Strong evidence, standardization needed
In a discussion of the paper, Tyler Seibert, MD, PhD, of the University of California San Diego, said that “escalation by 24 months has the strongest evidence today, specifically from the RADICALS-HD trial, with more than 1,500 men with 10 years of follow-up and a clear statistically significant result.
“Intensification for 6 months is a very compelling concept, as most patients are not getting 2 years of androgen deprivation therapy at this point post prostatectomy,” he continued. “While we await the long term follow-up of this study and the pending PROSTATE IQ trial, and if only 6 months of therapy is acceptable or feasible, the FORMULA-509 [trial] provides convincing evidence that select patients would benefit from intensification with AAP and apalutamide.”
Another expert weighed in on the data. Approached by this news organization for an independent comment, Jeff M. Michalski, MD, MBA, professor of radiation oncology at Washington University, St Louis, and president of the American Society of Radiation Oncology, noted a few issues in the study.
He said that standards had changed since this study was first approved and had begun accrual several years ago. “In context of today’s era, the current standard is to do a PET scan if patients have a chemical failure after surgery,” he said. “The PSA levels of patients who were treated [in this trial] were very high, and many patients do not want to wait until they reach that level.”
Dr. Michalski also pointed out the number of patients getting radiation was less than the number who had node-positive disease. “This shows that patients had received suboptimal therapy late in the disease,” he said.
Overall, most patients in the study did not receive lymph node radiation, even though they had high-risk features. “A recent study of almost 1,800 patients that was published in The Lancet found that there is a benefit to pelvic lymph node radiation,” he said. “Because it wasn’t mandated, most of the patients did not receive pelvic lymph node radiation, which we now understand offers some benefit.”
The reasons for not giving pelvic radiation to these men is unclear. “Treatment was left at the discretion of the physician and this could create bias,” Dr. Michalski said. “It could drive one arm more than another.”
The study also wasn’t controlled for pelvic radiation. “Most of the nodal positive patients received it, but the other patients were undertreated,” he noted.
Dr. Michalski added that he hopes that in the forthcoming PROSTATE IQ study, lymph node radiation and imaging are standardized.
The trial was supported by Janssen Oncology. Dr. Nguyen disclosed relationships with, and/or support from, Volatilyx, Bayer, Blue Earth Diagnostics, Boston Scientific, Janssen Oncology, Myovant Sciences, Astellas Pharma, and Janssen. Dr. Seibert disclosed relationships with, and/or support from, CorTechs Labs, Varian Medical Systems, and GE Healthcare.
A version of this article first appeared on Medscape.com.
