Radium-223 plus Enzalutamide Versus Enzalutamide in Metastatic Castration-Refractory Prostate Cancer: Final Safety and Efficacy Results.

LESSONS LEARNED: Long-term safety of radium-223 with enzalutamide was confirmed in this clinical trial. PSA-PFS2 was prolonged with the combination compared with enzalutamide alone. BACKGROUND: Previously, we showed the combination of radium-223 and enzalutamide to be safe and associated with improved efficacy based on a concomitant decline in serum bone metabolism markers compared with enzalutamide alone in a phase II trial of men with metastatic castration-resistant prostate cancer (mCRPC) [1]. METHODS: Secondary endpoints were not included in our initial report, and we include them herein, after a median follow-up of 22 months. These objectives included long-term safety, prostate-specific antigen (PSA)-progression-free survival (PFS), and radiographic progression-free survival; PSA-PFS2 (time from start of protocol therapy to PSA progression on subsequent therapy); time to next therapy (TTNT); and overall survival (OS). Survival analysis and log-rank tests were performed using the R statistical package v.4.0.2 (https://www.r-project.org). Statistical significance was defined as p < .05. RESULTS: Of 47 patients (median age, 68 years), 35 received the combination and 12 enzalutamide alone. After a median follow-up of 22 months, final safety results did not show any increase in fractures or other adverse events in the combination arm. PSA-PFS2 was significantly improved, and other efficacy parameters were numerically improved in the combination over the enzalutamide arm. CONCLUSION: The combination of enzalutamide and radium-223 was found to be safe and associated with promising efficacy in men with mCRPC. These hypothesis-generating results portend well for the ongoing phase III PEACE III trial in this setting.

Systemic inflammatory biomarkers as predictive and prognostic factors in men with metastatic castration-refractory prostate cancer treated with docetaxel therapy: a comprehensive analysis in a German real-world cohort.

PURPOSE: Advances in therapy of metastatic castration-refractory prostate cancer (mCRPC) resulted in more therapeutic options and led to a higher need of predictive/prognostic biomarkers. Systemic inflammatory biomarkers could provide the basis for personalized treatment selection. This study aimed to assess the modified Glasgow Prognostic Score (mGPS), the neutrophile-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR) and the systemic immune-inflammation index (SII) in men with mCRPC under docetaxel. METHODS: Patients with mCRPC and taxane chemotherapy at a tertiary care centre between 2010 and 2019 were screened retrospectively. The biomarkers mGPS, NLR, PLR and SII were assessed and analyzed for biochemical/radiologic response and survival. RESULTS: We included 118 patients. Of these, 73 (61.9%) had received docetaxel as first-line, 31 (26.2%) as second-line and 14 (11.9%) as third-line treatment. For biochemical response, mGPS (odds ratio (OR) 0.54, p = 0.04) and PLR (OR 0.63, p = 0.04) were independent predictors in multivariable analysis. SII was significant in first-line cohort only (OR 0.29, p = 0.02). No inflammatory marker was predictive for radiologic response. In multivariable analysis, mGPS and NLR (hazard ratio (HR) 1.71 and 1.12, both p < 0.01) showed significant association with OS in total cohort and mGPS in the first-line cohort (HR 2.23, p < 0.01). Haemoglobin (Hb) and alkaline phosphatase (AP) showed several significant associations regarding 1 year, 3 year, OS and biochemical/radiologic response. CONCLUSIONS: Pre-treatment mGPS seems a promising prognostic biomarker. A combination of mGPS, NLR and further routine markers (e.g., Hb and AP) could yield optimized stratification for treatment selection. Further prospective and multicentric assessment is needed.

A Case Report of Metastatic Castration-Resistant Prostate Cancer Harboring a PTEN Loss.

The treatment landscape of metastatic castration-resistant prostate cancer (mCRPC) has dramatically improved over the last decade; however, patients with visceral metastases are still faced with poor outcomes. Phosphatase and tensin homolog (PTEN) loss is observed in 40%-60% of mCRPC patients and is also associated with a poor prognosis. Several PI3K/AKT/mTOR pathway inhibitors have been studied, with disappointing anti-tumor activity. Here, we present a case of a patient with heavily treated mCRPC who had a modest tumor response to concurrent carboplatin, abiraterone acetate/prednisone, and liver-directed radiation therapy. We discuss the potential rationale supporting the use of this combination therapy and its safety in mCRPC. While the underlying basic mechanism of our patient's anti-tumor response remains uncertain, we suggest that further prospective studies are warranted to evaluate whether this combination therapy is effective in this population of patients with pre-treated mCRPC and PTEN loss.

DNA Damage Repair (DDR) Mutations and the Utility of High-Risk Genetics Clinics in Metastatic Castration-Refractory Prostate Cancer (mCRPC).

Germline pathogenic variants (PVs) in DNA-repair genes have garnered increasing attention in metastatic prostate cancer, and more patients are having somatic and germline DNA testing performed. Interpretation of germline DNA testing is a novel challenge for many clinicians, and the results of germline DNA-repair gene testing have significant implications for men with advanced prostate cancer and their children and siblings. Here, we report the case of a man with metastatic castration-refractory prostate cancer and a pathogenic, germline BRCA2 variant. We discuss the significance of his referral to a high-risk genetics clinic and the unique targeted therapy that he responded to.

Abiraterone acetate withdrawal syndrome: Speculations on the underlying mechanisms.

A 72-year-old man initially presented with lumbar and right chest pain, but was later found out to also have an elevated prostate-specific antigen (PSA) level at 2,000.0 ng/ml. Further evaluation disclosed metastatic prostate cancer involving the bones and lymph nodes. The patient was initially treated with combined androgen blockade (CAB) with leuprolide acetate and bicalutamide. After 6 months of CAB, the patient's PSA level began to rise from the nadir (85.1 ng/ml) to 113.3 ng/ml. Bicalutamide was withdrawn in anticipation of anti-androgen withdrawal syndrome and the PSA level declined temporally. However, it increased up to 517.0 ng/ml thereafter. Consequently, a year after CAB, abiraterone acetate (AA) was initiated at a standard dose of 1,000 mg daily in combination with 10 mg of prednisolone. PSA rapidly decreased to the nadir of 20.1 ng/ml thereafter. The PSA level remained stable until 2 years after AA administration. However, he decided to reduce the dose of AA to half of the standard dose (500 mg daily). Contrary to our expectations, the serum PSA level promptly decreased to a nadir of 8.1 ng/ml. Thereafter, the PSA level remained stable until 3 years and 9 months after AA administration. Subsequently, the patient stopped taking AA and prednisolone. However, to our surprise, the patient's serum PSA level decreased further to <1.0 ng/ml after AA discontinuation. His PSA remained <1.0 ng/ml without clinical or radiological progression for 1 year after AA withdrawal. Recently, it was reported that cessation of AA is associated with AA withdrawal syndrome in metastatic castration-resistant prostate cancer, defined as a PSA decrease after AA discontinuation, mimicking anti-androgen withdrawal syndrome. In the present study, explanations of the mechanisms underlying this phenomenon were explored, including mutant AR activation by alternative ligands.