Metastasis-directed therapy in castration-refractory prostate cancer (MEDCARE): a non-randomized phase 2 trial.

Background: Patients diagnosed with metastatic castration-refractory prostate cancer (mCRPC) rely on a limited number of therapeutic agents resulting in a median survival of 2-3 years. A subgroup of those patients with mCRPC presents with oligoprogressive disease, with a limited number of progressive lesions while other metastases are still controlled by ongoing systemic treatment.

Methods: In this single arm prospective phase II trial, we aim to include 18 patients with oligoprogressive mCRPC (1-3 metastases and/or local recurrence) who will be treated with metastasis-directed therapy to all visible progressive lesions. Progression is based on conventional imaging, as the use of PSMA PET-CT is considered investigational. However all patients will undergo PSMA PET-CT and the images will be blinded until progression. Primary endpoint is the postponement of the start of next-line systemic treatment (NEST) and the additional clinical value of PSMA PET-CT. Recruitment of patients for this trial started in January 2020 and will be completed approximately by December 2020.

Discussion: In this phase 2 trial on oligoprogressive mCRPC, we will investigate the benefit of progression-directed therapy while continuing ongoing systemic treatment. We hypothesize that progression-directed therapy (PDT) with surgery or stereotactic body radiation therapy for these oligoprogressive lesions will postpone the start of next-line systemic treatment and therefore serve as a new or add-on therapy in the spectrum of treatments available for mCRPC. The results of this trial will serve as guidance for a later randomized phase 3 trial. All participants are given an information sheet and are required to give written informed consent. Results will be published in a peer-reviewed journal.

Trial Registration: This study is registered at ClinicalTrials.gov: NCT04222634 (December 18th 2019).