A18: GKT-AML5, WT1 and SSX2IP are frequently expressed in adult B-cell acute lymphocytic leukaemia
1University of Bedfordshire, Luton,Bedfordshire, UK,2Southampton University Hospital, Southampton, UK,3Southampton University Hospital, Southampton, UK,4University of Bedfordshire, Luton,Bedfordshire, UK
Acute lymphoblastic leukaemia (ALL) is a form of leukaemia characterized by excess lymphoblasts. If untreated the disease progresses rapidly and can be fatal within weeks to months. Adult patients with ALL who have an allogeneic stem cell transplant (allo-SCT) have an improved overall survival rate of 27-65% compared with 15-45% in patients receiving chemotherapy only (1-3).The benefits of allogeneic transplantation may in part be due to a graft-versus-leukaemia response however in ALL few diseases related target antigens have been described. The identification of ALL-associated antigens' has the potential to identify new targets for immunotherapy during first remission when tumour loads are low, or post-transplant when healthy donor T cells persist and the occurrence of graft versus leukaemia responses can crucially improve outcome.
Using RT-PCR we have analysed the expression of 23 known tumour antigens, including the five identified by antibody specific-profiling (Bonney et al, in preparation). We examined their expression in leukaemia cell lines, presentation adult B-ALL patient samples and healthy volunteer peripheral blood mononuclear cell samples. All PCR products were sequenced to confirm their specificity, and that all PCRs were repeated at least three times.
We found that the novel antigen, GKT-AML5, identified through the immunoscreening of an AML cDNA library with autologous sera (4), WT1 and SSX2IP are the most frequently expressed in patient samples but not found in healthy donor peripheral blood samples.
Further analysis of ALL patient samples and healthy donor leucocytes will indicate whether these antigens remain the most frequently expressed in adult B-ALL samples at disease diagnosis.