Hematotoxicity and non-hematological adverse events of Ra-223 dichloride (Ra-223) in patients with castration-resistant prostate cancer (CRPC) and bone metastases.

1227 Objectives Ra-223 is a first-in-class alpha-emitting pharmaceutical recently Food and Drug Administration approved for treatment of CRPC patients with bone metastases. The aim of this study was to investigate the incidence and severity of hematotoxicity and other non-hematological adverse events (AE) of this therapy. . Methods Eligible patients had progressive hormone and/or chemo refractory PC with bone metastases and no known visceral involvement. Bone scintigraphy was performed in all patients 1-2 weeks prior to Ra-223 Therapy. All patients received CBC and renal tests as well as measurements of PSA and alkaline phosphatase (ALP) on the therapy days and at least 4 weeks after the last therapy. Results a total of 119 treatments (range: 1-6 (median: 4)) were performed for 29 patients (mean age: 74 (range: 56-86)) between March and December 2014 with a mean PSA-Value of 579 ng/ml (0.5-4710) and a mean ALP of 203 U/l (43-517). 17/29 patients had a history of chemotherapy. Relevant hematotoxicity (grade 3) occurred in just 1 patient (3%) with initial cytopenia, otherwise max a grade 1 hematotoxicity has been observed. There was not any significant correlation between the cumulative activity and the level of hematotoxicity. 67 treatments were not associated with any subjective side effects. The most important non-hematological AE were mild diarrhea for 2-3 days in about 7-10 days after 13 therapies and severe generalized pain in 2 patients began 3 h after application, which lasted 1 day. No renal toxicity was observed. Conclusions Ra-223 is a well-tolerated therapy for CRPC with bone metastases.