Genomic Signature for Initial Brain Metastasis Velocity (iBMV) in Non-Small-Cell Lung Cancer Patients: The Elusive Biomarker to Predict the Development of Brain Metastases?

<b>Background/Objectives</b>: No prior studies have attempted to identify a biomarker for initial brain metastasis velocity (iBMV), with limited studies attempting to correlate genomic data with the development of brain metastases. <b>Methods</b>: Patients with non-small-cell lung cancer (NSCLC) who underwent next-generation sequencing (NGS) were identified in our departmental database. iBMV was calculated by dividing the number of BMs by the interval of time between primary cancer and BM diagnosis. Two-sample <i>t</i>-testing was used to identify mutations statistically associated with iBMV (<i>p</i> < 0.1). A value of +1 was assigned to each mutation with a positive association ("deleterious genes"), and a value of -1 to each with an inverse association ("protective genes"). The sum of these values was calculated to define iBMV risk scores of -1, 0 and 1. Pearson correlation test was used to determine the association between iBMV risk score and calculated iBMV, and a competing risk analysis assessed for death as a competing risk to the development of BMs. <b>Results</b>: A total of 312 patients were included in the analysis, 218 of whom (70%) developed brain metastases. "Deleterious genes" included ARID1A, BRAF, CDK4, GNAQ, MLH1, MSH6, PALB2, RAD51D, RB1 and TSC1; "protective genes" included ARAF, IDH1, MYC, and PTPN11. iBMV risk scores of 1, 0 and -1, predicted an 88%, 61% and 65% likelihood of developing a BM (<i>p</i> < 0.01). A competing risk analysis found a significant association between iBMV risk scores of 1 vs. 0 and 1 vs. -1, and the likelihood of developing a BM using death as a competing risk. Overall survival (OS) at 1 and 2 years for patients with iBMV risk scores of 1, 0 and -1 was 72% vs. 84% vs. 85% and 46% vs. 69% vs. 70% (<i>p</i> < 0.02). <b>Conclusions</b>: Development of a genomic signature for iBMV via non-invasive liquid biopsy appears feasible in NSCLC patients. Patients with a positive iBMV risk score were more likely to develop brain metastases. Validation of this signature could lead to a biomarker with the potential to guide treatment recommendations and surveillance schedules.