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Updated: Nov 16, 2025
A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer
Published on: March 6, 2018
Prospective, Single-Arm Trial Evaluating Changes in Uptake Patterns on Prostate-Specific Membrane Antigen-Targeted
Katherine A Zukotynski, Urban Emmenegger1, Sebastien Hotte2
1Sunnybrook Odette Cancer Centre and Research Institute, University of Toronto, Toronto, Ontario, Canada.
Abstract:
PET with small molecules targeting prostate-specific membrane antigen (PSMA) is being adopted as a clinical standard for prostate cancer imaging. In this study, we evaluated changes in uptake on PSMA-targeted PET in men starting abiraterone or enzalutamide. Methods: This prospective, single-arm, 2-center, exploratory clinical trial enrolled men with metastatic castration-resistant prostate cancer initiating abiraterone or enzalutamide. Each patient was imaged with 18F-DCFPyL at baseline and within 2-4 mo after starting therapy. Patients were followed for up to 48 mo from enrollment. A central review evaluated baseline and follow-up PET scans, recording change in SUVmax at all disease sites and classifying the pattern of change. Two parameters were derived: the δ-percent SUVmax (DPSM) of all lesions and the δ-absolute SUVmax (DASM) of all lesions. 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 mo (95% CI, 6.9-14.2), and median OS was 28.6 mo (95% CI, 18.3-not available [NA]). Patients with a mixed-but-predominantly-increased pattern of radiotracer uptake had a shorter TTTC and OS. Men with a low DPSM had a median TTTC of 12.2 mo (95% CI, 11.3-NA) and a median OS of 37.2 mo (95% CI, 28.9-NA), whereas those with a high DPSM had a median TTTC of 6.5 mo (95% CI, 4.6-NA, P = 0.0001) and a median OS of 17.8 mo (95% CI, 13.9-NA, P = 0.02). Men with a low DASM had a median TTTC of 12.2 mo (95% CI, 11.3-NA) and a median OS of NA (95% CI, 37.2 mo-NA), whereas those with a high DASM had a median TTTC of 6.9 mo (95% CI, 6.1-NA, P = 0.003) and a median OS of 17.8 mo (95% CI, 13.9-NA, P = 0.002). Conclusion: Findings on PSMA-targeted PET 2-4 mo after initiation of abiraterone or enzalutamide are associated with TTTC and OS. Development of new lesions or increasing intensity of radiotracer uptake at sites of baseline disease are poor prognostic findings suggesting shorter TTTC and OS.
Insights
Prostate-specific membrane antigen (PSMA)-targeted PET scans after starting abiraterone or enzalutamide therapy can predict treatment outcomes. Increased radiotracer uptake or new lesions on follow-up PET indicate poorer prognosis for time to therapy change and overall survival.
Area of Science:
- Nuclear Medicine
- Oncology
- Radiochemistry
Background:
- Prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) is a standard for prostate cancer imaging.
- Abiraterone and enzalutamide are common treatments for metastatic castration-resistant prostate cancer (mCRPC).
- Evaluating treatment response with PSMA-PET can offer prognostic information.
Purpose of the Study:
- To assess changes in PSMA-targeted PET uptake in men with mCRPC initiating abiraterone or enzalutamide.
- To correlate these changes with clinical outcomes, including time to therapy change (TTTC) and overall survival (OS).
Main Methods:
- Prospective, single-arm, 2-center exploratory clinical trial.
- 16 men with mCRPC received 18F-DCFPyL PET scans at baseline and 2-4 months after starting abiraterone or enzalutamide.
- Analysis included changes in SUVmax (DPSM and DASM) and correlation with TTTC and OS using Kaplan-Meier curves.
Main Results:
- Median TTTC was 9.6 months and median OS was 28.6 months.
- A mixed-but-predominantly-increased radiotracer uptake pattern correlated with shorter TTTC and OS.
- Higher delta-percent SUVmax (DPSM) and delta-absolute SUVmax (DASM) were associated with significantly shorter TTTC and OS (P < 0.0001 for DPSM, P = 0.003 for DASM).
Conclusions:
- PSMA-targeted PET findings 2-4 months after initiating abiraterone or enzalutamide predict TTTC and OS in mCRPC patients.
- Development of new lesions or increased radiotracer uptake intensity at baseline disease sites are poor prognostic indicators.
- PSMA-PET offers valuable prognostic information for guiding mCRPC treatment strategies.
