Successful allogeneic transplantation of T-cell-depleted bone marrow from closely HLA-matched unrelated donors

Genetically engineered T cells for cancer immunotherapy

T cells in the immune system protect the human body from infection by pathogens and clear mutant cells through specific recognition by T cell receptors (TCRs). Cancer immunotherapy, by relying on this basic recognition method, boosts the antitumor efficacy of T cells by unleashing the inhibition of immune checkpoints and expands adaptive immunity by facilitating the adoptive transfer of genetically engineered T cells. T cells genetically equipped with chimeric antigen receptors (CARs) or TCRs have shown remarkable effectiveness in treating some hematological malignancies, although the efficacy of engineered T cells in treating solid tumors is far from satisfactory. In this review, we summarize the development of genetically engineered T cells, outline the most recent studies investigating genetically engineered T cells for cancer immunotherapy, and discuss strategies for improving the performance of these T cells in fighting cancers.

iNKT cell activation plus T-cell transfer establishes complete chimerism in a murine sublethal bone marrow transplant model

Transplant tolerance induction makes it possible to preserve functional grafts for a lifetime without immunosuppressants. One powerful method is to generate mixed hematopoietic chimeras in recipients by adoptive transfer of donor-derived bone marrow cells (BMCs). In our murine transplantation model, we established a novel method for mixed chimera generation using sublethal irradiation, CD40-CD40L blockade, and invariant natural killer T-cell activation. However, numerous BMCs that are required to achieve stable chimerism makes it difficult to apply this model for human transplantation. Here, we show that donor-derived splenic T cells could contribute to not only the reduction of BMC usage but also the establishment of complete chimerism in model mice. By cotransfer of T cells together even with one-fourth of the BMCs used in our original method, the recipient mice yielded complete chimerism and could acquire donor-specific skin-allograft tolerance. The complete chimeric mice did not show any remarks of graft versus host reaction in vivo and in vitro. Inhibition of the apoptotic signal resulted in increase in host-derived CD8⁺ T cells and chimerism brake. These results suggest that donor-derived splenic T cells having veto activity play a role in the depletion of host-derived CD8⁺ T cells and the facilitation of complete chimerism.

Nephrotic Syndrome After Hematopoietic Stem Cell Transplant: Outcomes in Iran

OBJECTIVES

Patients undergoing hematopoietic stem cell transplant have an elevated incidence of acute renal failure. However, the incidence of nephritic syndrome due to graft-versus-host disease is growing and is independently associated with chronic renal disease after this procedure.

MATERIALS AND METHODS

We conducted a prospective study to examine the risk of chronic kidney disease in glomerulopathy patients following hematopoietic stem cell transplant with a follow-up of 10 years.

RESULTS

In our follow-up of 14 patients (4 men and 10 women) who were diagnosed with nephrotic syndrome after hematopoietic stem cell transplant, in 10 patients (71%), biopsy showed membranous nephropathy associated with graft-versus-host disease. The remaining 4 patients had focal segmental glomerulosclerosis, membranoproliferative glomerulonephritis, or minimal change disease. All patients were treated with angiotensin receptor blockers, cyclosporine (Neoral), and prednisolone. During follow-up, 6 patients (43%) had heavy proteinuria and a rise in serum creatinine, and 1 patient (7%) needed hemodialysis. Eleven patients (79%) achieved complete remission of nephrotic syndrome, 5 (36%) remained hypertensive, and 3 (21%) did not respond to therapy..

CONCLUSIONS

The early diagnosis of nephrotic syndrome should be considered after hematopoietic stem cell transplant, and therapeutic outcome measures should be in place in advance. If this is done, we found that patients' response to treatment can be optimal, and their renal function and overall survival can improve.

Hematopoietic stem cell transplantation and acute kidney injury in children: A comprehensive review

AKI in the setting of HSCT is commonly investigated among adult patients. In the same way, malignancies requiring treatment with HSCT are not limited to the adult patient population, AKI following HSCT is frequently encountered within pediatric patient populations. However, inadequate information regarding epidemiology and pathophysiology specific to pediatric patients prevents development of appropriate and successful therapeutic strategies for those afflicted. Addressing AKI in the context of sinusoidal obstruction syndrome, chemotherapy, thrombotic microangiopathy and hypertension post chemotherapy, glomerulonephritis, and graft versus host disease provides greater insight into renal impairment associated with these HSCT-related ailments. To obtain a better understanding of AKI among pediatric patients receiving HSCT, we investigated the current literature specifically addressing these areas of concern.

Clinical effect of reduced-intensity conditioning regimen containing antithymocyte globulin for hematopoietic cell transplantation from unrelated-donors

The impact of reduced-intensity conditioning (RIC) on the outcomes of hematopoietic cell transplantation (HCT) from unrelated -donors (UD) remains to be determined. We therefore assessed 128 patients, aged 16 to 66 years, with acute leukemia (n = 105) or myelodysplastic syndrome (n = 23) in a UD-HCT trial using RIC with busulfan, fludarabine, and antithymocyte globulin. Patients were transplanted with unmanipulated bone marrow (BM, n = 41) or mobilized peripheral blood mononuclear cells (M-PB, n = 87) and received cyclosporine and methotrexate for graft-versus-host disease (GVHD) prophylaxis. After a median follow-up of 26.7 months (range, 5.9-70.7 months) in surviving patients, 19 patients had died without progression/recurrence of underlying disease, giving a cumulative incidence of transplantation-related mortality (TRM) of 17% (95% confidence interval, 11%-27%; 1-year TRM, 14%). Graft failure (n = 7) and infections (n = 5) were the most common causes of TRM. Only three patients died due to GVHD (acute, one; chronic, two). Graft failure, which occurred in eight patients, showed a significant correlation with graft source (BM, 6/41 vs. M-PB, 2/87; P = 0.009). Donor-patient HLA-disparity did not correlate with GVHD, 1-year TRM, and graft failure. RIC containing antithymocyte globulin led to decreased GVHD-associated, as well as overall, TRM after UD-HCT.

