Intravenous busulfan is widely used as part of myeloablative conditioning regimens in children and young adults undergoing allogeneic hematopoietic cell transplantation (HCT). Hepatic veno... Show moreIntravenous busulfan is widely used as part of myeloablative conditioning regimens in children and young adults undergoing allogeneic hematopoietic cell transplantation (HCT). Hepatic veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a serious clinical problem observed with busulfan-based conditioning HCT. The development of VOD/SOS may be associated with busulfan exposure. Getting more insight into the association between busulfan exposure and the development of VOD/SOS enables further optimization of dos-ing and treatment strategies. The objective of this study was to assess the association between the magnitude of busulfan exposure and the occurrence of VOD/SOS in children and young adults undergoing myeloablative con-ditioning with a busulfan-containing regimen before allogeneic HCT. In this observational study we included all patients who underwent allogeneic HCT with intravenous busulfan as part of the conditioning regimen at 15 pediatric transplantation centers between 2000 and 2015. The endpoint was the development of VOD/SOS. The magnitude of busulfan exposure was estimated using nonlinear mixed effect modeling and expressed as the maximal concentration (Cmax; day 1 and day 1 to 4 Cmax), cumulative area under the curve (AUC; day 1, high-est 1-day AUC in 4 days, and 4-day cumulative AUC), cumulative time above a concentration of 300 mg/L, and clearance on day 1. A total of 88 out of 697 patients (12.6%) developed VOD/SOS. The number of alkylators in the conditioning regimen was a strong effect modifier; therefore we stratified the regression analysis for the number of alkylators. For patients receiving only busulfan as one alkylator (36.3%, n = 253), cumulative busulfan exposure (>78 mg x h/L) was associated with increased VOD/SOS risk (12.6% versus 4.7%; odds ratio [OR] = 2.95, 95% confidence interval [CI] 1.13 to 7.66). For individuals receiving busulfan with one or two addi-tional alkylators (63.7%, n = 444), cumulative busulfan exposure (<78 and >78 mg x h/L) did not further increase the risk of VOD/SOS (15.4% versus 15.2%; OR = 1.03, 95% CI 0.61 to 1.75). The effect of the magnitude of busulfan exposure on VOD/SOS risk in children and young adults undergoing HCT is dependent on the number of alkylators. In patients receiving busulfan as the only alkylator, higher cumulative busulfan exposure increased the risk of VOD/SOS, whereas in those receiving multiple alkylators, the magnitude of busulfan expo-sure did not further increase this risk. Show less
Acute Graft versus Host Disease (aGvHD) grades 2-4 occurs in 15-60% of pediatric patients undergoing allogeneic haematopoietic stem-cell transplantation (allo-HSCT). The collateral damage to normal... Show moreAcute Graft versus Host Disease (aGvHD) grades 2-4 occurs in 15-60% of pediatric patients undergoing allogeneic haematopoietic stem-cell transplantation (allo-HSCT). The collateral damage to normal tissue by conditioning regimens administered prior to allo-HSCT serve as an initial trigger for aGvHD. DNA-repair mechanisms may play an important role in mitigating this initial damage, and so the variants in corresponding DNA-repair protein-coding genes via affecting their quantity and/or function. We explored 51 variants within 17 DNA-repair genes for their association with aGvHD grades 2-4 in 60 pediatric patients. The cumulative incidence of aGvHD 2-4 was 12% (n = 7) in the exploratory cohort. MGMT rs10764881 (G>A) and EXO rs9350 (c.2270C>T) variants were associated with aGvHD 2-4 [Odds ratios = 14.8 (0 events out of 40 in rs10764881 GG group) and 11.5 (95% CI: 2.3-191.8), respectively, multiple testing corrected p <= 0.001]. Upon evaluation in an extended cohort (n = 182) with an incidence of aGvHD 2-4 of 22% (n = 40), only MGMT rs10764881 (G>A) remained significant (adjusted HR = 2.05 [95% CI: 1.06-3.94]; p = 0.03) in the presence of other clinical risk factors. Higher MGMT expression was seen in GG carriers for rs10764881 and was associated with higher IC50 of Busulfan in lymphoblastoid cells. MGMT rs10764881 carrier status could predict aGvHD occurrence in pediatric patients undergoing allo-HSCT. Show less
