The first patients have been dosed in the phase 2 PRECISION study investigating a novel 3-fraction regimen of stereotactic body radiotherapy (SBRT) for patients with low- to intermediate-risk localized prostate cancer, Micropos Medical announced this week.
The Edinburgh Cancer Centre in Scotland has begun treating patients within the framework of this innovative trial, which aims to further streamline prostate cancer radiotherapy while maintaining efficacy and potentially reducing side effects.
Building on PACE-B Success
The PRECISION study (NCT06117059) was initiated following promising results from the phase 3 PACE-B trial published in the New England Journal of Medicine in 2024. PACE-B demonstrated that 5 fractions of SBRT was noninferior to conventional or moderately hypofractionated radiotherapy regimens that required 20-40 treatment sessions.
"The goal of the PRECISION study is to ensure that treatment with 3 radiation doses does not lead to greater side effects than those observed in the PACE-B study. I am confident that we can demonstrate effective cancer treatment with less side effects," said Professor Duncan B. McLaren, MBBS, of the Edinburgh Cancer Centre, who leads the study.
Study Design and Patient Population
The trial plans to enroll 100 patients across multiple clinical sites in the United States and Europe. Participants will receive three fractions of SBRT delivered over three consecutive days—a significant reduction from the current standard of five fractions.
Eligible patients must have low- to favorable intermediate-risk prostate cancer according to National Comprehensive Cancer Center criteria. Additional inclusion requirements include:
- Prostate volume under 80cc
- International Prostate Symptom Score (IPSS) below 20
- Qmax above 10cc per second
- Urinary residual less than 150 mLs
Exclusion criteria include previous transurethral resection of the prostate (TURP), hip replacements, prior pelvic radiotherapy, T3a disease or above, Gleason score of 7, or PSA greater than 20 ng/mL.
Advanced Technology for Precision Treatment
A key component of the PRECISION study is the use of the RayPilot Tumor Tracking System, which enables real-time monitoring of organ movement during treatment. This technology aims to improve targeting accuracy and potentially reduce treatment-related side effects.
"Our customers are interested in developing and improving healthcare, always with patient quality of life in focus," said Thomas Lindström, MD at Micropos Medical AB, the company behind the RayPilot System. "At the same time, healthcare providers across the Western world are striving to reduce treatment times and enhance both quality and efficiency."
Outcome Measures and Timeline
The primary outcome measures of the PRECISION study include urinary and bowel toxicity, assessed using Radiation Oncology/Toxicity Grading (RTOG) and Common Terminology for Adverse Events criteria. Secondary endpoints include IPSS, erectile function scores, and bowel function scores.
According to Micropos Medical, initial data from the study are expected within 1-2 years, with final results to be reported after an additional 5 years of follow-up.
PACE-B: The Foundation for Further Innovation
The PACE-B trial that inspired PRECISION was a phase 3, open-label study that enrolled 874 patients with localized prostate cancer. Patients were randomized to receive either 5-fraction SBRT (36.25 Gy) or conventional/moderately hypofractionated radiotherapy (78 Gy in 39 fractions or 62 Gy in 20 fractions).
At a median follow-up of 74 months, the 5-year incidence of freedom from biochemical or clinical failure was 95.8% in the 5-fraction SBRT arm versus 94.6% in the standard radiotherapy arm, demonstrating noninferiority.
While the efficacy was comparable, there were some differences in toxicity profiles. The cumulative incidence of grade 2 or greater genitourinary toxicity was higher in the 5-fraction SBRT arm (26.9% vs 18.3%), while late gastrointestinal toxicity was similar between groups (10.7% vs 10.2%).
Potential Impact on Patient Care
If successful, the PRECISION study could establish a new standard of care that significantly reduces treatment burden for prostate cancer patients while maintaining efficacy and potentially improving side effect profiles.
"This study could contribute to such progress, benefiting all stakeholders—healthcare providers reduce costs while improving care, and patients gain a better quality of life," Lindström added.
The streamlined approach of just three treatment sessions represents a dramatic improvement from traditional radiotherapy regimens that required patients to undergo daily treatments for 7-8 weeks. This reduction in treatment time could improve patient convenience, reduce healthcare costs, and increase treatment capacity at radiotherapy centers.