Chronic kidney disease after hematopoietic stem cell transplantation

Acute and chronic kidney diseases occur after hematopoietic stem cell transplantation. These are caused by the transplant itself, and the complications of transplant. Recent estimates show that near 15% of subjects undergoing hematopoietic stem cell transplantation will develop chronic kidney disease, which is a complication rate that can affect outcome and reduce survival. Investigation of the causes of chronic kidney disease is needed, as are ways to prevent, mitigate, and treat it.

Recent decrease in acute graft-versus-host disease in children with leukemia receiving unrelated donor bone marrow transplants

Unrelated donor (URD) bone marrow transplantation (BMT) is an effective treatment for leukemia in children, but its success is threatened by graft-versus-host disease (GVHD) and relapse. In this report, we describe the incidence of and risk factors for GVHD over time in children receiving URD BMT. We analyzed outcomes of 638 myeloablative URD BMTs performed between 1990 and 2003 to treat acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myelogenous leukemia, or myelodysplastic syndrome MDS, using the Center for International Blood and Marrow Transplant Research (CIBMTR) database. All recipients were under age 18 years and had available high-resolution HLA typing for HLA-A, -B, -C, and -DRB1. Overall, 27% of the recipients developed acute GVHD (aGVHD) grade III-IV; the risk was significantly higher in children receiving T cell-replete grafts compared with those receiving T cell-depleted grafts (odds ratio [OR] = 3.12; 95% confidence interval [CI] = 2.02 to 4.83; P < .0001). Acute GVHD significantly reduced the risk of relapse in children with ALL (OR = 0.34; 95% CI = 0.13 to 0.86; P = .0052), but not in those with AML (OR = 0.58; 95% CI = 0.22 to 2.98; P = .26). The risk of aGVHD was higher in children undergoing transplantation in 1990-1998 (n = 365) compared with those doing so in 1999-2003 (OR = 1.93; 95% CI = 1.27 to 2.91; P = .002). We conclude that outcomes have changed significantly over time, with a reduced risk of aGVHD associated with the more recent transplantations.

Graft-versus-host disease

Haemopoietic-cell transplantation (HCT) is an intensive therapy used to treat high-risk haematological malignant disorders and other life-threatening haematological and genetic diseases. The main complication of HCT is graft-versus-host disease (GVHD), an immunological disorder that affects many organ systems, including the gastrointestinal tract, liver, skin, and lungs. The number of patients with this complication continues to grow, and many return home from transplant centres after HCT requiring continued treatment with immunosuppressive drugs that increases their risks for serious infections and other complications. In this Seminar, we review our understanding of the risk factors and causes of GHVD, the cellular and cytokine networks implicated in its pathophysiology, and current strategies to prevent and treat the disease. We also summarise supportive-care measures that are essential for management of this medically fragile population.

Time-course and risk factors of hypothyroidism following allogeneic hematopoietic stem cell transplantation (HSCT) in children conditioned with fractionated total body irradiation

BACKGROUND

Hypothyroidism is a complication of hematopoietic stem cell transplantation (HSCT)1 that has been studied primarily in children after matched sibling bone marrow transplantation. Unrelated donors and umbilical cord blood (CB) are now used in transplantation, and hypothyroidism in these populations is undocumented. Children who underwent fractionated total body irradiation (fTBI) and received bone marrow or umbilical cord blood transplantation from siblings or unrelated donors were examined for hypothyroidism over time.

PROCEDURE

All children who received fTBI prior to allogeneic HSCT at The Children's Hospital (TCH), Denver between 1994 and 2002, and survived >1 year were included (N = 41 eligible; N = 33 met inclusion criteria). Probability of hypothyroidism was estimated by the Kaplan-Meier method and groups were compared using Cox's proportional hazards regression model.

RESULTS

Hypothyroidism developed in 52% of the children at a median time of 1.9 years (range 0.7-8.3 years). Primary compensated hypothyroidism was diagnosed in 94% of those affected. Children who received unrelated donor HSCT were 8.4 times more likely to develop hypothyroidism than those receiving matched sibling HSCT. Recipients of CB were 4.6 times more likely to have hypothyroidism than recipients of bone marrow.

CONCLUSIONS

There is a significant risk of developing hypothyroidism following fTBI, and allogeneic HSCT, that appears greater in recipients of unrelated donor HSCT and CB transplantation. Most of our patients who received BMT had sibling donors and the majority of CB transplants were from unrelated donors. It is difficult to determine which association is related to hypothyroidism, but the combination is significant.

Comparable outcomes after nonmyeloablative hematopoietic cell transplantation with unrelated and related donors

We sought to determine whether patients with hematologic malignancies treated by nonmyeloablative hematopoietic cell transplantation (HCT) at a single institution between December 1997 and June 2006 had worse outcomes with grafts from unrelated donors (URDs) (n = 184) compared with HLA-identical related donors (n = 221). The nonmyeloablative preparative regimen consisted of 2 Gy of total body irradiation (TBI) with (78%) or without (22%) fludarabine, along with posttransplantation mycophenolate mofetil (MMF) and cyclosporine (CSa). After adjusting for the HCT comorbidity index, relapse risk, patient age, stem cell source, preparative regimen, previous cytomegalovirus (CMV) infection, and sex mismatch of donor and recipient in multivariate analysis, we found no statistically significant differences between unrelated and related HCT recipients in terms of risk of nonrelapse mortality (NRM; hazard ratio [HR] = 0.98; 95% confidence interval = 0.6-1.6; P = .94), relapse (HR = 1.04; 95% confidence interval = 0.7-1.5; P = .82), or overall mortality (HR = 0.99; 95% confidence interval = 0.7-1.4; P = .94). Overall rates of severe acute and extensive chronic graft-versus-host disease (aGVHD, cGVHD) also were not significantly different between the 2 groups. We conclude that within the limitations of a retrospective study, these results indicate that candidates for nonmyeloablative HCT without suitable related donors may expect similar outcomes with grafts from URDs.

