Mohammad Hirmand

Antitumour activity of MDV3100 in castration-resistant prostate cancer: a phase 1–2 study

BACKGROUND MDV3100 is an androgen-receptor antagonist that blocks androgens from binding to the androgen receptor and prevents nuclear translocation and co-activator recruitment of the ligand-receptor complex. It also induces tumour cell apoptosis, and has no agonist activity. Because growth of castration-resistant prostate cancer is dependent on continued androgen-receptor signalling, we assessed the antitumour activity and safety of MDV3100 in men with this disease. METHODS This phase 1-2 study was undertaken in five US centres in 140 patients. Patients with progressive, metastatic, castration-resistant prostate cancer were enrolled in dose-escalation cohorts of three to six patients and given an oral daily starting dose of MDV3100 30 mg. The final daily doses studied were 30 mg (n=3), 60 mg (27), 150 mg (28), 240 mg (29), 360 mg (28), 480 mg (22), and 600 mg (3). The primary objective was to identify the safety and tolerability profile of MDV3100 and to establish the maximum tolerated dose. The trial is registered with ClinicalTrials.gov, number NCT00510718. FINDINGS We noted antitumour effects at all doses, including decreases in serum prostate-specific antigen of 50% or more in 78 (56%) patients, responses in soft tissue in 13 (22%) of 59 patients, stabilised bone disease in 61 (56%) of 109 patients, and conversion from unfavourable to favourable circulating tumour cell counts in 25 (49%) of the 51 patients. PET imaging of 22 patients to assess androgen-receptor blockade showed decreased (18)F-fluoro-5alpha-dihydrotestosterone binding at doses from 60 mg to 480 mg per day (range 20-100%). The median time to progression was 47 weeks (95% CI 34-not reached) for radiological progression. The maximum tolerated dose for sustained treatment (>28 days) was 240 mg. The most common grade 3-4 adverse event was dose-dependent fatigue (16 [11%] patients), which generally resolved after dose reduction. INTERPRETATION We recorded encouraging antitumour activity with MDV3100 in patients with castration-resistant prostate cancer. The results of this phase 1-2 trial validate in man preclinical studies implicating sustained androgen-receptor signalling as a driver in this disease. FUNDING Medivation, the Prostate Cancer Foundation, National Cancer Institute, the Howard Hughes Medical Institute, Doris Duke Charitable Foundation, and Department of Defense Prostate Cancer Clinical Trials Consortium.

Effect of MDV3100, an androgen receptor signaling inhibitor (ARSI), on overall survival in patients with prostate cancer postdocetaxel: Results from the phase III AFFIRM study.

LBA1 Background: MDV3100, a novel androgen receptor signaling inhibitor (ARSI), competitively inhibits binding of androgens to the androgen receptor (AR), inhibits AR nuclear translocation, and inhibits association of the AR with DNA (Tran et al, Science. 2009;324:787). MDV3100 was selected for development based on activity in prostate cancer model systems with overexpressed AR, and was active in a phase I-II trial enrolling pre- and post-chemotherapy treated patients with progressive castration resistant disease (CRPC) (Scher et al, Lancet. 2010;375:1437). The AFFIRM trial evaluated whether MDV3100 could prolong overall survival (OS) in men with CRPC who progressed following docetaxel-based chemotherapy. METHODS In this randomized, double-blind, placebo-controlled, multinational phase III study ( NCT00974311 ), patients who had received ≤ 2 regimens of docetaxel-based chemotherapy were randomized 2:1 to MDV3100 160 mg/day or placebo. Treatment with corticosteroids was allowed but not required. Patients were stratified by baseline ECOG performance status and mean brief pain inventory score. The primary endpoint was OS. Other efficacy endpoints included radiographic progression-free survival (PFS), time to first skeletal-related event, time to prostate-specific antigen (PSA) progression, and circulating tumor cell count conversion rate. RESULTS 1,199 patients were randomized between Sep 2009 and Nov 2010. Based on a planned interim analysis at 520 death events, the Independent Data Monitoring Committee (IDMC) recommended the study be unblinded and placebo patients offered MDV3100 due to a significant OS benefit (p<0.0001; hazard ratio 0.631). The estimated median OS was 18.4 months for MDV3100 treated compared to 13.6 months for placebo treated men, a median OS difference of 4.8 months. Data to be available include PFS, time to PSA progression, and safety. CONCLUSIONS MDV3100, a novel ARSI, significantly improves OS in men with postdocetaxel-treated CRPC reducing the risk of death by 37% relative to placebo. The IDMC determined the risk:benefit of MDV3100 was favorable and recommended the phase III AFFIRM trial be unblinded.

