Prospective Evaluation of ¹⁸F-DCFPyL PET/CT in Biochemically Recurrent Prostate Cancer in an Academic Center: A Focus on Disease Localization and Changes in Management.

Abstract

¹⁸F-DCFPyL (2-(3-{1-carboxy-5-[(6-¹⁸F-fluoropyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid) is a promising PET radiopharmaceutical targeting prostate-specific membrane antigen (PSMA). We present our experience with this single-academic-center prospective study evaluating the positivity rate of ¹⁸F-DCFPyL PET/CT in patients with biochemical recurrence (BCR) of prostate cancer (PC). <b>Methods:</b> We prospectively enrolled 72 men (52-91 y old; mean ± SD, 71.5 ± 7.2) with BCR after primary definitive treatment with prostatectomy (<i>n</i> = 42) or radiotherapy (<i>n</i> = 30). The presence of lesions compatible with PC was evaluated by 2 independent readers. Fifty-nine patients had scans concurrent with at least one other conventional scan: bone scanning (24), CT (21), MR (20), ¹⁸F-fluciclovine PET/CT (18), or ¹⁸F-NaF PET (14). Findings from ¹⁸F-DCFPyL PET/CT were compared with those from other modalities. Impact on patient management based on ¹⁸F-DCFPyL PET/CT was recorded from clinical chart review. <b>Results:</b>¹⁸F-DCFPyL PET/CT had an overall positivity rate of 85%, which increased with higher prostate-specific antigen (PSA) levels (ng/mL): 50% (PSA < 0.5), 69% (0.5 ≤ PSA < 1), 100% (1 ≤ PSA < 2), 91% (2 ≤ PSA < 5), and 96% (PSA ≥ 5). ¹⁸F-DCFPyL PET detected more lesions than conventional imaging. For anatomic imaging, 20 of 41 (49%) CT or MRI scans had findings congruent with ¹⁸F-DCFPyL, whereas ¹⁸F-DCFPyL PET was positive in 17 of 41 (41%) cases with negative CT or MRI findings. For bone imaging, 26 of 38 (68%) bone or ¹⁸F-NaF PET scans were congruent with ¹⁸F-DCFPyL PET, whereas ¹⁸F-DCFPyL PET localized bone lesions in 8 of 38 (21%) patients with negative results on bone or ¹⁸F-NaF PET scans. In 8 of 18 (44%) patients, ¹⁸F-fluciclovine PET had located the same lesions as did ¹⁸F-DCFPyL PET, whereas 5 of 18 (28%) patients with negative ¹⁸F-fluciclovine findings had positive ¹⁸F-DCFPyL PET findings and 1 of 18 (6%) patients with negative ¹⁸F-DCFPyL findings had uptake in the prostate bed on ¹⁸F-fluciclovine PET. In the remaining 4 of 18 (22%) patients, ¹⁸F-DCFPyL and ¹⁸F-fluciclovine scans showed different lesions. Lastly, 43 of 72 (60%) patients had treatment changes after ¹⁸F-DCFPyL PET and, most noticeably, 17 of these patients (24% total) had lesion localization only on ¹⁸F-DCFPyL PET, despite negative results on conventional imaging. <b>Conclusion:</b>¹⁸F-DCFPyL PET/CT is a promising diagnostic tool in the work-up of biochemically recurrent PC, given the high positivity rate as compared with Food and Drug Administration-approved currently available imaging modalities and its impact on clinical management in 60% of patients.