A Master Trial Assessing the Technical Feasibility of First-In-Human Real-Time Image Guided Radiation Therapy Methods

Real-time IGRT is a master trial to assess the technical feasibility of first-in-human real-time image guided radiation therapy methods.

Real-time image guided radiation therapy (IGRT) methods image the cancerous tumour in real-time, enabling the treatment beam to focus its destructive energy on the patient's cancer, not their healthy tissue. Using a real-time IGRT method available on scarce $10M MRI-guided radiation therapy devices, has halved the incidence of acute grade 2 or greater genitourinary (GU) toxicity for prostate cancer patients. However, \>95% of radiotherapy is given on standard $3M devices. The halving in GU toxicity was confirmed in a study from Memorial Sloan-Kettering using combined kilovoltage and megavoltage guidance. This clinical benefit has led to a global demand: over 70% of centres want better real-time IGRT methods but are limited by resources and capacity. The tipping point is the implementation of real-time IGRT methods on standard devices. The Real-time IGRT trial addresses this unmet need by assessing an array of real-time IGRT methods.

To establish real-time IGRT methods, the University of Sydney partner hospitals and cancer centres have been working together across many different cancers, to create a database of images that have been, and are being, used to develop real-time IGRT methods. This development has led to the creation of LEARN, the Learning Environment for Artificial Intelligence in Radiotherapy New Technology, and the associated image acquisition study (https://clinicaltrials.gov/study/NCT05184790). The LEARN study looks at images retrospectively, meaning patients do not directly benefit from their involvement. To achieve benefit for study patients, and ultimately in broader practice, prospective implementation of real-time IGRT methods is required. This umbrella protocol, Real-time IGRT, enables a framework for the safe implementation and evaluation of real-time IGRT methods. Patient dosimetric and geometric targeting benefits will be measured, with the information acquired used to further improve the safety and accuracy of real-time IGRT methods.

The technologies being developed are numerous, covering different individual and combinations of imaging methods (surface, kV, MV), are applicable to different cancer sites, use marker and markerless approaches, and track one or more targets and normal tissues. To perform a feasibility study for each single innovation and for each single tumour site is time consuming when using a standard trial protocol. Instead, a master protocol trial comprises one general protocol that includes multiple subgroups and/or multiple interventions. Given this large variety of methods to be tested, a master protocol trial is the most efficient to maximise the safe testing of technologies, and to cease or pause technologies that do not meet the clinical requirements.

The master protocol trial aims to increase efficiency in terms of trial infrastructure and protocol administration to accelerate development of technical innovations in radiation oncology, meaning that patients benefit from the technologies earlier. By including multiple parallel cohorts, the protocol will accelerate the technical development of real-time IGRT methods and the evidenced-based introduction of real-time IGRT methods into clinical practice. This approach reduces the burden on the HREC, the sponsor and the participating centres.