Nonmyeloablative and Reduced-Intensity Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation: A Clinical Review

FL/GCSF/AMD3100-mobilized Hematopoietic Stem Cells Induce Mixed Chimerism With Nonmyeloablative Conditioning and Transplantation Tolerance

BACKGROUND

Mobilization of hematopoietic stem cells (HSCs) has become the preferred approach for HSC transplantation. AMD3100, a competitive inhibitor of C-X-C motif chemokine receptor-4, has been found to be a rapid mobilizing agent. The present study evaluated approaches to optimize the product collected.

METHODS

Mobilized peripheral blood mononuclear cells (mPBMCs) from B6 mice were transplanted to recipient BALB/c mice conditioned with ablative or nonmyeloablative approaches.

RESULTS

The optimal dose of AMD3100 was found to be 5.0 mg/kg. Optimal HSC mobilization was observed when AMD3100 (day 10) was coadministered with Flt3 ligand (FL) (days 1-10) and granulocyte colony-stimulating factor (GCSF) (days 4-10). There was a 228.8-fold increase of HSC with FL/GCSF/AMD3100 compared with AMD3100 treatment alone. When unmodified mPBMCs were transplanted into ablated allogeneic recipients, all recipients expired by day 40 from severe acute graft versus host disease (GVHD). When T cells were depleted from mPBMC, long-term survival and engraftment were achieved in majority of the recipients. When PBMC mobilized by FL/GCSF/AMD3100 were transplanted into recipients conditioned nonmyeloablatively with anti-CD154/rapamycin plus 100, 200, and 300 cGy of total body irradiation, 42.9%, 85.7%, and 100% of mice engrafted, respectively. Donor chimerism was durable, multilineage, and stable. Lymphocytes from mixed chimeras showed no response to host or donor antigens, suggesting functional bidirection T-cell tolerance in vitro. Most importantly, none of the engrafted mice exhibited clinical features of GVHD.

CONCLUSIONS

FL/GCSF/AMD3100 is an efficient treatment to maximally mobilize HSC. Durable engraftment and donor-specific tolerance can be achieved with mPBMC in nonmyeloablative conditioning without GVHD.

Dissecting the mechanisms involved in anti-human T-lymphocyte immunoglobulin (ATG)-induced tolerance in the setting of allogeneic stem cell transplantation - potential implications for graft versus host disease

Polyclonal anti-human thymocyte globulins (ATG) have been recently shown to significantly reduce the incidence of graft versus host disease (GVHD) post allogeneic stem cell transplantation (HSCT) from both sibling and unrelated donors. Induction of regulatory T cells has been suggested as one of the possible mechanisms. The aim of current study was to further characterize the T cell populations induced by ATG treatment and to delineate the mechanisms involved in ATG-induced tolerance. Phenotypic characterization revealed a significant increase in the expression of FoxP3, GITR, CD95, PD-1 and ICOS as well as the complement inhibitory molecules CD55, CD58 and CD59 on CD4+CD25+ T cells upon ATG treatment. Addition of ATG-treated cells to autologous and allogeneic peripheral blood mononuclear cells (PBMCs) stimulated with anti-CD3/anti-CD28 antibodies resulted in significant inhibition of proliferation. Moreover, T-cell activation and IFNγ secretion were reduced in the presence of ATG-induced Treg cells. The CD4+CD25+CD127-low Treg fraction sorted from ATG-treated culture demonstrated greater suppressive potency than negative fraction. Conditioned medium produced by ATG-treated but not IgG-treated cells contained TGFβ and suppressed T cell proliferation and activation in a TGFβ receptor-dependent manner. TGFβ receptor kinase inhibitor SB431542 interfered with the suppressive activity of ATG-primed cells, enabling partial rescue of proliferation and IFNγ secretion. Moreover, SB431542 prevented Treg phenotype induction upon ATG treatment. Altogether, our data reveal the role of TGFβ signaling in ATG-mediated immunosuppression and further support the use of ATG, a potent inducer of regulatory T cells, for prevention of GVHD post HSCT and potentially other therapeutic applications.

Graft versus host disease: what should the oculoplastic surgeon know?

