Effect of increased dose of total body irradiation on graft failure associated with HLA-haploidentical transplantation in patients with severe haemoglobinopathies: a prospective clinical trial.

BACKGROUND: Although severe haemoglobinopathies can be cured with allogeneic blood or bone marrow transplantation, availability of matched donors and toxic effects can be problematic. We previously found that non-myeloablative haploidentical related bone marrow transplantation with post-transplantation cyclophosphamide expanded the donor pool while limiting graft-versus-host disease (GVHD). However, graft failure-albeit with full host haemopoietic recovery-occurred in 50% of patients. In this study, we investigated whether increasing total body irradiation from 200 cGy to 400 cGy would improve engraftment while maintaining the safety profile. METHODS: This study was done at Johns Hopkins Hospital (Baltimore, MD, USA). Patients aged 2-70 years receiving their first bone marrow transplant were eligible for inclusion in the study. Patients received rabbit-derived intravenous anti-thymocyte globulin 0·5 mg/kg on day -9 and 2 mg/kg on days -8 and -7, intravenous fludarabine 30 mg/m2 on days -6 to -2, intravenous cyclophosphamide 14·5 mg/kg on days -6 and -5, and total body irradiation 400 cGy administered as a single fraction on day -1. We collected unmanipulated bone marrow and infused on day 0. GVHD prophylaxis comprised intravenous cyclophosphamide 50 mg/kg per day on days 3 and 4 after transplantation, oral mycophenolate mofetil 15 mg/kg per dose (maximum 1 g) every 8 h on days 5 to 35, and oral sirolimus to maintain a level of 5-15 ng/dL for at least 1 year starting on day 5. The original planned primary objectives of this phase 2 clinical trial were transplant-related mortality and progression-free survival. However, the coverage decision by the Centers for Medicare and Medicaid Services to only provide payment for allogeneic bone marrow transplantation for patients with sickle cell disease on a clinical trial that had a comparison arm with patients not receiving bone marrow transplantation prompted the closure of this trial to accrual in 2017. Therefore, as we were unable to perform our planned statistical analysis, the primary objective was modified to evaluate engraftment, assessed by chimerism. This trial is registered with ClinicalTrials.gov, number NCT00489281. The study is closed to new participants and this is the primary analysis. FINDINGS: Between Sept 24, 2014, and Aug 1, 2017, we enrolled 17 consecutive patients: 12 (71%) with sickle cell disease and 5 (29%) with ß-thalassaemia major. The median patient age was 16 years (range 6-31, IQR 7·7-27·5). One (6%) of 17 patients had primary graft failure with recovery of host haemopoiesis. 13 (76%) of 17 patients achieved full donor chimerism and three (18%) had mixed donor-host chimerism. Five (29%) of 17 patients developed grade 2-4 acute GVHD, including four (24%) with maximal grade 2 GVHD and one (6%) with grade 3 GVHD. Chronic GVHD developed in three (18%) patients. As of their last follow-up visit, GVHD had resolved in all patients and no patients were receiving systemic GVHD therapy. All patients remained alive as of Aug 4, 2019, and the median follow-up duration was 705 days (range 355-1294; IQR 398-943). Only one (6%) of the 16 engrafted patients remained transfusion dependent, and 14 (88%) discontinued immunosuppression. INTERPRETATION: Increasing total body irradiation to 400 cGy substantially reduced graft failure while maintaining the safety of haploidentical bone marrow transplantation with post-transplantation cyclophosphamide. These results suggest that engraftment after haploidentical bone marrow transplantation for haemoglobinopathies is possible, and primary graft failure-the main problem previously reported-might be addressed by this strategy. Therefore, this curative approach should no longer be restricted to patients with HLA-matched donors. FUNDING: Maryland Stem Cell Research Fund and US National Institutes of Health.

Humoral Immune Reconstitution Kinetics after Allogeneic Hematopoietic Stem Cell Transplantation in Children: A Maturation Block of IgM Memory B Cells May Lead to Impaired Antibody Immune Reconstitution.

