(UroToday.com) The American Urologic Association (AUA) annual meeting included a late-breaking abstract session including a presentation by Dr. Sarah Welsh discussing translational results of the NAXIVA trial, a phase 2 neoadjuvant trial of axitinib for reducing the extent of venous tumor thrombus in clear cell renal cell cancer with venous invasion. Venous tumor thrombus extension occurs in 4-15% of cases of renal cell cancer, and although surgery is performed with curative intent, mortality is high (5-15%). The concept of neoadjuvant targeted therapy to downstage venous tumor thrombus prior to extirpative surgery is appealing in order to reduce the extent of the venous tumor thrombus surgery, and potentially reduce morbidity and mortality of the operation. The NAXIVA trial provided the first level II evidence in this patient group, assessing the response of venous tumor thrombus to axitinib. The primary endpoint, first presented at GU ASCO 2021, of the percentage of evaluable patients with an improvement in venous tumor thrombus according to the Mayo classification was positive at 26.58%. Additionally, 35.29% of patients had a change in the surgical approach to a less invasive option. Median percent reduction in venous tumor thrombus height was 21.49%. Response rate (RECIST) was 61.90% with stable disease, 14.29% with a partial response, and 9.52% with progressive disease. In this presentation, Dr. Welsh and colleagues presented the results of translational studies examining the role of the tumor microenvironment and response to axitinib.