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Abiraterone acetate combined with Prednisone/Prednisolone (AA+P) and Enzalutamide (ENZ) have proven survival benefit in men with metastatic castration-resistant prostate cancer (mCRPC) in chemotherapy-naïve and prior chemotherapy patients. There have been no studies directly comparing the effectiveness of ENZ to AA+P in mCRPC patients.A retrospective, survival analysis study of 143 real-world mCRPC patients (90 in AA+P and 53 in ENZ group) was conducted. Patients who started their treatment between February 2012 and May 2016 were included. The primary end point was biochemical progression-free survival (bPFS). Secondary end points were radiological progression-free survival (rPFS) and overall survival (OS). Toxicity data were also collected. Data were analyzed using Cox proportional hazards (PH) models, adjusting for covariates: prior radical treatment; Gleason score; prostate-specific antigen; age; and chemotherapy naïve or not.After median follow-up of 15 months (interquartile range 7 to 23), 112 events of biochemical progression were observed (71 in AA+P and 41 in ENZ). About 41% in AA+P group and 30% patients in ENZ group received prior chemotherapy. The chance of biochemical progression was significantly lower among ENZ patients than AA+P patients, when adjusting for all covariates in the Cox PH model (hazard ratio [HR] 0.54, 95% confidence interval [CI] 0.35 to 0.82,This study showed a statistically significant difference in bPFS, favoring ENZ, but no significant difference in rPFS or OS.

e17034 Background: Studies have shown an improvement in overall survival (OS) and symptom control in metastatic castration-resistant prostate cancer (mCRPC) with Radium-223 treatment. However, there is little information about predicting outcomes using either PSA or Alkaline Phosphatase (ALP) response or comparing bone only disease to bone and lymph node (LN) involvement. Methods: 335 patients receiving Radium 223 at 6 UK centres between March 2014 and June 2020 were included. The primary endpoint was overall survival, secondary endpoints were toxicity, symptomatic benefit and skeletal-related events(SRE) Results: The median age was 75, with 71% having bone only metastases and 29% also having lymph node involvement. Those with PSA response (30%) had a statistically significant improvement in OS, compared to non-responders (18.2 vs 13.8 months, p = 0.026). They also showed highest rate of imaging response/stable disease (54% vs 34%). ALP response was seen in 82%. This did not translate to significantly improved OS, but did correlate with better symptomatic benefit (40% vs 29%). Those with bone only disease showed a survival benefit compared to those with LN involvement (19.4 vs 11.4 months, p = 0.046). Other than anaemia (23.5%), Grade 2 or above toxicities were uncommon including thrombocytopenia and neutropenia(5.5 and 6.2% respectively ) . 14% patients required at-least one blood transfusion. SRE were seen in 24% overall, but lower of in PSA responders(18%). Conclusions: Real life multicentre data suggests that PSA response and bone only disease could be predictors for better survival following Radium-223, whereas ALP response correlates better with symptomatic benefit.

e19190 Background: Upfront docetaxel is now standard of care for men with newly diagnosed metastatic hormone naïve prostate cancer .After disease progression following upfront docetaxel, various treatment agents including further lines of chemo or novel hormonal agents are used but there have been no convincing evidence or consensus opinion about optimal sequencing. Methods: We have conducted a national study in the UK by approaching oncologists who treat prostate cancer with systemic therapies. The oncologists were requested to complete a web based survey about their treatment decisions . Aim were to gain an insight about current practice following docetaxel in the UK and to identify the various disease and patients related factors which could influence the decision-making process. Results: 114 oncologists were invited and 59 have responded, 80% clinical oncologist and 20% medical oncologists respectively. At the point of castrate-resistant disease progression, following docetaxel, abiraterone was most commonly used agents (63%), followed by Enzalutamide (29%), cabazitaxel (6%) and docetaxel re-challenge respectively. Time difference between finishing docetaxel and disease progression was considered the most important deciding factor to choose next agents. Other important factors as per responders were volume of the disease, patients current symptoms, co morbidities and site of metastases . Most oncologists felt initial PSA and Gleason scores were two least important deciding factors. Patients with low volume disease, 92 % oncologist preferred abiraterone or enzalutamide as opposed to chemotherapy. When disease progressed within 6 months of completion of docetaxel, only one fifth of responder would use further chemo in next line .After novel hormone agents, cabazitaxel was the most commonly prescribed agents. 81% of clinicians would consider re-challenging with Docetaxel at some point of treatment sequencing; of these the majority would only consider this after a minimal interval of 12-18 months following upfront treatment. Conclusions: Our study has demonstrated a wide variation of practice in the UK. It has reflected that the decision is complex and there is clear need for further evidence or guideline for sequencing.

