Impact of proton pump inhibitors on the efficacy of androgen receptor signaling inhibitors in metastatic castration-resistant prostate cancer patients.

BACKGROUND: Proton pump inhibitors (PPIs) are widely used due to their affordability and minimal severe side effects. However, their influence on the efficacy of cancer treatments, particularly androgen receptor signaling inhibitors (ARSIs), remains unclear. This study investigates the impact of PPI usage on the treatment outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC). METHODS: A total of 117 mCRPC patients were retrospectively analyzed and divided into two groups based on the concomitant use of PPI at the initiation of ARSI treatment: PPI+ (n = 38) and PPI- (n = 79). Patient characteristics, including age at ARSI treatment administered, prostate-specific antigen (PSA) value at ARSI treatment administered, International Society of Urological Pathology grade group at prostate biopsy, metastatic site at ARSI treatment administered, prior docetaxel (DTX) treatment, and type of ARSI (abiraterone acetate or enzalutamide) were recorded. Progression-free survival (PFS), overall survival (OS), and PSA response rates were compared between the two groups. Patients were further stratified by clinical background to compare PFS and OS between the two groups. RESULTS: The PPI- group exhibited significantly extended PFS and a trend toward improved OS. For PSA response (reduction of 50% or more from baseline), the rates were 62.3% and 45.9% in the PPI- group and the PPI+ group, respectively. For deep PSA response (reductions of 90% or more from baseline), the rates were 36.4% and 24.3% in the PPI- group and the PPI+ group, respectively. The effects were consistent across subgroups divided by prior DTX treatment and type of ARSI administered. CONCLUSIONS: The administration of PPIs appears to diminish the therapeutic efficacy of ARSIs in mCRPC patients. Further prospective studies are needed to confirm these findings and explore the biological mechanisms involved.

NR5A2/HSD3B1 pathway promotes cellular resistance to second-generation antiandrogen darolutamide.

This study investigated cellular mechanisms in steroidogenesis responsible for treatment resistance to the novel antiandrogen agent darolutamide in prostate cancer. HSD3B1 was overexpressed in darolutamide-resistant cells and induced by darolutamide treatment and AR knockdown. Inversely, HSD3B1 knockdown increased cellular sensitivity to darolutamide. Similarly, its upstream regulator NR5A2 was up-regulated in darolutamide-resistant cells and induced by darolutamide treatment and AR knockdown. Inversely, NR5A2 knockdown and NR5A2 inhibitor ML180 decreased expression of various steroidogenic enzymes including HSD3B1, leading to increased cellular sensitivity to darolutamide. The NR5A2/HSD3B1 pathway promoted cellular resistance to darolutamide and targeting NR5A2/HSD3B1 pathway is a promising therapeutic strategy to overcome darolutamide resistance.

Clinical features and oncological outcomes of bladder cancer microsatellite instability.

OBJECTIVES: Excellent anticancer effect for solid tumors with microsatellite instability (MSI)-high by anti-PD-1 antibody has been reported. In this study, we investigated the clinical impact of MSI status in bladder cancer. METHODS: This study included 205 Japanese patients who underwent transurethral resection for bladder cancer between 2005 and 2021. The prevalence rates of microsatellite stable (MSS), MSI-low (MSI-L), and MSI-high (MSI-H) were determined using molecular testing. We examined the association of MSI status (MSS versus MSI-L/H) with clinicopathological characteristics and oncological outcomes. RESULTS: MSI-L/H tumors were associated with higher T-category in non-muscle invasive bladder cancer (NMIBC). Additionally, MSI-L/H tumors were associated with a higher risk of intravesical recurrence in NMIBC patients treated with intravesical bacillus Calmette-Guérin (BCG) but not with non-BCG therapy. CONCLUSIONS: This study suggested that the MSI status might serve as a predictive marker for intravesical recurrence after BCG intravesical therapy in NMIBC and highlighted an unmet need for an alternative treatment in patients with MSI-L/H tumors.

Validation of schedules for optimal prostate-specific antigen monitoring after radical prostatectomy.

