Improvements in symptoms related to bone metastasis in recipients of Lutetium-177 PSMA-617 for prostate cancer.

Abstract

96 Background: Prostate-specific membrane antigen (PSMA) radioligand therapy (RLT) targeted to prostate-specific membrane antigen (PSMA) is a new targeted treatment for progressive metastatic castration-resistant prostate cancer (mCRPC). PSMA-RLT conjugates a radionuclide to a small molecule ligand with affinity for PSMA. Recent trials, such as TheraP and VISION, established improvements in progression free survival, overall survival, and patient-reported outcomes (PROs) for PSMA-RLT. Less is known about the impact of PSMA-RLT on symptoms related to bone metastasis (BM), commonly causing significant morbidity in men with mCRPC. The optimal tools for PRO collection with PSMA-RLT are also uncertain. We previously reported improvements in Brief Pain Inventory and now report EORTC QLQ-BM22 data to describe change in symptoms related to bone metastasis among men receiving PSMA-RLT for mCRPC. Methods: From 2015 to 2017, 50 patients received up to 4 cycles of 177Lu-PSMA-617 every 6 weeks (trial registration: ACTRN12615000912583). Patients completed a validated assessment of bone metastasis-related pain (EORTC QLQ-BM22) prior to each cycle and 6 or 12 weeks after the last cycle of 177Lu-PSMA. Change in pain over the course of the study was examined using linear mixed effects models. We also examined whether unadjusted changes in PROs exceeded published cutoffs for minimal clinically important difference scores. Results: Patients reported reduced bone metastasis-related pain at various sites over time ( p =.01). Of 44 patients completing this scale before cycle 2, 22 (50%) reported clinically significant improvement in pain at various sites. At follow-up, of the 37 patients alive, 25 provided evaluable data on bone metastasis-related pain. Of these, 10 (40%) reported clinically significant improvement in pain at various sites. Patients also reported less functional interference from pain over time ( p <.01) and lower consistency, intermittency, and difficulty alleviating pain with medication over time ( p =.01). Before cycle 2 and at follow-up, 26% and 38% of respondents reported clinically significant reduction in functional interference from pain. Before cycle 2 and at follow-up, 33% and 42% of respondents reported clinically significant improvement in consistency, intermittency, and difficulty alleviating pain with medication. Conclusions: 177Lu-PSMA RLT resulted in improvements in bone metastasis-related symptoms, supporting prior findings using other PRO measures. At follow-up, 38-42% of patients completing PRO assessment reported clinically meaningful improvements in bone metastasis-related pain, a significant contributor to quality of life. Clinical trial information: ACTRN12615000912583.