FDA Grants Priority Review to New Indication for Abiraterone Acetate

The FDA announced that Priority Review has been granted to abiraterone acetate (Zytiga, Janssen) for certain advanced prostate cancer cases based on positive data presented at the American Society of Clinical Oncology (ASCO) meeting earlier this year.

Abiraterone acetate, when given in combination with prednisone, was approved by the FDA in 2011 to treat patients with metastatic castration-resistant prostate cancer (mCRPC) who had previously received docetaxel. However, Janssen submitted a supplemental New Drug Application (sNDA) for another indication. The FDA is reviewing whether the combination of abiraterone acetate with prednisone would benefit mCRPC patients who are asymptomatic or mildly symptomatic after failure of androgen deprivation therapy (ADT) but who have not received chemotherapy.

“We believe that men with mCRPC whose disease is asymptomatic or mildly symptomatic, for whom chemotherapy may not be immediately necessary, have limited treatment options and that this disease setting represents a critical unmet medical need,” said Michael L. Meyers, MD, PhD, vice president and compound development team leader for Zytiga, in a statement. “We are delighted the FDA has granted a Priority Review designation for our supplemental New Drug Application.”

At the ASCO meeting this summer, researchers presented an interim analysis of data from the ongoing COU-AA-302 study. The study enrolled 1088 chemotherapy-naïve, asymptomatic or mildly symptomatic patients with mCRPC, who were then randomized 1:1 to receive either 1 g of abiraterone once daily plus 5 mg of prednisone twice daily or placebo plus 5 mg of prednisone twice daily.

The interim analysis was based on 43% of total events being reported. The median progression-free survival (PFS) in the control arm was 8.3 months; however, the median PFS could not be determined for the abiraterone group. An independent analysis of the data found that the median PFS appeared to be approximately doubled in the abiraterone arm (hazard ratio [HR] = 0.43; 95% CI, 0.35-0.52; P <.0001).

The interim analysis could not determine the median overall survival (OS). However, the OS in the control arm was 27.2 months, the longest median OS measured in any phase III mCRPC study. The independent analysis showed that there was an approximate 25% increase in OS in the abiraterone arm (HR = 0.75; 95% CI, 0.61-0.93; P = .0097).

The study was unblinded in March so that patients in the control arm could receive abiraterone.

Now that abiraterone acetate has been given Priority Review status, the FDA is expected to conclude its review within six months of the sNDA submission, which Janssen submitted in June.

Ryan CJ, Smith MR, De Bono JS, et al. Interim analysis (IA) results of COU-AA-302, a randomized, phase III study of abiraterone acetate (AA) in chemotherapy-naïve patients (pts) with metastatic castration-resistant prostate cancer (mCRPC). J Clin Oncol. 2012;30(suppl; abstr LBA4518).