A study presented at the ASTRO Annual Meeting found that adding the advanced PET radiotracer fluciclovine (Axumin) to conventional imaging for patients with recurrent prostate cancer may improve disease-free survival rates.
Adding the advanced PET radiotracer fluciclovine (Axumin) to conventional imaging for patients with recurrent prostate cancer may improve disease-free survival rates, according to results from the randomized phase 2/3 EMPIRE-1 trial presented at the American Society for Radiation Oncology (ASTRO) Annual Meeting.1
This was the first-ever randomized trial of PET over conventional imaging alone when finalizing post-prostatectomy radiotherapy decisions and target volumes.
Of patients whose prostate cancer had returned following surgical removal of their prostate, 75.5% whose treatment integrated the PET molecular imaging were disease-free after 3 years, compared to 63% for whom only conventional imaging techniques were used to plan treatment. This increased survival rate persisted for up to 4 years.
“The decision to offer post-prostatectomy radiation therapy is complex, because conventional imaging can leave unanswered questions on the best approach to treatment planning,” co-principal investigator Ashesh B. Jani, MD, FASTRO, a professor of radiation oncology at the Winship Cancer Institute of Emory University in Atlanta, said in a press release.2 “What this research has found is that integrating advanced molecular imaging into the treatment planning process allows us to do a better job of selecting patients for radiation therapy, guiding radiation treatment decisions and planning and ultimately, keeping patients' cancer under control."
The Emory Molecular Prostate Imaging for Radiotherapy Enhancement, or EMPIRE-1 trial (NCT01666808), enrolled 165 patients who had undergone prostatectomies, but who later showed abnormal PSA blood test scores. Each of the participants underwent conventional imaging for initial treatment planning and then were randomized into 2 groups.
The first cohort of patients (n =82) received radiation therapy based on the initial treatment plans described above. The remaining cohort of patients (n = 83) was given fluciclovine PET scans and treated based on the additional findings.
After 3 years, the study demonstrated that patients who were treated based on the more advanced imaging results, compared with the conventional arm, had a higher disease-free survival rate (P = .003), which continued for 4 years (75.5% vs 51%; P < .001). However, there were no significant differences noticed in provider-reported severe genitourinary or gastrointestinal side effects between the 2 arms.
Researchers suggested that these improved outcomes were most likely due to better patient selection, by excluding patients with extra-pelvic disease who are typically more susceptible to failure, as well as better definition of the tumor and treatment field.
“The reason we did this research was because we were frustrated that we could not get better cure rates for patients with this type of cancer,” co-principal investigator David M. Schuster, MD, a nuclear radiology specialist and professor at Emory University, said in the release. “We thought one of the factors involved may be the sensitivity of the imaging tests used for planning radiation therapy. We thought this new PET test, with its greater sensitivity for detecting prostate cancer, would translate into a better cure rate, as well. We believed there would be some effect but were pleasantly surprised by the strength of the findings.”
Of note, fluciclovine was approved for use by the FDA about halfway through the study in 2016 and is now widely used for the restaging of recurrent prostate cancer after its inclusion in the NCCN guidelines. However, it has not yet been widely accepted as the standard for planning treatment in this patient population.
Moving forward, the investigators have already begun evaluating whether a newer type of PET scan, which uses a radiotracer to target a receptor on the surface of prostate cancer cells, could be even more effective than fluciclovine in improving cancer control. Importantly though, the newer scan, called a prostate-specific membrane antigen (PSMA) test, is not yet FDA approved.
“Fluciclovine PET has become the best available test,” Schuster concluded. “But now there’s an even newer kid on the block. In EMPIRE-2, we’re building on the results of EMPIRE-1 by comparing PSMA with fluciclovine to see which one of these radiotracers improves cancer control better.”
1. Jani A, Schreibmann E, Goyal S, et al. Initial Report of a Randomized Trial Comparing Conventional- vs Conventional plus Fluciclovine (18F) PET/CT Imaging-Guided Post-Prostatectomy Radiotherapy for Prostate Cancer. Presented at the American Society for Radiation Oncology (ASTRO) Annual Meeting. Abstract #: LBA 1.
2. Adding advanced PET scans to radiation treatment plans for prostate cancer increases failure-free survival rates [news release]. Arlington, Virginia. Published October 26, 2020. Accessed October 30, 2020.