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:Several fusions have been tested clinically to show that antigenicity has not been a major problem, such as anti-TNFR fusions (42), DAB389IL-2 (43), and VEGFR fusion (VEGF-Trap in patients with solid tumors and non-Hodgkin's lymphomas; ref.
Category: