The comprehensive analysis of relationship between gut microbiome and treatment outcome of androgen deprivation therapy (ADT)-based treatment in patients with metastatic castration-sensitive and -resistant prostate cancer.

213 Background: Preclinical and clinical data from various types of cancer show that the gut microbiome can affect the outcome of treatments with immune checkpoint inhibitors or cytotoxic chemotherapies. However, the relationship between the microbiome and treatment outcomes in prostate cancer has remained unclear. Here, we present a comprehensive analysis of the relationship between the gut microbiome and treatment outcomes from a nationwide genome screening project (MONSTAR-SCREEN 1) in patients with metastatic castration-sensitive and -resistant prostate cancer (mCSPC and mCRPC). Methods: We performed 16S rRNA gene sequencing of fecal DNA from 73 mCSPC and 83 mCRPC patients before treatment. The microbiome data were compared using the Wilcoxon-Mann-Whitney test or Fisher’s exact test. Survival status and therapeutic efficacy of ADT based treatment were prospectively collected and estimated using the Kaplan-Meier method, and the log-rank test was used to compare survival in different strata. Results: Fecal samples from mCRPC had more Klebsiella and Enterobacteriaceae than those from mCSPC, whereas mCSPC had more Akkermansia and Bifidobacterium compared to mCRPC. Prior and concurrent usage of anti-biotics did not affect diversity of the amplicon sequence variants (ASVs), KEGG orthology and metabolism pathway representation. Anti-biotics also did not influence time to treatment failure (TTF) in mCRPC (HR:0.81, 95%CI:0.36–1.78) and mCSPC (HR:1.35, 95%CI:0.55–3.34). mCRPC had more diverse KEGG orthology compared to mCSPC ( p=0.0009), however, no statistical differences were observed in the ASV ( p=0.77) and metabolism pathway representation ( p=0.35) between mCRPC and mCSPC. High ASV tended to be associated with longer TTF rather than low ASV in both mCRPC (Adjusted HR:0.63, 95%CI:0.34–1.10) and mCSPC (Adjusted HR:0.66, 95%CI:0.31–1.40). mCRPC patients with high AVS also showed significant longer PSA-progression free survival than patients with low ASV (HR:053, 95%CI:0.28–0.99). Conclusions: This investigation revealed significant differences in the microbiome status of mCRPC compared to mCSPC. These differences and diversity might influence the outcomes of ADT based treatment in prostate cancer.