BACKGROUND: From 10% to 26% of patients with metastatic renal cell carcinoma 
(mRCC) experience rapidly progressive disease (PD) on treatment with sunitinib.
OBJECTIVE: To investigate the benefit of subsequent treatment with another 
tyrosine kinase inhibitor (TKI) or a mammalian target of rapamycin (mTOR) 
inhibitor in such primary refractory patients.
DESIGN, SETTING, AND PARTICIPANTS: A total of 150 mRCC patients with rapidly PD 
on first-line sunitinib (within two cycles, n=93, or four cycles, n=57) were 
identified: median age 59yr; nephrectomy 86%; histological subtypes: clear cell 
(77.8%), papillary (14%), and sarcomatoid features (18%); according to the 
Memorial Sloan-Kettering Cancer Center and French classifications: good risk 
(11% and 7%, respectively), intermediate (68% and 63%, respectively), and poor 
(21% and 29%, respectively).
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Data were retrospectively 
collected by a questionnaire from 19 European oncology centers between March 
2005 and March 2011. Progression-free survival (PFS) and overall survival (OS) 
were calculated (Kaplan-Meier method).
RESULTS AND LIMITATIONS: Median OS from the start of first-line treatment was 
7.4mo. Second-line treatment was administered to 86 (57%) patients (44 mTOR 
inhibitors: 23 everolimus and 21 temsirolimus; 39 TKIs alone or in combination; 
three chemotherapy). Second-line PFS was not significantly different between 
TKIs and mTOR inhibitors (2.0 vs 0.9mo; p=0.536). Median OS from the start of 
second-line treatment was 5.0mo for mTOR inhibitors and 6.6mo for TKIs (p=0.15).
CONCLUSIONS: Treatment with further TKIs or mTOR inhibitors for mRCC patients 
primarily refractory to first-line sunitinib in the observed time period 
achieved very minimal benefit, suggesting avoiding TKI rechallenge and possibly 
preferring alternative strategies, such as immune checkpoint inhibitors, after 
PD to a treatment line including a TKI in this setting.
PATIENT SUMMARY: The present work collected data about 150 patients affected by 
metastatic renal cell carcinoma, who received one of the current standard of 
care as first-line treatment, namely, the antiangiogenic drug sunitinib, and 
experienced rapid worsening of the disease. We investigated and described the 
subsequent outcome of such patients treated with two different types of drug, 
administered as second-line therapy, to better understand the best strategy to 
adopt for patients who got no benefit from sunitinib and to describe the current 
therapeutic approach in such cases.