Administering bone supportive therapy within 1 month prior to starting radium Ra 223 dichloride (Xofigo) may increase the likelihood of achieving pain palliation with the radionuclide therapy and reduce the chance of pain flare, according to the findings of a retrospective study.
Administering bone supportive therapy (BST) within 1 month prior to starting radium Ra 223 dichloride (Xofigo) may increase the likelihood of achieving pain palliation with the radionuclide therapy and reduce the chance of pain flare, according to the findings of a retrospective study presented at the American Society of Clinical Oncology annual meeting in Chicago.
The research, conducted by investigators from the University of Southern California, Los Angeles, and Mayo Clinic, Phoenix, AZ, identified 65 men treated with Ra 223, of whom 22 (34%) received BST with either denosumab (Xgeva) or zoledronic acid (Zometa) within 1 month prior to Ra 223. Pain palliation and flare after starting Ra 223 were analyzed using pain severity data scored on a 0 to 10 scale.
Fourteen men (six on BST and eight not on BST) were evaluable for pain palliation based on having a pain score >0 prior to starting Ra 223 and data from at least one subsequent pain score with information on pain medication use. Pain response (palliation), defined as a ≥2 point decrease after starting Ra 223 without increased pain medication use, was achieved by all six men who started BST within 1 month prior to Ra 223. Among the eight men who were not on BST, only four (50%) achieved pain palliation, and three (37.5%) experienced pain progression defined as worsening of the pain score.
The analysis of pain flare included 34 men who had pain score data available prior to starting Ra 223 and from at least two subsequent visits. Flare, defined as a ≥2 point increase followed by a return to baseline or lower, occurred in two (15%) of 13 patients on BST and in six (29%) of 21 patients not on BST.
“We were interested in investigating the impact of the timing of BST administration on pain palliation in men receiving Ra 223 because a previously published study showed that administering zoledronic acid 48 to 72 hours prior to samarium-153 resulted in faster and better pain relief. In addition, we wanted to investigate if BST had potential benefit for mitigating pain flare that can occur in up to 30% of patients starting on Ra 223,” said Kelly Yap, MD, of the University of Southern California.
“Our study is retrospective, includes a relatively small number of patients, and the differences between groups did not achieve statistical significance. However, we believe the findings support the administration of BST up to 1 month before initiating treatment with Ra 223, assuming there are no contraindications to BST," said Dr. Yap.
The investigators also analyzed their data for patterns in pain response and flare related to concurrent treatment for prostate cancer with androgen receptor signaling inhibitors. The findings indicated that use of those medications did not increase the likelihood of pain palliation, but might decrease the likelihood of flare.
Of the 14 men evaluable for pain response, eight were on abiraterone (ZYTIGA) or enzalutamide (XTANDI). Pain response was documented for six (75%) of those eight men compared with four (67%) of the six men not on concurrent treatment with an androgen receptor signaling inhibitor.
Of the 34 men evaluable for pain flare, 18 were on abiraterone or enzalutamide, and only two (11%) of those men experienced a pain flare after starting Ra 223 compared with six (38%) of the 16 men not on concurrent treatment (p=.12).
“Our study does not allow us to make any recommendations on the use of concurrent abiraterone or enzalutamide in men getting Ra 223. Based on our results, however, it seems that if men are already on these treatments, it is probably beneficial to continue them,” said Dr. Yap.
PSA and alkaline phosphatase levels were also analyzed, but changes in those laboratory tests were not found to be predictive of pain response in men starting on Ra 223.
Two of Dr. Yap’s co-authors have a financial or other relationship with several pharmaceutical companies, one of these co-author’s institution has received research funding from pharmaceutical companies.
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