PET/CT Accurately Localizes Recurrent Prostate Cancer

Imaging with ⁶⁸Ga-PSMA11 PET/CT is highly accurate in localizing recurrent prostate cancer (PCa), according to data that presented at the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois, on Monday, June 4.¹ In addition, salvage therapy guided by ⁶⁸Ga-PSMA11 PET/CT resulted in high biochemical response rates.

In a phase 2/3 prospective trial (ClinicalTrials.gov Identifer: NCT02940262) conducted by Wolfgang Fendler, MD, and colleagues at the David Geffen School of Medicine at the University of Califnoria, Los Angeles, patients who experienced biochemical recurrence following radical prostatectomy (205 patients) or radiation therapy (45 patients) for PCa underwent ⁶⁸Ga-PSMA11 PET/CT. Lesions were validated in 51% of PET/CT-positive patients by histopathology (33 patients), imaging (62 patients), and/or PSA after targeted radiation therapy (9 patients). PSA response following ⁶⁸Ga-PSMA11 PET/CT guided focal salvage therapy (surgery/radiotherapy) was recorded for 23 of 25 patients.

The positive predictive value (PPV) by histopathology was 85% on a patient base (primary endpoint). PPV as determined by any type of validation was 89% on a patient base and 91% on a region base. ⁶⁸Ga-PSMA11 PET/CT localized recurrent PCa in 197 (79%) of 250 patients. The rate varied by PSA (in ng/mL): 41% for PSA below 0.5; 66% for 0.5 to less than 1.0; 86% for 1.0 to less than 2.0; 96% for 2.0 to less than 5.0; and 99% for 5.0 ng/mL or higher.

⁶⁸Ga-PSMA11 PET/CT localized 35% of lesions in the prostate bed, 61% in the pelvis, 35% outside the pelvis, and 31% in bone.

Following salvage therapy alone guided by ⁶⁸Ga-PSMA11 PET/CT, 18 patients (78%) had a PSA drop of 50% of more and 7 (30%) had a complete biochemical response (PSA undetectable).

Read more of Cancer Therapy Advisor‘s coverage of the American Society of Clinical Oncology (ASCO) 2018 meeting by visiting the conference page.

Reference

1. Fendler W, Calais J, Gartmann J, et al. Accuracy of ⁶⁸Ga-PSMA11 PET/CT on recurrent prostate cancer: Preliminary results from a phase 2/3 prospective trial. J Clin Oncol. 2018: 36, (suppl; abstr 5001). Presented at 2018 ASCO Annual Meeting; June 1-5, 2018; Chicago, IL.