Effect of enzalutamide on time to first skeletal-related event, pain, and quality of life in men with castration-resistant prostate cancer: results from the randomised, phase 3 AFFIRM trial

BACKGROUND In the AFFIRM trial of patients with metastatic castration-resistant prostate cancer after progression with docetaxel treatment, enzalutamide significantly increased overall survival compared with placebo. Here we present the prospectively defined analyses of some secondary endpoints, including occurrence of skeletal-related events, measures of pain control, and patient-reported health-related quality of life (HRQoL). METHODS In this phase 3, double-blind trial, patients were randomly assigned (2:1) to receive enzalutamide 160 mg/day or placebo orally, stratified by ECOG baseline performance status (0 or 1 vs 2) and mean pain score (Brief Pain Inventory-Short Form [BPI-SF] question 3 worst pain, score ≤3 vs ≥4). Secondary endpoints were time to first skeletal-related event (defined as radiation therapy or surgery to bone); change from baseline to week 13 in pain severity and interference; pain palliation and progression at week 13; time to pain progression; overall improvement in HRQoL; improvements in HRQoL domains; and time to HRQoL deterioration. Analysis was done on the intention-to-treat population for each endpoint. AFFIRM is registered with ClinicalTrials.gov, number NCT00974311. FINDINGS Median time to first skeletal-related event in the enzalutamide (n=800) and placebo (n=399) groups was 16·7 months (95% CI 14·6 to 19·1) and 13·3 months (95% CI 9·9 to not yet reached), respectively (hazard ratio [HR] 0·69 [95% CI 0·57-0·84]; p=0·0001). Pain progression at week 13 occurred in 174 (28%) of 625 evaluable patients in the enzalutamide group versus 101 (39%) of 259 patients in the placebo group (difference -11·2%, 95% CI -18·1 to -4·3; p=0·0018). Median time to pain progression was not yet reached in the enzalutamide group (95% CI not yet reached to not yet reached) versus 13·8 (13·8 to not yet reached) months in the placebo group (HR 0·56 [95% CI 0·41 to 0·78]; p=0·0004). Mean treatment effects for pain severity (mean change from baseline in the enzalutamide group -0·15, 95% CI -0·28 to -0·02, vs placebo 0·50, 0·29 to 0·70; difference -0·65, 95% CI -0·89 to -0·41; p<0·0001) and interference (-0·01, -0·18 to 0·16, vs 0·74, 0·47 to 1·00; respectively, difference -0·74, 95% -1·06 to -0·43; p<0·0001) were significantly better with enzalutamide than with placebo. 22 (45%) of 49 evaluable patients in the enzalutamide group reported pain palliation at week 13 versus one (7%) of 15 in the placebo group (difference 38·2%, 95% CI 19·4-57·0; p=0·0079). Overall improvement in HRQoL was reported in more patients receiving enzalutamide (275 [42%] of 652) than in those receiving placebo (36 [15%] of 248; p<0·0001). Patients in the enzalutamide group had longer median time to HRQoL deterioration than did those in the placebo group (9·0 months, 95% CI 8·3-11·1, vs 3·7 months, 95% CI 3·0-4·2; HR 0·45, 95% CI 0·37-0·55; p<0·0001) in risk of deterioration. INTERPRETATION Our results show that, in addition to improving overall survival, enzalutamide improves wellbeing and everyday functioning of patients with metastatic castration-resistant prostate cancer. FUNDING Astellas Pharma and Medivation.