Although T cell immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been well studied, long-term B cell immune reconstitution remains less characterized. We evaluated humoral immune reconstitution among 71 pediatric allo-HSCT recipients. Although tetanus toxoid antibody levels were normal at 1 year after allo-HSCT, antipolysaccharide carbohydrate antibodies remained persistently low for up to 5 years. While naive B cell counts normalized by 6 months, IgM memory B cell deficiency persisted for up to 2 years (P = .01); switched memory B cell deficiency normalized by 1 year after allo-HSCT. CD4+ T cell immune reconstitution correlated with that of switched memory B cells as early as 6 months after allo-HSCT (r = .55, P = .002) but did not correlate with IgM memory B cells at any time point after allo-HSCT. Taken together, this suggests that allo-HSCT recipients have impaired antibody immune reconstitution, mainly due to IgM memory B cell maturation block, compared with more prompt T cell-dependent switched memory cell immune reconstitution. We further explored other factors that might affect humoral immune reconstitution. The use of total body irradiation was associated with lower naive B cells counts at 6 months after HSCT (P = .04) and lower IgM (P = .008) and switched (P = .003) memory B cells up to 2 years. Allo-HSCT recipients with extensive chronic graft-versus-host disease had lower IgM memory B cell counts (P = .03) up to 2 years after allo-HSCT. The use of cord blood was associated with better naive (P = .01), IgM (P = .0005), and switched memory (P = .006) B cells immune reconstitution. These findings may inform future prophylaxis and treatment strategies regarding risk of overwhelming infection, graft-versus-host disease, and post-allogeneic HSCT revaccination.

High rates of potentially infectious exposures between immunocompromised patients and their companion animals: an unmet need for education.

A cross-sectional survey of 265 adult patients with haematological malignancy, haemoglobinopathy or human immunodeficiency virus was performed to determine the potential risk of infection from animal exposures. One hundred and thirty-seven (52%) owned an animal; the majority were dogs (74%) and cats (39%), but 14% owned birds and 3% reptiles. Eighty percent engaged in behaviour with their animals that potentially put them at risk of zoonotic infections. The most frequent behaviours were picking up animal faeces 72 (52%), cleaning animal areas 69 (50%) and allowing animals to sleep in the same bed 51 (37%). Twenty-eight percent allowed the animal to lick their face. Of all patients, 80 (30%) had been bitten or scratched by an animal. Only 16% of those who owned pets could recall receiving education regarding safe behaviours around animals. These immunocompromised patients are at risk of infection through exposure to pets. Our study highlights the need for increased education of patients regarding how to remain safe around their pets.

Sibling cord blood donor program for hematopoietic cell transplantation: the 20-year experience in the Rome Cord Blood Bank.

Umbilical cord blood (UCB) represents a source of hematopoietic stem cells for patients lacking a suitably matched and readily available related or unrelated stem cell donor. As UCB transplantation from compatible sibling provides good results in children therefore directed sibling UCB collection and banking is indicated in family who already have a child with a disease potentially treatable with an allogeneic hematopoietic stem cell transplantation. Particularly, related UCB collection is recommended when the patients urgently need a transplantation. To provide access to all patients in need, we developed a "Sibling cord blood donor program for hematopoietic cell transplantation". Here we report results of this project started 20years ago. To date, in this study a total of 194 families were enrolled, a total of 204 UCB samples were successfully collected and 15 pediatric patients have been transplanted. Recently, some authors have suggested novel role for UCB other than in the transplantation setting. Therefore, future studies in the immunotherapy and regenerative medicine areas could expand indication for sibling directed UCB collection.

Mixed chimerism in haemoglobinopathies: from risk of graft rejection to immune tolerance.

