Time-to-next treatment (TTNT) and overall survival (OS) among homologous recombination repair (HRR) positive and HRR negative patients with metastatic castration-resistant prostate cancer (mCRPC) initiating first-line (1L) therapy

80 Background: Several recurrent mutations that interfere with the HRR DNA damage signaling response pathway have been recently identified as novel biomarkers that may help optimize treatment for patients with mCRPC. There is limited real-world information on clinical outcomes, including TTNT and OS, among patients with mCRPC who initiate 1L, overall and by HRR mutation status in the United States. Methods: This study used the nationwide (de-identified) Flatiron Health – Foundation Medicine Inc. (FMI) Metastatic Prostate Cancer Clinico-Genomic Database (1/1/2011–12/31/2021). The de-identified data originated from approximately 280 US cancer clinics (~800 care sites). Patients who initiated 1L therapy (index date) on or after mCRPC diagnosis and had ≥1 HRR mutation test any time prior to or on the index date were included. Patients were excluded if they initiated a clinical trial drug in 1L or had