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.

The effects of combination therapy with dutasteride and tamsulosin on clinical outcomes in men with symptomatic benign prostatic hyperplasia: 4-year results from the CombAT study.

BACKGROUND: Combination therapy with dutasteride and tamsulosin provides significantly greater benefit than either monotherapy for various patient-reported outcomes in men with moderate-to-severe lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH) and prostatic enlargement. OBJECTIVE: To investigate whether combination therapy is more effective than either monotherapy in reducing the relative risk for acute urinary retention (AUR), BPH-related surgery, and BPH clinical progression over 4 yr in men at increased risk of progression. DESIGN, SETTING, AND PARTICIPANTS: The Combination of Avodart and Tamsulosin (CombAT) study was a 4-yr, multicenter, randomised, double-blind, parallel-group study in 4844 men > or =50 yr of age with a clinical diagnosis of BPH, International Prostate Symptom Score > or =12, prostate volume > or =30 cm(3), prostate-specific antigen 1.5-10 ng/ml, and maximum urinary flow rate (Q(max)) >5 and < or =15 ml/s with minimum voided volume > or =125 ml. INTERVENTION: Oral daily tamsulosin, 0.4 mg; dutasteride, 0.5 mg; or a combination of both. MEASUREMENTS: The 4-yr primary end point was time to first AUR or BPH-related surgery. Secondary end points included BPH clinical progression, symptoms, Q(max), prostate volume, safety, and tolerability. RESULTS AND LIMITATIONS: Combination therapy was significantly superior to tamsulosin monotherapy but not dutasteride monotherapy at reducing the relative risk of AUR or BPH-related surgery. Combination therapy was also significantly superior to both monotherapies at reducing the relative risk of BPH clinical progression. Combination therapy provided significantly greater symptom benefit than either monotherapy at 4 yr. Safety and tolerability of combination therapy was consistent with previous experience with dutasteride and tamsulosin monotherapies, with the exception of an imbalance in the composite term of cardiac failure among the three study arms. The lack of placebo control is a study limitation. CONCLUSIONS: The 4-yr CombAT data provide support for the long-term use of dutasteride and tamsulosin combination therapy in men with moderate-to-severe LUTS due to BPH and prostatic enlargement. CLINICALTRIALS.GOV IDENTIFIER: NCT00090103 (http://www.clinicaltrials.gov/ct2/show/NCT00090103).

Combination therapy with dutasteride and tamsulosin in men with moderate-to-severe benign prostatic hyperplasia and prostate enlargement: the CombAT (Combination of Avodart and Tamsulosin) trial rationale and study design.

Benign prostatic hyperplasia (BPH) is a highly prevalent condition in aging men, which can be progressive and lead to acute urinary retention (AUR) and the need for surgery. It is commonly treated with alpha-blockers and 5alpha-reductase inhibitors (5ARIs), both of which improve the symptoms of BPH. Long-term treatment with 5ARIs can also reduce the risk of developing AUR and the need for surgery. The landmark Medical Therapy of Prostatic Symptoms (MTOPS) trial demonstrated that over 4 years the combination of the type 2-specific 5ARI, finasteride and the alpha-blocker doxazosin was more effective than either agent alone in reducing overall clinical progression. Since the initiation of MTOPS, it has been shown that patients with larger prostates and higher prostate-specific antigen (PSA) levels are at greater risk of BPH progression, and are therefore arguably more likely to benefit from combination therapy. The Combination of Avodart and Tamsulosin (CombAT) trial is a 4-year, global, multicenter, randomized, double-blind, parallel-group study designed to investigate the benefits of combination therapy with the dual 5ARI dutasteride and the alpha-blocker tamsulosin compared with each monotherapy in improving symptoms and long-term outcomes in men with moderate-to-severe symptoms of BPH and prostate enlargement. Symptoms and long-term outcomes (AUR and surgery) will be assessed as separate primary endpoints at 2 and 4 years, respectively. Eligible patients were at least 50 years old with prostate volume > or =30 cm(3) and PSA level > or =1.5 ng/mL. A total of 4838 subjects have been enrolled. This paper describes the rationale, design and baseline data of the CombAT study.

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.