Real-world Use of Radiation for Newly Diagnosed Brain Metastases in Patients With ALK-positive Lung Cancer Receiving First-line ALK Inhibitor

Purpose: Management paradigms now allow for systemic targeted drugs before central nervous system (CNS)-directed radiation therapy (RT) in selected asymptomatic patients with non-small cell lung cancer (NSCLC) and brain metastases (BM). We aimed to quantify how novel targeted agents with improved CNS activity, such as second-generation anaplastic lymphoma kinase (ALK) inhibitors (eg, alectinib), might affect the role of CNS-directed RT. Methods and Materials: This retrospective, observational, real-world, patterns-of-care study used a nationwide, electronic, health record-derived, de-identified, longitudinal database. A random sample of patients with ALK+ advanced NSCLC and BM on first-line ALK-inhibitor monotherapy between January 1, 2014 and August 31, 2019 were included. Using an index date of the first instance of BM, the outcome was brain-directed local treatment within 4 months. Trends over time were reported and tested using multivariable modified Poisson regression with robust error variance, including an indicator during or after 2017 (when alectinib was approved). Results: Of the 352 included patients, 146 had BM. In addition, 104 patients received CNS-directed local therapy, and 42 did not. The majority of patients (89.4%) were treated with RT alone. Of those receiving RT, stereotactic radiosurgery monotherapy was the most common (53%), followed by whole brain RT alone (39%). On multivariable analysis, patients who had their first BM during or after 2017 had a decreased rate of receiving local BM treatment versus those before 2017 with an adjusted incidence rate ratio of 0.63 (95% confidence interval [CI], 0.41-0.95; P = .026). We found no change in the proportion of BM treated with whole brain RT during or after 2017 versus before (adjusted incidence rate ratio: 0.70; 95% CI: 0.24-2.06; P = .517). Conclusions: We found decreasing use of CNS-directed RT in patients with NSCLC with new BM on first-line ALK inhibitors. Clinical outcomes for these patients require continued investigation, because physicians may become increasingly comfortable deferring upfront local therapy for BM in lieu of novel targeted agents with improved CNS activity.