The Emerging Role of Local Therapy in Metastatic Prostate Cancer

Trends in the use of local intervention for metastatic hormone-naïve prostate cancer: A multicenter retrospective study

OBJECTIVE

To evaluated the trends of local intervention and their impact on oncological outcomes in metastatic hormone-naïve prostate cancer (mHNPC) in real-world practice.

METHODS

This retrospective multicenter study included 760 patients treated with either androgen deprivation therapy (ADT) without local treatment (no castration-resistant prostate cancer [CRPC] progression within 12 months, control group) or ADT plus local intervention (intervention group) between January 2005 and March 2022. We evaluated the trends in the use of local intervention in patients with mHNPC and factors associated with CRPC-free survival in the intervention group.

RESULTS

The use of local intervention gradually increased in combination with upfront combination treatment (docetaxel or androgen receptor axis-targeted agents) for the duration of our study. The number of patients with local intervention combined with upfront treatment was significantly higher in patients with high tumor burden disease than in those with low tumor burden disease. Of the 108 patients who received local intervention, a duration of ≤7 months of initial therapy before local intervention and a level of prostate-specific antigen ≥0.20 ng/mL at the time of local intervention were significantly associated with poor CRPC-free survival.

CONCLUSIONS

The use of local intervention in combination with upfront therapy to treat mHNPC increased for the duration of our study regardless of the tumor burden. Local intervention in addition to the standard of care for mHNPC may be a feasible treatment option for selected patients, taking into consideration the duration of and response to initial treatment.

Clinical Significance of Mesenchymal Circulating Tumor Cells in Patients With Oligometastatic Hormone-Sensitive Prostate Cancer Who Underwent Cytoreductive Radical Prostatectomy

Purpose

Growing evidence shows that circulating tumor cells (CTCs) become more aggressive after the epithelial–mesenchymal transition (EMT), though the clinical significance of CTCs undergoing EMT in oligometastatic hormone-sensitive prostate cancer (omHSPC) patients has not yet been reported. Accordingly, the aim of this study was to detect the CTC level and investigate the clinical significance of mesenchymal CTCs in omHSPC patients who underwent cytoreductive radical prostatectomy (CRP).

Materials and Methods

Blood samples were drawn from 54 omHSPC patients who underwent CRP. The CanPatrol CTC enrichment technique was applied to isolate and identify different phenotypes of CTCs, which were classified as epithelial (E-CTCs), mesenchymal (M-CTCs), or biphenotypic epithelial/mesenchymal (Bi-CTCs). Univariable and multivariable Cox regression analyses were employed to investigate potential prognostic factors for metastatic castration-resistant prostate cancer (mCRPC)-free survival and cancer-specific survival (CSS). The prognostic value of CTCs for CSS and mCRPC-free survival was assessed using time-dependent receiver operating characteristic (ROC) curves and Kaplan–Meier analysis.

Results

CTCs were detected in 51 of 54 patients (94%). E-CTC, M-CTC, and Bi-CTC detection rates were 56%, 67%, and 85%, respectively. A positive correlation was found between the M-CTC count and number of bone metastases (p = 0.012). Time-dependent ROC analysis showed that the M-CTC count had higher predictive power than E-CTC or Bi-CTC for mCRPC-free survival (3-year area under the curve [AUC] values: 0.64, 0.60, and 0.61) and CSS (3-year AUC: 0.86, 0.58, and 0.67). Additionally, time-dependent ROC analysis revealed total CTCs (T-CTCs) ≥5 and M-CTCs ≥2 to be the cutoff points with optimal specificity and sensitivity. Based on multivariable Cox regression, T-CTC and M-CTC counts were both independently associated with CSS and mCRPC-free survival (all p < 0.05), though E-CTCs and Bi-CTCs had no significant prognostic value (all p > 0.05). Patients with T-CTC ≥5 or M-CTC ≥2 had significantly worse mCRPC-free survival and CSS than those with T-CTC<5 or M-CTC<2 (all p < 0.05) after CRP.

Conclusion

CTC quantification and phenotype characterization provide prognostic information, and M-CTCs can be used as a novel biomarker for omHSPC patients who undergo CRP. The results need to be validated in prospective studies.

