Allogeneic Hematopoietic Stem Cell Transplantation In Fanconi Anemia

25 Pages·2013·0.28 MB·English

From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
Blood First Edition Paper, prepublished online October 21, 2013; DOI 10.1182/blood-2013-01-479733
Allogeneic Hematopoietic Stem Cell Transplantation
In Fanconi Anemia: the EBMT experience

Régis Peffault de Latour1#, Raphael Porcher2#, Jean-Hugues Dalle3, Mahmoud Aljurf4, Elisabeth T Korthof5,
Johanna Svahn6, Roelof Willemze7, Cristina Barrenetxea8, Valerie Mialou9, Jean Soulier10, Mouhab Ayas4, Rosi
Oneto11, Andrea Bacigalupo11, Judith C. W. Marsh12, Christina Peters13, Gerard Socie1,14* and Carlo Dufour15*
on behalf of the FA committee of the Severe Aplastic Anemia Working Party (SAA WP) and the Pediatric
Working Party (PD WP) of the European Group for Blood and Marrow Transplantation (EBMT)

1Service d’Hématologie Greffe, AP-HP-Hôpital Saint Louis, Paris, France; 2Department de biostatistique
Médicale AP-HP-Hôpital Saint Louis, Paris, France; 3Service d’Hématologie Pédiatrique, AP-HP-Hôpital Robert
Debré Paris, France; 4Oncology Centre, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi
Arabia; 5Pediatric Stem Cell Transplantation, Leiden University Medical Center, Leiden, Netherlands; 6Pediatric
Hematology, Ospedale Gaslini, Genova, Italy; 7Dept. of Hematology, Leiden University Medical Center, Leiden,
the Netherlands; 8Hospital Vall d’Hebron, Barcelona, Spain; 9Institut d’Hematologie et d' Oncologie Pediatrique,
Lyon, France; 10INSERM U944 and Hematology lab, Saint-Louis Hospital and University Paris-Diderot, Paris,
France; 11Department of Hematology, Ospedale San Martino, Genova, Italy; 12Haematological Medicine, King's
College Hospital/ King's College London, London, United Kingdom; 13Stem Cell Transplantation Unit, St. Anna
Children's Hospital & EBMT-PDWP, Vienna, Austria, 14Université Paris-Diderot, Paris, France U728, Paris,
15Pediatric Hematology, G. Gaslini Institute, Genova, Italy

#RPL and RP share the first authorship, *GS and CD share the last authorship

Regular Article, Running head: Stem Cell Transplantation and Fanconi Anemia;
Keywords: Fanconi anemia, Allogeneic stem cell transplantation, secondary malignancy

This work was presented orally at the annual meeting of the American Society of Hematology (San Diego
2011; abstract #325)

Correspondence to:
Dr. Régis Peffault de Latour ; Service d’Hématologie Greffe, Hôpital Saint Louis, Paris, France ; Phone: +33 1 42
38 50 73, Fax: [phone], E-mail: [email protected]
1
Copyright © 2013 American Society of Hematology
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
Key Points

- Best survival benefit of HSCT is observed in FA patients transplanted before 10 years with
bone marrow following a fludarabine-based regimen.

- Long-term outcome of FA patients after transplantation is mainly affected by secondary
malignancies and chronic graft versus host disease.

Abstract

Although allogeneic hematopoietic stem cell transplantation (HSCT) remains the only
curative treatment for patients with Fanconi Anemia (FA), published series mostly refer to
single center experience with limited numbers of patients. We analyzed results in 795 FA
patients who underwent first HSCT between May 1972 and January 2010. With a six-year
median follow-up, overall survival (OS) was 49% at 20 years (95%CI 38–65). Better outcome
was observed for patients transplanted after the age of 10 years, before clonal evolution (i.e.
myelodysplastic syndrome or acute myeloid leukemia), from a matched family donor,
following an irradiation-free containing conditioning regimen, the latter including
fludarabine. Chronic graft versus host disease (GvHD) and secondary malignancy were
deleterious when considered as time dependent covariates. Age more than 10 years at time
of HSCT, clonal evolution as an indication for transplantation, peripheral blood as source of
stem cells and chronic GvHD were found independently associated with the risk of
secondary malignancy. Changes in transplant protocols have significantly improved the
outcome of FA patients, who should be transplanted at a young age with bone marrow as
the source of stem cells.
2
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
Introduction

Fanconi anemia (FA) is a rare, phenotypically heterogeneous, inherited disorder clinically
characterized by congenital abnormalities, progressive bone marrow failure (BMF) and a
predisposition to develop malignancies, especially acute myeloid leukemia (AML) and
squamous cell carcinoma (SCC)1-5. Hematopoietic stem cell transplantation (HSCT) still
represents the only curative option for bone marrow failure (BMF) 6-9, although it does not
prevent the occurrence of solid tumors, mostly in the head and neck10.
Conditioning regimens based on reduced doses of cyclophosphamide, either alone or
with limited field radiotherapy, have cured BMF in a large proportion of patients
transplanted from an HLA-identical sibling6,11,12. Results of unrelated donor (UD) HSCT have
been less encouraging however, mainly due to increased engraftment failure and higher
incidences of both acute and chronic graft-versus-host disease (GvHD)7,13, although better
results were recently reported8,9,14. The use of fludarabine-based reduced intensity
conditioning regimens with or without T-cell depletion8,9,14-17 seems to contribute to this
improvement, as well as better supportive care18 and probably better HLA typing, as shown
in other non-malignant diseases19,20.
However, some questions remain unanswered in this particularly difficult and rare
clinical situation. What is the best source of stem cells to transplant a non-malignant disease
where the risk of graft failure is high? What are the factors affecting the long-term outcome
post-HSCT? It has been difficult to answer these questions until now, since only a few
registry reports on more than 50 patients with FA have been published6-9. To address these
issues, we performed an analysis on the largest cohort of FA patients post-HSCT ever studied
so far.
3
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
Patients, materials and methods

Data collection
This retrospective multi-center study was conducted through the Severe Aplastic Anemia
(SAA) and the Pediatric Working Parties of the European group for Blood and Marrow
Transplantation (EBMT). The EBMT maintains a registry in which participating centers report
consecutively transplanted patients. Data management is performed by each center
independently. An additional questionnaire was sent to all centers with FA patients requiring
more specific details regarding FA: clinical characteristics at time of transplant (growth
retardation, skin hypopigmentation and somatic malformations), indication for stem cell
transplantation and long-term follow-up. All data were carefully checked and institutions’
physicians were contacted (RPL and/or RP) if there were any inconsistencies. Some of the
patients have already been previously reported7,10,21,22. All patients or legal guardians
provided informed consent according to the Declaration of Helsinki. The study was approved
by the local IRBs of the participant centers.

Inclusion criteria
All consecutive patients with FA who underwent first allogeneic stem cell transplantation
from an HLA-matched related or unrelated donor and who have been reported to EBMT
were included. Sibling and unrelated donors and recipients were matched if HLA A and B
were identical at the generic level and HLA DRB1 at the allelic level. Patients were included if
an increase was observed in lymphocyte chromosome breaks after exposure to DNA cross-
linking agents. Patients who received cord blood or haplo-identical transplants were not
included in the study, as well as patients who received 1 or more antigen mismatched
related donors.

End points
Myelodysplastic syndrome and AML were defined according to classical definition23,24.
Engraftment was defined as achieving an absolute neutrophil count of 0.5 x 109/L for at least
three consecutive days. Acute GvHD (aGvHD) and chronic GvHD (cGvHD) were defined and
graded according to previous published criteria25,26. For acute GvHD, time to GvHD was
randomly selected using random sampling with replacement in empirical distribution in
4
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
cases where dates were missing. Non-relapse mortality (NRM) was defined as any cause of
death other than return of marrow to its status before transplant. Survival was calculated
from the date of transplantation to the date of last follow-up or date of death from any
cause.