Enzalutamide monotherapy in hormone-naive prostate cancer: primary analysis of an open-label, single-arm, phase 2 study

BACKGROUND The androgen receptor inhibitor enzalutamide is approved for the treatment of metastatic castration-resistant prostate cancer that has progressed on docetaxel. Our aim was to assess the activity and safety of enzalutamide monotherapy in men with hormone-naive prostate cancer. METHODS This trial is an ongoing open-label, single-arm, phase 2 study, done across 12 European sites. Men aged over 18 years, with hormone-naive prostate cancer for whom hormone therapy was indicated, and who had non-castration levels of testosterone and prostate-specific antigen (PSA) of 2 ng/mL or greater at screening, and an Eastern Cooperative Oncology Group score of 0, received oral enzalutamide 160 mg/day. The primary outcome was the proportion of patients with an 80% or greater decline in PSA at week 25. All analyses included all patients who had received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT01302041. FINDINGS 67 men were enrolled into the study. 62 patients (92.5%, 95% CI 86.2-98.8) had a decline in PSA of 80% or greater at week 25. The most commonly reported treatment-emergent adverse events up to week 25 were gynaecomastia (n=24), fatigue (n=23), nipple pain (n=13), and hot flush (n=12), all of which were of mild to moderate severity. Nine patients had a treatment-emergent adverse event of grade 3 or higher, most of which were reported in one patient each, except for pneumonia (grade 3, two patients) and hypertension (grade 3, four patients). Five patients reported serious adverse events, none of which were deemed to be treatment related. INTERPRETATION Our findings suggest that enzalutamide monotherapy in men with hormone-naive prostate cancer of varying severity provides a level of disease suppression, and was generally well tolerated. These findings provide a rationale for further investigation of clinical response and outcomes with enzalutamide in non-castrate men with prostate cancer.

Impact of on-study corticosteroid use on efficacy and safety in the phase III AFFIRM study of enzalutamide (ENZA), an androgen receptor inhibitor.

6 Background: ENZA increased median overall survival (OS) by 4.8 mo (P <0.001, HR 0.63) vs placebo (PBO) in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) post-docetaxel in AFFIRM (HI Scher et al, NEJM 2012). Corticosteroids (CS) can activate AR signaling in nonclinical models (J Richards, Can Res 2012). In a multivariate model of AFFIRM data baseline CS use was associated with reduced OS (HI Scher et al. ESMO 2012 abstract 899PD). The impact of CS use during study treatment in AFFIRM was evaluated to test if concomitant CS use is also associated with inferior outcomes. METHODS Pts were randomized 2:1 to ENZA 160 mg/d or PBO. Pts were allowed but not required to take CS. OS was the primary endpoint. In a post-hoc analysis On-study CS use was defined as oral CS user for ≥ 1 day on study. RESULTS On study CS use was 48% in ENZA and 45% in PBO pts. Prognostic factors were slightly better in the no CS group compared to the CS group. Use of CS regardless of treatment was associated median OS of 11.5 mo (95% CI: 10.5, 13.0) for CS pts vs median OS NM (NM, NM) for no CS pts (HR=0.40; 95% CI: 0.33, 0.48). ENZA was consistently superior to PBO for OS, radiographic progression free survival (rPFS) and time to PSA progression (TTPP), regardless of CS use (Table). Pts on CS had higher rates of grade 3 - 4 adverse events (AE) compared to no CS pts: 63.3% vs 34.4% respectively. CONCLUSIONS In this post-hoc analysis, on study CS use was associated with reduced OS and higher rates of grade 3 -4 AEs in mCRPC pts post-docetaxel. While CS pts had worse outcomes, ENZA was consistently superior to PBO regardless of on study CS use. The inferior outcomes in CS pts may be due to unmeasured confounders or the biologic properties of CS use itself. CLINICAL TRIAL INFORMATION NCT00974311. [Table: see text].

Efficacy Outcomes by Baseline Prostate-specific Antigen Quartile in the AFFIRM Trial

