Terbinafine for Biochemically Recurrent Prostate Cancer (TerbinaPro)

Key Inclusion Criteria: * Patients after definitive treatment for localized prostate cancer and exhaustion of standard curative options (i.e. after prostatectomy and adjuvant /salvage radiotherapy; definite radiotherapy, brachytherapy; additional previous Stereotactic Body Radiation Therapy (SBRT) to treat visible oligometastatic disease also allowed as long as confirmed Prostate-specific antigen (PSA) progression is present after SBRT) * Non-castrate levels of testosterone (≥ 5 nmol/l; previous androgen deprivation therapy (ADT) allowed as long as testosterone levels have recovered before study entry) * No evidence of distant metastatic disease on conventional imaging (Computed Tomography (CT) and bone scan) or Prostate-Specific Membrane Antigen (PSMA) Positron Emission Tomography (PET) CT. * Patients with PSMA positive lymph nodes on PSMA PET CT can still be included if the short axis of the largest lymph node is \< 20 mm for lymph nodes below aortic bifurcation or \< 10 mm above the aortic bifurcation. * PSA of ≥1 ng/ml after radical prostatectomy or ≥2 ng/ml above the nadir (with recovered testosterone) after primary radiotherapy; confirmation of rising PSA in at least a second measurement at least 2 weeks apart * Patient declining start of ADT and /or an androgen receptor pathway inhibitor (ARPI) and/or judged as not in need of immediate ADT/ARPI start by treating physician Key Exclusion Criteria: * Pre-existing known chronic or acute liver disease * Known history of systemic lupus erythematosus or any form of lupus (including cutaneous, drug-induced, or lupus nephritis) * Pure neuroendocrine/small-cell histologic variant of prostate cancer