Fludarabine-based protocol for human umbilical cord blood transplantation in children with Fanconi anemia

Outcome of hematopoietic stem cell transplantation (HCT) from HLA-matched related donor for Fanconi anemia (FA) in adolescents and adults: a retrospective study by Eastern Mediterranean Blood and Marrow Transplantation Group (EMBMT)

Hematopoietic Stem Cell Transplantation (HSCT) is the only potentially curative treatment option for the hematologic complications that occur in patients with Fanconi anemia (FA). In this study, we present a retrospective multicenter analysis from the Eastern Mediterranean Blood and Marrow Transplantation Group (EMBMT) of matched related donor HSCT for FA in adolescents and adults transplanted between 1988 and 2015. Forty-five patients received HSCT with a median age at transplant of 18 years, the interquartile range (IQR) (15-23.5); 25 (55.6%) patients were females and 20 (44.4%) were males. Conditioning regimen was fludarabine-based in 29 (64.4%) patients, irradiation-based in five (11.1%) patients, and the remaining patients received other combinations. Indication for HSCT was bone marrow failure in 39 (86.7%) and myelodysplastic syndrome in six (13.3%) patients. Stem cell source was bone marrow in 22 (48.9%), peripheral blood in 20 (44.4%), umbilical cord blood in one (2.2%), and combination of bone marrow and cord blood in two (4.4%) patients. Twenty-seven (60%) patients engrafted and five (11.1%) had primary engraftment failure. The median time to neutrophil engraftment was 14 days (range 10-21 days); median time for platelet engraftment was 17 days (10-33 days). The probability of developing grade II-IV acute GVHD for all patients was 7.0% and chronic GVHD 36.6%. No new malignancies were reported. The OS probability was 53.6% (95% CI, 38.3-68.9%) with a median follow-up of 13 months (95% CI, 1-240). Our HLA-matched related HSCT results in AYA patients with FA compare favorably with other reported international registry data.

Recent advances in understanding hematopoiesis in Fanconi Anemia

Fanconi anemia is an inherited disease characterized by genomic instability, hypersensitivity to DNA cross-linking agents, bone marrow failure, short stature, skeletal abnormalities, and a high relative risk of myeloid leukemia and epithelial malignancies. The 21 Fanconi anemia genes encode proteins involved in multiple nuclear biochemical pathways that effect DNA interstrand crosslink repair. In the past, bone marrow failure was attributed solely to the failure of stem cells to repair DNA. Recently, non-canonical functions of many of the Fanconi anemia proteins have been described, including modulating responses to oxidative stress, viral infection, and inflammation as well as facilitating mitophagic responses and enhancing signals that promote stem cell function and survival. Some of these functions take place in non-nuclear sites and do not depend on the DNA damage response functions of the proteins. Dysfunctions of the canonical and non-canonical pathways that drive stem cell exhaustion and neoplastic clonal selection are reviewed, and the potential therapeutic importance of fully investigating the scope and interdependences of the canonical and non-canonical pathways is emphasized.

Comparable Outcomes after HLA-Matched Sibling and Alternative Donor Hematopoietic Cell Transplantation for Children with Fanconi Anemia and Severe Aplastic Anemia

Fanconi anemia (FA)-associated severe aplastic anemia (SAA) requires allogeneic hematopoietic cell transplantation (HCT) for cure. With the evolution of conditioning regimens over time, outcomes of alternative donor HCT (AD-HCT) have improved dramatically. We compared outcomes of HLA-matched sibling donor HCT (MSD-HCT; n = 17) and AD-HCT (n = 57) performed for FA-associated SAA at a single institution between 2001 and 2016. Overall survival at 5 years was 94% for MSD-HCT versus 86% for AD-HCT, neutrophil engraftment was 100% versus 95%, platelet recovery was 100% versus 89%, grade II-IV acute graft-versus-host disease (GVHD) was 6% versus 12%, grade III-IV acute GVHD was 6% versus 4%, and chronic GVHD was 0 versus 7%, with no statistically significant differences by type of transplant. The use of UCB was associated with decreased rates of neutrophil recovery in AD-HCT and platelet recovery in both MSD-HCT and AD-HCT. A trend toward a higher serious infection density before day +100 post-HCT was observed in AD-HCT compared with MSD-HCT (P = .02). These data demonstrate that AD-HCT should be considered at the same time as MSD-HCT for patients with FA-associated SAA.