Purpose This study aimed to retrospectively evaluate the genetic association of null variants of glutathione S-transferases GSTM1 and GSTT1 with relapse incidence in children with hematological... Show morePurpose This study aimed to retrospectively evaluate the genetic association of null variants of glutathione S-transferases GSTM1 and GSTT1 with relapse incidence in children with hematological malignancies (HMs) undergoing busulfan (BU)- containing allogeneic hematopoietic stem cell transplantation (HSCT) and to assess the impact of these variants on BU-induced cytotoxicity on the immortalized lymphoblastoid cell lines (LCLs) and tumor THP1 GST gene-edited cell models. Methods GSTM1- and GSTT1-null alleles were genotyped using germline DNA from whole blood prior to a conditioning BU-based regimen. Association of GSTM1- and GSTT1-null variants with relapse incidence was analyzed using multivariable competing risk analysis. BU-induced cell death studies were conducted in GSTs- null and non-null LCLs and CRISPR-Cas9 gene-edited THP1 leukemia cell lines. Results Carrying GSTM1/GSTT1 double null genotype was found to be an independent risk factor for post-HSCT relapse in 86 children (adjusted HR: 6.52 [95% Cl, 2.76-15.42; p = 1.9 x 10(-5)]). BU-induced cell death preferentially in THP1(GSTM1(non-null)) and LCLs(GSTM1(non-null)) as shown by decreased viability, increased necrosis and levels of the oxidized form of glutathione compared to null cells, while GSTT1 non-null cells showed increased baseline proliferation. Conclusion The clinical association suggests that GSTM1/GSTT1 double null genotype could serve as genetic stratification biomarker for the high risk of post-HSCT relapse. Functional studies have indicated that GSTM1 status modulates BU-induced cell death. On the other hand, GSTT1 is proposed to be involved in baseline cell proliferation. Show less
Hassine, K. ben; Nava, T.; Thoret, Y.; Nath, C.E.; Daali, Y.; Kassir, N.; ... ; Ansari, M. 2021
Busulfan (Bu) is a common component of conditioning regimens before hematopoietic stem cell transplantation (HSCT) and is known for high interpatient pharmacokinetic (PK) variability. This study... Show moreBusulfan (Bu) is a common component of conditioning regimens before hematopoietic stem cell transplantation (HSCT) and is known for high interpatient pharmacokinetic (PK) variability. This study aimed to develop and externally validate a multicentric, population PK (PopPK) model for intravenous Bu in pediatric patients before HSCT to first study the influence of glutathione-s-transferase A1 (GSTA1) polymorphisms on Bu's PK in a large multicentric pediatric population while accounting for fludarabine (Flu) coadministration and, second, to establish an individualized, model-based, first-dose recommendation for intravenous Bu that can be widely used in pediatric patients. The model was built using data from 302 patients from five transplantation centers who received a Bu-based conditioning regimen. External model validation used data from 100 patients. The relationship between body weight and Bu clearance (CL) was best described by an age-dependent allometric scaling of a body weight model. A stepwise covariate analysis identified Day 1 of Bu conditioning, GSTA1 metabolic groups based on GSTA1 polymorphisms, and Flu coadministration as significant covariates influencing Bu CL. The final model adequately predicted Bu first-dose CL in the external cohort, with 81% of predicted area under the curves within the therapeutic window. The final model showed minimal bias (mean prediction error, -0.5%; 95% confidence interval [CI], -3.1% to 2.0%) and acceptable precision (mean absolute prediction error percentage, 18.7%; 95% CI, 17.0%-20.5%) in Bu CL prediction for dosing. This multicentric PopPK study confirmed the influence of GSTA1 polymorphisms and Flu coadministration on Bu CL. The developed model accurately predicted Bu CL and first doses in an external cohort of pediatric patients. Show less
Ansari, M.; Petrykey, K.; Rezgui, M.A.; Vecchio, V. del; Cortyl, J.; Ameur, M.; ... ; Krajinovic, M. 2021
