A Model-Informed Drug Development Approach to Design a Phase 3 Trial of Teverelix Drug Product in Advanced Prostate Cancer Patients with Increased Cardiovascular Risk.

Teverelix drug product (DP) is a parenteral gonadotropin-releasing hormone (GnRH) antagonist that has been successfully tested in phase 2 trials for hormone-sensitive advanced prostate cancer (APC) and benign prostatic hyperplasia (BPH). In previous APC trials, teverelix DP was administered as intramuscular (IM) and subcutaneous (SC) injections, using a loading dose and (in a single trial) a maintenance dose. Our objective was to derive an optimal dosing regimen for phase 3 clinical development, using a pharmacometrics modeling approach. Data from 9 phase 2 studies (229 patients) was utilized to develop a population pharmacokinetic (PK) model that described the concentration profile accommodating both IM and SC routes of administration. A 2-compartment model with sequential first-order absorption (slow and fast) and lag times best described the PK profiles of teverelix following SC and IM administration. An indirect response model with inhibition of production rate was fit to describe testosterone (T) concentrations based on physiological relevance. The final population PK-pharmacodynamic model was used to conduct simulations of various candidate dosing regimens to select the optimal dosing regimen to achieve clinical castration (T < 0.5 ng/mL by day 28) and to sustain clinical castration for 26 weeks. Model simulation showed that a loading dose of 360 mg SC and 180 mg IM with a maintenance dose of 360 mg SC 6-weekly (Q6W) starting at day 28 can achieve a ≥95% castration rate up to 52 weeks. This dose regimen was selected for phase 3 clinical development, which includes cardiovascular safety assessment in comparison to a GnRH agonist.

Efficacy, tolerability, and safety of teverelix DP in patients with advanced prostate cancer: A multicenter, open-label, phase 2 trial.

BACKGROUND: Teverelix drug product (DP) is a novel injectable gonadotropin-releasing hormone antagonist. METHODS: An adaptive phase 2, open-label, multicenter trial was conducted in patients with advanced prostate cancer to evaluate the efficacy and safety of a combined subcutaneous (SC) and intramuscular (IM) loading dose regimen of teverelix DP of 120 mg SC + 120 mg IM (Group 1; N = 9) or 180 mg SC + 180 mg IM (Group 2; N = 41) administered at a single visit, followed by 6-weekly SC maintenance doses of 120 mg (Group 1) or 180 mg (Group 2), up to Day 168. The primary endpoint was the proportion of patients achieving castration levels with serum testosterone <0.5 ng/mL at Day 28 with a target castration rate of 90%. Injection sites were inspected by the investigator at every visit and reactions (ISRs) were proactively recorded. RESULTS: The target castration rate was reached in Group 2 (97.5%) but not in Group 1 (62.5%). The castration rates were not maintained to Day 42 (Group 2: 82.5%; Group 1: 50.0%). Suppression of testosterone to castrate levels occurred rapidly (median time: 2 days for both groups). Suppression of testosterone, prostate-specific antigen, follicle-stimulating hormone, and luteinizing hormone was sustained throughout the treatment period, being more prominent with the higher dose. The adverse event (AE) profile was similar between groups. The most common AEs were injection-site induration (n = 40: 80.0%), injection-site erythema (n = 35: 70.0%), and hot flush (n = 21: 42.0%). Most ISRs were Grade 1. CONCLUSION: Overall, the teverelix DP doses were generally well-tolerated but did not adequately maintain castration levels.

Safety, Pharmacokinetic and Pharmacodynamic Evaluation of Teverelix for the Treatment of Hormone-Sensitive Advanced Prostate Cancer: Phase 2 Loading-Dose-Finding Studies.

