Prior Endocrine Therapy Impact on Abiraterone Acetate Clinical Efficacy in Metastatic Castration-resistant Prostate Cancer: Post-hoc Analysis of Randomised Phase 3 Studies.

The duration of prior hormonal treatment can predict responses to subsequent therapy in patients with metastatic castration-resistant prostate cancer (mCRPC). To determine if prior endocrine therapy duration is an indicator of abiraterone acetate (AA) sensitivity. Post-hoc exploratory analysis of randomised phase 3 studies examining post-docetaxel (COU-AA-301) or chemotherapy-naïve mCRPC (COU-AA-302) patients receiving AA. The treatment effect on overall survival (OS), radiographic progression-free survival (rPFS), and prostate-specific antigen (PSA) response analysed by quartile duration of prior gonadotropin-releasing hormone agonists (GnRHa) or androgen receptor (AR) antagonist. Patients were randomised to AA (1000mg, orally once daily) plus prednisone (5mg, orally twice daily) or placebo plus prednisone. Prior endocrine therapy was GnRHa (COU-AA-301, n=1127 [94%]; COU-AA-302, n=1057 [97%], 45.1 mo or 36.7 mo median duration, respectively) and/or orchiectomy (COU-AA-301, n=78 [7%] COU-AA-302, n=44 [4%]); castrated patients received prior AR antagonists (COU-AA-301, n=1015 [85%]; COU-AA-302, n=1078 [99%], 15.7 mo or 16.1 mo median duration, respectively). Cox model was used to obtain hazard ratio and associated 95% confidence interval with statistical inference by log rank statistic. Clinical benefit with AA was observed for OS, rPFS, and PSA response for nearly all quartiles with GnRHa or AR antagonists in both COU-AA-301 and COU-AA-302. In COU-AA-301, patients with a longer duration of prior endocrine therapy tended to have greater AA OS, rPFS, and PSA response benefit, with lead-time chemotherapy bias potentially impacting COU-AA-301 results. Time to castration resistance was not captured. This analysis is limited as a post-hoc exploratory analysis. In the COU-AA-301 and COU-AA-302 studies, AA produced clinical benefits regardless of prior endocrine therapy duration in patients with mCRPC. Metastatic castration-resistant prostate cancer patients derived clinical benefits with abiraterone acetate regardless of prior endocrine therapy duration.

Bellmunt J ，Kheoh T ，Yu MK ，Smith MR ，Small EJ ，Mulders PF ，Fizazi K ，Rathkopf DE ，Saad F ，Scher HI ，Taplin ME ，Davis ID ，Schrijvers D ，Protheroe A ，Molina A ，De Porre P ，Griffin TW ，de Bono JS ，Ryan CJ ，Oudard S ... -  《-》

Updated interim efficacy analysis and long-term safety of abiraterone acetate in metastatic castration-resistant prostate cancer patients without prior chemotherapy (COU-AA-302).

Abiraterone acetate (an androgen biosynthesis inhibitor) plus prednisone is approved for treating patients with metastatic castration-resistant prostate cancer (mCRPC). Study COU-AA-302 evaluated abiraterone acetate plus prednisone versus prednisone alone in mildly symptomatic or asymptomatic patients with progressive mCRPC without prior chemotherapy. Report the prespecified third interim analysis (IA) of efficacy and safety outcomes in study COU-AA-302. Study COU-AA-302, a double-blind placebo-controlled study, enrolled patients with mCRPC from April 2009 to June 2010. A total of 1088 patients were stratified by Eastern Cooperative Oncology Group performance status (0 vs 1). Patients were randomised 1:1 to abiraterone 1000mg plus prednisone 5mg twice daily by mouth versus prednisone. Co-primary end points were radiographic progression-free survival (rPFS) and overall survival (OS). Median times to event outcomes were estimated using the Kaplan-Meier method. Hazard ratios (HRs) and 95% confidence intervals (CIs) were derived using the Cox model, and treatment comparison used the log-rank test. The O'Brien-Fleming Lan-DeMets α-spending function was used for OS. Adverse events were summarised descriptively. With a median follow-up duration of 27.1 mo, improvement in rPFS was statistically significant with abiraterone treatment versus prednisone (median: 16.5 vs 8.2 mo; HR: 0.52 [95% CI, 0.45-0.61]; p<0.0001). Abiraterone improved OS (median: 35.3 vs 30.1 mo; HR: 0.79 [95% CI, 0.66-0.95]; p=0.0151) but did not reach the prespecified statistical efficacy boundary (α-level: 0.0035). A post hoc multivariate analysis for OS using known prognostic factors supported the primary results (HR: 0.74 [95% CI, 0.61-0.89]; p=0.0017), and all clinically relevant secondary end points and patient-reported outcomes improved. While the post hoc nature of the long-term safety analysis is a limitation, the safety profile with longer treatment exposure was consistent with prior reports. The updated IA of study COU-AA-302 in patients with mCRPC without prior chemotherapy confirms that abiraterone delays disease progression, pain, and functional deterioration and has clinical benefit with a favourable safety profile, including in patients treated for ≥24 mo. Study COU-AA-302, ClinicalTrials.gov number, NCT00887198. The updated results of this ongoing study showed that disease progression was delayed in patients with advanced prostate cancer who were treated with abiraterone acetate and prednisone, and there was a continued trend in prolongation of life compared with patients treated with prednisone alone. Treatment with abiraterone acetate and prednisone was well tolerated by patients who were treated for >2 yr.

