Implementation and preliminary validity of the Functional Assessment of Cancer Therapy – Radionuclide Therapy (FACT-RNT) in patients receiving radionuclide therapy for prostate cancer.

118 Background: The Functional Assessment of Cancer Therapy-Radionuclide Therapy (FACT-RNT) is used in trials and clinical practice to monitor patient-reported RNT-relevant symptoms and toxicities in advanced metastatic castrate-resistant prostate cancer (mCRPC) patients receiving RNT. This study examined FACT-RNT feasibility and preliminary validity for U.S. patients receiving RNT. Methods: Patients scheduled to start 177Lu-PSMA-617 for advanced mCRPC at Moffitt Cancer Center from October 2023 – March 2024 completed patient-reported outcome (PRO) measures before each cycle. PROs included previously validated measures of prostate cancer specific-symptoms (NFPSI-17) and physical function (Scored Patient-Generated Subjective Global Assessment; PG-SGA) and the FACT-RNT, a 15-item measure of symptoms/toxicities with higher total scores (range: 0-60) indicating less symptom burden. Correlations between the FACT-RNT and other PROs were calculated. Results: Patients (N=17) were, on average, 69 years old (SD=11, range=43-90) at RNT cycle 1 and mostly non-Hispanic (76%) and White (82%). Gleason scores at diagnosis were 7-8 (30%) or 9-10 (71%). Patients had previously undergone surgery (35%), chemotherapy (94%), radiation (71%), hormone therapy (94%), targeted therapy (88%), and immunotherapy (29%). Fifteen patients (88%) received ≥2 RNT infusions; of these, 1 (6%) died and 1 (6%) discontinued RNT prior to cycle 2. Thirteen (87% of those with ≥2 infusions) completed the FACT-RNT at ≥2 cycles. Cycle 1 FACT-RNT total scores ranged from 31-58 (M=46.5, SD=8). The FACT-RNT was positively associated with symptoms as assessed by NFPSI-17 at cycles 1-3 ( p s≤.03) and negatively associated with physical function at cycles 1-2 ( p s≤.05). Conclusions: Preliminary results support FACT-RNT validity due to associations with validated PRO measures and the feasibility of FACT-RNT implementation in the U.S. The FACT-RNT may be helpful in clinical management and decision-making with RNT recipients. Future research will replicate and extend these findings in a larger longitudinal sample and examine validity with clinician-rated outcomes and RNT dosimetry.