Reduced toxicity and prompt engraftment after minimal conditioning of a patient with Fanconi anemia undergoing hematopoietic stem cell transplantation from an HLA-matched unrelated donor

MHC-matched induced pluripotent stem cells can attenuate cellular and humoral immune responses but are still susceptible to innate immunity in pigs

Recent studies have revealed negligible immunogenicity of induced pluripotent stem (iPS) cells in syngeneic mice and in autologous monkeys. Therefore, human iPS cells would not elicit immune responses in the autologous setting. However, given that human leukocyte antigen (HLA)-matched allogeneic iPS cells would likely be used for medical applications, a more faithful model system is needed to reflect HLA-matched allogeneic settings. Here we examined whether iPS cells induce immune responses in the swine leukocyte antigen (SLA)-matched setting. iPS cells were generated from the SLA-defined C1 strain of Clawn miniature swine, which were confirmed to develop teratomas in mice, and transplanted into the testes (n = 4) and ovary (n = 1) of C1 pigs. No teratomas were found in pigs on 47 to 125 days after transplantation. A Mixed lymphocyte reaction revealed that T-cell responses to the transplanted MHC-matched (C1) iPS cells were significantly lower compared to allogeneic cells. The humoral immune responses were also attenuated in the C1-to-C1 setting. More importantly, even MHC-matched iPS cells were susceptible to innate immunity, NK cells and serum complement. iPS cells lacked the expression of SLA class I and sialic acids. The in vitro cytotoxic assay showed that C1 iPS cells were targeted by NK cells and serum complement of C1. In vivo, the C1 iPS cells developed larger teratomas in NK-deficient NOG (T-B-NK-) mice (n = 10) than in NK-competent NOD/SCID (T-B-NK+) mice (n = 8) (p<0.01). In addition, C1 iPS cell failed to form teratomas after incubation with the porcine complement-active serum. Taken together, MHC-matched iPS cells can attenuate cellular and humoral immune responses, but still susceptible to innate immunity in pigs.

DNA damage responses and oxidative stress in dyskeratosis congenita

Dyskeratosis congenita (DC) is an inherited multisystem disorder of premature aging, cancer predisposition, and bone marrow failure caused by selective exhaustion of highly proliferative cell pools. DC patients also have a poor tolerance to chemo/radiotherapy and bone marrow transplantation. Although critically shortened telomeres and defective telomere maintenance contribute to DC pathology, other mechanisms likely exist. We investigate the link between telomere dysfunction and oxidative and DNA damage response pathways and assess the effects of antioxidants. In vitro studies employed T lymphocytes from DC subjects with a hTERC mutation and age-matched controls. Cells were treated with cytotoxic agents, including Paclitaxel, Etoposide, or ionizing radiation. Apoptosis and reactive oxygen species (ROS) were assessed by flow cytometry, and Western blotting was used to measure expression of DNA damage response (DDR) proteins, including total p53, p53S15, and p21(WAF). N-acetyl-cysteine (NAC), an antioxidant, was used to modulate cell growth and ROS. In stimulated culture, DC lymphocytes displayed a stressed phenotype, characterized by elevated levels of ROS, DDR and apoptotic markers as well as a proliferative defect that was more pronounced after exposure to cytotoxic agents. NAC partially ameliorated the growth disadvantage of DC cells and decreased radiation-induced apoptosis and oxidative stress. These findings suggest that oxidative stress may play a role in the pathogenesis of DC and that pharmacologic intervention to correct this pro-oxidant imbalance may prove useful in the clinical setting, potentially alleviating untoward toxicities associated with current cytotoxic treatments.