Statistical methods
Analysis was carried out at the reference date of January 4, 2011. Data are presented as
numbers (and percentages). Death was considered as a competing risk in the analyses of
acute and chronic GvHD. For competing risk analyses, cumulative incidence functions (CIF)
were estimated27. Factors associated with outcomes were analyzed using Fisher's exact tests
and logistic regression models (engraftment), Gray's tests and Fine-Gray regression
model28,29 (acute GvHD), proportional hazards models for the cause-specific hazard30
(chronic GvHD and NRM) and Cox proportional hazards models (OS). The proportional
hazards assumption was checked by examination of Schoenfeld residuals and Grambsch and
Therneau’s lack-of-fit test31. In case of non-proportional hazards, models with time-varying
effects were also fitted. Interaction between donor and other variables were tested. When
the number of events was sufficient, all considered potential predictors were entered in the
models. Otherwise, a stepwise variable selection procedure was used to limit the models to
at least 5 events per variable, as it has been shown to have similar properties than the usual
10 events per variable rule for survival models32. In case of missing data, multiple
imputations were used which allowed creating several datasets where missing data were
predicted (detailed in appendix 1)33,34. All tests were two-sided and P 0.05 was considered
≤
as indicating significant association. Analyses were performed using the R statistical software
version 2.15.0.
5
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
Results

Study cohort
From 1972 to 2009, data from 795 consecutive patients with FA who underwent their first
allogeneic HSCT from an HLA-matched donor were reported to the EBMT by 150 centers
(HLA-identical sibling; N = 471 / HLA-matched unrelated donor; N = 324): 90% were
performed after 1990 and 49% were performed after 1999 (N = 390). The median follow-up
time of the study group was 6 years (range 0 months to 28 years). Patient, disease, and
transplantation characteristics are shown in Table 1.

Engraftment and graft versus host disease (GvHD)
The probability of graft failure was 11% (95% confidence interval [95%CI] 9 to 14) (8% for
primary and 3% for secondary graft failure). Engraftment rates according to donor type and
transplantation period are shown in Table 2. The probability of graft failure was higher in
patients transplanted for clonal evolution (myelodysplastic syndrome or AML) than for
aplastic anemia with only pancytopenia (HR 3.17 [95%CI 1.60 to 6.28], P=0.001), patients
who received ex-vivo T-cell depleted graft (HR 2.19 [1.15 to 4.15], P=0.017) and lower in
patients who had received a fludarabine-based regimen (HR 0.31 [0.12 to 0.78], P=0.013)
(Supplementary Table 1 & 2). Patients received mainly a cyclosporine-based GvHD
prophylaxis regimen (>90%). Grade II-IV acute GvHD was 32% (95%CI 29 to 36) and chronic
GvHD was 14% and 19% at 1 year and 5 years, respectively. Cumulative incidence (CIF) of
GvHD (according to donor type and transplantation period) is shown in Table 2. In
multivariate analysis, the only independent predictor for acute GvHD was the use of stem
cells of an unrelated donor (HR 1.42 [1.08 to 1.87], P=0.013). Fludarabine in the conditioning
regimen was found to be protective (HR 0.49 [0.48 to 1.00], P=0.048). Forty-one patients
(17%) had at least three malformations with no association with a higher risk of acute GvHD.
In multivariable analysis, independent predictors for chronic GvHD included HSCT in patients
between 10 and 20 years (HR 1.40 [1.01 to 1.96], P=0.045) and in patients older than 20
years (HR 2.22 [1.24 to 4.00], P=0.008) or in patients with previous history of acute GvHD
(HR 3.40 [2.47 to 4.68], P<0.0001).

