Allogeneic Peripheral Blood Stem Cell Transplantation Using Reduced Intensity Versus Myeloablative Conditioning Regimens for the Treatment of Leukemia

Incidence, risk factors, and outcome of bloodstream infections during the pre-engraftment phase in 521 allogeneic hematopoietic stem cell transplantations

BACKGROUND

Bloodstream infection (BSI) after allogeneic hematopoietic stem cell transplantation (HSCT) is a well-known complication during the pre-engraftment phase. Knowledge of trends in etiology and antibiotic susceptibility of BSI is important as the time to effective antibiotic treatment is closely associated with survival in bacteremic patients with septic shock.

METHODS

BSI during the pre-engraftment phase was studied retrospectively in 521 patients undergoing HSCT at our center in 2001-2008. Incidence, risk factors, outcome, and microbiology findings were investigated and compared with BSI in a cohort transplanted during 1975-1996.

RESULTS

The incidence of at least 1 episode of BSI was 21%, the total attributable mortality of BSI was 3.3%, and crude mortality at day 120 after transplantation was 21%. The rate of gram-positive and gram-negative BSI was 80% and 13%, respectively. Gram-negative BSI was more frequent both in 2001-2004 and in 2005-2008 compared with 1986-1996 (P = 0.023 for 2001-2004, P = 0.001 for 2005-2008), with fluoroquinolone-resistant Escherichia coli as the predominant finding. BSI with viridans streptococci and E. coli occurred significantly earlier after HSCT than BSI with Enterococcus species, with median time of 4, 8, and 11 days, respectively (P < 0.01 both for viridians streptococci vs. Enterococcus species, and E. coli vs. Enterococcus species). Risk factors for BSI in multivariate analysis were transplantation from unrelated donor and cord blood as stem cell source, whereas peripheral blood as stem cell source was protective.

CONCLUSIONS

Despite low attributable mortality of BSI, crude mortality at day 120 after transplantation was 21%, indicating an association between BSI and other risk factors for death. The risk of gram-negative BSI increased over time in parallel with an increased rate of quinolone resistance. However, the incidence and attributable mortality of gram-negative BSI remained low. Thus, prophylaxis with ciprofloxacin is still deemed appropriate, but continued assessments of the risk and benefits of fluoroquinolone prophylaxis must be performed.

Advances in hematologic stem cell transplant: an update for oral health care providers

Oral supportive care is critical in the management of patients receiving hematopoietic cell transplantation (HCT). Advances in HCT, such as the use of stem cells isolated from peripheral blood instead of bone marrow, have resulted in more rapid engraftment and thus a shorter duration of pancytopenia. Reduced-intensity conditioning regimens, associated with less toxicity, make HCT available to older patients and patients with comorbidities. These new developments have led to increased transplant rates and an altered spectrum of therapy-related complications, such as mucositis, and to shifts in the prevalence and pattern of occurrence of infections and graft-versus-host disease. The purpose of this paper is to review the main principles of HCT and to update dental providers on new technologies being applied to transplantation that may influence oral complications and oral care.

Allogeneic hematopoietic stem cell transplantation in the elderly

The development of reduced intensity or non-myeloablative conditioning (NST) in preparation for allogeneic stem cell transplantation (SCT) revolutionized the field and led to reconsideration of the dogma of upper age limit that was set up by the transplant centers as an eligibility parameter. Analysis of the literature data showed that NST regimens are associated with decreased transplant related mortality, and graft-versus-host disease, in comparison with standard myeloablative conditioning, in patients above the age of 50-55 years, or in younger patients with significant comorbidities. However we have to mention, that our considerations are based on the retrospective analysis of the literature data, and that well controlled prospective randomized studies are needed in order to definitely assess the role of NST. Comorbidity indices might be proved as the most important parameters for the choice of the most proper regimen for each patient in need and should be included in future trials.

Allogeneic stem cell transplantation for patients with advanced hematological malignancies: comparison of fludarabine-based reduced intensity conditioning versus myeloablative conditioning

We compared the outcomes of allogeneic hematopoietic stem cell transplantation using reduced intensity and myeloablative conditioning for the treatment of patients with advanced hematological malignancies. A total of 75 adult patients received transplants from human leukocyte antigen-matched donors, coupled with either reduced intensity (n=40; fludarabine/melphalan, 28; fludarabine/cyclophosphamide, 12) or myeloablative conditioning (n=35, busufan/cyclophosphamide). The patients receiving reduced intensity conditioning were elderly, or exhibited contraindications for myeloablative conditioning. Neutrophil and platelet engraftment occurred more rapidly in the reduced intensity group (median, 9 days vs. 18 days in the myeloablative group, p<0.0001; median 12 days vs. 22 days in the myeloablative group, p=0.0001, respectively). Acute graft-versus-host disease (>or=grade II) occurred at comparable frequencies in both groups, while the incidence of hepatic veno-occlusive disease was lower in the reduced intensity group (3% vs. 20% in the myeloablative group, p=0.02). The overall 1-yr survival rates of the reduced intensity and myeloablative group patients were 44% and 15%, respectively (p=0.16). The results of present study indicate that patients with advanced hematological malignancies, even the elderly and those with major organ dysfunctions, might benefit from reduced intensity transplantation.

