Timo Siitonen

Invasive fungal infections in autologous stem cell transplant recipients: a nation-wide study of 1188 transplanted patients

Abstract:  Based on small single‐centre series, the risk of invasive fungal infections (IFI) has been considered small in autologous stem cell transplant (ASCT) recipients. Purpose: To analyse epidemiological and clinical features of (IFI) among ASCT recipients in Finland 1990–2001. Patients: During the study period, 1188 adult patients received high‐dose therapy supported by ASCT in six centres. Altogether, 1112 patients (94%) received blood progenitor cells. The graft was CD34+ selected in 261 patients (22%). The major diagnostic groups were non‐Hodgkins lymphoma (n = 417), multiple myeloma (n = 395), breast cancer (n = 132) and Hodgkins lymphoma (n = 53). Results: Eighteen patients (1.5%) with IFI were identified. The incidence of proven or probable invasive aspergillosis was 0.8%, followed by candidaemia with an incidence of 0.3%. The median time to the diagnosis of IFI was 35 d (6–162) from the progenitor cell infusion. In fourteen patients (78%) IFI was diagnosed during lifetime and they were treated with antifungal therapy for a median of 50 d. Nine patients (64%) were cured. Conclusions: IFI appears to be a rare event after ASCT and Aspergillus infections seem to be predominant. These epidemiological features have an impact in planning prophylactic and empirical antifungal strategies in ASCT recipients.

An association between mitochondrial function and all-trans retinoic acid-induced apoptosis in acute myeloblastic leukaemia cells

The present study investigated whether all‐trans retinoic acid (ATRA)‐induced apoptosis in acute myeloblastic leukaemia (AML) is related to changes in mitochondrial function. Two human AML cell lines, OU‐AML‐3 and OU‐AML‐7, known to be inducible to time‐dependent apoptosis of varying degrees by ATRA, were used. Apoptosis induced by ATRA was shown to be a slow event. It was detected by the DNA electrophoretic method and cytofluorimetrical annexin V assay after 48 h exposure, and by morphology and polyADPribose polymerase (PARP) cleavage after 72 h exposure of AML cells to ATRA. The efflux of mitochondrial cytochrome c to cytosol was notable in Western blotting after 48 h exposure of the cells to ATRA and was observed before the drop in the mitochondrial membrane potential, which only took place after 72 h exposure, when measured by flow cytometry and a JC‐1 probe. The apoptotic events in mitochondria were more evident in the OU‐AML‐3 than the OU‐AML‐7 cell line. This might relate to the different bcl‐2 contents of the cell lines: the basic bcl‐2 levels of the OU‐AML‐7 cell line were almost twofold compared to that of the OU‐AML‐3 cell line, as analysed by the ELISA method. However, both of the cell lines showed progressive down‐regulation of bcl‐2, which began after 12–24 h exposure of the cells to ATRA as determined by ELISA, Western blotting and flow cytometry. The present results show that mitochondria have a role in ATRA‐induced apoptosis in AML cells and down‐regulation of bcl‐2 is related to it. In view of the previously published studies, the present results underline the fact that the timing of apoptotic events, such as fragmentation of DNA, externalization of phosphatidylserine, cytochrome c efflux, change in mitochondrial membrane potential and cleavage of PARP, are, to a notable extent, cell type and inducer‐dependent.

Late non‐relapse mortality among adult autologous stem cell transplant recipients: a nation‐wide analysis of 1482 patients transplanted in 1990–2003

Introduction:  Data on the incidence and causes of late (>100 d) non‐relapse mortality (NRM) in autologous stem cell transplant (ASCT) recipients is limited.

