INTERFERON RESPONSE IN CHRONIC MYELOID-LEUKEMIA CORRELATES WITH AEL BCR EXPRESSION - A PRELIMINARY-STUDY/

alpha-Interferon (EFN) has been used to induce cytogenetic remission i n chronic myeloid leukaemia (CML), but there are few indicators to pre dict IFN response. The role of the chimaeric BCR/ABL gene in the malig nant process is undisputed. There are, however, conflicting views as t o whether the breakpoint site within the BCR gene, and the type of mRN A produced determine disease prognosis and progression. The function a nd clinical significance of the newly discovered ABL/BCR mRNA has not been investigated for a correlation with CML prognosis or response to therapy. We have used a two-step reverse transcriptase polymerase chai n reaction (RT-PCR) to detect the transcripts of the chimaeric genes B CR/ABL, ABL/BCR, as well as the normal ABL and BCR genes in 24 CML pat ients treated with IFN. Because of the variable expression of the four transcripts at presentation, a correlation between gene expression, p rognosis and clinical progression was examined. No correlation between prognosis and gene expression was seen, Also, no correlation was foun d between expression of BCR, ABL or BCR/ABL mRNA and response to treat ment with IFN. However, 7/10 ABL/BCR mRNA positive patients achieved a major cytogenetic response to IFN; but of the 13 ABL/BCR mRNA negativ e patients, only two achieved a major cytogenetic response (P=0.013). Further studies are required to confirm these findings.