Appearance of acute leukemia-associated P190^{BCR ABL} in chronic myelogenous leukemia may correlate with disease progression

The Philadelphia translocation in chronic myelogenous leukemia (CML) results in the production of a 210 kD BCR-ABL protein. In contrast, in 50% of Philadelphia-positive acute leukemias, the translocation results in the production of a 190 kD BCR-ABL protein. To investigate the hypothesis that the production of P190 may be associated with the progression from chronic phase to blast crisis in CML, we used polymerase chain reaction to analyze blood from 37 patients with accelerated phase/blast crisis CML for the transcripts coding for the P210^BCR-ABL and P190^BCR-ABL. The mRNA encoding for P210 was detected in all patients. In three patients, mRNA encoding both P210 and P190 was present. In two of these three patients, samples were available from the time of initial diagnosis. Analysis of these samples did not reveal any transcripts for P190. We conclude that in some patients the appearance of P190^BCR-ABL may correlate with transformation to a more aggressive, terminal phase of CML.