Background and objectives: Teverelix drug product (DP) is a gonadotropin-releasing hormone antagonist in development for the treatment of patients with prostate cancer in whom androgen deprivation therapy is indicated. The aim of this paper is to present the results of five Phase 2 studies that assessed the pharmacokinetics, pharmacodynamics, efficacy and safety of different loading dose regimens of teverelix DP. Methods: Five single-arm, uncontrolled clinical trials were conducted in patients with advanced prostate cancer. The five different loading dose regimens of teverelix DP tested were (a) a single 90 mg subcutaneous (SC) injection of teverelix DP given on 3 consecutive days (Days 0, 1 and 2); (b) a single 90 mg intramuscular (IM) injection of teverelix DP given 7 days apart (Days 0 and 7); (c) a single 120 mg SC injection of teverelix DP given on 2 consecutive days (Days 0 and 1); (d) 2 × 60 mg SC injections of teverelix DP given on 3 consecutive days (Days 0, 1 and 2), and (e) 2 × 90 mg SC injections of teverelix DP given on 3 consecutive days (Days 0, 1 and 2). The primary efficacy parameter was the duration of action of an initial loading dose regimen in terms of suppression of testosterone to below the castration level (0.5 ng/mL). Results: Eighty-two patients were treated with teverelix DP. Two regimens (90 mg and 180 mg SC on 3 consecutive days) had a mean duration of castration of 55.32 days and 68.95 days with >90% of patients having testosterone levels < 0.5 ng/mL at Day 28. The mean onset of castration for the SC regimens ranged from 1.10 to 1.77 days, while it was slower (2.4 days) with IM administration. The most common adverse event (AE) was injection site reaction. No AEs of severe intensity were reported. Conclusions: Teverelix DP is safe and well tolerated. Castrate levels of testosterone can be rapidly achieved following the subcutaneous injection of teverelix DP on 3 consecutive days. Streamlining of the administration of the loading dose and identifying a suitable maintenance dose will be investigated in future trials.

Five-year Survival Prediction and Safety Outcomes with Enzalutamide in Men with Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer from the PREVAIL Trial.

BACKGROUND: In the PREVAIL study, enzalutamide significantly improved clinical outcomes versus placebo in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC). OBJECTIVE: To evaluate long-term benefits and risks of enzalutamide in the final prespecified PREVAIL analysis. DESIGN, SETTING, AND PARTICIPANTS: We conducted a final 5-yr survival analysis of PREVAIL in men with chemotherapy-naïve mCRPC from the enzalutamide (n = 689) and placebo (n = 693) arms. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Predictors of the primary outcome of overall survival were estimated using the Kaplan-Meier method. Long-term adverse events over time were analyzed. RESULTS AND LIMITATIONS: At the 5-yr data cutoff, 1382 of 1717 (80%) men had died. Enzalutamide reduced the hazard of death by 17% (hazard ratio 0.83; 95% confidence interval [CI] 0.75-0.93; p < 0.001), despite 65%, 54%, and 43% of placebo-treated patients receiving subsequent docetaxel, abiraterone, and enzalutamide, respectively. Median overall survival was 36 mo (95% CI 34-38) in the enzalutamide arm versus 31 mo (95% CI 29-34) in the placebo arm, with a median follow-up of 69 mo. Prognostic modeling showed 5-yr survival rates of 42%, 24%, and 5% for low-, intermediate-, and high-risk groups, respectively. Greater degrees of confirmed prostate-specific antigen declines (≤3 mo) were associated with greater 5-yr survival. A higher incidence of fatal treatment-emergent adverse events was observed with enzalutamide (6.9% vs 3.8%), with an increase in fatal cardiovascular events (1.6% vs 0.4%). CONCLUSIONS: With >5 yr of follow-up, enzalutamide continued to demonstrate improved survival in patients with mCRPC despite crossover and multiple subsequent effective therapies, balanced against a slightly higher rate of fatal cardiovascular events. PREVAIL is registered on ClinicalTrials.gov as NCT01212991. PATIENT SUMMARY: We report a maintained long-term survival benefit with enzalutamide and risks with >5 yr of enzalutamide treatment and follow-up in men with metastatic prostate cancer, and identify groups of men with widely different outcomes based on clinical factors.