BACKGROUND: Early detection of biochemical recurrence (BCR) after radical prostatectomy (RP) is crucial for early treatment and improving survival outcomes. The optimal prostate-specific antigen (PSA) monitoring remains unclear, and several models have been proposed. We aimed to externally validate four models for optimal PSA monitoring after RP and propose modifications to improve them. METHODS: We reviewed the clinicopathological data of 896 patients who underwent robot-assisted RP between 2009 and 2022. We examined all PSA values and estimated the PSA value for four monitoring schedules at each time point in the virtual follow-up. We defined the ideal PSA for BCR detection between 0.2 and 0.4 ng/mL. RESULTS: During the median follow-up of 21.4 months, 128 (14.3%) patients presented BCR. The original and modified Keio models, National Cancer Center Hospital model, and American Urological Association/American Society for Radiation Oncology model detected BCR in 14 (10.9%), three (2.3%), 12 (9.4%), and 11 (8.6%) patients with PSA >0.4 ng/mL. Most patients experienced BCR detected with PSA >0.4 ng/mL during the first year postoperative. The modification of interval within 6 months postoperative avoided BCR detection with PSA >0.4 ng/mL within the first year postoperative in 8/9 (88.9%), 1/2 (50.0%), 5/6 (83.3%), and 4/4 (100%) for the original and modified Keio models, National Cancer Center Hospital model, and American Urological Association/American Society for Radiation Oncology model, respectively. CONCLUSION: We validated four models for PSA monitoring after RP to detect BCR and suggested modifications to avoid detections out of the desired range of PSA. These modifications could help to establish an optimal PSA monitoring schedule after RP.

Fusion-targeted biopsy significantly improves prostate cancer detection in biopsy-naïve men.

OBJECTIVE: The precise diagnosis of prostate cancer (PC) is crucial to avoid underdiagnosis, overdiagnosis, and overtreatment. We aimed to compare clinically significant PC (csPC) detection between MRI/ultrasound fusion-targeted prostate (TBx) compared to systematic biopsy (SBx) in biopsy-naïve Japanese men. METHODS: We included patients with suspect PC due to elevated PSA level or abnormal digital rectal examination, or both. csPC was defined as International Society Urological Pathology (ISUP) grade group ≥2 (csPC-A) and ISUP grade group ≥3 (csPC-B). RESULTS: This study included 143 patients. Overall PC detection was 66.4% for SBx and 67.8% for MRI-TBx. MRI-TBx presented a significantly higher rate of csPC detection (csPC-A 67.1% vs. 58.7%, p = 0.04, and csPC-B 49.6% vs. 39.9%, p < 0.001) and significantly lower detection of non-csPC-A (0.6% vs. 6.7%). Importantly, MRI-TBx missed 4.9% (7/143) of csPC-A and only 0.7% (1/143) of csPC-B. On the other hand, SBx alone missed 13.3% (19/143) of csPC-A and 4.2% (6/143) of csPC-B. CONCLUSION: MRI-TBx significantly outperformed 12-cores SBx for csPC detection and decreased non-csPC detection in biopsy-naive men. Performing MRI-TBx without SBx would have missed some csPC, supporting that MRI-TBx synergizes with SBx to increase csPC detection.

Extracellular vesicles expressing CEACAM proteins in the urine of bladder cancer patients.

Early detection and long-term monitoring are important for urothelial carcinoma of the bladder (UCB). Urine cytology and existing markers have insufficient diagnostic performance. Here, we examined medium-sized extracellular vesicles (EVs) in urine to identify specific markers for UCB and evaluated their usefulness as diagnostic material. To identify specific markers in urinary EVs derived from UCB, we undertook shotgun proteomics using urine from four UCB patients and four healthy subjects. Next, 29 healthy specimens, 18 noncancer specimens, and 33 UCB specimens, all from men, were analyzed for urinary EVs by flow cytometry to evaluate the diagnostic performance of UCB-specific EVs. Nanoparticle-tracking analysis indicated that the size of EVs extracted from urine was mostly <400 nm. By shotgun proteomics, we detected several proteins characteristic of UCB and found that carcinoembryonic antigen-related adhesion molecule (CEACAM) proteins were increased in patients. Flow cytometric analysis revealed that the degree of expression of CEACAM1, CEACAM5, and CEACAM6 proteins on the surface of EVs varied among patients. Extracellular vesicles expressing CEACAM proteins also expressed mucin 1, suggesting that they were derived from tumorigenic uroepithelial cells. The number of EVs expressing CEACAM1, 5, and 6 proteins was significantly increased in UCB (mean ± SD, 8.6 ± 13%) compared to non-UCB (0.69 ± 0.46) and healthy (0.46 ± 0.34) by flow cytometry. The results of receiver operating characteristic (ROC) analysis showed a good score of area under the ROC curve of 0.907. We identified EVs that specifically express CEACAM proteins in urine and have potential for diagnostic applications. These EVs are potential targets in a new liquid biopsy test for UCB patients.

