Impact of timing of administration of bone supportive therapy on pain palliation from radium-223.

Abstract

5023 Background: Skeletal-related events (SREs) drive morbidity in patients with metastatic castration-resistant prostate cancer (mCRPC). In the ALSYMPCA study, Radium-223 (Ra223) was found to palliate pain in addition to prolonging survival and reducing SREs. Earlier onset of pain relief was noted when zoledronic acid (ZA) was administered within 24-48 hours of samarium; we evaluated whether the timing of bone supportive therapy (BST) affected pain palliation fromRa223. Methods: We identified patients who received Ra223 at University of Southern California or Mayo Clinic Arizona. Data extracted: Ra223 administration dates, pain scores, pain medications, ZA or denosumab administration dates, alkaline phosphatase (ALP) levels, prostate specific antigen (PSA) levels, and concurrent prostate cancer therapy. Patients were evaluable for pain response if they had at least 2 pain scores documented before and after Ra223 with pain medication use data. Pain response was defined as > 2 point decrease in pain on a 10 point scale; flare was defined as > 2 point increase followed by return to baseline or lower. Results: Of 65 patients, 20 had baseline pain score > 0 and 34 were evaluable. Median #doses Ra223 was 5 (range 2-6). 18 patients received concurrent abiraterone (abi) or enzalutamide (enza), 16 did not. Pain response occurred in 6/6 (100%) patients who received BST within 1 month prior to first Ra223 dose and 4/8 (50%) patients who did not receive BST. Pain flare occurred in 6/21 patients (29%) without BST and 2/13 (15%) with BST. 6/10 (60%) patients with pain response had ALP decline but there was no consistent pattern of ALP changes in patients with flare. 8/8 patients with pain response had no PSA decline (6 increased, 2 stable). 6/12 (50%) and 2/22 (9%) patients on abi/enza had pain response and flare respectively, and 4/8 (50%) and 6/19 (32%) patients without concurrent abi/enza had response/flare. Conclusions: BST within 1 month prior to first Ra223 may be associated with increased likelihood of pain palliation and may prevent pain flare. PSA/ALP changes do not predict pain response. Concurrent use of abi/enza does not increase the likelihood of pain response and may decrease the likelihood of flare.