Men's Sexual Health Questionnaire score changes vs spontaneous sexual adverse event reporting in men treated with dutasteride/tamsulosin combination therapy for lower urinary tract symptoms secondary to benign prostatic hyperplasia: A post hoc analysis of a prospective, randomised, placebo-controlled study

AIM

To assess the impact of baseline characteristics on Men's Sexual Health Questionnaire (MSHQ) total scores and to evaluate the clinical relevance of MSHQ changes and their association with spontaneously reported sexual adverse events (SexAEs) in patients with benign prostatic hyperplasia.

METHODS

This was a post hoc analysis of the Phase 4 FDC116115 study, in which patients aged ≥50 years were randomised 1:1 to receive a fixed-dose combination of dutasteride 0.5 mg and tamsulosin 0.4 mg (DUT-TAM FDC), or placebo. End-points included: change in MSHQ total scores by baseline characteristics and SexAEs; cumulative distribution function for change from baseline to month 12 in MSHQ total score and the ejaculation, erection, satisfaction and sexual desire (libido) domain scores; and relationship between changes in MSHQ scores and SexAEs.

RESULTS

The intent-to-treat population comprised 489 patients (DUT-TAM FDC, n = 243; placebo, n = 246). The mean reduction in total MSHQ score was greater in patients with SexAEs across both groups, compared with patients without SexAEs. Most patients reporting any SexAE (86% DUT-TAM FDC, 67% placebo) had a worsening of the MSHQ total score at month 12 compared with baseline. Specifically, 90% (DUT-TAM FDC) and 75% (placebo) of patients reporting an ejaculation SexAE and 73% (DUT-TAM FDC) and 87% (placebo) of patients reporting an erection SexAE had a worsening of MSHQ ejaculation and erection domain scores, respectively, at month 12. A threshold effect for incident SexAE was observed; patients showing a decrease of approximately 6-10 points in the total MSHQ score were more likely to report SexAEs.

CONCLUSION

Findings support the clinical utility of the MSHQ tool in assessing the impact of DUT-TAM on sexual function by linking numerical changes in MSHQ scores to spontaneously reported SexAEs for the first time. The threshold effect for incidence of SexAEs warrants further investigation to determine its clinical relevance.

Evaluation of the impact of dutasteride/tamsulosin combination therapy on libido in sexually active men with lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH): A post hoc analysis of a prospective randomised placebo-controlled study

AIMS

Five-α reductase inhibitor (5ARI) therapy has been associated with sexual dysfunction in some patients. This study assessed the impact of a fixed-dose combination of the 5ARI dutasteride 0.5 mg and the α₁ -adrenoceptor antagonist tamsulosin 0.4 mg (DUT-TAM FDC) on Men's Sexual Health Questionnaire (MSHQ) domain scores in patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH).

METHODS

This was a post hoc analysis of a double-blind, randomised, placebo-controlled, parallel-group, multicentre study in sexually active patients, aged ≥50 years, with a confirmed clinical diagnosis of BPH. Sexual activity, sexual desire, and bother domain scores of the MSHQ were assessed at baseline and at Months 1, 3, 6, 9, and 12. Correlation between MSHQ sexual activity/desire scores and ejaculation, erection, and satisfaction domains at baseline was also evaluated.

RESULTS

In the intent-to-treat population (N = 489), 243 and 246 patients were randomised to DUT-TAM FDC and placebo groups, respectively. Compared with placebo, DUT-TAM FDC therapy resulted in statistically significant reductions (worsening) from baseline in adjusted mean MSHQ sexual activity and bother domain scores at Months 1, 3, 6, 9, and 12 (all P < 0.05) and in adjusted mean MSHQ sexual desire domain scores at Months 6, 9, and 12 (all P < 0.05). Significant moderate correlations in the expected direction were observed at baseline between the sexual activity/desire domains and the ejaculation, erection, and satisfaction domains (P < 0.0001).

CONCLUSIONS

These findings help clarify the degree and impact of libido changes in sexually active men treated with DUT-TAM FDC and may support clinical decision-making.

Albiglutide efficacy and safety in the Latino/Hispanic subpopulation for the integrated phase III program

OBJECTIVE

to evaluate the efficacy and safety of albiglutide compared with placebo and active comparators from an integrated trial subpopulation of Latino/Hispanic patients whose type 2 diabetes mellitus (T2DM) was inadequately controlled on their current regimen of diet and exercise, with or without oral antidiabetic drugs (OADs) and/or insulin.

METHODS

Latino/Hispanic patient subpopulations (N = 1204) across 7 phase III albiglutide studies (N = 4400) were evaluated post-hoc for efficacy and safety. Comparators were placebo, sulfonylureas, insulin, thiazolidinediones, and dipeptidyl peptidase-4 inhibitors. Glycatedhemoglobin (HbA_1c) change from baseline to the time of the primary endpoint assessment (from 26 to 104 weeks) was evaluated in patients on diet and exercise and/or OADs, with or without insulin. Patients were allowed to continue in the study if hyperglycemic rescue was required, according to a prespecified algorithm and at the discretion of the investigator.

