Potential impact of prior high-dose IL-2 on the outcomes of sunitinib (Su) treatment (tx) in patients (pts) with metastatic renal cell carcinoma (mRCC).

494 Background: Targeted txs are the tx of choice in most mRCC pts. However, HDIL2 which may produce durable responses in a small percentage of cases, is still an option in carefully selected pts. While the effect of prior HDIL2 on the outcome of targeted txs in mRCC pts is poorly defined, a recent single center report (Birkhäuser FD, Cancer J 2013) revealed an improved disease-specific survival in pts treated with prior HDIL2. We aimed to study the effect of prior HDIL2 tx on outcome of mRCC pts treated with sunitinib. Methods: Records from 302 mRCC pts treated with Su from 2004 to 2013 in 9 centers across 2 countries were retrospectively reviewed. We compared the response rate, progression free survival (PFS), and overall survival (OS), between post HDIL2 pts (n=27) and individually matched tx naïve pts (n=27). Progression free survival and overall survival were determined by Cox regression. Results: All pts had prior nephrectomy and clear cell histology. The groups were matched by age (median 61), gender (male 74%), Heng risk (favorable 37%, intermediate 59%, poor 4%), sunitinib induced hypertension (67%), sunitinib dose reduction/treatment interruption (41%), smoking status (active 7%), use of angiotensin system inhibitors (41%), the presence of more than one metastases site (96%), and pre-tx neutrophil to lymphocyte ratio (> 3 in 22%). Furthermore, they were balanced regarding the presence of lung (68%), liver (31%), and bone (43%) metastases, and the use of bisphosphonates (32%). In prior HDIL2 versus tx naïve pts, objective response was partial response/stable disease 89% (n=24) versus 74% (n=20), and progressive disease at first imaging evaluation within the first 3 months (mos) 11% (n=3) versus 26% (n=7) (p=0.29, OR 2.4). Median progression free survival was 21 versus 12 mos (HR 2.3, p=0.005), and median overall survival 25 versus 20 mos (HR 2.2, p=0.013). Conclusions: In metastatic renal cell carcinoma patients treated with sunitinib, prior high dose IL-2 therapy may improve the outcome.