Limits...
Rapid sequential gain of ABL1 kinase domain mutations with a complex karyotype in the progression of chronic myelogenous leukemia.

Chung Y, Eom HS, Lee H, Park S, Shim H, Cho EH, Kong SY - Ann Lab Med (2014)

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

CML is a myeloproliferative disease characterized by the Philadelphia (Ph) chromosome, in which the oncogenic BCR-ABL1 fusion gene encodes a constitutively active tyrosine kinase... First-line treatment using the BCR-ABL tyrosine kinase inhibitor (TKI) imatinib has significantly changed the disease course of CML... Resistance to imatinib may be overcome by treatment with second-line TKIs, including dasatinib, nilotinib, and bosutinib, which are active against most mutations; however, some mutations bring about resistance to these second-line drugs as well... We describe a CML patient who rapidly progressed to blast crisis following the sequential acquisition of ABL1 KD mutations with a complex karyotype... Conventional karyotyping showed complex numerical and structural abnormalities: 44~46,XX,-8,-9,t(9;22)(q34;q11.2),-15,-17,-18,+2~3mar[cp15]... FISH showed BCR-ABL1 translocation of 96%, with 14% showing a three-fusion signal of amplification, a finding known to be associated with imatinib resistance... Conventional cytogenetic analysis showed clonal evolution: 44,XX,der(8;15)(q10;q10),der(9)del(9)(p22)add(9)(q34),t(9;22)(q34;q11.2),-20[20]... FISH results showed BCR-ABL1 translocation of 66%; however, amplification of the fusion signal was not observed... We describe here the case of a CML patient who rapidly developed imatinib resistance within two months and dasatinib resistance within two weeks, each instance accompanied by a corresponding ABL1 KD mutation... We performed mutational screening by direct sequencing, the method currently recommended for ABL1 KD mutation analysis... However, this method cannot detect subclones present in less than 10-20% of the BCR-ABL1 cell pool... Thus, subclones harboring mutations may have been present but could not be detected, possibly having undergone clonal expansion after the depletion of subclones sensitive to TKIs... However, a more sensitive method of genomic analysis may reveal the presence of these low-level mutations and provide critical information for selecting subsequent therapy and predicting responses.

Show MeSH
The mutational analysis of ABL1 kinase domain with conventional direct sequencing at the time of diagnosis (top row), after development of imatinib resistance (middle row), and after development of dasatinib resistance (bottom row). (A) E255K (c.763G>A) was detected after development of imatinib resistance. (B) T315I (c.944C>T) was first detected after switchover to dasatinib resistance.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4151012&req=5

Figure 1: The mutational analysis of ABL1 kinase domain with conventional direct sequencing at the time of diagnosis (top row), after development of imatinib resistance (middle row), and after development of dasatinib resistance (bottom row). (A) E255K (c.763G>A) was detected after development of imatinib resistance. (B) T315I (c.944C>T) was first detected after switchover to dasatinib resistance.

Mentions: On day 53 of treatment, the patient visited the emergency room with fever and myalgia. Her white blood cell (WBC) count had increased to 256×109/L with 89% blasts. Flow cytometric analysis showed that 98.3% of the blasts were positive for CD34, 84.0% for terminal deoxynucleotidyl transferase (TdT), 99.4% for CD19, 47.3% for CD20, 99.7% for HLA-DR, and 49.5% for CD33. They were negative for CD10 and other T-cell and myeloid lineage markers; these findings were consistent with those for B lymphoid blasts. Imatinib was discontinued and replaced with dasatinib (140 mg/day). A BM examination three days later showed a hypocellular marrow with an increased number of blasts. Conventional karyotyping showed complex numerical and structural abnormalities: 44~46,XX,-8,-9,t(9;22)(q34;q11.2),-15,-17,-18,+2~3mar[cp15]. FISH showed BCR-ABL1 translocation of 96%, with 14% showing a three-fusion signal of amplification, a finding known to be associated with imatinib resistance [3, 10]. The BCR-ABL1 transcript level increased to 11.454% IS. E255K, a dasatinib-sensitive mutant, was detected by direct sequencing (Fig. 1A) [6].


