A Safety Lead in Single Arm Phase II Study for Image Guided Personalized Ultra-fractionated Stereotactic Adaptive Radiotherapy (PULSAR) for Treatment of Metastatic Cervical Cancer

The poor outcomes and local morbidity of disease in metastatic cervical cancer, despite evolution in systemic therapy, argues for novel strategies to improve outcome. Improvements in disease control, prevention of morbid local symptoms and even survival have been demonstrated when treating the primary in other cancer types 3,4 Preliminary retrospective data have associated primary site RT with survival benefit in metastatic cervical cancer, but these did not use standardized RT approaches or consider integration with newer systemic therapies28,29. It thus is hypothesized that primary site RT in cervical cancer may achieve similar improvements, but must balance the specific toxicity risks of this disease site and systemic therapy context. Namely, a successful approach must minimize number of treatments to avoid patient inconvenience and systemic therapy interruption, minimize toxicity, and add potential for enhancing systemic disease control. To do this, this study proposes to use PULSAR, implemented by adaptive MRI-guided SAbR in 5 treatments, to deliver primary site cervical RT with ongoing standard systemic therapy. This approaches minimizes treatment visits, doesn't interrupt systemic therapy, uses response-adapted highly conformal RT with advanced image guidance to minimize toxicity risk, and provides potential for improving efficacy of immunotherapy in those receiving it.