Rathkopf DE ，Smith MR ，de Bono JS ，Logothetis CJ ，Shore ND ，de Souza P ，Fizazi K ，Mulders PF ，Mainwaring P ，Hainsworth JD ，Beer TM ，North S ，Fradet Y ，Van Poppel H ，Carles J ，Flaig TW ，Efstathiou E ，Yu EY ，Higano CS ，Taplin ME ，Griffin TW ，Todd MB ，Yu MK ，Park YC ，Kheoh T ，Small EJ ，Scher HI ，Molina A ，Ryan CJ ，Saad F ... -  《-》

Subsequent Chemotherapy and Treatment Patterns After Abiraterone Acetate in Patients with Metastatic Castration-resistant Prostate Cancer: Post Hoc Analysis of COU-AA-302.

Treatment patterns for metastatic castration-resistant prostate cancer (mCRPC) have changed substantially in the last few years. In trial COU-AA-302 (chemotherapy-naïve men with mCRPC), abiraterone acetate plus prednisone (AA) significantly improved radiographic progression-free survival and overall survival (OS) when compared to placebo plus prednisone (P). This post hoc analysis investigated clinical responses to docetaxel as first subsequent therapy (FST) among patients who progressed following protocol-specified treatment with AA, and characterized subsequent treatment patterns among older (≥75 yr) and younger (<75 yr) patient subgroups. Data were collected at the final OS analysis (96% of expected death events). Subsequent therapy data were prospectively collected, while response and discontinuation data were collected retrospectively following discontinuation of the study drug. At the discretion of the investigator, 67% (365/546) of patients from the AA arm received subsequent treatment with one or more agents approved for mCRPC. Efficacy analysis was performed for patients for whom baseline and at least one post-baseline prostate-specific antigen (PSA) values were available. Baseline and at least one post-baseline PSA values were available for 100 AA patients who received docetaxel as FST. While acknowledging the limitations of post hoc analyses, 40% (40/100) of these patients had an unconfirmed ≥50% PSA decline with first subsequent docetaxel therapy, and 27% (27/100) had a confirmed ≥50% PSA decline. The median docetaxel treatment duration among these 100 patients was 4.2 mo. Docetaxel was the most common FST among older and younger patients from each treatment arm. However, 43% (79/185) of older patients who progressed on AA received no subsequent therapy for mCRPC, compared with 17% (60/361) of younger patients. Patients with mCRPC who progress with AA treatment may still derive benefit from subsequent docetaxel therapy. These data support further assessment of treatment patterns following AA treatment for mCRPC, particularly among older patients. ClinicalTrials.gov NCT00887198. Treatment patterns for advanced prostate cancer have changed substantially in the last few years. This additional analysis provides evidence of clinical benefit for subsequent chemotherapy in men with advanced prostate cancer whose disease progressed after treatment with abiraterone acetate. Older patients were less likely to be treated with subsequent therapy.

de Bono JS ，Smith MR ，Saad F ，Rathkopf DE ，Mulders PFA ，Small EJ ，Shore ND ，Fizazi K ，De Porre P ，Kheoh T ，Li J ，Todd MB ，Ryan CJ ，Flaig TW ... -  《-》

The Phase 3 COU-AA-302 Study of Abiraterone Acetate Plus Prednisone in Men with Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer: Stratified Analysis Based on Pain, Prostate-specific Antigen, and Gleason Score.

