Outcome of rapid disease progression in the treatment break following cytoreductive nephrectomy (CN) after presurgical sunitinib in patients with primary metastatic renal cell carcinoma (RCC).

Abstract

4611 Background: There is concern that interruption of tyrosine kinase inhibitors (TKI) triggers disease progression (PD) and metastasis. This is based on preclinical models and observation of rapid PD in the postsurgical treatment break in patients pretreated with TKI. Little is known about the frequency of PD during postsurgical TKI interruption and its outcome. These data may have implications for neoadjuvant or presurgical treatment concepts. Methods: Of 66 patients from two closed phase II trials investigating 2-3 months presurgical sunitinib for primary metastatic clear-cell RCC, 45 were evaluated in this retrospective analysis because they had absence of PD prior to planned surgery and underwent CN (35 [78%] MSKCC intermediate and 10 [22%] poor risk). Patients had CT scans at the end of pretreatment and at 4 weeks post-nephrectomy before restarting sunitinib. In patients with postsurgical RECIST PD at 4 weeks when compared to the preoperative CT scan overall survival (OS) was measured from the time of nephrectomy and compared to patients without treatment break PD. Results: Median OS of 45 patients from the time of surgery was 22 months (13.0-31.5 months). Overall 14 patients progressed during treatment break (31%), with new sites of disease in 5/14 (35%). Reintroduction of sunitinib resulted in disease stabilisation or better in 13. Patients with poor risk were represented in the progressors (n=4[28%]) and non-progressors (n=6 [19%]) (p=0.7 fishers exact test). The hazard ratio (HR) for death associated with PD during treatment break was 1.90 (95% CI 0.89-4.08). OS for non-progressors was 25 months (15-NA) and 13 months (6-27) for progressors. Conclusions: A significant proportion of patients develop PD upon sunitinib withdrawal in a 4 week recovery period following CN. In view of the small sample size these data suggest a strong trend toward treatment break PD being associated with a poor outcome. It is not clear whether this PD is related to interruption of TKI, surgery or a combination of factors. The EORTC SURTIME trial investigates treatment break PD after immediate CN and CN after sunitinib and may answer this question.