6
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
Overall survival (OS)
The OS probability was 65% (95%CI 61 to 68) at 5 years, 52% (95%CI 47 to 58) at 15 years
and 36% (95%CI 28 to 47) at 20 years (Figure 1A). Non-relapse mortality (NRM) was 24%
(95%CI 21 to 28) at 1 year and 29% (95%CI 25 to 32) at 5 years. Concerning the 58 patients
transplanted for AML or MDS, the cumulative incidence of relapse at 12 months was 7%
(95%CI 1 to 22) for patients with an HLA-identical sibling donor and 14% (4 to 30) for
patients with HLA-matched unrelated donors. Cumulative incidences at 60 months were 7%
(1 to 22) and 20% (7 to 38), respectively (P=0.22). Improved OS was observed in patients
transplanted after the year 2000 (HR: 0.64; 95%CI 0.50-0.81; P=0.0003) (Figure 1B) or from a
sibling donor (Figure 1C & 1D). NRM and OS are described according to study period in Table
2. During follow-up, 305 patients died. The principal 3 causes of death were GvHD (n=105,
34%); infections (n=83, 27%) and secondary malignancies (n=30, 10%) (Table 3). The effects
of stem cell source (peripheral blood versus bone marrow), as well as the presence of
fludarabine, ATG or TBI within the conditioning regimen after 1999, are presented according
to donor type in Supplementary Figure 1. Factors associated with OS are shown in Table 4
(analysis on imputed datasets), and supplementary Table 3 for the analysis on available data.
Of note, the effect of donor type (sibling versus unrelated) was found to vary during follow-
up. Patients with HLA-matched unrelated donors thus experienced a significantly higher
hazard of death within the first year post-SCT, while 1-year survivors showed a lower hazard
of death long-term in this setting. However, survival for patients transplanted from an HLA-
matched unrelated donor was clearly lower compared with those who received an HLA-
matched family donor on the entire follow-up period. Chronic GvHD and the occurrence of a
secondary malignancy were independently associated with the hazard of death when
considered as time-dependent covariates: HR 3.10 (2.18 to 4.39), P<0.0001 for chronic GvHD
and HR 23.0 (13.3 to 40.1), P<0.0001) for secondary malignancies. Regarding somatic
malformations, patients with at least 3 malformations (n=41, 17%) did not show any
difference in terms of OS when compared with those whose malformations were limited (HR
0.94 [0.55 to 1.60], P=0.81).

Secondary malignancies
Overall, the 15-year CIF of secondary malignancies was 15% (95%CI 11 to 20). For patients
who survived more than one year (N = 509), the 15-year CIF was 21% (95% CI 14 to 28) and
7
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
34% (95% CI 23 to 46) at 20 years (Figure 2). Solid tumor accounted for 89% of all secondary
malignancies: 20 patients were diagnosed with squamous-cell carcinoma
(mouth/tongue/oesophagus for 13, vulvo-vaginal for 1, lung for 1, and unspecified for 5), 21
patients were diagnosed with solid tumor but localization was missing. Others consisted in 1
lymphoma, 4 acute leukemia and 4 myelodysplastic syndromes. Independent risk factors for
secondary malignancies included age at HSCT: between 10 and 20 years (HR 2.32 [1.27 to
4.25], P=0.006) and more than 20 years (HR 3.30 [1.05 to 10.3], p=0.041), clonal evolution as
an indication for HSCT (HR 4.56 [1.67 to 12.5], P =0.003), peripheral blood as source of stem
cells (HR 3.29 [1.30 to 8.35], P =0.012) and previous chronic GvHD (time-dependent) (HR
3.26 [1.81 to 5.88], P <0.0001). Irradiation in the conditioning regimen and donor type did
not correlate with secondary malignancies.
8
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
Discussion

This retrospective, multicenter-study evaluated the outcome of 795 patients with FA who
underwent a first allogeneic HSCT during the last 40 years in Europe. We documented a
substantial reduction in the hazard of death related to allogeneic HSCT, as well as improved
long-term survival in recent years (>1999), especially in patients transplanted from unrelated
donors. Patients transplanted before the age of 10 years experienced lower risk of both
chronic GvHD and secondary cancer, as well as better long-term overall survival. The use of a
fludarabine-based conditioning regimen was associated with better engraftment, lower rate
of acute GvHD and eventually better long-term OS. Despite obvious improvement in recent
years, the prospects for long-term survival in FA patients after HSCT is still largely affected by
secondary malignancies (of which 89% are solid tumors) directly associated with death. Age
at HSCT and chronic GvHD, use of peripheral blood as source of the stem cells, and clonal
evolution at the time of HSCT were identified as risk factors for secondary malignancies.

