Preliminary results of a two stage phase II study of 18F-DCFPyL PET-MR for enabling oligometastases ablative therapy in subclinical prostate cancer.

250Background: Despite maximal local therapies (MLT) (radical prostatectomy followed by radiotherapy [RT]), 20-30% of men will have incurable progression of prostate cancer (PC). Most recurrences in this scenario are characterized by continuous PSA rises and failure of standard imaging (bone scan [BS] and computed tomography [CT]) to detect recurrence sites. We conducted a phase II trial for men with rising PSA after MLT using 18F-DCFPyL PET-MR followed by targeted ablation of PET positive foci. We report the results of our pre-defined analysis. Methods: Patients with rising PSA (0.43.0 ng/mL) after MLT, negative BS/CT and no prior salvage ADT were eligible. All patients underwent 18F-DCFPyL PET-MR followed by immediate PET-CT acquisition. Those with limited disease, where possible, underwent stereotactic ablative RT (SABR) or surgery. No ADT was used. The primary endpoint was biochemical response rate (complete [undetectable PSA] or partial [PSA decline ≥50% compared to baseline]). A Simon’s two stage st...