Efficacy and Safety of Enzalutamide vs Bicalutamide in Younger and Older Patients with Metastatic Castration Resistant Prostate Cancer in the TERRAIN Trial.

PURPOSE: Enzalutamide significantly prolonged median progression-free survival vs bicalutamide in chemotherapy naïve men with metastatic castration resistant prostate cancer in the TERRAIN (Enzalutamide versus Bicalutamide in Castrate Men with Metastatic Prostate Cancer) trial. In this post hoc analysis we investigated the influence of age on the efficacy and safety of enzalutamide vs bicalutamide in this population. MATERIALS AND METHODS: Patients were randomized 1:1 to enzalutamide 160 mg per day or bicalutamide 50 mg per day. Progression-free survival, time to prostate specific antigen progression and safety were analyzed post hoc in younger (age less than 75 years) and older (age 75 years or greater) subgroups. RESULTS: Enzalutamide significantly reduced the risk of disease progression or death vs bicalutamide in patients younger than 75 years (HR 0.38, 95% CI 0.27-0.52, p <0.0001) and 75 years old or older (HR 0.59, 95% CI 0.37-0.92, p = 0.018). Time to prostate specific antigen progression was also significantly prolonged with enzalutamide vs bicalutamide in each subgroup. The adverse event distribution between treatments was similar in each subgroup except for more (5% or greater difference between subgroups) atrial fibrillation, urinary tract infections, falls and decreased appetite as well as less extremity pain and hot flushing in enzalutamide treated patients 75 years old or older, and less back pain and hot flushing in bicalutamide treated patients 75 years old or older. Grade 3 or greater cardiac events were more frequent in enzalutamide treated and bicalutamide treated patients who were 75 years old or older vs younger than 75 years. Fatigue was more frequent in enzalutamide treated patients with a similar distribution in each age subgroup. CONCLUSIONS: Enzalutamide improved clinical outcomes vs bicalutamide irrespective of age. Increased falls and cardiac events suggest caution when prescribing to older patients (age 75 years or greater) with significant comorbidity.

Enzalutamide in Men with Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer: Extended Analysis of the Phase 3 PREVAIL Study.

Enzalutamide significantly improved radiographic progression-free survival (rPFS) and overall survival (OS) among men with chemotherapy-naïve metastatic castration-resistant prostate cancer at the prespecified interim analysis of PREVAIL, a phase 3, double-blind, randomized study. We evaluated the longer-term efficacy and safety of enzalutamide up to the prespecified number of deaths in the final analysis, which included an additional 20 mo of follow-up for investigator-assessed rPFS, 9 mo of follow-up for OS, and 4 mo of follow-up for safety. Enzalutamide reduced the risk of radiographic progression or death by 68% (hazard ratio [HR] 0.32, 95% confidence interval [CI] 0.28-0.37; p<0.0001) and the risk of death by 23% (HR 0.77, 95% CI 0.67-0.88; p=0.0002). Median investigator-assessed rPFS was 20.0 mo (95% CI 18.9-22.1) in the enzalutamide arm and 5.4 mo (95% CI 4.1-5.6) in the placebo arm. Median OS was 35.3 mo (95% CI 32.2-not yet reached) in the enzalutamide arm and 31.3 mo (95% CI 28.8-34.2) in the placebo arm. At the time of the OS analysis, 167 patients in the placebo arm had crossed over to receive enzalutamide. The most common adverse events in the enzalutamide arm were fatigue, back pain, constipation, and arthralgia. This final analysis of PREVAIL provides more complete assessment of the clinical benefit of enzalutamide. PREVAIL is registered on ClinicalTrials.gov as NCT01212991. PATIENT SUMMARY: According to data from longer follow-up, enzalutamide continued to provide benefit over placebo in patients with metastatic castration-resistant prostate cancer.

Efficacy and safety of enzalutamide versus bicalutamide for patients with metastatic prostate cancer (TERRAIN): a randomised, double-blind, phase 2 study.

