Dose-dependent effect of androgen deprivation therapy for localized prostate cancer on adverse cardiac events

Androgen Deprivation Therapy/Androgen Receptor Signaling Inhibitor Treatments for Prostate Cancer: Pathophysiology and Review of Effects on Cardiovascular Disease

Androgen deprivation therapy is the cornerstone of systemic management for prostate cancer but is associated with multiple adverse effects that must be considered during treatment. These effects occur because of the profound hypogonadism that is induced from lack of testosterone or due to the medications used in the treatment or in combination with androgen receptor signaling inhibitors. This article critically reviews the associations between androgen deprivation therapy, androgen receptor signaling inhibitors, and cardiovascular complications such as prolonged QT interval, atrial fibrillation, heart failure, atherosclerosis, coronary heart disease, venous thromboembolism, and peripheral arterial occlusive disease. These unfavorable outcomes reinforce the need for regular cardiovascular screening of patients undergoing androgen deprivation for the management of prostate cancer.

Optimizing anti-androgen treatment use among men with pathologic lymph-node positive prostate cancer treated with radical prostatectomy: the importance of postoperative PSA kinetics

BACKGROUND

Optimal postsurgical management of prostate cancer (PCa) patients with nodal metastasis at the time of radical prostatectomy remains unclear. We sought to examine the role of postoperative PSA kinetics and pathologic tumor characteristics in guiding additional hormonal therapy use in pN1 men.

METHODS

In total, 297 pN1 PCa patients treated with radical prostatectomy and ePLND between 2002 and 2018 were identified within our prospectively maintained institutional cancer data-registry. Following surgery, these patients were managed with either immediate androgen deprivation therapy (iADT) or observation with deferred ADT (dADT). The former was defined as ADT given within ≤6 months of surgery and the latter as >6 months. The primary outcome was metastasis. Regression-tree analysis was used to stratify patients into novel risk-groups based on post-prostatectomy tumor characteristics and PSA kinetics and the corresponding metastasis risk. Multivariable Cox regression analyses tested the impact of iADT versus observation ± dADT on metastasis, cancer-specific mortality, and overall mortality within each risk-group separately.

RESULTS

The median follow-up was 6.1 years (IQR 3.2-9.0). Regression-tree analysis stratified patients into 3 novel risk-groups (Harrell's C-index 0.79) based on PSA-nadir and time to biochemical failure: group 1 (low-risk) included patients with time to biochemical recurrence >6 months (n = 115), while groups 2 and 3 included patients with biochemical failure within ≤6 months with a postoperative PSA-nadir <1.05 ng/mL (group 2 [intermediate-risk], n = 125) or ≥1.05 ng/mL (group 3 [high-risk], n = 57), respectively. No other patient or tumor characteristics were significant for risk stratification. Within each risk-group, the 10-year metastasis-free survival rates with iADT versus observation ± dADT use were: group 1, 100% versus 95.4% (Log-rank p = 0.738), group 2, 80.6% versus 53.5% (Log-rank p = 0.016), and group 3, 41.5% versus 0% (Log-rank p = 0.015), respectively. Adjusted Cox regression analyses confirmed the benefit of iADT utilization in reducing metastasis in group 2 (p = 0.029) and group 3 (p = 0.008) patients, with no benefit for group 1 patients (p = 0.918). Similar results were noted for cancer-specific and overall mortality.

CONCLUSIONS

Following radical prostatectomy, early postoperative PSA kinetics may provide valuable information for guiding the timing of ADT initiation-this may reduce over- and undertreatment of pN1 PCa men.

Association between medical androgen deprivation therapy and long-term cardiovascular disease and all-cause mortality in non-metastatic prostate cancer

Studies have suggested that prostate cancer (PCa) patients receiving androgen deprivation therapy (ADT) are at increased risk of developing or exacerbating cardiovascular disease (CVD). We aimed to explore the association between ADT for PCa and subsequent CVD and all‐cause mortality in this nationwide, longitudinal study. We also evaluated the role of cardiovascular risk and ADT duration to determine effect modification. Norwegian registry data were used to identify patients with PCa from 2008‐18 and who received primary ADT in the first year after diagnosis. The associations between ADT and composite cardiovascular events, and the individual components of myocardial infarction, stroke and heart failure, in addition to atrial fibrillation and all‐cause mortality, were explored using time‐varying Cox regression models. We included 30 923 PCa patients, of whom 8449 (27%) received primary ADT. Mean follow‐up was 2.9 and 3.8 years for CVD events and mortality, respectively. We found an association between ADT and composite CVD (adjusted HR 1.13: 95% CI 1.05‐1.21), myocardial infarction (1.18: 1.05‐1.32), stroke (1.21: 1.06‐1.38), heart failure (1.23: 1.13‐1.35) and all‐cause mortality (1.49: 1.39‐1.61). These associations persisted in those with low and moderate CVD risk and ADT longer than 7 months. A relationship between ADT and composite CVD and all‐cause mortality was observed, especially in those with moderate CVD risk and longer treatment duration. Future studies with more detailed cancer data are needed to verify the clinical relevance of these results, especially when considering all‐cause mortality within the context of treatment guidelines and benefits of ADT.

