival [OS] and time to pain progression) in terms of duration of effect. We used a random parameters logit model to estimate preference weights and importance scores for each attribute. We also estimated the amount of survival gain physicians were willing to trade for a reduction in specific AEs between treatment options. RESULTS: Physicians placed more importance on survival than on time to pain progression, and viewed a reduction in cognitive problems from severe to none, a reduction in risk of a serious fracture from 8% to none, and a reduction in fatigue from severe to none as the most important safety attributes. Physicians were willing to forego 9.1 and 6.6 months of OS, respectively, to reduce cognitive problems and fatigue from severe to mild-to-moderate. To reduce the risk of a serious fracture from 8 to 5% and 5% to none, physicians were willing to trade 3.9 and 5.3 months of OS, respectively. CONCLUSIONS: Physicians were willing to trade substantial amounts of survival to avoid AEs between hypothetical treatments. These results emphasize the importance of carefully balancing therapies' benefits and risks to ultimately optimize the overall quality of nmCRPC patients' survival. Nonetheless, it is noted that the results from the study sample of 149 physicans may not be representative of the viewpoints of all nmCRPC-treating physicians.