Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Sunitinib is one of several agents, including sorafenib, bevacizumab, and temsirolimus, which target the inhibition of pro-angiogenic growth factor activity and have shown favorable results in clinical trials against metastatic clear-cell RCC [15-17].
Category: