By Amanda Walker, MD
The field of medical oncology is undergoing a remarkable transformation. Cancers that were once considered death sentences, such as multiple myeloma and metastatic melanoma, are turning into chronic diseases due to the use of novel targeted systemic therapies. Immunotherapy, heralded as a “game changer” in oncology, is altering the natural history of certain malignancies, checkpoint inhibitors are making their way into front-line management and CAR-T cell therapy has demonstrated durable responses in patients with refractory hematologic malignancies.
The field of radiation oncology is also undergoing a remarkable transformation. Improved radiation delivery techniques allow radiation oncologists to more precisely target the tumor and spare normal tissue. Treatment times are shortening due to the delivery of higher doses per fraction, and radiation fields are shrinking. A number of clinical trials are investigating the role of stereotactic body radiation therapy (SBRT) in patients with oligometastatic disease, and novel image guidance techniques allow adaptive radiation treatment planning in real time, providing yet another tool to optimize the therapeutic index of radiation therapy.
While both medical oncology and radiation oncology have made great strides independently of one another, very little has changed in terms of the systemic therapies that we use in combination with radiation. Over the past 10 years, the Office of Hematology and Oncology Products at the U.S. Food and Drug Administration (FDA) has approved more than 200 new drug and biologic licensing applications, but none of these approvals were for use in combination with radiation therapy. The reasons for this discrepancy are complex and multifactorial, including limited regulatory precedent and perceived challenges in trial design and data collection with radiation.
Recent studies have shown that radiation therapy can work synergistically with immunotherapy agents to induce potent antitumor immune responses. A number of mechanisms have been postulated including increased expression of negative immune regulators, increased antigen presentation and other modifications of the adaptive immune response with radiation. Other targeted molecular therapeutics, such as inhibitors of DNA repair enzymes and growth factors, have a strong preclinical rationale for use in combination with radiation therapy based on their mechanism of action, yet very few agents have successfully moved from the lab into clinic.
Given the enormous potential for drug-radiotherapy combinations to improve meaningful clinical outcomes, the American Association for Cancer Research (AACR), ASTRO and the FDA are co-sponsoring the Clinical Development of Drug-Radiotherapy Combinations Workshop to address the lack of development in this area. The workshop takes place on February 22–23 at the Hyatt Regency Hotel in Bethesda, Maryland, and will bring together key stakeholders from around the world, including industry, regulatory agencies, patient advocates and academic oncologists. The goal is to engage in robust discussions with a focus on the most practical aspects of drug development.
Radiation will remain a fundamental pillar of cancer treatment for the foreseeable future, but until every cancer patient treated with radiation therapy is cured, there is still work to do. We are reaching the limits of our siloed approach to advancing the field. Now is the time to break down the silos and join forces with our colleagues to improve the lives of our patients. Join us at the workshop next month so we can start this important work.
What questions do you have about developing effective drug-radiation therapies? Tell us in the comments.
Amanda Walker, MD, is associate director (acting), Oncology Center of Excellence and medical officer, Division of Oncology Products 1, Office of Hematology and Oncology (OHOP), Center for Drug Evaluation and Research (CDER) at the FDA.