Rapid sequential gain of ABL1 kinase domain mutations with a complex karyotype in the progression of chronic myelogenous leukemia.

Chung Y, Eom HS, Lee H, Park S, Shim H, Cho EH, Kong SY - Ann Lab Med (2014)

The mutational analysis of ABL1 kinase domain with conventional direct sequencing at the time of diagnosis (top row), after development of imatinib resistance (middle row), and after development of dasatinib resistance (bottom row). (A) E255K (c.763G>A) was detected after development of imatinib resistance. (B) T315I (c.944C>T) was first detected after switchover to dasatinib resistance.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4151012&req=5

Figure 1: The mutational analysis of ABL1 kinase domain with conventional direct sequencing at the time of diagnosis (top row), after development of imatinib resistance (middle row), and after development of dasatinib resistance (bottom row). (A) E255K (c.763G>A) was detected after development of imatinib resistance. (B) T315I (c.944C>T) was first detected after switchover to dasatinib resistance.
Mentions: On day 53 of treatment, the patient visited the emergency room with fever and myalgia. Her white blood cell (WBC) count had increased to 256×109/L with 89% blasts. Flow cytometric analysis showed that 98.3% of the blasts were positive for CD34, 84.0% for terminal deoxynucleotidyl transferase (TdT), 99.4% for CD19, 47.3% for CD20, 99.7% for HLA-DR, and 49.5% for CD33. They were negative for CD10 and other T-cell and myeloid lineage markers; these findings were consistent with those for B lymphoid blasts. Imatinib was discontinued and replaced with dasatinib (140 mg/day). A BM examination three days later showed a hypocellular marrow with an increased number of blasts. Conventional karyotyping showed complex numerical and structural abnormalities: 44~46,XX,-8,-9,t(9;22)(q34;q11.2),-15,-17,-18,+2~3mar[cp15]. FISH showed BCR-ABL1 translocation of 96%, with 14% showing a three-fusion signal of amplification, a finding known to be associated with imatinib resistance [3, 10]. The BCR-ABL1 transcript level increased to 11.454% IS. E255K, a dasatinib-sensitive mutant, was detected by direct sequencing (Fig. 1A) [6].

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

CML is a myeloproliferative disease characterized by the Philadelphia (Ph) chromosome, in which the oncogenic BCR-ABL1 fusion gene encodes a constitutively active tyrosine kinase... First-line treatment using the BCR-ABL tyrosine kinase inhibitor (TKI) imatinib has significantly changed the disease course of CML... Resistance to imatinib may be overcome by treatment with second-line TKIs, including dasatinib, nilotinib, and bosutinib, which are active against most mutations; however, some mutations bring about resistance to these second-line drugs as well... We describe a CML patient who rapidly progressed to blast crisis following the sequential acquisition of ABL1 KD mutations with a complex karyotype... Conventional karyotyping showed complex numerical and structural abnormalities: 44~46,XX,-8,-9,t(9;22)(q34;q11.2),-15,-17,-18,+2~3mar[cp15]... FISH showed BCR-ABL1 translocation of 96%, with 14% showing a three-fusion signal of amplification, a finding known to be associated with imatinib resistance... Conventional cytogenetic analysis showed clonal evolution: 44,XX,der(8;15)(q10;q10),der(9)del(9)(p22)add(9)(q34),t(9;22)(q34;q11.2),-20[20]... FISH results showed BCR-ABL1 translocation of 66%; however, amplification of the fusion signal was not observed... We describe here the case of a CML patient who rapidly developed imatinib resistance within two months and dasatinib resistance within two weeks, each instance accompanied by a corresponding ABL1 KD mutation... We performed mutational screening by direct sequencing, the method currently recommended for ABL1 KD mutation analysis... However, this method cannot detect subclones present in less than 10-20% of the BCR-ABL1 cell pool... Thus, subclones harboring mutations may have been present but could not be detected, possibly having undergone clonal expansion after the depletion of subclones sensitive to TKIs... However, a more sensitive method of genomic analysis may reveal the presence of these low-level mutations and provide critical information for selecting subsequent therapy and predicting responses.

Show MeSH