This study spanning 40 years on almost 800 patients with FA transplanted in Europe
represents the largest group ever reported and offers a unique opportunity to describe and
analyze HSCT practice as well as risk factors associated with outcomes in this rare disease.
The median follow-up of 6 years may appear short regarding the 40 years period study.
However, the reason is that almost all patients transplanted before 1985 died within the 15
years of follow-up post-HSCT and almost half of the population were transplanted after
2001. Overall, patients who were transplanted with stem cells from an HLA-identical sibling
still have a better probability of survival than those transplanted with an unrelated
transplant. The 5-year OS post-HSCT for patients transplanted from an HLA-identical sibling
improved slightly over time (68% until the year 2000, compared with 76% thereafter).
Conversely, the 5-year OS of patients transplanted after the year 1999 from an unrelated
donor was 64%, which is much better compared with the 49% observed prior to this date
and compares favorably with results from other studies7-9. This was mainly due to decreased
NRM after 1999. Several modifications in our transplant practice might have contributed to
this substantial reduction in the hazard of mortality, including improved supportive care,
HLA typing19,20,35-37 and possibly the use of fludarabine-based regimens, improving
engraftment, decreasing acute GvHD and eventually associated with better OS. Other factors
9
From www.bloodjournal.org by guest on March 30, 2019. For personal use only.
than donor type and fludarabine have been associated with detrimental OS and have been
published, such as older age or clonal evolution at time of HSCT, a long delay from diagnosis
to HSCT (>12 months), donor/ recipient CMV status (negative/positive or positive/positive)
(for a review, see McMillan38 BJH). The role of more accurate HLA allelic matching of
unrelated donors in improving outcomes cannot be readily ascertained from these data
since only incomplete information on this factor was available in our patients.

Despite better HLA typing in recent years, the risk for GvHD did not change drastically and
contributed either directly to early mortality or subsequently as a major risk factor for
secondary cancer, as previously described9,21,39. We did not find a correlation between
malformations and acute GvHD, as previously suggested7,21. Reducing acute GvHD would
improve both early and late outcomes. Fludarabine was associated with a lower rate of
acute GvHD in our study. Ex vivo as well as in vivo T-cell depletion has been shown to
dramatically reduce the incidence of acute GvHD after related40 or unrelated
transplantation8 in patients with FA. Prospective, randomized studies using anti-thymocyte
globulin demonstrated a lower rate of both acute and chronic GvHD and may thus be of
particular interest in this setting41,42. A TBI-dose-escalation study associated with T-cell
depleted marrow grafts was not associated with increased toxicity, but rates of graft failure
remained high43. We also identified ex vivo T-cell depletion as a risk factor for graft failure in
our study while we found that the use of an irradiated-based conditioning regimen was
associated here with poor long-term outcome. A fludarabine-based preparative regimen,
which was associated with improved engraftment and better long-term OS, irradiation free,
should currently be the optimal strategy to consider in FA patients undergoing HSCT, by
avoiding an additional risk factor interacting with the main biologic defect of FA (i.e. DNA
repair processes).

While our study shows a drastic improvement in the risk of early mortality post HCT, long-
term OS was mainly affected by secondary malignancy. With a 6-year median follow-up, OS
after HSCT was 49% at 20 years. A 4.4-fold higher rate of squamous cell carcinoma has been
found compared with the rate in patients with FA of the same age who did not receive
transplants39. In the presence of competing causes of mortality, the cumulative incidence of
squamous cell carcinoma lies between 24% at 15 years39. Whether the high incidence of
10