BACKGROUND Enzalutamide significantly prolonged the survival of men with metastatic castration-resistant prostate cancer (PCa) after docetaxel in the randomised, phase 3, double-blind, placebo-controlled, multinational Patients with Progressive Castration-Resistant Prostate Cancer Previously Treated with Docetaxel-Based Chemotherapy (AFFIRM) trial (NCT00974311). Prostate-specific antigen (PSA) is commonly used as a marker of PCa disease burden, and the relationship of baseline PSA level to consequent treatment effect is of clinical interest. OBJECTIVE Exploratory analysis to evaluate any differences in patient characteristics and efficacy outcomes by baseline PSA level in the AFFIRM trial. DESIGN, SETTING, AND PARTICIPANTS Post hoc subanalysis of all randomised patients (n=1199) from the AFFIRM trial. INTERVENTION Participants were randomly assigned in a two-to-one ratio to receive oral enzalutamide 160 mg/d or placebo. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The major clinical efficacy end points were overall survival (OS), radiographic progression-free survival (rPFS), and time to PSA progression (TTPP) versus placebo; baseline characteristics, treatment duration, and subsequent antineoplastic therapy were compared by baseline PSA quartile. RESULTS AND LIMITATIONS Baseline PSA quartiles corresponded to the following PSA groups: <40 ng/ml (n=299), 40 to <111 ng/ml (n=300), 111 to <406 ng/ml (n=300), and ≥406 ng/ml (n=300). Enzalutamide consistently improved OS, rPFS, and TTPP compared with placebo across all subgroups, regardless of baseline PSA level. Hazard ratios for improvements in OS were 0.55 (95% confidence interval [CI], 0.36-0.85), 0.69 (95% CI, 0.47-1.02), 0.73 (95% CI, 0.53-1.01), and 0.53 (95% CI, 0.39-0.73) for PSA groups 1-4, respectively. The post hoc design of this analysis was not statistically powered to assess the relationship between baseline PSA and clinical efficacy outcomes. CONCLUSIONS This post hoc analysis of the AFFIRM trial demonstrates consistent benefits in OS, rPFS, and TTPP with enzalutamide regardless of baseline disease severity, as assessed by PSA. PATIENT SUMMARY Exploratory post hoc analysis of the AFFIRM trial showed that enzalutamide improves overall survival, radiographic progression-free survival, and time to prostate-specific antigen progression compared with placebo regardless of baseline disease severity, as assessed by prostate-specific antigen. TRIAL REGISTRATION ClinicalTrials.gov identifier NCT00974311.

Long-term Safety and Antitumor Activity in the Phase 1–2 Study of Enzalutamide in Pre- and Post-docetaxel Castration-Resistant Prostate Cancer

BACKGROUND Given that some patients with castration-resistant prostate cancer (CRPC) have shown extended responses to the androgen receptor inhibitor enzalutamide, long-term safety of this drug is of interest. OBJECTIVE To evaluate the long-term safety and antitumor activity of enzalutamide in CRPC patients. DESIGN, SETTING, AND PARTICIPANTS This phase 1-2 study evaluated enzalutamide in 140 CRPC patients with and without prior chemotherapy. Initial findings were published in 2010. We report updated results from an additional 17-mo follow-up for antitumor activity and >4 yr for safety. INTERVENTION Patients received 30-600mg/d oral enzalutamide. During long-term dosing, all patients were switched first to the maximum tolerated dose of 240mg/d and then to the phase 3 dose of 160mg/d. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Safety was assessed regularly. The Kaplan-Meier method was used to estimate the distributions of time to prostate-specific antigen (PSA) progression and time to radiographic progression. RESULTS AND LIMITATIONS The safety profile of enzalutamide was consistent over time, with little change in the rates of commonly reported adverse events (AEs) or the incidence of grade 3/4 AEs. Fatigue of any grade was the most common dose-dependent AE, experienced by 70% of patients, with 14% of patients reporting grade 3/4 fatigue. The median time to PSA progression was not reached for chemotherapy-naive patients and was 45 wk for postchemotherapy patients; the corresponding median time to radiographic progression was 56 wk and 25 wk. CONCLUSIONS Enzalutamide showed durable antitumor activity in chemotherapy-naive and postchemotherapy patients, and was well tolerated, even in patients treated for 4 yr. PATIENT SUMMARY Enzalutamide was active against prostate cancer and was well tolerated, even for up to 4 yr of treatment, supporting its potential for long-term use in men with prostate cancer. Fatigue was the most common side effect, occurring at varying degrees of severity in most patients.

Long-term Efficacy and Safety of Enzalutamide Monotherapy in Hormone-naïve Prostate Cancer: 1- and 2-Year Open-label Follow-up Results.

