Data from a post-hoc analysis of the Phase 3 COU-AA-302 trial has showed that abiraterone acetate (marketed as Zytiga) plus prednisone provided an 11.8 months overall survival (OS) benefit (53.6 months vs 41.8 months; HR = 0.61 [95% CI, 0.43-0.87]; p = 0.0055), compared to an active control of placebo plus prednisone, in men with early and less aggressive chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC).¹

Data from the post-hoc analysis, presented today at the European Association of Urology (EAU) 2016 Congress in Munich, Germany, demonstrated an increase in the OS benefit previously shown (4.4 months) in the final analysis of the COU-AA-302 trial (34.7 months abiraterone acetate plus prednisone vs 30.3 months placebo plus prednisone; HR = 0.81 [95% CI, 0.70-0.93]; p = 0.0033).

The final analysis was originally presented at the European Society for Medical Oncology (ESMO) 2014 Congress and included a broader range of men with asymptomatic or mildly symptomatic chemotherapy-naïve mCRPC.²

The post-hoc analysis divided patients into two groups to identify which group experienced a greater treatment benefit.

The patients in Group 1 were in an earlier, less advanced and less symptomatic stage of the disease (which was defined as having a Brief Pain Inventory [BPI] Short Form score of 0-1, prostate-specific antigen [PSA] below 80 ng/ml and a Gleason score [GS] of below 8).

Those in Group 2 were in a later, more advanced and more symptomatic stage of the disease (defined as a having a BPI of 2 or over and/or PSA of 80 ng/ml or above, and/or a GS of 8 or more).

The analysis revealed that patients in both groups experienced an OS benefit when treated with abiraterone acetate plus prednisone, compared to placebo plus prednisone (Group 1: 11.8 months; HR = 0.61 [95% CI, 0.43-0.87]; p = 0.0055) (Group 2: 2.8 months; HR = 0.84 [95% CI, 0.72-0.99]; p = 0.0321).¹

“Post-hoc analyses such as this are very important in helping us to identify the patients who could benefit most from therapies such as novel hormone agents, and at what stage of a patient’s disease they could be most effective”, said Professor Kurt Miller, Department of Urology, Charité Berlin, Berlin, Germany.

“As men with prostate cancer are living longer, quality of life is an increasingly important factor for them and their families. It is therefore encouraging to see that when used earlier, patients can stay on abiraterone acetate for longer and delay the need for additional, more invasive treatments”, he continued.

In addition to OS benefit, the post-hoc analysis data also revealed that both groups showed improvement in disease progression, cancer-related pain and treatment duration when treated with abiraterone acetate plus prednisone, compared to placebo plus prednisone:

• Time to chemotherapy use was increased by 12.7 months in Group 1 and 8.8 months in Group 2
• Group 1: 37.0 months vs 24.3 months; HR = 0.64 [95% CI, 0.46-0.89]; p = 0.0073
• Group 2: 23.3 months vs 14.5 months; HR = 0.71 [95% CI, 0.60-0.85]; p = 0.0001
• There was an improvement in median time to opiate use for cancer-related pain in both groups
• Group 1: not reached vs 41.0 months; HR = 0.69 [95% CI, 0.48-0.99]; p = 0.0409
• Group 2: 30.5 months vs 19.3 months; HR = 0.70 [95% CI, 0.59-0.84]; p = 0.0001
• Median time on treatment increased in both groups
•  Group 1: 20.4 months vs 11.2 months; HR = 0.41 [95% CI, 0.31-0.54]; p < 0.0001
• Group 2: 12.3 months vs 7.2 months; HR = 0.54 [95% CI, 0.46-0.62]; p < 0.0001

References

1. Miller, K. et al. 'The phase 3 COU-AA-302 study of abiraterone acetate (AA) in men with chemotherapy (CT)-naïve metastatic castration-resistant prostate cancer (mCRPC): Stratified analysis based on pain, prostate-specific antigen (PSA) and Gleason score (GS).' Poster session #61 presented at the European Association of Urology 2016 Congress, March 11-15, Munich, Germany.

2. Ryan C.J et al. 'Final overall survival (OS) analysis of COU-AA-302, a randomized phase 3 study of abiraterone acetate (AA) in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) without prior chemotherapy.' Abstract presented at the European Society for Medical Oncology 2014 Congress, September 26-30, Madrid, Spain. Oral Presentation. ESMO abstract #753O. Available at: https://www.webges.com/cslide/library/esmo/browse/search/eor#9f9k02Lm. Last accessed September 2014.

Source: Janssen-Cilag International