Results of unrelated cord blood transplant in fanconi anemia patients: risk factor analysis for engraftment and survival

We retrospectively analyzed results of unrelated cord blood transplantation (UCBT) in 93 Fanconi anemia (FA) patients. Median age at transplantation was 8.6 years (1-45). The units transplanted were HLA-A, -B, or -DRB1 identical in 12 cases, 1 HLA mismatch in 35 cases, and 2 or 3 HLA differences in 45 cases. The median number of nucleated cells (NC) and CD34+ cells infused of recipient weight was 4.9x10(7)/kg and 1.9x10(5)/kg, respectively. Participating centers selected the preparative regimen of their choice, in 57 patients (61%), it included Fludarabine. Graft-versus-host disease (GVHD) prophylaxis consisted mostly of cyclosporine with prednisone. Cumulative incidence (CI) of neutrophil recovery was 60+/-5% at day +60. In multivariate analysis, Fludarabine containing regimen and NC infused>or=4.9x10(7)/kg were associated with higher probability of recovery. CI of grade II-IV acute and of chronic GVHD (aGVHD, cGVHD) was 32%+/-5% and 16%+/-4%, respectively. Overall survival (OS) was 40%+/-5%. In multivariate analysis, factors associated with favorable outcome were use of Fludarabine in the conditioning regimen, number of NC infused>or=4.9x10(7)/kg, and negative cytomegalovirus (CMV) serology in the recipient. In conclusion, factors easily modifiable such as donor selection and a Fludarabine-containing regimen can considerably improve survival in FA patients given a UCBT. These data are the basis for designing prospective protocols.

Fludarabine-Based Reduced Intensity Conditioning for Stem Cell Transplantation of Fanconi Anemia Patients from Fully Matched Related and Unrelated Donors

Reduced intensity conditioning has been suggested as a desirable therapeutic modality for the treatment of patients with malignant and nonmalignant indications, but it seems particularly attractive for patients with Fanconi anemia due to their increased sensitivity to chemoradiotherapy. Between November 1996 and September 2003, 7 patients (1 male and 6 female; age range, 3-31 years; median age, 9.5) were conditioned with a fludarabine-based protocol for stem cell transplantation without radiation. In vivo T-cell depletion was accomplished with anti-thymocytic globulin or Campath-1H (alemtuzumab). Graft-versus-host disease prophylaxis consisted of low-dose cyclosporine alone. Eight transplantations were carried out for 7 patients using bone marrow, peripheral blood, and/or cord blood as sources of stem cells. All patients received transplants from HLA-A, -B, -C, and -DR matched donors, 5 from family members and 2 from matched unrelated donors. One patient did not engraft her first matched unrelated donor and underwent a second transplantation from another matched unrelated donor, after which she engrafted well. All 7 patients are alive and well, fully reconstituted with donor cells, and with 100% performance status. In conclusion, fludarabine-based preparative protocols are well tolerated, facilitate rapid engraftment with minimal toxicity, and should be considered an essential component of choice for patients with Fanconi anemia.

Low-dose cyclophosphamide conditioning for haematopoietic cell transplantation from HLA-matched related donors in patients with Fanconi anaemia

Allogeneic haematopoietic cell transplantation (HCT) is effective therapy for Fanconi anaemia (FA). FA patients do not tolerate conditioning with 200 mg/kg of cyclophosphamide (Cy), typically used in aplastic anaemia. We previously published results of studies in which Cy doses were gradually reduced from 200 to 100 mg/kg. Here we update results of the initial studies and report data on 30 new patients conditioned with Cy either at 80 mg/kg (n = 7) or at 60 mg/kg (n = 23), given over 4 days before HCT from human leucocyte antigen-matched related donors. Methotrexate and cyclosporine were given for graft-versus-host disease (GVHD) prophylaxis. All seven patients given Cy at 80 mg/kg and 21 of 23 given Cy at 60 mg/kg had sustained engraftment, while two patients, both with clonal cytogenetics abnormalities, experienced graft failure. Grades 2-3 acute GVHD rates were 57% and 14% for patients given the higher and lower Cy doses, respectively (P = 0.001). Four patients given Cy at 80 mg/kg and 22 given Cy at 60 mg/kg were alive at a median of 47 (44-58) months and 16 (3-52) months, respectively. Cy at 60 mg/kg has acceptable toxicities, low rates of GVHD, and is sufficient for engraftment of related grafts in most FA patients.