Acute graft versus host disease

Acute graft-versus-host disease (GVHD) occurs after allogeneic hematopoietic stem cell transplant and is a reaction of donor immune cells against host tissues. Activated donor T cells damage host epithelial cells after an inflammatory cascade that begins with the preparative regimen. About 35%-50% of hematopoietic stem cell transplant (HSCT) recipients will develop acute GVHD. The exact risk is dependent on the stem cell source, age of the patient, conditioning, and GVHD prophylaxis used. Given the number of transplants performed, we can expect about 5500 patients/year to develop acute GVHD. Patients can have involvement of three organs: skin (rash/dermatitis), liver (hepatitis/jaundice), and gastrointestinal tract (abdominal pain/diarrhea). One or more organs may be involved. GVHD is a clinical diagnosis that may be supported with appropriate biopsies. The reason to pursue a tissue biopsy is to help differentiate from other diagnoses which may mimic GVHD, such as viral infection (hepatitis, colitis) or drug reaction (causing skin rash). Acute GVHD is staged and graded (grade 0-IV) by the number and extent of organ involvement. Patients with grade III/IV acute GVHD tend to have a poor outcome. Generally the patient is treated by optimizing their immunosuppression and adding methylprednisolone. About 50% of patients will have a solid response to methylprednisolone. If patients progress after 3 days or are not improved after 7 days, they will get salvage (second-line) immunosuppressive therapy for which there is currently no standard-of-care. Well-organized clinical trials are imperative to better define second-line therapies for this disease. Additional management issues are attention to wound infections in skin GVHD and fluid/nutrition management in gastrointestinal GVHD. About 50% of patients with acute GVHD will eventually have manifestations of chronic GVHD.

Treatment of donor graft failure with nonmyeloablative conditioning of fludarabine, antithymocyte globulin and a second allogeneic hematopoietic transplantation

Graft failure is a life-threatening complication of allogeneic stem cell transplantation (SCT). We assessed the feasibility of performing a second SCT after such failure when fludarabine and antithymocyte globulin (ATG) are used for non-myeloablative conditioning and tacrolimus for graft-versus-host disease (GVHD) prophylaxis. Nine patients with SCTs for various hematologic malignancies were enrolled, eight with primary and one with secondary graft failure. The median time between the first and second SCT was 53 days. Eight patients had the same donor for their second SCT, and one had a cord blood transplant. Three patients were not evaluable because of early death; the other six had evidence of donor cell engraftment. Six of the nine patients developed acute grade II-IV GVHD, the main cause of death. Overall, we found that fludarabine and ATG conditioning before a second SCT allows engraftment of donor hematopoiesis. Future studies should include more intense GVHD prophylaxis.

Risk assessment in haematopoietic stem cell transplantation: GvHD prevention and treatment

Graft-versus-host disease (GvHD) is the major cause of transplant-related mortality and morbidity. As it is closely related to the major therapeutic principle, graft-versus-leukaemia (GvL) effect, risk assessment has to balance both risks depending on the pre-transplant status. This is clearly demonstrated when comparing the two major strategies for prevention of GvHD. While the majority of approaches aiming at T-cell depletion show efficacy in reducing acute and chronic GvHD and transplant-related mortality, T-cell depletion also affects graft-versus-leukaemia effects and thus results in a higher relapse rate. Thus, standard prophylaxis relying on calcineurin inhibitors frequently results in at least equivalent or even superior long-term disease-free survival, and the risk of relapse has to be considered when selecting regimens for prevention of GvHD. In addition to this general dilemma, drug-specific side-effects and risks have to be considered when selecting regimens for GvHD prevention and treatment.

Facilitating cells: Novel promoters of stem cell alloengraftment and donor-specific transplantation tolerance in the absence of GVHD

Bone marrow transplantation (BMT) is the treatment of choice for many hematological malignancies and immunopathologies. Unfortunately, success is often impeded by engraftment failure and graft-versus-host disease (GVHD). A rare bone marrow population known as the facilitating cell (FC) has been identified which facilitates stem cell engraftment and circumvents these obstacles in murine experimental models. This review discusses the identification and characterization of this rare population and provides an emerging portrait of FC origin, ontogeny and function. The promotion of durable stem cell engraftment in MHC disparate recipients, GVHD inhibition and tolerance induction by the FC suggests that future therapies in hematopoietic cell transplantation and tolerance induction for solid organ transplants may be significantly improved through the application of FC transplantation.

Regulatory T cells in graft-versus-host disease

Alloreactive T cells present in a bone marrow transplant are responsible for graft-vs-host disease, but their depletion is associated with impaired engraftment, immunosuppression, and loss of the graft-vs-leukemia effect. The subpopulation of CD4(+)CD25(+) immunoregulatory T cells was first identified based on its crucial role in the control of autoimmune processes, but they also play a role in alloreactive responses. Moreover, these cells could be used to develop innovative strategies in the field of transplantation and particularly to prevent graft-vs-host disease. Indeed, high numbers of CD4(+)CD25(+) immunoregulatory T cells can modulate graft-vs-host disease if administered at the same time as allogeneic hematopoietic stem cell transplantation in mice. This review discusses various important issues regarding the possible use of CD4(+)CD25(+) immunoregulatory T cells to modulate alloreactivity in hematopoietic stem cell transplantation.

