Cytogenetic response to alpha-interferon is predicted in early chronic phase XXXX by M-bcr breakpoint location.

@entity1 @entity1860 @entity1862
Alpha-interferon (alpha-IFN) therapy is an effective agent in early chronic phase (ECP) @entity1860 ( @entity1860 ), achieving hematologic control in the majority and major cytogenetic response (MCR) (reduction in Ph' +ve metaphases to < 35%) in a substantial minority. Currently no pretreatment markers exist to ascertain likelihood of meaningful response. The site of breakpoint in M-bcr and relationship to prognosis is controversial. Studies have been hampered by variation in definition of breakpoint and difference in treatment protocols. In this study of ECP @entity1860 @entity1 , Southern analysis and reverse transcription polymerase chain reaction (RT-PCR) were used to determine breakpoint location. @entity1 received alpha-IFN (9 x 10(6) units/day) and dose-adjusted @entity1862 (HU) to maintain granulocyte count between 1.0-2.0 x 10(9)/l for 6 months or more. Twelve of 31 @entity1 entered on the study achieved a MCR. The Sokal index did not predict for cytogenetic response to alpha-IFN. Eight of 11 @entity1 with 5' breakpoint achieved MCR compared to only four of 20 @entity1 with 3' breakpoint (P = 0.007). These results suggest site of M-bcr rearrangement may be predictive of response to alpha-IFN therapy. If verified by further study, this may allow more appropriate use of alpha-IFN with respect to other modalities such as allogeneic transplant.