PURPOSE OF REVIEW

To provide a concise review of the oculoplastic manifestations of ocular graft versus host disease (GVHD), and to discuss their management.

RECENT FINDINGS

Ocular GVHD occurs as a common immune-mediated complication of hematopoietic stem cell transplantation that presents as a Stevens-Johnson-like syndrome in the acute phase or a Sjögren-like syndrome in the chronic phase. Cicatricial conjunctivitis may be underreported in ocular GVHD. The spectrum of oculoplastic manifestations includes GVHD of the skin, cicatricial entropion, nasolacrimal duct obstruction, and lacrimal gland dysfunction. Surgical treatment is indicated for patients with significant corneal complications from entropion. Surgical approach to repair of nasolacrimal duct obstruction is presented in this review, including modified approaches for treating patients at risk for keratitis sicca. Management of the ocular graft versus host patient may require a multidisciplinary approach involving collaboration from the oculoplastic surgeon, the corneal specialist, and the stem cell transplant physician.

SUMMARY

Oculoplastic manifestations of ocular GVHD typically present as cicatricial changes in the eyelid and lacrimal system. Careful oculoplastic and corneal evaluation are necessary when considering surgical management for the ocular GVHD patient.

Pretransplant serum FT3 levels in recipients predict early non-relapse mortality after myeloablative allogeneic haematopoietic cell transplantation from matched sibling donors

OBJECTIVES

Although decreased thyroid function is negatively correlated with clinical outcomes in critically ill patients, its role in allogeneic haematopoietic cell transplantation (allo-HCT) has not been sufficiently described.

METHODS

The associations between pre-conditioning thyroid hormone concentrations and transplant-related complications in 474 adult patients with haematologic malignancies who underwent myeloablative allo-HCT were assessed.

RESULTS

A receiver-operating characteristic curve showed that the baseline serum-free triiodothyronine 3 (FT3) level had an excellent predictive value for non-relapse mortality (NRM) within 100 days in sibling HCT with an area under the curve of 0.73 [95% confidence interval (CI), 0.64-0.82]. With a cut-off value of 4.7 pmol/l, the sensitivity and specificity for early NRM were 68% and 73%, respectively. The cumulative incidences of early NRM within 100 days after sibling HCT were 14% (95% CI, 10-18%) in the low FT3 group and 6% (95% CI, 4-8%) in the high-FT3 group (p = 0.033). In multivariate analysis, a lower FT3 level was significantly associated with high early NRM (HR = 3.19, 95% CI, 1.13-9.03, p = 0.029). The difference was also significant at 3 years after HCT (24% vs. 14%, p = 0.046). Recipients with lower FT3 levels also had a trend towards a lower OS at 3 years after HCT (66% vs. 72%, p = 0.235), although the difference did not reach statistical significance.

CONCLUSION

A low FT3 level before conditioning may be a useful predictive biomarker for higher early NRM among patients undergoing myeloablative sibling transplantation.

Adoptive T-cell therapy for Leukemia

Allogeneic stem cell transplantation (alloSCT) is the most robust form of adoptive cellular therapy (ACT) and has been tremendously effective in the treatment of leukemia. It is one of the original forms of cancer immunotherapy and illustrates that lymphocytes can specifically recognize and eliminate aberrant, malignant cells. However, because of the high morbidity and mortality that is associated with alloSCT including graft-versus-host disease (GvHD), refining the anti-leukemia immunity of alloSCT to target distinct antigens that mediate the graft-versus-leukemia (GvL) effect could transform our approach to treating leukemia, and possibly other hematologic malignancies. Over the past few decades, many leukemia antigens have been discovered that can separate malignant cells from normal host cells and render them vulnerable targets. In concert, the field of T-cell engineering has matured to enable transfer of ectopic high-affinity antigen receptors into host or donor cells with greater efficiency and potency. Many preclinical studies have demonstrated that engineered and conventional T-cells can mediate lysis and eradication of leukemia via one or more leukemia antigen targets. This evidence now serves as a foundation for clinical trials that aim to cure leukemia using T-cells. The recent clinical success of anti-CD19 chimeric antigen receptor (CAR) cells for treating patients with acute lymphoblastic leukemia and chronic lymphocytic leukemia displays the potential of this new therapeutic modality. In this review, we discuss some of the most promising leukemia antigens and the novel strategies that have been implemented for adoptive cellular immunotherapy of lymphoid and myeloid leukemias. It is important to summarize the data for ACT of leukemia for physicians in-training and in practice and for investigators who work in this and related fields as there are recent discoveries already being translated to the patient setting and numerous accruing clinical trials. We primarily focus on ACT that has been used in the clinical setting or that is currently undergoing preclinical testing with a foreseeable clinical endpoint.

