Long-term follow-up of allogeneic stem cell transplantation in patients with severe aplastic anemia after conditioning with cyclophosphamide plus antithymocyte globulin

The state of the art in the treatment of severe aplastic anemia: immunotherapy and hematopoietic cell transplantation in children and adults

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure where marrow disruption is driven by a cytotoxic T-cell-mediated autoimmune attack against hematopoietic stem cells. The key diagnostic challenge in children, but also in adults, is to exclude the possible underlying congenital condition and myelodysplasia. The choice of treatment options, either allogeneic hematopoietic cell transplantation (alloHCT) or immunosuppressive therapy (IST), depends on the patient's age, comorbidities, and access to a suitable donor and effective therapeutic agents. Since 2022, horse antithymocyte globulin (hATG) has been available again in Europe and is recommended for IST as a more effective option than rabbit ATG. Therefore, an update on immunosuppressive strategies is warranted. Despite an improved response to the new immunosuppression protocols with hATG and eltrombopag, some patients are not cured or remain at risk of aplasia relapse or clonal evolution and require postponed alloHCT. The transplantation field has evolved, becoming safer and more accessible. Upfront alloHCT from unrelated donors is becoming a tempting option. With the use of posttransplant cyclophosphamide, haploidentical HCT offers promising outcomes also in AA. In this paper, we present the state of the art in the management of severe AA for pediatric and adult patients based on the available guidelines and recently published studies.

Pilot study: bone marrow stem cells as a treatment for dogs with chronic spinal cord injury

Background

Chronic Spinal Cord injury is a common, severe, and medically untreatable disease. Since the functional outcomes of acute and experimental chronic spinal cord injury have been shown to improve with stem cell therapy, a case study was conducted to test if the application of stem cell also regenerates chronic SCI dysfunction. Transplantation of foetal bone marrow stem cells was applied in seven dogs with chronic spinal cord injury. Magnetic resonance images and assessments of symptoms according to the Olby scale were used to diagnose the severity of injury.

Result

All dogs improved locomotor and sensory function when examined 90 days after surgery, and showed increased movement of the hind limbs, and were able to stand upright, as well as to take small steps. Tail tone was observed in seven dogs, pain reflexes and defecation return were observed in five dogs.

Conclusion

The transplantation of bone marrow stem may be a promising, reliable and safe treatment for chronic spinal cord injury.

Electronic supplementary material

The online version of this article (doi:10.1186/2050-490X-2-9) contains supplementary material, which is available to authorized users.

Clinical safety and primary efficacy of bone marrow mesenchymal cell transplantation in subacute spinal cord injured patients

BACKGROUND

In recent years, some studies were conducted to evaluate the effects of stem cells from different sources on patients with spinal cord injury (SCI). This study was carried out to evaluate the feasibility and therapeutic potential of autologous bone marrow cell (BMC) transplantation in 11 complete spinal cord injured patients at thoracic level.

METHODS AND MATERIALS

This nonrandomized clinical trial compared the results of autologous BMC transplantation into cerebrospinal fluid (CSF) via lumbar puncture (LP) in 11 patients having complete SCI, with 20 patients as control group who received conventional treatment without BMC transplantation. The patients underwent preoperative and follow-up neurological assessments using the American Spinal Injury Association (ASIA) impairment scale. Then, the participants were followed for 12-33 months.

RESULTS

Eleven patients with the mean age of 33.2±8.9 years and 20 patients with the mean age of 33.5±7.2 years were enrolled in the study and in the control group, respectively. None of the patients in the study and control group experienced any adverse reaction and complications, neither after routine treatment nor after cell transplantation. Five patients out of 11 (45.5%) in the study group and three patients in the control group (15%) showed marked recovery, but the result was statistically borderline (P=0.095).

CONCLUSION

We conclude that transplantation of autologous BMC via LP is a feasible and safe technique, but at the moment, no clear answer can be given regarding the clinical potential, despite a potential tendency to treat SCI patients, observed through statistics.

