Reciprocal relationship between a Ph-negative clone with trisomy 8 associated with severe myelodysplasia and a Ph-positive clone following imatinib treatment in a patient with accelerated-phase chronic myelogenous leukemia (CML)

Clonal chromosomal aberrations in Philadelphia negative cells such as monosomy 7 and trisomy 8 may persist for years with no impact on the long term outcome in patients with chronic myeloid leukemia

The appearance of clonal chromosomal aberrations in Philadelphia negative cells (CCA/Ph-) during the treatment of chronic myeloid leukemia (CML) was recently confirmed. Importance of these findings has not been clearly defined. We present data on the time of appearance, persistence, size of the CCA/Ph- clone in terms of drugs used and hematological, cytogenetic and molecular response rates. The focus was on the peripheral blood cytopenias and myelodysplastic changes in the bone marrow microscopic evaluation. In 5 out of 155 (3,2%) CML patients, the persistent presence (up to nine years) of CCA/Ph- was found (monosomy 7 and trisomy 8 in unrelated clones in two patients treated with tyrosine kinase inhibitors; trisomy 8 in two patients on imatinib; trisomy 21 in one patient on interferon alfa treatment). Aberrations were present in median 24% Ph- cells in 3-15 subsequent analyses at different cytogenetic and molecular response time points. No evident myelodysplastic changes nor transformation to MDS/AML occurred in patients with CCA/Ph-. All the patients achieved major molecular response (MMR). It seems that CCA/Ph- presence does not affect the long term outcome in patients with chronic myeloid leukemia. Further complex monitoring of the CML patients with CCA/Ph- is still needed.

Carcinogenesis: alterations in reciprocal interactions of normal functional structure of biologic systems

The evolution of biologic systems (BS) includes functional mechanisms that in some conditions may lead to the development of cancer. Using mathematical group theory and matrix analysis, previously, it was shown that normally functioning BS are steady functional structures regulated by three basis regulatory components: reciprocal links (RL), negative feedback (NFB) and positive feedback (PFB). Together, they form an integrative unit maintaining system’s autonomy and functional stability. It is proposed that phylogenetic development of different species is implemented by the splitting of “rudimentary” characters into two relatively independent functional parts that become encoded in chromosomes. The functional correlate of splitting mechanisms is RL. Inversion of phylogenetic mechanisms during ontogenetic development leads cell differentiation until cells reach mature states. Deterioration of reciprocal structure in the genome during ontogenesis gives rise of pathological conditions characterized by unsteadiness of the system. Uncontrollable cell proliferation and invasive cell growth are the leading features of the functional outcomes of malfunctioning systems. The regulatory element responsible for these changes is RL. In matrix language, pathological regulation is represented by matrices having positive values of diagonal elements (TrA > 0) and also positive values of matrix determinant (detA > 0). Regulatory structures of that kind can be obtained if the negative entry of the matrix corresponding to RL is replaced with the positive one. To describe not only normal but also pathological states of BS, a unit matrix should be added to the basis matrices representing RL, NFB and PFB. A mathematical structure corresponding to the set of these four basis functional patterns (matrices) is a split quaternion (coquaternion). The structure and specific role of basis elements comprising four-dimensional linear space of split quaternions help to understand what changes in mechanism of cell differentiation may lead to cancer development.

Monosomy 7 with severe myelodysplasia developing during imatinib treatment of Philadelphia-positive chronic myeloid leukemia: two cases with a different outcome

Chromosomal abnormalities in Ph-negative metaphases from patients with chronic myeloid leukemia (CML) treated with imatinib have been described in some cases. Trisomy 8 is the most frequent, but monosomy 7 has also been described. However, the association of these chromosomal alterations with myelodysplasia has been scarcely reported. We report the appearance of monosomy 7 in Ph-negative cells, associated with severe dysplasia, in two patients with CML treated with imatinib, with a different outcome: one with a transient evolution and the other evolving to acute myeloid leukemia.

Acute myeloid leukemia developing during imatinib mesylate therapy for chronic myeloid leukemia in the absence of new cytogenetic abnormalities

The BCR/ABL tyrosine kinase inhibitor imatinib mesylate produces a high rate of cytogenetic responses in patients with Philadelphia (Ph)-positive chronic myeloid leukemia (CML), but secondary clonal chromosome abnormalities may develop in Ph-negative cells, and acute myeloid leukemia (AML) has been reported in patients with secondary chromosome abnormalities. We report a patient who developed AML during imatinib treatment of Ph-positive CML despite a cytogenetic response and absence of secondary chromosome abnormalities. Thus, development of AML as a rare event in CML patients with cytogenetic responses to imatinib therapy does not depend on the development of secondary cytogenetic abnormalities.

Myelodysplastic syndromes and acute leukemia developing after imatinib mesylate therapy for chronic myeloid leukemia

During therapy with imatinib, some patients with chronic myeloid leukemia (CML) develop chromosomal abnormalities in Philadelphia chromosome (Ph)-negative cells. These abnormalities are frequently transient and their clinical consequence is unclear. Although some reports have suggested that the abnormalities might be associated with secondary myelodysplastic syndrome (MDS), the diagnosis has not always been established using standard criteria. We report 3 cases of patients treated with imatinib for CML who were subsequently found to have chromosomal abnormalities in Ph-negative cells. One of them developed acute myelogenous leukemia (AML) and the other 2 developed high-risk MDS that rapidly transformed to AML. These cases were identified in a total study group of 1701 patients. Although these occurrences are rare, the findings highlight the need for close monitoring of patients with CML treated with imatinib.