Complications of allogeneic hematopoietic stem cell transplantation

Infection, graft-versus-host disease (GVHD), and to a lesser extent sinusoidal obstructive syndrome (SOS) represent the major causes of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (AHSCT). During the last decade, progress in prevention and treatment of these complications led to improvement in the outcome of these patients. Despite the fact that nonmyeloablative regimens have been increasingly used in elderly patients and in patients with co-morbidities, the nonrelapse related mortality remains a challenge and long-term follow-up is required. The objective of this manuscript is to provide an updated concise review of the complications of AHSCT and of the available treatment interventions.

Bone marrow versus peripheral blood allogeneic haematopoietic stem cell transplantation for haematological malignancies in adults

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is an established treatment option for many malignant and non-malignant disorders. In the past two decades, peripheral blood stem cells replaced bone marrow as stem cell source due to faster engraftment and practicability. Previous meta-analyses analysed patients treated from 1990 to 2002 and demonstrated no impact of the stem cell source on overall survival, but a greater risk for graft-versus-host disease (GvHD) in peripheral blood transplants. As transplant indications and conditioning regimens continue to change, whether the choice of the stem cell source has an impact on transplant outcomes remains to be determined.

OBJECTIVES

To assess the effect of bone marrow versus peripheral blood stem cell transplantation in adult patients with haematological malignancies with regard to overall survival, incidence of relapse and non-relapse mortality, disease-free survival, transplant-related mortality, incidence of GvHD and time to engraftment.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 1), MEDLINE (from 1948 to February 2014), trial registries and conference proceedings. The search was conducted in October 2011 and was last updated in February 2014. We did not apply any language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing bone marrow and peripheral blood allogeneic stem cell transplantation in adults with haematological malignancies.

DATA COLLECTION AND ANALYSIS

Two review authors screened abstracts and extracted and analysed data independently. We contacted study authors for additional information. We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included nine RCTs that met the pre-defined selection criteria, involving a total of 1521 participants. Quality of data reporting was heterogeneous among the studies. Overall, the risk of bias in the included studies was low.For the primary outcome overall survival, our analysis demonstrated comparable results between bone marrow transplantation (BMT) and peripheral blood stem cell transplantation (PBSCT) (six studies, 1330 participants; hazard ratio (HR) 1.07; 95% CI 0.91 to 1.25; P value = 0.43; high-quality evidence).Disease-free survival (six studies, 1225 participants; HR 1.04; 95% CI 0.89 to 1.21; P value = 0.6; moderate-quality of evidence) and non-relapse or transplant-related mortality (three studies, 758 participants; HR 0.98; 95% CI 0.76 to 1.28; P = 0.91; high-quality evidence) were also comparable between transplantation arms.In the related-donor setting, data from two of eight studies with 211 participants (21%) indicated a higher relapse incidence in participants transplanted with bone marrow stem cells rather than peripheral blood stem cells (HR 2.73; 95% CI 1.47 to 5.08; P value = 0.001). There was no clear evidence of a difference in relapse incidence between transplantation groups in unrelated donors (HR 1.07; 95% CI 0.78 to 1.47; P value = 0.66). The difference between the donor-related and -unrelated subgroups (P-value = 0.008) was considered to be statistically significant.BMT was associated with lower rates of overall and extensive chronic GvHD than PBSCT (overall chronic GvHD: four studies, 1121 participants; HR 0.72; 95% CI 0.61 to 0.85; P value = 0.0001, extensive chronic GvHD: four studies, 765 participants; HR 0.69; 95% CI 0.54 to 0.9; P value = 0.006; moderate-quality evidence for both outcomes). The incidence of acute GvHD grades II to IV was not lower (six studies, 1330 participants; HR 1.03; 95% CI 0.89 to 1.21; P value = 0.67; moderate-quality evidence), but there was a trend for a lower incidence of grades III and IV acute GvHD with BMT than with PBSCT (three studies, 925 participants; HR 0.75; 95% CI 0.55 to 1.02; P value = 0.07; moderate-quality evidence).Times to neutrophil and platelet engraftment were longer with BMT than with PBSCT (neutrophil: five studies, 662 participants; HR 1.96; 95% CI 1.64 to 2.35; P value < 0.00001; platelet: four studies, 333 participants; HR 2.17; 95% CI 1.69 to 2.78; P value < 0.00001).

