Abstract No. 31 Clinical Efficacy of Pressure-Enabled Transarterial Embolization of Hypovascular, Treatment-Refractory Metastases

To evaluate the technical success and treatment response of transarterial embolization for treatment-refractory, hypovascular metastatic tumors using pressure-enabled delivery. This single-center, retrospective study evaluated outcomes following "bland" microsphere embolization of treatment-refractory hypovascular metastatic tumors. Records were collected from the institutional database with procedures dating from January 2021 to July 2023. Technical success was defined as the ability to perform transarterial embolization with the TriNav microcatheter from the target vessel(s) to complete stasis. Treatment response was evaluated on a per-lesion basis using RECIST v1.1. 28 patients and 32 procedures to treat 80 tumors (Table 31.1) were included. A variety of tumor histologies were included in the study cohort, the majority of which are notable for developing hypovascular metastases and for which embolization is not commonly performed. 93%, 82%, and 46% of patients were previously treated with chemotherapy, surgery, and radiotherapy, respectively. Two patients had previously undergone aborted embolization attempts using a standard end-hole microcatheter due to the lack of angiographic visualization of the target lesions. Technical success for embolization using the TriNav microcatheter was 100%. The most common site of treated metastases included the liver (88%), axial skeleton (9.4%), and adrenal gland (3.1%). The median artery caliber from which embolization was performed was 2.1 mm (range 1.2-4.1 mm), while the median tumor size was 5.7 cm (0.9-15.3 cm). Local tumor progression-free survival rates at 1 month, 6 months, and 1 year were 94%, 80%, and 70%, respectively. Post-treatment imaging showed a significant decrease in tumor attenuation following embolization based on Hounsfield units (P < 0.001). There were two complications (6%), one major and one minor. Pressure-enabled delivery provides durable treatment responses for treatment-refractory hypovascular metastatic tumors.