Taru Kuittinen

Somatic STAT3 mutations in large granular lymphocytic leukemia.

BACKGROUND T-cell large granular lymphocytic leukemia is a rare lymphoproliferative disorder characterized by the expansion of clonal CD3+CD8+ cytotoxic T lymphocytes (CTLs) and often associated with autoimmune disorders and immune-mediated cytopenias. METHODS We used next-generation exome sequencing to identify somatic mutations in CTLs from an index patient with large granular lymphocytic leukemia. Targeted resequencing was performed in a well-characterized cohort of 76 patients with this disorder, characterized by clonal T-cell-receptor rearrangements and increased numbers of large granular lymphocytes. RESULTS Mutations in the signal transducer and activator of transcription 3 gene (STAT3) were found in 31 of 77 patients (40%) with large granular lymphocytic leukemia. Among these 31 patients, recurrent mutational hot spots included Y640F in 13 (17%), D661V in 7 (9%), D661Y in 7 (9%), and N647I in 3 (4%). All mutations were located in exon 21, encoding the Src homology 2 (SH2) domain, which mediates the dimerization and activation of STAT protein. The amino acid changes resulted in a more hydrophobic protein surface and were associated with phosphorylation of STAT3 and its localization in the nucleus. In vitro functional studies showed that the Y640F and D661V mutations increased the transcriptional activity of STAT3. In the affected patients, downstream target genes of the STAT3 pathway (IFNGR2, BCL2L1, and JAK2) were up-regulated. Patients with STAT3 mutations presented more often with neutropenia and rheumatoid arthritis than did patients without these mutations. CONCLUSIONS The SH2 dimerization and activation domain of STAT3 is frequently mutated in patients with large granular lymphocytic leukemia; these findings suggest that aberrant STAT3 signaling underlies the pathogenesis of this disease. (Funded by the Academy of Finland and others.).

Elevated procalcitonin predicts Gram-negative sepsis in haematological patients with febrile neutropenia

Abstract Objective: To compare semi-quantitative procalcitonin with C-reactive protein in predicting bacteraemia in haematological patients with neutropenic fever. Methods: A total of 77 patients treated with intensive chemotherapy for haematological malignancy at Kuopio University Hospital were candidates for study entry. Eleven of these patients did not fulfil the criteria for neutropenic fever, and 66 patients were finally included. Nineteen patients had acute myeloid leukaemia and 47 had received high-dose chemotherapy supported by autologous stem cell transplant. Ninety neutropenic fever episodes in these 66 patients fulfilled the study entry criteria, with microbiological cultures, procalcitonin and C-reactive protein measurements available. Serum procalcitonin and C-reactive protein were analyzed at the onset of each neutropenic fever episode on day 0, and then daily from days 1 to 4. Results: Bacteraemia was observed in 21 episodes (23%) and the criteria for severe sepsis were fulfilled in 13 episodes (14%). Half of the bacteraemic episodes were caused by Gram-negative bacteria. The kinetics of procalcitonin and C-reactive protein were similar, with increasing levels for 2 to 4 days after the onset of fever. The procalcitonin level on days 1, 2, 3 and 4 was associated with bacteraemia and Gram-negative bacteraemia, but not with the development of severe sepsis. On day 1, a procalcitonin level above 0.5 ng/ml had a sensitivity of 57% and 70% and specificity of 81% and 77% to predict bacteraemia and Gram-negative bacteraemia, respectively. Conclusions: An elevated level of procalcitonin within 24 h after the onset of neutropenic fever predicts bacteraemia and Gram-negative bacteraemia in haematological patients.

Efficacy of pre-emptively used plerixafor in patients mobilizing poorly after chemomobilization: a single centre experience

A significant proportion of patients with lymphoid malignancies are hard‐to‐mobilize with a combination of chemotherapy plus granulocyte colony‐stimulating factor (G‐CSF) (chemomobilization). Plerixafor is a novel drug used to improve mobilization of blood stem cells. However, it has been studied mainly in association with G‐CSF mobilization. We evaluated the efficacy of ‘pre‐emptive’ use of plerixafor after chemomobilization in patients who seem to mobilize poorly. During a 15 month period, altogether 63 patients with lymphoid malignancies were admitted to our department for blood stem cell collection. Sixteen patients (25%) received plerixafor after the first mobilization due to the low blood (B) CD34+ cell counts (n = 12) or poor yield of the first collection (n = 4). The median number of plerixafor injections was 1 (1–3). The median B‐CD34+ count after the first plerixafor dose was 39 × 106/L (<1–81) with the median increase of fivefold. Stem cell aphaereses were performed in 14/16 patients (88%) receiving plerixafor and a median of 2.9 × 106/kg (1.6–6.1) CD34+ cells were collected with a median of one aphaeresis (1–3). Altogether 13/16 patients mobilized with a combination of chemomobilization and plerixafor received high‐dose therapy with stem cell support and all engrafted. Pre‐emptive use of plerixafor after chemomobilization is efficient and safe and should be considered in poor mobilizers to avoid collection failure. In patients with low but rising B‐CD34+ counts, the use of plerixafor might be delayed as late mobilization may occur. Further studies are needed to optimize patient selection and timing of plerixafor.