Marked increased risk of Epstein-Barr virus-related complications with the addition of antithymocyte globulin to a nonmyeloablative conditioning prior to unrelated umbilical cord blood transplantation

Umbilical cord blood (UCB) is increasingly used as an alternative source of hematopoietic stem cells for transplantation for patients who lack a suitable sibling donor. Despite concerns about a possible increased risk of Epstein-Barr virus (EBV) posttransplantation lymphoproliferative disorder (PTLD) after UCB transplantation, early reports documented rates of PTLD comparable to those reported after HLA-matched unrelated marrow myeloablative (MA) transplantations. To further investigate the incidence of EBV PTLD after UCB transplantation and potential risk factors, we evaluated the incidence of EBV-related complications in 335 patients undergoing UCB transplantation with an MA or nonmyeloablative (NMA) preparative regimen. The incidence of EBV-related complications was a 4.5% overall, 3.3% for MA transplantations, and 7% for NMA transplantations. However, the incidence of EBV-related complications was significantly higher in a subset of patients treated with an NMA preparative regimen that included antithymocyte globulin (ATG) versus those that did not (21% vs 2%; P < .01). Nine of 11 patients who developed EBV PTLD were treated with rituximab (anti-CD20 antibody), with the 5 responders being alive and disease free at a median of 26 months. Use of ATG in recipients of an NMA preparative regimen warrants close monitoring for evidence of EBV reactivation and potentially preemptive therapy with rituximab.

Alternative donor bone marrow transplant for children with Philadelphia chromosome ALL

Children with Philadelphia chromosome positive (Ph+) acute lymphocytic leukemia (ALL) have only a 20% event-free survival when treated with chemotherapy alone. Bone marrow transplant (BMT) for patients with matched siblings has been associated with significantly better long-term survival. We asked whether children who lack a matched sibling donor would do as well if an alternative donor was utilized. Between 1987 and 2002, we transplanted 29 children and adolescents using either an unrelated donor (23) or a mismatched family member (six). The conditioning regimen included cytosine-arabinoside, cyclophosphamide and total body irradiation. Graft-versus-host disease (GVHD) prophylaxis consisted of T-cell depletion (antibody T10B9 or OKT3 and complement) with post transplant cyclosporine (CSA). All patients engrafted. Four developed grades III-IV acute GVHD. Three of 24 evaluable patients developed extensive chronic GVHD. Two patients died of relapse (7%). Two long-term survivors (>6 years) died of malignant glioblastoma multiforme. Event-free survival at 3, 5, and 10 years is 56, 51, and 46%, respectively. Five of six patients in >CR2 or relapse at the time of transplant died. Our data should encourage the use of alternative donor transplants early in the course of disease for children with Ph+ ALL.

Hematopoietic stem and progenitor cells: clinical and preclinical regeneration of the hematolymphoid system

A vast literature exists on the biology of blood formation and regeneration under experimental and clinical conditions. The field of hematopoiesis was recently advanced by the capacity to purify to homogeneity primitive hematopoietic stem and progenitor cells. Isolation of cells at defined maturational stages has enhanced the understanding of the fundamental nature of stem cells, including how cell fate decisions are made, and this understanding is relevant to the development of other normal as well as malignant tissues. This review updates the basic biology of hematopoietic stem cells (HSC) and progenitors, the evolving use of purified HSC as grafts for clinical hematopoietic cell transplantation (HCT) including immune tolerance induction, and the application of HSC biology to other stem cell fields.

Outcomes of transplantation with partial T-cell depletion of matched or mismatched unrelated or partially matched related donor bone marrow in children and adolescents with leukemias

Graft-versus-host disease (GVHD) remains a major barrier to successful hematopoietic stem cell transplant for patients who lack a matched related donor. Partial T-cell depletion (TCD) of the graft may decrease the risk of severe GVHD with unrelated donors (URD) and partially matched related donors (PMRD) while retaining an antileukemic effect. We analyzed our experience using URD and PMRD for pediatric patients with leukemias from 1990 to 2001. A subgroup of 'matched' URD donor pairs was retrospectively analyzed for high-resolution class I. Partial TCD was accomplished with monoclonal antibody T10B9 or OKT3 and complement. There were 76 URD (45% matched) and 28 PMRD recipients. Event-free survival (EFS) was 38.3%, and overall survival (OS) 45.1% at 3 years. On multivariate analysis, there was no difference in survival based upon marrow source, but nonrelapse mortality was higher with the use of PMRD. Relapse occurred in 6% of ALL patients, and 22.8% of AML/MDS patients. Grades III-IV GVHD was observed in only 6.7% of patients. Partial TCD allows use of matched or mismatched URD, or PMRD with little mortality from GVHD, durable engraftment, and no increase in relapse risk.

Life-threatening graft-vs-host disease

Hematopoietic stem cell transplant (SCT) is considered standard therapy for a variety of malignant and nonmalignant diseases. Graft-versus-host disease (GVHD) still represents today a major complication of hematopoietic SCT. Two types of GVHD have traditionally been recognized on the basis of the time of onset following transplantation, distinct pathobiological pathways, and different clinical presentations. The acute form commonly breaks out 2 to 6 weeks after transplantation, affecting up to 60% of patients receiving allogeneic transplants from HLA identical donors. Transfer of immunocompetent donor T cells contained in the graft may undergo alloreactivity against recipient cells because of major or minor histocompatibility antigens disparities between the donor and the immunosuppressed host. Target specificity in acute GVHD involves preferential injury to epithelial surfaces of the skin and mucous membranes, biliary ducts of the liver, and crypts of the intestinal tract. Chronic GVHD affects approximately 30% to 80% of patients surviving 6 months or longer after stem cell transplantation and is the leading cause of nonrelapse deaths occurring more than 2 years after transplantation. Chronic GVHD is a multiorgan syndrome with clinical features suggesting some autoimmune diseases, and possibly both alloreactive and autoreactive T cell clones are involved in its pathophysiology. Although GVHD may convey beneficial graft-versus-leukemia/lymphoma effects, it also entails a significant risk of morbidity and mortality. Patients with mild GVHD need only minimal, if any, immunosuppressive treatment, whereas prognosis of patients with extensive disease or resistant to standard immunosuppressive treatment may be dismal. Early recognition of GVHD followed by prompt therapeutic intervention may prevent the progression to higher-grade disease and improve the outcome for patients receiving hematopoietic SCT.

