David Forer

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.

Improved outcomes in elderly patients with metastatic castration-resistant prostate cancer treated with the androgen receptor inhibitor enzalutamide: results from the phase III AFFIRM trial

BACKGROUND The randomized, double-blind phase III AFFIRM trial demonstrated that enzalutamide, an oral androgen receptor inhibitor, significantly prolonged overall survival (OS) [median 18.4 versus 13.6 months (hazard ratio, HR) 0.63 (95% confidence interval, CI, 0.53-0.75); P<0.001] compared with placebo in patients with metastatic castration-resistant prostate cancer who received prior docetaxel chemotherapy. PATIENTS AND METHODS A post hoc analysis was carried out to assess the efficacy and safety of enzalutamide on outcomes in younger (<75 years) and elderly (≥75 years) patients in the AFFIRM population. Statistics are presented by age group (<75 years, ≥75 years) for efficacy outcomes of OS, radiographic progression-free survival (rPFS), time to prostate-specific antigen (PSA) progression, PSA response, and safety. RESULTS OS was significantly improved with enzalutamide over placebo in patients<75 years [median not yet reached versus 13.6 months; HR 0.63 (95% CI 0.52-0.78), P<0.001] and in patients ≥75 years [median 18.2 versus 13.3 months; HR 0.61 (95% CI 0.43-0.86), P=0.004], respectively. rPFS was similarly improved in both the younger [HR 0.45 (95% CI 0.38-0.53), P<0.001] and elderly patient cohorts [HR 0.27 (95% CI 0.20-0.37), P<0.001] relative to placebo, as were time to PSA progression and PSA response. Adverse events (AEs) were similar between the two enzalutamide age groups, with the exception of an increase in patients≥75 years in the rates of all grade peripheral edema (22.1% versus 12.5%), fatigue (39.7% versus 31.6%), and diarrhea (26.6% versus 19.6%). The overall grade≥3 AE rates were low with no major difference in frequency or severity between age groups or treatment arms. Five patients were reported with seizure events; three patients<75 years and two patients ≥75 years. CONCLUSIONS Enzalutamide significantly improves outcomes in both younger (<75 years) and elderly patients (≥75 years), with comparable safety and tolerability.

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 and safety of enzalutamide in patients 75 years or older with chemotherapy-naive metastatic castration-resistant prostate cancer: results from PREVAIL

BACKGROUND Prostate cancer disproportionately affects older men. Because age affects treatment decisions, it is important to understand the efficacy and tolerability of therapies for advanced prostate cancer in elderly men. This analysis describes efficacy and safety outcomes in men aged ≥75 years who received enzalutamide, an androgen receptor inhibitor, in the phase III PREVAIL trial. PATIENTS AND METHODS PREVAIL was a randomised, double-blind, multinational study of oral enzalutamide 160 mg/day (N = 872) versus placebo (N = 845) in chemotherapy-naive men with metastatic castration-resistant prostate cancer. Overall survival (OS) and radiographic progression-free survival (rPFS) were coprimary end points. Subgroup analysis of men aged ≥75 years (elderly) and men aged <75 years was pre-specified for the coprimary end points and adverse events (AEs). RESULTS Among 609 elderly patients (35%) who participated in PREVAIL, median treatment duration was 16.6 and 5.0 months in the enzalutamide and placebo arms, respectively. In the elderly subgroup, OS was greater with enzalutamide than with placebo [32.4 months (95% confidence interval (CI) 27.7-not yet reached] versus 25.1 months (95% CI 22.6-28.0); hazard ratio (HR) = 0.61 (95% CI 0.47-0.79); P = 0.0001], as was rPFS [not yet reached (95% CI 12.3-not yet reached) versus 3.7 months (95% CI 3.6-5.3); HR = 0.17 (95% CI 0.12-0.24); P < 0.0001]. Irrespective of treatment assignment, incidence of AEs was similar between the two age groups, except for an overall higher incidence of falls among elderly patients than younger patients [84/609 (13.8%) versus 62/1106 (5.6%)] and among elderly patients receiving enzalutamide than those receiving placebo [61/317 (19.2%) versus 23/292 (7.9%)]. CONCLUSIONS Elderly men benefited from treatment with enzalutamide in terms of OS and rPFS. Enzalutamide was well tolerated in the elderly subgroup and those aged <75 years. Age and enzalutamide treatment were associated with a higher incidence of falls. CLINICAL TRIAL IDENTIFIER NCT01212991, ClinicalTrials.gov.

