Personalized Radiation Therapy (PULSAR) for the Treatment of Patients with Extensive-Stage Small Cell Lung Cancer or Brain Metastases, the PRISM Trial
This clinical trial studies the safety and side effects of personalized radiation therapy (personalized ultrafractionated stereotactic ablative radiotherapy [PULSAR]), and how well it works in treating patients with extensive-stage small cell lung cancer (ES-SCLC) or cancer that has spread from where it first started (primary site) to the brain (brain metastases). Patients diagnosed with ES-SCLC and prescribed radiation therapy (RT) most often receive treatment targeted to the initial extent of disease, without accounting for changes that may occur in tumor target shape/size/sensitivity or patient tolerance. Additionally, RT is typically given in a continuous daily course over several weeks after completion of chemotherapy and immunotherapy (i.e., "chemoimmunotherapy"), with little time interval to evaluate for response to treatment. This results in some patients receiving more dose or a bigger radiation field than needed, while others may have achieved better disease control with radiation dose-escalation. This also may affect the effectiveness of these treatments attempting to recruit the immune system against the cancer, called immunotherapy. This trial seeks to space out radiation treatments into three larger doses over ~2 months aligned with infusions of chemoimmunotherapy. These treatments will be given with high precision using a technique called “stereotactic body radiation therapy” or SBRT. SBRT treatments will be performed on specialized ‘adaptive’ RT platforms that incorporate imaging during these sessions to allow the physician to change the shape and size of the tumor target according to response to prior treatment. Giving SBRT using PULSAR may reduce the radiation dose and side effects to normal organs, while potentially improving immune system responses against the cancer. Patients diagnosed with cancer and brain metastases who are prescribed RT most often receive treatment targeted to the initial extent of disease, without accounting for changes that may occur during treatment in tumor shape/size/sensitivity or patient tolerance. This results in some patients receiving more dose or a bigger radiation field than needed, while others may have achieved better disease control with higher dose delivery. This is relevant in the treatment of brain metastases with a technique called fractionated stereotactic radiotherapy (fSRT), which is delivered across 5 sessions. fSRT is given in 5 fractions broken into 2 “pulses” with about a month between the pulses. The second pulse will be adjusted, as needed, based on imaging after the first pulse. This trial seeks to use magnetic resonance imaging (MRI) during treatment to adjust the treatment dose and target size as it responds to treatment. The goal is to characterize how often treatment can be skipped or reduced in the case of excellent initial response, thereby potentially reducing side effects.