Prostate cancer is the most common malignant disease in men. Several therapeutic agents have been approved during the last 10 years. Among them, radium-223 dichloride (Xofigo^®) is a radioactive isotope that induces irreversible DNA double-strand breaks and consequently tumor cell death. Radium-223 dichloride is a calcium-mimetic agent that specifically targets bone lesions. Radium-223 dichloride has been approved for the treatment of metastatic castration-resistant prostate cancer with symptomatic bone metastases, without known visceral metastases. In this review, first we summarize the interplay between prostate tumor cells and bone microenvironment; then, we discuss radium-223 dichloride mechanism of action and present the results of the available clinical trials and future developments for this new drug.

Standard treatment of high-risk non-muscle-invasive bladder cancer (NMIBC) after transurethral resection of bladder tumor is intravesical instillation with Bacillus Calmette-Guérin (BCG) (induction and maintenance regimens); however, BCG therapy still fails in 30%-40% of patients. Prior studies suggest that programmed death-ligand 1 (PD-L1) expression and alterations in immune infiltration might be associated with BCG failure. The ALBAN trial is an international, 1 : 1 randomized, open-label phase III trial comparing the combination of atezolizumab (an anti-PD-L1 antibody) and BCG (arm B) versus BCG alone (arm A) for BCG-naive patients with high-risk NMIBC. The primary endpoint was investigator-assessed event-free survival (EFS). Key secondary endpoints included high-grade recurrence-free survival, complete response rate, and duration of response in patients with carcinoma in situ disease, as well as overall survival. In total, 255 patients were randomly assigned to arm A and 262 to arm B. The trial did not meet its primary endpoint; there was no significant difference in EFS between arms, with a hazard ratio of 0.98 (95% confidence interval 0.71-1.36, P = 0.9106). EFS results were consistent across all prespecified subgroups. The safety profile of the treatment combination was consistent with that of the individual agents but showed higher rates of treatment-related adverse events (TRAEs) and grade ≥3 TRAEs than BCG alone. This phase III trial in BCG-naive patients with high-risk NMIBC did not demonstrate an EFS benefit from the addition of atezolizumab to 1-year BCG therapy, in contrast to positive EFS results reported with another PD-(L)1 agent, suggesting that any benefit from checkpoint-BCG therapy may be context- and agent-specific rather than a class effect. Future research should focus on biomarker-driven patient selection and optimization of the timing, duration, and route of checkpoint delivery relative to BCG.

Background.: Preclinical studies demonstrated that non-nucleoside reverse transcriptase inhibitors used for the treatment of HIV could antagonize tumor development. This led us to assess the efficacy of efavirenz in patients with metastatic castration-resistant prostate cancer (mCRPC) in a multicenter phase II study. Methods.: We used a Simon two-stage design and a 3-month prostate-specific antigen (PSA) nonprogression rate of 40% as a primary objective. Patients received 600 mg efavirenz daily with the possibility of a dose increase in case of PSA progression. Exploratory analyses included pharmacokinetics of efavirenz plasma concentrations and correlations with clinical outcomes. Results.: Among 53 assessable patients, we observed 15 instances of PSA nonprogression at 3 months, corresponding to a nonprogression rate of 28.3% (95% confidence interval: 16.8%–42.3%). The exploratory analysis revealed that for the 7 patients in whom optimal plasma concentration of efavirenz was achieved, PSA progression was observed in only 28.6% compared with 81.8% of patients with suboptimal plasma concentrations of efavirenz. Conclusion.: Although 600 mg efavirenz did not statistically improve the PSA nonprogression rate, our exploratory analysis suggests that higher plasma concentrations of this drug (i.e., use of increased dosages) may be of potential benefit for the treatment of mCRPC.

In clinical trials, the use of intermediate time-to-event end points (TEEs) is increasingly common, yet their choice and definitions are not standardized. This limits the usefulness for comparing treatment effects between studies. The aim of the DATECAN Kidney project is to clarify and recommend definitions of TEE in renal cell cancer (RCC) through a formal consensus method for end point definitions. A formal modified Delphi method was used for establishing consensus. From a 2006–2009 literature review, the Steering Committee (SC) selected 9 TEE and 15 events in the nonmetastatic (NM) and metastatic/advanced (MA) RCC disease settings. Events were scored on the range of 1 (totally disagree to include) to 9 (totally agree to include) in the definition of each end point. Rating Committee (RC) experts were contacted for the scoring rounds. From these results, final recommendations were established for selecting pertinent end points and the associated events. Thirty-four experts scored 121 events for 9 end points. Consensus was reached for 31%, 43% and 85% events during the first, second and third rounds, respectively. The expert recommend the use of three and two endpoints in NM and MA setting, respectively. In the NM setting: disease-free survival (contralateral RCC, appearance of metastases, local or regional recurrence, death from RCC or protocol treatment), metastasis-free survival (appearance of metastases, regional recurrence, death from RCC); and local–regional-free survival (local or regional recurrence, death from RCC). In the MA setting: kidney cancer-specific survival (death from RCC or protocol treatment) and progression-free survival (death from RCC, local, regional, or metastatic progression). The consensus method revealed that intermediate end points have not been well defined, because all of the selected end points had at least one event definition for which no consensus was obtained. These clarified definitions of TEE should become standard practice in all RCC clinical trials, thus facilitating reporting and increasing precision in between trial comparisons.