Long-term response to sunitinib therapy for metastatic renal cell carcinoma

Sunitinib achieves objective response and prolongs progression-free survival (PFS) in patients with metastatic renal cell carcinoma (RCC). A subset of patients achieves long-term responses. The characteristics of patients who achieved long-term response (defined as patients achieving ongoing complete response [CR] or remaining progression free for > 18 months while receiving sunitinib) are reported.

A database of 186 patients treated with sunitinib alone (n = 89) or in combination (n = 97) in 9 clinical trials was reviewed; all had 1 year or more follow-up from sunitinib start to data cutoff for analysis. Median PFS was 10.8 months (95% CI, 8.3-13.3); median overall survival (OS) was 30.4 months (95% CI, 21.5-36.8 months) for the 186 patients. Thirty-four patients were identified as long-term responders because they either had durable CR or remained progression free while receiving sunitinib for > 18 months.

Best response for 34 long-term responders was CR in 3 patients, partial response (PR) in 24 patients, and stable disease in 7 patients. The median duration of sunitinib therapy was 24.9 months (range, 18.1-73.9 months). The median PFS among the long-term responders was 17.4 months (95% CI, 7-29.9 months) at a landmark PFS analysis performed after 18 months from treatment start. Univariate analysis from the 186 patients identified bone metastasis, lung metastasis, and intermediate/poor risk groups as adverse prognostic factors for long-term response.

Sunitinib achieves long-term response in a subset of patients with metastatic RCC. Lack of bone metastasis or lung metastasis and good MSKCC risk status may predict long-term response.