BACKGROUND: Enzalutamide is an oral androgen-receptor inhibitor that has been shown to improve survival in two placebo-controlled phase 3 trials, and is approved for patients with metastatic castration-resistant prostate cancer. The objective of the TERRAIN study was to compare the efficacy and safety of enzalutamide with bicalutamide in patients with metastatic castration-resistant prostate cancer. METHODS: TERRAIN was a double-blind, randomised phase 2 study, that recruited asymptomatic or minimally symptomatic men with prostate cancer progression on androgen-deprivation therapy (ADT) from academic, community, and private health-care provision sites across North America and Europe. Eligible patients were randomly assigned (1:1) via an interactive voice response system to receive enzalutamide 160 mg/day or bicalutamide 50 mg/day, both taken orally, in addition to ADT, until disease progression. Patients were stratified by a permutated block method (block size of four), by whether bilateral orchiectomy or receipt of luteinising hormone-releasing hormone agonist or antagonist therapy started before or after the diagnosis of metastases, and by study site. Participants, investigators, and those assessing outcomes were masked to group assignment. The primary endpoint was progression-free survival, analysed in all randomised patients. Safety outcomes were analysed in all patients who received at least one dose of study drug. The open-label period of the trial is in progress, wherein patients still on treatment at the end of the double-blind treatment period were offered open-label enzalutamide at the discretion of the patient and study investigator. This trial is registered with ClinicalTrials.gov, number NCT01288911. FINDINGS: Between March 22, 2011, and July 11, 2013, 375 patients were randomly assigned, 184 to enzalutamide and 191 to bicalutamide. 126 (68%) and 168 (88%) patients, respectively, discontinued their assigned treatment before study end, mainly due to progressive disease. Median follow-up time was 20·0 months (IQR 15·0-25·6) in the enzalutamide group and 16·7 months (10·2-21·9) in the bicalutamide group. Patients in the enzalutamide group had significantly improved median progression-free survival (15·7 months [95% CI 11·5-19·4]) compared with patients in the bicalutamide group (5·8 months [4·8-8·1]; hazard ratio 0·44 [95% CI 0·34-0·57]; p<0·0001). Of the most common adverse events, those occurring more frequently with enzalutamide than with bicalutamide were fatigue (51 [28%] of 183 patients in the enzalutamide group vs 38 [20%] of 189 in the bicalutamide group), back pain (35 [19%] vs 34 [18%]), and hot flush (27 [15%] vs 21 [11%]); those occurring more frequently with bicalutamide were nausea (26 [14%] vs 33 [17%]), constipation (23 [13%] vs 25 [13%]), and arthralgia (18 [10%] vs 30 [16%]). The most common grade 3 or worse adverse events in the enzalutamide or bicalutamide treatment groups, respectively, were hypertension (13 [7%] vs eight [4%]), hydronephrosis (three [2%] vs seven [4%]), back pain (five [3%] vs three [2%]), pathological fracture (five [3%] vs two [1%]), dyspnoea (four [2%] vs one [1%]), bone pain (one [1%] vs four [2%]), congestive cardiac failure (four [2%] vs two [1%]), myocardial infarction (five [3%] vs none), and anaemia (four [2%] vs none]). Serious adverse events were reported by 57 (31%) of 183 patients and 44 (23%) of 189 patients in the enzalutamide and bicalutamide groups, respectively. One of the nine deaths in the enzalutamide group was thought to be possibly related to treatment (due to systemic inflammatory response syndrome) compared with none of the three deaths in the bicalutamide group. INTERPRETATION: The data from the TERRAIN trial support the use of enzalutamide rather than bicalutamide in patients with asymptomatic or mildly symptomatic metastatic castration-resistant prostate cancer. FUNDING: Astellas Pharma, Inc and Medivation, Inc.

Development of enzalutamide for metastatic castration-resistant prostate cancer.