AUTHORS' CONCLUSIONS

This systematic review  found high-quality evidence that overall survival following allo-HSCT using the current clinical standard stem cell source - peripheral blood stem cells - was similar to that following allo-HSCT using bone marrow stem cells in adults with haematological malignancies. We found moderate-quality evidence that PBSCT was associated with faster engraftment of neutrophils and platelets, but a higher risk of GvHD (in terms of more overall and extensive chronic GvHD). There was an imprecise effect on relapse and on severe (grades III to IV) acute GvHD. Quality of life, which is severely affected by GvHD, was not evaluated.Against the background of transplantation practices that have clearly changed over the past 10 to 15 years, our aim was to provide current data on the best stem cell source for allo-HSCT, by including the results of recently conducted trials. Our review includes participants recruited up to 2009, a proportion of whom were older, had received reduced-intensity conditioning regimens or had been transplanted with stem cells from unrelated donors. However, only one, large, study included relatively recently treated participants. Nevertheless, our findings are comparable to those of previous meta-analyses suggesting that our results hold true for today's practice.

Lowering the alemtuzumab dose in reduced intensity conditioning allogeneic hematopoietic cell transplantation is associated with a favorable early intense natural killer cell recovery

BACKGROUND AIMS

The anti-CD52 monoclonal antibody alemtuzumab is employed in allogeneic hematopoietic cell transplantation (alloHCT) for the prevention of graft-versus-host disease (GVHD). However, its optimal dosing in this setting has not been determined yet. We compared three different alemtuzumab dose levels in reduced intensity conditioning (RIC) alloHCT with respect to lymphocyte recovery and outcome.

METHODS

In 127 consecutive patients with predominantly advanced stage hematologic malignancies, a first alloHCT after RIC was performed, applying a fludarabine-based protocol (in 93% FBM: fludarabine, bis-chloroethyl-nitrosourea [BCNU], and melphalan). For GVHD prophylaxis, cyclosporine and alemtuzumab at three different dose levels (40 mg, 20 mg, 10 mg) were administered. Recovery of the peripheral blood (PB) lymphocyte sub-populations and clinical outcome were determined with regard to the alemtuzumab dose.

RESULTS

Natural killer (NK) cell concentrations in PB around day +30 correlated inversely with the alemtuzumab dose, whereas other PB lymphocyte subtypes remained essentially unaffected by dosing of alemtuzumab. Lower alemtuzumab doses were associated with a tendency toward improved overall survival mainly during the early post-transplantation months. With regard to the PB NK cell concentration around day +30, "early intense NK cell reconstituters" tended to show an overall survival benefit.

CONCLUSIONS

An alemtuzumab dose reduction to only 10-20 mg provides sufficient GVHD prophylaxis and supports improved NK cell regeneration early after alloHCT in PB ("NK cell saving effect"), which may have a positive effect on overall survival.

Secondary malignancies after allogeneic hematopoietic stem cell transplantation using reduced-intensity conditioning and outpatient conduction

BACKGROUND

Patients given allogeneic hematopoietic stem cell transplants (HSCT) may develop secondary malignant neoplasms (SMN). Several variables have been identified but there are no data about the incidence of this complication in individuals given HSCT using reduced-intensity conditioning (RIC) methods.

OBJECTIVE

Define the incidence of SMN in patients given HSCT using a RIC preparative regimen conducted on an outpatient basis.

