Association between SPECT/CT total tumor volume (TTV) and new lesions (NLs) in early cycles of 177Lu-PSMA-617 (LuPSMA) and progression-free and overall survival (PFS and OS) in men with metastatic castration-resistant prostate cancer (mCRPC).

• DOI: 10.1200/jco.2024.42.4_suppl.40
• Publication Date: 2024-01-29T21:06:41Z
• Authors: Ridvan Arda Demirci; Roman Gulati; Peter Nelson; Heather H. Cheng; Jessica E. Hawley; Todd Yezefski; Michael C. Haffner; Robert Bruce Mont...; Michael Thomas Sc...; Evan Y. Yu; Delphine L Chen; Amir Iravani
• Keywords: Progression-free survival

40 Background: LuPSMA is a newly established treatment in patients with mCRPC, but PSA and survival outcomes vary widely, predictors of responses are needed. delivers radiation to tumor tissues that can also be imaged SPECT/CT which provides semiquantitative estimates TTV identification NLs. This study investigates the use early cycles predict outcomes. Methods: Between June December 2022, mCRPC who initiated 2 nd cycle 24 hours post-treatment were retrospectively reviewed. We evaluated associations between appearance NLs at start or 3 rd PFS OS using Cox regression analysis. classified as non-PSMA-avid no low uptake (< liver) corresponding findings on CT PSMA-avid (uptake > liver). All analyses adjusted for change relative baseline. Results: Sixty-six (median age, 73.5) received median 4 (IQR: 3-5) LuPSMA. Median follow-up starting was 26 weeks 21-36) 47/66 (71%) alive time A reduction ≥50% (PSA50) noted 33/66 (50%) patients. Changes apparently concordant 50/66 (76%) 42/51 (82%) significantly correlated (r= 0.55 0.56, both p<0.001). Patients higher absolute had worse (HR=1.3 2.26) consistent results (Table). detected 13/66 (7/13 PSMA-avid, 6/13 non-PSMA-avid) 7/51 (5/7 2/7 cycle, respectively. risks progression death (HR=4.53 6.28). Conclusions: Higher detection associated death. Although changes correlated, provided complementary ability [Table: see text]