FDA Approves Abiraterone as Prostate Cancer Treatment

Abiraterone acetate, a first-in-class compound that has demonstrated the ability to extend survival in patients with metastatic castrate-resistant prostate cancer (mCRPC), gained FDA approval Thursday, nearly 2 months ahead of the regulatory deadline.

The agency approved the use of the drug in combination with prednisone for the treatment of patients with mCRPC who already have been treated with docetaxel. Centocor Ortho Biotech Inc, a Horsham, Pennsylvania-based company, will market the drug under the trade name Zytiga.

In its approval notice, the FDA cited the results of a multinational, randomized phase III trial that demonstrated a >35% improvement in survival for patients treated with abiraterone. The study, which involved 1195 patients with mCRPC, resulted in a median overall survival for those in the abiraterone arm of 14.8 months versus 10.9 months for the placebo arm.

“Zytiga prolonged the lives of men with late-stage prostate cancer who had received prior treatments and had few available therapeutic options,” Richard Pazdur, MD, director of the Office of Oncology Drug Products in the FDA’s Center for Drug Evaluation and Research, said in a press release.

Abiraterone acetate inhibits the dual enzyme complex, CYP17 (17 α hydroxylase and C_17,20-Lyase), which is principally responsible for synthesizing the androgen that stimulates tumor growth. The drug is administered in 1000-mg doses.

Excitement about the drug’s potential has been building for more than a year. Leading prostate cancer experts speaking at the 4th Annual Interdisciplinary Prostate Cancer Congress, held in New York City in March, were anticipating its approval.

Robert Dreicer, MD, chairman of the Department of Solid Tumor Oncology at the Taussig Cancer Institute at the Cleveland Clinic and professor of Medicine at the Cleveland Clinic Lerner College of Medicine in Ohio, said the pivotal study for the drug was “unequivocally a positive trial of an oral, well-tolerated therapy.”

The 3 most frequently reported events were fluid retention, hypokalemia, and cardiac disorders; the incidence of grades 3/4 events among these complaints was 2.3%, 3.8%, and 4.1%, respectively.

"As a clinician, I believe the efficacy and safety profile of abiraterone acetate, as well as its oral, once-daily formulation, will help address the important need for additional therapeutic choices for men living with this serious disease," said Howard Scher, MD, chief of the Genitourinary Oncology Service, Sidney Kimmel Center for Urologic and Prostate Cancers at Memorial Sloan-Kettering, and one of the co-lead investigators for the phase III clinical study, in a press release from Centocor Ortho Biotech.

The company submitted a new drug application to the FDA in December under the agency’s priority review program, which required a decision by June 20.