The Cincinnati Children’s / UC Health Proton Therapy Center has begun the world’s first clinical trial of FLASH radiation therapy for cancer.

FLASH uses radiation delivered at ultra-high speeds up to 1,000 times faster than what is used clinically today. Multiple preclinical research studies at the Proton Therapy Center at Cincinnati Children’s and other centers around the world have investigated this novel technology and its effect on malignant and healthy tissues in animals for several years.

Now the FAST-Bone (FeAsibility STudy of FLASH Radiotherapy for the Treatment of Symptomatic Bone Metastases) will enroll 10 adult patients with metastatic bone cancer. The patients will receive FLASH therapy in a single treatment session, with less than one second of radiation exposure. Endpoints will include the evaluation of clinical workflow feasibility, treatment-related side effects and efficacy of treatment, which will be assessed by measuring trial participants’ pain relief.

The Proton Therapy Center, operated by Cincinnati Children’s and University of Cincinnati Medical Center, is one of only 31 proton therapy centers in the United States. It houses the most versatile proton research facility in the world, along with two state-of-the-art therapy rooms. The center’s 90-ton cyclotron has been providing next-generation pencil beam scanning proton therapy to pediatric and adult patients since 2016, with more than 4,000 proton treatments each year for more than 30 types of cancer.

The FAST trial was designed by experts at Cincinnati Children’s and the University of Cincinnati Medical Center.

“Our preclinical FLASH research indicates there’s a potential for reducing toxicity associated with conventional radiation therapy techniques when treating at ultra-high dose rates,” says John C. Breneman, MD, medical director of the Proton Therapy Center and principal investigator of FAST-Bone. “This new study will add to a growing body of data necessary to advance our understanding of this promising technology.”

Preclinical FLASH studies at Cincinnati Children’s focus on increasing tumor efficacy and reducing side effects for brain tumors, lung cancer, and cancers of the head and neck. Preliminary data from one preclinical study, led by Tanya Kalin, MD, PhD, showed that FLASH demonstrates a double benefit compared to conventional proton treatments. In addition to killing lung cancer more efficiently, it activates an immune system response to lung cancer.

“Delivering an ultra-high dose rate of protons seems to trigger a different biological mechanism that kills tumors but spares healthy tissues, and our researchers are trying to understand that,” says Anthony Mascia, PhD, director of medical physics at the Proton Research Center. “Conventional proton therapy is good at creating superior dose distribution, but FLASH moves the ball further to the goal line. It potentially achieves as good a physical dose distribution while sparing healthy tissue further with the FLASH effect.”