Wyatt, William A.

Abstract We investigated a new method using fluorescence in situ hybridization and DNA probes that span the common breakpoints of t(9;22)(q34;q11.2) and that detect double BCR/ABL fusion (D-FISH) in bone marrow cells with this translocation, one on the abnormal chromosome 9 and one on the Philadelphia chromosome (Ph chromosome). D-FISH patterns were abnormal in 30 of 30 specimens with classic, simple, complex, and masked Ph chromosomes. Based on 200 nuclei from each of 30 normal specimens, the mean percentage of false-positive cells was 0.25 ± 0.39. Thirty-seven specimens from 10 patients were studied before treatment and two or more times at 4-month intervals after treatment with interferon-α2b (IFN-α2b) with or without ara-C. Based on 200 nuclei, the results of D-FISH in these specimens correlated closely with quantitative cytogenetics and accurately quantified disease within a few percent. We studied 6,000 nuclei for each of six specimens, three normal and three from patients with chronic myeloid leukemia (CML) in cytogenetic remission. The normal cutoff for 6,000 nuclei was 0.079% and patients in cytogenetic remission had residual disease ranging from 7 (0.117%) to 53 (0.883%) Ph-positive nuclei. We conclude that D-FISH can detect the Ph chromosome and its variant translocations and accurately quantify disease in CML at diagnosis and at all times after treatment, including cytogenetic remission.

Abstract Using a highly sensitive fluorescence in situ hybridization method with probes for BCR and ABL1 (D-FISH), we studied 37 paired sets of bone marrow and blood specimens, collected within 24 to 96 hours of each other, from 10 patients before and during treatment for chronic myeloid leukemia (CML). The normal range for 500 interphase nuclei was ≤4 (≤0.8%) nuclei based on 10 bone marrow and 10 blood specimens from normal individuals. The percentage of neoplastic nuclei was usually lower in blood than bone marrow. However, changes in the percentage of neoplastic nuclei in blood and bone marrow tracked closely over the course of therapy and with the results of quantitative cytogenetic studies on bone marrow. This result indicates that D-FISH is useful to test blood from patients with CML to monitor therapy. Moreover, by analysis of 6,000 nuclei with D-FISH, residual disease was identified in bone marrow and blood for patients in complete cytogenetic remission. Consequently, D-FISH analyses of interphase nuclei from blood could substitute for Q-cytogenetic studies on bone marrow. Thus, it may not be necessary to collect bone marrow samples so frequently to monitor therapy in CML.

Using a highly sensitive fluorescence in situ hybridization method with probes for BCR and ABL1 (D-FISH), we studied 37 paired sets of bone marrow and blood specimens, collected within 24 to 96 hours of each other, from 10 patients before and during treatment for chronic myeloid leukemia (CML). The normal range for 500 interphase nuclei was ≤4 (≤0.8%) nuclei based on 10 bone marrow and 10 blood specimens from normal individuals. The percentage of neoplastic nuclei was usually lower in blood than bone marrow. However, changes in the percentage of neoplastic nuclei in blood and bone marrow tracked closely over the course of therapy and with the results of quantitative cytogenetic studies on bone marrow. This result indicates that D-FISH is useful to test blood from patients with CML to monitor therapy. Moreover, by analysis of 6,000 nuclei with D-FISH, residual disease was identified in bone marrow and blood for patients in complete cytogenetic remission. Consequently, D-FISH analyses of interphase nuclei from blood could substitute for Q-cytogenetic studies on bone marrow. Thus, it may not be necessary to collect bone marrow samples so frequently to monitor therapy in CML.

We investigated a new method using fluorescence in situ hybridization and DNA probes that span the common breakpoints of t(9;22)(q34;q11.2) and that detect double BCR/ABL fusion (D-FISH) in bone marrow cells with this translocation, one on the abnormal chromosome 9 and one on the Philadelphia chromosome (Ph chromosome). D-FISH patterns were abnormal in 30 of 30 specimens with classic, simple, complex, and masked Ph chromosomes. Based on 200 nuclei from each of 30 normal specimens, the mean percentage of false-positive cells was 0.25 ± 0.39. Thirty-seven specimens from 10 patients were studied before treatment and two or more times at 4-month intervals after treatment with interferon-α2b (IFN-α2b) with or without ara-C. Based on 200 nuclei, the results of D-FISH in these specimens correlated closely with quantitative cytogenetics and accurately quantified disease within a few percent. We studied 6,000 nuclei for each of six specimens, three normal and three from patients with chronic myeloid leukemia (CML) in cytogenetic remission. The normal cutoff for 6,000 nuclei was 0.079% and patients in cytogenetic remission had residual disease ranging from 7 (0.117%) to 53 (0.883%) Ph-positive nuclei. We conclude that D-FISH can detect the Ph chromosome and its variant translocations and accurately quantify disease in CML at diagnosis and at all times after treatment, including cytogenetic remission.