RESULTS

At baseline in the Latino/Hispanic subpopulation, the mean HbA_1c was 8.3%, mean age was 53 years, mean body mass index was 32 kg/m², and mean duration of T2DM was 8.0 years. The primary endpoint of mean HbA_1c difference (albiglutide - placebo) was -0.94% for the Latino/Hispanic subpopulation and -0.86% (p < 0.001) for the overall phase III population. Changes in fasting plasma glucose mirrored those of HbA_1c. Weight loss with albiglutide was numerically greater than with OADs and insulin in both populations, but it was smaller than with liraglutide. Within the Latino/Hispanic subpopulation, more injection-site reactions were reported with albiglutide vs all comparators, while gastrointestinal and hypoglycemic adverse events were comparable between the two groups, and the latter was uncommon when used without insulin and/or a sulfonylurea.

CONCLUSIONS

In the Latino/Hispanic population, albiglutide resulted in effective lowering of glucose and modest weight loss, and it was generally well tolerated.

Weekly glucagon-like peptide-1 receptor agonist albiglutide as monotherapy improves glycemic parameters in Japanese patients with type 2 diabetes mellitus: A randomized, double-blind, placebo-controlled study

AIMS/INTRODUCTION

The present phase 3, randomized, double-blind 24-week study with extension to 1 year assessed the efficacy and safety of albiglutide compared with placebo in Japanese patients with type 2 diabetes mellitus inadequately controlled by diet and exercise with or without a single oral antidiabetic drug.

MATERIALS AND METHODS

Patients received weekly albiglutide 30 mg (n = 160), albiglutide 50 mg (n = 150) or a placebo switched to albiglutide 30 mg after 24 weeks (n = 77). Open-label daily liraglutide 0.9 mg (n = 103) was included as a reference. Oral antidiabetic drug use was discontinued before baseline. The primary end-point was 24-week change from baseline in glycated hemoglobin (HbA1c). Secondary end-points included fasting plasma glucose, bodyweight and adverse events.

RESULTS

At 24 weeks, mean HbA1c changes from baseline were -1.10, -1.30, and 0.25% for albiglutide 30, 50 mg and placebo, respectively (P vs placebo <0.0001 for both albiglutide doses), -1.19% for liraglutide. Decreases in HbA1c with albiglutide were sustained through the study. Mean fasting plasma glucose decreased by ≥20 mg/dL, and the mean change in bodyweight was ≤0.5 kg through 1 year across groups. Most commonly reported adverse events were nasopharyngitis, constipation and nausea. The incidence of adverse events was higher in active treatment groups than in the placebo group. Few hypoglycemia events were reported; no patient withdrew as a result of hypoglycemia. No new safety signals were detected.

CONCLUSIONS

Albiglutide monotherapy achieved clinically significant decreases in HbA1c and fasting plasma glucose with good tolerability in Japanese patients with type 2 diabetes mellitus inadequately controlled by diet and exercise with or without a single oral antidiabetic drug.

Albiglutide, a weekly GLP-1 receptor agonist, improves glycemic parameters in Japanese patients with type 2 diabetes over 1 year when added to single oral antidiabetic drugs

OBJECTIVE

To evaluate the safety and efficacy of once weekly albiglutide added to a single oral antidiabetic drug (OAD) in Japanese patients with inadequately controlled type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

In this phase 3, 1 year study (NCT01777282), patients (N = 374) received albiglutide 30 mg plus a single OAD (sulfonylurea [n = 120], biguanide [n = 67)], glinide [n = 65], thiazolidinedione [n = 61], or α-glucosidase inhibitor [n = 61]). Albiglutide could be increased to 50 mg after Week 4, based on glycemic criteria. Primary endpoints were the incidence of adverse events (AEs) and hypoglycemia; secondary endpoints were changes from baseline at Week 52 in HbA_1c and fasting plasma glucose (FPG), proportion of patients achieving HbA_1c ≤7.0%, and withdrawals due to hyperglycemia.

RESULTS

On-therapy AEs occurred in 78.6% of patients and serious AEs in 2.1%. Common AEs were nasopharyngitis (32.6%), constipation (7.2%), and diabetic retinopathy (5.3%). No serious AEs occurred more than once or were reported in >1 patient. Hypoglycemia occurred in 6.4% of patients, mostly in the albiglutide + sulfonylurea (14.2%) and the albiglutide + glinide (6.2%) groups. Albiglutide was uptitrated in 53.2% of patients. Mean baseline HbA_1c was 8.1%. Mean decreases from baseline in HbA_1c were observed with the addition of albiglutide to thiazolidinediones (-1.42%), α-glucosidase inhibitors (-1.39%), sulfonylureas (-1.04%), glinides (-0.95%), and biguanides (-0.94%). HbA_1c of <7% in >50% of patients and mean reductions in FPG were achieved in all groups. Mean changes from baseline in body weight ranged from +0.52 kg (albiglutide + thiazolidinedione) to -0.33 kg (albiglutide + biguanide). Limitations of the study included open label treatment that was not randomized.

CONCLUSIONS

When combined with a single OAD in Japanese patients with inadequately controlled T2DM, albiglutide led to favorable changes in all glycemic parameters, with minor changes in body weight depending on the background OAD. No new safety concerns were noted.