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.

Enzalutamide in combination with docetaxel in men with prostate cancer (PC): Preliminary results from a phase I study.

63 Background: Enzalutamide (ENZA), a novel oral androgen receptor (AR) inhibitor, inhibits AR signaling via inhibition of androgen binding to the AR, AR nuclear translocation, and nuclear AR-DNA binding. ENZA demonstrated a survival benefit in men with metastatic castration-resistant prostate cancer (mCRPC) who had received prior docetaxel (Scher et al, NEJM 2012; 367:1187). A Phase III study in men with progressive chemotherapy-naïve disease (PREVAIL), is ongoing. Docetaxel (DOC) is the current standard first-line chemotherapy for mCRPC. CYP3A4, which plays a role in DOC clearance, is induced by ENZA. Patients (pts) eligible to receive DOC may benefit from continued AR inhibition with ENZA, provided the combination is well tolerated with no unacceptable drug-drug interactions. METHODS This study evaluated the safety and pharmacokinetics (PK) of DOC co-administered with ENZA in men with mCRPC on androgen deprivation therapy. Pts received DOC (75 mg/m2) by 1-h infusion every 3 weeks, with corticosteroids. ENZA (160 mg/d) was started 24 h after the first DOC infusion. Plasma PK samples were collected for 24 h after Cycle (C) 1 and C2 DOC infusions to enable within-subject comparisons of DOC PK ± ENZA. A sample size of 18 pts able to receive ≥ 2 full doses of DOC was specified for PK analyses. RESULTS As of 21 Sept. 2012, 22 pts have been enrolled, 3 did not complete both C1 and C2; PK and C1 and C2 safety data are currently available from 15 pts reported here. The median age was 65 (range 46-80 yrs); 11 had ECOG performance status 1 (vs 0). Prior primary therapy included surgery (n=2), radiation (n=4) or both (n=5); median PSA was 44.7ng/mL (1.9-585). ANC<1000mm3 was reported in 14 pts (1 febrile neutropenia), other adverse events in ≥4 pts included fatigue (11), dyspnea (6), alopecia (5), peripheral neuropathy (5), anemia (4) and dysgueusia (4). No seizures were reported. Preliminary PK data (n=15) show similar DOC exposure (within 20%) for DOC in combination with ENZA vs. DOC alone. CONCLUSIONS This is the first evaluation of ENZA given in combination with DOC.In mCRPC pts ENZA does not appear to affect tolerability of DOC or have a clinically meaningful impact on DOC PK. CLINICAL TRIAL INFORMATION NCT01565928.

Clinical outcomes and survival surrogacy studies of prostate‐specific antigen declines following enzalutamide in men with metastatic castration‐resistant prostate cancer previously treated with docetaxel

In the AFFIRM trial, enzalutamide significantly increased overall survival (OS) for men with metastatic castration‐resistant prostate cancer (mCRPC) after chemotherapy versus placebo and significantly decreased prostate‐specific antigen (PSA) levels. The goal of this post hoc analysis was to associate levels of PSA decline from baseline after enzalutamide with clinical outcomes in the postchemotherapy mCRPC setting.

Long-term responders to enzalutamide (ENZA) during the phase III AFFIRM trial: Baseline characteristics and efficacy outcomes.

