Local control and leptomeningeal disease after resection and GammaTile brachytherapy for newly diagnosed brain metastases: results from a prospective registry

Local failure and leptomeningeal disease (LMD) are both poor outcomes that can occur after resection and post-operative radiosurgery for newly diagnosed brain metastases (BM). There is increasing utilization of collagen-embedded Cesium-131 brachytherapy (GammaTile®) as a method of providing immediate adjuvant radiation therapy. Post-operative LMD rates following GammaTile implantation for newly diagnosed BMs has yet to be reported. The objective was to evaluate the incidence of LMD rates, local control (LC), and survival following resection and GammaTile for newly diagnosed BMs. An ongoing, multicenter, prospective, observational Phase IV non-interventional registry (NCT0442738) was queried to analyze rates of LMD following surgical resection of newly diagnosed BMs. Following resection and GammaTile implantation, we evaluated LMD rates, LC, and overall survival (OS). The Kaplan-Meier method was used to analyze time-to-event outcomes. Fifty-one patients with 55 BMs were analyzed. The median follow-up was 12.4 months. The majority of BMs were in the supratentorial brain (87.3%). Four patients (7.8%) experienced LMD, 3 pachymeningeal and 1 classical. The 3-, 6-, and 12-month LMD-free rates were 97.4%, 94.1%, and 88.5%, respectively. The 12-month LC was 92.3%, and the 12-month OS was 49.0% with a median OS of 11.0 months. In this prospective registry study, GammaTile at the time of resection of newly diagnosed BMs was associated with high rates of tumor control and modest rates of LMD. As the trial registry continues to accrue, further data will continue to shed light on variables associated with outcomes.