Clinical perspectives from ongoing trials in oligometastatic or oligorecurrent prostate cancer: an analysis of clinical trials registries.

purposeThanks to the introduction of more sensitive/specific imaging and minimally invasive treatment techniques, the oligometastatic state in prostate cancer (PCa) has attracted the interest of the uro-oncological community. We aim to identify and analyze trials across five registries to gain insights into the directions this field is moving.

methodsA systematic review of trials on oligometastatic PCa registered on ClinicalTrials.gov, ANZCTR, ISRCTN, Netherlands and UMIN Clinical Trials Registries was performed using the following keywords: 'prostate cancer' and 'oligo'. Data were extracted from ongoing/completed trials, with an unreported primary endpoint in a peer-reviewed journal, as of May until August, 2018.

resultsWe identified 41 trials on oligometastatic PCa. Twenty-four trials are conducted in North America and 14 in Europe. Up to 70% are phase I or II trials and < 10% (n = 4) are in phase III. Less than 50% (n = 17) are randomized controlled trials. Oligometastases are PET detected in 25 trials. Studies on synchronous oligometastatic (n = 12; 29%) or oligorecurrent (n = 14; 34%) PCa are equally represented, the remainder focus on mixed states (n = 15; 37%). The majority (n = 39; 95%) of trials investigate local treatment options (RP: 5; RT: 9; RP ± RT: 7; metastasis-directed therapy: 28) with (72%) or without (28%) systemic treatment. The remaining two are imaging studies. Progression-free (PFS; 17/41; 41%) or overall survival (OS; 3/41; 7%) is defined as primary endpoint in half of all trials, others are 'safety/toxicity' or 'PSA response'.

conclusionsWith 41 ongoing trials, there is great interest in oligometastatic PCa. Most trials address local ablative treatments both for prostate and/or metastases, typically by radiotherapy, and several attempts to determine the benefit of adding systemic therapy. The field will hopefully have definitive answers after completion of four ongoing phase III trials.