E2A HLF FUSION CDNAS AND THE USE OF RT-PCR FOR THE DETECTION OF MINIMAL RESIDUAL DISEASE IN T(1719)(Q22P13) ACUTE LYMPHOBLASTIC-LEUKEMIA/

Three cases of acute lymphoblastic leukemia (ALL) with the rare t(17;1 9)(q22;p13) translocation were investigated for E2A/HLFfusion genes us ing reverse transcription coupled with polymerase chain reaction (RT-P CR). The patients had C-ALL, F/17 years (case 1) or pre-B ALL, M/11 ye ars (case 2) and M/13 years (case 3). Case 1 had an event-free surviva l (EFS) of 42 months. Case 2 was ultimately refractory to treatment. C ase 3 presented following EFS of 16 months in morphological remission (1% blasts), but with immunological and cytogenetic evidence of active disease, then relapsed, remitted and relapsed. Type II E2A/HLFfusion cDNA was found at diagnosis (cases 1, 2), at presentation (case 3) and in all samples tested, whether with active disease or in complete rem ission (CR). Case 3 showed, in addition, type I fusion E2A/HLF cDNA at presentation, through induction therapy when there was evidence of ac tive disease, but not in CR. Cases 1 and 3 had bone marrow transplanta tion while in CR but with residual disease detectable by RT-PCR. All p atients have died of ALL. Two cases (2 and 3) had hypercalcemia with b one lesions. No case had any evidence of disseminated intravascular co agulation. This is the first demonstration of the value of RT-PCR for the detection of minimal residual disease in t(17;19) ALL.