20 Background: ENZA, an oral androgen receptor inhibitor, was shown to significantly increase overall survival by 4.8 mo (P <0.001, HR 0.63) vs placebo (PBO) in AFFIRM, a phase III trial in patients (pts) with castration resistant prostate cancer (CRPC) post- docetaxel. Here we report the baseline characteristics and efficacy outcomes of long-term responders (LTR, ≥12 months on ENZA) in the AFFIRM trial. METHODS Pts were randomized 2:1 to ENZA 160 mg/day or PBO. The primary endpoint was overall survival (OS). The study was stopped at the pre-specified interim analysis (520 events). Pts in the ENZA group were allowed to continue on ENZA post unblinding. The LTR group was defined by Aug 2012 data cut-off. Efficacy data are from interim analysis data cut-off from Sep 2011. RESULTS 35% (276/800) of the ENZA group were on therapy for ≥ 12 months; 22% (174/800) for > 18 months. Comparing the LTR subgroup to the all ENZA group, the LTR subgroup had been living with prostate cancer longer (7.9 vs 5.9 yrs) and had lower disease burden at baseline (Table). Pts in the LTR subgroup had improved efficacy outcomes compared to all ENZA group. Of note, 50% PSA response was 87% in LTR subgroup vs 54% in the all ENZA group. Results are preliminary, updated results will be presented. CONCLUSIONS 35% of pts in AFFIRM received ENZA for ≥12 months. Compared to the all ENZA group, LTR pts had less disease burden at baseline and had improved efficacy outcomes. CLINICAL TRIAL INFORMATION NCT00974311. [Table: see text].

Outcomes in elderly patients with metastatic castration-resistant prostate cancer (mCRPC) treated with the androgen receptor inhibitor enzalutamide: Results from the phase III AFFIRM trial.

16 Background: Enzalutamide (ENZA) inhibits multiple steps in the androgen receptor signaling pathway (Tran et al, Science. 2009;324:787). The phase III AFFIRM trial demonstrated that ENZA increased median overall survival (OS) by 4.8 months with a 37% reduction in the risk of death (P <0.001, HR 0.63) vs placebo (PBO) in post-docetaxel mCRPC patients (pts) (Scher et al, NEJM 2012; 367:1187). In a post-hoc analysis, the effect of ENZA on outcomes in elderly (≥ 75 yrs) vs younger (< 75 yrs) pts in the AFFIRM trial was assessed. METHODS The AFFIRM trial was a Phase III multinational, randomized, double-blind study in post-docetaxel mCRPC pts. Randomization was 2:1 to ENZA 160 mg/day or PBO, stratified by baseline ECOG performance status and mean pain score. Statistics are presented by age group (≥75, yrs <75 yrs) for efficacy outcomes of OS, radiographic progression-free survival (rPFS), and time to prostate-specific antigen (PSA) progression. Top line safety results are also presented for both age groups. RESULTS Elderly pts comprised 25% (199/800) of ENZA pts and 26% (104/399) of PBO pts. Improved outcomes with ENZA treatment were observed in both elderly and younger pts, with similar safety profiles in each age group. CONCLUSIONS ENZA significantly improved outcomes in both elderly (≥ 75yrs) and younger pts (< 75yrs). Safety and tolerability findings were comparable between the two age groups. CLINICAL TRIAL INFORMATION NCT00974311. [Table: see text].

Enzalutamide in castration‐resistant prostate cancer patients with visceral disease in the liver and/or lung: Outcomes from the randomized controlled phase 3 AFFIRM trial

Patients with metastatic castration‐resistant prostate cancer (mCRPC) and visceral metastases have a worse prognosis than those with nonvisceral metastases. Treatment with the androgen receptor inhibitor enzalutamide in the phase 3 AFFIRM trial led to significant improvements in outcomes for patients with mCRPC. For the current report, the authors analyzed the efficacy of enzalutamide among patients from the AFFIRM trial who had visceral disease.