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

Fanconi anemia phenotypic and transplant outcomes' associations in Iranian patients

Objectives

Fanconi anemia (FA) is a rare, heterogeneous, inherited disorder. Allogeneic hematopoietic stem cell transplantation (HSCT) represents the only therapeutic option to restore normal hematopoiesis. This study reports the outcomes of FA‐HSCT patients and identifies factors, including clinical phenotype. Our team examined more than 95% of Iranian FA patients during the last decade.

Study Design

One hundred and six FA patients (age range: 2–41) who underwent HSCT from March 2007 to February 2018 were enrolled. Clinical characteristics of genetic disease, pre‐HSCT findings, HSCT indication, and long‐term follow‐up evaluated and recorded. Data were analyzed using SPSS 19.0.

Results

The mean follow‐up period for survivors was 36 months (range, 1–101). The 3‐year overall survival (OS) and disease‐free survival were 72.2% and 71.2%, respectively. The 3‐year OS rate for patients with limited and extensive malformations was 78.8% and 56.6%, respectively (p = 0.025). Acute graft versus host disease incidence was 60.52% for patients with limited malformations versus 70% for patients with extensive ones (p = 0.49). Chronic graft versus host disease incidence for these two groups was 9.21% and 10%, respectively (p = 0.91).

Conclusions

OS was not associated with each of the malformations singly; however, it was lower in the extensive group. The younger age of patients at the HSCT time leads to a higher OS. The differences in FA patients' outcomes and the various genotypes were probably related. These data provide a powerful tool for further studies on genotype–phenotype association with HSCT results.

The younger age of FA patients at the HSCT time leads to a higher OS.

OS was lower in the congenital malformations extensive group.

The malformations’ scope affects aGvHD incidence significantly, while not cGvHD.

Various HSCT outcomes in different centers can be due to distinct genotypes.

Successful Outcome With Fludarabine-Based Conditioning Regimen for Hematopoietic Stem Cell Transplantation From Related Donor in Fanconi Anemia: A Single Center Experience From Turkey

BACKGROUND

Fanconi anemia (FA) is a heterogeneous autosomal recessive (and rarely X linked) disorder, which is characterized by congenital malformations, progressive bone marrow failure, and predisposition to malignancies. Hematopoietic stem cell transplantation (HSCT) is the only definitive treatment for the hematological manifestations in FA.

PROCEDURE

Twenty-seven patients with FA underwent HSCT using fludarabine (Flu) based regimen at our center between April 2004 and May 2014. One patient who developed acute leukemia before HSCT was excluded from the study. The remaining 26 patients were included. The median age of the patients at the time of transplantation was 9.6 years (range 5.6-17.0 years) and male/female ratio was 19/7. Donors were Human leukocyte antigen (HLA)-identical sibling in 18 patients, HLA-identical other relatives in six patients, and HLA 1-antigen mismatched sibling in two patients. Conditioning regimen consisted of Flu, cyclophosphamide, and antithymocyte globulin.

RESULTS

All patients engrafted but one developed poor graft function and underwent second HSCT. Acute graft versus host disease (GVHD) (≥grade 2) occurred in two patients (7.6%) and chronic GVHD in one patient (3.9%). Three patients developed venoocclusive disease (11.5%). Survival rate was 96.2% (25/26) at a median follow-up of 54 months (10-131 months) and all patients who survived were in good clinical condition. None of the patients developed secondary malignancy during the follow-up period.

CONCLUSIONS

The present study from Turkey, a middle-income country, shows successful transplant outcome with low toxicity using Flu-based conditioning in patients with FA who underwent HSCT from HLA-related donors.

Matched sibling donor stem cell transplantation for Fanconi anemia patients with T-cell somatic mosaicism

SCT from HLA-identical sibling donors is generally associated with an excellent survival in FA patients if performed prior to the development of MDS or leukemia. However, the optimal conditioning regimen has not been defined. We report here our experience with 15 Japanese FA patients who underwent HLA-matched sibling donor SCT. The aim of this study is to compare radiation-based conditioning to Flu-based conditioning for FA patients in a Japanese population where the T-cell somatic mosaicism is higher than in the Caucasian population. Eight patients (a-group) received a radiation-based conditioning (500-600 cGy of thoracoabdominal/TBI) with CY dose modification (20-120 mg/kg), and ATG; two patients exhibited rejection. Seven patients (b-group) received CY (40 mg/kg), 150-180 mg/m(2) of Flu, and ATG. Durable engraftment was demonstrated in all patients. In FA patients, Flu-based conditioning may allow stable engraftment in matched sibling donor transplantation without radiation, even in patients with T-cell somatic mosaicism.

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.

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.