Chronic graft-versus-host disease

Chronic graft versus host disease (GVHD) remains today one of the most vexing late complications of allogeneic stem cell transplantation. Occurring a minimum of 100 days following stem cell transplantation, approximately 50% of patients will experience some degree of chronic GVHD. Host-reactive lymphocytes of donor origin are the cells responsible for the "alloimmune" attack. The increased use of hematopoietic stem cells collected from the peripheral blood instead of bone marrow and the increasing age of stem cell transplant recipients has led to a higher incidence of chronic GVHD. Chronic GVHD most commonly affects the skin, liver, eyes or the mouth, however multiple other sites may also be affected. Chronic GVHD and the medications used to treat it result in a profoundly immunocompromised state. Death due to severe chronic GVHD is usually a consequence of infectious complications. Standard treatment for severe chronic GVHD is a combination of cyclosporine and prednisone. An alternating day regimen of these two agents prolongs survival and reduces drug-related adverse events. Topical therapy to affected areas is preferred for patients with mild disease. The 10-year survival of patients with mild chronic GVHD is approximately 80%, but is less than 5% for patients affected by severe chronic GVHD.

CD8+ T-cell-depleted, matched unrelated donor, allogeneic bone marrow transplantation for advanced AML using busulfan-based preparative regimens

The role of T-cell depletion (TCD) to prevent graft-versus-host disease (GVHD) after matched unrelated donor allogeneic bone marrow transplant (MUD BMT) remains undefined. Most studies employ total body irradiation and pan TCD. Between March 1993 and June 2002, we treated 33 relapsed acute myelogenous leukemia (AML) patients with busulfan-based preparative regimens and selective TCD. The preparative regimen consisted of busulfan 14 mg/kg, cyclophosphamide 120 mg/kg and VP-16 50 mg/kg in all but one patient who only received busulfan and cyclophosphamide. Donor marrow was depleted of CD8+ T cells by immunomagnetic bead separation. The patients were also treated with cyclosporine and methylprednisolone or FK-506 and mini-dose methotrexate. Four (15%) of 33 patients developed graft failure or rejection. However, three of these patients were serologically mismatched at HLA-Cw. Although 67% of evaluable patients developed acute GVHD, severe grade III-IV acute GVHD only developed in 19%. The severity of acute GVHD correlated with the degree of CD8+ TCD. Median relapse-free survival was 5 months among 20 patients treated with active AML, and 28 months among 13 patients treated in complete remission. Our results confirm that MUD BMT with CD8+ TCD for AML is a potentially curative treatment option.

The Mortimer M. Bortin lecture

The graft-versus-leukemia effect of allogeneic blood or marrow transplantation is a dramatic example of the power of the immune system to eradicate malignant disease. In this personal essay, adapted from the inaugural Mortimer M. Bortin Lecture presented at the 2004 Tandem BMT Meetings, the author recounts early efforts by Bortin and others to manipulate the graft-versus-leukemia effect and separate it from the potentially fatal complications of graft-versus-host disease.

Limits of HLA mismatching in unrelated hematopoietic cell transplantation

HLA matching between the donor and recipient improves the success of unrelated hematopoietic cell transplantation (HCT). Matched donors are available for only a minority of patients. Further information is needed to evaluate the limits of HLA mismatching. We examined the association of mortality with HLA-A, -B, -C, -DRB1, and -DQB1 mismatching in 948 patients who received a T-replete unrelated HCT for treatment of a marrow disorder. A single HLA allele or antigen mismatch was associated with increased mortality among patients with chronic myeloid leukemia (CML) within 2 years after diagnosis compared to patients with no HLA mismatch, but not among those with more advanced malignancy. In particular, a single HLA-C mismatch conferred increased risk of mortality compared to matches. There was a suggestion for increased mortality with multiple mismatches involving HLA-DQB1 compared to multiple mismatches not involving HLA-DQB1. Donors with a single HLA allele or antigen mismatch may be used for HCT when a fully matched donor is not available for patients with diseases that do not permit time for a lengthy search. Whenever possible, HLA-C mismatches should be avoided for patients with early stage CML, and HLA-DQB1 mismatches should be avoided for patients with multiple mismatches.

Antiviral immunity and T-regulatory cell function are retained after selective alloreactive T-cell depletion in both the HLA-identical and HLA-mismatched settings

Nonselective T-cell depletion reduces the incidence of severe graft-versus-host disease after allogeneic hematopoietic stem cell transplantation, but the cost is delayed and disordered antigen-specific immune reconstitution and increased infection. We use a method of selective depletion of alloreactive T cells expressing the activation marker CD69 after coculture with stimulator cells in a modified or standard mixed lymphocyte reaction. The technique has been shown to reduce alloreactivity while retaining third-party responses in vitro and, in a mismatched murine model, led to donor T-cell engraftment with a virtual absence of graft-versus-host disease and increased survival. We show in a human HLA-mismatched and unrelated HLA-identical setting that this technique retains >80% of specific cellular antiviral activity by cytomegalovirus-tetramer analysis and cytomegalovirus/Epstein-Barr virus peptide-stimulated interferon-gamma ELISpot assay. Furthermore, CD4(+) CD25(+) T-regulatory cells are not removed by this method of selective allodepletion and retain their function in suppressing allogeneic proliferative responses. Preservation of antiviral cytotoxic T lymphocytes in selectively allodepleted stem cell grafts would lead to improved antiviral immunity after transplantation. The retention of immunosuppressive CD4(+) CD25(+) T-regulatory cells could lead to more ordered immune reconstitution and further suppress alloreactive responses after transplantation.