Gastrointestinal safety across the albiglutide development programme

Gastrointestinal (GI) adverse events (AEs) are the most frequently reported treatment-related AEs associated with glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of type 2 diabetes mellitus. The GI safety of albiglutide, a once-weekly GLP-1RA, was assessed using data from five phase III studies. In a pooled analysis of four placebo-controlled trials, the most common GI AEs were diarrhoea (albiglutide, 14.5% vs. placebo, 11.5%) and nausea (albiglutide, 11.9% vs. placebo, 10.3%), with most patients experiencing 1-2 events. The majority were mild or moderate in intensity and their median duration was 3-4 days. Vomiting occurred in 4.9% of patients in the albiglutide vs. 2.6% in the placebo group. For both albiglutide and placebo, serious GI AEs (2.0% vs. 1.5%) and withdrawals attributable to GI AEs (1.7% vs. 1.5%) were low. In a 32-week trial of albiglutide 50 mg weekly versus liraglutide 1.8 mg daily, nausea occurred in 9.9% of patients in the albiglutide group vs. 29.2% in the liraglutide group. Vomiting occurred in 5.0% in the albiglutide vs. 9.3% in the liraglutide group. In conclusion, albiglutide has an acceptable GI tolerability profile, with nausea and vomiting rates slightly higher than those for placebo but lower than those for liraglutide.

Nocturia improvement in the combination of Avodart(®) and tamsulosin (CombAT) study

PURPOSE

The purpose of the study was to assess the impact of dutasteride plus tamsulosin combination therapy, compared with dutasteride or tamsulosin monotherapy, on nocturia in men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH) using data from the 4-year CombAT study.

METHODS

Nocturia was assessed using Question 7 of the International Prostate Symptom Score questionnaire. Efficacy measures included as follows: mean change in nocturia at 3-month intervals up to 48 months; proportion of patients with improvement/worsening in nocturia; nocturnal voiding frequency at baseline and study end, overall and by baseline subgroups; and nocturnal voiding frequency <2 at study end in patients with a baseline score ≥ 2.

RESULTS

In total, 4,722 patients with a mean age of 66 years were included. Mean nocturia improvements were significantly superior (p ≤ 0.01) with combination therapy than with either monotherapy (adjusted mean change from baseline in IPSS Question 7 score at month 48: combination therapy -0.5, dutasteride -0.4, tamsulosin -0.3). Reduction in nocturia score with combination therapy was significantly (p ≤ 0.01) better than tamsulosin monotherapy across all baseline subgroups tested, except for men with previous 5ARI use. Among those with a baseline IPSS Q7 score ≥ 2, more patients with combination therapy had a score <2 at month 48 (34 %) compared with dutasteride (30 %, p = 0.018) or tamsulosin (26 %, p < 0.0001).

CONCLUSIONS

Combination therapy provided greater improvements and less worsening of nocturia compared with both dutasteride and tamsulosin monotherapies. These analyses are the first to show greater improvement with a 5ARI/α-blocker combination versus either agent alone for the management of nocturia in patients with LUTS/BPH.

Influence of baseline variables on changes in International Prostate Symptom Score after combined therapy with dutasteride plus tamsulosin or either monotherapy in patients with benign prostatic hyperplasia and lower urinary tract symptoms: 4-year results of the CombAT study

OBJECTIVE

To examine, using post hoc analysis, the influence of baseline variables on changes in international prostate symptom score (IPSS), maximum urinary flow rate (Qmax ) and IPSS quality of life (QoL) in patients with moderate-to-severe lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH) treated with either the α-blocker tamsulosin or the dual 5-alpha reductase inhibitor dutasteride, alone or in combination, as part of the 4-year Combination of Avodart and Tamsulosin (CombAT) study.

PATIENTS AND METHODS

CombAT was a 4-year, multicentre, randomized, double-blind, parallel-group study in 4844 men ≥50 years of age with a clinical diagnosis of BPH by medical history and physical examination, an IPSS ≥12 points, prostate volume (PV) ≥30 mL, total serum PSA level ≥1.5 ng/mL, and Qmax >5 mL/s and ≤15 mL/s with a minimum voided volume ≥125 mL. Eligible subjects were randomized to receive oral daily tamsulosin, 0.4 mg; dutasteride, 0.5 mg; or a combination of both. Baseline variable subgroups analysed were as follows: PV (30 to <40; 40 to <60; 60 to <80; ≥80 mL), PSA level (1.5 to <2.5; 2.5 to <4; ≥4 ng/mL), age (median: <66, ≥66 years), IPSS (median: <16, ≥16; IPSS thresholds, <20, ≥20), IPSS QoL score (question 8, Q8) (median: <4, ≥4), Qmax (median: <10.4, ≥10.4 mL/s), BPH impact index (BII) (median: <5, ≥5) and body mass index (BMI, median: <26.8, ≥26.8 kg/m(2) ). Within each baseline variable subgroup, changes in IPSS, Qmax and IPSS QoL Q8 from baseline were evaluated using a generalized linear model with effects for baseline IPSS, Qmax or IPSS QoL Q8 and treatment group at each post-baseline assessment up to and including the month 48 visit using a last observation carried forward approach. The treatment comparisons of combination therapy vs dutasteride and combination therapy vs tamsulosin were performed from the general linear model with statistical significance defined as P ≤ 0.01.

RESULTS

Combination therapy resulted in a significantly greater improvement from baseline IPSS at 48 months vs tamsulosin monotherapy across all baseline subgroups. The benefit of combination therapy over dutasteride was confined to groups with lower baseline PV (<60 mL) and PSA (<4 ng/mL). In groups with baseline PV ≥60 mL and PSA ≥4 ng/mL, dutasteride and combination therapy show similar improvements in symptoms. Combination therapy resulted in significantly improved Qmax compared with tamsulosin but not dutasteride monotherapy. Qmax improvement appeared to increase with PV and PSA level in combination therapy subjects. The proportion of subjects with an IPSS QoL ≤2 (at least mostly satisfied) at 48 months was significantly higher with combination therapy than with dutasteride for subgroups with PV 40-60 mL and PSA level <4 ng/mL and than with tamsulosin for all PSA subgroups and PV subgroups ≥40 mL.