The treatment landscape of metastatic prostate cancer

The treatment landscape of metastatic prostate cancer has evolved significantly over the past two decades. Several landmark phase 3 trials led to new drug approvals and rapid changes in therapy options for patients, including drugs with distinct mechanisms of action (e.g., hormonal, chemotherapy, radionuclide, immunotherapy, and targeted therapies). Therapies initially developed in later stages of the disease (metastatic castration resistant prostate cancer) have started to move earlier in the prostate cancer continuum, with new standards of care for metastatic hormone naive prostate cancer and non-metastatic castration resistant prostate cancer. Overall, patients are living longer with a better quality of life. However, despite these significant advances, prostate cancer remains a leading cause of cancer death globally. Disease heterogeneity and the emergence of therapy resistance remain significant barriers, and the identification and application of molecular biomarkers to guide the choice and sequencing of systemic agents are still in early stages. Here we discuss the current treatment landscape of metastatic prostate cancer, clinical challenges, and the emerging role of molecular biomarkers for targeting biologic subsets of advanced disease and co-targeting heterogenous resistance patterns.

25-year perspective on prostate cancer: Conquering frontiers and understanding tumor biology

Major changes in the field of prostate cancer over the last 25 years include the implementation of prostate specific antigen screening and the recognition that BRCA confers hereditary risk of prostate cancer. Quality of life and survivorship have driven risk stratification for localized prostate cancer, facilitated by molecular signatures and leading to increased acceptance of active surveillance as a mainstream treatment option. Advances in technology have improved efficacy and reduced toxicity in both radical prostatectomy and radiation therapy for localized prostate cancer. Improved understanding of the androgen receptor has yielded substantially more effective therapies. Future growth areas include personalized treatment based on genomic and genetic information, theranostics radiopharmaceuticals, and more aggressive treatment of metastatic disease to include focal therapy. Multidisciplinary management between specialized urologists, radiation oncologists, and medical oncologists remains central to maximizing patient outcomes.

The Effect of Local Therapy on M1c Prostate Cancer Patients: A Systematic Review and Meta-Analysis

Background: A systematic review and meta-analysis was conducted to explore the effect of local treatment (LT) on overall survival (OS) and cancer-specific mortality (CSM) for patients diagnosed with M1c prostate cancer (PCa). Methods: PubMed, Web of Science, Embase, EBSCO, and Cochrane library databases (updated November 2020) were searched for studies assessing the effect of LT on patients with M1c Pca. The search strategy and study selection process was managed according to the PRISMA statement. Results: Four cohort respective studies were identified for satisfying the inclusion criteria. Our results indicated that LT significantly improved CSM (HR = 0.36, 95% CI = 0.22-0.60; P < 0.0001) and OS (HR = 0.42, 95% CI = 0.24-0.77; P = 0.004). Subgroup analysis showed that radical prostatectomy (RP) and radiation therapy (RT) including brachytherapy (BT), conformal radiation therapy (CRT), and intensity modulated radiation (IMRT) had a significant benefit on cutting down the CSM of M1c PCa patients (HR = 0.27, 95% CI = 0.13-0.56; P = 0.0005 and HR = 0.42, 95% CI = 0.20-0.89; P = 0.02). In addition, RP had improved the OS for patients (HR = 0.33, 95% CI = 0.15-0.73; P = 0.008). There was no difference of OS in patients that underwent RT (HR = 0.58, 95% CI = 0.24-1.40; P = 0.23). No significant heterogeneity was among the results, indicating consistency in the study. Conclusions: Present meta-analysis indicates that LT for M1c PCa correlated with decreased CSM and enhanced OS. The survival benefit of RP was successfully confirmed and the advantage of RT seemed to be associated with the tumor burden and method of RT.

Review of Radium-223 and Metastatic Castration-Sensitive Prostate Cancer

Background: Radium-223 is approved for treatment of bone metastases in metastatic castration-resistant prostate cancer (mCRPC). After the ALSYMPCA trial showed overall survival benefit with the addition of radium-223 to standard of care in mCRPC in 2013, there have been numerous publications and trials using radium-223 in mCRPC. Recently, there has been interest in using radium-223 earlier in the metastatic prostate cancer timeline, in metastatic castrate-sensitive prostate cancer (mCSPC); however, currently, radium-223 in mCSPC treatment is investigational. Aim: A literature search was conducted to review the use of radium-223 in mCSPC treatment from 1980 to 2019. A review of both radium-223 articles and abstracts was performed. Search terms included metastatic prostate cancer and radium-223, mCSPC, hormone-sensitive metastatic prostate cancer, radium-223, and oligometastatic disease. The results were limited to studies involving multiple patients with mCSPC. Conclusion: There are a limited number of studies of radium-223 in mCSPC treatment and the authors report on these studies (two published studies and four ongoing trials). Trials are currently underway to assess if radium-223 could be used in mCSPC as a treatment for bone metastases and micrometastases. Future data from these trials will be informative as to the benefit of radium-223 in mCSPC treatment and may change treatment paradigms for mCSPC. This review will focus on trials assessing the role of radium-223 in mCSPC.