Search

Before biomarkers can be used in clinical trials or patients' management, the laboratory assays that measure their levels have to go through development and analytical validation. One of the most critical performance metrics for validation of any assay is related to the minimum amount of values that can be detected and any value below this limit is referred to as below the limit of detection (LOD). Most of the existing approaches that model such biomarkers, restricted by LOD, are parametric in nature. These parametric models, however, heavily depend on the distributional assumptions, and can result in loss of precision under the model or the distributional misspecifications. Using an example from a prostate cancer clinical trial, we show how a critical relationship between serum androgen biomarker and a prognostic factor of overall survival is completely missed by the widely used parametric Tobit model. Motivated by this example, we implement a semiparametric approach, through a pseudo‐value technique, that effectively captures the important relationship between the LOD restricted serum androgen and the prognostic factor. Our simulations show that the pseudo‐value based semiparametric model outperforms a commonly used parametric model for modeling below LOD biomarkers by having lower mean square errors of estimation. [ABSTRACT FROM AUTHOR]

Background: Retrospective analyses of randomized trials suggest that Black men with metastatic castration‐resistant prostate cancer (mCRPC) have longer survival than White men. The authors conducted a prospective study of abiraterone acetate plus prednisone to explore outcomes by race. Methods: This race‐stratified, multicenter study estimated radiographic progression‐free survival (rPFS) in Black and White men with mCRPC. Secondary end points included prostate‐specific antigen (PSA) kinetics, overall survival (OS), and safety. Exploratory analysis included genome‐wide genotyping to identify single nucleotide polymorphisms associated with progression in a model incorporating genetic ancestry. One hundred patients self‐identified as White (n = 50) or Black (n = 50) were enrolled. Eligibility criteria were modified to facilitate the enrollment of individual Black patients. Results: The median rPFS for Black and White patients was 16.6 and 16.8 months, respectively; their times to PSA progression (TTP) were 16.6 and 11.5 months, respectively; and their OS was 35.9 and 35.7 months, respectively. Estimated rates of PSA decline by ≥50% in Black and White patients were 74% and 66%, respectively; and PSA declines to <0.2 ng/mL were 26% and 10%, respectively. Rates of grade 3 and 4 hypertension, hypokalemia, and hyperglycemia were higher in Black men. Conclusions: Multicenter prospective studies by race are feasible in men with mCRPC but require less restrictive eligibility. Despite higher comorbidity rates, Black patients demonstrated rPFS and OS similar to those of White patients and trended toward greater TTP and PSA declines, consistent with retrospective reports. Importantly, Black men may have higher side‐effect rates than White men. This exploratory genome‐wide analysis of TTP identified a possible candidate marker of ancestry‐dependent treatment outcomes. This is the first prospective, race‐stratified study in advanced prostate cancer demonstrating important trends in outcomes previously only observed in retrospective reports. These results demonstrate the feasibility of this approach in a multicenter setting and establish important preliminary data with regard to differences in toxicity profiles and predictive biomarkers by race. [ABSTRACT FROM AUTHOR]

BACKGROUND: The treatment for prostate cancer patients with biochemical failure after local therapy remains controversial. Peripheral androgen blockade using a combination of a 5-alpha reductase inhibitor and an antiandrogen may allow control of the prostate-specific antigen (PSA). Because testosterone levels are not suppressed, this approach may be associated with less morbidity than conventional gonadal androgen suppression. METHODS: All patients had undergone previous definitive local therapy and had evidence of a rising PSA >1ng/mL, with no evidence of recurrent disease. Patients received both finasteride, 5 mg orally per day, and flutamide, 250 mg orally 3× a day. Patients were followed for a PSA response and quality of life assessment. RESULTS: Ninety-nine of 101 accrued patients were eligible. A ≥80% PSA decline was seen in 96 (96%) patients. The median time to PSA progression was 85 months. With a median follow-up of 10 years, the median survival time had not been reached, and the 5-year overall survival rate was 87%. Toxicity was mild, with 18 patients stopping for toxicity; 15 had diarrhea, 4 had gynecomastia, and 3 had transaminase elevation. Baseline Functional Assessment of Cancer Therapy Prostate Module and Treatment Outcome Index scores decreased by 5 points each at 6 months after enrollment. CONCLUSIONS: The use of the finasteride/flutamide combination is feasible, and results in PSA declines of ≥80% in 96% of patients with serologic progression after definitive local therapy. There were no unexpected toxicities, and the change in quality of life was mild. Further evaluation of this or a similar regimen in a controlled clinical trial is warranted. Cancer 2012. © 2011 American Cancer Society. [ABSTRACT FROM AUTHOR]

BACKGROUND: The use of docetaxel prolongs survival for patients with castrate-resistant prostate cancer (CRPC). Inhibition of vascular endothelial growth factor (VEGF) with bevacizumab may further enhance the antitumor effect of docetaxel and estramustine in patients with CRPC. METHODS: This cooperative group trial enrolled men with CRPC. Patients received oral estramustine 280 mg 3 times daily on Days 1 through 5 of every cycle plus 70 mg/m² docetaxel and 15 mg/kg bevacizumab on Day 2 every 3 weeks. Prostate-specific antigen (PSA) values were monitored every cycle, and imaging studies were obtained every 3 cycles. The primary endpoint was progression-free survival (PFS), and the secondary objectives were safety, PSA decline, measurable disease response, and overall survival. RESULTS: Seventy-nine patients were enrolled; and 77 patients received a median of 8 cycles and were evaluable. A 50% PSA decline was observed in 58 patients (75%). Twenty-three of 39 patients with measurable disease had a partial response (59%). The median PFS was 8 months, and the overall median survival was 24 months. Neutropenia without fever (69%), fatigue (25%), and thrombosis/emboli (9%) were the most common severe toxicities. Twenty-four of 77 patients were removed from protocol treatment because of disease progression, 35 of 77 patients were removed because of a physician or patient decision, and 15 patients were removed secondary to toxicity. CONCLUSIONS: The combination of docetaxel, estramustine, and bevacizumab was tolerable but complicated by toxicity. Although the endpoint of PFS did not meet the desired level, encouraging antitumor activity and overall survival were observed. Further phase 3 evaluation of the role of bevacizumab in CRPC is ongoing. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the safety and feasibility of radiotherapy after paclitaxel, estramustine phosphate and carboplatin (TEC) plus androgen therapy in previously treated prostate cancer patients. It mentions that patients with localized high-risk prostate cancer were treated with four cycles of paclitaxel in a period of 16 weeks. It affirms that the authors concluded that neoadjuvant chemohormonal therapy with TEC followed by high-dose radiation therapy is safe.

The article focuses on a study that aims to evaluate the correlation between an elevated body mass index (BMI) and clinical outcomes in patients with metastatic, castration-recurrent prostate cancer (CRPC). It cites the association between obesity and the risk of certain malignancies such as colon cancer and renal cell carcinoma. It concludes that patients with metastatic CRPC, obesity appears to have a protective effect against overall mortality and prostate cancer-specific mortality.