Pfp and IFN-γ were critical for the antitumor efficacy of T-scFv-CD28-ζ cells.

Subcutaneous growth of erbB2⁺ human COLO 205 cells in groups of 20 to 31 untreated and treated scid mice. Mice were injected intravenously with 2 doses (5 × 10⁶) of T cells from BALB/c, WT, pfp^−/−, IFN-γ^−/−, and pfp^−/−IFN-γ^−/− mice transduced with the scFv-anti-erbB2-ζ or scFv-anti-erbB2-CD28-ζ receptors on day 0 and day 1 after tumor inoculation. Mice were monitored for tumor growth for 100 days and results are recorded as the percentage of tumor-free mice in each group. The number of mice in each group is shown in parentheses. Tumor-free mice treated with T cells of the same strain were compared (T-scFv-CD28-ζ and T-scFv-ζ receptors) and statistically evaluated by Fisher exact test (*P ≤ .001, **P ≤ .0001).