The most common laboratory abnormalities included anemia; elevations in alkaline phosphatase, triglycerides, and cholesterol; hyperglycemia; lymphopenia; hypophosphatemia; and hypokalemia.
Dr. Richard Pazdur
The expanded approval "demonstrates the benefit of further evaluating a drug in an earlier disease setting and provides patients and health care providers the option of using Zytiga earlier in the course of treatment," Dr. Richard Pazdur, director of the Office of Oncology Drug Products in the FDA’s Center for Drug Evaluation and Research, said in the FDA’s statement announcing the approval.
First-Line Use Possible in Future
In the interview, Dr. Moul predicted that abiraterone may have a role as a first-line treatment in the future, referring to a clinical study of abiraterone combined with traditional androgen deprivation prior to radical prostatectomy "that showed a fairly dramatic shrinkage of the tumor."
The new options for treating advanced prostate cancer that have become available since the spring of 2010 have generated questions over the use and sequencing of these agents, he said.
"For example, should doctors use Provenge before or after Zytiga? Should doctors use Provenge and Zytiga together since they are now both FDA approved in the same setting, prechemotherapy? Should some patients still start with chemotherapy first?" he asked.
Dr. Moul described enzalutamide as another "very promising" oral cancer therapy, which also may eventually be approved in the prechemotherapy setting for castration-resistant prostate cancer. "Then doctors and patients will have three choices in Provenge, Zytiga, and Xtandi, and they will have to figure out how to sequence this new feast of agents," he said.
Dr. Moul is a paid consultant to Janssen; he was not an investigator in the study that was the basis of the expanded approval. One of the study investigators, Dr. Daniel George, is the director of the section of genitourinary medical oncology at Duke University Medical Center.