Clinical impact of HSD3B1 polymorphism by metastatic volume and somatic HSD3B1 alterations in advanced prostate cancer.

This study aimed to investigate the significance of HSD3B1 gene status including germline polymorphism and somatic alterations in prostate cancer. Patients with prostate cancer treated with androgen-deprivation therapy, as well as tissues from metastatic prostate cancer, were included. Genomic DNA was extracted from cancer tissues and whole blood samples, and HSD3B1 (rs1047303, 1245C) was genotyped by Sanger sequencing. The association of HSD3B1 genotype with progression-free survival according to metastatic volume was examined. Copy number alteration and gene expression of HSD3B1 were examined in prostate cancer cells and public datasets. Among 194 patients, 121 and 73 patients were categorized into low- and high-volume diseases respectively. In multivariate analysis, the adrenal-permissive genotype (AC/CC) was significantly associated with increased risk of progression compared with the adrenal-restrictive genotype (AA) in low volume, but not high-volume diseases. Somatic mutation in HSD3B1 was detected at least in two cases of castration-resistant prostate cancer tissues. HSD3B1 amplification and overexpression were detected in castration-resistant prostate cancer cells and tissues. The current findings suggest that both germline and somatic alterations of HSD3B1 may cooperatively promote castration resistance in prostate cancer and HSD3B1 as a promising biomarker for precision medicine, warranting further investigations.

Validation of models predicting lymph node involvement probability in patients with prostate cancer.

OBJECTIVES: There are many models to predict lymph node involvement in patients with prostate cancer. We aimed to externally validate several models in a Japanese cohort. METHODS: We considered patients who were treated with robotic-assisted radical prostatectomy with extended pelvic lymph node dissection for prostate cancer. The risk of lymph node involvement was calculated for each patient in several models. Model performance was assessed by calculating the receiver operating characteristic curve and the area under the curve, calibration plots, and decision curve analyses. RESULTS: We identified lymph node involvement in 61 (18.4%) of the 331 considered patients. Patients with lymph node involvement had a higher prostate-specific antigen level, percentage of positive biopsy cores, primary Gleason grade, Gleason group grade, and clinical T-stage category. The Memorial Sloan Kettering Cancer Center web calculator presented the highest area under the curve (0.78) followed by the Yale formula area under the curve (0.77), the updated version of Briganti nomogram of 2017 area under the curve (0.76), and the updated version of the Partin table by Tosoian et al. had an area under the curve of 0.75. However, the 95% confidence interval for these models overlapped. The calibration plot showed that the Memorial Sloan Kettering Cancer Center web calculator and the updated version of the Briganti nomogram calibrated better. In the decision curve analyses, all models showed net benefit; however, it overlapped among them. However, the Memorial Sloan Kettering Cancer Center web calculator and the updated Briganti nomogram presented the highest net benefit for lymph node involvement risks <35%. CONCLUSION: Models predicting lymph node involvement were externally validated in Japanese men. The Memorial Sloan Kettering Cancer Center web calculator and the updated Briganti nomogram of 2017 were the most accurate performing models.

Gene amplification of YB-1 in castration-resistant prostate cancer in association with aberrant androgen receptor expression.

Although Y-box binding protein-1 (YB-1) is known to be overexpressed in prostate cancer, especially castration-resistant prostate cancer (CRPC), the mechanism of its overexpression remains unclear. We aimed to elucidate the mechanism of YB-1 overexpression in CRPC. Gene amplification in CRPC cells and tissues was examined by public database analysis, and digital PCR. The significance of YB-1 amplification for the YB-1/androgen receptor (AR) axis and prognosis was examined by public database analysis and immunohistochemistry. YB-1 amplification was mainly observed in CRPC tissues by public database analysis and confirmed in CRPC cells and tissues by digital PCR. Expression of YB-1 was increased in CRPC tissues compared with treatment-naïve tissues. Furthermore, YB-1 and phosphorylated YB-1 levels were associated with AR and AR V7 expression levels. Finally, YB-1 amplification was associated with poor outcomes in CRPC. Taken together, the present findings suggest that YB-1 amplification contributes to progression to CRPC through regulation of AR and AR V7 expressions, and that YB-1 is a promising therapeutic target in CRPC.

Genomic characteristics revealed by targeted exon sequencing of testicular germ cell tumors in Japanese men.

