Celestia S. Higano

Multimarker Circulating DNA Assay for Assessing Blood of Prostate Cancer Patients

BACKGROUND Prostate cancer (PCa) detection using serum-based prostate specific antigen (PSA) is limited by frequent false-positive and -negative results. Genetic aberrations such as allelic imbalance (AI) and epigenetic changes such as promoter hypermethylation have been detected in circulating DNA of cancer patients. We hypothesized that circulating multimarker DNA assays detecting both genetic and epigenetic markers in serum would be useful in assessing PCa patients. METHODS We assayed blood from healthy male donors (n = 40) and 83 patients with American Joint Cancer Committee (AJCC) stage I-IV PCa. DNA was assayed for AI of 6 genome microsatellites. We assessed methylation of RASSF1, RARB2, and GSTP1 using a methylation-specific PCR assay and analyzed the sensitivity of each assay for the detection of genetic or epigenetic changes in circulating DNA. The relation between circulating tumor-related DNA detection and prognostic factors was investigated. RESULTS The proportion of patients demonstrating AI for > or =1 marker was 47% (38 of 81 patients). Methylation biomarkers were detected in 24 of 83 patients (28%). By combining 2 DNA assays, the number of PCa patients positive for > or =1 methylated or LOH marker increased (52 of 83; 63%). The combined assays detected PCa in 15 of 24 patients (63%) with normal PSA concentrations. The combination of the DNA assays detected the presence of PCa regardless of AJCC stage or PSA concentration. Combination of the DNA and PSA assays gave 89% sensitivity. CONCLUSIONS This pilot study demonstrates that the combined circulating DNA multimarker assay identifies patients with PCa and may yield information independent of AJCC stage or PSA concentration.

Phase III, randomized, placebo-controlled study of once-daily oral zibotentan (ZD4054) in patients with non-metastatic castration-resistant prostate cancer

Background:Standard treatment options are limited for the management of non-metastatic castration-resistant prostate cancer (CRPC). This study, part of the ENTHUSE (EndoTHelin A USE) phase III programme, evaluated the efficacy and safety of the oral specific endothelin (ET)A receptor antagonist zibotentan vs placebo in patients with non-metastatic CRPC (non-mCRPC).Methods:This was a multicentre, randomized, double-blind, phase III study. Patients (n=1421) with non-mCRPC and biochemical progression (determined by rising serum PSA levels) were randomized to receive zibotentan 10 mg or placebo once daily. Based on the lack of efficacy signal in another ENTHUSE phase III study, an interim analysis was performed to determine whether the study was likely to achieve the co-primary objectives of improved overall survival (OS) and progression-free survival (PFS).Results:Criteria for continuation of this study were not met. A total of 79 deaths and 293 progression events were recorded at final data cutoff. Zibotentan-treated patients did not significantly differ from placebo-treated patients for OS (hazard ratio (HR): 1.13; 95% confidence interval (CI): 0.73–1.76, P=0.589) or PFS (HR: 0.89; 95% CI: 0.71–1.12, P=0.330). The most commonly reported adverse events in zibotentan-treated patients were peripheral oedema (37.7%), headache (26.2%) and nasal congestion (24.9%); each occurred with >15% higher incidence than in the placebo group.Conclusions:This trial was terminated early because of failure at interim analysis of the efficacy data to meet the defined criteria for continuation. Owing to the absence of demonstrable survival benefits in the ENTHUSE clinical studies, zibotentan is no longer under investigation as a potential treatment for prostate cancer.

Radiographic progression with nonrising PSA in metastatic castration-resistant prostate cancer: post hoc analysis of PREVAIL