Immunoablative reduced-intensity stem cell transplantation: potential role of donor Th2 and Tc2 cells

Allogeneic reduced-intensity stem cell transplantation (RISCT) decreases regimen-associated morbidity and mortality, but it is unfortunately still constrained by the same immune T-cell reactions that limit myeloablative transplantation, including graft rejection, graft-versus-host disease (GVHD), and suboptimal graft-versus-leukemia (GVL) or graft-versus-tumor (GVT) effects. Graft rejection is mediated by host T cells, whereas GVHD and GVL/GVT effects are initiated by donor T cells, and to this extent, future advances in RISCT will likely benefit from an ability to modulate both donor and host T-cell immunity. As a step in this direction, we have developed a RISCT approach that first involves chemotherapy-induced host T-cell ablation, and second involves administration of allogeneic inocula enriched for donor CD4(+) Th2 and CD8(+) Tc2 T-cell subsets that in murine studies mediate reduced GVHD. In a pilot clinical trial, "immunoablative" RISCT with human leukocyte antigen (HLA)-matched related allografts resulted in rapid and complete donor chimerism and GVL effects early post-transplant, with GVHD being the primary toxicity. Using this immunoablative RISCT approach, we are now evaluating the feasibility and safety of augmenting allografts with additional donor CD4(+) Th2 cells that are generated in vitro via CD3/CD28 costimulation in the presence of interleukin (IL)-4. We review the biology of host and donor T-cell immunity during allogeneic RISCT and discuss the strategies of host immunoablation and donor Th2 and Tc2 cell therapy as potential means to improve the clinical results in RISCT.

New advances in acute graft-versus-host disease prophylaxis

Immunocompetent donor T cells in Allogeneic Haematopoietic Stem Cell grafts mediate acute Graft versus Host Disease (GvHD), still a major cause of recipient morbidity and mortality post transplant. Despite the advent of high resolution HLA-typing and matching at HLA loci, acute GvHD remains a significant problem, even in HLA matched siblings, due primarily to minor histocompatability antigen mismatches. Treatment of GvHD remains ineffective and highly immunosuppressive and the challenge to find effective methods of prevention continues. Non selective removal of donor T cells from the graft has been proven to be effective in preventing GvHD but the beneficial effects of donor T cells, namely effective immune reconstitution and anti tumour activity, are lost. This review considers mechanisms by which acute GvHD may be prevented in the context of the current model of GvHD immunopathogenesis, with a special emphasis on the recent techniques of selective removal or destruction of donor allogeneic T cells that have been described.

Dose-dependent effects of in vivo antithymocyte globulin during conditioning for allogeneic bone marrow transplantation from unrelated donors in patients with chronic phase CML

We conducted a dose-escalation study with antithymocyte globulin (ATG) in patients undergoing unrelated donor bone marrow transplantation (URD-BMT). This study analyzes the results for 97 patients with chronic myelogenous leukemia (CML) in first chronic phase. Median age was 36 years (16-51). In all, 40 patients were transplanted within 2 years after diagnosis and 57 later during disease. ATG-S (Fresenius) 20-120 mg/kg body weight (b.w.) was given prior to transplantation. A total of 31 patients received less than 60 mg/kg b.w. and 66 patients received 60 mg/kg b.w. or more. All patients except one were grafted with bone marrow, and graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporin A and methotrexate. Graft failure did occur in one patient. Grade II-IV acute GVHD developed in 56.7% and extensive chronic GVHD in 11.3% of the patients. The relapse rate was 13.4%. With a median follow-up of 5.8 years (1.5-12.1), 5-year disease-free and overall survival for all patients were 56 and 66%, and for patients transplanted within 2 years of diagnosis it was 72 and 82%. A lower dose of ATG was a significant risk factor for poor outcome. In summary, URD-BMT remains an excellent treatment option for patients with early phase CML, if a sufficient amount of ATG is included in the preparative regimen.

Graft-versus-host disease following allogeneic transplantation from HLA-identical sibling with antithymocyte globulin-based reduced-intensity preparative regimen

Reduced-intensity conditioning (RIC) regimens are increasingly used for allogeneic stem cell transplantation (allo-SCT). RIC has been shown to allow engraftment with minimal early transplantation-related mortality (TRM). However, in the context of RIC, predictive factors for acute and chronic graft-versus-host disease (aGVHD and cGVHD, respectively) and their effect on outcome remain unknown. In this report, we analyzed the outcome of 101 high-risk patients (70 hematologic and 31 nonhematologic malignancies) who received an HLA-identical sibling allo-SCT after RIC, including fludarabine, busulfan, and antithymocyte globulin (ATG). The cumulative incidence of grade II-IV aGVHD was 36% (95% confidence interval [CI], 27%-45%), whereas the cumulative incidence of cGVHD at 2 years was 43% (95% CI, 33%-53%). In multivariate analysis, the incidence of aGVHD was significantly associated with the ATG dose infused during conditioning (P =.0005), whereas peripheral blood as stem cell source was the only predictive factor for the development of cGVHD (P =.0007). The 1-year cumulative incidences of disease progression or relapse in patients with (n = 69) and without (n = 31) GVHD (whatever its form or grade) were 30% (95% CI, 19%-41%) and 55% (95% CI, 37%-72%), respectively (P =.02), suggesting that a potent graft-versus-tumor (GVT) effect can be achieved in high-risk patients following RIC. Moreover, the GVT effect was closely associated with GVHD without an increased risk of TRM (cumulative incidence of TRM, 18% [95% CI, 10%-25%]). Collectively, these results provide a framework for the refinement of RIC approaches designed to enhance the GVT effect with an acceptable risk of GVHD.

Rectal inflammation as first manifestation of graft-vs-host disease: radiologic-pathologic findings

Graft-vs-host disease (GVHD) is a common, life-threatening complication of bone marrow transplantation that frequently involves the gastrointestinal tract. Since symptoms are typically nonspecific, radiologic examination is often performed to reach a diagnosis. To the best of our knowledge, this is the first reported radiologic description of a case of rectal involvement as the first manifestation of GVHD. The differential diagnosis of segmental rectal wall thickening in a patient following bone marrow transplantation should include GVHD.