OBJECTIVE: To investigate the somatic mutation profiles of testicular germ cell tumors in Japanese men. METHODS: We analyzed the somatic missense mutation profile of testicular germ cell tumors among 21 Japanese men with seminoma (n = 14), pure embryonic carcinoma (n = 3) and mixed testicular germ cell tumor (n = 4) by targeted next-generation sequencing of 409 cancer-related genes covering 1.23 Mb of the genome. RESULTS: We identified a total of 22 missense mutations in 21 primary testicular germ cell tumor samples (0.89 mutations/Mb), of which seven mutations were confirmed to be absent from the germline. KIT:p.Asn822Tyr, KIT:p.Leu576Pro, PIK3CA:p.Glu542Lys and FBXW7:p.Arg505His were statistically and functionally potential. A total of 18 missense mutations were previously unknown in testicular germ cell tumors. PDGFRA amplification from one patient with seminoma was detected. KIT, BCR,PIK3CG, PIK3CA and PDGFRA mutations involved in aberrant signaling of the KIT-PI3K-AKT pathway was detected in 27.3% of detected mutations. CONCLUSIONS: The present investigation identified a low mutation rate in testicular germ cell tumors among Asian patients, 18 novel mutations and PDGFRA amplification. Limitations of the present study are the small sample and missing normal DNA for some testicular germ cell tumors.

Adverse Events of Cabozantinib Plus Nivolumab Versus Ipilimumab Plus Nivolumab.

INTRODUCTION: Recently, many agents and combinations for metastatic and advanced renal cell carcinoma have been approved. This study aims to highlight the comprehensive differences in adverse events (AEs) between cabozantinib (CAB) plus nivolumab (NIVO) and ipilimumab (IPI) plus NIVO based on a real-world big dataset. MATERIAL AND METHODS: We downloaded AE datasets of IPI + NIVO and CAB + NIVO from the Food and Drug Administration Adverse Event Reporting System database. We used the Medical Dictionary for Regulatory Activities to treat each AE as a preferred term and grouped it into the System Organ Class (SOC). We performed logistic regression analyses to compare IPI + NIVO and CAB + NIVO. RESULTS: The incidence rates of 7 types of toxicities were higher for CAB + NIVO than for IPI + NIVO. On the other hand, the incidence rates of 3 types of toxicities were higher for IPI + NIVO than for CAB + NIVO. Serious AEs were higher in patients receiving IPI + NIVO. CONCLUSION: Our findings suggest that both combination therapies presented a disproportionate distribution of toxicities in several SOC. These findings may help clinicians select suitable therapy for the individual and improve the safety profile in patients with advanced renal cell carcinoma receiving NIVO + IPI and NIVO + CAB in a real-world setting.

Importance of 3ß-hydroxysteroid dehydrogenases and their clinical use in prostate cancer.

Androgen receptor signaling is crucial for the development of treatment resistance in prostate cancer. Among steroidogenic enzymes, 3ß-hydroxysteroid dehydrogenases (3ßHSDs) play critical roles in extragonadal androgen synthesis, especially 3ßHSD1. Increased expression of 3ßHSDs is observed in castration-resistant prostate cancer tumors compared with primary prostate tumors, indicating their involvement in castration resistance. Recent studies link 3ßHSD1 to resistance to androgen receptor signaling inhibitors. The regulation of 3ßHSD1 expression involves various factors, including transcription factors, microenvironmental influences, and posttranscriptional modifications. Additionally, the clinical significance of HSD3B1 genotypes, particularly the rs1047303 variant, has been extensively studied. The impact of HSD3B1 genotypes on treatment outcomes varies according to the therapy administered, suggesting the potential of HSD3B1 genotyping for personalized medicine. Targeting 3ßHSDs may be a promising strategy for prostate cancer management. Overall, understanding the roles of 3ßHSDs and their genetic variations may enable the development and optimization of novel treatments for prostate cancer.

Oxidative stress in peroxisomes induced by androgen receptor inhibition through peroxisome proliferator-activated receptor promotes enzalutamide resistance in prostate cancer.