Hematopoietic cell transplantation in Fanconi anemia: current evidence, challenges and recommendations

INTRODUCTION

Hematopoietic cell transplantation for Fanconi Anemia (FA) has improved dramatically over the past 40 years. With an enhanced understanding of the intrinsic DNA-repair defect and pathophysiology of hematopoietic failure and leukemogenesis, sequential changes to conditioning and graft engineering have significantly improved the expectation of survival after allogeneic hematopoietic cell transplantation (alloHCT) with incidence of graft failure decreased from 35% to <10% and acute graft-versus-host disease (GVHD) from >40% to <10%. Today, five-year overall survival exceeds 90% in younger FA patients with bone marrow failure but remains about 50% in those with hematologic malignancy. Areas covered: We review the evolution of alloHCT contributing to decreased rates of transplant related complications; highlight current challenges including poorer outcomes in cases of clonal hematologic disorders, alloHCT impact on endocrine function and intrinsic FA risk of epithelial malignancies; and describe investigational therapies for prevention and treatment of the hematologic manifestations of FA. Expert commentary: Current methods allow for excellent survival following alloHCT for FA associated BMF irrespective of donor hematopoietic cell source. Alternative curative approaches, such as gene therapy, are being explored to eliminate the risks of GVHD and minimize therapy-related adverse effects.

Four decades of stem cell transplantation for Fanconi anaemia in the Netherlands

This article presents the haematopoietic stem cell transplantation (SCT) results of the complete Dutch Fanconi anaemia (FA) patient cohort. Sixty-eight Dutch FA patients have been transplanted since 1972. In total, 63 (93%) patients engrafted, 54 after first SCT and 9 after second SCT. Fludarabine (FLU)-based conditioning was associated with decreased graft failure (odds ratio 0·21, P = 0·01), decreased early mortality (hazard ratio 0·25, P = 0·01) and improved 5-year overall survival (FLU 87·8% [standard error (SE) 5·1%] versus non-FLU 59·3% [SE 9·5%], P = 0·01). Late mortality was mainly caused by squamous cell carcinoma. Twenty-two patients were treated with the current Dutch FA conditioning regimen (FLU 150 mg/m(2) and cyclophosphamide 30 mg/kg ± anti-thymocyte globulin - no irradiation). Stem cell donors were matched related (n = 8) or alternative donors (n = 14). Stable engraftment after first SCT was achieved in 19 (86%) patients. At a median follow-up of 3·9 years 20 (91%) patients are alive. Our study provides a unique overview of a nation-wide SCT cohort illustrating the major improvements in treatment regimen and patient outcome in recent years. It shows that a non-irradiation and busulfan-free conditioning regimen can be used successfully, also in alternative donor SCT. Furthermore, it underlines the importance of late cancer screening and comprehensive care for this complex disorder.

Improved Outcomes of Hematopoietic Stem Cell Transplantation in Patients With Infantile Malignant Osteopetrosis Using Fludarabine-Based Conditioning

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for infantile malignant osteopetrosis (IMO), but is associated with a high incidence of adverse outcomes. In this study, we present our experience with HSCT for IMO patients comparing different types of conditioning regimens.

METHODS

Thirty-eight patients with IMO (aged from 1 month to 6 years, median 0.66 years) who underwent allogeneic HSCT from 1983 in our hospital were included in this retrospective study. Fludarabine-based conditioning regimens were used in 26 patients and 12 patients were transplanted using other conditioning regimens.

RESULTS

The overall survival after conditioning with fludarabine was 96% (25/26) versus 58% (7/12) for the alternative regimens (P = 0.004), with significantly fewer adverse effects including hypercalcemia and veno-occlusive disease of liver. All patients who survive are clinically well.

CONCLUSIONS

We conclude that fludarabine-based conditioning regimens are safe and effective in patients with IMO, improving morbidity and mortality related to HSCT.

Successful T-cell-depleted haploidentical hematopoietic stem cell transplantation in a child with dyskeratosis congenita after a fludarabine-based conditioning regimen

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only cure for marrow failure associated with dyskeratosis congenita (DC). Data on transplants from alternative donors are limited. We describe a boy with DC and severe aplastic anemia who underwent haploidentical T-cell depleted HSCT using a reduced-intensity conditioning regimen. He underwent engraftment without toxicity or GVHD. His posttransplant course was complicated by EBV reactivation, treated with rituximab and EBV-specific T lymphocytes. After 26 months, he is in complete chimerism, with normal blood count and no sign of GVHD or pulmonary dysfunction. To the best of our knowledge, this is the first report of DC successfully treated with allogeneic HSCT from a haploidentical family donor.

Outcomes of mismatched and unrelated donor hematopoietic stem cell transplantation in Fanconi anemia conditioned with chemotherapy only

Fanconi anemia (FA) is a genomic instability syndrome associated with bone marrow failure, myelodysplastic syndrome (MDS), and/or acute myeloid leukemia (AML) requiring hematopoietic stem cell transplantation (HSCT) to restore normal hematopoiesis. Although low-intensity fludarabine-based preparative regimens without radiation confer excellent outcomes in FA HSCTs with HLA-matched sibling donors, outcomes for FA patients with alternative donors are less encouraging, albeit improving. We present our experience with 17 FA patients who completed mismatched related or unrelated donor HSCT using a non-radiation fludarabine-based preparative regimen at Charité University Medicine Berlin. All patients engrafted; however, one patient had unstable chimerism in the setting of multi-viral infections that necessitated a stem cell boost to revert to full donor chimerism. Forty-seven percent of patients developed grade I acute graft-verus-host disease (aGVHD). No grade II-IV aGVHD or chronic graft-versus-host disease of any severity occurred. At a median follow-up of 30 months, 88 % of patients are alive with normal hematopoiesis. Two patients died of infections 4 months post-transplantation. These results demonstrate that short-term outcomes for FA patients with mismatched and unrelated donor HSCTs can be excellent using chemotherapy only conditioning. Viral reactivation, however, was a major treatment-related complication.

