The human gut microbiota changes under the influence of environmental and genetic factors, affecting human health. Extensive studies have revealed that the gut microbiome is closely associated with many non-intestinal diseases. Among these, the influence of the gut microbiome on cancer biology and the efficacy of cancer therapy has attracted much attention. Prostate cancer cells are affected by direct contact with the microbiota of local tissues and urine, and a relationship between prostate cancer cells and the gut microbiota has been suggested. In the human gut microbiota, bacterial composition differs depending on prostate cancer characteristics, such as histological grade and castration resistance. Moreover, the involvement of several intestinal bacteria in testosterone metabolism has been demonstrated, suggesting that they may affect prostate cancer progression and treatment through this mechanism. Basic research indicates that the gut microbiome also plays an important role in the underlying biology of prostate cancer through multiple mechanisms owing to the activity of microbial-derived metabolites and components. In this review, we describe the evidence surrounding the emerging relationship between the gut microbiome and prostate cancer, termed the “gut-prostate axis.”

The final analysis of the phase 3 Targeted Investigational Treatment Analysis of Novel Anti-androgen (TITAN) trial showed improvement in overall survival (OS) and other efficacy endpoints with apalutamide plus androgen deprivation therapy (ADT) versus ADT alone in patients with metastatic castration-sensitive prostate cancer (mCSPC). As ethnicity and regional differences may affect treatment outcomes in advanced prostate cancer, a post hoc final analysis was conducted to assess the efficacy and safety of apalutamide in the Asian subpopulation. Event-driven endpoints were OS, and time from randomization to initiation of castration resistance, prostate-specific antigen (PSA) progression, and second progression-free survival (PFS2) on first subsequent therapy or death. Efficacy endpoints were assessed using the Kaplan-Meier method and Cox proportional-hazards models without formal statistical testing and adjustment for multiplicity. Participating Asian patients received once-daily apalutamide 240 mg ( n = 111) or placebo ( n = 110) plus ADT. After a median follow-up of 42.5 months and despite crossover of 47 placebo recipients to open-label apalutamide, apalutamide reduced the risk of death by 32% (hazard ratio [HR]: 0.68; 95% confidence interval [CI]: 0.42-1.13), risk of castration resistance by 69% (HR: 0.31; 95% CI: 0.21-0.46), PSA progression by 79% (HR: 0.21; 95% CI: 0.13-0.35) and PFS2 by 24% (HR: 0.76; 95% CI: 0.44-1.29) relative to placebo. The outcomes were comparable between subgroups with low- and high-volume disease at baseline. No new safety issues were identified. Apalutamide provides valuable clinical benefits to Asian patients with mCSPC, with an efficacy and safety profile consistent with that in the overall patient population.
Male ; Humans ; Prostatic Neoplasms/pathology* ; Androgen Antagonists/therapeutic use* ; Prostate-Specific Antigen ; Castration ; Prostatic Neoplasms, Castration-Resistant/drug therapy*

Ethnicity might be associated with treatment outcomes in advanced prostate cancer. This study aimed to evaluate the efficacy and safety of androgen deprivation therapy (ADT) combined with apalutamide in East Asians with metastatic castration-sensitive prostate cancer (mCSPC). The original phase 3 Targeted Investigational Treatment Analysis of Novel Anti-androgen (TITAN) trial was conducted at 260 sites in 23 countries. This subgroup analysis included patients enrolled in 62 participating centers in China, Japan, and Korea. Radiographic progression-free survival (PFS), time to prostate-specific antigen (PSA) progression, and PSA changes from baseline were compared between groups in the East Asian population. The intent-to-treat East Asian population included 111 and 110 participants in the apalutamide and placebo groups, respectively. The 24-month radiographic PFS rates were 76.1% and 52.3% in the apalutamide and placebo groups, respectively (apalutamide vs placebo: hazard ratio [HR] = 0.506; 95% confidence interval [CI], 0.302-0.849; P = 0.009). Median time to PSA progression was more favorable with apalutamide than placebo (HR = 0.210; 95% CI, 0.124-0.357; P < 0.001). Median maximum percentages of PSA decline from baseline were 99.0% and 73.9% in the apalutamide and placebo groups, respectively. The most common adverse event (AE) was rash in the apalutamide group, with a higher rate than that in the placebo group (37.3% vs 9.1%). The most common grade 3 or 4 AEs were rash (12 [10.9%]) and hypertension (12 [10.9%]) for apalutamide. The efficacy and safety of apalutamide in the East Asian subgroup of the TITAN trial are consistent with the global results.
Androgen Antagonists/adverse effects* ; Exanthema/chemically induced* ; Far East ; Humans ; Male ; Prostate-Specific Antigen ; Prostatic Neoplasms, Castration-Resistant/pathology* ; Thiohydantoins/adverse effects*