Late effects among pediatric patients followed for nearly 4 decades after transplantation for severe aplastic anemia

Aplastic anemia (AA), a potentially fatal disease, may be cured with marrow transplantation. Survival in pediatric patients has been excellent early after transplantation, but only limited data are available regarding late effects. This study evaluates late effects among 152 patients followed 1-38 years (median, 21.8 years). Transplantation-preparative regimes were mostly cyclophosphamide with or without antithymocyte globulin. Survival at 30 years for the acquired AA patients is 82%, and for the Fanconi anemia patients it is 58% (P = .01). Multivariate analysis demonstrated that chronic GVHD (P = .02) and Fanconi anemia (P = .03) negatively impacted survival. Two Fanconi patients and 18 acquired AA patients developed a malignancy that was fatal for 4. There was an increased incidence of thyroid function test abnormalities among those who received total body irradiation. Cyclophosphamide recipients demonstrated normal growth, basically normal development, and pregnancies with mostly normal offspring. Quality-of-life studies in adult survivors of this pediatric transplantation cohort indicated that patients were comparable with control patients except for difficulty with health and life insurance. These data indicate that the majority of long-term survivors after transplantation for AA during childhood can have a normal productive life.

Successful bone marrow transplantation for children with aplastic anemia based on a best-available evidence strategy

  A best-available evidence strategy, i.e., the best-available donors, conditioning regimens and GVHD prophylaxis were chosen at the time of BMT for AA, was analyzed retrospectively. The outcomes for 18 children with AA who underwent allogeneic BMT were analyzed. The median age was 11 yr (range 4-16), and nine were men. As conditioning regimens, seven had low-dose irradiation + CY, six had ATG + CY + Flu, and five had ATG + CY. Donors were HLA-matched siblings in 10, HLA-mismatched family in one, HLA-matched unrelated in three, and HLA-mismatched unrelated in four. As GVHD prophylaxis, three received CsA alone, nine received CsA + MTX, and six received tacrolimus + MTX. All 18 patients showed engraftment. The median number of days until the neutrophil count exceeded 500/μL was 16 (range 11-21) post-transplant. Five developed more than grade 2 acute GVHD, and three developed extensive cGVHD. One patient died because of interstitial pneumonia complicated with cGVHD. Five-yr OS was 94% (95% CI: 83-105). These results suggest that a strategy of treating patients based on the best-available evidence is acceptable.

Is it time for a change? The case for early application of unrelated allo-SCT for severe aplastic anemia

Severe aplastic anemia (SAA) is a BM failure syndrome in which allo-SCT remains a highly effective curative option. Its application remains limited by donor availability and by the potential for treatment-related morbidity and mortality. The improved outcomes with unrelated transplantation are a result of the advent of molecular donor-recipient matching, generation of effective novel conditioning regimens, improvement of supportive care and expansion of the donor registry. Decision making regarding the earlier use of unrelated transplant procedures is rapidly evolving. This paper reviews critical data relevant to these treatment options and recommends early consideration of related SCT for patients with SAA who show failure of immune suppressive therapy.

A retrospective comparison of cyclophosphamide plus antithymocyte globulin with cyclophosphamide plus busulfan as the conditioning regimen for severe aplastic anemia

Allogeneic hematopoietic stem cell transplantation (AHSCT) is the treatment of choice for young patients with severe aplastic anemia (SAA). The association of antithymocyte globulin (ATG) and cyclophosphamide (CY) is the most frequently used conditioning regimen for this disease. We performed this retrospective study in order to compare the outcomes of HLA-matched sibling donor AHSCT in 41 patients with SAA receiving cyclophosphamide plus ATG (ATG-CY, N = 17) or cyclophosphamide plus busulfan (BU-CY, N = 24). The substitution of BU for ATG was motivated by the high cost of ATG. There were no differences in the clinical features between the two groups, including age, gender, cytomegalovirus status, ABO match, interval between diagnosis and transplant, and number of total nucleated cells infused. No differences were observed in the time to neutrophil and platelet engraftment, or in the risk of veno-occlusive disease and hemorrhage. However, there was a higher risk of mucositis in the BU-CY group (71 vs 24%, P = 0.004). There were no differences in the incidence of neutrophil and platelet engraftment, acute and chronic graft-versus-host disease, and transplant-related mortality. There was a higher incidence of late rejection in the ATG-CY group (41 vs 4%, P = 0.009). Although the ATG-CY group had a longer follow-up (101 months) than the BU-CY group (67 months, P = 0.04), overall survival was similar between the groups (69 vs 58%, respectively, P = 0.32). We conclude that the association BU-CY is a feasible option to the conventional ATG-CY regimen in this population.

