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VPT Advisory Board: Pushing the Limits of Proton Therapy

Translational medicine, clinical indications, and adaptive therapy were just a few of the important topics discussed at Varian’s 2016 Particle Therapy Advisory Board Meeting.

Composed of radiation oncologists and physicists from around the world, the 20-member advisory board draws on their collective experience to provide clinical insights on particle therapy.  The diverse group includes leaders from both academic and private clinics who utilize the equipment of all major proton vendors.

The format of the meeting provided a unique opportunity for in-depth discussions to address the following topics critical to the development of proton therapy.

 

Radiobiology: RBE, Biomarkers, and Clinical Trials

Renate Parry, PhD, Varian Medical Systems, Director of Translational Medicine & Radiobiology, spoke about the future of dose painting and relative biological effectiveness (RBE).

“Varian recognizes the opportunity for incorporating new developments in biology to advance patient treatment and is supporting translational research at several prominent clinical institutions,” said Dr. Parry. “The board provided valuable feedback on areas in which we should focus our research, including genomics-based biomarkers for patient stratification and drug-radiation combination approaches to widen the therapeutic window. One of our key objectives is to identify the unique radiobiological effects of protons and photons when used in combination with drugs or immunotherapy treatments.”

In addition, Varian offered a tour of their radiobiology laboratories. The state-of-the art laboratories are equipped to conduct translational research activities ranging from cultivating and irradiating mammalian cells, conducting molecular biology and genomics studies, performing biochemical analysis, and characterizing cells and tissues by digital microscopy and flow cytometry.

“I am impressed that Varian is taking on the initiative to incorporate biology into their research and I think this is an important step that differentiates them in this space,” said Dr. John Perentesis, director, Division of Oncology and Cancer Programs at Cincinnati Children’s Hospital.

 

Expanding the Indications for Intensity Modulated Proton Therapy

The advisors also reviewed the recommended indications for proton therapy, developed in 2015 by ASTRO. “Medically necessary” indications comprised Group 1 while Group 2 disease sites were deemed as possible indications that needed continued clinical evidence-development and clinical effectiveness analyses for the appropriate use of proton therapy. The advisory board focused on how to generate the right data to expand the list of disease sites on Group 2 to ensure diseases that respond well to proton therapy are included, such as breast cancer – left breast cancer in particular.

Dr. Dee Khuntia, vice president of Medical Affairs at Varian Medical Systems, and a practicing radiation oncologist commented, “It is very clear that the number of diseases to which protons provide value will continue to increase, and as this happens, we will see proton therapy continue to expand beyond just the large tertiary academic cancer programs.”

 

Innovations in Treatment Planning to Advance Adaptive Proton Therapy

The scope of the discussion included several new tools Varian is developing to help enable advancements in adaptive proton therapy. The board helped to prioritize the features that would be most effective, including the Velocity™ adaptive dose tracking tools for offline adaptive therapy.  Also, Varian received feedback on how RapidPlan™ can be utilized to expand proton therapy research.

Dr. James Metz, MD, chair of radiation oncology at the Perelman School of Medicine, University of Pennsylvania, highlighted the need for rapid soft tissue imaging for adaptive therapy with spot scanning. “In order to take the necessary steps to perform online adaptive IMPT, we first need to have fast imaging capability that allows for confidence in daily dose calculation along with the capability to adapt or re-optimize efficiently, when needed,” said Dr. Metz.

This prompted a discussion on next generation tools that will allow for treatment monitoring and dose tracking. The ability to generate a synthetic CT based off of the daily cone beam CT in combination with Monte Carlo dose calculation will allow for the most accurate dose tracking available.  This in combination with scripting capabilities will also allow for automating and streamlining the dose tracking workflow so that clinicians can readily have information needed to decide when and how to re-optimize.

Some of the advisors will help provide critical clinical information to empower knowledge based planning. Prof. Antony Lomax, chief medical physicist at the Paul Scherrer Institut in Switzerland stated: “We are looking forward to working with the new Velocity tools to study offline adaptive workflows.  We also are excited about working with collaborators on building IMPT RapidPlan models for the use of decision support and plan quality assessment.”

The discussion on these critical topics will help Varian focus the proton therapy strategy to most benefit current and future customers and their patients.  “This Advisory Board provides Varian a unique opportunity to hear directly from key opinion leaders in the radiation oncology field on a variety of topics that will impact our direction and how we expand proton therapy access around the world.  I am grateful for their insight, frank discussions and comradery, and look forward to working with them throughout the year,” said Dr. Moataz Karmalawy, vice president and general manager of Varian's Particle Therapy division.