A cluster of Candida krusei infections in a haematological unit

BackgroundCandida krusei infections are associated with high mortality. In order to explore ways to prevent these infections, we investigated potential routes for nosocomial spread and possible clonality of C. krusei in a haematological unit which had experienced an unusually high incidence of cases.MethodsWe searched for C. krusei contamination of the hospital environment and determined the level of colonization in patients and health care workers. We also analyzed the possible association between exposure to prophylactic antifungals or chemotherapeutic agents and occurrence of C. krusei. The C. krusei isolates found were genotyped by pulsed-field electrophoresis method in order to determine possible relatedness of the cases.ResultsTwelve patients with invasive C. krusei infection and ten patients with potentially significant infection or mucosal colonization were documented within nine months. We were unable to identify any exogenic source of infection or colonization. Genetic analysis of the isolates showed little evidence of clonal transmission of C. krusei strains between the patients. Instead, each patient was colonized or infected by several different closely related genotypes. No association between medications and occurrence of C. krusei was found.ConclusionLittle evidence of nosocomial spread of a single C. krusei clone was found. The outbreak may have been controlled by cessation of prophylactic antifungals and by intensifying infection control measures, e.g. hand hygiene and cohorting of the patients, although no clear association with these factors was demonstrated.

Blood stem cell mobilization and collection in patients with chronic lymphocytic leukaemia: a nationwide analysis

Some reports suggest that blood stem cell mobilization is difficult in a proportion of patients with CLL. We evaluated this issue in a large cohort of CLL patients. One hundred and twenty-eight patients with CLL underwent blood stem cell mobilization during 1995–2005 in Finland. Ninety-five percent of the patients had received fludarabine. The most common mobilization regimen was intermediate-dose CY plus G-CSF (90 patients, 70%). At least 2 × 106/kg CD34+ cells were collected after the first mobilization attempt in 83 patients (65%), whereas 45 patients (35%) failed to reach this collection target. No differences were observed between these patient groups with regard to age, time from the diagnosis to mobilization, number of previous treatment lines, number of fludarabine courses, time from the last fludarabine-containing chemotherapy to mobilization, disease status or degree of marrow infiltration. Patients who failed collection had platelets <100 × 109/l more commonly at the time of mobilization (30 vs 4%, P<0.001). A significant proportion of patients with CLL were difficult to mobilize. Adequate marrow function including platelet counts >100 × 109/l seem to be important factors in terms of successful blood stem cell collection.

Long-term outcome of intensive chemotherapy for adults with de novo acute myeloid leukaemia (AML): the nationwide AML-92 study by the Finnish Leukaemia Group.

Objective:  To investigate the long‐term outcome of idarubicin‐ and cytarabine‐based intensive chemotherapy in adult acute myeloid leukaemia (AML).

p53-mediated downregulation of Chk1 abrogates the DNA damage-induced G2M checkpoint in K562 cells, resulting in increased apoptosis

Summary. BCR–ABL confers apoptotic resistance to a range of genotoxic agents, and this protection is mediated in part by prolonging the G2 checkpoint. The p53 tumour suppressor protein regulates the transcription of regulatory genes involved in cell cycle arrest and apoptosis. To investigate the effect of p53 on the BCR–ABL‐mediated G2M checkpoint response, we transiently transfected the BCR–ABL‐positive, p53‐negative cell line K562 with wild‐type human p53. The p53‐transfected cells showed a decreased ability to arrest in G2 and an increase in apoptosis in response to etoposide treatment, relative to the control mock‐transfected cells. p53‐transfected and control cells were treated with etoposide and trapped at mitosis with nocodazole. The mitotic index of p53‐transfected cells was higher than that of the control cells, which suggests that p53 abrogates the G2 checkpoint response to etoposide treatment in K562 cells. We found that the expression of the cell cycle checkpoint protein Chk1 was reduced in the etoposide‐treated p53‐transfected cells by 24 h, and this correlated with a reduction in the extent of etoposide‐induced phosphorylation of CDK1 at tyrosine 15 (Y15). We conclude, therefore, that p53 overrides the strong G2 checkpoint response to etoposide in K562 cells, by directly or indirectly downregulating Chk1 expression, which, in turn, contributes to the proapoptotic effect of p53.