MATERIALS AND METHODS

Patients given HSCT in two institutions between October 1998 and 2012 were analyzed. To appraise the SMN appearance, those patients dead were also regarded as censored at that moment, as well as those lost to follow up and those alive at the closing of the study. 95% Confidence intervals (CI) for the survival or failure estimate were calculated with the Greenwood's method.

RESULTS

A total of 416 allografted patients with a Karnofsky performance index of 100% were included in the study. All patients received peripheral blood stem cells allografts. The conditioning regimen was delivered as an outpatient procedure in all individuals. No patient was given radiotherapy nor antithymocyte globulin during the conditioning. Three hundred and sixty five patients (88%) were never admitted to the hospital, whereas 12% were admitted because of grade III-IV acute graft versus host disease (aGVHD), fever, or mucositis. Median survival time was 15.7 months. Survival at 6 months (95% CI): 66.4% (61.5-70.8%), at 12 months: 53.3% (48.1-58.1%), at 60 months: 30.6% (30.5-41.5%). Eight patients with a SMN were identified in the group of 416 allografted patients, SMN rates (95% CI) were: one year post graft: 1.9% (0.7-4.9%), 5 years: 3.8% (1.6-9.2%), 10 years: 6.8% (2.6-17.7%) and 13 years post-graft: 20.2% (5.5-59.2%), the cumulative probability of SMN being 6.8 at 10 years. Since the number of expected cases in the general population is 0.62, the ratio of observed to expected cases is 12.9 (P < 0.001). This figure means that the risk of developing a malignant neoplasm in allografted individuals using our method is 12.9 times higher than that in the general population. There were three non-Hodgkin's lymphomas, two M2 acute myelogenous leukemias, one hairy cell leukemia, one tongue epidermoid carcinoma, and one breast carcinoma.

CONCLUSIONS

We have found a low incidence of SMN in this group of Mexican patients allografted with the Mexican RIC method. Possible explanations for this difference are discussed, focusing on the RIC preparative regimen.

Transient liver function abnormality following treatment with rabbit antithymocyte globulin for nonmyeloablative hematopoetic stem cell transplant: Two case reports

Rabbit antithymocyte globulin (rATG) is increasingly used in nonmyeloablative hematopoetic stem cell transplant (HSCT). Elevated liver function tests (LFTs) have been reported for antithymocyte globulin in the treatment of aplastic anemia, but not when used in a conditioning regimen for HSCT. We describe two cases of patients receiving a conditioning regimen for HSCT containing rATG who developed a transient, severe transaminase elevation. In the first case, a 66-year-old woman with a history of acute myeloid leukemia received the first dose of rATG and the patient’s transaminases were found to be extremely elevated within a few hours. The aspartate transaminase (AST) peaked at 1286 U/L and alanine transaminase (ALT) peaked at 991 U/L and both resolved within a week. In the second case, a 72-year-old woman with a history of non-Hodgkin lymphoma received the first dose of rATG and the AST and ALT were found to be 1212 U/L and 689 U/L, respectively, 1 h after finishing the infusion. Like the previous case, the transaminase elevation resolved within a week. LFT abnormalities induced by rATG during conditioning therapy for HSCT may be transient and have a rapid onset after the first dose, but quickly subside without any complications or sequelae. It is important to follow the LFTs closely, as well as monitor for any signs and symptoms of acute liver failure.

Promising role of reduced-toxicity hematopoietic stem cell transplantation (PART-I)

Allogeneic hematopoietic stem cell transplantation (HSCT) remains a potential curative option for many patients with hematological malignancies (HM). However, the high rate of transplantation-related mortality (TRM) restricted the use of standard myeloablative HSCT to a minority of young and fit patients. Over the past few years, it has become evident that the alloreactivity of the immunocompetent donor cells mediated anti-malignancy effects independent of the action of high dose chemoradiotherapy. The use of reduced intensity conditioning (RIC) regimens has allowed a graft-versus-malignancy (GvM) effect to be exploited in patients who were previously ineligible for HSCT on the grounds of age and comorbidity. Retrospective analysis showed that RIC has been associated with lower TRM but a higher relapse rate leading to similar intermediate term overall and progression-free survivals when compared to standard myeloablative HSCT. However, the long term antitumor effect of this approach is less well established. Prospective studies are ongoing to define which patients might most benefit from reduced toxicity stem cell transplant (RT-SCT) and which transplant protocols are suitable for the different types of HM. The advent of RT-SCT permits the delivery of a potentially curative GvM effect to the majority of patients with HM whose outcome with conventional chemotherapy would be dismal. Remaining challenges include development of effective strategies to reduce relapse rates by augmenting GvM effects without increasing toxicity.

