Optimal Testosterone Control and Eligard®

Definition of Castrate Resistant Prostate Cancer: New Insights

The term castrate resistant prostate cancer (CRPC) was initially proposed by the Prostate Cancer Working Group 2 in 2008 to define the state of clinical and/or biochemical progression of prostate cancer (PCa) in an environment with very low serum testosterone concentration. Clinical progression is based on the radiological imaging proposed by the Response Evaluation Criteria in Solid Tumors (RECIST) adapted to PCa. Biochemical progression is defined as an over 25% increase in serum prostate-specific antigen within two consecutive measurements separated by at least one week, and an absolute value above 2.0 ng/mL. Finally, the castrate environment is usually defined as a serum testosterone concentration maintained below 50 ng/dL or 1.7 nmol/dL. This definition does not incorporate the new and more accurate imaging modalities to assess clinical progression and the capability of the new biochemical measurements to assess the true castration environment. Ga-68-PSMA-11 PET CT/MRI and whole-body MRI are the new imaging modalities that should replace the classic thoracic CT scan, abdomino-pelvic CT scan, and technetium 99-m bone scintigraphy. In addition, Ga-68-PSMA-11 PET is the current basis for the new therapies targeting metastatic sites. Moreover, the current methods for measuring the very low serum testosterone concentrations in clinical laboratories are the widespread chemiluminescent assays, which are inappropriate, while LC-MSMS is the only method recommended to assess the castrate environment. In addition, recent research shows that serum luteinising hormone concentration associates better than serum testosterone with the castration environment, even when it is measured with LC-MSMS. In summary, the current definition of CRPC seems outdated. An extensive update to diagnose true CRPC is also needed to differentiate CRPC men with M0 (non-metastatic) from those with M1 (metastatic) CRPC. WC: 277.

Stimuli-Responsive Nano-Architecture Drug-Delivery Systems to Solid Tumor Micromilieu: Past, Present, and Future Perspectives

The microenvironment characteristics of solid tumors, renowned as barriers that harshly impeded many drug-delivery approaches, were precisely studied, investigated, categorized, divided, and subdivided into a complex diverse of barriers. These categories were further studied with a particular perspective, which makes all barriers found in solid-tumor micromilieu turn into different types of stimuli, and were considered triggers that can increase and hasten drug-release targeting efficacy. This review gathers data concerning the nature of solid-tumor micromilieu. Past research focused on the treatment of such tumors, the recent efforts employed for engineering smart nanoarchitectures with the utilization of the specified stimuli categories, the possibility of combining more than one stimuli for much-greater targeting enhancement, examples of the approved nanoarchitectures that already translated clinically as well as the obstacles faced by the use of these nanostructures, and, finally, an overview of the possible future implementations of smart-chemical engineering for the design of more-efficient drug delivery and theranostic systems and for making nanosystems with a much-higher level of specificity and penetrability features.

Serum Testosterone Levels in Prostate Cancer Patients Undergoing Luteinizing Hormone-Releasing Hormone Agonist Therapy

BACKGROUND

Serum testosterone measurement is recommended to assess the efficacy of androgen deprivation therapy (ADT) and to diagnose castration resistance in patients with prostate cancer (PCa). Currently, the accepted castrate level of serum testosterone is 50 ng/dL. Liquid chromatography and tandem mass spectrometry (LC MSMS) is the appropriate method to measure testosterone, especially at low levels. However, worldwide, chemiluminescent assays (CLIAs) are used in clinical laboratories, despite their lack of accuracy and reproducibility, because they are automatable, fast, sensitive, and inexpensive.

MATERIALS AND METHODS

We compared serum testosterone levels measured using LC MSMS and CLIAs in 126 patients with PCa undergoing luteinizing hormone-releasing hormone (LHRH) agonist therapy.

RESULTS

The median serum testosterone level was 14.0 ng/dL (range, 2.0-67.0 ng/dL) with LC MSMS and 31.9 ng/dL (range, 10.0-91.6 ng/dL) with CLIA (P < .001). The serum testosterone levels, measured using LC MSMS, were < 20 ng/dL in 83 patients (65.9%), 20 to 50 ng/dL in 40 (31.7%), and > 50 ng/dL in 3 patients (2.4%). These ranges were found in 34 (27%), 72 (57.1%), and 20 (15.9%) patients when testosterone was measured using CLIA (P < .001). The castrate level of serum testosterone using LC MSMS and CLIA was 39.8 ng/dL (95% confidence interval [CI], 37.1-43.4 ng/dL) and 66.5 ng/dL (95% CI, 62.3-71.2 ng/dL), respectively.

CONCLUSION

We found that CLIA overestimated the testosterone levels in PCa patients undergoing LHRH agonist therapy. Thus, the castration level was incorrectly considered inadequate with CLIA in almost 15% of patients. The true castration level of serum testosterone using an appropriate method is < 50 ng/dL.

Clinical Outcomes and Testosterone Levels Following Continuous Androgen Deprivation in Patients with Relapsing or Locally Advanced Prostate Cancer: A Post Hoc Analysis of the ICELAND Study

PURPOSE

Lower serum testosterone levels correlate with improved cause specific survival and longer time to progression in year 1 of continuous androgen deprivation in men with prostate cancer. ICELAND was a large European study demonstrating the efficacy of leuprorelin (Eligard®) during continuous androgen deprivation. In this post hoc analysis we investigated serum testosterone levels within year 1 of continuous androgen deprivation to determine survival and time to progression.

MATERIALS AND METHODS

In ICELAND (ClinicalTrials.gov NCT00378690) patients with locally advanced or relapsing nonmetastatic prostate cancer and with prostate specific antigen 1 ng/ml or less following 6-month induction with leuprorelin 3-month depot 22.5 mg (plus bicalutamide 50 mg per day for 1 month) were randomized 1:1 to continuous androgen deprivation (361) or intermittent androgen deprivation (340) with leuprorelin for 36 months. Patients receiving continuous androgen deprivation were stratified by minimum, median and maximum testosterone levels during year 1 of therapy into 20 or less, greater than 20 to 50 and greater than 50 ng/dl subgroups. Cause specific survival and time to prostate specific antigen (castrate resistant prostate cancer) progression were analyzed.

RESULTS

A total of 90.1%, 83.5% and 74.5% of patients receiving continuous androgen deprivation achieved minimum, median and maximum serum testosterone levels of 20 ng/dl or less, respectively. Cause specific survival rates and time to prostate specific antigen progression did not differ among the testosterone subgroups.

CONCLUSIONS

In patients receiving continuous androgen deprivation cause specific survival and time to prostate specific antigen progression did not differ according to testosterone levels in year 1 of therapy. This finding may in part be due to the induction period and the effectiveness of leuprorelin in lowering testosterone.