A randomized phase II study of stem cell mobilization with cyclophosphamide+G-CSF or G-CSF alone after lenalidomide-based induction in multiple myeloma.

The most common means of mobilizing autologous stem cells is G-CSF alone or combined with cyclophosphamide (CY) to obtain sufficient CD34+ cells for one to two transplants. There are few prospective, randomized studies investigating mobilization regimens in multiple myeloma (MM), especially after lenalidomide-based induction. We designed this prospective, randomized study to compare low-dose CY 2 g/m2+G-CSF (arm A) and G-CSF alone (arm B) after lenalidomide-based up-front induction in MM. Of the 80 initially randomized patients, 69 patients were evaluable, 34 and 35 patients in arms A and B, respectively. The primary end point was the proportion of patients achieving a yield of ⩾3 × 106/kg CD34+ cells with 1−2 aphereses, which was achieved in 94% and 77% in arms A and B, respectively (P=0.084). The median number of aphereses needed to reach the yield of ⩾3 × 106/kg was lower in arm A than in arm B (1 vs 2, P=0.035). Two patients needed plerixafor in arm A and five patients in arm B (P=0.428). Although CY-based mobilization was more effective, G-CSF alone was successful in a great majority of patients to reach the defined collection target after three cycles of lenalidomide-based induction.

Autologous stem cell transplantation in patients with high-risk plasmacytoma

Abstract:  Although autologous stem cell transplantation (ASCT) is considered standard treatment in patients with multiple myeloma (MM), limited experience is available on this approach in patients with plasmacytoma (PC). Twelve patients with high‐risk PC received ASCT in Finland 1994–2002. There were nine males and three females with a median age of 50 yr (32–64). Ten patients had a PC of bone, whereas two patients had extramedullary PCs. The median time from the diagnosis to ASCT was 9 months (5–100). At the time of ASCT six patients were in first complete remission (CR) or partial remission (PR), in four patients the disease was refractory to the first line therapy and two patients had relapsed. High‐dose therapy consisted of melphalan (MEL)200 (n = 7), MEL200 × 2 (n = 3) or total body irradiation (TBI)‐MEL140 (n = 2). No transplant‐related deaths occurred. After ASCT eight patients (67%) were in CR, one patient in very good PR and one patient in PR; two patients were non‐responders. With a median follow‐up of 48 months from ASCT, 11 patients (92%) are alive. Six patients (50%) have relapsed or progressed 3–81 months from ASCT. ASCT is feasible in this patient population resulting in promising overall survival. A randomised trial is needed to assess the real value of ASCT when compared with other treatment options in patients with high‐risk PC.

Autologous stem cell transplantation in patients with primary amyloidosis: a nation-wide survey.

Due to poor prognosis with conventional therapy, high-dose therapy (HDT) with autologous stem cell transplantation (ASCT) is considered for treatment in patients with primary amyloidosis (AL). Only single centre series are available on the feasibility and efficacy of this approach. Altogether 20 AL patients (11 males, 9 females, median age 54 years) were included in HDT protocols in 5 Finnish transplant centres between 1997 and 2003. Twelve patients were mobilized with granulocyte colony-stimulating factor (G-CSF) alone and 8 patients with a combination of cyclophosphamide and G-CSF. Sixteen patients (80%) went on to high-dose melphalan. Early transplant-related mortality was 25%. Nine out of 11 evaluable patients showed improvement or stabilization of AL. The overall survival of the transplanted patients is 69% (median follow-up 13 months). After a median follow-up of 26 months for the living patients, only 2 patients (18%) have shown progression of AL. This retrospective nation-wide analysis shows that HDT with ASCT leads to improvement or stabilization of AL in the majority of the patients who survive the immediate posttransplant period. A randomized multicentre trial is needed to show whether ASCT is superior to conventional therapy in patients with AL.