Indications and outcomes of reduced-toxicity hematopoietic stem cell transplantation in adult patients with hematological malignancies

Hematopoietic stem cell transplantation (HCT) utilizing non-myeloablative (NMA) and reduced-intensity conditioning (RIC) regimens (collectively referred to as reduced-toxicity HCT, RT-HCT) has become a viable therapeutic option for patients with hematological malignancies who are ineligible for standard myeloablative conditioning transplantation (MA-HCT). RT-HCT has been shown to induce stable engraftment with low toxicity, and to produce similar overall and progression-free survival (PFS) when compared to MA-HCT in acute myeloid leukemia and myelodysplastic syndrome. The best results for RT-HCT have been reported for patients with disease that is in remission, indolent and chemosensitive, and with a strong graft-versus-malignancy effect. Chronic graft-versus-host disease seems to correlate with a lower relapse rate and better PFS. RT-HCT is inferior when performed in poor risk or advanced disease, due to high relapse rates. A search for novel strategies that includes the most appropriate conditioning regimens and post-transplant immunomodulation protocols with more intensive anti-malignancy activity but limited toxicity is in progress. This review provides an update on the results of clinical studies of RT-HCT, and discusses possible indications and investigative strategies for improving the clinical outcomes of RT-HCT for the major hematological malignancies.

Perivascular, but not parenchymal, cerebral engraftment of donor cells after non-myeloablative bone marrow transplantation

Myeloablative (MyA) bone marrow transplantation (BMT) results in robust engraftment of BMT-derived cells in the central nervous system (CNS) and is neuroprotective in diverse experimental models of neurodegenerative diseases of the brain and retina. However, MyA irradiation is associated with significant morbidity and mortality and does not represent a viable therapeutic option for the elderly. Non-myeloablative (NMyA) BMT is less toxic, but it is not known if the therapeutic efficacy observed with MyA BMT is preserved. As a first step to address this important gap in knowledge, we evaluated and compared engraftment characteristics of BMT-derived monocytes/microglia using several clinically relevant NMyA pretransplant conditioning regimens in C57BL/6 mice. These included chemotherapy (fludarabine and cyclophosphamide) with or without 2 Gy irradiation, and 5.5 Gy irradiation alone. Each regimen was followed by transplantation of whole bone marrow from green fluorescent protein-expressing wild type (wt) mice. While stable hematopoietic engraftment occurred, to varying degrees, in all NMyA regimens, only 5.5 Gy irradiation resulted in significant engraftment of BMT-derived cells in the brain, where these cells were exclusively localized to perivascular, leptomeningeal, and related anatomic regions. Engraftment in retina under 5.5 Gy NMyA conditions was significantly reduced compared to MyA, but robust engraftment was identified in the optic nerve. Advancing the therapeutic applications of BMT to neurodegenerative diseases will require identification of the barrier mechanisms that MyA, but not NMyA, BMT is able to overcome.

Polyclonal anti-thymocyte globulins for the prophylaxis of graft-versus-host disease after allogeneic stem cell or bone marrow transplantation in adults

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (HSCT) is an established treatment for many malignant and non-malignant haematological disorders. Graft-versus-host disease (GVHD), a condition frequently occurring after HSCT, is the result of host tissues being attacked by donor immune cells. One strategy for the prevention of GVHD is the administration of anti-thymocyte globulins (ATG), a set of polyclonal antibodies directed against a variety of immune cell epitopes, leading to immunosuppression and immunomodulation.