Lentiviral Based Gene Transduction and Promoter Studies in Human Hematopoietic Stem Cells (hHSCs)

Human hematopoietic stem cells (hHSCs) have enormous potential for clinical use in cell-based therapies, especially as a gene delivery system. Moreover, lentiviral transduction in stem cells is very often associated with low transduction efficiency and low levels of foreign gene expression. Therefore, it is important to analyze vector and promoter systems that can generate robust foreign gene expression in these cells. In this study, we evaluated and compared the ability of different commercially available promoters to drive the expression of exogenous reporter genes in hHSCs and evaluated the effect of different doses of stem cell growth factors on the expression of transgenes. We used lentivirus based vector system carrying the following promoters: 1) Human cytomegalovirus (CMV) promoter, 2) Simian virus 40 (SV40) promoter, 3) mammalian Ubiquitin C (UBC) promoter and 4) cellular polypeptide chain elongation factor 1 alpha (EF1) promoter. EF1 and CMV promoters robustly drove the expression of green fluorescence protein (GFP) reporter gene, while SV40 and UBC promoters induced very low level of GFP expression. Lentivectors containing EF1 and CMV promoters showed high-level stable GFP expression in human cord blood stem cells for 6 weeks period after post transduction. CD133+ hHSCs stimulated with higher concentration of growth factors exhibited enhancement of transduction rate. Cord blood derived CD133+ hHSCs could be effectively transduced with lentivectors under CMV or EF-1 promoters for the expression of foreign gene

Cellular therapy for fanconi anemia: the past, present, and future

Allogeneic hematopoietic cell transplantation (HCT) remains the only proven curative therapy for the hematologic manifestation of Fanconi anemia (FA). Over the past 2 decades, major advances have been made such that transplant outcomes have markedly improved. With the development of in vitro fertilization and preimplantation genetic diagnosis, HLA-matched sibling donor umbilical blood transplantation may be an option for more patients with FA. Recently, the use of pluripotent stem cells has been explored as a novel approach to model the hematopoietic developmental defects in FA, and to provide a potential source of autologous stem cells that can be genetically manipulated and used to generate corrected hematopoietic progenitors.

Transplant outcomes in bone marrow failure syndromes and hemoglobinopathies

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only potential cure for most bone marrow (BM) failure syndromes and hemoglobinopathies. Over the past decade, umbilical cord blood (UCB) has been used more frequently as a stem cell source in patients who lack a suitable BM donor. Although graft failure remains a significant problem, UCB transplantation (UCBT) using the optimal conditioning regimen can be a salvage treatment for patients without a suitable BM donor and warrants evaluation in further prospective studies.

Haematopoeitic cell transplantation for Fanconi anaemia - when and how?

Allogeneic haematopoietic cell transplantation (HCT) remains the only treatment that can correct the haematological manifestations in patients with Fanconi anaemia. Over the last two decades, sequential changes to the approach to HCT have resulted in reduced regimen-related toxicity, superior engraftment and less graft-versus-host disease (GVHD), resulting in improved survival. The two pivotal changes that most influenced these improvements were the addition of fludarabine to the preparative regimen to augment engraftment, and the use of T cell depletion to reduce GVHD. With these improved HCT outcomes, indications for HCT are quite consistent regardless of donor source. Emphasis is now being placed on developing HCT regimens that will improve quality of life by reducing late effects, particularly the risk of malignancy, sterility and endocrinopathies. This paper will review the unique challenges of HCT in FA patients, with particular emphasis on the timing and approach to HCT.

Bone marrow transplantation for inherited bone marrow failure syndromes

The inherited bone marrow failure (BMF) syndromes are characterized by impaired hematopoiesis and cancer predisposition. Most inherited BMF syndromes are also associated with a range of congenital anomalies. Progress in improving the outcomes for children with inherited BMF syndromes has been limited by the rarity of these disorders, as well as disease-specific genetic, molecular, cellular, and clinical characteristics that increase the risks of complications associated with hematopoietic stem cell transplantation (HSCT). As a result, the ability to develop innovative transplant approaches to circumvent these problems has been limited. Recent progress has been made, as best evidenced in studies adding fludarabine to the preparative regimen for children undergoing unrelated donor HSCT for Fanconi anemia. The rarity of these diseases coupled with the far more likely incremental improvements that will result from ongoing research will require prospective international clinical trials to improve the outcome for these children.