Androgen receptor (AR)-targeting therapy induces oxidative stress in prostate cancer. However, the mechanism of oxidative stress induction by AR-targeting therapy remains unclear. This study investigated the mechanism of oxidative stress induction by AR-targeting therapy, with the aim to develop novel therapeutics targeting oxidative stress induced by AR-targeting therapy. Intracellular reactive oxygen species (ROS) was examined by fluorescence microscopy and flow cytometry analysis. The effects of silencing gene expression and small molecule inhibitors on gene expression and cytotoxic effects were examined by quantitative real-time PCR and cell proliferation assay. ROS induced by androgen depletion co-localized with peroxisomes in prostate cancer cells. Among peroxisome-related genes, PPARA was commonly induced by AR inhibition and involved in ROS production via PKC signaling. Inhibition of PPARα by specific siRNA and a small molecule inhibitor suppressed cell proliferation and increased cellular sensitivity to the antiandrogen enzalutamide in prostate cancer cells. This study revealed a novel pathway by which AR inhibition induced intracellular ROS mainly in peroxisomes through PPARα activation in prostate cancer. This pathway is a promising target for the development of novel therapeutics for prostate cancer in combination with AR-targeting therapy such as antiandrogen enzalutamide.

Salvage robot-assisted radical prostatectomy after carbon ion radiotherapy to the prostate.

PURPOSE: This study presents the surgical and oncological outcomes of salvage robot-assisted radical prostatectomy (RARP) after carbon ion radiotherapy at a single institution. METHODS: Patients who underwent salvage RARP for local recurrence after carbon ion radiotherapy at Kyushu University Hospital between 2020 and 2023 were included. A single surgeon performed salvage RARP with extended pelvic lymph node dissection. Clinicopathological characteristics and perioperative and postoperative outcomes were prospectively collected and electronically recorded. RESULTS: Ten cases were included. The preoperative clinical T-stage was T2, except for one case with T3a. The median console time was 171 min (range, 135-226 min). No severe perioperative or postoperative complications were noted. The pathological T-stage was T2, T3a, and T3b in four, four, and two cases, respectively. Biochemical recurrence was observed in one patient at 31.2 months after surgery. For patients with more than 1 year of follow-up, urinary continence recovery with ≤1 pad was achieved in two cases within 1 year, whereas four cases did not recover urinary continence within 1 year. CONCLUSIONS: This case series demonstrated the feasibility of salvage RARP after carbon ion radiotherapy. Although the urinary continence recovery was modest, short-term disease control was favorable.

Adverse Events of Abiraterone Acetate vs Enzalutamide.

INTRODUCTION: This study aimed to highlight the comprehensive differences in adverse events between abiraterone and enzalutamide based on a big data data set. METHODS: We downloaded adverse event data sets of abiraterone and enzalutamide from the Food and Drug Administration Adverse Event Reporting System database. We used the Medical Dictionary for Regulatory Activities to treat each adverse event as a preferred term and grouped it into the System Organ Class. Logistic regression analyses were performed to compare abiraterone and enzalutamide. RESULTS: In total, we extracted 59,680 data sets. After exclusion by criteria, we included 26,015 reports on enzalutamide and 7,507 on abiraterone. Enzalutamide and abiraterone presented different toxicity profiles in most System Organ Classes. Overall, the reporting odds ratio indicated a higher incidence rate of serious adverse events for abiraterone than enzalutamide. CONCLUSIONS: In conclusion, our findings suggest that both drugs present a discrete and nonoverlapping toxicity profile that varies by System Organ Class and patient age. This data set confirms, for the most part, what has been reported in clinical trials as well as true real-world reports.

Comparison of Testosterone Level of Seminal Vesicle Fluid in Patients With Prostate Cancer Versus Other Malignancies.

BACKGROUND/AIM: Testosterone is essential for prostate cancer development and growth. This study aimed to investigate the relationship between testosterone in seminal vesicles and prostate cancer incidence and its malignant phenotype. PATIENTS AND METHODS: After obtaining institutional review board approval, seminal vesicle fluid samples were collected from patients who underwent prostatectomy or cystectomy. Pathological review demonstrated that 26 patients had benign prostate tissue and 149 had prostate cancer. First, testosterone levels in seminal vesicle fluid from benign prostate and prostate cancer samples were compared. Next, the relationship between pathological stage, International Society of Urological Pathology (ISUP) score, and testosterone concentrations in seminal vesicle fluid in the prostate cancer group were examined. RESULTS: Testosterone in seminal vesicles was significantly higher in the prostate cancer group [median (range), 1.94 (0.17-4.32) ng/ml] than in the benign prostate group (mainly bladder cancer) [1.45 (0.60-2.78) ng/ml] (p=0.001). Testosterone in seminal vesicles showed no difference in relation to pathological stage (pT2 vs. pT3) or ISUP score (12 vs. 345) (p=0.480 and p=0.964, respectively). Neoadjuvant chemotherapy for other cancers (e.g., bladder or rectal cancer) significantly reduced testosterone in seminal vesicles (p=0.013). Multivariate regression analysis revealed that testosterone in seminal vesicles was significantly correlated with prostate cancer, and not with neoadjuvant chemotherapy (p=0.023, p=0.457, respectively). CONCLUSION: Testosterone in seminal vesicles may contribute to prostate cancer incidence, but has no relationship with pathological grading.