Background:Advanced prostate cancer is a phenotypically diverse disease that evolves through multiple clinical courses. PSA level is the most widely used parameter for disease monitoring, but it has well-recognized limitations. Unlike in clinical trials, in practice, clinicians may rely on PSA monitoring alone to determine disease status on therapy. This approach has not been adequately tested.Methods:Chemotherapy-naive asymptomatic or mildly symptomatic men (n=872) with metastatic castration-resistant prostate cancer (mCRPC) who were treated with the androgen receptor inhibitor enzalutamide in the PREVAIL study were analyzed post hoc for rising versus nonrising PSA (empirically defined as >1.05 vs ⩽1.05 times the PSA level from 3 months earlier) at the time of radiographic progression. Clinical characteristics and disease outcomes were compared between the rising and nonrising PSA groups.Results:Of 265 PREVAIL patients with radiographic progression and evaluable PSA levels on the enzalutamide arm, nearly one-quarter had a nonrising PSA. Median progression-free survival in this cohort was 8.3 months versus 11.1 months in the rising PSA cohort (hazard ratio 1.68; 95% confidence interval 1.26–2.23); overall survival was similar between the two groups, although less than half of patients in either group were still at risk at 24 months. Baseline clinical characteristics of the two groups were similar.Conclusions:Non-rising PSA at radiographic progression is a common phenomenon in mCRPC patients treated with enzalutamide. As restaging in advanced prostate cancer patients is often guided by increases in PSA levels, our results demonstrate that disease progression on enzalutamide can occur without rising PSA levels. Therefore, a disease monitoring strategy that includes imaging not entirely reliant on serial serum PSA measurement may more accurately identify disease progression.

Validation of the Association of RECIST Changes With Survival in Men With Metastatic Castration-Resistant Prostate Cancer Treated on SWOG Study S0421

Micro‐Abstract The association of Response Evaluation Criteria in Solid Tumors (RECIST) 1.0 changes within 120 days with survival in men with metastatic castration‐resistant prostate cancer receiving docetaxel was validated from a phase 3 trial. Given the limitations of prostate‐specific antigen and bone scan alterations to translate to improved survival, improved RECIST changes in phase 2 trials may be important before launching phase 3 trials. Background: Phase 2 trials evaluating new agents for metastatic castration‐resistant prostate cancer (mCRPC) have relied on bone scan and prostate‐specific antigen changes to assess activity. Given the increasing detection of measurable disease, Response Evaluation Criteria in Solid Tumors (RECIST) changes warrant consideration to evaluate activity. We validated the association of RECIST 1.0 changes with survival in men with mCRPC receiving docetaxel. Patients and Methods: Data for men with measurable disease from the Southwest Oncology Group (SWOG) S0421, a phase 3 trial in men with mCRPC receiving docetaxel and prednisone plus placebo or atrasentan, were used. Cox proportional hazards regression was used to evaluate the association of RECIST 1.0 outcomes within 120 days, ie, unconfirmed partial response (uPR), stable disease, and progressive disease (PD), with overall survival (OS) from day 120, adjusted for prognostic factors. Results: Overall, 326 men were evaluable for landmark analysis, of whom 23 had PD, 230 stable disease, and 73 uPR. OS beyond day 120 was significantly different (P = .004) among these subgroups, with median (95% confidence interval) OS of 7.1 (3.5‐8.8), 13.4 (11.4‐15.6), and 16.3 (10.0‐19.6) months for those with PD, stable disease, and uPR, respectively. In a multivariable model, the hazard ratio (95% confidence interval) for patients with PD was 2.47 (1.42‐4.29) compared to patients with an uPR (P = .002). Conclusion: The association of RECIST 1.0 changes with OS in men with mCRPC receiving docetaxel was validated. Given limitations of bone scan and prostate‐specific antigen alterations, improvements in objective RECIST 1.0 changes should be reported in phase 2 trials before launching phase 3 trials.

Metastatic Castration-Sensitive Prostate Cancer: Optimizing Patient Selection and Treatment

The treatment landscape for metastatic castration-sensitive prostate cancer (mCSPC) has rapidly evolved over the past 5 years. Although androgen-deprivation therapy (ADT) is still the backbone of treatment, the addition of docetaxel or abiraterone acetate has improved outcomes for patients with mCSPC and become standard of care. With multiple treatment options available for patients with mCSPC, treatment selection to optimize patient outcomes has become increasingly difficult. Here, we review the clinical trials involving ADT plus docetaxel or abiraterone and provide clinicians with guidelines for treatment. Although surgery and/or radiation are standard of care for localized, intermediate- and high-risk prostate cancer, these treatments are not routinely used as part of initial treatment plans for patients with de novo mCSPC. Recent clinical data are challenging that dogma, and we review the literature on the addition of surgery and radiation to systemic therapy for mCSPC. Finally, the standard of care for oligometastatic prostate cancer (a subset of mCSPC with limited metastases) has not been established compared with that for some other cancers. We discuss the recent studies on metastasis-directed therapy for treatment of oligometastatic prostate cancer.