Chest Pain: Common Side Effect

For chest pain, standards of care are based on emerging evidence-based practice.&nbsp;Angina (chest pain) is the feeling of pressure, fullness, burning, squeezing, or tightness in the chest, usually provoked by exertion and relieved by rest. The discomfort can occur in the shoulders, arms, neck, jaw, or back, and radiates to one or both arms.&nbsp;Women who experience acute myocardial infarction often present with atypical chest pain and other symptoms, such as dyspnea, weakness, and fatigue.

NCCN Guidelines Insights: Survivorship, Version 2.2020

The NCCN Guidelines for Survivorship provide screening, evaluation, and treatment recommendations for consequences of adult-onset cancer and its treatment, with the goal of helping healthcare professionals who work with survivors, including those in primary care. The guidelines also provide recommendations to help clinicians promote physical activity, weight management, and proper immunizations in survivors and facilitate care coordination to ensure that all of the survivors' needs are addressed. These NCCN Guidelines Insights summarize additions and changes made to the guidelines in 2020 regarding cardiovascular disease risk assessment and screening for subsequent primary malignancies.

Survivorship, Version 2.2018, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Survivorship provide screening, evaluation, and treatment recommendations for common physical and psychosocial consequences of cancer and cancer treatment to help healthcare professionals who work with survivors of adult-onset cancer in the posttreatment period. This portion of the guidelines describes recommendations regarding the management of anthracycline-induced cardiotoxicity and lymphedema. In addition, recommendations regarding immunizations and the prevention of infections in cancer survivors are included.

Risk of Dementia and Depression in Young and Middle-aged Men Presenting with Nonmetastatic Prostate Cancer Treated with Androgen Deprivation Therapy

BACKGROUND

Previous studies have found an association between androgen deprivation therapy (ADT) and an increased risk of dementia and depression in elderly men. This association remains controversial, and little is known about the effects of ADT in younger men.

OBJECTIVE

To examine the association between the receipt of ADT and these outcomes in young men aged 40-64 yr presenting with nonmetastatic prostate cancer (PCa).

DESIGN, SETTING, AND PARTICIPANTS

For this observational study, we identified 9117 men aged 40-64 yr diagnosed with localized PCa between 2007 and 2014, without a pre-existing neurocognitive diagnosis, using the TRICARE military database.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Kaplan-Meier curves were fitted to compare ADT versus no ADT. We also performed a subgroup analysis in patients undergoing ADT for ≥12 mo. The association between ADT and new-onset dementia or depression was evaluated using inverse-probability-of treatment-weight-adjusted Cox proportional hazards regression analysis.

RESULTS AND LIMITATIONS

Patients receiving ADT had a significantly higher incidence of depression (30.2 vs 15.8 per 1000 person years) and dementia (17.9 vs 7.5 per 1000 person years). The risk of developing either outcome was higher in the ADT cohort (depression: hazard ratio [HR] 2.07, p < 0.001; dementia: HR 1.70, p = 0.052). Additionally, there was a dose-response relationship between the duration of ADT and either outcome.

CONCLUSIONS

In our cohort of young men with PCa, the receipt of ADT was associated with an increased risk of developing dementia and depression. Long-term use of ADT was associated with the highest risk of neurocognitive outcomes.

PATIENT SUMMARY

In this study, we looked at the risk of dementia and depression in patients <65 yr of age undergoing androgen deprivation therapy (ADT) for prostate cancer. We found that these patients had a higher risk of dementia and depression than those who did not undergo ADT.

Association Between Androgen Deprivation Therapy Use and Diagnosis of Dementia in Men With Prostate Cancer

Importance

The association between androgen deprivation therapy (ADT) exposure and dementia is uncertain.

Objective

To analyze the association between ADT exposure and diagnosis of Alzheimer disease or dementia among elderly men with prostate cancer.