Allogeneic stem cell transplantation for severe aplastic anemia: graft rejection remains a problem

We reviewed the outcome in 15 consecutive patients with severe aplastic anemia with a median age of 23 years who received matched sibling peripheral blood stem cell transplantation. Conditioning regimen was cyclophosphamide (Cy)+anti-thymocyte globulin (ATG). Cumulative incidence of transplant related mortality, graft failure, acute and chronic GVHD were 20%, 33%, 25%, and 8.3%, respectively. Conditioning with Cy only, resulted in higher rejection rate compared to Cy plus ATG (75% versus 12.5%, p=0.03). Eighty percent of patients are alive with a median follow-up of 19.5 (4.6-35.6) months. Two of the three patients who were re-transplanted with fludarabine had sustained donor chimerism.

Reduced-intensity conditioning for severe aplasia using fludarabine and CY followed by infusion of ex vivo T-cell-depleted grafts leads to excellent engraftment and absence of GVHD

We studied the outcome of individuals with aplastic anaemia (AA) who received reduced-intensity conditioning followed by the infusion of stem cell grafts that had been T-cell depleted ex vivo with alemtuzumab. Consecutive patients with AA who had an HLA-identical sibling received conditioning with fludarabine 30 mg/m(2) daily for 5 days followed by CY 60 mg/kg on 2 consecutive days. Cytokine-mobilized blood grafts were incubated ex vivo with alemtuzumab 'in the bag' and infused without washing. CYA was prescribed until day +90. Engraftment rate, GVHD, EFS and overall survival were studied. Fifteen patients received PBPC grafts. It was the second graft in one of the patients. Ten patients were male and their median age was 23.5 years. The toxicity of the conditioning was minimal. One patient received 1 x 10(7)/kg donor lymphocytes for rising chimerism. At a median of 1107 (294-1778) days, all of them survived with normal blood parameters. None of them developed acute or chronic GVHD. In patients with AA the combination of purine analogue and alkylator leads to rapid engraftment despite T-cell depletion of grafts. This strategy of reduced-intensity conditioning has low toxicity, does not compromise engraftment and seems effective for prevention of GVHD.

Autologous bone marrow transplantation in patients with subacute and chronic spinal cord injury

Stem cell transplants into spinal cord lesions may help to improve regeneration and spinal cord function. Clinical studies are necessary for transferring preclinical findings from animal experiments to humans. We investigated the transplantation of unmanipulated autologous bone marrow in patients with transversal spinal cord injury (SCI) with respect to safety, therapeutic time window, implantation strategy, method of administration, and functional improvement. We report data from 20 patients with complete SCI who received transplants 10 to 467 days postinjury. The follow-up examinations were done at 3, 6, and 12 months after implantation by two independent neurologists using standard neurological classification of SCI, including the ASIA protocol, the Frankel score, the recording of motor and somatosensory evoked potentials, and MRI evaluation of lesion size. We compared intra-arterial (via catheterization of a. vertebralis) versus intravenous administration of all mononuclear cells in groups of acute (10-30 days post-SCI, n=7) and chronic patients (2-17 months postinjury, n=13). Improvement in motor and/or sensory functions was observed within 3 months in 5 of 6 patients with intra-arterial application, in 5 of 7 acute, and in 1 of 13 chronic patients. Our case study shows that the implantation of autologous bone marrow cells appears to be safe, as there have been no complications following implantation to date (11 patients followed up for more than 2 years), but longer follow-ups are required to determine that implantation is definitively safe. Also, we cannot yet confirm that the observed beneficial effects were due to the cell therapy. However, the outcomes following transplantation in acute patients, and in one chronic patient who was in stable condition for several months prior to cell implantation, are promising. It is evident that transplantation within a therapeutic window of 3-4 weeks following injury will play an important role in any type of stem cell SCI treatment. Trials involving a larger population of patients and different cell types are needed before further conclusions can be drawn.

