RTOG Foundation STEEL Trial Exceeds Patient Accrual Goal

August 29, 2022

The RTOG Foundation RTOG 3506 trial, also known as the “STEEL” study, recently completed patient accrual above the projected accrual goal. The Phase II, limited-participation study comparing salvage radiotherapy (SRT) with standard androgen deprivation therapy (ADT) to enhanced ADT with enzalutamide in patients with post-prostatectomy PSA recurrences with aggressive disease features was expected to enroll 170 patients, however the trial official closed to patients with 188 patients accrued. This trial was performed in collaboration with Astellas and Pfizer.

Retrospective analyses of clinical data suggest that SRT has provided long-term durable responses and potential improvement of outcomes for prostate cancer-specific mortality when compared to observation following biochemical recurrence. The STEEL trial aims to lengthen progression-free survival for these patients by adding enhanced ADT with enzalutamide to SRT.

“The STEEL study was designed to address a dire need for improved outcomes for prostate cancer patients with PSA recurrences with aggressive features following prostatectomy. Although SRT is a widely-accepted treatment option for patients with post-prostatectomy PSA recurrences, including those with aggressive features, up to half of the patients treated with SRT will experience disease progression,” stated Edwin Posadas, MD, FACP, of Cedars-Sinai Medical Center and the Principal Investigator of the STEEL study. “The addition of ADT to SRT has already made improvements in lowering rates of biochemical recurrence. Adding enhanced ADT with enzalutamide to the SRT treatment could allow us to intensify the effects of ADT to further improve and lengthen survival.”

The STEEL trial has several secondary objectives to compare rates of biochemical failure, an alternative biochemical failure endpoint, hormone-refractory disease, distant metastasis, cause-specific mortality, overall mortality, acute and late physician- and patient-reported toxicity, fatigue, and global quality of life between patients on both treatment arms.

“Thank you to the RTOG Foundation sites, research staff, our partners, and the patients who helped the STEEL trial to reach this incredibly important milestone. We look forward to our continued follow up of the information collected during this trial,” added Hiram Gay, MD, of the Department of Radiation Oncology and the Co-Principal Investigator of the STEEL study.

Results from the trial data will be reported when they become available.


About RTOG Foundation

The RTOG Foundation is a nonprofit organization dedicated to improving outcomes for cancer patients through the conduct of practice changing clinical trials. RTOGF collaborates with partners from industry and federally funded programs to support its research. RTOGF is the successor of the National Cancer Institute(NCI)-funded Radiation Therapy Oncology group that was organized in 1968 as a national clinical cooperative group for the purpose of conducting multicenter radiation therapy research and clinical investigations. It was part of the NCI-funded cooperative group program and managed by the American College of Radiology (ACR) from 1971 until 2014. During that time, it activated over 500 protocols, accrued more than 110,000 patients to cooperative group studies, and published over 1,000 papers reporting the results of its findings. RTOGF has continued its close relationship with ACR to engage in clinical trial research collaborations with a variety of industry partners and participates in Federal grant-funded research through its leadership in the NCI National Clinical Trial Network group NRG Oncology.


Participate in RTOG Research

To participate as an RTOG study investigator, your organization must be part of the RTOG Foundation network. Patients who wish to participate in a study must be under the care of an RTOG participating investigator. For additional information, email info@rtog.org or call 1-215-574-3173.

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