Introduction:

Despite improvements in early detection and primary therapy, biochemical recurrence of prostate cancer after curative intent primary therapy remains common. The advent of highly sensitive molecular imaging has allowed the identification of men with limited metastatic disease burden that might be more optimally treated with metastases-directed therapy rather than with systemic therapy.

The LOCATE (NCT02680041) and FALCON (NCT02578940) trials assessed the impact of ¹⁸F-fluciclovine positron emission tomography/computed tomography (PET/CT) on management of patients with prostate cancer recurrence after curative intent primary therapy. The goal was to analyze data from LOCATE and FALCON to evaluate the impact of ¹⁸F-fluciclovine on plans for androgen deprivation therapy (ADT) in patients with biochemical recurrence of prostate cancer.

Methods:

We performed a secondary analysis of LOCATE and FALCON data to characterize anatomical sites of disease recurrence and management decisions for patients with biochemical recurrence of prostate cancer who had an intended plan for treatment with ADT prior to undergoing ¹⁸F-fluciclovine PET/CT.

Data from 317 patients who underwent ¹⁸F-fluciclovine PET/CT as part of the LOCATE and FALCON trials were analyzed. All patients with a pre-scan plan for ADT either alone or in combination with another treatment modality were selected. PET/CT detection rates (DR) were determined at a per-patient level, for the prostate/prostate bed region, pelvic and extra-pelvic lymph nodes (LN), soft tissues and bones. The patients’ treatment plans post-scan were compared with the pre-scan plans and were stratified according to imaging findings.

Results:

146 patients had a pre-scan plan for ADT (60 as monotherapy and 86 in combination with another modality).
PET/CT detected lesions in 85 (58%) of patients planned for ADT. DR in the prostate/bed, pelvic LN, extra-pelvic LN, soft tissues and bone were 30%, 25%, 13%, 2.1% and 13%, respectively. Twenty-five (17%) patients had positivity confined to the prostate/bed, 21 (14%) had ¹⁸F-fluciclovine-positive pelvic nodes (± prostate/bed) but no other involvement and 39 (27%) had involvement outside the prostate/bed and pelvic nodes. 
Post-scan, 93/146 (64%) patients had a change in management (Figure 1), 55 (59%) of which were to abort ADT. Only 25% of the patients originally planned for ADT monotherapy still had a plan for ADT monotherapy post-scan. Patients with a post-scan plan for ADT monotherapy had the greatest proportion of extra-pelvic involvement (Figure 2). Local disease was most common in those whose plan was altered to abort ADT.

Conclusion:

Data from two prospective studies indicate that ¹⁸F-fluciclovine PET/CT influenced management plans for the majority of patients with a pre-scan plan that included ADT. Management plans were commonly amended to target salvage therapy for lesions identified with ¹⁸F-fluciclovine PET/CT, and consequently likely spared patients the morbidity associated with ADT.

Funding: Blue Earth Diagnostics Ltd