Donor T-lymphocyte infusion for unrelated allogeneic bone marrow transplantation with CD3+ T-cell-depleted graft

In T-cell-depleted allogeneic bone marrow transplantation (TCD-BMT) using unrelated donors, the role of donor lymphocyte infusion (DLI) for survival and disease control has not been defined. In a study of 116 patients (92 matched, 24 mismatched) who received CD3+ T-cell-depleted marrow graft, sequential infusions of escalated doses of donor T lymphocytes up to 1 x 10(6) CD3+ cells/kg were prospectively investigated. T cells were administered while patients were on cyclosporine, provided >or=grade II acute graft-versus-host-disease (GVHD) had not occurred. Acute GVHD of >or=grade II occurred in 27 of 110 (25%) patients before DLI and in 39 of 79 (49%) patients after DLI. In total, 12 of 27 (44%) patients without DLI and 44 of 72 (61%) patients who received DLI developed chronic GVHD. A total of 19 patients died of GVHD, with 17 of acute and two of chronic GVHD. Overall survival (OS) and event-free survival (EFS) at 5 years were 27 and 21%, respectively. The 2-year incidence of relapse was 14%. In multivariate analysis, only chronic GVHD was a good prognostic factor for both OS: hazard ratio (HR) 1.4, P=0.04, and EFS: HR 1.6, P=0.01. Both acute and chronic GVHD were favorable prognostic factors for relapse probability: HR 1.9 for both, P=0.02, 0.01, respectively. The 1-year cumulative incidence of transplant-related mortality (TRM), excluding cases of GVHD, was 42%. The two most common causes of 1-year non-GVHD death were viral infection (9%) and idiopathic pneumonia syndrome (12%). Although the incidence of relapse was low, the study suggests that the current scheme of DLI in unrelated TCD-BMT would not improve survival unless TRM decreases significantly.

Tissue typing in support of unrelated hematopoietic cell transplantation

The success of unrelated hematopoietic cell transplantation (HCT) for the treatment of hematologic malignancies has closely paralleled development of robust typing methods for comprehensive and precise donor-recipient matching. The application of molecular methods in clinical research has led to a more complete understanding of the immunogenetic barriers involving host-vs-graft (HVG) and graft-vs-host (GVH) reactions. Along with the development of less toxic transplant regimens, advances in the prevention and treatment of graft-vs-host disease (GVHD) and in the supportive care of the transplant recipient, improved HLA matching of potential unrelated donors has led to clinical results that begin to compare favorably with that of HLA-identical sibling transplants.

Association between pretransplant Thymoglobulin and reduced non-relapse mortality rate after marrow transplantation from unrelated donors

A matched cohort study was designed to test the efficacy of polyclonal rabbit antiserum specific for human T cells (Thymoglobulin), administered in vivo on days 1-5 (2 mg/kg/day) before T cell-replete unrelated donor marrow transplantation. Thymoglobulin was given to 52 leukemic patients at Huddinge Hospital. Control patients matched for diagnosis, disease stage, age and treated with a similar regimen, apart from the omission of Thymoglobulin, were selected in Seattle during the same period (n = 104). All received conditioning with cyclophosphamide and TBI. In the study group all patients received 10 Gy single dose TBI, while the controls were given 12-14.4 Gy fractionated TBI. GVHD prophylaxis was cyclosporine and methotrexate. Patients were treated for grade I acute GVHD in the study group, and for grade II GVHD in the control group. Multivariable analyses were adjusted for patient and donor age and CMV serology, HLA matching, donor gender and marrow cell dose. Non-relapse mortality was lower in the study patients (hazard ratio = 0.30, 95% CI 0.12-0.75, P value = 0.005). The 5-year cumulative incidence of non-relapse mortality was 19% in the study cohort, and 35% in the control cohort. Overall mortality was also lower in study patients (hazard ratio 0.51, 95% CI 0.27-0.97, P value = 0.03). No significant difference in the risk of relapse was seen (P = 0.63). This suggests that Thymoglobulin during conditioning may reduce non-relapse mortality after unrelated donor marrow transplantation.

Superior survival associated with transplantation of matched unrelated versus one-antigen-mismatched unrelated or highly human leukocyte antigen-disparate haploidentical family donor marrow grafts for the treatment of hematologic malignancies: establishing a treatment algorithm for recipients of alternative donor grafts

The purpose of this study was to compare transplantation outcomes in patients with hematologic malignancies who received marrow grafts from either phenotypically matched unrelated, one-antigen-mismatched unrelated, or highly human leukocyte antigen (HLA)-disparate family donors. Between 1993 and 2000, 139 patients underwent transplantation from unrelated donors (81 matched and 58 mismatched) and 48 patients received marrow grafts from family donors that were mismatched at 2, 3, or 4 of 8 HLA loci. All patients received a standardized conditioning regimen and a graft-versus-host disease (GVHD) prophylaxis schedule with the exception of recipients of haploidentical marrow grafts, who received antithymocyte globulin after bone marrow transplantation as additional immunosuppression. There was no statistically significant difference in the rate of engraftment, or the cumulative incidences of acute and chronic GVHD between any of the 3 groups. The 2-year cumulative incidence of relapse was lower in matched unrelated patients (25%, P =.01) and mismatched unrelated patients (26%, P =.014) than in haploidentical patients (42%). Transplant-related mortality was significantly higher in recipients of mismatched unrelated grafts (45%, P =.01) and haploidentical grafts (42%, P =.001) compared with recipients of matched unrelated marrow grafts (23%). This resulted in a significantly higher probability of overall survival for matched unrelated patients (58%) versus either mismatched unrelated (34%, P =.01) or haploidentical (21%, P =.002) patients. There was no statistically significant difference in survival between patients who received mismatched unrelated grafts versus those who received haploidentical grafts. This study supports a donor selection algorithm whereby patients who lack a closely matched family donor be offered a phenotypically matched unrelated donor if available. There is no apparent advantage to using a mismatched unrelated versus a highly HLA-disparate family donor.