Allogeneic hematopoietic stem cell transplantation of patients with FA and high risk features using fludarabine without radiation

Several factors unique to Fanconi anemia (FA) limit the success of allogeneic hematopoietic stem cell transplantation (HSCT) in this population. In this report, we describe a multi-center pilot study of five consecutive FA patients with high-risk features for transplant prepared with fludarabine, without radiation. Four patients engrafted quickly, experienced minimal toxicity and are well at 43-65 months post-transplant. One patient had a C-mismatched unrelated donor transplant and had unsustained engraftment. This fludarabine based regimen without radiation was safe and effective for four high-risk patients, suggesting that eliminating radiation should be further studied as an approach to HSCT in children with FA.

Related donor hematopoietic stem cell transplantation for Fanconi anemia without radiation: a single center experience in Turkey

Eight children with FA underwent allogeneic HSCT without using irradiation for the conditioning regimen. Patients received two different conditioning regimens: first two patients received BU 1.5 mg/kg/day for four days and CY 10 mg/kg/day for four days and the other regimen was: Flu 30 mg/m(2)/day for five days, CY 10 mg/kg/day for two days, and ATG-Fresenius 9-10 mg/kg/day for four days. GVHD prophylaxis consisted of CsA + MTX for the first two patients and only CsA for the others. All patients received HLA-identical stem cells from related donors. Primary engraftment was demonstrated in all patients. No patient developed acute GVHD and one patient had chronic GVHD. Only one patient who received BU based regimen died because of VOD. Overall, seven patients (87.5%) are alive with stable full donor chimerism at a median follow-up time of 2.5 yr (range: 1.7-8.9 yr). None of the patients developed secondary malignancy. Based on our data, we conclude that Flu-based, non-irradiation conditioning regimen was safe with low organ toxicity and stable engraftment in FA patients undergoing HSCT from matched related donors.

CD-34 selected hematopoetic stem cell transplantation from HLA identical family members for fanconi anemia

Hematopoetic stem cell transplantation, even from an HLA 6/6 identical family member is associated with an increased frequency of complication in fanconi anemia (FA). The increased susceptibility for chromosomal breaks has been suggested as a contributory factor for increased risk of toxicity, graft versus host disease (GVHD) and increased incidence of post-transplant solid tumors. Therefore, non-irradiation based preparative regimens usually containing fludarabine and T-cell depletion of HLA geno-identical bone marrow cells have increasingly been used in patients with FA. Here, we report three children with FA who underwent CD-34 selected HSCT from HLA-identical family donors with reduced intensity fludarabine-based regimen.

Fludarabine-based disease-specific conditioning or conventional myeloablative conditioning in hematopoietic stem cell transplantation for treatment of non-malignant diseases

Fludarabine-based conditioning (FBC) was given to 24 patients and conventional myeloablative conditioning (MC) to 33 patients, most children, before hematopoietic stem cell transplantation (HSCT) for non-malignant diseases. The donors were human leukocyte antigen (HLA)-A, -B, -DRbeta1-identical related (33%) or unrelated (67%). In the FBC group, two grafts failed versus three in the MC group; all were successfully regrafted. Fever was more common in the MC patients (P=0.003). Bacteremia occurred in 25% of the FBC group and 50% in the MC group (P=0.1). In the FBC group, platelet engraftment was faster and transfusions were fewer (P<0.05). Mucositis and renal function were similar in the two groups. The MC group had higher maximum bilirubin (P=0.03) and less often normal spirometry (P=0.04) after HSCT. A 7-year-old girl in the MC group had permanent alopecia. No patients had severe acute graft-versus-host disease (GVHD). Chronic GVHD was rare. Complete donor CD3+ chimerism was more common in the MC group (P=0.01), but CD33+ engraftment was better with FBS (P=0.03). Treatment-related mortality was 4 and 15%, and 5-year survival was 89 and 85% in the FBC and MC groups. Although survival was similar, FBC is a promising alternative to MC in non-malignant disorders.

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.

Successful engraftment without radiation after fludarabine-based regimen in Fanconi anemia patients undergoing genotypically identical donor hematopoietic cell transplantation

BACKGROUND

To potentially reduce late effects of malignancy, chronic graft-versus-host disease (GVHD), endocrinopathy, and infertility in patients with Fanconi anemia (FA) undergoing HLA-matched related donor hematopoietic cell transplantation (HCT), we developed a regimen using fludarabine (FLU), cyclophosphamide (CY), and anti-thymocyte globulin (ATG) followed by infusion of T-cell depleted (TCD) bone marrow (BM) or unmanipulated umbilical cord blood (UCB). GVHD prophylaxis consisted of cyclosporine and short course methylprednisolone.

PROCEDURE

Between April 2000 and June 2003, 11 patients (10 aplastic anemia (AA), 1 myelodysplastic syndrome (MDS)) underwent HCT using this regimen. Stem cell sources were BM and UCB in eight and three patients, respectively.