Current concepts in the pathophysiology and treatment of aplastic anemia

Aplastic anemia, an unusual hematologic disease, is the paradigm of the human bone marrow failure syndromes. Almost universally fatal just a few decades ago, aplastic anemia can now be cured or ameliorated by stem-cell transplantation or immunosuppressive drug therapy. The pathophysiology is immune mediated in most cases, with activated type 1 cytotoxic T cells implicated. The molecular basis of the aberrant immune response and deficiencies in hematopoietic cells is now being defined genetically; examples are telomere repair gene mutations in the target cells and dysregulated T-cell activation pathways. Immunosuppression with antithymocyte globulins and cyclosporine is effective at restoring blood-cell production in the majority of patients, but relapse and especially evolution of clonal hematologic diseases remain problematic. Allogeneic stem-cell transplant from histocompatible sibling donors is curative in the great majority of young patients with severe aplastic anemia; the major challenges are extending the benefits of transplantation to patients who are older or who lack family donors. Recent results with alternative sources of stem cells and a variety of conditioning regimens to achieve their engraftment have been promising, with survival in small pediatric case series rivaling conventional transplantation results.

Treatment of complete spinal cord injury patients by autologous bone marrow cell transplantation and administration of granulocyte-macrophage colony stimulating factor

Transplantation of bone marrow cells into the injured spinal cord has been found to improve neurologic functions in experimental animal studies. However, it is unclear whether bone marrow cells can similarly improve the neurologic functions of complete spinal cord injury (SCI) in human patients. To address this issue, we evaluated the therapeutic effects of autologous bone marrow cell transplantation (BMT) in conjunction with the administration of granulocyte macrophage-colony stimulating factor (GM-CSF) in six complete SCI patients. BMT in the injury site (1.1 x 10(6) cells/microL in a total of 1.8 mL) and subcutaneous GM-CSF administration were performed on five patients. One patient was treated with GM-CSF only. The follow-up periods were from 6 to 18 months, depending on the patients. Sensory improvements were noted immediately after the operations. Sensory recovery in the sacral segment was noted mainly 3 weeks to 7 months postoperatively. Significant motor improvements were noted 3 to 7 months postoperatively. Four patients showed neurologic improvements in their American Spiral Injury Association Impairment Scale (AIS) grades (from A to C). One patient improved to AIS grade B from A and the last patient remained in AIS grade A. No immediate worsening of neurologic symptoms was found. Side effects of GMCSF treatment such as a fever (>38 degrees C) and myalgia were noted. Serious complications increasing mortality and morbidity were not found. The follow-up study with magnetic resonance imaging 4-6 months after injury showed slight enhancement within the zone of BMT. Syrinx formation was not definitely found. BMT and GM-CSF administration represent a safe protocol to efficiently manage SCI patients, especially those with acute complete injury. To demonstrate the full therapeutic value of this protocol, long-term and more comprehensive case-control clinical studies are required.

Nonmyeloablative stem cell transplantation using lymphoablative rather than myeloablative conditioning in the prefludarabine era by ATG and limiting doses of cyclophosphamide

