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Imaging Agent Changes Treatment of Recurrent Prostate Cancer

Samson, Kurt

doi: 10.1097/01.COT.0000527886.89287.23
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Six in 10 prostate cancer patients with molecular signs of biochemically recurrent disease underwent changes in their management plans after undergoing CT/PET scans with the new imaging agent fluciclovine, according to planned interim data from a U.K.-based, prospective, multicenter, open-label study.

Fluciclovine F-18 was approved in 2016 for imaging of men with suspected prostate cancer recurrence based on elevated blood levels of prostate specific antigen (PSA), but has yet to be approved for treatment planning in men with biochemically recurrent (BCR) prostate cancer.

Recruitment in the FALCON trial was halted early after positive results from the interim analysis in the first 85 men were evaluated. Positive PET/CT scans contributed to treatment changes in 52 out of the 85 patients, including 42 instances where changes were a direct result of imaging findings. Major revisions were made in 31 of the 52 patients.

Study results were discussed in an oral presentation at this year's American Society for Radiation Oncology (ASTRO) Annual Meeting.

The findings could have a significant impact on the clinical management of men with a first BCR after curative-intent therapy, noted Eugene J. Teoh, MD, MRCP, FRCR, a researcher in the FALCON clinical trial and Radiation Oncologist at Oxford University Hospitals, NHS Foundation Trust, Oxford, U.K.

“When BCR of prostate cancer is suspected, early and accurate localization of metastases facilitates treatment when tumors are small and most amenable to localized therapy, and it may guide clinicians in making management plans regarding salvage therapy,” he stated.

“Some subjects had treatment plans rationally modified to provide a better chance of cure or to avoid possibly futile salvage therapy,” he continued. “Future studies are needed to assess the long-term impact of these management changes on disease outcomes. Follow-up is underway to assess PSA response to treatment.”

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Methods, Results

Participants included men with a biochemical recurrence of prostate cancer who were eligible for salvage therapy and their intended management plans were recorded before and after 18F-fluciclovine PET/CT imaging.

All of the men had a first BCR episode after radical therapy and, among the 85 patients who underwent imaging, 65.9 percent had previously undergone radical prostatectomy.

The primary outcome measure was the impact of 18F-fluciclovine PET/CT on clinical management decisions. Diagnostic accuracy using clinical follow-up, histological correlation, and concordance with multimodal imaging was a secondary outcome.

Changes in treatment modality, such as salvage radiation therapy to hormone deprivation, were classified as “major,” while changes within a modality, for example, alteration to salvage radiation therapy fields, were designated “other.”

Based upon an anticipated 40 percent change in management, the preplanned analysis of the first 85 patients was performed with intent to terminate recruitment for overwhelming efficacy if treatment changes exceeded 45, or for futility if fewer than eight plans were altered.

CT/MRI using 18F-fluciclovine detected lesions in the prostate/bed or extraprostatic region in 40.0 percent and 22.4 percent of scans, respectively.

Therapeutic management was revised in 52/85 (61.2%) of patients. In 41 of the 52 patients, the decision was based on a positive finding on the 18F-fluciclovine scan. Among those with treatment changes, major revisions were made for 32/52 (61.5%) of those subjects with updated plans.

Salvage treatment was revised to watchful waiting in 13 of the 85 patients (15.3%) and to systemic therapy for 18/85 (21.2%), while 20/85 (23.5%) had their planned radiation therapy field modified to include a boost to a positive lesion or to widen the field to include the whole pelvis.

Researchers also announced the updated status of its investigational LOCATE study on the impact of 18F-fluciclovine on management of patients with rising PSA scores after initial treatment. Patient enrollment was completed earlier than anticipated and analysis of the data from the 15 clinical sites involved in the study is currently underway in hopes of being submitted and published in 2018.

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Commentary

“The FALCON trial has the potential to be truly practice-changing. It is exciting to see coming on the heels of the relatively recent approval of the F-18 imaging agent [for recurrence based on rising PSA scores],” David C. Beyer, MD, Immediate Past Chair of ASTRO and Medical Director of Cancer Centers of Northern Arizona at Sedona, told Oncology Times.

Men with a biochemical recurrence may undergo radiation therapy of the surgical bed, management with hormonal therapy, or simply be observed,” he noted. “Today, we have no way to inform the decision with patient specific data. This new imaging agent changed the treatment plan in most men and gets us closer to personalized care for a group who deserve more individualized—and more effective—treatments.”

Abhishek Solanki, MD, Assistant Professor of Radiation Oncology at Loyola University School of Medicine, Chicago, noted that BCR prostate cancer poses an important medical challenge.

“Currently approved anatomical imaging procedures have limitations in identifying the sites of recurrence after definitive treatment, which can make decision-making difficult when assessing patients with biochemical recurrence. Newer imaging techniques, such as F-18 fluciclovine PET/CT, may provide actionable information for physicians in guiding appropriate patient management.”

Judd Moul, MD, Professor of Urologic Surgery at Duke University School of Medicine, Durham, N.C., also commented on the findings.

“Selecting appropriate patient care options for men with biochemically recurrent prostate cancer is critical,” he said. “Many options are available, and some patient management plans may carry uncertainty that could potentially be alleviated by more accurate information. Clinical studies are important to investigate the role that reliable information provided by diagnostic imaging can play in guiding appropriate management for men with recurrent prostate cancer.”

Kurt Samson is a contributing writer.

Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
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