Design, Setting, and Participants

This retrospective cohort study used data from the National Cancer Institute's Surveillance, Epidemiology, and End Results-Medicare linked database. Participants were 154 089 elderly men newly diagnosed with prostate cancer between 1996 and 2003. The analyses were conducted between November 1, 2018, and December 31, 2018.

Exposure

Androgen deprivation therapy.

Main Outcomes and Measures

Patients receiving ADT within 2 years of prostate cancer diagnosis were identified. Survival analysis was used to determine the association between ADT exposure and diagnosis of Alzheimer disease or dementia in the follow-up period. Propensity score and instrumental variable approaches were used to minimize measured and unmeasured selection bias. The association by dose of ADT was also examined.

Results

Of the 295 733 men diagnosed with prostate cancer between 1996 and 2003, 154 089 met the study criteria. Of these, 62 330 (mean [SD] age, 76.0 [6.0] years) received ADT within 2 years of prostate cancer diagnosis, and 91 759 (mean [SD] age, 74.3 [6.0] years) did not receive ADT. Mean (SD) follow-up was 8.3 (4.7) years. Exposure to ADT, compared with no ADT exposure, was associated with a diagnosis of Alzheimer disease (13.1% vs 9.4%; difference, 3.7%; 95% CI, 3.3%-3.9%; P < .001; hazard ratio [HR], 1.14; 95% CI, 1.10-1.18) and dementia (21.6% vs 15.8%; difference, 5.8%; 95% CI, 5.4%-6.2%; P < .001; HR, 1.20; 95% CI, 1.17-1.24). For 1 to 4 doses of ADT, the HR was 1.19 (95% CI, 1.15-1.24) for Alzheimer disease and 1.19 (95% CI, 1.15-1.23) for dementia. For 5 to 8 doses of ADT, the HR was 1.28 (95% CI, 1.22-1.35) for Alzheimer disease and 1.24 (95% CI, 1.19-1.29) for dementia. For more than 8 doses of ADT, the HR was 1.24 (95% CI, 1.16-1.34) for Alzheimer disease and 1.21 (95% CI, 1.15-1.28) for dementia. The number needed to harm was 18 patients (95% CI, 17-19 patients) and 10 patients (95% CI, 9.5-11 patients) for Alzheimer disease and dementia, respectively.

Conclusions and Relevance

Among elderly patients with prostate cancer, ADT exposure was associated with subsequent diagnosis of Alzheimer disease or dementia over a follow-up period of at least 10 years.

Adjuvant androgen deprivation therapy for prostate cancer treated with radiation therapy

Radiation therapy is a commonly used curative modality for prostate cancer. The addition of androgen deprivation therapy (ADT) increases the curative potential of prostate radiotherapy (RT) in multiple subsets of patients. In addition to having an independent cytotoxic effect, current evidence suggests that androgen deprivation synergistically works with radiation therapy by preventing DNA repair. Given the wide-ranging toxicities of this therapy, clinicians must judiciously choose which patients may benefit from ADT and also consider the appropriate length of treatment. With recent advances in RT delivery, higher doses of radiation are currently used when compared with the dose used in historic trials, leading to the unanswered question of how RT dose interacts with ADT. Current and future clinical studies are attempting to further define the appropriate indications and patient populations for which ADT represents a clinically appropriate addition to prostate RT.

Extrafascial robot-assisted laparoscopic radical prostatectomy in locally advanced prostate cancer

INTRODUCTION

Up to 26.5% of new diagnosed prostate cancers (PCa) are locally advanced (LA). Although traditionally discouraged in this setting, radical prostatectomy (RP) lowers the risk of metastatic progression and cancer-specific death. We report a review of the available evidences and describe our surgical technique of extrafascial robot-assisted RP.

EVIDENCE ACQUISITION

The PubMed/Medline database was searched for "prostate cancer," "high-risk," "locally advanced," "prostatectomy." Duplicates and expert opinion papers were removed.

EVIDENCE SYNTHESIS

RP is an option in selected patients with LA-PCa and >10 years life expectancy. Five, 10 and 15 years after open RP, disease free survival rates were 85%, 73% and 67%. At the same time-points, cancer specific survival and overall survival were 95%, 90%, 79% and 90%, 76%, 53%, respectively. Postoperative potency was achieved by 25% of the patients while 79% were continent. Robotic prostatectomy provides comparable cancer control outcomes, but it is associated with a lower transfusion rate and a shorter hospitalization time. The concept of "extrafascial prostatectomy" was introduced in 2000 by Villers: this surgical approach reduces the incidence of mid- and postero-lateral positive margins (28% vs. 51%, when compared to intrafascial; P=0.08), expecially in pT3 cancers, but markedly affects potency.

