WT1 and leukemia: Moreover, the induced WT1‐specific T cells were probably involved in mediating graft‐versus‐leukaemia effects.2, 3, 4 Vaccination strategies, which inevitably rely on mobilization of the pre‐existing WT1‐specific T‐cell pool, likewise showed promising results in several clinical studies with response rates up to 63% in haematological diseases (reviewed in ref. 36).