OBJECTIVES

To assess the effect of ATG used for the prevention of graft-versus-host disease (GVHD) in patients undergoing allogeneic HSCT with regard to overall survival, incidence and severity of acute and chronic GVHD, incidence of relapse, incidence of infectious complications, non-relapse mortality, early mortality within 100 days of transplantation, progression-free survival, quality of life and adverse events.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 3), MEDLINE (January 1950 to February 2012), trials registries and conference proceedings. The search was conducted in October 2010 and was updated in July 2011 and February 2012. We did not apply any language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) investigating the impact of ATG on GVHD prophylaxis in adults suffering from haematological diseases and undergoing allogeneic HSCT. Treatment arms had to differ only in the addition of ATG to the standard GVHD prophylaxis regimen.

DATA COLLECTION AND ANALYSIS

Two review authors screened abstracts, extracted data and analysed the data independently. We contacted study authors for additional information.

MAIN RESULTS

We included in the meta-analysis six RCTs which met the pre-defined selection criteria, involving a total of 568 participants. Quality of data reporting was heterogeneous among these studies with a lack of detailed information in the early studies.The primary outcome of overall survival was not significantly changed by the addition of ATG for the prophylaxis of GVHD (harms ratio (HR) 0.88; 95% CI 0.67 to 1.15, P = 0.33).The incidence of treatment-requiring or severe acute GVHD (grade II to IV) was significantly lower in patients who received ATG (risk ratio (RR) 0.68; 95% CI 0.55 to 0.85, P = 0.009; number needed to treat (NNT) 8). Also, the incidence of severe acute GVHD (grade III to IV) was significantly reduced (HR 0.53; 95% CI 0.33 to 0.85, P = 0.0005; NNT 7) but comparable data were available for rabbit ATG only. However, pooled study results regarding the incidence of acute GVHD of all grades (I to IV) showed no significant benefit of ATG treatment (RR 0.89; 95% CI 0.74 to 1.06, P = 0.20).Meta-analysis of data regarding the incidence of overall chronic GVHD (both, limited and extensive) was not possible. Nevertheless, studies reporting on extensive chronic GVHD (only studies evaluating rabbit ATG) suggested a lower incidence of extensive chronic GVHD whereas others that only reported on overall chronic GVHD did not show an advantage for ATG.Pooled results regarding the incidence of relapse were not significantly different (RR 1.13; 95% CI 0.75 to 1.68, P = 0.56), as well as pooled results regarding non-relapse mortality (HR 0.82; 95% CI 0.55 to 1.24, P = 0.35).Due to the lack of comparable data, we could not perform meta-analysis of data regarding the incidence of chronic GVHD, relapse-related mortality, progression-free survival, quality of life, adverse events and engraftment.

AUTHORS' CONCLUSIONS

Our systematic review suggests that the addition of ATG during allogeneic HSCT significantly reduces the incidence of severe grades (II to IV) of acute GvHD, whereas the incidence of overall acute GVHD (grades I to IV) was not significantly lowered. This indicates a reduction of the severity but not the incidence of acute GVHD. However, this effect did not lead to a significant improvement of overall survival, which may be due to the severe potential side effects of the consecutively increased immunosuppression.Furthermore, future research is needed to clarify the effect of ATG on the incidence and severity of chronic GVHD and consequently on all aspects of quality of life.From the currently available data, no recommendation on the general use of ATG in allogeneic HSCT can be supported. Therefore, a careful consideration of the use of ATG based on the patient's condition and the risk factors of the transplantation setting should be made.

Low incidence and severity of graft-versus-host disease after outpatient allogeneic peripheral blood stem cell transplantation employing a reduced-intensity conditioning

BACKGROUND

The prevalence and features of graft-versus-host disease (GVHD) in patients receiving allografts using peripheral blood stem cells (PBSCs) after a reduced-intensity conditioning (RIC) regimen are not well known. Several features of GVHD in patients at two institutions using RIC were assessed.

METHODS

We analysed the overall survival (OS) and prevalence of GVHD in patients who underwent outpatient allogeneic PBSC transplantation after RIC between October 1998 and July 2008.

