Results from FAST-01 (FeAsibility Study of Flash Radiotherapy for the Treatment of Symptomatic Bone Metastases) -- which was conducted at the Cincinnati Children's/University of Cincinnati Medical Center Proton Therapy Center -- were also released October 23 in JAMA Oncology and show that ultrahigh dose rate proton Flash therapy is feasible in a clinical setting, according to the firm.

The trial included 10 participants who underwent palliative Flash therapy for bone metastases in their extremities. A modified version of Varian's ProBeam particle accelerator delivered the entire radiation therapy dose in less than a second.

Eight of 12 sites of pain (67%) in the study participants showed pain relief, and six of the 12 sites had a complete response of no pain. There were no treatment-related technical issues or delays, and all adverse events were mild and "consistent with those expected from conventional radiotherapy," Varian said.