Blood graft composition after plerixafor injection in patients with NHL

Plerixafor is used to mobilize CD34+ hematopoietic stem cells from bone marrow to circulation. Limited data are available in regard to graft cellular content collected after plerixafor.

Blood graft lymphocyte subsets after plerixafor injection in non-Hodgkin's lymphoma patients mobilizing poorly with chemotherapy plus granulocyte–colony-stimulating factor

BACKGROUND: A combination of chemotherapy plus granulocyte–colony‐stimulating factor (G‐CSF) (chemomobilization) is commonly used to mobilize CD34+ cells to circulation. Plerixafor, a chemokine CXCR4 antagonist, increases the mobilization of CD34+ cells and may also have effect on graft composition.

CD34+ cell subclasses and lymphocyte subsets in blood grafts collected after various mobilization methods in myeloma patients

BACKGROUND: Cyclophosphamide (CY) combined with granulocyte–colony‐stimulating factor (G‐CSF) is commonly used to mobilize stem cells in multiple myeloma (MM). Plerixafor may also be used with G‐CSF in patients who mobilize poorly or it may be added to chemomobilization to boost mobilization. Limited data are available on graft content collected after various mobilization methods.

Kinetics of blood CD34+ cells after chemotherapy plus G-CSF in poor mobilizers: Implications for pre-emptive plerixafor use

Mobilization and collection of stem cells is difficult in a proportion of patients intended for autologous stem cell transplantation (ASCT). We have evaluated mobilization kinetics of blood CD34+ cells (B-CD34+) to form basis for algorithm to facilitate rational pre-emptive plerixafor use. Altogether 390 chemomobilized patients were included. Forty-three patients (11%) did not reach B-CD34+ count ≥10 × 106/l. Mobilization kinetics differed according to the mobilization capacity observed. Among those who were very poor or inadequate mobilizers (peak B-CD34+ count ≤5 × 106/l and 6–10 × 106/l, respectively), B-CD34+ counts rarely rose after white blood cells (WBC) >5–10 × 109/l, whereas in many standard mobilizers a later rise in CD34+ counts could be observed. Four algorithms based on WBC and CD34+ counts were constructed. According to this patient series, algorithm II (WBC >5 × 109/l and B-CD34+ ≤10 × 106/l) and algorithm IV (WBC >10 × 109/l and B-CD34+ ≤10 × 109/l) were the most applicable. For algorithm II the sensitivity was 0.97 and specificity 1.00, respectively, to identify patients for plerixafor use provided that all patients with B-CD34+ maximum ≤10 × 106/l would have needed plerixafor. This simple model needs a prospective validation.

Engraftment and outcome after autologous stem cell transplantation in plerixafor-mobilized non-Hodgkin's lymphoma patients

Plerixafor is used in combination with granulocyte–colony‐stimulating factor to enhance the mobilization of hematopoietic stem cells. Limited data are available in regard to effects of plerixafor on posttransplant outcomes in chemomobilized patients who appear to mobilize poorly.

Biomarkers for bacteremia and severe sepsis in hematological patients with neutropenic fever: multivariate logistic regression analysis and factor analysis

Abstract We compared biomarkers and their changes as predictors for bacteremia and severe sepsis during neutropenic fever after intensive chemotherapy in hematological patients. Serum C-reactive protein (CRP), semi-quantative procalcitonin, aminoterminal pro-brain natriuretic peptide (NT-proBNP), cortisol, lactate, plasma antithrombin and fibrinogen were measured daily from day 0 to day 3/day 4 in 89 neutropenic fever episodes of 65 hematological patients. The best predictors for bacteremia and gram-negative bacteremia were procalcitonin and its change, with odds ratios (ORs) and 95% confidence intervals of 2.63 (1.56–4.44) and 3.20 (1.77–5.80) for bacteremia and 4.14 (2.00–8.58) and 5.04 (2.18–11.63) for gram-negative bacteremia, respectively. For severe sepsis, the best predictors were CRP and fibrinogen, with ORs of 1.94 (1.07–3.52) and 1.92 (1.05–3.54). Factor analysis provided two predictive factors: procalcitonin–NT-proBNP–antithrombin factor predicted gram-negative bacteremia and CRP–fibrinogen predicted severe sepsis. Applying a combination of markers reflecting different aspects of infection might improve the recognition of risk for complications in patients with neutropenic fever.

Blood graft cellular composition and posttransplant recovery in non-Hodgkin's lymphoma patients mobilized with or without plerixafor: a prospective comparison

Autologous stem cell transplantation is commonly used to treat non‐Hodgkins lymphomas (NHLs). Cellular composition of the blood grafts apparently has a role in the posttransplant hematologic and immune recovery. Plerixafor increases the mobilization of CD34+ cells and higher amounts of various lymphocyte subsets have been reported in the grafts. Limited prospective data are available in regard to graft cellular composition, hematologic and immune recovery, and patient outcomes in NHL patients who receive plerixafor added to chemomobilization.