GOOD CORRELATION BETWEEN RT-PCR ANALYSIS AND RELAPSE IN PHILADELPHIA (PH1)-POSITIVE ACUTE LYMPHOBLASTIC-LEUKEMIA (ALL)

We sequentially performed cytogenetic analysis and RT-PCR analysis of BCR-ABL transcripts in 17 cases of Phl-positive ALL who had achieved h ematological complete remission (CR) with intensive chemotherapy (CT), Sixteen cases were studied prospectively. All but one of the patients had reached cytogenetic CR, but cytogenetic has low sensitivity in pr edicting relapse, Twelve patients relapsed, three died in first CR and two were alive In first CR, Two of five, two of four, and five of nin e patients who were allografted (in first or second CR), autografted a nd received consolidation CT, respectively, achieved negative two-roun d PCR in the bone marrow (BM): three died in CR, three remained in CR with negative two-step PCR in the BM and three relapsed after 22 to 28 months. In all cases, relapse was preceded by switch to PCR positivit y in the BM by 4 to 6 months, The remaining nine patients remained PCR -positive In the BM and relapsed after 2 to 16 months, In the four aut ografted cases, PCR was positive at the time of bone marrow harvest, T he two patients who received a purged transplant achieved negative PCR and prolonged CR, whereas the two patients who received an unpurged t ransplant remained PCR positive and relapsed, In 34% of the samples wh ere analysis was concomitant, sensitivity of PCR proved lower in the b lood than in the BM, These findings show that RT-PCR is a useful tool in the monitoring of MRD in Ph1 positive ALL.