The feasibility of using lymphoablative rather than myeloablative conditioning for durable engraftment of allogeneic stem cells and subsequent cell therapy with donor lymphocytes was pioneered in the prefludarabine era in patients with resistant lymphoma and metastatic solid tumors. Between July 1995 and August 1996, 15 patients, five males and 10 females, median age 50 (range 20-57) years, were enrolled in a protocol that consisted of different doses of cyclophosphamide (Cy), 50 mg/kg/day for 1, 2, 3 or 4 consecutive days in parallel with a fixed dose of rabbit antithymocyte globulin (ATG) (Fresenius) 10 mg/kg/day for 4 consecutive days. All patients, except one treated with a single dose of Cy, achieved full tri-lineage engraftment and no late graft failure was observed. Only three patients suffered from grade III-IV graft-versus-host disease (GVHD). Three patients out of the 15 survived long term (follow-up >93 to >96 months). We concluded that lymphoablative conditioning with ATG and intermediate-to-high-dose Cy is well tolerated and can result in durable engraftment with acceptable GVHD in heavily pretreated patients with advanced malignancies. Hence, induction of tolerance to donor alloantigens by lymphoablative conditioning while avoiding myeloablative chemotherapy or radiation therapy may serve as a platform for subsequent cell therapy with donor lymphocytes.

Unrelated donor hematopoietic stem cell transplantation for patients with hematologic malignancies using a nonmyeloablative conditioning regimen of fludarabine, low-dose total body irradiation, and rabbit antithymocyte globulin

Hematopoietic stem cell chimerism can be established after low-dose conditioning regimens, although the risk of donor cell rejection increases for unrelated donor transplantations. We added pretransplantation rabbit antithymocyte globulin (6 mg/kg) to an established conditioning regimen of fludarabine (90 mg/m2) and single-fraction total body irradiation (200 cGy) followed by postgrafting immunosuppression with cyclosporine A and mycophenolate mofetil for 22 patients with hematologic malignancies. One patient rejected the graft and successfully underwent transplantation with cells from a second donor by using the same conditioning regimen. The actuarial probability of developing acute graft-versus-host disease grade II to IV before day 100 was 40%, although 9 of 14 patients who survived beyond 100 days developed chronic graft-versus-host disease. These data support a hypothesis that the addition of antithymocyte globulin decreases the risk of graft-versus-host and host-versus-graft reactions when combined with a nonmyeloablative conditioning regimen of fludarabine and total body irradiation.

Favorable effect on acute and chronic graft-versus-host disease with cyclophosphamide and in vivo anti-CD52 monoclonal antibodies for marrow transplantation from HLA-identical sibling donors for acquired aplastic anemia

Between August 1989 and November 2003, 33 patients at our center with acquired aplastic anemia underwent bone marrow transplantation (BMT) from HLA-identical sibling donors with cyclophosphamide and in vivo anti-CD52 monoclonal antibodies (MoAb) for conditioning. The median age at BMT was 17 years (range, 4-46 years). Before BMT, 58% were heavily transfused (>50 transfusions), and 42% had previously experienced treatment failure with antithymocyte globulin-based immunosuppressive therapy. Unmanipulated bone marrow was used as the source of stem cells in all patients except 1. Graft-versus-host disease (GVHD) prophylaxis was with cyclosporine alone in 19 (58%) patients; 14 received anti-CD52 MoAb in addition to cyclosporine. The conditioning regimen was well tolerated without significant acute toxicity. Graft failure was seen in 8 patients (primary, n = 4; secondary, n = 4). Of those whose grafts failed, 4 survived long-term (complete autologous recovery, n = 2; rescue with previously stored marrow, n = 1; second allograft, n = 1). The cumulative incidence of graft failure and grade II to IV acute and chronic GVHD was 24%, 14%, and 4%, respectively. None developed extensive chronic GVHD. With a median follow-up of 59 months, the 5-year survival was 81% (95% confidence interval, 68%-96%). No unexpected early or late infectious or noninfectious complications were observed. We conclude that the conditioning regimen containing cyclophosphamide and anti-CD52 MoAb is well tolerated and effective for acquired aplastic anemia with HLA-matched sibling donors. The favorable effect on the incidence and severity of GVHD is noteworthy in this study and warrants further investigation.

Radiotherapy-based conditioning is effective immunosuppression for patients undergoing transplantation with T-cell depleted stem cell grafts for severe aplasia

BACKGROUND

We studied the outcome of individuals with aplastic anemia conditioned with a radiation-containing regimen followed by an infusion of stem cell grafts that had been depleted of lymphocytes with CAMPATH-1H (antiCD52; humanised).

