IMAAGEN Trial Secondary End Points Updated

San Diego—Researchers led by Charles Ryan, MD, presented updated results of secondary end points of the IMAAGEN (Impact of Abiraterone Acetate in Prostate Specific Antigen) study at the AUA 2016 Annual meeting during a session titled Impact of Abiraterone Acetate in Prostate Specific Antigen Trial Update: Effect of Abiraterone Acetate and Low Dose Prednisone on Prostate-Specific Antigen and Radiographic Disease Progression in Patients with Non-Metastatic Castration Resistant Prostate Cancer.

Abiraterone acetate at 1000 mg, in combination with prednisone 10 daily, is indicated for the treatment of patients with metastatic castration resistant prostate cancer (mCRPC). The IMAAGEN trial is a phase 2, multi-center study designed to evaluate the ability of abiraterone acetate plus 5 mg prednisone to decrease prostate specific antigen (PSA) levels in patients with non-metastatic CRPC (nmCRPC) and a rising PSA. Primary results of the study have been reported earlier [ASCO 2014 IMAAGEN primary end point poser presentation].

All patients enrolled in IMAAGEN had high-risk nmCRPC, defined as PSA value ≥10 ng/mL or PSA doubling time ≤10 months at screening. Patients received abiraterone acetate plus 5 mg prednisone daily for treatment cycles of 28 days. Reported end points included time to PSA progression, time to radiographic progression, and safety.

At data cutoff (November 3, 2014), 47.3% (n=62/131) of the patients enrolled in IMAAGEN remained on treatment in the study. Median duration of exposure was 17.9 months; median time to PSA progression was 28.7 months. There were 21 confirmed radiographic progression events; median time to radiographic progressive disease was not reached.

Adverse events were reported in 95.4% of patients. Of those, 54.9% had a grade 3 or higher adverse event and 38.2% had a serious adverse event (35.9% had a grade 3 or higher serious adverse event). Of the patients with adverse events, 13.0% discontinued study treatment, and four had adverse events resulting in death (coronary artery disease, myocardial infarction, acute respiratory failure, and pneumonia).

“Treatment of high risk nmCRPC patients with abiraterone acetate plus 5 mg prednisone resulted in a median time to PSA progression of 28.7 months. The median time to radiographic disease progression was not reached. The safety profile of abiraterone acetate plus 5 mg prednisone reported in this IMAAGEN trial update is consistent with the safety profile from previously reported studies of abiraterone acetate 1000 mg in combination with either 5 mg or 10 mg prednisone,” the researchers said.

Source: Ryan C, Crawford E D, Shore, N D, et al. Impact of abiraterone acetate in prostate specific antigen trial update: effect of abiraterone acetate and low dose prednisone on prostate-specific antigen and radiographic disease progression in patients with non-metastatic castration resistant prostate cancer. Abstract of a presentation at the American Urological Association 2016 Annual Meeting, May 8, 2016, San Diego, California. Funding was supplied by Janssen Pharmaceuticals.