RESULTS

All patients demonstrated primary engraftment. Median days to neutrophil and platelet engraftment were 11 days (range 9-21) and 38 days (range 19-381), respectively. No patient developed GVHD after primary HCT. The patient with MDS relapsed with AML and a maternal donor recipient experienced secondary graft failure. For the nine FA patients with AA who underwent HLA-identical sibling donor HCT, the Kaplan-Meier estimates of overall survival and event-free survival (EFS) at 2 years are 100% and 82%, respectively, at a median follow-up of 2.9 years (range 1.9-4.8).

CONCLUSIONS

In summary, a FLU-based, non-irradiation approach is effective for FA patients with AA undergoing HLA-identical sibling donor HCT.

Successful HSCT using nonradiotherapy-based conditioning regimens and alternative donors in patients with Fanconi anaemia--experience in a single UK centre

Seven children with Fanconi anaemia (FA) (five female, two male), who had not undergone transformation, received nine haemopoietic stem cell transplantation (HSCT) between 2000 and 2004. Conditioning regimen was: fludarabine 25-30 mg/m2/day for 5 days, antilymphocyte globulin 12.5 mg/kg/day for 3 days and cyclophosphamide 5-7.5 mg/kg/day for 4 days. Radiation was not used. One male patient who had multiple HSCT and one female who was retransplanted, received slightly different conditioning regimens. Four patients received fully matched unrelated umbilical cord blood (UCB), two matched unrelated peripheral blood stem cell (PBSC) grafts, and three haploidentical T-cell-depleted (TCD) PBSC grafts. None of the patients had any significant conditioning-related toxicity or severe infections. All engrafted within 2-3 weeks. One patient rejected her first HSCT after 10 weeks and had a second successful transplant from the same donor. One male patient rejected his TCD haploidentical HSCT from his mother, and subsequently had a successful fully matched unrelated UCB transplant. Rejection rate was 22%. Acute and chronic graft-versus-host disease (GVHD) was seen in 77 and 22% patients. In all, 57% patients developed autoimmune complications, all of which have resolved. All patients are well with stable or full donor chimerism after a median follow-up of 37 months (range 13-54).

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.

Hematopoietic cell transplantation for congenital bone marrow failure

PURPOSE OF REVIEW

Congenital bone marrow failure is rare and multifactorial. This review focuses on the outcome after allogeneic hematopoietic cell transplantation for the treatment of these disorders, with particular emphasis on recent discoveries and the challenges.

RECENT FINDINGS

In the treatment of congenital bone marrow failure disorders, the goals are to eliminate or reduce early and late toxicities and the risk of graft-versus-host disease. Novel nonmyeloablative fludarabine-based preparative regimens have demonstrated low risks of toxicity and acceptable engraftment rates for several congenital bone marrow failure disorders. Although there seems to be less early toxicity, longer follow-up is needed to determine late effects, especially the development of malignancy. T cell depletion of the bone marrow or peripheral blood, or the use of umbilical cord blood, has decreased the risk of graft-versus-host disease. Together, reduced toxicity and low rates of graft-versus-host disease have at least minimized the morbidity early after transplantation, with promising early survival.

SUMMARY

With marked improvement in rates of survival after allogeneic hematopoietic cell transplantation for selected congenital bone marrow failure disorders, emphasis is now being placed on improving quality of life and reducing late effects. Multicenter collaborative trials will determine the best treatment for these rare disorders.

Umbilical cord blood transplantation – how, when and for whom?

In recent years, umbilical cord blood (UCB) has emerged as a feasible alternative source of hematopoietic progenitors (CD34+) for allogeneic stem cell transplantation, mainly in patients who lack HLA-matched marrow donors. Since the first case reported in 1998, more than 3500 patients have received UCB transplants for a variety of malignant and non-malignant diseases. The vast majority of recipients were children with an average weight of 20 kg; however, more than 500 UCB transplantations (UCBTs) have already been performed in adults. The "naive" nature of UCB lymphocytes also permits the use of HLA-mismatched grafts at 1-2 loci without higher risk for severe graft versus host disease (GvHD) relative to bone marrow transplantation (BMT) from a full matched unrelated donor. Furthermore, UCB is rich in primitive CD16(-)CD56++ NK cells, which possess impressive proliferative and cytotoxic capacities and can be induced to expand using IL-12 or IL-15, so as to mount a substantial graft versus leukemia (GvL) effect. The main disadvantage of UCB is the low stem cell yields, resulting in higher rates of graft failure as well as delayed time to engraftment compared to BMT. One rational approach to overcome this limitation involves ex vivo expansion of UCB derived hematopoietic precursors. In this review we tried to answer the question: UCBT how, when and for whom. This procedure is mostly applicable for children and especially those with indication for full allogeneic transplantation but who lack a matched sibling donor. Experimental approaches including ex vivo expansion of CB with cocktail of hematopoietic growth factors, with or without differentiation blocking agents, co-transplantation of haploidentical and CB cells or co-transfusion of CB and mesenchymal cells may enable successful UCBT in adults and probably will result in expanding the indication to solid tumors or autoimmune disorders.

