WT1 and cancer: Yet, these responses could not be further expanded in vitro, again indicating an impairment of responses following WT1A vaccination.20 Given the weak responses elicited with WT1A vaccination, other groups have focussed on the modified WT1B epitope as an alternative strategy to induce anti-WT1 tumor responses in cancer patients.22, 23 However, there is still a lack of evidence to suggest that WT1B is superior to WT1A for use in anticancer vaccination trials.