Hematopoietic stem cell transplantation: a global perspective

Stem cell-based approaches to treating HIV infection

PURPOSE OF REVIEW

Stem cell-based strategies for treating HIV-infected individuals represent a novel approach toward reconstituting the ravaged immune system with the ultimate aim of clearing the virus from the body. Genetic modification of human hematopoietic stem cells to produce cells that are either resistant to infection, cells that produce lower amounts of infectious virus, or cells that specifically target the immune response against the virus are currently the dominant strategies under development. This review focuses on the understanding of stem cell-based approaches that are under investigation and the rationale behind such approaches.

RECENT FINDINGS

Significant progress has recently been made utilizing stem cell-based approaches to treat HIV infection. Ideally, a successful strategy would result in immune clearance of the virus from the body as well long-term restoration of overall immune responses to successfully combat everyday environmental antigens. Two recent clinical trails illustrate how new advances in stem cell-based approaches may propel this field forward to clinical reality: one that demonstrates that large-scale gene therapy trials can be performed in a conventional, reproducible manner; and one that demonstrates the utilization of a multipronged approach using lentiviral-based gene therapy vectors. These clinical trails serve as the foundation for the development of other technologies, discussed here, that are currently in preclinical development.

SUMMARY

Recent advances using stem cell-based approaches to treat HIV infection have provided the impetus for a renewed and expanded interest in the development of new cell-based strategies to treat HIV infection as well as a variety of other diseases.

Chronic graft-versus-host disease: long-term results from a randomized trial on graft-versus-host disease prophylaxis with or without anti-T-cell globulin ATG-Fresenius

Previous randomized graft-versus-host disease (GVHD)-prophylaxis trials have failed to demonstrate reduced incidence and severity of chronic GVHD (cGVHD). Here we reanalyzed and updated a randomized phase 3 trial comparing standard GVHD prophylaxis with or without pretransplantation ATG-Fresenius (ATG-F) in 201 adult patients receiving myeloablative conditioning before transplantation from unrelated donors. The cumulative incidence of extensive cGVHD after 3 years was 12.2% in the ATG-F group versus 45.0% in the control group (P < .0001). The 3-year cumulative incidence of relapse and of nonrelapse mortality was 32.6% and 19.4% in the ATG-F group and 28.2% and 33.5% in the control group (hazard ratio [HR] = 1.21, P = .47, and HR = 0.68, P = .18), respectively. This nonsignificant reduction in nonrelapse mortality without increased relapse risk led to an overall survival rate after 3 years of 55.2% in the ATG-F group and 43.3% in the control group (HR = 0.84, P = .39, nonsignificant). The HR for receiving immunosuppressive therapy (IST) was 0.31 after ATG-F (P < .0001), and the 3-year probability of survival free of IST was 52.9% and 16.9% in the ATG-F versus control, respectively. The addition of ATG-F to standard cyclosporine, methotrexate GVHD prophylaxis lowers the incidence and severity of cGVHD, and the risk of receiving IST without raising the relapse rate. ATG-F prophylaxis reduces cGVHD morbidity.

Autologous hematopoietic stem cell transplantation-what determines the outcome: an experience from North India

Limited information is available from developing countries about complications, pattern of infections, and long-term outcome of patients following high-dose chemotherapy (HDCT) and autologous blood stem cell transplantation (ASCT). Between April, 1990 and December 2009, 228 patients underwent ASCT. Patients' median age was 48 years, ranging from 11 to 68 years. There were 158 males and 70 females. Indications for transplant included multiple myeloma, n = 143; lymphoma, n = 44 (Hodgkin's, n = 25 and non-Hodgkin's, n = 19); leukemia, n = 22; and solid tumors, n = 18. Patients received HDCT as per standard protocols. Following ASCT, 175 (76.7%) patients responded; complete, 98 (43%); very good partial response, 37 (16.2%); and partial response, 40 (17.5%). Response rate was higher for patients with good Eastern Cooperative Oncology Group (ECOG) performance status (0-2 vs. 3-4, p < 0.001), pretransplant chemo-sensitive disease (p < 0.001) and those with diagnosis of hematological malignancies (p < 0.003). Mucositis, gastrointestinal, renal, and liver dysfunctions were major nonhematologic toxicities, 3.1% of patients died of regimen-related toxicities. Infections accounted for 5.3% of deaths seen before day 30. At a median follow-up of 66 months (range, 9-234 months), median overall (OS) and event-free survival (EFS) were 72 months (95% CI 52.4-91.6) and 24 months (95% CI 17.15-30.9), respectively. For myeloma, OS and EFS were 79 months (95% CI 52.3-105.7) and 30 months (95% CI 22.6-37.4), respectively. Pretransplant good performance status and achievement of significant response following transplant were major predictors of survival. Our analysis demonstrates that such procedure can be successfully performed in a developing country with results comparable to developed countries.

