Should We Try Antiandrogen Withdrawal in Castration-Resistant Prostate Cancer Patients? Insights From a Retrospective Study

Treatment strategy for metastatic prostate cancer with extremely high PSA level: reconsidering the value of vintage therapy

The prognostic significance of initial prostate-specific antigen (PSA) level for metastatic prostate cancer remains uncertain. We investigated the differences in prognosis and response to hormonal therapies of metastatic prostate cancer patients according to initial PSA levels. We analyzed 184 patients diagnosed with metastatic prostate cancer and divided them into three PSA level groups as follows: low (<100 ng ml⁻¹), intermediate (100–999 ng ml⁻¹), and high (≥1000 ng ml⁻¹). All patients received androgen deprivation therapy (ADT) immediately. We investigated PSA progression-free survival (PFS) for first-line ADT and overall survival (OS) within each of the three groups. Furthermore, we analyzed response to antiandrogen withdrawal (AW) and alternative antiandrogen (AA) therapies after development of castration-resistant prostate cancer (CRPC). No significant differences in OS were observed among the three groups (P = 0.654). Patients with high PSA levels had significantly short PFS for first-line ADT (P = 0.037). Conversely, patients in the high PSA level group had significantly longer PFS when treated with AW than those in the low PSA level group (P = 0.047). Furthermore, patients with high PSA levels had significantly longer PFS when provided with AA therapy (P = 0.049). PSA responders to AW and AA therapies had significantly longer survival after CRPC development than nonresponders (P = 0.011 and P < 0.001, respectively). Thus, extremely high PSA level predicted favorable response to vintage sequential ADT and AW. The current data suggest a novel aspect of extremely high PSA value as a favorable prognostic marker after development of CRPC.

Androgen deprivation therapy for the treatment of prostate cancer: a focus on pharmacokinetics

INTRODUCTION

Medical therapy has undergone many changes as our understanding of prostate cancer cell biology has improved. Androgen deprivation therapy (ADT) remains the mainstay of therapy for metastatic disease. Metastatic castrate-resistant prostate cancer (CRPC) is an important concern since we are unable to stop progression with currently available agents. Areas covered: Pharmacologic ADT is the most commonly used treatment for metastatic prostate cancer. Multiple agents are available for both first-line and second-line use: antiandrogens, estrogens, luteinizing hormone-releasing hormone agonists/antagonists, and CYP17 inhibitors. With adoption of these drugs, it is important to consider their pharmacokinetic and pharmacodynamic properties. Many undergo metabolism through cytochrome P450. Levels may be altered with co-administration of drugs acting as enzyme inhibitors or inducers. Understanding mechanism of action, metabolism, and excretion of these drugs allows clinicians to provide the best therapeutic care while minimizing adverse events. Expert opinion: Many men with metastatic prostate cancer will progress to castration resistance. An understanding of resistance mechanisms at the cellular level has revealed new drug targets with hopes of halting or reversing progression of metastatic disease. Second-line agents, traditionally reserved for CRPC, are being studied in metastatic castrate-sensitive prostate cancer, and may offer practice-changing evidence supporting their use.