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Bernasconi D.P.,University of Milan Bicocca | Rebora P.,University of Milan Bicocca | Iacobelli S.,University of Rome Tor Vergata | Iacobelli S.,European Group for Blood and Marrow Transplantation | And 2 more authors.
Statistics in Medicine | Year: 2016

The 'landmark' and 'Simon and Makuch' non-parametric estimators of the survival function are commonly used to contrast the survival experience of time-dependent treatment groups in applications such as stem cell transplant versus chemotherapy in leukemia. However, the theoretical survival functions corresponding to the second approach were not clearly defined in the literature, and the use of the 'Simon and Makuch' estimator was criticized in the biostatistical community. Here, we review the 'landmark' approach, showing that it focuses on the average survival of patients conditional on being failure free and on the treatment status assessed at the landmark time. We argue that the 'Simon and Makuch' approach represents counterfactual survival probabilities where treatment status is forced to be fixed: the patient is thought as under chemotherapy without possibility to switch treatment or as under transplant since the beginning of the follow-up. We argue that the 'Simon and Makuch' estimator leads to valid estimates only under the Markov assumption, which is however less likely to occur in practical applications. This motivates the development of a novel approach based on time rescaling, which leads to suitable estimates of the counterfactual probabilities in a semi-Markov process. The method is also extended to deal with a fixed landmark time of interest. © 2016 John Wiley & Sons, Ltd. Source

Mohty B.,University of Geneva | Mohty M.,Nantes University Hospital Center | Mohty M.,University of Nantes | Mohty M.,European Group for Blood and Marrow Transplantation
Blood Cancer Journal | Year: 2011

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective therapy for various malignant and non-malignant diseases. Many patients have now been followed for two or three decades posttransplant and are presumed to be cured. With the tremendous advances achieved in terms of supportive care, it is reasonable to expect outcomes to improve steadily and consequently increasing numbers of transplant survivors will be facing life after the initial transplant experience. Although long-term allo-HSCT survivors generally enjoy good health, for many others, cure or control of the underlying disease is not accompanied by full restoration of health. The burden of long-term morbidity borne by allo-HSCT survivors is substantial, and long-term follow-up of patients who received allo-HSCT is now widely recommended. Immediate survival is no longer the sole concern after allo-HSCT. The goals should also include complete recovery of the overall health status with normal physical and psychological functioning. Long-term side effects after allo-HSCT include non-malignant organ or tissue dysfunction, changes in quality of life, infections related to abnormal immune reconstitution and secondary cancers. Many of these can be attributed to the deleterious effects of chronic graft-versus-host disease. The aims of this review are to provide an update on the recent research evidence in the field. © 2011 Macmillan Publishers Limited All rights reserved. Source

Yanover C.,Fred Hutchinson Cancer Research Center | Petersdorf E.W.,Fred Hutchinson Cancer Research Center | Malkki M.,Fred Hutchinson Cancer Research Center | Gooley T.,Fred Hutchinson Cancer Research Center | And 4 more authors.
Immunome Research | Year: 2011

The success of hematopoietic cell transplantation from an unrelated donor depends in part on the degree of Human Histocompatibility Leukocyte Antigen (HLA) matching between donor and patient. We present a structure-based analysis of HLA mismatching, focusing on individual amino acid mismatches and their effect on peptide binding specificity. Using molecular modeling simulations of HLA-peptide interactions, we find evidence that amino acid mismatches predicted to perturb peptide binding specificity are associated with higher risk of mortality in a large and diverse dataset of patient-donor pairs assembled by the International Histocompatibility Working Group in Hematopoietic Cell Transplantation consortium. This analysis may represent a first step toward sequence-based prediction of relative risk for HLA allele mismatches. © 2011 Yanover et al; licensee Nikolai Petrovsky Publishing. Source

Morishima Y.,Japan Marrow Donor Program | Morishima Y.,Aichi Cancer Center Research Institute | Kawase T.,Japan Marrow Donor Program | Kawase T.,Aichi Cancer Center Research Institute | And 12 more authors.
Biology of Blood and Marrow Transplantation | Year: 2013

The significance of patient and donor ethnicity on risk of acute graft-versus-host disease (GVHD) and disease relapse after unrelated donor hematopoietic cell transplantation (HCT) is not known. A total of 4335 patient-donor pairs from the International Histocompatibility Working Group in HCT met the following 3 criteria: (1)HLA-A, -B, -C, -DRB1, and -DQB1 allele matched donor, (2) diagnosis of leukemia, and (3) non-T cell depleted GVHD prophylaxis. Posttransplantation risks of acute GVHD and leukemia relapse were defined in Asian/Pacific Islander, white, African American, Hispanic, and Native American patients that underwent transplantation from donors with the same self-described background. Asian patients had a significantly lower incidence of acute GVHD (Japanese patients: 40.0% grades II to IV and 15.3% grades III to IV; non-Japanese Asian patients: 42.1% grades II to IV and 15.7% grades III to IV) compared with white patients (56.5% grades II to IV and 22.6% grades III to IV) (P<.001). The hazard ratio of acute GVHD for white patients was significantly higher than for Japanese patients. Unexpectedly, the hazard ratio of leukemia relapse in white patients with early disease status was also significantly higher than that in Japanese patients. These results provide a platform for future investigation into the genetic factors for unrelated donor HCT and clinical implications of diverse ethnic background. © 2013 American Society for Blood and Marrow Transplantation. Source

De Latour R.P.,Service dHematologie greffe | De Latour R.P.,University Paris Diderot | De Latour R.P.,European Group for Blood and Marrow Transplantation | Soulier J.,University Paris Diderot | Soulier J.,French Institute of Health and Medical Research
Blood | Year: 2016

Fanconi anemia (FA) is the most frequent inherited cause of bone marrow failure (BMF). Most FA patients experience hematopoietic stem cell attrition and cytopenia during childhood, which along with intrinsic chromosomal instability, favor clonal evolution and the frequent emergence in their teens or young adulthood of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). To early identify and further predict bone marrow (BM) clonal progression and enable timely treatment, the follow-up of FA patients includes regular BM morphological and cytogenetic examinations. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative treatment of FA patients with MDS or AML. Although questions remain concerning HSCT itself (including the need for pretransplant chemotherapy, the best conditioning regimen, and the optimal long-termfollow-upofsuchpatients especially regarding secondary malignancies), clonal evolution in the absence of significant BMdysplasia and blast cells can be difficult to address in FA patients, for whom the concept of preemptive HSCT is discussed. Illustrated by 3 representative clinical vignettes showing specific features of MDS and AML in FA patients, this paper summarizes our practical approach from diagnosisthroughtreatment inthisparticular situation. © 2016 by The American Society of Hematology. Source

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