Cryopreservation of Human Stem Cells for Clinical Application: A Review

SUMMARY: Stem cells have been used in a clinical setting for many years. Haematopoietic stem cells have been used for the treatment of both haematological and non-haematological disease; while more recently mesenchymal stem cells derived from bone marrow have been the subject of both laboratory and early clinical studies. Whilst these cells show both multipotency and expansion potential, they nonetheless do not form stable cell lines in culture which is likely to limit the breadth of their application in the field of regenerative medicine. Human embryonic stem cells are pluripotent cells, capable of forming stable cell lines which retain the capacity to differentiate into cells from all three germ layers. This makes them of special significance in both regenerative medicine and toxicology. Induced pluripotent stem (iPS) cells may also provide a similar breadth of utility without some of the confounding ethical issues surrounding embryonic stem cells. An essential pre-requisite to the commercial and clinical application of stem cells are suitable cryopreservation protocols for long-term storage. Whilst effective methods for cryopreservation and storage have been developed for haematopoietic and mesenchymal stem cells, embryonic cells and iPS cells have proved more refractory. This paper reviews the current state of cryopreservation as it pertains to stem cells and in particular the embryonic and iPS cell.

The EBMT activity survey 2009: trends over the past 5 years

Six hundred and twenty-four centers from 43 countries reported a total of 31,322 hematopoietic SCT (HSCT) to this 2009 European Group for Blood and Marrow Transplantation (EBMT) survey with 28,033 first transplants (41% allogeneic, 59% autologous). The main indications were leukemias (31%; 92% allogeneic), lymphomas (58%; 12% allogeneic), solid tumors (5%; 6% allogeneic) and non-malignant disorders (6%; 88% allogeneic). There were more unrelated than HLA-identical sibling donors (51 vs 43%) for allogeneic HSCT; the proportion of peripheral blood as stem cell source was 99% for autologous and 71% for allogeneic HSCT. Allogeneic and autologous HSCT continued to increase by about 1000 HSCT per year since 2004. Patterns of increase were distinct and different. In a trend analysis, allogeneic HSCT increased in all World Bank Categories (P=0.01, two sided; all categories), autologous HSCT increased in middle- (P=0.01, two sided) and low-income (P=0.01, two sided) countries. EBMT practice guidelines appeared to have an impact on trend, with a clear increase in absolute numbers within the categories 'standard' and 'clinical option' for both allogeneic and autologous HSCT (P=0.01, two sided; for both allogeneic and autologous HSCT) and a clear decrease in autologous HSCT for the 'developmental' and 'generally not recommended' indications (P=0.01, two sided). These data illustrate the status and trends of HST in Europe.

Stem cell transplant for chronic myeloid leukemia in the imatinib era

Tyrosine kinase inhibitor (TKI) therapy has revolutionized the therapy of chronic myeloid leukemia (CML). Thus, while in the near past allogeneic transplantation was the curative option for CML, imatinib, nilotinib, and dasatinib have pushed transplantation to the role of salvage therapy in CML. Still, TKI therapy still fails some patients, and so the clinical challenge is to integrate transplantation in a safe and sane manner. This article reviews the data on the variables that influence outcome following transplantation, and discusses the variables to consider in determining which patients should receive transplantation and when.

