Mély remisszióban lévő CML-es beteg hirtelen kezdetű pancytopeniája

Összefoglaló. A mély molekuláris remisszióban lévő CML-es betegnél láz, izomfájdalmak alakultak ki, melyet jelentős kétvonalas cytopenia kísért. Alapbetegségének blasztos transzfomációja mellett, az utazási anamnézisre tekintettel a differenciáldiagnosztika trópusi betegségekre is kiterjedt. Dengue-lázat diagnosztizáltunk, melyből a beteg szövődmény nélkül felépült. Summary. A CML patient in deep molecular remission was admitted with fever, muscle pain, followed by pronounced bilineage cytopenia. In addition to possible blastic transformation, tropical diseases were also included in the differential diagnosis, due to travel history. Dengue fever was diagnosed, and the patient recovered without any complications.

DNA Damage and DNA Damage Response in Chronic Myeloid Leukemia

DNA damage and alterations in the DNA damage response (DDR) are critical sources of genetic instability that might be involved in BCR-ABL1 kinase-mediated blastic transformation of chronic myeloid leukemia (CML). Here, increased DNA damage is detected by γH2AX foci analysis in peripheral blood mononuclear cells (PBMCs) of de novo untreated chronic phase (CP)-CML patients (n = 5; 2.5 γH2AX foci per PBMC ± 0.5) and blast phase (BP)-CML patients (n = 3; 4.4 γH2AX foci per PBMC ± 0.7) as well as CP-CML patients with loss of major molecular response (MMR) (n = 5; 1.8 γH2AX foci per PBMC ± 0.4) when compared to DNA damage in PBMC of healthy donors (n = 8; 1.0 γH2AX foci per PBMC ± 0.1) and CP-CML patients in deep molecular response or MMR (n = 26; 1.0 γH2AX foci per PBMC ± 0.1). Progressive activation of erroneous non-homologous end joining (NHEJ) repair mechanisms during blastic transformation in CML is indicated by abundant co-localization of γH2AX/53BP1 foci, while a decline of the DDR is suggested by defective expression of (p-)ATM and (p-)CHK2. In summary, our data provide evidence for the accumulation of DNA damage in the course of CML and suggest ongoing DNA damage, erroneous NHEJ repair mechanisms, and alterations in the DDR as critical mediators of blastic transformation in CML.

Accumulation of DNA Damage and Alteration of the DNA Damage Response in Chronic Myeloid Leukemia

The accumulation of DNA damage and the alteration of the DNA damage response (DDR) are critical features of genetic instability that is presumed to be implicated in BCR/ABL1-mediated blastic transformation of chronic myeloid leukemia (CML). The aim of our study was to analyze underlying mechanisms of genetic instability with regard to DNA damage such as DNA double-strand breaks (DSB), DSB repair and DDR signaling during blastic transformation of CML. Immunofluorescence microscopy of γH2AX was performed for quantification of DSB in peripheral blood mononuclear cells (PBMC) of 8 healthy individuals, 24 chronic phase (CP)-CML patients under current/discontinued tyrosine kinase inhibitor (TKI) treatment (21 patients in deep molecular response (DMR), 3 patients in major molecular response (MMR)), 5 CP-CML patients under current/discontinued TKI treatment with loss of MMR, 3 de novo non-treated CP-CML patients and 2 blast phase (BP)-CML patients. In addition, immunofluorescence microscopy of γH2AX/53BP1 was used for semi-quantification of error-prone DSB repair. Furthermore, immunoblotting of p-ATM, p-ATR, p-CHK1, p-CHK2 and p-TP53 was performed in PBMC of CML patients in comparison to PBMC of healthy individuals. Our analysis revealed an increase in numbers of γH2AX foci in PBMC of CP-CML patients under current/discontinued TKI treatment with loss of MMR (1.8 γH2AX foci per PBMC ± 0.4), in PBMC of de novo non-treated CP-CML patients (2.3 γH2AX foci per PBMC ± 0.7) and in PBMC of BP-CML patients (4.9 γH2AX foci per PBMC ± 0.9) as compared to the number of γH2AX foci in PBMC of healthy individuals (1.0 γH2AX foci per PBMC ± 0.1) and in PBMC of CP-CML patients under current/discontinued TKI treatment in DMR/MMR (1.0 γH2AX foci per PBMC ± 0.1) (Figure 1A and B). Analysis of co-localizing γH2AX/53BP1 foci in PBMC suggested progressive activation of error-prone nonhomologous end-joining repair mechanisms during blastic transformation in CML. Signatures of p-ATM, p-ATR, p-CHK1, p-CHK2 and p-TP53 indicated alterations of the DDR. In summary, our data provide evidence for an accumulation of DNA damage in PBMC of CML patients towards BP-CML patients. We hypothesize that ongoing DSB generation, error-prone DSB repair and DDR alterations might be critical mechanisms of blastic transformation in CML. Figure 1 Analysis of γH2AX foci in freshly isolated peripheral blood mononuclear cells (PBMC) of healthy individuals and chronic myeloid leukemia (CML) patients. (A) Exemplary immunofluorescence microscopic images of γH2AX foci (green, Alexa 488) and cell nuclei (blue, DAPI) in PBMC of a healthy individual (HEALTHY#3), a chronic phase CML patient with a deep molecular response to tyrosine kinase inhibitor (CP-CML DMR#16), a de novo non-treated chronic phase CML patient (CP-CML#1) and a blast phase CML patient (BP-CML#2). (B) γH2AX foci levels in PBMC of healthy individuals and in PBMC of CML patients. Figure 1 Disclosures Saussele: Pfizer: Honoraria; Novartis: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Fabarius:Novartis: Research Funding.