Fanconi anaemia and leukaemia - clinical and molecular aspects

Fanconi anaemia (FA) is an autosomal recessive chromosomal instability disorder, which is characterized by congenital abnormalities, defective haemopoiesis and a high risk of developing acute myeloid leukaemia and certain solid tumours. It can be caused by mutations in at least eight different genes. Molecular studies have established that a common pathway exists, both between the FA proteins and other proteins involved in DNA damage repair such as NBS1, ATM, BRCA1 and BRCA2. This review summarizes the general clinical and specific haematological features and the current management of FA. Recent molecular advances will also be discussed in the context of the cellular and clinical FA phenotype, with particular emphasis on the haematological aspects of the condition.

Nonmyeloablative stem cell transplantation: reduced-intensity conditioning for cancer immunotherapy—from bench to patient bedside

Despite major progress in treating hematologic malignancies and, to a lesser extent, metastatic solid tumors, much work remains ahead. With the anticancer potential of immunotherapy not yet fully exploited, patients with leukemia, malignant lymphoma, and other hematologic malignancies for which high-dose chemoradiotherapy is frequently recommended in conjunction with stem cell transplantation (SCT) can now benefit from the advantages of immunotherapy mediated by cytokines or alloreactive donor lymphocytes, while minimizing procedure-related toxicity and mortality. The feasibility of applying allogeneic cell-mediated immunotherapy in conjunction with allogeneic SCT following reduced-intensity conditioning, with minimal toxicity and no serious transplant-related complications, makes it possible to undertake such procedures on an outpatient basis as well as to offer an option for cure to elderly individuals and patients with less than optimal performance status. Being well tolerated, reduced-intensity transplants also offer a chance for cure to patients with otherwise resistant leukemia and malignant lymphoma who have relapsed after autologous SCT. Thus, the traditional obstacle of very high transplant-related toxicity and mortality due to multiorgan failure from cumulative toxicity of multiple anticancer agents and radiation therapy is overcome. Although immunotherapy mediated by allogeneic lymphocytes can be most effective, the immune potential of donor lymphocytes should be maximized by nonspecific or specific activation in vitro or in vivo, or both, for more effective eradication of resistant tumor cells, including in patients with bulky disease. More important is the challenge to target donor lymphocytes to the tumor and minimize their capacity to induce responses against normal host tissues, which frequently results in severe acute and chronic graft-versus-host disease (GVHD). Alternatively, donor lymphocytes should be eliminated as soon as tumor eradication is completed, or as soon as severe GVHD becomes prohibitive. Based on available experience, clinical application of innovative therapy, especially at the stage of minimal residual disease (MRD), may open new horizons for the treatment of malignancies considered until recently to be incurable. The feasibility of controlling cancer by targeted chemotherapy, best illustrated by the phenomenal activity of imatinib in patients with chronic myelogenous leukemia and, more recently, in gastrointestinal stromal tumors (including in patients fully resistant to all known anticancer agents) suggests that in the future, tumor-specific chemotherapy may represent the ultimate goal for achieving a stage of MRD with minimal multiorgan toxicity. Together, the combination of immunotherapy and targeted chemotherapy may provide the most logical approach for making real progress in controlling resistant hematologic malignancies and metastatic solid tumors.

Preparative therapies used for those with Fanconi's anemia undergoing stem cell transplants and subsequent engraftment rates

Fanconi anemia patients are often treated with stem cell transplants to prevent myelodysplastic changes or leukemic progression. A variety of preparative regimens have been utilized. A case of a 13-year-old child with Fanconi's anemia is presented to highlight the preparative therapy utilized, engraftment rates which have been seen and the incidence of graft-vs.-host disease (GvHD). A review of the literature suggests the most successful preparative therapies with the highest engraftment rates and also suggests the best GvHD regimens.

Graft-versus-Host Disease, the Graft-versus-Leukemia Effect, and Mixed Chimerism following Nonmyeloablative Stem Cell Transplantation

Allogeneic bone marrow or blood stem cell transplantation represents an important therapeutic tool for the treatment of otherwise incurable cancer and a large spectrum of nonmalignant diseases. Until recently, bone marrow transplantation was used primarily to eliminate malignant, genetically abnormal, or otherwise deficient stem cells; hence, highly toxic myeloablative regimens were considered mandatory for the eradication of undesirable cells of host origin. Recent data suggest that high-dose chemoradiotherapy may be successively replaced by nonmyeloablative stem cell transplantation (NST), which represents a safer biologic tool that involves the induction of host-versus-graft transplantation tolerance. NST thus provides allogeneic donor lymphocytes with the capacity to induce immune-mediated graft-versus-malignancy effects, either against mismatched minor or major histocompatibility alloantigens or against tumor-specific or tumor-associated antigens expressed by tumor or other hematologic cells of host origin. The future goals of the wider and safer clinical application of NST for the treatment of a larger number of indications and larger numbers of patients in need depend, on the one hand, on the development of more effective and safer modalities for maximizing the antitumor potential of donor lymphocytes (T-cells as well as natural killer and natural killer T-cells). On the other hand, these goals depend on using more selective approaches for targeting anticancer effector cells to their target cells. Such changes will thus set the stage for smarter rather than stronger modalities for the treatment of malignant and life-threatening nonmalignant diseases.