RESULTS

We included 301 patients with a median age of 30 yrs (range, 1-71 yrs). In 37 cases, allogeneic peripheral blood stem cell transplantation was indicated for non-malignant disease, and in 264 for malignant disease. The median OS was 35 months. The estimated 3-yr OS was 48%. A total of 154 patients developed GVHD: there were 64 acute, 50 chronic and 40 cases that progressed from acute to chronic. Of the 104 patients with acute GVHD (aGVHD), 40% had grade I and 60% had grades II-IV. Of the 90 patients with chronic GVHD (cGVHD), 67% had limited and 33% had extensive forms. A total of 160 patients died, 40 as a result of GVHD (24 from aGVHD and 16 from cGVHD), 50 as a result of progressive disease and 70 from diverse causes.

CONCLUSIONS

The incidence of GVHD was lower than in other series using conventional myeloablative preparative regimens. Most importantly, the severity of GVHD did not significantly affect the long-term survival.

Effects of sublethal irradiation on patterns of engraftment after murine bone marrow transplantation

Attempts to reduce the toxicity of hematopoietic stem cell transplantation have led to the use of various immunosuppressive, yet nonmyeloablative preparative regimens that often include low-dose irradiation. To determine the effects of low-dose irradiation on the dynamics of donor cell engraftment after bone marrow transplantation (BMT), we coupled standard endpoint flow cytometric analysis with in vivo longitudinal bioluminescence imaging performed throughout the early (<10 days) and late (days 10-90) post-BMT periods. To exclude the contribution of irradiation on reducing immunologic rejection, severely immune-deficient mice were chosen as recipients of allogeneic bone marrow. Flow cytometric analysis showed that sublethal doses of total body irradiation (TBI) significantly increased long-term (14 weeks) donor chimerism in the bone marrow compared with nonirradiated recipients (P < .05). Bioluminescence imaging demonstrated that the effect of TBI (P < .001) on chimerism occurred only after the first 7 days post-BMT. Flow cytometric analysis on day 3 showed no increase in the number of donor cells in irradiated bone marrow, confirming that sublethal irradiation does not enhance marrow chimerism early after transplantation. Local irradiation also significantly increased late (but not early) donor chimerism in the irradiated limb. Intrafemoral injection of donor cells provided efficient early chimerism in the injected limb, but long-term systemic donor chimerism was highest with i.v. administration (P < .05). Overall, the combination of TBI and i.v. administration of donor cells provided the highest levels of long-term donor chimerism in the marrow space. These findings suggest that the major effect of sublethal irradiation is to enhance long-term donor chimerism by inducing proliferative signals after the initial phase of homing.

Haematopoietic stem cell transplantation: current concepts and novel therapeutic strategies

INTRODUCTION

Haematopoietic stem cell transplantation (HSCT) is potentially curative for haematological diseases. New developments are improving its applicability and success. Sources of data A literature search was conducted on peripheral blood haematopoietic stem cell (PBHSC) mobilization, umbilical cord blood (UCB) transplantation, reduced intensity conditioning (RIC) and acute graft-versus-host disease (aGVHD).

AREAS OF AGREEMENT

PBHSC mobilization by granulocyte colony-stimulating factor and chemomobilization may fail in up to 30% of patients previously treated with extensive chemotherapy. New mobilization agents, notably the CXCR4 antagonist, have improved mobilization efficacy. UCB-HSCT is equally feasible in children and adults. RIC enables HSCT to be performed in patients who are elderly or with serious medical co-morbidities. RIC-HSCT is associated with increased frequency of graft failure and disease relapse. The prophylaxis and treatment of aGVHD are still problematic.

AREAS OF CONTROVERSY

Novel strategies in PBHSC mobilization, utilization of UCB-HSCT and RIC-HSCT and prophylaxis and treatment of aGVHD, have not been critically appraised or compared with conventional strategies.

AREAS TIMELY FOR DEVELOPING RESEARCH

The safety and efficacy of novel mobilization agents have to be tested in normal allogeneic donors. Methods of increasing the cell dose or efficacy of UCB should be developed, to extend its use to adults. RIC-HSCT should be compared with conventional HSCT in young patients. Continuous efforts in defining the best prophylaxis and treatment of aGVHD should be made.