Fludarabine-based conditioning for allogeneic stem cell transplantation for multiply transfused patients with Fanconi's anemia

A fludarabine-based protocol (fludarabine (25 mg/m(2)/day x 6 days), cyclophosphamide (10 mg/kg/day x 2 days) and ATG (ATGAM 10 mg/kg/day x 4 days)) was used in four multiply transfused Fanconi's anemia (FA) patients aged 5-15 years to reduce rejection during allogeneic bone marrow transplantation (BMT). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mini methotrexate. The graft source was G-CSF-stimulated bone marrow or peripheral blood stem cells (PBSC) in two patients each. All patients engrafted with median time to ANC>500/mm(3) being 14 days (range: 12-17) and unsupported platelet count >20 ,000/mm(3) being 13 days (range: 11-18). One patient had secondary graft rejection on day 56 and expired on day 69 due to fungal pneumonia. One patient who developed acute myeloid leukemia on day 56 underwent successful induction with cytosine and daunorubicin followed by peripheral blood stem cell (PBSC) rescue on day 70 and is presently in remission with complete donor chimerism and grade I GVHD. At a median follow-up of 13 months (range: 4-21), three patients (75%) are well with complete donor chimerism. Addition of fludarabine to the conditioning regimen for BMT in FA can provide additional immunosuppression for engraftment without increasing toxicity.

Fludarabine, low-dose busulfan and antithymocyte globulin as conditioning for Fanconi anemia patients receiving bone marrow transplantation from HLA-compatible related donors

Allogeneic hematopoietic stem cell transplantation (SCT) from unaffected donors remains the only modality for the correction of hematological abnormalities in Fanconi anemia (FA) patients. We performed four HLA-matched related donor SCT using a novel irradiation and cyclophosphamide-free conditioning regimen. The protocol included fludarabine 150 mg/m(2), busulfan 4 mg/kg, and antithymocyte globulin 90 mg/kg. Graft-versus-host disease (GVHD) prophylaxis was cyclosporin A, MTX, and daclizumab. The engraftment and occurrence of full stable donor hemopoiesis was rapid in all cases with minimal short-term toxic complications. There were no infections or febrile episodes during the inpatient phase. Three patients developed acute GVHD grade I-II involving gut and skin and one patient progressed to extensive chronic GVHD. The preparative conditioning regimen is safe and associated with low organ toxicity and effective immunosupression for the stable engraftment in FA patients undergoing SCT with matched related donors.

Non-myeloablative allogeneic transplantation -- state-of-the-art

Work by several groups of investigators has brought about changes in the way hematopoietic cell allografts are being done to treat patients with hematologic diseases. Less intensive conditioning regimens have been introduced, and in the case of patients with hematologic malignancies, the burden of eradicating malignant cells has shifted from high-dose chemoradiation treatment toward using the hematopoietic cell donor's T lymphocytes for that purpose by invoking allogeneic graft-versus-tumor effects. While the majority of the transplant regimens used in these efforts are still fairly intense and toxic, a radical departure from conventional transplantation focuses on the almost exclusive use of immunosuppressive agents with little toxicity to establish the allografts. The success of the procedure for patients with hematologic malignancies rests on replacing the host's hematopoietic cells by the allograft. For non-malignant diseases, the procedure can be used to establish a stable state of mixed donor/host hematopoietic chimerism, which, in itself, may be sufficient to cure disease manifestations.

Effective graft-versus-leukaemia effect after allogeneic stem cell transplantation using reduced-intensity preparative regimens in Fanconi anaemia patients with myelodysplastic syndrome or acute myeloid leukaemia

Allogeneic transplantation is the only curative treatment for Fanconi anaemia (FA) patients who develop myeloid malignancies. Dose-intensive preparative regimens, to decrease disease recurrence, lead to unacceptable transplant-related toxicity in FA. We report the outcome of three FA patients with such malignancies who underwent transplantation with reduced-intensity preparative regimens. This approach was well tolerated, even as second transplantations, and resulted in complete leukaemic remissions. However, the graft-versus-leukaemia effect was associated with fatal graft-versus-host disease. Even after transplantation, myeloid malignancies remain associated with a poor outcome in FA, and this argues in favour of early intervention when suitable donors are available.