Non-TBI stem cell transplantation protocol for Fanconi anaemia using HLA-compatible sibling and unrelated donors

Allogeneic haemopoietic stem cell transplantation (SCT) is the only curative option for severe bone marrow (BM) failure in patients with Fanconi anaemia (FA). We have developed a non total body irradiation (TBI) conditioning protocol consisting of fludarabine (120-150 mg/m(2)), low dose of cyclophosphamide (40 mg/kg) and antilymphocyte globulin (45 mg/kg). Graft-versus-host disease (GVHD) prophylaxis was with cyclosporin alone for sibling allografts but also included Campath-1 H (days 1-5 post SCT) for the unrelated allografts. We have performed two sibling and two unrelated BM transplants with a follow-up of 11-51 months. All patients experienced minimal toxicity and were discharged from hospital 28-32 days post SCT. Neutrophil and platelet engraftment occurred from days 11 to 19 and 15 to 34, respectively. All patients achieved stable full donor haemopoiesis with normalisation of the peripheral blood count despite one of them having myelodysplasia (MDS) with 8% blasts prior to the SCT. The only site of acute GVHD was in the skin (grade I-II) and only one patient progressed to limited chronic GVHD. This protocol is associated with reduced toxicity and prompt engraftment in FA patients with AA and/or MDS undergoing SCT using sibling or unrelated donors.

Immunotherapy of hematologic malignancies and metastatic solid tumors in experimental animals and man

New approaches are needed for maximizing specific responses against tumor cells resistant to chemotherapy. While cytokine therapy may amplify natural resistance against minimal residual disease, more robust anti-leukemia reactivity can be provided by allogeneic bone marrow transplantation (BMT) in conjunction with myeloablative, hence hazardous, conditioning, at the cost of graft-versus-host disease (GVHD). Documentation of the capacity of donor lymphocyte infusion (DLI) given late post BMT, when patients were off immunosuppression, in early 1987, with successful reversal of relapse and cure of patients fully resistant to maximally tolerated doses of chemoradiotherapy, with many patients alive and well >10-15 years later, indicated two important facts. First, resistant tumors are unlikely to be cured with higher doses of chemoradiotherapy that may harm the patient but not eliminate all his clonogenic tumor cells. Second, that under condition of tolerance to donor alloantigens, DLI may provide a cure to otherwise resistant patients. These observations paved the road for clinical application of non-myeloablative stem cell transplantation (NST), in the early 90s, based on a two-step procedure, first involving induction of transplantation tolerance to donor alloantigens by engraftment of donor stem cells, following safe lymphoablative rather than myeloablative conditioning. Second, use of donor lymphocytes for elimination of residual tumor or otherwise abnormal hematopoietic cells by immune-mediated graft-versus-host effects inducible by mobilized blood stem cell allografts containing larger inocula of donor T cells, or supported by post-grafting DLI when patients were off immunosuppressive modalities.

Low-intensity hematopoietic stem-cell transplantation across human leucocyte antigen barriers in dyskeratosis congenita

Since the results of conventional hematopoietic stem-cell transplantation (HSCT) for patients with dyskeratosis congenita (DC) are poor owing to the high incidence of transplant-related complications, we explored the use of a low-intensity HSCT regimen. We report two children with DC with severe cytopenia, who underwent successful HSCT from a matched unrelated donor after conditioning with fludarabine, cyclophosphamide, and antithymocyte globulin. Graft-versus-host-disease (GVHD) prophylaxis consisted of corticosteroids and cyclosporin A. The regimen was well tolerated, no significant transplant-related complications were observed, and engraftment was rapid and complete. At 15 and 16 months after HSCT, the children were fully engrafted, in excellent clinical condition, full-donor chimerism, and no signs of GVHD. We conclude that a low-intensity regimen is sufficient to induce durable engraftment using matched unrelated donor HSCT in DC patients, with minimal 1-year transplant-related toxicity. Longer follow-up will determine whether this regimen also reduces long-term toxicity.

Successful T-cell-depleted, related haploidentical peripheral blood stem cell transplantation in a patient with Fanconi anaemia using a fludarabine-based preparative regimen without radiation

Haematopoietic stem cell transplantation (HSCT) represents the treatment of choice for severe bone marrow failure in patients with Fanconi anaemia (FA). When the donor is a compatible relative, the chance of being cured with an allograft is in the order of 70%. However, for FA children lacking an HLA-identical sibling, the results of HSCT from an alternative donor are less satisfactory because of a higher risk of graft rejection, graft-versus-host-disease (GVHD) and regimen-related toxicity. We report on a 12-year-old girl with FA, who was treated by T-cell-depleted (TCD) peripheral blood HSCT from her haploidentical uncle, using a novel fludarabine-based preparative regimen without radiation. She had rapid engraftment with no toxicity and no GVHD. Progressive recovery of both numbers of lymphocyte and of proliferative response to polyclonal activators occurred over time. At 18 months after transplantation, she is well with 100% donor chimerism and has recovered normal immune function.