Mixed chimerism (MC), the simultaneous presence of both host- and donor-derived cells in the recipient, is observed in a large proportion of patients after haematopoietic stem cell transplant (HSCT) to treat haemoglobinopathies. Detected early after transplantation, MC often moves towards complete chimerism, although sometimes it may evolve into graft rejection, especially if the proportion of donor cells is very low. However, some patients develop stable MC, defined as persistent when donor- and host-derived cells coexist for periods longer than 2 years after HSCT. Patients with persistent mixed chimerism (PMC) do not require additional red blood cell support and, regardless of the presence in some cases of an extremely low percentage of donor-derived nucleated cells in the bone marrow, their condition is clinically controlled by an incomplete but functional graft, as they express a two- to fivefold enrichment of donor-derived mature erythrocytes in the peripheral blood. These findings have tremendous implications not only in the context of allogeneic HSCT but also in the design of gene therapy trials based on the autologous transplantation of genetically modified CD34+ cells. Recent studies have shown that durable allograft tolerance has been achieved by induction of haematopoietic chimerism in clinical kidney transplantation, showing the involvement of regulatory T cells. Similarly, it has been shown that the regulatory T cells play a pivotal role in promoting and maintaining immune tolerance in patients that develop a status of PMC after HSCT for Thalassemia.

A novel reduced-intensity conditioning regimen for unrelated umbilical cord blood transplantation in children with nonmalignant diseases.

Reduced-intensity conditioning (RIC) regimens have the potential to decrease transplantation-related morbidity and mortality. However, engraftment failure has been prohibitively high after RIC unrelated umbilical cord blood transplantation (UCBT) in chemotherapy-naïve children with nonmalignant diseases (NMD). Twenty-two children with a median age of 2.8 years, many with severe comorbidities and prior viral infections, were enrolled in a novel RIC protocol consisting of hydroxyurea, alemtuzumab, fludarabine, melphalan, and thiotepa followed by single UCBT. Patients underwent transplantation for inherited metabolic disorders (n = 8), primary immunodeficiencies (n = 9), hemoglobinopathies (n = 4) and Diamond Blackfan anemia (n = 1). Most umbilical cord blood (UCB) units were HLA-mismatched with median infused total nucleated cell dose of 7.9 × 10(7)/kg. No serious organ toxicities were attributable to the regimen. The cumulative incidence of neutrophil engraftment was 86.4% (95% confidence interval [CI], 65% to 100%) in a median of 20 days, with the majority sustaining > 95% donor chimerism at 1 year. Cumulative incidence of acute graft-versus-host disease (GVHD) grades II to IV and III to IV by day 180 was 27.3% (95% CI, 8.7% to 45.9%) and 13.6% (95 CI, 0% to 27.6%), respectively. Cumulative incidence of extensive chronic GVHD was 9.1% (95% CI, 0% to 20.8%). The primary causes of death were viral infections (n = 3), acute GVHD (n = 1) and transfusion reaction (n = 1). One-year overall and event-free survivals were 77.3% (95% CI, 53.7% to 89.8%) and 68.2% (95% CI, 44.6% to 83.4%) with 31 months median follow-up. This is the first RIC protocol demonstrating durable UCB engraftment in children with NMD. Future risk-based modifications of this regimen could decrease the incidence of viral infections. (www.clinicaltrials.gov/NCT00744692).

Hemoglobin disorders: a look to the future.

In this issue of Blood, Locatelli et al compare the results of histocompatible family donor bone marrow and cord blood transplants (BMT and CBT) for severe ß thalassemia (SBT) and sickle cell disease (SCD) as experienced by the Eurocord and European Blood and Marrow Transplantation group and collaborating centers in the United States, Hong Kong, and Israel between 1994 and 2005. Obviously, many changes in medical care and particularly MHC typing occurred over that decade, so this retrospective represents a moving target, but some firm points can be made for which we are indebted to this excellent group.

Outcome of patients with hemoglobinopathies given either cord blood or bone marrow transplantation from an HLA-identical sibling.