Mobilization, harvesting and selection of peripheral blood stem cells in patients with autoimmune diseases undergoing autologous hematopoietic stem cell transplantation

Peripheral blood stem cells (PBSC) were mobilized in 130 patients with autoimmune diseases undergoing autologous hematopoietic stem cell transplantation using cyclophosphamide 2 g/m(2) and either granulocyte colony-stimulating factor (G-CSF) 5 mcg/kg/day (for systemic lupus erythematosus (SLE) and secondary progressive multiple sclerosis, SPMS) or G-CSF 10 mcg/kg/day (for relapsing remitting multiple sclerosis (RRMS), Crohn's disease (CD), systemic sclerosis (SSc), and other immune-mediated disorders). Mobilization-related mortality was 0.8% (one of 130) secondary to infection. Circulating peripheral blood (PB) CD34(+) cells/microl differed significantly by disease. Collected CD34(+) cells/kg/apheresis and overall collection efficiency was significantly better using Spectra apheresis device compared to the Fenwall CS3000 instrument. Patients with SLE and RRMS achieved the lowest and the highest CD34(+) cell yields, respectively. Ex vivo CD34(+) cell selection employing Isolex 300iv2.5 apparatus was significantly more efficient compared to CEPRATE CS device. Circulating PB CD34(+) cells/microl correlated positively with initial CD34(+) cells/kg/apheresis and enriched product CD34(+) cells/kg. Mean WBC and platelet engraftment (ANC>0.5 x 10(9)/l and platelet count >20 x 10(9)/l) occurred on days 9 and 11, respectively. Infused CD34(+) cell/kg dose showed significant direct correlation with faster white blood cell (WBC) and platelet engraftment. When adjusted for CD34(+) cell/kg dose, patients treated with a myeloablative regimen had significantly slower WBC and platelet recovery compared to non-myeloablative regimens.

Hematopoietic stem cell therapy for malignant diseases

Allogeneic bone marrow or blood stem cell transplantation (SCT) has changed its face in the last two decades. The introduction of nonmyeloablative conditioning regimens has reduced procedure toxicity and allowed the application of SCT in patients and conditions in which SCT was not offered in the past. In this review we will summarize the changes and accomplishments achieved in the past years in the field of stem cell transplantation for malignant disorders.

Comparative outcomes of reduced intensity and myeloablative allogeneic hematopoietic stem cell transplantation in patients under 50 with hematologic malignancies

We have conducted a direct comparison of the outcomes of reduced intensity and myeloablative conditioning in younger adults with hematological malignancies<50 yr. One hundred and five patients received transplants from human leukocyte antigen (HLA)-matched donors, via either reduced intensity (n=35) or myeloablative conditioning (n=70). The median ages of the reduced intensity and myeloablative groups were 36 and 33 yr (p=0.014). Neutrophil engraftment (i.e. time to absolute neutrophil count>0.5x10(9)/L) occurred more rapidly in the reduced intensity group (median: 10 d; range: 0-21 d) than in the myeloablative group (median: 18 d; range: 11-38 d; p<0.0001). The incidence of grades 2-4 acute graft-vs.-host disease were similar between the reduced intensity and myeloablative groups, at 17% vs. 24% respectively (p=0.40). The cumulative incidence of day 100 non-relapse mortality was 18% in the reduced intensity group, and 21% in the myeloablative group (p=0.88). The overall two-yr survival rates were 43% in the reduced intensity group, and 35% in the myeloablative group (p=0.72). In conclusion, reduced intensity transplantation yielded outcomes comparable with those of myeloablative transplantation in patients under 50 with hematological malignancies.

Haematopoietic stem cell transplantation to treat aplastic anaemia

Aplastic anaemia (AA) consists of pancytopenia and empty bone marrow. Its incidence varies worldwide but predominates in developing countries. Diverse aetiologies are involved, with autoimmunity at the centre of the picture. For the 70% of patients with the severe and very severe forms of AA and who lack a human leukocyte antigen (HLA)-matched sibling, immunosuppressive therapy (IST) is key in treating the disease, with a remission rate close to 70%, an 80-90% 5-year survival rate in responding patients and a relapse rate close to 10%. For the 30% with a sibling donor available, haematopoietic stem cell transplant (HSCT) from bone marrow or peripheral blood has up to a 90% chance of cure, with a 5-10% graft rejection/failure rate. Patients who fail IST (25-30%) and lack a sibling donor can benefit from CD34(+)-enriched, partially T cell-depleted unrelated stem cell transplants, with a general survival rate up to 37%, the newest source of stem cells for this modality being cord blood. Non-myeloablative, irradiation-free conditioning regimens offer appreciable benefits, and new immunosuppressive agents, such as fludarabine and alemtuzumab, have been incorporated with promising preliminary results. Graft-versus-host disease, graft failure and infections remain significant challenges in HSCT for which innovative treatment strategies are being developed at present.