Preliminary results of a two stage phase II study of 18F-DCFPyL PET-MR for enabling oligometastases ablative therapy in subclinical prostate cancer.
Journal Articles
Overview
Research
Identity
Additional Document Info
View All
Overview
abstract
250 Background: 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 study design was employed. Stage 1 included 12 response evaluable patients, requiring 1 or more responses in the absence of grade 3+ toxicities to proceed to stage 2 (additional 25 response evaluable patients). Results: After a median of 58 months (range 29-120) post MLT, 20 patients underwent PET-MR/CT to have 12 response evaluable patients. Median PSA at enrollment was 1.3 ng/mL (range 0.4-2.8). Three patients had negative PET-MR/CT, while 17 had positive scans, of which 12 (60%) were amenable to response evaluable ablation. The median number of detected lesions in those treated was 2 (range 1-5). Ten patients underwent SABR (27-30 Gy/3 fractions) and 2 had surgery. One patient (8%) had complete and 4 (33%) had partial PSA responses at a median of 3.3 months (range 2.8-6.0) after ablation, while the remaining 7 (59%) did not have biochemical response. No grade 3+ toxicities were observed. Conclusions: 18F-DCFPyL PET/MR has high detection rates in men with rising PSA after MLT. We observed favorable early results with SABR or surgery (41% RR). Trial completion will inform if this approach offers potential for cure in an early molecularly-defined PC oligometastatic state. Clinical trial information: NCT03160794.
