Figure 6.

Repeated treatment with MEDI-565 and T cells does not abolish tumour cell susceptibility to MEDI-565/T-ell-mediated apoptosis. AsPC-1 tumour cells (6 × 10⁶) were cultured with T cells (3 × 10⁷) in 150 cm² T flasks with MEDI-565 or Cont BiTE (100 ng ml⁻¹). Additional BiTE molecules were added every 3 days, and after 10-day incubation, floating cells were washed out and cells were allowed to expand for 7 days (one cycle). Three cycles of attack/rest were repeated for each condition over 50 days. Adherent AsPC-1 cells were harvested and used as target cells for cytotoxicity assay. After 5 days of incubation with T cells, tumour cells were stained as described in the Figure 4 legend. Annexin V-positive cells in lineage marker-negative, CEA+ tumour cells were evaluated. The cytotoxicity value of the incubation with AsPC-1 target cells from long-term culture without BiTE molecule was set as 100%, and each cytotoxicity value is shown as a percentage relative to this condition. The assay was repeated twice with similar results.