Patients treated with the highly reactive DMF5 or gp100(154), but not DMF4 TCR, had increased serum IFN-γ levels after treatment. Patient IFN-γ serum levels were measured daily before, during, and after cell infusion by ELISA. (A) Serum IFN-γ levels increased from baseline to a peak at 3 to 6 days after cell infusion (3 representative DMF5 patients are shown). (B) Peak IFN-γ levels in serum after treatment for patients treated with DMF5, gp100(154), and DMF4 TCR-transduced cells. Only patients treated with the highly reactive DMF5 or gp100(154) TCR demonstrated increased IFN-γ in serum (P = .001 and P < .001, respectively, compared with P = .09 for DMF4 TCR).