CONCLUSIONS

CombAT data support the use of long-term combination therapy with dutasteride and tamsulosin in patients considered at risk for progression of BPH, as determined by high PV (≥30 mL) and high PSA (≥1.5 ng/mL). Combination therapy, dutasteride monotherapy and tamsulosin monotherapy all improved Qmax , but to different extents (combination therapy > dutasteride >> tamsulosin), suggesting that dutasteride contributes most to the Qmax benefit in combination therapy. Combination therapy provided consistent improvement over tamsulosin in LUTS across all analysed baseline variables at 48 months. Compared with dutasteride, the superiority of combination therapy at 48 months was shown in patients with PV <60 mL or PSA <4 ng/mL.

The effect of dutasteride on the detection of prostate cancer: A set of meta-analyses

BACKGROUND

Dutasteride has been shown to significantly improve symptoms of benign prostatic hyperplasia (BPH) and reduce clinical progression. Recent data from studies evaluating 5-alpha reductase inhibitors (5-ARIs) for the prevention of prostate cancer, however, suggest 5ARIs, including dutasteride, may be associated with increased incidence of Gleason 8-10 prostate tumours. This meta-analysis was undertaken to quantify the effect of dutasteride on detection of prostate cancer and high-grade prostate cancer.

METHODS

Our meta-analysis includes data from GlaxoSmithKline-sponsored phase III randomized clinical trials (with a study duration of ≥2 years) evaluating the effect of dutasteride, alone or in combination with tamsulosin, to treat BPH or to reduce the risk of prostate cancer. The incidence of prostate cancer, including Gleason 7-10 and Gleason 8-10, for patients taking either dutasteride, dutasteride plus tamsulosin, tamsulosin alone, or placebo, were evaluated using the Mantel-Haenszel Risk Ratio (MHRR) method of conducting meta-analyses.

RESULTS

The meta-analysis demonstrated that in a population with symptomatic BPH and/or at increased risk of prostate cancer, a statistically significant lower number of detectable prostate cancers was found in men taking dutasteride compared to control groups (MHRR: 0.66, 95% CI 0.52-0.85). In our analysis, there was no increased risk for Gleason 7-10 (MHRR: 0.83, 95% CI 0.56-1.21) or Gleason 8-10 prostate cancers (MHRR: 0.99, 95% CI 0.39-2.53) in men taking dutasteride over control groups. There were several limitations that need to be considered when interpreting these results.

CONCLUSION

These data provide support for the continued use of dutasteride in the treatment of symptomatic BPH patients.

Dutasteride reduces prostatitis symptoms compared with placebo in men enrolled in the REDUCE study

PURPOSE

Men at risk for prostate cancer may concurrently experience chronic prostatitis or pelvic pain. We evaluated the effect of dutasteride on prostatitis-like symptoms in the REDUCE study population.

MATERIALS AND METHODS

REDUCE was a 4-year, randomized, double-blind, placebo controlled study of prostate cancer risk reduction with 0.5 mg dutasteride vs placebo in men 50 to 75 years old with prostate specific antigen 2.5 to 10 ng/ml and a negative prostate biopsy in the previous 6 months. In this analysis we investigated change from baseline in Chronic Prostatitis Symptom Index in men with prostatitis-like pain (Chronic Prostatitis Symptom Index pain subscore 5 or greater) and prostatitis-like syndrome (perineal or ejaculatory pain plus Chronic Prostatitis Symptom Index pain subscore 4 or greater), the proportion of subjects with at least a moderate Chronic Prostatitis Symptom Index response (6-unit or greater improvement) and reports of new onset clinical prostatitis.

RESULTS

Of 5,379 men with a total baseline Chronic Prostatitis Symptom Index score 678 (12.6%) had prostatitis-like pain and 427 (7.9%) had prostatitis-like syndrome. Chronic Prostatitis Symptom Index total score decreased significantly at 48 months in the dutasteride group vs placebo in men with prostatitis-like pain (p <0.0001) and with prostatitis-like syndrome (t test p = 0.03). There were significantly more Chronic Prostatitis Symptom Index responders with dutasteride vs placebo in the prostatitis-like pain (49% vs 37%, respectively, p = 0.0033) and prostatitis-like syndrome (46% vs 35%, Fisher's exact test p = 0.0265) subgroups. Prostatitis was reported as an adverse event by significantly more men randomized to placebo (3.6%) than to dutasteride (2.5%, p = 0.003).

CONCLUSIONS

Long-term dutasteride therapy resulted in improvement in prostatitis related symptoms in older men with an increased prostate specific antigen.

Comparison of dutasteride and finasteride for treating benign prostatic hyperplasia: the Enlarged Prostate International Comparator Study (EPICS)

OBJECTIVE

• To assess the efficacy and safety of dutasteride compared with finasteride in treating men with symptomatic benign prostatic hyperplasia (BPH) for 12 months.

PATIENTS AND METHODS

• The Enlarged Prostate International Comparator Study was a multicentre, randomized, double-blind, 12-month, parallel-group study. • Men aged ≥ 50 years with a clinical diagnosis of BPH received once-daily treatment with dutasteride 0.5 mg (n= 813) or finasteride 5 mg (n= 817). After a 4-week placebo run-in period, patients were randomized to receive dutasteride or finasteride for 48 weeks, followed by an optional 24-month, open-label phase, during which patients received dutasteride 0.5 mg once daily. • The primary endpoint was change in prostate volume, and the secondary endpoints included improvement in American Urological Association Symptom Index (AUA-SI) scores, improvement in maximum urinary flow rate (Q(max)) and long-term safety in the 24-month open-label phase.

RESULTS

• Both dutasteride and finasteride were effective at reducing prostate volume with no significant difference between the two treatments during the study. • Similar reductions in mean AUA-SI scores and Q(max) were also observed for men in both treatment groups. • A similar percentage of adverse events was experienced by patients of both treatment groups, and no new adverse events were reported in the open-label phase.

CONCLUSION

• Dutasteride and finasteride, when administered for 12 months, were similarly effective in reducing prostate volume and improving Q(max) and urinary symptoms associated with BPH in men with an enlarged prostate.

Clinical outcomes after combined therapy with dutasteride plus tamsulosin or either monotherapy in men with benign prostatic hyperplasia (BPH) by baseline characteristics: 4-year results from the randomized, double-blind Combination of Avodart and Tamsulosin (CombAT) trial

OBJECTIVE

• To investigate the influence of baseline variables on the 4-year incidence of acute urinary retention (AUR), benign prostatic hyperplasia (BPH)-related surgery and overall clinical progression in men treated with tamsulosin, dutasteride, or a combination of both.

PATIENTS AND METHODS

• The 4-year Combination of Avodart® and Tamsulosin (CombAT) study was a multicenter, randomized, double-blind, parallel-group study of clinical outcomes in men aged ≥ 50 years with symptomatic (International Prostate Symptom Score [IPSS]≥ 12) BPH, with prostate-specific antigen (PSA) levels of ≥ 1.5 ng/mL and ≤ 10 ng/mL, and a prostate volume (PV) of ≥ 30 mL. • Eligible patients received tamsulosin 0.4 mg, dutasteride 0.5 mg, or a combination of both. • The primary endpoint was time to first AUR or BPH-related surgery. Secondary endpoints included clinical progression of BPH and symptoms. Posthoc analyses of the influence of baseline variables (including age, IPSS health-related quality of life [HRQL], PV, PSA, IPSS, peak urinary flow rate [Q(max) ] and body-mass index [BMI]) on the incidence of AUR or BPH-related surgery, clinical progression of BPH, and symptoms were performed.

RESULTS

• There were 4844 men in the intent-to-treat population. Overall baseline characteristics were similar across all patient groups. • Regardless of baseline subgroup, the incidence of AUR or BPH-related surgery was higher in men treated with tamsulosin than in those treated with dutasteride or combined therapy. • Combined therapy was statistically better than tamsulosin in reducing the risk of AUR or BPH-related surgery in subgroups of baseline PV > 42.0 mL, in all subgroups of baseline PSA level, and all other baseline subgroups (P ≤ 0.001). • Across treatment groups, the incidence of clinical progression was highest in men with a baseline IPSS of < 20 or IPSS HRQL score of < 4. The incidence of clinical progression was also higher in men receiving tamsulosin than dutasteride or combined therapy in all baseline subgroups, except for men with a baseline PV of < 40 mL. Combined therapy reduced the relative risk (RR) of clinical progression compared with tamsulosin across all baseline subgroups and compared with dutasteride across most baseline subgroups. • Symptom deterioration was the most common progression event in each treatment group regardless of baseline subgroup, except in those men with an IPSS of ≥ 20 at baseline. Combined therapy reduced the RR of symptom deterioration compared with tamsulosin across all but one baseline subgroup (the reduction was not significant for men with a baseline PV of < 40 mL) and compared with dutasteride in most subgroups.

CONCLUSIONS

• Men with a baseline PV of ≥ 40 mL and any baseline PSA level of ≥1.5 ng/mL had greater reductions in the RR of AUR or BPH-related surgery and greater reductions in the RR of clinical progression and symptom deterioration on combined therapy or dutasteride monotherapy than on tamsulosin monotherapy. • These analyses support the long-term use of combined therapy with dutasteride plus tamsulosin in men with moderate-to-severe BPH symptoms and a slightly enlarged prostate.

Effect of dutasteride on prostate biopsy rates and the diagnosis of prostate cancer in men with lower urinary tract symptoms and enlarged prostates in the Combination of Avodart and Tamsulosin trial

BACKGROUND

A 23% relative risk reduction (RRR) in prostate cancer (PCa) was shown in men receiving dutasteride in the 4-yr Reduction by Dutasteride of Prostate Cancer Events study, in whom biopsies were protocol dependent.

OBJECTIVE

Our aim was to explore PCa risk reduction in men with benign prostatic hyperplasia (BPH) from the Combination of Avodart and Tamsulosin (CombAT) study, in which biopsies were undertaken for cause.

DESIGN, SETTING, AND PARTICIPANTS

CombAT was a 4-yr randomized double-blind parallel group study in 4844 men ≥50 yr of age with clinically diagnosed moderate to severe BPH, International Prostate Symptom Score ≥12, prostate volume ≥30 ml, and serum prostate-specific antigen (PSA) 1.5-10 ng/ml. Men underwent annual PSA measurement and digital rectal examination (DRE), and prostate biopsies were performed for cause.

INTERVENTION

All patients took tamsulosin 0.4 mg/d, dutasteride 0.5 mg/d, or a combination of both.

MEASUREMENTS

The primary end point was incidence of PCa. Secondary end points included postbaseline prostate biopsy rates and Gleason score of cancers.

RESULTS AND LIMITATIONS

Dutasteride (alone or in combination with tamsulosin) was associated with a 40% RRR of PCa diagnosis compared with tamsulosin monotherapy (95% confidence interval, 16-57%; p=0.002) and a 40% reduction in the likelihood of biopsy. There were similar reductions in low- and high-grade Gleason score cancers. The biopsy rate in the groups receiving dutasteride trended toward a higher diagnostic yield (combination: 29%, dutasteride: 28%, tamsulosin: 24%). One limitation was the lack of a standardized approach to PCa diagnosis and grading.

CONCLUSIONS

Dutasteride, alone or in combination with tamsulosin, significantly reduced the relative risk of PCa diagnosis in men with BPH undergoing annual DRE and PSA screening. Consistent with the increased usefulness of PSA for PCa detection, men receiving dutasteride had a numerically lower biopsy rate and higher yield of PCa on biopsy.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT00090103 (http://www.clinicaltrials.gov/ct2/show/NCT00090103).

AUTORADIOGRAPHIC STUDY OF SUGAR AND AMINO ACID ABSORPTION BY EVERTED SACS OF HAMSTER INTESTINE

Autoradiographs were prepared from frozen sections of everted sacs of hamster jejunum which had been incubated in vitro with C¹⁴- or H³-labeled sugars and amino acids. When such tissue was incubated in 1 mM solutions of L-valine or L-methionine, columnar absorptive cells at tips of villi accumulated these amino acids to concentrations ranging from 5 to 50 millimoles per liter of cells. Quantitative data were obtained by microdensitometry of C¹⁴ autoradiographs. Similar, though less striking, results were obtained with the sugars: galactose, 3-0-methylglucose, α-methylglucoside, and 6-deoxyglucose. In all cases the marked "step-up" in concentration occurred near the brush border of the cell, and a "step-down" in concentration occurred at the basal pole of the cell. Known inhibitors of intestinal absorption, e.g., phlorizin in the case of sugars, blocked the concentrative step at the luminal border of the absorptive cell. It is inferred from these data that active transport systems for sugars and amino acids reside in the brush border region of the cell. Additional evidence suggests that the basal membrane of the cell may be the site of both a diffusion barrier and a weak transport system directed into the cell.

Effect of dutasteride on the risk of prostate cancer

BACKGROUND

We conducted a study to determine whether dutasteride reduces the risk of incident prostate cancer, as detected on biopsy, among men who are at increased risk for the disease.

METHODS

In this 4-year, multicenter, randomized, double-blind, placebo-controlled, parallel-group study, we compared dutasteride, at a dose of 0.5 mg daily, with placebo. Men were eligible for inclusion in the study if they were 50 to 75 years of age, had a prostate-specific antigen (PSA) level of 2.5 to 10.0 ng per milliliter, and had had one negative prostate biopsy (6 to 12 cores) within 6 months before enrollment. Subjects underwent a 10-core transrectal ultrasound-guided biopsy at 2 and 4 years.

RESULTS

Among 6729 men who underwent a biopsy or prostate surgery, cancer was detected in 659 of the 3305 men in the dutasteride group, as compared with 858 of the 3424 men in the placebo group, representing a relative risk reduction with dutasteride of 22.8% (95% confidence interval, 15.2 to 29.8) over the 4-year study period (P<0.001). Overall, in years 1 through 4, among the 6706 men who underwent a needle biopsy, there were 220 tumors with a Gleason score of 7 to 10 among 3299 men in the dutasteride group and 233 among 3407 men in the placebo group (P=0.81). During years 3 and 4, there were 12 tumors with a Gleason score of 8 to 10 in the dutasteride group, as compared with only 1 in the placebo group (P=0.003). Dutasteride therapy, as compared with placebo, resulted in a reduction in the rate of acute urinary retention (1.6% vs. 6.7%, a 77.3% relative reduction). The incidence of adverse events was similar to that in studies of dutasteride therapy for benign prostatic hyperplasia, except that in our study, as compared with previous studies, the relative incidence of the composite category of cardiac failure was higher in the dutasteride group than in the placebo group (0.7% [30 men] vs. 0.4% [16 men], P=0.03).

CONCLUSIONS

Over the course of the 4-year study period, dutasteride reduced the risk of incident prostate cancer detected on biopsy and improved the outcomes related to benign prostatic hyperplasia. (ClinicalTrials.gov number, NCT00056407.)

The effect of dutasteride on the peripheral and transition zones of the prostate and the value of the transition zone index in predicting treatment response

PURPOSE

We determined the effects of dutasteride on transition and peripheral zone volume, and the clinical value of the transition zone index in men with benign prostatic hyperplasia.

MATERIALS AND METHODS

A total of 2,802 men 50 years or older with diagnosed benign prostatic hyperplasia, American Urological Association symptom index score 12 or greater, total prostate volume 30 cc or greater, prostate specific antigen 1.5 ng/ml or greater and 10 ng/ml or less, and peak urinary flow rate 15 ml per second or less were randomized to receive 0.5 mg dutasteride daily or placebo for 2 years. Total prostate and transition zone volume was measured with transrectal ultrasound at baseline and 4 times during the 2-year period. Peripheral zone volume (total prostate volume minus transition zone volume) and the transition zone index (transition zone volume/total prostate volume) were calculated. Patients were stratified into tertiles according to baseline total prostate and transition zone volume, and the transition zone index.

