Tetraploidy acute myeloid leukaemia after chromosome 16 inversion

The prognostic implications of tetraploidy/near-Tetraploidy in acute myeloid leukemia: a case series and systematic review of the literature

The prognostic significance and optimal management of tetraploidy/near-tetraploidy acute myeloid leukemia (T/NT AML) remains unclear given its limited data. This is especially true after factoring in additional chromosomal alterations, which carry their own prognostic weight. Here, we analyze 128 cases of T/NT in AML from the literature along with two additional cases, which is the largest review of this subject to date. Based on our retrospective analysis, we found that regardless of the risk status attributed to cytogenetics, the prognosis of tetraploid or near-tetraploid AML is dismal and should be incorporated within the unfavorable risk group. Complete remission is paramount to survival in this population. Specific induction protocols for high-risk AML appear to have higher rates of complete remission in the T/NT AML population. Moreover, longer overall survival can be achieved with chemotherapy followed by allogeneic stem cell transplantation at first complete remission.

Telomere Shortening in Hematological Malignancies with Tetraploidization-A Mechanism for Chromosomal Instability?

Aneuploidy, the presence of an abnormal number of chromosomes in a cell, is one of the most obvious differences between normal and cancer cells. There is, however, debate on how aneuploid cells arise and whether or not they are a cause or a consequence of tumorigenesis. Further, it is important to distinguish aneuploidy (the “state” of the karyotype) from chromosomal instability (CIN; the “rate” of karyotypic change). Although CIN leads to aneuploidy, not all aneuploid cells exhibit CIN. One proposed route to aneuploid cells is through an unstable tetraploid intermediate because tetraploidy promotes chromosomal aberrations and tumorigenesis. Tetraploidy or near-tetraploidy (T/NT) (81–103 chromosomes) karyotypes with or without additional structural abnormalities have been reported in acute leukemia, T-cell and B-cell lymphomas, and solid tumors. In solid tumors it has been shown that tetraploidization can occur in response to loss of telomere protection in the early stages of tumorigenesis in colon cancer, Barrett’s esophagus, and breast and cervical cancers. In hematological malignancies T/NT karyotypes are rare and the role of telomere dysfunction for the induction of tetraploidization is less well characterized. To further our understanding of possible telomere dysfunction as a mechanism for tetrapolydization in hematological cancers we here characterized the chromosomal complement and measured the telomere content by interphase nuclei quantitative fluorescence in situ hybridization (iQFISH) in seven hematological cancer patients with T/NT karyotypes, and after cytogenetic remission. The patients were identified after a search in our local cytogenetic registry in the 5-year period between June 2012 and May 2017 among more than 12,000 analyzed adult patients in this period. One advantage of measuring telomere content by iQFISH is that it is a single-cell analysis so that the telomere content can be distinguished between normal karyotype cells and cells with T/NT karyotypes. We find that the telomeres are particularly short in cells with T/NT karyotypes as compared with normal cells, and in T/NT karyotypes harboring additional chromosomal aberrations as well. These findings suggest that telomere dysfunction in hematological malignancies may be a mechanism for tetraploidization and CIN.