Emergence of clonal chromosomal abnormalities in Philadelphia negative hematopoiesis in chronic myeloid leukemia patients treated with nilotinib after failure of imatinib therapy

Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph) which results from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase CML.

Poor prognosis of chromosome 7 clonal aberrations in Philadelphia-negative metaphases and relevance of potential underlying myelodysplastic features in chronic myeloid leukemia

Clonal chromosome abnormalities in Philadelphia-negative cells could concern chronic myeloid leukemia patients treated by tyrosine kinase inhibitors. The European LeukemiaNet distinguishes -7/del(7q) abnormalities as a “warning”. However, the impact of clonal chromosome abnormalities, and specifically those of -7/del(7q), in Philadelphia-negative cells on clinical outcomes is unclear and based on case-reports showing morphological dysplasia and increased risk of acute myeloid leukemia, suggesting the coexistence of chronic myeloid leukemia and high-risk myelodysplastic syndrome. The aim of this study was to determine whether the impact of -7/del(7q) clonal chromosome abnormalities in Philadelphia-negative cells on the clinical outcome is different from that of other types of abnormalities, and we argue for an underlying associated high-risk myelodysplastic syndrome. Among 102 chronic myeloid leukemia patients with clonal chromosome abnormalities in Philadelphia-negative cells with more than a median of 6 years of follow up, patients with -7/del(7q) more frequently had signs of dysplasia, a lower cumulative incidence of deep molecular response and often needed further treatment lines, with the consequent impact on event-free and progression-free survival. Morphological features of dysplasia are associated with myelodysplastic syndrome/acute myeloid leukemia mutations and compromise the optimal response to tyrosine kinase inhibitors, irrespectively of the type of clonal chromosome abnormalities in Philadelphia-negative cells. However, mutation patterns determined by next-generation sequencing could not clearly explain the underlying high-risk disease. We hereby confirm the pejorative prognostic value of -7/del(7q) clonal chromosome abnormalities in Philadelphia-negative cells and suggest that myelodysplastic features constitute a warning signal that response to tyrosine kinase inhibitors may be less than optimal.

Clinical course of patients with incidental finding of 20q- in the bone marrow without a morphologic evidence of myeloid neoplasm

Deletion of the long arm of chromosome 20 (20q-) is a frequent finding in bone marrow karyotypes, mainly associated with myeloid neoplasms (MNs). Its clinical significance in the setting of normal bone marrow morphology is unclear. We described the clinical characteristics, cytogenetic findings, and outcome of 102 such patients seen at our institution from 2000-2014. Their median age was 66 years. The indication for bone marrow biopsy was either unexplained cytopenias (48%) or hematologic cancer staging/reevaluation (52%). In 88 (86%) patients, 20q- was an isolated finding. Thirty-nine (38%) patients previously received chemotherapy and 88 (86%) had cytopenias at the time of 20q- finding. After a median of 35 months, 12 (13%) patients developed MNs: 10 myelodysplastic syndromes, one acute myeloid leukemia and one myeloproliferative neoplasm. None of 14 patients with normal blood counts, but 7 of 35 (20%) with mild cytopenias, and 5 of 53 (9%) with moderate/severe cytopenias developed MNs. We did not find an association between the number of metaphases with 20q- and the development of MN. The incidental finding of 20q- in the bone marrow generally does not portend an early stage MN. Particularly, those without cytopenias at the time of diagnosis may have a good prognosis. Am. J. Hematol. 91:556-559, 2016. © 2016 Wiley Periodicals, Inc.

[Clinical observation of chromosomal abnormalities in Ph negative cells of chronic myeloid leukemia patients treated with tyrosine kinase inhibitors]

OBJECTIVE

To observe the clinical features, characteristics and outcomes of chromosomal abnormalities in Philadelphia negative cells (Ph(-)CA) of chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitor (TKI), and provide the evidence for clinical treatment.

METHODS

We collected and analyzed the clinical and laboratory data of 8 CML patients treated in the affiliated Tumor Hospital of Zhengzhou University from September 2011 to July 2015 and Ph(-)CA occurred after TKI therapy. Karyotypes and BCR-ABL fusion genes were analyzed by R-banding and real-time quantitative polymerase chain reaction (RT-PCR), respectively.

RESULTS

6 cases were male and 2 cases were female, with a median age of 51 (31-75) years old. 6 patients had low Sokal risk scores and 2 had intermediate scores. 4 cases of Ph(-) CA occurred with imatinib, 1 case with dasatinib and 3 cases with nilotinib. The median duration of Ph(-) CA appearance was 12.0 (1.7-34.5) months since taking TKI. Chromosomal abnormality +8 was the most common type in Ph(-)CA, which accounted for 50.0%, followed by -7 (25.0%). When found Ph(-)CA, all patients had complete hematologic response (CHR), but none got main molecular response (MMR). The Ph(-)CA had gone in 7 cases at the end of follow-up and the median duration was 6.2 (2.5-31.5) months. After Ph(-) CA disappeared, 1 patient obtained MMR and 2 cases achieved complete molecular response (CMR), but Ph(+) clone recurred in 1 case.

CONCLUSION

Ph(-)CA can be found in CML patients treated with imatinib, dasatinib and nilotinib, and +8 is the most common Ph(-)CA. So detection of karyotype is significant during treatment. Although most Ph(-)CA can disappear, -7/7q- or other complex karyotypes should be monitored closely.

Impact of additional chromosomal aberrations and BCR-ABL kinase domain mutations on the response to nilotinib in Philadelphia chromosome-positive chronic myeloid leukemia

BACKGROUND

Additional chromosomal aberrations in Philadelphia chromosome-positive chronic myeloid leukemia are non-random and strongly associated with disease progression, but their prognostic impact and effect on treatment response is not clear. Point mutations in the BCR-ABL kinase domain are probably the most common mechanisms of imatinib resistance.

DESIGN AND METHODS

We assessed the influence of additional chromosomal aberrations and BCR-ABL kinase domain mutations on the response to the second-generation tyrosine kinase inhibitor nilotinib after imatinib-failure. Standard cytogenetic analysis of metaphases was performed to detect additional chromosomal aberrations and the BCR-ABL kinase domain was sequenced to detect point mutations.

RESULTS

Among 53 patients with a median follow-up of 16 months, of whom 38, 5 and 10 were in chronic phase, accelerated phase and blast crisis, respectively, 19 (36%) had additional chromosomal aberrations and 20 (38%) had BCR-ABL kinase domain mutations. The 2-year overall survival rate of all patients with-out additional chromosomal aberrations (89%) was higher than that of patients with such aberrations (54%) (P=0.0025). Among patients with chronic phase disease, overall survival at 2 years was 100% and 62% for patients without or with additional chromosomal aberrations, respectively (P=0.0024). BCR-ABL kinase domain mutations were associated with lower remission rates in response to nilotinib, with 9 of 20 (45%) of these patients achieving a major cytogenetic remission as compared to 26 of 33 (79%) patients without mutations (P<0.05). However, overall survival was not affected by BCR-ABL kinase domain mutations.

CONCLUSIONS

Whereas BCR-ABL kinase domain mutations may confer more specific resistance to nilotinib, which will predominantly affect response rates, the presence of additional chromosomal aberrations may reflect genetic instability and, therefore, intrinsic aggressiveness of the disease which will be less amenable to subsequent alternative treatments and thus negatively affect overall survival. Conventional cytogenetic analyses remain mandatory during follow-up of patients with chronic myeloid leukemia under tyrosine kinase inhibitor therapy.