RESULTS

At 24 months dutasteride significantly decreased total prostate volume from baseline (p <0.0001). There were similar decreases in transition and peripheral zone volume (approximately 25%). In men receiving placebo high baseline total prostate and transition zone volume, and transition zone index were associated with poor 2-year outcomes, ie a low peak urinary flow rate, high American Urological Association symptom index scores, and an increased frequency of acute urinary retention and benign prostatic hyperplasia related surgery. Improvements in outcomes with dutasteride vs placebo were greatest in men with the highest baseline total prostate and transition zone volume, and transition zone index. In men with low (30 to less than 42 cc) and intermediate (42 to less than 58 cc) baseline total prostate volume the benefits of dutasteride therapy were only significant in the intermediate (0.4 to less than 0.55) and high (0.55 to less than 1.0) transition zone index tertiles.

CONCLUSIONS

Total prostate and transition zone volume, and the transition zone index are directly related to benign prostatic hyperplasia progression. The transition zone index may add value to transition zone volume alone for predicting outcomes. Dutasteride decreased transition and peripheral zone volume equally, supporting a known therapeutic role in benign prostatic hyperplasia and a possible preventive role in prostate cancer.

Marked suppression of dihydrotestosterone in men with benign prostatic hyperplasia by dutasteride, a dual 5alpha-reductase inhibitor

Dihydrotestosterone (DHT) is the primary metabolite of testosterone in the prostate and skin. Testosterone is converted to DHT by 5alpha-reductase, which exists in two isoenzyme forms (types 1 and 2). DHT is associated with development of benign prostatic hyperplasia (BPH), and reduction in its level with 5alpha-reductase inhibitors improves the symptoms associated with BPH and reduces the risk of acute urinary retention and prostate surgery. A selective inhibitor of the type 2 isoenzyme (finasteride) has been shown to decrease serum DHT by about 70%. We hypothesized that inhibition of both isoenzymes with the dual inhibitor dutasteride would more effectively suppress serum DHT levels than selective inhibition of only the type 2 isoenzyme. A total of 399 patients with BPH were randomized to receive once-daily dosing for 24 wk of dutasteride (0.01, 0.05, 0.5, 2.5, or 5.0 mg), 5 mg finasteride, or placebo. The mean percent decrease in DHT was 98.4 +/- 1.2% with 5.0 mg dutasteride and 94.7 +/- 3.3% with 0.5 mg dutasteride, significantly lower (P < 0.001) and with less variability than the 70.8 +/- 18.3% suppression observed with 5 mg finasteride. Mean testosterone levels increased but remained in the normal range for all treatment groups. Dutasteride appeared to be well tolerated with an adverse event profile similar to placebo.

The proximity between helix I and helix XI in the melibiose carrier of Escherichia coli as determined by cross-linking

The melibiose carrier of Escherichia coli is a transmembrane protein that comprises 12 transmembrane helices connected by periplasmic and cytoplasmic loops, with both the N- and C-termini located on the cytoplasmic side. Our previous studies of second-site revertants suggested proximity between several helices, including helices XI and I. In this study, we constructed six double cysteine mutants, each having one cysteine in helix I and the other in helix XI: three mutants, K18C/S380C, D19C/S380C, and F20C/S380C, have their cysteine pairs near the cytoplasmic side of the carrier, and the other three, T34C/G395C, D35C/G395C, and V36C/G395C, have their cysteine pairs near the periplasmic side. In the absence of substrate, disulfide formations catalyzed by iodine and copper-(1,10-phenanthroline)(3) indicate that helix I and helix XI are in immediate proximity to each other on the periplasmic side but not on the cytoplasmic side, as shown by protease cleavage analyses. We infer that the two helices are tilted with respect to each other, with the periplasmic sides in close proximity.

Cysteine substitutions for individual residues in helix VI of the melibiose carrier of Escherichia coli

The melibiose carrier of Escherichia coli is a cytoplasmic membrane protein that mediates the cotransport of galactosides with H(+), Na(+), or Li(+). In this study we used cysteine-scanning mutagenesis to try to gain information about the position of transmembrane helix VI in the three-dimensional structure of the melibiose carrier. We constructed 23 individual cysteine substitutions in helix VI and an adjacent loop of the carrier. The resulting melibiose carriers retained 22-100% of their ability to transport melibiose. We tested the effect of the hydrophilic sulfhydryl reagent p-chloromercuri-benzenesulfonic acid (PCMBS) on the cysteine-substitution mutants and we found that there was no inhibition of melibiose transport in any of the mutants. We suggest that helix VI is imbedded in phospholipid and does not face the aqueous channel through which melibiose passes.