Effect of combined cytostatic cyclosporin A and cytolytic suicide gene therapy on the prevention of experimental graft-versus-host disease

The immunosuppressive drug cyclosporin A (CsA) represents the standard preventive treatment of graft-versus-host disease (GVHD), the main complication of allogeneic hematopoietic stem cell transplantation (HSCT). However, its efficacy is only partial and many patients develop lethal GVHD despite CsA. A strategy of genetic immunosuppression based on conditional elimination of donor T cells expressing the Herpes simplex type 1 thymidine kinase (TK) suicide gene was recently developed. In this system, ganciclovir (GCV) selectively kills dividing but not quiescent TK T cells. Since CsA is known to have a cytostatic effect on T cells, it could negatively interfere with the division-dependent TK gene therapy. We thus tested whether administration of CsA would antagonize elimination of alloreactive donor TK T cells mediated by GCV in a murine model of GVHD. In vivo experiments revealed that, contrary to GCV, CsA only transiently controlled alloactivation-induced T cell proliferation, and likewise could not prevent lethal GVHD. When T cells resumed proliferation under CsA, they were however still sensitive to GCV. Survival, as well as immune reconstitution, was excellent in mice treated with GCV alone or in combination with CsA. These observations should help to design improved suicide gene therapy trials in the field of allogeneic HSCT.

Trends in transplantation of hematopoietic stem cells from unrelated donors

Transplants of hematopoietic stem cells from unrelated donors have become feasible for patients with a growing variety of hematologic disorders. The probability of finding a suitable donor has increased because of the expansion of the network of registries containing more than seven million HLA-typed donors worldwide. The selection of compatible donors has become more effective, thanks to the discovery of new HLA alleles and the development of precise and efficient HLA typing methods using DNA technology. Improved methods for transplantation may provide the opportunity to further decrease treatment-related toxicity and improve survival.

New therapeutic modalities in the treatment of graft-versus-host disease

Acute and chronic GvHD are still a major concern in allogeneic hematopoietic stem cell transplantation, still contributing substantially to morbidity and mortality in this therapeutic procedure. Over the past decade, many advances have been made with regard to the prevention and treatment of GvHD using various drugs such as cyclosporine A, FK506, mycophenolate mofetil and/or monoclonal IL-2 receptor antagonists. Despite these measurements with regard to the prevention of acute GvHD, it is very difficult to treat these clinical conditions successfully. However, if patients do not experience any GvHD often the desired effect of graft versus leukemia (GvL) remains absent increasing the probability of a relapse, in particular, in patients transplanted, which are considered at higher risk for relapse. At the present time, new strategies in the prevention of acute GvHD are in progress in particular the use of genetic manipulated donor T cells expressing suicide genes. Further clinical and laboratory studies are required in order to improve the prevention and, in particular, the therapy of established GvHD.

Factors affecting neutrophil and platelet reconstitution following T cell-depleted bone marrow transplantation: differential effects of growth factor type and role of CD34(+) cell dose

We have performed univariate and multivariate analysis to determine the factors that affect the kinetics of neutrophil and platelet recovery in 546 recipients of T cell-depleted (TCD) marrow allografts. All patients received marrow depleted of mature CD3(+) T cells by complement-mediated lysis using T(10)B(9)-1A3 (n = 489) or Muromonab-Orthoclone OKT3 (n = 57) monoclonal antibodies. Neutrophil engraftment to 0.5 x 10(9)/1 and platelet engraftment to 20 x 10(9)/l were assessed as endpoints. Factors significantly affecting neutrophil or platelet engraftment in the univariate analysis included patient age, T cell dose, anti-thymocyte globulin use, gender, diagnosis at transplant, CMV serostatus, HLA mismatch, CD34 cell dose (n = 249), and growth factor use and type. These variables were included in the multivariate Cox proportional hazards regression model. The results showed that a faster rate of neutrophil engraftment was independently associated with CD34(+) cell dose > or = 5 x 10(6)/kg and most strongly with growth factor administration. Faster platelet engraftment was associated with transplantation for chronic leukemia, CD34(+) cell dose > or = 2 x 10(6)/kg, an HLA matched related donor, and the absence of growth factor use. G-CSF had a higher relative risk (RR) of enhancing neutrophil engraftment than GM-CSF and significantly delayed platelet engraftment. The combined use of G-CSF + GM-CSF was similar to G-CSF alone. The enhancing effect of G-CSF for neutrophil recovery was most striking for patients who engrafted to 0.5 x 10(9)/1 at or before day 12 (RR = 9.5, P < 0.0001) compared to patients who received no growth factor. Conversely, the delaying effect of G-CSF on platelet engraftment was strongest for patients engrafting on or before day 25 (RR = 0.4, P = 0.0004). Of the independent variables affecting engraftment kinetics in recipients of TCD marrow allografts only growth factor, and to a limited extent, CD34(+) cell dose can be controlled by the clinician. A higher CD34(+) cell dose enhances the rate of both neutrophil and platelet engraftment whereas for G-CSF the benefits of myeloid growth factor use in enhancing neutrophil recovery may be partly offset by a delay in platelet engraftment.

Idiopathic pneumonia syndrome after bone marrow transplantation: the role of pre-transplant radiation conditioning and local cytokine dysregulation in promoting lung inflammation and fibrosis

Pulmonary complications and graft-vs.-host disease (GVHD) remain severe threats to survival after bone marrow transplantation (BMT). Idiopathic pneumonia syndrome (IPS) accounts for nearly 50% of all the cases of interstitial pneumonitis after BMT. IPS is characterized by an early inflammatory phase followed by chronic inflammation and fibrosis of lung tissue; however, the immunopathogenesis of this disease is not yet clearly understood. This biphasic syndrome has been reported to be associated with pre-transplant radiation conditioning in some studies while others have suggested that GVHD or autoimmune phenomena may be responsible for its development. The early post-BMT phase is characterized by the presence of inflammatory cytokines whose net effect is to promote lymphocyte influx into lungs with minimal fibrosis, that leads to an acute form of graft-vs.-host reaction-mediated pulmonary tissue damage. Gradual changes over time in leucocyte influx and activation lead to dysregulated wound repair mechanisms resulting from the shift in the balance of cytokines that promote fibrosis. Using data from new animal models of IPS and information from studies of human IPS, we hypothesize that cytokine-modulated immunological mechanisms which occur during the acute and chronic phases after bone marrow transplantation lead to the development of the progressive, inflammatory, and fibrotic lung disease typical of idiopathic pneumonia syndrome.