Diagnostic performance of 18F-fluciclovine PET/CT for regional lymph node metastases in patients with primary prostate cancer: a multicenter phase II clinical trial.

OBJECTIVE: This multicenter, phase II clinical trial evaluated the diagnostic performance of 18F-fluciclovine, a novel amino acid for positron-emission tomography (PET), for detection of small lymph node metastases with short-axis diameters of 5-10 mm in patients with prostate cancer. METHODS: Patients with prostate cancer were eligible after screening of laboratory tests and pelvic contrast-enhanced computed tomography (CT). Pelvic region 18F-fluciclovine PET/CT was then acquired within 28 days and dissection of regional lymph nodes was performed within 60 days of pelvic contrast-enhanced CT. Diagnostic performance of 18F-fluciclovine-PET/CT was evaluated by comparison with standard histopathology of lymph nodes. RESULTS: In a total of 28 patients, 40 regional lymph nodes with short-axis diameters of 5-10 mm were eligible for efficacy evaluation; seven of these showed metastases confirmed by histopathology. The sensitivity of 18F-fluciclovine PET/CT was 57.1% (4/7). All four true positive lymph nodes detected by 18F-fluciclovine PET/CT had a metastatic lesion with a long-axis diameter of ≥7 mm and a high proportion of cancer volume (60-100%) according to pathology evaluation. The specificity, diagnostic accuracy, positive predictive value, and negative predictive value of 18F-fluciclovine PET/CT in lymph node-based analysis were 84.8% (28/33), 80.0% (32/40), 44.4% (4/9), and 90.3% (28/31), respectively. No clinically significant adverse events occurred. CONCLUSIONS: 18F-fluciclovine PET/CT detected small lymph node metastases; however it also showed positive findings in benign lymph nodes. Refinement of the image assessment criteria may improve the diagnostic performance of 18F-fluciclovine PET/CT for small lymph node metastases in patients with prostate cancer.

Diagnostic performance and safety of NMK36 (trans-1-amino-3-[18F]fluorocyclobutanecarboxylic acid)-PET/CT in primary prostate cancer: multicenter Phase IIb clinical trial.

OBJECTIVE: We performed a multicenter Phase IIb clinical trial of NMK36, a novel amino acid analog for positron emission tomography containing trans-1-amino-3-[(18)F]fluorocyclobutanecarboxylic acid, to evaluate its safety and diagnostic performance for primary prostate cancer. METHODS: Sixty-eight subjects with primary prostate cancer scheduled for radical prostatectomy or hormone therapy underwent whole-body positron emission tomography/computed tomography after injection of NMK36. The diagnostic performances of NMK36-positron emission tomography/computed tomography were evaluated for (i) regional lymph node metastasis: comparison with contrast-enhanced computed tomography under setting reference standard (histopathology or 6-month follow-up), (ii) bone metastasis: concordance rate with conventional imaging (combination of bone scintigraphy and contrast-enhanced computed tomography) and (iii) primary lesion: comparison with histopathological findings. RESULTS: The accuracy of NMK36-positron emission tomography/computed tomography and contrast-enhanced computed tomography for regional lymph node metastasis were 85.5 and 87.3%, respectively. NMK36-positron emission tomography/computed tomography showed positive findings for regional lymph nodes with short-axis diameters of 5-9 mm at 23 regions in 13 patients of hormone therapy cohort, but they were not confirmed with reference standard in this study. The concordance rate of NMK36-positron emission tomography/computed tomography with conventional imaging for bone metastases was 83.3%, and seven patients had positive findings only by NMK36-positron emission tomography/computed tomography. The sensitivity and specificity of NMK36-positron emission tomography/computed tomography for primary lesion in six-segment analysis was 92.5 and 90.1%, respectively. Seven of non-serious adverse events were observed in six patients. CONCLUSIONS: This study showed the comparable diagnostic performance of NMK36-positron emission tomography/computed tomography compared with conventional imaging. Some lesions of lymph node and bone were positive solely by NMK36-positron emission tomography/computed tomography, which needs to be confirmed with reference standard in future study to evaluate the usefulness of NMK36-positron emission tomography/computed tomography in staging prostate cancer.