In the COU-AA-302 study (NCT00887198), abiraterone acetate plus prednisone (AAP) significantly improved outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC) versus prednisone alone. Baseline clinical parameters predicting that treatment response could help inform clinical decisions were explored. To identify patients who derive the greatest clinical benefit from AAP treatment. A total of 1088 mCRPC patients treated with either AAP or prednisone in the first-line setting in COU-AA-302 were included in this post hoc analysis. Abiraterone acetate1000mg daily versus placebo, both plus prednisone 10mg daily. Univariate and multivariable Cox regression analyses were performed, including clinical and pathological parameters for the primary end points overall survival (OS) and radiographic progression-free survival (rPFS), and secondary study end points. Tumor-associated baseline parameters independently impacting OS were applied to stratify patients according to possible treatment effects. Baseline prostate-specific antigen (PSA), tumor-related pain as assessed by the Brief Pain Inventory-Short Form (BPI-SF), and Gleason score (GS) at primary diagnosis were identified as tumor-associated variables that independently impacted OS. AAP significantly improved outcomes versus prednisone in both group 1 (BPI-SF 0-1 and PSA <80 ng/ml and GS <8; p=0.006; hazard ratio [HR]: 0.61) and group 2 (BPI-SF 2-3 and/or PSA ≥80 ng/ml and/or GS ≥8; p=0.03; HR: 0.84). The differences observed for treatment effects between groups 1 and 2 for OS (HR: 0.61 vs 0.84), rPFS (HR: 0.41 vs 0.59), and time to chemotherapy (HR: 0.64 vs 0.71) were not statistically significant. AAP significantly improved outcomes in mCRPC patients compared with prednisone alone regardless of baseline pain and PSA level, and GS at primary diagnosis with no significant differences between observed treatment effects in groups 1 and 2. Treatment with abiraterone acetate and prednisone (compared with treatment with prednisone only) for metastatic castration-resistant prostate cancer increased survival in all patients in the study regardless of pain, prostate-specific antigen levels at the start of treatment, and Gleason score at primary diagnosis.

Miller K ，Carles J ，Gschwend JE ，Van Poppel H ，Diels J ，Brookman-May SD ... -  《-》

Impact of bone-targeted therapies in chemotherapy-naïve metastatic castration-resistant prostate cancer patients treated with abiraterone acetate: post hoc analysis of study COU-AA-302.

Metastatic castration-resistant prostate cancer (mCRPC) often involves bone, and bone-targeted therapy (BTT) has become part of the overall treatment strategy. Investigation of outcomes for concomitant BTT in a post hoc analysis of the COU-AA-302 trial, which demonstrated an overall clinical benefit of abiraterone acetate (AA) plus prednisone over placebo plus prednisone in asymptomatic or mildly symptomatic chemotherapy-naïve mCRPC patients. This report describes the third interim analysis (prespecified at 55% overall survival [OS] events) for the COU-AA-302 trial. Patients were grouped by concomitant BTT use or no BTT use. Radiographic progression-free survival and OS were coprimary end points. This report describes the third interim analysis (prespecified at 55% OS events) and involves patients treated with or without concomitant BTT during the COU-AA-302 study. Median follow-up for OS was 27.1 mo. Median time-to-event variables with 95% confidence intervals (CIs) were estimated using the Kaplan-Meier method. Adjusted hazard ratios (HRs), 95% CIs, and p values for concomitant BTT versus no BTT were obtained via Cox models. While the post hoc nature of the analysis is a limitation, superiority of AA and prednisone versus prednisone alone was demonstrated for clinical outcomes with or without BTT use. Compared with no BTT use, concomitant BTT significantly improved OS (HR 0.75; p=0.01) and increased the time to ECOG deterioration (HR 0.75; p<0.001) and time to opiate use for cancer-related pain (HR 0.80; p=0.036). The safety profile of concomitant BTT with AA was similar to that reported for AA in the overall intent-to-treat population. Osteonecrosis of the jaw (all grade 1/2) with concomitant BTT use was reported in <3% of patients. AA with concomitant BTT was safe and well tolerated in men with chemotherapy-naïve mCRPC. The benefits of AA on clinical outcomes were increased with concomitant BTT. Treatment of advanced prostate cancer often includes bone-targeted therapy. This post hoc analysis showed that in patients with advanced prostate cancer who were treated with abiraterone acetate and prednisone in combination with bone-targeted therapy, there was a continued trend in prolongation of life when compared with patients treated with prednisone alone. ClinicalTrials.gov NCT00887198.

Saad F ，Shore N ，Van Poppel H ，Rathkopf DE ，Smith MR ，de Bono JS ，Logothetis CJ ，de Souza P ，Fizazi K ，Mulders PF ，Mainwaring P ，Hainsworth JD ，Beer TM ，North S ，Fradet Y ，Griffin TA ，De Porre P ，Londhe A ，Kheoh T ，Small EJ ，Scher HI ，Molina A ，Ryan CJ ... -  《-》