Prostate cancer is the most prevalent cancer among men in the Western world and a leading cause of cancer-related death among men. Within 5 years of initial diagnosis, approximately 10-20% of men will progress to metastatic castration-resistant prostate cancer (mCRPC). Often characterized by increased prostate-specific antigen and androgen receptor (AR) activity despite castrate levels of testosterone, mCRPC has a poor prognosis and causes significant deterioration in quality of life. Enzalutamide is an AR inhibitor approved to treat mCRPC in both post- and pre-chemotherapy settings on the basis of results from two phase III randomized, placebo-controlled trials, AFFIRM and PREVAIL, respectively. Enzalutamide significantly prolonged overall survival (hazard ratio (HR), AFFIRM 0.63, 95% confidence interval (CI) 0.53-0.75, P < 0.001; PREVAIL 0.71, 95% CI 0.60-0.84, P < 0.001) and radiographic progression (HR, AFFIRM 0.40, 95% CI 0.35-0.47, P < 0.001; PREVAIL 0.19, 95% CI 0.15-0.23, P < 0.001), and significantly improved quality of life. With an acceptable safety profile, enzalutamide is one of several emerging alternative options for men with mCRPC. Studies are ongoing to explore potential benefits of enzalutamide in earlier stages of prostate cancer and in breast cancer.

Low-dose tibolone (1.25 mg/d) does not affect muscle strength in older women.

OBJECTIVE: More than 50% of all fractures occur in people without osteoporosis. Hormone therapy increases bone density, improves postural balance, and reduces fracture risk in postmenopausal women. It is unclear whether tibolone, a synthetic steroid hormone drug, can improve muscle strength. Thus, the aim of this study was to study the effects of low-dose tibolone therapy on muscle strength in older women. METHODS: Eighty healthy women (69 completed the study) 60 years or older were recruited through advertising in the local media. They were randomly allocated to receive either tibolone 1.25 mg/day or placebo for 6 months. The stand-up test was used to assess leg muscle strength and balance. Handgrip and leg muscle strength were measured using JAMAR and modified Cybex dynamometers. RESULTS: Baseline characteristics, including serum estradiol values and muscle strength, were similar in the two groups. Compliance with the therapy regimen was very high, averaging more than 97% in both groups. After 6 months, mean values for handgrip strength, knee extensor strength, and average time to perform 10 stands were improved numerically in both groups compared with values during baseline. However, there were no significant differences in these parameters within or between groups, and differences remained nonsignificant after adjustment for age, serum estradiol, and baseline value. CONCLUSIONS: Short-term treatment with low-dose tibolone (1.25 mg/d) seems not to affect muscle strength in older women.

Safety and efficacy of tibolone in breast-cancer patients with vasomotor symptoms: a double-blind, randomised, non-inferiority trial.

BACKGROUND: Vasomotor symptoms and bone loss are complications frequently induced by adjuvant treatment for breast cancer. Tibolone prevents both side-effects, but its effect on cancer recurrence is unknown. The aim of this study was to show non-inferiority of tibolone to placebo regarding risk of recurrence in breast-cancer patients with climacteric complaints. METHODS: Between July 11, 2002, and Dec 20, 2004, women surgically treated for a histologically confirmed breast cancer (T(1-3)N(0-2)M(0)) with vasomotor symptoms were randomly assigned to either tibolone 2.5 mg daily or placebo at 245 centres in 31 countries. Randomisation was done by use of a centralised interactive voice response system, stratified by centre, with a block size of four. The primary endpoint was breast-cancer recurrence, including contralateral breast cancer, and was analysed in the intention-to-treat (ITT) and per-protocol populations; the margin for non-inferiority was set as a hazard ratio of 1.278. This study is registered with ClinicalTrials.gov, number NCT00408863. FINDINGS: Of the 3148 women randomised, 3098 were included in the ITT analysis (1556 in the tibolone group and 1542 in the placebo group). Mean age at randomisation was 52.7 years (SD 7.3) and mean time since surgery was 2.1 years (SD 1.3). 1792 of 3098 (58%) women were node positive and 2185 of 3098 (71%) were oestrogen-receptor positive. At study entry, 2068 of 3098 (67%) women used tamoxifen and 202 of 3098 (6.5%) women used aromatase inhibitors. The mean daily number of hot flushes was 6.4 (SD 5.1). After a median follow-up of 3.1 years (range 0.01-4.99), 237 of 1556 (15.2%) women on tibolone had a cancer recurrence, compared with 165 of 1542 (10.7%) on placebo (HR 1.40 [95% CI 1.14-1.70]; p=0.001). Results in the per-protocol population were similar (209 of 1254 [16.7%] women in the tibolone group had a recurrence vs 138 of 1213 [11.4%] women in the placebo group; HR 1.44 [95% CI 1.16-1.79]; p=0.0009). Tibolone was not different from placebo with regard to other safety outcomes, such as mortality (72 patients vs 63 patients, respectively), cardiovascular events (14 vs 10, respectively), or gynaecological cancers (10 vs 10, respectively). Vasomotor symptoms and bone-mineral density improved significantly with tibolone, compared with placebo. INTERPRETATION: Tibolone increases the risk of recurrence in breast cancer patients, while relieving vasomotor symptoms and preventing bone loss. FUNDING: Schering-Plough (formerly NV Organon, Oss, Netherlands).