Improved urinary continence recovery after robot-assisted radical prostatectomy with lateral pelvic fascia preservation.

The novel technique of lateral pelvic fascia preservation (LPFP) in robot-assisted radical prostatectomy (RARP) has been reported to improve urinary continence recovery. We aimed to investigate surgical and oncological outcomes after RARP using the LPFP technique and compare them with conventional RARP. This study included patients who underwent RARP with and without the LPFP technique. Time to urinary continence recovery was compared between the LPFP and non-LPFP groups using univariate, multivariate, and propensity-score matched analysis. Perioperative and postoperative outcomes were compared between the two groups using univariate analysis. We included 139 patients who underwent RARP, 68 in the LPFP group and 71 in the non-LPFP group. The LPFP technique was associated with a shorter time to urinary continence recovery, a shorter operative time and lower estimated blood loss. Surgical and oncological outcomes, including complications, pathological T-stage, surgical margin status, and biochemical recurrence-free survival, were comparable between the two groups. This study demonstrated that the LPFP technique improves urinary continence recovery and operative times without compromising surgical and oncological outcomes. The use of this technique in patients with clinically localized prostate cancer is recommended.

Validation of user-friendly models predicting extracapsular extension in prostate cancer patients.

Objective: There are many models to predict extracapsular extension (ECE) in patients with prostate cancer. We aimed to externally validate several models in a Japanese cohort. Methods: We included patients treated with robotic-assisted radical prostatectomy for prostate cancer. The risk of ECE was calculated for each patient in several models (prostate side-specific and non-side-specific). Model performance was assessed by calculating the receiver operating curve and the area under the curve (AUC), calibration plots, and decision curve analyses. Results: We identified ECE in 117 (32.9%) of the 356 prostate lobes included. Patients with ECE had a statistically significant higher prostate-specific antigen level, percentage of positive digital rectal examination, percentage of hypoechoic nodes, percentage of magnetic resonance imaging nodes or ECE suggestion, percentage of biopsy positive cores, International Society of Urological Pathology grade group, and percentage of core involvement. Among the side-specific models, the Soeterik, Patel, Sayyid, Martini, and Steuber models presented AUC of 0.81, 0.78, 0.77, 0.75, and 0.73, respectively. Among the non-side-specific models, the memorial Sloan Kettering Cancer Center web calculator, the Roach formula, the Partin tables of 2016, 2013, and 2007 presented AUC of 0.74, 0.72, 0.64, 0.61, and 0.60, respectively. However, the 95% confidence interval for most of these models overlapped. The side-specific models presented adequate calibration. In the decision curve analyses, most models showed net benefit, but it overlapped among them. Conclusion: Models predicting ECE were externally validated in Japanese men. The side-specific models predicted better than the non-side-specific models. The Soeterik and Patel models were the most accurate performing models.

Androgen receptor mutations for precision medicine in prostate cancer.

Hormonal therapies including androgen deprivation therapy and androgen receptor (AR) pathway inhibitors such as abiraterone and enzalutamide have been widely used to treat advanced prostate cancer. However, treatment resistance emerges after hormonal manipulation in most prostate cancers, and it is attributable to a number of mechanisms, including AR amplification and overexpression, AR mutations, the expression of constitutively active AR variants, intra-tumor androgen synthesis, and promiscuous AR activation by other factors. Although various AR mutations have been reported in prostate cancer, specific AR mutations (L702H, W742L/C, H875Y, F877L, and T878A/S) were frequently identified after treatment resistance emerged. Intriguingly, these hot spot mutations were also revealed to change the binding affinity of ligands including steroids and antiandrogens and potentially result in altered responses to AR pathway inhibitors. Currently, precision medicine utilizing genetic and genomic data to choose suitable treatment for the patient is becoming to play an increasingly important role in clinical practice for prostate cancer management. Since clinical data between AR mutations and the efficacy of AR pathway inhibitors are accumulating, monitoring the AR mutation status is a promising approach for providing precision medicine in prostate cancer, which would be implemented through the development of clinically available testing modalities for AR mutations using liquid biopsy. However, there are few reviews on clinical significance of AR hot spot mutations in prostate cancer. Then, this review summarized the clinical landscape of AR mutations and discussed their potential implication for clinical utilization.