Single Institutional Experience of Neoadjuvant Therapy Prior to Planned Surgical Resection for Complex or Locoregional Renal Cell Carcinoma.

439 Background: Cytoreduction via systemic neoadjuvant therapy is an emerging investigational strategy in localized renal cell carcinoma (RCC). We analyzed our single institutional experience with neoadjuvant therapy. Methods: ingle institutional retrospective analysis of patients with T2-T3N0M0 RCC. Patients received confirmatory biopsy for clear cell histology prior to receipt of systemic therapy and underwent radical (RN) or partial nephrectomy (RN). Neoadjuvant therapy consisted of tyrosine kinase inhibitor (TKI) or Immuno-oncology (IO) therapy and/or combination (TKI-IO). Neoadjuvant therapy was given prior to planned partial nephrectomy for complex renal mass with imperative indications for nephron preservation and prior to planned radical nephrectomy in setting of locoregional disease with possible adjacent organ or great vessel involvement where multiorgan system resection was risked. Primary outcome was percentage cytoreduction comparing pre-treatment and post treatment mass size. Secondary outcome included partial response (PR) rate as per RECIST criteria, negative surgical margins, and lack of major 30-day complications (Clavien ≥3). Comparative analysis was conducted for outcomes between groups for overall survival (OS), cancer specific survival (CSS), and progression free survival utilizing Kaplan Meier Analyses (KMA). Results: A total of 50 patients (33 TKI, 17 IO + TKI-IO) were analyzed (median follow up 31.1 months). Overall PR and cytoreduction rates were 18.0% and 4.2%. No differences in tumor size were noted (7.7 vs. 10.4 cm, p= 0.08). There were no differences in % cytoreduction (12.2 vs. 11.8, p=0.13) and % PR (17.8% vs. 30.7%, p=0.73) between the groups. Overall, 18 patients and 30 patients underwent PN and RN, respectively. 30-day major complication rate was 28.0% and 20.5% was PSM rate. KMA revealed 3-year OS, CSS and PFS of 74%, 75%, and 14%. No differences were noted between TKI and IO/IO-combination groups for PFS (16.7% vs. 10.0%, p=0.45), CSS (70.9% vs. 93.3%, p=0.20), and OS (68.3% vs. 93.3%, p=0.06). Conclusions: Neoadjuvant therapy prior to surgery for complex and locoregional disease resulted in cytoreduction and was associated with acceptable safety, surgical quality, and short term oncological outcomes. Further investigation is requisite to delineate role of neoadjuvant therapy in localized RCC.