Avoiding Radiation Therapy Due to Intracranial Response to Chemotherapy, Targeted Therapy and/or Immuno-ONcology Therapy for Brain Metastases: Pilot Pragmatic Trial

This pilot pragmatic trial evaluates the feasibility of avoiding radiation therapy in patients with brain metastases who demonstrate an intracranial response to systemic therapy-including immunotherapy, targeted therapy, and/or chemotherapy. The study will prospectively enroll 45 patients, divided into two cohorts: 30 with non-small cell lung cancer (NSCLC) receiving immunotherapy, and 15 with brain metastases from other solid tumors. Eligible participants must have at least one brain metastasis not planned for radiation or surgery and must be initiating or planning to initiate a systemic therapy regimen expected to penetrate the blood-brain barrier and achieve intracranial activity. All patients will undergo a re-evaluation brain MRI 4-8 weeks after initiating systemic therapy. If lesions are stable or regressing, patients will continue surveillance without radiation. If progression is noted, standard-of-care radiation may be administered at the discretion of the treating physician. The primary objective is to assess 6-month radiation therapy-free survival (RTFS) in NSCLC patients based on PD-L1 expression status. Secondary endpoints include intracranial progression-free survival, overall survival, radiation necrosis rate, and quality of life. This study seeks to inform future trial design and identify patients who may safely avoid brain radiation.