Tibolone low dose (1.25 mg/d) therapy and postural balance in elderly women.

UNLABELLED: Most hip fractures occur in subjects without osteoporosis and are associated with a fall. Conventional menopausal hormone therapy (HT) improves postural balance, which might explain the rapid reduction in hip fracture risk. It is unclear whether tibolone improves postural balance, which might determine its effects on peripheral fracture risk. OBJECTIVE: To study the short-term effects of low-dose tibolone therapy on postural balance in elderly women. METHODS: Eighty healthy women (70 evaluable), aged 60 years or more, were recruited through advertising in the local media. They were randomly allocated to receive either tibolone (1.25 mg/d) or placebo for 6 months. Postural balance was assessed as sway velocity, using a force platform. RESULT(S): Baseline characteristics, including serum estradiol values and postural balance, were similar in the two study groups. On average, the overall dosing compliance was very high, over 97% in both groups. After 6 months, sway velocity had decreased (improved) by 7.6% (-0.97 cm/s; P=0.16 vs. baseline) in the tibolone arm and by 2.5% (-0.30 cm/s; P=0.59 vs. baseline) in the placebo group. The difference 0.67 cm/s was not statistically significant (95% CI -2.44, 1.10; P=0.45). Adjustments for age, serum estradiol level and variable value at baseline, revealed similar results. CONCLUSIONS: Short-term treatment with tibolone (1.25 mg/d), compared to placebo, did not significantly affect postural balance function in elderly women.

Endometrial effects of tibolone in elderly, osteoporotic women.

OBJECTIVE: To investigate endometrial effects of tibolone administered to postmenopausal women for 3 years. METHODS: Postmenopausal women (N=3,519) aged 60-85 years (mean 68 years) with a uterus and with osteoporosis were randomly assigned to receive tibolone orally, 1.25 mg per day, or identical placebo. We evaluated effects on endometrial thickness in all women, and examined endometrial histology in 635 participants considered to be at increased risk for abnormalities (with unexpected vaginal bleeding or endometrial thickness more than 4 mm). RESULTS: During the first year of study, mean endometrial thickness increased 1 mm in women receiving tibolone (P<.001), but no further increases were noted during the next 2 years. Diagnostic biopsies among 499 women receiving tibolone and 136 who were receiving placebo showed cumulative incidences of endometrial hyperplasia less than 1%. Among the 15% of women whose biopsy showed an endometrial polyp (similar rate in tibolone and placebo), those receiving tibolone were more than twice as likely to show hyperplasia within the polyp. A marginal increase in grade 1 endometrioid adenocarcinoma (P=.06 compared with placebo) was found among women receiving tibolone. Prevalences of vaginal bleeding during the study were 10.8% in the tibolone group and 2.8% in the placebo group (P<.001). CONCLUSION: Tibolone treatment during 3 years minimally increased endometrial thickness, hyperplastic polyps, endometrial carcinoma, and vaginal bleeding.