Stem cell transplantation from HLA-matched related donor for Fanconi's anaemia: a retrospective review of the multicentric Italian experience on behalf of AIEOP-GITMO

Twenty-seven consecutive Italian patients with Fanconi's anaemia (FA) underwent stem cell transplantation (SCT) from an HLA-matched related donor in 10 Italian centres of the Associazione Italiana Ematologia ed Oncologia Pediatrica (AIEOP), Gruppo Italiano di Trapianto di Midollo Osseo (GITMO). Twenty-two patients (81.5%) were conditioned with low-dose (median 20 mg/kg) cyclophosphamide (Cy) and thoraco-abdominal or total body irradiation (median dose 500 cGy), five patients (18.5%) with high-dose Cy (median 120 mg/kg). Graft-vs.-host disease (GVHD) prophylaxis was carried out with cyclosporin A in 26 cases; methotrexate (MTX) was added in eight cases. One patient received MTX alone. The median follow-up was 36 months. Ninety-two percent of patients (25 out of 27) engrafted, grade II and III acute GVHD occurred in 28% and 8% of patients, respectively, with chronic GVHD in 12.5%. Conditioning-related toxicity was mild: 4% of patients had grade III mucositis, 7.4% had grade II haemorrhagic cystitis, 14.8% had grade III liver toxicity and 11.1% had grade III renal toxicity. Transplant-related mortality at 12 months was 19.2%, survival at 36 months was 81.5%, with a median Karnofsky score of 100%. No late tumours occurred after a mean follow-up of the survivors of 5 years. None of the studied variables significantly affected the survival, including conditioning regimen, acute GVHD and clinical non-haematological phenotype. Among the studied variables, only conditioning regimens containing high-dose Cy and the presence of genital abnormalities were significantly (P < 0.05) associated with an increased rate of acute GVHD. Our study demonstrates that the Italian FA patients undergoing SCT from an HLA-matched related donor have a very good outcome. These patients, when compared with others of different ethnic origin who underwent allogeneic bone marrow transplantation, showed a less severe non-haematological phenotype, raising the possibility that this milder phenotype may have, at least in part, contributed to the outcome. Our data may provide a useful tool for further studies aiming to correlate genotype with phenotype.

Umbilical cord blood transplants

With the establishment of cord blood banks, the number of related and unrelated umbilical cord blood transplants is increasing worldwide. Close links have been established with the cord blood banks. Available data showed that umbilical cord blood transplants offer overall results comparable to those obtained with related or unrelated bone marrow transplants. Several differences were found: engraftment with cord blood was delayed, resulting in an increased incidence of early transplant complications, and the incidence of acute and chronic graft-versus-host disease was significantly reduced with cord blood grafts, even in HLA-mismatched transplants and in adults. In patients with leukemia, the rate of relapse appeared to be similar to that documented in bone marrow transplant recipients. These data confirm the potential benefit of using umbilical cord blood hematopoietic stem cells for allogeneic transplants.

Fludarabine-based protocol for haploidentical peripheral blood stem cell transplantation in Hurler syndrome

To assess the feasibility of performing a haploidentical peripheral blood stem cell transplantation (PBSCT) in a child with Hurler syndrome after a novel conditioning regimen consisting of fludarabine monophosphate, anti-T-lymphocyte globulin, low-dose busulfan, and single-dose total body irradiation of 750 cGy. A 16-month old boy with Hurler syndrome underwent haploidentical PBSCT from his 3/6 HLA-matched sister. Pretransplant conditioning consisted of fludarabine (30 mg/m2 per day) from day -10 to day -5, busulfan (4 mg/kg per day) on days -7 and -6, rabbit anti-T-lymphocyte globulin (10 mg/kg per day) from day -4 to day -1, and total body irradiation of 750 cGy on day -1. In vitro T-cell depletion was carried out with rat antihuman CDw52 monoclonal antibody (Campath-1G). The fludarabine-based protocol was well-tolerated, with mild toxicity and no major transplant-related complications or graft-versus-host disease. Engraftment was complete and stable. Chimerism was 100% donor origin, as determined by restriction fragment length polymorphism. Cytogenetic and polymerase chain reaction-various number of tandem repeats (PCR-VNTR) analyses of peripheral blood and bone marrow showed 100% reconstitution with female donor cells. The patient underwent the transplant 30 months ago and is in good clinical condition, with normal counts, no signs of graft-versus-host disease, and no infectious episodes; neurologic signs have stabilized. Haploidentical PBSCT, T-cell-depleted by means of Campath-1G, may serve as a therapeutic alternative for patients with Hurler syndrome when a fully matched sibling is not available.