The most frequent complication of allogeneic hematopoietic stem cell transplantation is acute Graft versus Host Disease (aGVHD). Proliferation and differentiation of donor T cells initiate... Show moreThe most frequent complication of allogeneic hematopoietic stem cell transplantation is acute Graft versus Host Disease (aGVHD). Proliferation and differentiation of donor T cells initiate inflammatory response affecting the skin, liver, and gastrointestinal tract. Besides recipient-donor HLA disparities, disease type, and the conditioning regimen, variability in the non-HLA genotype have an impact on aGVHD onset, and genetic variability of key cytokines and chemokines was associated with increased risk of aGVHD. To get further insight into the recipient genetic component of aGVHD grades 2-4 in pediatric patients, we performed an exome-wide association study in a discovery cohort (n = 87). Nine loci sustained correction for multiple testing and were analyzed in a validation group (n = 168). Significant associations were replicated for ERC1 rs1046473, PLEK rs3816281, NOP9 rs2332320 and SPRED1 rs11634702 variants through the interaction with non-genetic factors. The ERC1 variant was significant among patients that received the transplant from HLA-matched related individuals (p = 0.03), bone marrow stem cells recipients (p = 0.007), and serotherapy-negative patients (p = 0.004). NOP9, PLEK, and SPRED1 effects were modulated by stem cell source, and serotherapy (p < 0.05). Furthermore, ERC1 and PLEK SNPs correlated with aGVHD 3-4 independently of non-genetic covariates (p = 0.02 and p = 0.003). This study provides additional insight into the genetic component of moderate to severe aGVHD. Show less
Ansari, M.; Petrykey, K.; Rezgui, M.A.; Vecchio, V. del; Cortyl, J.; Ralph, R.O.; ... ; Pediat Dis Working Party European 2020
Sinusoidal obstruction syndrome (SOS) is a well-recognized and potentially life-threatening complication of hematopoietic stem cell transplantation (HSCT). SOS arises from endothelial cell damage... Show moreSinusoidal obstruction syndrome (SOS) is a well-recognized and potentially life-threatening complication of hematopoietic stem cell transplantation (HSCT). SOS arises from endothelial cell damage and hepatocellular injury mostly due to the transplantation conditioning regimens but also to other patient, disease, and treatment-related factors. Understanding risk factors associated with the development of SOS is critical for early initiation of treatment or prophylaxis. The knowledge about genetic contribution is limited; few studies investigated so far selected a set of genes. To get more comprehensive insight in the genetic component, we performed an exome-wide association study using genetic variants derived from whole-exome sequencing. The analyses were performed in a discovery cohort composed of 87 pediatric patients undergoing HSCT following a busulfan-containing conditioning regimen. Eight lead single-nucleotide polymorphisms (SNPs) were identified after correction for multiple testing and subsequently analyzed in a validation cohort (n = 182). Three SNPs were successfully replicated, including rs17146905 ( P = .001), rs16931326 ( P = .04), and rs2289971 ( P = .03), located respectively in the UGT2B10, BHLHE22, and KIAA1715 genes. UGT2B10 and KIAA1715 were retained in a multivariable model while controlling for nongenetic covariates and previously identified risk variants in the GSTA1 promoter. The modulation of associations by conditioning regimens was noted; KIAA1715 was dependent on the intensity of the conditioning regimen, whereas the effect of UGT2B10 was equally applicable to all of them. Combined effect of associated loci was also observed ( P = .00006) with a genotype-related SOS risk of 9.8. To our knowledge, this is the first study addressing the genetic component of SOS at an exome-wide level and identifying novel genetic variations conferring a higher risk of SOS, which might be useful for personalized prevention and treatment strategies. (C) 2019 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. Show less
Ansari, M.; Curtis, P.H.D.; Uppugunduri, C.R.S.; Rezgui, M.A.; Nava, T.; Mlakar, V.; ... ; Krajinovic, M. 2017
