Amsterdam University Medical Center successfully completed the first prospective clinical trial of MRI-guided radiation therapy (MRgRT) in patients with localized prostate cancer supporting industry sponsor ViewRay, Inc. (VRAY). The roust study of clinician and patient reported outcomes demonstrated zero CTCAE v4 grade 3 or higher gastrointestinal (GI) and genitourinary (GU) toxicity and even lower incidence of grade 2 toxicity than investigators hypothesized. The trial represents one of the first prospective trials to study SBRT in a mix of intermediate-and high-risk prostate cancer patients, a challenging patient population to treat.
The study results are published in the American Society for Radiation Oncology. Researchers from Amsterdam University Medical Center enrolled 101 patients with intermediate-or high-risk prostate cancer in a prospective phase II clinical trial. All patients received MRgRT in five fractions of 7.25 Gy to the target volume using on-table adaptive techniques. The trial did not use implanted markers or tissue spacers because treatments were delivered under MRI-guidance, thereby eliminating an invasive procedure, potentially associated complications, and implementation costs.
Results at three months showed that no early CTCAE v4.0 grade 3 GU or GI toxicity was observed, and the maximum cumulative grade 2 early GU and GI toxicity measured by any symptom at any study time point was 23.8% (study hypothesis 40%) and 5.0% (study hypothesis 15%). These results were obtained in a complex clinical cohort (59.4% high-risk patients) and are comparable to what would be typically observed in lower-risk populations, pointing to the potential benefits of MRI-guided SBRT in this higher-risk group.
Moreover the low incidence of early GI toxicity, despite the inclusion of the base of the seminal vesicles in 96% of patients, illustrates the benefit of MR-guidance and on-table adaptive re-planning. This technology facilitates smaller treatment margins while minimizing damage to surrounding tissue and critical structures, such as urethra, rectum, and bladder. The publication noted that incontinence was uncommon, reported by only 4% of participating patients at the end of the MRgRT and decreasing over time.
Clinical Investigator Comments
Anna Bruynzeel, MD, PhD, Radiation Oncologist at Amsterdam UMC reported, “SBRT offers significant promise in the treatment of prostate cancer. Our clinical trial takes that a step further in showcasing its value in patients with intermediate-and high-risk disease, with a focus on evaluating associated toxicities and quality of life outcomes.” She continued, “We see a lower incidence of GI and GU toxicity with MR-guidance as compared to similar SBRT prostate cancer studies. The results reinforce the value of MRIdian’s real-time on-table adaptive treatment with automatic beam gating for prostate patients.
Clinical Sponsor: ViewRay
ViewRay (VRAY) designs, manufacturers and markets MRIdian® the world’s first MRI-guided radiation therapy system that can image and treat cancer patients simultaneously. MRIdian addresses key limitations of existing external-beam radiation therapy technologies because it integrates MRI technology, radiation delivery, and proprietary software to locate, target, and track the position and shape of soft-tissue tumors while radiation is delivered. Real-time MRI-imaging clearly defines the targeted tumor from the surrounding soft tissue and other critical organs during radiation treatment allowing the system to deliver radiation to the tumor accurately while delivering less radiation to healthy tissue. MRIdian’s targeting accuracy combined with improved tumor visibility and accurate dose recording means clinicians can treat patients who may not previously have been considered radiation therapy candidates. ViewRay believes MRIdian may improve the safety and efficacy of radiation therapy, potentially leading to improved patient outcomes with reduced side-effects from off-target radiation delivery.
Amsterdam University Medical Center
Amsterdam UMC employs more than 15,000 professionals, treating over 350,000 patients a year at both its sites–AMC and VUmc. Working towards a future in which illnesses are prevented and the best treatment made available to all patients, Amsterdam UMC has developed new methods for diagnostics and treatment together with professionals from other renowned national and international institutions. The institute’s main focus is on complex patient care and highly-specialized treatment of rare medical conditions. Amsterdam UMC teaches and trains thousands of young people to become doctors, specialists or nurses. Its researchers are clustered in eight research centers so that the institute can achieve its ambition of executing international, cutting-edge research. At Amsterdam UMC, AMC and VUmc are working together on academic patient care, scientific research and teaching and training.
Anna Bruynzeel, MD, PhD, Radiation Oncologist at Amsterdam UMC