We analyzed the outcomes of 485 patients with thalassemia major (TM) or sickle cell disease (SCD) receiving HLA-identical sibling cord blood transplantation (CBT, n = 96) or bone marrow transplantation (BMT, n = 389). Compared with patients given BMT, CBT recipients were significantly younger (median age 6 vs 8 years, P = .02), and were treated more recently (median year 2001 vs 1999, P < .01). A higher proportion of patients with TM belonging to classes II-III of the Pesaro classification received BMT (44%) compared with CBT (39%, P < .01). In comparison with patients receiving BMT (n = 259, TM; n = 130, SCD), those given CBT (n = 66, TM; n = 30, SCD) had slower neutrophil recovery, less acute graft-versus-host disease (GVHD) and none had extensive chronic GVHD. With a median follow-up of 70 months, the 6-year overall survival was 95% and 97% after BMT and CBT, respectively (P = .92). The 6-year disease-free survival (DFS) was 86% and 80% in TM patients after BMT and CBT, respectively, whereas DFS in SCD patients was 92% and 90%, respectively. The cell dose infused did not influence outcome of patients given CBT. In multivariate analysis, DFS did not differ between CBT and BMT recipients. Patients with TM or SCD have excellent outcomes after both HLA-identical sibling CBT and BMT.

Glutathione S-transferase T1-null seems to be associated with graft failure in hematopoietic SCT.

Hematopoietic SCT (HSCT) from HLA-matched donors is sometimes complicated by GVHD or graft rejection, because of mismatched mHA. This study presents data suggesting the involvement of glutathione S-transferase theta-1 (GSTT1), a phase II detoxifying enzyme encoded by GSTT1, in Ab-mediated rejection of HSCT in children with congenital hemoglobinopathies (CHs). Mismatch of GSTT1, which often features a deletion polymorphism variant, can have major consequences in solid organ transplantation outcome. In liver transplantation, it has been shown to lead to de novo hepatitis, whereas in kidney transplantation, chronic allograft rejection has been documented. In this study on 18 children with CH who underwent HSCT, five cases of graft rejection occurred, all in GSTT1-null patients, four of which featured anti-GSTT1 antibodies. The data suggest that when GSTT1-null patients are transplanted with a GSTT1-positive graft, rejection due to an Ab-mediated immune response against GSTT1 displayed on transplanted stem cells may take place. Thus, it seems that detection of anti-GSTT1 antibodies in patients with a GSTT1-null genotype before transplantation may be predictive of graft rejection in the event of a GSTT1-positive donor.

Umbilical cord blood transplantation: pros, cons and beyond.

Large body of clinical and scientific data has been generated since the first cord blood transplantation (CBT) was performed in 1989. Superior immune plasticity of CB grafts, that allows for less stringent HLA matching, is especially valuable in the face of a persistently growing need for unrelated donor (UD) transplants. Limited cell dose remains the main setback of CBT, particularly in adult population. New strategies, such as transplantation with two cord blood units or using non-myeloablative conditioning, have remarkably expanded the availability of CB transplants in adults with hematological malignancies. Clinical trials with in vitro expanded CB-derived stem cells are under way. Currently cord blood is considered a second best choice after matched bone marrow. However, results of recent international studies indicate that in particular clinical settings, such as in children with leukemia, CB may become a frontline hematopoietic stem cell (HSC) source for transplantation. Recent advances in understanding the unique biology of cord blood will further expand indications for its use in different settings, including those beyond hematopoietic stem cells transplantation (HSCT).

Costimulation blockade, busulfan, and bone marrow promote titratable macrochimerism, induce transplantation tolerance, and correct genetic hemoglobinopathies with minimal myelosuppression.