667 Background: Sunitinib and pazopanib are are effective treatment options for metastatic Renal cell carcinoma (mRCC) and both may impair patient’s quality of life (QOL). There has been no direct comparison between these agents and their effect on these domains. Methods: A prospective study of mRCC patients who had received Sunitinib or Pazopanib as a first line treatment was conducted. A set of questionnaires has been developed in-house, influenced by existing recognised tools, such as EORTC-C 30 and PHQ-9, and is tailored to focus on relevant QoL issues patients face. This questionnaire named as Patient reported outcome tool. They primarily relate to physical, emotional and social functioning in the quality of life of patients. Each category has 4 questions. The questions are quite generic and allow patients to apply them to what’s important in their lives. Answers are on a scale of 0-10. The purpose of the questionnaire is to assess a balance of physical, cognitive and independence related aspects of their life over the course of their treatment. All patients are asked to complete the baseline questionnaire and then in every clinical visit. Results: Data were collected prospectively of metastatic RCC patients who had received Sunitinib or Pazopanib from May 2017 to Aug 2018. Total 45 patients were included, 23 received Pazopanib and 22 were on Sunitinib. There was a higher rate of significant worsening for the physical well-being subscale for Sunitinib versus Pazopanib. Patients on Sunitinib reported worsening tiredness, skin problems and sleep disturbance. Socially, patients on Sunitinib reported more closer to family, better interaction with friends and more motivated to go out. Problem with feeling sad, fear of death and anxiousness were more pronounced on Pazopanib arm. Conclusions: Our study suggested that there are marked differences between Sunitinib vs Pazopanib and their effects on patients physical, emotional and social wellbeing. Physical function was more influenced by sunitnib while pazopanib has more effect emotional wellbeing. Further studies are warranted to confirm these findings.

303 Background: Abiraterone acetate (a prodrug of abiraterone, which is a selective inhibitor of androgen biosynthesis) combined with prednisone/prednisolone (AA+P) and enzalutamide (ENZ) (an androgen-receptor–signalling inhibitor) have proven survival benefit in men with metastatic castration resistant prostate cancer (mCRPC) in chemo naïve and prior chemo patients. There have been no studies directly comparing the effectiveness of ENZ to AA+P in mCRPC patients. Methods: A retrospective, survival analysis study of 143 real world mCRPC patients (90 in AA+P and 53 in ENZ group) was conducted. Patients who started their treatment between 1st February 2012 and 31st May 2016 were included. The primary endpoint was biochemical progression free survival (PFS). Secondary end points were radiographic progression free survival (rPFS) and overall survival (OS). Data was analysed using Cox proportional hazards models, adjusting for covariates: prior radical or palliative treatment; Gleason score; baseline PSA; age; and chemo naïve or not. Results: After median follow up of 15 months (IQR 7 to 23) 112 events of biochemical progression were observed (71 in AA+P and 41 in ENZ). 41%in AA+P group and 30% patients in ENZ group received prior chemo. The chance of biochemical progression was significantly lower among ENZ patients than AA+P patients, when adjusting for all covariates in the Cox PH model (Hazard Ratio 0.54, 95% CI 0.35 to 0.82, p=0.004. There was a trend implying the chance of rPFS could be higher among ENZ patients than AA+P patients (HR 1.24, 95% CI 0.76 to 2.02, p=0.4). OS is lower among ENZ patients than AA+P patients, when adjusting for all covariates in the Cox PH model (HR 0.91, 95% CI 0.59 to 1.41, p=0.7). 38% of ENZ patients reported fatigue compared to 16% of AA+P patients while hypertension was reported slightly more in AA+P patients than in ENZ patients. Conclusions: This study showed a statistically significant difference in biochemical progression-free survival, favouring ENZ, but no significant difference in radiographic progression-free survival or overall survival.

e18857Background: Enzalutamide (ENZ) and abiraterone acetate plus prednisone (AA+P) are effective treatment options for metastatic castration-resistant prostate cancer (mCRPC) and both may impair p...

e16101 Background: Treatment with Abiraterone acetate (AA) combined with prednisolone has proven benefit in overall survival compared with prednisolone alone in men with metastatic castration resis...