The effect of modifications of the charged residues in the transmembrane helices on the transport activity of the melibiose carrier of Escherichia coli

The melibiose transport carrier of Escherichia coli (coded by melB gene) is a cotransport system which couples the transport of a-galactosides to protons, sodium, or lithium ions. The charged amino acid residues in membrane-spanning helices are of considerable interest because many of them have important function in substrate recognition. In most cases changing these charged residue to an uncharged residue (cysteine) results in total loss of activity. In this communication we describe experiments in which the cysteine substitution for a charged residue was chemically changed by sulfhydryl reagents (MTSEA and MTSET to restore a positive charge and MTSES a negative charge) or by iodoacetic acid or through oxidation by hydrogen peroxide so as to regain the original negative charge. In two cases (D55C and D124C) the reconstructed negative charges via the oxidation of the thiol to the sulfinic and/or sulfonic acid resulted in partial recovery of transport: D55C up to 27% of the normal and D124C up to 4% of the normal in melibiose accumulation; D55C up to 36% of the normal and D124 up to 4.5% of the normal in downhill transport. Sulfhydryl reagents and iodoacetic acid failed to recover transport in all cases. We infer that the configurations of the charges as well as the structure of the side chains that carry them are critical in the maintenance of the transport.

Regulation of galactoside transport by the PTS

Inducer exclusion, regulation of activity of transporter, is mediated by phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). To elucidate the molecular mechanism of the inducer exclusion, numerous biochemical and genetic studies have been performed. It is now well known that non-phosphorylated IIA(Glc) inhibits the transport via direct binding to the transporter. Analysis of inducer exclusion resistant mutants of lactose transporter and melibiose transporter in Escherichia coli and Salmonella typhimurium revealed amino acid residues that are involved in the interaction with IIA(Glc). It is concluded that there are multiple interaction sites for IIA(Glc) in these transporters.

Cysteine mutagenesis of the amino acid residues of transmembrane helix I in the melibiose carrier of Escherichia coli

The melibiose carrier of Escherichia coli is a sugar-cation cotransport system that utilizes Na(+), Li(+), or H(+). This membrane transport protein consists of 12 transmembrane helices. Starting with the cysteine-less melibiose carrier, cysteine has been substituted individually for amino acids 17-37, which includes all of the residues in membrane helix I. The carriers with cysteine substitutions were studied for their transport activity and the effect of the water soluble sulfhydryl reagent p-chloro- mercuribenzenesulfonic acid (PCMBS). Cysteine substitution caused loss of transport activity in six of the mutants (G17C, K18C, D19C, Y32C, T34C, and D35C). PCMBS caused greater than 50% inhibition in eleven mutants (F20C, A21C, I22C, G23C, I24C, V25C, Y26C, M27C, Y28C, M30C, and Y31C). We suggest that the residues whose cysteine derivatives were inhibited by PCMBS face the aqueous channel and that helix I is completely surrounded by aqueous environment. Second site revertants were isolated from K18C and Y31C. The revertants were found to have mutations in helices I, IV, and VII.

Sodium-substrate cotransport in bacteria

A variety of sodium-substrate cotransport systems are known in bacteria. Sodium enters the cell down an electrochemical concentration gradient. There is obligatory coupling between the entry of the ion and the entry of substrate with a stoichiometry (in the cases studied) of 1:1. Thus, the downhill movement of sodium ion into the cell leads to the accumulation of substrate within the cell. The melibiose carrier of Escherichia coli is perhaps the most carefully studied of the sodium cotransport systems in bacteria. This carrier is of special interest because it can also use protons or lithium ions for cotransport. Other sodium cotransport carriers that have been studied recently are for proline, glutamate, serine-threonine, citrate and branched chain amino acids.

Physiological evidence for an interaction between helices II and XI in the melibiose carrier of Escherichia coli

The melibiose carrier from Escherichia coli is a cation-substrate cotransporter that catalyzes the accumulation of galactosides at the expense of H(+), Na(+), or Li(+) electrochemical gradients. Charged residues on transmembrane domains in the amino-terminal portion of this carrier play an important role in the recognition of cations, while the carboxyl portion of the protein seems to be important for sugar recognition. In the present study, we substituted Lys-377 on helix XI with Val. This mutant carrier, K377V, had reduced melibiose transport activity. We subsequently used this mutant for the isolation of functional second-site revertants. Revertant strains showed the additional substitutions of Val or Asn for Asp-59 (helix II), or Leu for Phe-20 (helix I). Isolation of revertant strains where both Lys-377 and Asp-59 are substituted with neutral residues suggested the possibility that a salt bridge exists between helix II and helix XI. To further test this idea, we constructed three additional site-directed mutants: Asp-59-->Lys (D59K), Lys-377-->Asp (K377D), and a double mutant, Asp-59-->Lys/Lys-377-->Asp (D59K/K377D), in which the position of these charges was exchanged. K377D accumulated melibiose only marginally while D59K could not accumulate. However, the D59K/K377D double mutant accumulated melibiose to a modest level although this activity was no longer stimulated by Na(+). We suggest that Asp-59 and Lys-377 interact via a salt bridge that brings helix II and helix XI close to one another in the three-dimensional structure of the carrier.

Sugar recognition mutants of the melibiose carrier of Escherichia coli: possible structural information concerning the arrangement of membrane-bound helices and sugar/cation recognition site

Melibiose carrier mutants, isolated by growing cells on melibiose plus the non-metabolizable competitive inhibitor thiomethyl-beta-galactoside (TMG), were studied to determine sugar and cation recognition abnormalities. Most of the mutants show good transport of melibiose but have lost the recognition of TMG. In addition, most mutants show little or no transport of lactose. Cation recognition is also affected as all of these mutants have lost the ability to transport protons with melibiose. The amino acids causing these mutations were determined by sequencing the melB gene on the plasmid. The mutations were located on helices I, IV, VII, X and XI. We propose that these five helices are in proximity with each other and that they line the sugar/cation transport channel.