CONCLUSIONS

Robot-assisted RP is an option in patients with LA-PCa. Removing the prostate gland and the seminal vesicles still contained inside their aponeurotic covering, minimize the risk of positive surgical margins and clinical recurrence.

Null association between androgen-deprivation therapy and nonprostate cancer mortality among older men with nonmetastatic prostate cancer

BACKGROUND

Androgen-deprivation therapy (ADT) has been associated with cardiovascular risk factors and the development of cardiovascular disease in men with metastatic prostate cancer. We sought to examine the effect of ADT on nonprostate cancer mortality among patients with nonmetastatic prostate cancer.

METHODS

We performed a population-based, retrospective cohort study of men aged 66 years and older treated with surgery or radiotherapy for nonmetastatic prostate cancer in Ontario, Canada from 2002 to 2009 using administrative datasets (including the Ontario Cancer Registry, Ontario Drug Benefit, and Ontario Health Insurance Plan). Analysis was performed between September 2016 and April 2017. ADT exposure was operationalized as a time-varying binary and cumulative dose exposure. Primary and secondary outcomes were nonprostate cancer mortality and cardiovascular mortality, respectively. The Fine and Gray subdistribution method with generalized estimating equations was used to calculate subdistribution hazard ratios (sdHR), while accounting for competing risks.

RESULTS

We examined 20,651 men treated for nonmetastatic prostate cancer. Median follow-up was 7.4 years and median ADT exposure was 6.4 months. ADT was not significantly associated with nonprostate cancer mortality (sdHR = 0.75, 95% CI: 0.37-1.50) or cardiovascular mortality (sdHR = 1.16, 95% CI: 0.37-3.63) when operationalized as a binary time-varying exposure. Similar results were obtained when we examined ADT cumulative dose exposure.

CONCLUSIONS

ADT is not associated with nonprostate cancer mortality or cardiovascular mortality in a large, population-based cohort of older men with localized prostate cancer treated by surgery or radiation therapy.

Prognostic factors in Chinese patients with prostate cancer receiving primary androgen deprivation therapy: validation of Japan Cancer of the Prostate Risk Assessment (J-CAPRA) score and impacts of pre-existing obesity and diabetes mellitus

PURPOSE

Our aim was to determine the prognostic factors in Chinese patients with prostate cancer receiving primary androgen deprivation therapy (PADT), validate the Japan Cancer of the Prostate Risk Assessment (J-CAPRA) score, and investigate the impacts of pre-existing obesity and diabetes mellitus (DM).

METHODS

The study enrolled Chinese patients diagnosed with prostatic adenocarcinoma and treated with bilateral orchiectomy as PADT at Huashan Hospital, Fudan University (Shanghai, China), from January 2003 to December 2015. The overall survival (OS) and prognostic value of J-CAPRA score, pre-existing obesity, DM, and various clinicopathological variables were analyzed.

RESULTS

Of the 435 patients enrolled, 174 (40.0%) deaths occurred during follow-up; 3- and 5-year OS were 74.0 and 58.9%, respectively. Multivariate analysis identified that higher Gleason score and metastasis were both correlated with worse OS and that higher J-CAPRA score was correlated with worse OS [hazard ratio (HR) 1.110, 95% confidence interval (CI) 1.035-1.190, P = 0.003). Different risk categories based on J-CAPRA score showed good stratification in OS (log-rank P = 0.015). In subgroup analysis, pre-existing obesity as a protective factor in younger patients (age ≤ 65, HR 0.271, 95% CI 0.075-0.980, P = 0.046) and pre-existing DM as a risk factor in older patients (> 75, HR 1.854, 95% CI 1.026-3.351, P = 0.041) for OS were recognized, and the prediction accuracy of J-CAPRA was elevated after incorporating pre-existing obesity and DM.

CONCLUSIONS

The J-CAPRA score presented with good OS differentiation among Chinese patients under PADT. Younger patients (age ≤ 65) had better OS with pre-existing obesity, while older patients (age > 75) had worse OS with pre-existing DM.