BACKGROUND Enzalutamide is an androgen receptor inhibitor with a demonstrated overall survival benefit in metastatic castration-resistant prostate cancer. A phase 2 study of enzalutamide monotherapy in patients with hormone-naïve prostate cancer (HNPC) showed a high response rate for the prespecified primary endpoint (ie, prostate-specific antigen [PSA] response at week 25), regardless of metastases at baseline, and favorable tolerability. OBJECTIVE To determine the long-term efficacy and safety of enzalutamide monotherapy at 1 and 2 yr. DESIGN, SETTING, AND PARTICIPANTS Open-label, single-arm study in patients with HNPC and noncastrate testosterone (≥230 ng/dl). INTERVENTION Oral enzalutamide 160mg/d until disease progression or unacceptable toxicity. OUTCOME MEASUREMENTS AND ANALYSIS PSA response (≥80% decline from baseline) assessed at 1 yr (49 wk) and 2 yr (97 wk). RESULTS AND LIMITATIONS The median (range) age was 73 (48-86) yr and 26 patients (39%) presented with metastases at study entry. Of 67 patients enrolled, 45 (67%) remained on enzalutamide at week 97. For patients remaining on therapy, the PSA response rate at week 97 was 100% (95% confidence interval 92-100%). Of 26 patients with metastases at baseline, 13 (50%) had a complete and four (15.4%) had a partial response as best overall tumor response up to 97 wk on treatment. There was overall maintenance of total-body bone mineral density (BMD) and moderate changes in lean and fat body mass at 49 and 97 wk. The most common adverse events were gynecomastia, nipple pain, fatigue, and hot flushes. The study limitations include lack of a control group and of endocrine, glycemic, and lipid data at 97 wk. CONCLUSIONS Long-term enzalutamide monotherapy in men with noncastrate HNPC is associated with large sustained reductions in PSA, signals indicating a favorable tumor response, and favorable safety/tolerability profile, with relatively small negative effects on total-body BMD. PATIENT SUMMARY In this long-term follow-up of the efficacy and safety of enzalutamide monotherapy in patients with hormone-naïve prostate cancer, enzalutamide maintained long-term reductions in prostate-specific antigen, with a minimal impact on total-body bone mineral density. TRIAL REGISTRATION NCT01302041.

Enzalutamide in European and North American men participating in the AFFIRM trial

To explore any differences in efficacy and safety outcomes between European (EU) (n = 684) and North American (NA) (n = 395) patients in the AFFIRM trial (NCT00974311).

Antitumour Activity and Safety of Enzalutamide in Patients with Metastatic Castration-resistant Prostate Cancer Previously Treated with Abiraterone Acetate Plus Prednisone for ≥24 weeks in Europe

BACKGROUND Enzalutamide and abiraterone acetate plus prednisone, which target the androgen receptor axis, have expanded the treatment of advanced prostate cancer. Retrospective analyses suggest some cross-resistance between these two drugs when used sequentially, but robust, prospective studies have not yet been reported. OBJECTIVE To fulfil a regulatory postregistration commitment by evaluating the efficacy and safety of enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC) who progressed following abiraterone acetate plus prednisone treatment. DESIGN, SETTING, AND PARTICIPANTS Multicentre, single-arm, open-label study, enrolled patients with progressing mCRPC after ≥24 wk of abiraterone acetate plus prednisone treatment. All patients maintained castration therapy during the trial. Prior chemotherapy was allowed but not required. INTERVENTION Patients received enzalutamide 160mg/d orally. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The primary endpoint was radiographic progression-free survival. Secondary endpoints were overall survival, prostate-specific antigen (PSA) response, and time-to-PSA progression. Safety data were also assessed. Kaplan-Meier methods were used to descriptively analyse time-to-event endpoints. RESULTS AND LIMITATIONS Overall, 214 patients received enzalutamide treatment, 145 of whom were chemotherapy-naïve. Median radiographic progression-free survival was 8.1 mo (95% confidence interval: 6.1-8.3); median overall survival had not been reached. Unconfirmed PSA response rate was 27% (48 of 181). Median time-to-PSA progression was 5.7 mo (95% confidence interval: 5.6-5.8). The most common treatment-emergent adverse events were fatigue (32%), decreased appetite (25%), asthenia (18%), back pain (17%), and arthralgia (16%). No seizures were reported. CONCLUSIONS Enzalutamide showed antitumour activity in some patients with mCRPC who had previously progressed following ≥24 wk of abiraterone acetate plus prednisone treatment. PATIENT SUMMARY Patients with mCRPC who progressed on previous abiraterone acetate plus prednisone treatment, with or without prior chemotherapy, received enzalutamide. Although cross-resistance between the two agents was observed in a majority of patients, some still benefited from enzalutamide treatment.