Mixed hemopoietic chimerism has the potential to correct genetic hemological diseases (sickle cell anemia, thalassemia) and eliminate chronic immunosuppressive therapy following organ transplantation. To date, most strategies require either recipient conditioning (gamma-irradiation, depletion of the peripheral immune system) or administration of "mega" doses of bone marrow to facilitate reliable engraftment. Although encouraging, many issues remain that may restrict or prevent clinical application of such strategies. We describe an alternative, nonirradiation based strategy using a single dose of busulfan, costimulation blockade, and T cell-depleted donor bone marrow, which promotes titratable macrochimerism and a reshaping of the T cell repertoire. Chimeras exhibit robust donor-specific tolerance, evidenced by acceptance of fully allogeneic skin grafts and failure to generate donor-specific proliferative responses in an in vivo graft-versus-host disease model of alloreactivity. In this model, donor cell infusion and costimulation blockade without busulfan were insufficient for tolerance induction as donor-specific IFN-gamma-producing T cells re-emerged and skin grafts were rejected at approximately 100 days. When applied to a murine beta-thalassemia model, this approach allows for the normalization of hemologic parameters and replacement of the diseased red cell compartment. Such a protocol may allow for clinical application of mixed chimerism strategies in patients with end-stage organ disease or hemoglobinopathies.

Approach to management of fever and infection in patients with primary bone marrow failure and hemoglobinopathies.

The characteristic spectrum of infections in patients with aplastic anemia, chronic neutropenic diseases, sickle cell disease, thalassemia, and other hemoglobinopathies are described. The major risk factor for infection in patients with bone marrow failure is the degree of neutropenia and monocytopenia. In patients with aplastic anemia, invasive fungal infections emerge as the major causes of mortality. Life-threatening infections are rare in patients with chronic neutropenic diseases; however, necrotizing enterocolitis due to Clostridium species may be an exception. Bacterial infections, predominantly with encapsulated bacteria, are the most common cause of death in patients with sickle cell disease, especially those who are younger than 5 years of age. Patients with thalassemia and other hemoglobinopathies are particularly susceptible to life-threatening infections with Yersinia enterocolitica as a result of iron overload or of the chelating therapy with desferrioxamine.

Immune response to chronic red blood cell transfusion.

Patients receiving chronic transfusion for aplastic anemia or hemoglobinopathy are believed to be at high risk for developing red blood cell alloantibodies, while those undergoing chemotherapy for leukemia are believed to be at low risk. To test this hypothesis, we studied the acquisition of new alloantibodies in 703 transfused patients. While none of 99 patients with lymphocytic leukemia made new antibodies, patients with myelogenous leukemia (16%), hemoglobinopathy (29%), aplastic anemia (11%), gastrointestinal bleeding (11%) or renal failure (14%) made antibodies at statistically similar rates. Lymphocytic leukemia or its treatment is characterized by a lack of immunologic response to transfusion. Patients with hemoglobinopathy or aplastic anemia do not appear at statistically significant greater risk of alloimmunization than many other patients requiring chronic transfusion. Neither intensive chemotherapy for myelogenous leukemia nor the uremia of renal failure significantly suppress the formation of blood group antibodies.

Hb Lepore and (haemo-) blastomata.

The still increasing amount of carriers and anemics by thalassemia (Th) and other Hb-pathies (approximately 4,000 among approximately 48,000 investigated people) have shown that Campania is the most affected world area by all Hb Lepre conditions. Among 161 people with heterozygous Hb Lepore we have noticed 10 cases associated with (hemo-) blastomata as follows: 2 Chr. Lymphatic Leukemia, 2 Ac. Lymphoblastic Leukemia, 1 Lymphosarcom, 1 Colon Cancer, 1 Uterin Cancer, 1 Plasmocytom, 1 Hodkgin Disease, 1 Ac. Promyelocyte Leukemia (or fatal ac. agranulocytemia?). In the literature we recently found 2 other similar cases. The incidence of such malignancies in our Hb Lepore people reaches 6%. On the contrary in the heterozygous Th. group, among 3,150 carriers, we diagnosed only 20 people with (hemo-) blastomata as follows: 12 Ac. Leukemia (9Lymphoblastic) and 8 Chr. Myeloid Leukemia, with an incidence rate of 0.6% namely a little higher than in normal people. This highly significant discrepancy rate shows an elective predisposition to (haemo-) blastomata from Leporian people.