How I treat late effects in adults after allogeneic stem cell transplantation

More than 25,000 allogeneic hematopoietic stem cell transplantations (allo-HCTs) are expected to be performed worldwide in 2010, a number that has been increasing yearly. With broadening indications, more options for allo-HCT, and improvement in survival, by 2020 there may be up to half a million long-term survivors after allo-HCT worldwide. These patients have increased risks for various late complications, which can cause morbidity and mortality. Most long-term survivors return to the care of their local hematologists/oncologists or primary care physicians, who may not be familiar with specialized monitoring recommendations for this patient population. The purpose of this article is to describe practical approaches to screening for and managing these late effects, with the goal of reducing preventable morbidity and mortality associated with allo-HCT.

Comparison of fixed dose pegfilgrastim and daily filgrastim after autologous stem cell transplantation in patients with multiple myeloma autografted on a outpatient basis

Different authors have explored the feasibility of autografting patients with multiple myeloma (MM) on an outpatient basis. Peg-filgrastim (PEG), a long-acting recombinant G-CSF, has similar efficacy when compared to conventional G-CSF for chemotherapy-induced neutropenia, but little is known about its use in the autologous stem-cell transplantation (ASCT) setting, namely in patients programmed to be autografted on outpatient basis. In this study, we compared therapeutic results in terms of hematopoietic recovery, non-hematologic toxicity, duration of hospitalization and percentage of hospital readmission between patients receiving either conventional G-CSF or PEG. Thirty-eight MM patients (48 autografts) received PEG, given at a single dose of 6 mg at day +5 from stem cell infusion, while 81 (113 autografts) received G-CSF from day + 2 up to stable neutrophil recovery. The conditioning regimen was high dose melphalan in all patients. The median age and the median number of CD34 + cell infused were comparable between the two groups. Overall, a second hospital admission was required in 36 procedures out of 161 (32%). Febrile neutropenia (FN) and severe mucositis were the most frequent causes of hospitalization. There was no statistically significant difference as percentage of hospital readmission is concerned: in the PEG group readmission was needed in 6 out of 48 autografts (12%) as opposed to 30 out of 113 (26%) in the G-CSF subgroup, p: 0.06. The median time of hospital stay for readmitted patients was identical for the two subgroups (9 days vs. 9 days, p: 0.94). Finally, one case of transplant related mortality occurred in the whole patient series (0.6%). In conclusion, ASCT on an outpatient basis is feasible and safe in patients with MM, the majority of whom are manageable at home. The administration of single dose PEG results in no different outcome in terms of safety and efficacy as compared to 8 days of G-CSF.

Late altered organ function in very long-term survivors after allogeneic hematopoietic stem cell transplantation: a paired comparison with their HLA-identical sibling donor

BACKGROUND

Hematopoietic stem cell transplantation has become an established procedure worldwide. Severe early and late complications are well described. Little is known about more subtle changes in general health status of very long-term survivors. The study objective was to assess health status of very long-term survivors in comparison with their respective human leukocyte antigen-identical sibling donors.

DESIGN AND METHODS

Case matched comparison in a cross-sectional cohort was performed in a tertiary university hospital and referral center for hematopoietic stem cell transplantation. Forty-four pairs of recipients and their respective donors with a very long-term (17.5 years median; 11-26 years range) follow up after allogeneic hematopoietic stem cell transplantation were included. A comparative clinical evaluation and examination of routine clinical chemistry tests was carried out.

RESULTS

Recipients more frequently had a lower Karnofsky score (P = 0.05), hypertension (P = 0.015) and dyslipidemia (P = 0.002) but were less likely to be smokers (P = 0.016). Recipients showed systematically lower glomerular filtration rates (P < 0.0001), higher liver function tests (P = 0.0004 for Aspartat-Amino-Transferase) and reduced thyroid function (P = 0.002) despite normal or near normal values, and independent of presence or absence of chronic graft-versus-host disease. Indicators of inflammation were more frequent in recipients (9 of 44) with ongoing chronic graft-versus-host disease as measured by higher C-reactive protein (P = 0.001) and higher von Willebrand factor (P = 0.002). Conclusions Clinically very long-term survivors after an allogeneic hematopoietic stem cell transplantation present more frequently with cardiovascular risk factors and with subtle signs of altered organ function compared to their sibling donors. Even minimal ongoing chronic graft-versus-host disease remains associated with elevated laboratory indicators of inflammation. The clinical significance of these findings needs to be defined.