METHODS

The conditioning regime consisted of fractionated (f) TBI 8 Gy followed by f total nodal irradiation (TNI) 6 Gy. In addition, patients received CY 60 mg/kg on 2 consecutive days. Cytokine-mobilized peripheral blood grafts from HLA-identical siblings were T-cell depleted with CAMPATH-1H 'in the bag'. CsA was commenced on day -1 and continued until day +90.

RESULTS

Seventeen heavily transfused patients with aplastic anemia, median age 18 years (range 14-56 years), were studied. The median time from diagnosis to transplantation was 172 days (range 34-443 days). The median CD34(+) cell number infused was 3.47 x 10(6)/kg (range 1.03-18.4 x 10(6)/kg). All patients engrafted. Recovery was fast and patients reached 0.5 x 10(9)/L polymorphs by median day 11 (range 9-17 days). Toxicity from the conditioning included grade 4 hematologic toxicity in all patients. Another major toxicity was gastrointestinal mucosal damage, which exceeded grade 2 in two instances. One patient developed thrombotic thrombocytopenic purpura, which responded to substitution of CsA with tacrolimus and plasmapheresis. Another patient, who had normal blood counts, died of infection on day 241. Chimerism studies at 6 months post-transplantation confirmed the donor origin of hematopoiesis in all seven patients tested. None of the patients developed acute or chronic GvHD. There was no delayed graft failure and 94% of patients had survived disease free at a median of 1303.5 days (range 216-2615 days) from graft infusion.

DISCUSSION

In this cohort of multiply transfused patients, the radiation-containing schedules described in this study led to universal engraftment with limited toxicity despite T-cell depletion. No patient developed GvHD or late graft failure. Lower doses of radiation-containing conditioning should be explored further.

Bleeding complications after hematopoietic stem cell transplantation

Hemostatic disturbances are common in patients undergoing hematopoietic stem cell transplantation (HSCT), and have a significant impact on morbidity and mortality. Graft-versus-host disease (GvHD), in which the donor's T lymphocytes mount an immune response against the recipient's cells, is a life-threatening condition that correlates strongly with the incidence and severity of bleeding episodes, highlighting the complex interaction between the hemostatic and immunological systems. Patients with GvHD of the gut also exhibit a deficiency of factor XIII (FXIII), further increasing the hemorrhagic risk. Among other risk factors for bleeding complications is use of the purified polyclonal immunoglobulin G (IgG), antithymocyte globulin (ATG). Although frequently used in preparative conditioning regimens, ATG may contribute to leukopenia, platelet reduction, and signs of disseminated intravascular coagulation (DIC). This paper will examine the cause and incidence of bleeding complications in patients undergoing HSCT, the potential contribution of GvHD and ATG to such bleeds, and the close interaction between the hemostatic and immune systems. The role of recombinant FVIIa as a hemostatic agent for the treatment of HSCT-associated hemorrhage will be briefly explored.

Ex Vivo Immunotherapy for Patients with Benzene-Induced Aplastic Anemia

Aplastic anemia is a bone marrow failure disorder characterized by pancytopenia and a hypocellular marrow. Benzene is one of the etiologic agents capable of inducing the disease. With modest to severe aplastic anemia, one previously untreated patient and 13 patients who had failed immunosuppressive therapy were studied. Peripheral blood mononuclear cells from patients were expanded in vitro with a combination of cytokines and a calcium-mobilizing agents for 2 days, and the activated cells were infused intravenously once a week. In some cases, we used allogenic leukocytes instead of autologous cultured lymphocytes. After 6-35 weeks of the treatment, all patients had multilineage responses to this therapy and achieved complete disease remission, defined as normal blood count, independence from transfusion, and normal bone marrow histology. The therapy was safe and well tolerated with minimal side effects. The cultured cells produced interleukin-1 and induced immune responses in vivo. Serum interleukin-2 and interferon- gamma were detected following cell infusion. Finally, patients had sustained responses to the therapy and no relapse was found up to 18 months after cellular therapy.