[Antihormonal therapy in prostate cancer : Side effects]

Androgen deprivation is still standard therapy for prostate cancer, either as primary androgen deprivation therapy or with the use of secondary hormonal drugs including abiraterone and enzalutamide. However, especially the clinically occult side effects like metabolic changes or cardiovascular complications and effects on the psyche of the patient are often not recognized in daily practice. Active monitoring of such side effects is essential for prevention and early intervention. In addition, the efficacy of androgen deprivation therapies is limited by primary and secondary resistance. The underlying molecular mechanism including splice variants of the androgen receptor in contrast to mutations are usually reversible and should be regarded as a sign of efficacy of the current treatment. Therefore, the clever, timely use of androgen deprivation or even the use of a bipolar androgen therapy should enable reversal of resistance to again render tumor cells sensitive to androgen-deprivation therapy.

Morbidity and Mortality of Locally Advanced Prostate Cancer: A Population Based Analysis Comparing Radical Prostatectomy versus External Beam Radiation

PURPOSE

The management of locally advanced prostate cancer remains controversial. We compared the effect of primary external beam radiation therapy vs radical prostatectomy for locally advanced prostate cancer.

MATERIALS AND METHODS

We retrospectively analyzed the records of 2,935 elderly men 65 years old or older in the SEER (Surveillance, Epidemiology and End Results)-Medicare linked database who underwent external beam radiation therapy or radical prostatectomy for locally advanced prostate cancer. Propensity adjusted Cox proportional hazard and regression models were fit to examine urinary and gastrointestinal toxicities, the use of androgen deprivation therapy, and overall and prostate cancer specific mortality.

RESULTS

A total of 1,429 men (48.69%) underwent radical prostatectomy and had a median followup of 11.47 years (IQR 6.17-17.17) years. A total of 1,506 men (51.31%) received external beam radiation therapy and had a median followup of 7.04 years (IQR 4.11-10.51, p <0.001). Patients treated with radical prostatectomy were at significantly higher risk for urinary and sexual toxicities (HR 1.93, 95% CI 1.66-2.24 and HR 5.50, 95% CI 3.59-8.42, respectively). However, they were at lower risk for gastrointestinal toxicities (HR 0.75, 95% CI 0.65-0.86) than those treated with external beam radiation therapy. Radical prostatectomy was associated with lower odds of androgen deprivation therapy 5 years after primary treatment (OR 0.53, 95% CI 0.41-0.69, p <0.001). External beam radiation therapy was associated with higher overall and prostate specific mortality (HR 1.41, 95% CI 1.09-1.82 and HR 2.35, 95% CI 1.85-2.98, respectively).

CONCLUSIONS

We found significant toxicity and survival differences in elderly men who underwent primary external beam radiation therapy vs radical prostatectomy for locally advanced prostate cancer. While our findings must be interpreted within the limitations of studies that rely on administrative claims, they may yet help tailor individual therapies for elderly men who present with locally advanced prostate cancer.

[Cardiovascular risk patients under androgen deprivation therapy: Lower risk with GnRH antagonists compared to LHRH agonists?]

BACKGROUND

Androgen deprivation therapy (ADT) with gonadotropin-releasing hormone (GnRH) agonists or GnRH antagonists is the mainstay of treatment for metastatic prostate cancer (mCaP). However, ADT is associated with serious cardiovascular events. Only a few studies that directly compare the cardiovascular risk of LHRH agonists versus GnRH antagonists have been published.

OBJECTIVES

This review aims to compare the cardiovascular risk of LHRH agonists versus GnRH antagonists based on the literature.

METHODS

A literature search that considered full publications and abstracts published before December 10, 2014 was performed. Due to their high evidence quality, only meta-analyses and pooled studies were included in this review.

RESULTS

Four studies were included. These investigated the cardiovascular risk of patients receiving an ADT with LHRH agonists and/or GnRH antagonists. However, only one of these directly compared the cardiovascular risk of ADT with LHRH agonists versus GnRH antagonists. This meta-analysis showed a significant reduction in cardiovascular risk for patients receiving a GnRH antagonist compared to those patients receiving a LHRH agonist (HR: 0.597; 95 % CI: 0.380-0.938; P = 0.0253). Subgroup analyses showed that, in particular, patients with pre-existing cardiovascular diseases who were treated with a GnRH antagonist have a significantly lower risk of experiencing a cardiovascular event when compared with patients receiving a GnRH agonist (HR: 0.44; 95 % CI: 0.26-0.74; P = 0.002).

