RT Journal Article SR Electronic T1 Prospective, Single-Arm Trial Evaluating Changes in Uptake Patterns on Prostate-Specific Membrane Antigen (PSMA)-Targeted 18F-DCFPyL PET/CT in Patients with Castration-Resistant Prostate Cancer Starting Abiraterone or Enzalutamide JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP jnumed.120.259069 DO 10.2967/jnumed.120.259069 A1 Katherine A. Zukotynski A1 Urban Emmenegger A1 Sebastien Hotte A1 Anil Kapoor A1 Wei Fu A1 Amanda L. Blackford A1 John Valliant A1 Francois Benard A1 Chun K. Kim A1 Mark C. Markowski A1 Mario A. Eisenberger A1 Emmanuel S. Antonarakis A1 Kenneth J. Pienta A1 Michael A. Gorin A1 Matthew Lubanovic A1 Jihyun Kim A1 Martin G. Pomper A1 Steve Y. Cho A1 Steven P. Rowe YR 2021 UL http://jnm.snmjournals.org/content/early/2021/02/19/jnumed.120.259069.abstract AB Purpose: Positron emission tomography (PET) with small molecules targeting prostate-specific membrane antigen (PSMA) is being adopted as a clinical standard for prostate cancer (PCa) imaging. In this study, we evaluated changes in uptake on PSMA-targeted PET in men starting abiraterone or enzalutamide. Methods: This prospective, single-arm, two-center, exploratory clinical trial enrolled men with metastatic castration-resistant prostate cancer (CRPC) initiating abiraterone or enzalutamide. Each patient was imaged with 18F-DCFPyL at baseline and within 2-4 months after starting therapy. Patients were followed for up to 48 months from enrollment. A central review evaluated baseline and follow-up PET scans recording change in maximum standardized uptake value (SUVmax) at all disease sites and classifying the pattern of change. Two parameters: the delta percent SUVmax (DPSM) of all lesions and the delta absolute SUVmax (DASM) of all lesions were derived. Kaplan-Meier curves were used to estimate time to therapy change (TTTC) and overall survival (OS). Results: Sixteen evaluable patients were accrued to the study. Median TTTC was 9.6 months (95% confidence interval (CI), 6.9-14.2) and median OS was 28.6 months (95% CI 18.3-not available (N/A)). Patients with a mixed-but-predominantly-increased pattern of radiotracer uptake had shorter TTTC and OS. Men with low DPSM had median TTTC 12.2 months (95% CI 11.3-N/A) and median OS 37.2 months (95% CI 28.9-N/A), while those with high DPSM had median TTTC 6.5 months (95% CI 4.6-N/A, P = 0.0001) and median OS 17.8 months (95% CI 13.9-N/A, P = 0.02). Men with low DASM had median TTTC 12.2 months (95% CI 11.3-N/A) and median OS N/A (95% CI 37.2 months-N/A), while those with high DASM had median TTTC 6.9 months (95% CI 6.1-N/A, P = 0.003) and median OS 17.8 months (95% CI 13.9-N/A, P = 0.002). Conclusion: Findings on PSMA-targeted PET 2-4 months after initiation of abiraterone or enzalutamide are associated with TTTC and OS. Development of new lesions and/or increasing intensity of radiotracer uptake at sites of baseline disease are poor prognostic findings suggesting shorter TTTC and OS.