Radium-223 in metastatic castration resistant prostate cancer: Progression free survival and pain scores—Real-world single-institution experience.

Abstract

250 Background: Radium-223 (Ra223) is a novel alpha-emitting radiopharmaceutical agent approved for use in patients with metastatic castration resistant prostate cancer (mCRPC) and bone metastases based on ALSYMPCA results. We report our early experience in this setting. Methods: 36 patients were treated with Ra223 from Feb 2014 - Aug 2015. The patients were planned to receive 6 injections at a dose of 50 kBq/kg every 4 weekly. The pain was assessed using the visual analogue score (VAS). The effect of 6 cycles of Ra223 on blood counts, serum alkaline phosphatase (SAP), PSA, VAS and progression free survival (PFS) were evaluated. Results: At baseline (BL) median age was 79years; 66% of patients were ECOG 0-1; median VAS was 6. 53% had received prior docetaxel. 18 patients (50%) received all the scheduled 6 cycles of Ra223. In these patients there was a significant reduction in the pain scores both after the first cycle and after 6 cycles compared to the BL score (p < 0.05 & p < 0.001, respectively). A 30% reduction in the SAP levels was seen (p = 0.03). The reduction in pain scores was independent of the PSA response. The treatment was well tolerated with no grade 3,4 toxicity. Discontinuation rate was 50% (18/36) and was due to disease progression. Prior docetaxel use was associated with a higher discontinuation rate (12/18), as was albumin level < 34g/dL (60% vs. 43%). 7 (19%) required blood transfusions during the course. The median PFS was 6.1 months. It was significantly longer in those who completed 6 cycles of treatment and in patients with SAP < 220 U/L (10.97vs.5.2 & 10.33vs.6.4 months, respectively: p < 0.0001). There was a non-significant trend towards longer PFS in patients who had no prior docetaxel (10.33vs.6.5m; p = 0.05) and in patients with Albumin > 34 (8.9vs.6.4m; p = 0.06). Conclusions: Ra223 is a safe and effective treatment for mCRPC with bone metastases. Completion of 6 cycles is associated with a significantly better PFS, reduction in pain scores and in SAP levels. Prior docetaxel use and lower albumin levels were associated with a higher discontinuation rate and this should be considered in the decision process for optimising therapy sequencing.