CONCLUSION

In conclusion, GnRH antagonists are associated with a lower risk of cardiovascular events, compared with LHRH agonists, when administered as ADT in CaP patients, and particularly in patients with a history of cardiovascular disease. Thus, patients with a history of cardiovascular disease may benefit from ADT with a GnRH antagonist.

[Cardiovascular risk of androgen deprivation therapy for treatment of hormone-dependent prostate cancer : Differences between GnRH antagonists and GnRH agonists]

BACKGROUND

Several studies have indicated that reduction of testosterone levels in patients with prostate cancer undergoing androgen deprivation therapy (ADT) with gonadotropin-releasing hormone (GnRH) agonists can be associated with an increased risk of cardiovascular events. The GnRH antagonists have a different mode of action compared with GnRH agonists and may be preferred in ADT for patients with cardiovascular disease.

OBJECTIVE

This review article discusses potential mechanisms underlying the development of cardiovascular events associated with ADT when using GnRH agonists and explains the differences in mode of action between GnRH agonists and GnRH antagonists. Additionally, relevant studies are presented and practical recommendations for the clinical practice are provided.

MATERIAL AND METHODS

A literature search was performed. Full publications and abstracts published in the last 10 years up to September 2015 were considered to be eligible.

RESULTS

The GnRH antagonists were associated with a decreased risk of cardiovascular events compared with GnRH agonists in prostate cancer patients undergoing ADT and particularly in patients with cardiovascular risk factors or a history of cardiovascular disease. This decrease may be due to the different mode of action of GnRH antagonists compared with GnRH agonists.

CONCLUSION

Prostate cancer patients with either cardiovascular disease or an increased risk of experiencing a cardiovascular event undergoing ADT should be preferentially treated with GnRH antagonists.

Relationship between androgen deprivation therapy and community-acquired respiratory infections in patients with prostate cancer

OBJECTIVES

To investigate the dose-dependent effect of androgen deprivation therapy on community-acquired respiratory infections in patients with localized prostate cancer.

METHODS

We identified 52 905 men diagnosed with localized prostate cancer within the Surveillance, Epidemiology and End Results-Medicare database between 1991 and 2006. We compared those who did not receive androgen deprivation therapy with those who received androgen deprivation therapy within 2 years of diagnosis, calculated as monthly equivalent doses (<7, 7-11, >11 doses), or orchiectomy. Adjusted Cox hazard models were fitted to predict the risk of community-acquired respiratory infections (acute sinusitis, acute bronchitis, [severe] pneumonia) in patients treated with medical androgen deprivation therapy versus orchiectomy versus none.

RESULTS

Overall, 43.4% received medical androgen deprivation therapy. These patients more likely experienced respiratory events compared with those who did not receive androgen deprivation therapy or who underwent orchiectomy (62.2% vs 54.5% vs 47.8%, P < 0.001). The risk of experiencing any respiratory event increased with the number of doses received. For example, men receiving >11 doses of androgen deprivation therapy were at greatest risk of acute sinusitis, acute bronchitis and pneumonia (HR 1.13, 1.26 and 1.15, respectively, all P < 0.001), except severe pneumonia. Furthermore, we did not detect any relationship between orchiectomy and respiratory events. Study limitations include the utilization of a retrospective population-based dataset.

CONCLUSIONS

Increased exposure to medical androgen deprivation therapy for men with localized prostate cancer is associated with a higher risk of community-acquired respiratory infections. Our results suggest that respiratory complications represent potentially underreported complications of medical androgen deprivation therapy.

Binding site of activators of the cystic fibrosis transmembrane conductance regulator in the nucleotide binding domains

The use of substances that could activate the defective chloride channels of the mutant cystic fibrosis transmembrane conductance regulator (CFTR) has been suggested as possible therapy for cystic fibrosis. Using epithelia formed by cells stably transfected with wildtype or mutant (G551D, G1349D) CFTR, we estimated the apparent dissociation constant, K(D), of a series of CFTR activators by measuring the increase in the apical membrane current. Modification of apparent K(D) of CFTR activators by mutations of the nucleotide-binding domains (NBDs) suggests that the binding site might be in these regions. The human NBD structure was predicted by homology with murine NBD1. An NBD1-NBD2 complex was constructed by overlying monomers to a bacterial ABC transporter NBD dimer in the "head-to-tail" conformation. Binding sites for CFTR activators were predicted by molecular docking. Comparison of theoretical binding free energy estimated in the model to free energy estimated from the apparent dissociation constants, K(D), resulted in a remarkably good correlation coefficient for one of the putative binding sites, located in the interface between NBD1 and NBD2.