The distribution of HLA haplotypes in the ethnic groups that make up the Brazilian Bone Marrow Volunteer Donor Registry (REDOME).

The Registries of Bone Marrow Donors around the world include more than 30 million volunteer donors from 57 different countries, and were responsible for over 17,000 hematopoietic stem cell transplants in 2016. The Brazilian Bone Marrow Volunteer Donor Registry (REDOME) was established in 1993 and is the third largest registry in the world with more than 4.3 million donors. We characterized HLA allele and haplotypes frequencies from REDOME comparing them with the donor self-reported race group classification. Five-locus haplotype frequencies (A~C~B~DRB1~DQB1) were estimated for each of the six race groups, resolving phase and allelic ambiguity using the expectation-maximization (EM) algorithm. The top 100 haplotypes in the race groups were separated into eight clusters of haplotypes, based on haplotype similarity, using CLUTO. We present HLA allele and haplotype frequency data from six race groups from 2,938,259 individuals from REDOME. The most frequent haplotype was the same for all groups: A*01:01g~C*07:01g~B*08:01g~DRB1*03:01g~DQB1*02:01g. Some frequent haplotypes such as A*02:01g~C*16:01g~B*44:03~DRB1*07:01g~DQB1*02:01g was not found in people with Preta (Sub-Saharan African descent). A cluster including Branca (European) and Parda or non-informed (admixed) could be distinguished from both Preta (SubSaharan) and Indígena (Amerindian) groups, and from the Amarela (Asian) ones, which clustered with their original population. These results have implications on cross-population matching and can help in donor searches and population-based recruitment strategies.

Haploidentical Bone Marrow Transplantation with Post-Transplant Cyclophosphamide for Children and Adolescents with Fanconi Anemia.

We describe haploidentical bone marrow transplantation with post-transplant cyclophosphamide (PT-CY) for 30 patients with Fanconi anemia (FA). Twenty-six patients were transplanted upfront, and the preparatory regimens included fludarabine 150 mg/m2 + total body irradiation 200 to 300 cGy ± CY 10 mg/kg without (n = 12) or with rabbit antithymocyte globulin (r-ATG) 4 to 5 mg/kg (n = 14). Four patients were rescued after primary or secondary graft failure after related or unrelated donor transplantation with the above regimen with (n = 2) or without r-ATG (n = 2). PT-CY at 25 mg/kg/day (total dose, 50 mg/kg) followed by cyclosporine and mycophenolate mofetil was given to all patients. All patients engrafted in the subgroup of patients who did not receive r-ATG (n = 14), but their transplant course was complicated by high rates of acute and chronic graft-versus-host disease (GVHD), and only 8 patients are alive. In the subgroup that received r-ATG (n = 16), 14 patients had sustained engraftment, severe GVHD rates were lower, and 13 patients are alive. Hemorrhagic cystitis occurred in 50% of patients, whereas cytomegalovirus reactivation occurred in 75%. One-year overall survival for the entire cohort was 73% (95% CI, 64% to 81%), and all surviving patients achieved full donor chimerism. In conclusion, haploidentical donor transplantation with PT-CY is a suitable option for FA patients without a matched related or unrelated donor.

Long-term Survival, Organ Function, and Malignancy after Hematopoietic Stem Cell Transplantation for Fanconi Anemia.

We report on long-term survival in 157 patients with Fanconi anemia (FA) who survived 2 years or longer after their first transplantation with a median follow-up of 9 years. Marrow failure (80%) was the most common indication for transplantation. There were 20 deaths beyond 2 years after transplantation, with 12 of the deaths occurring beyond 5 years after transplantation. Donor chimerism was available for 149 patients: 112 (76%) reported > 95% chimerism, 27 (18%) reported 90% to 95% chimerism, and 8 (5%) reported 20% to 89% donor chimerism. Two patients have < 20% donor chimerism. The 10- and 15-year probabilities of survival were 90% and 79%, respectively. Results of multivariate analysis showed higher mortality risks for transplantations before 2003 (hazard ratio [HR], 7.87; P = .001), chronic graft-versus-host disease (GVHD) (HR, 3.80; P = .004) and squamous cell carcinoma after transplantation (HR, 38.17; P < .0001). The predominant cause of late mortality was squamous cell carcinoma, with an incidence of 8% and 14% at 10 and 15 years after transplantation, respectively, and was more likely to occur in those with chronic GVHD. Other causes of late mortality included chronic GVHD, infection, graft failure, other cancers, and hemorrhage. Although most patients are disease free and functional long term, our data support aggressive surveillance for long periods to identify those at risk for late mortality.

Multicenter analyses demonstrate significant clinical effects of minor histocompatibility antigens on GvHD and GvL after HLA-matched related and unrelated hematopoietic stem cell transplantation.

The effect of minor H antigen mismatching on the occurrence of graft-versus-host disease (GvHD) and graft-versus-leukemia (GvL) after HLA-matched hematopoietic stem cell transplantation (HSCT) has mainly been demonstrated in single-center studies. Yet, the International Histocompatibility and Immunogenetics Workshops (IHIW) provide a collaborative platform to execute crucial large studies. In collaboration with 20 laboratories of the IHIW, the roles of 10 autosomal and 10 Y chromosome-encoded minor H antigens were investigated on GvHD and relapse incidence in 639 HLA-identical related donor (IRD) and 210 HLA-matched unrelated donor (MUD) HSCT recipients. Donor and recipient DNA samples were genotyped for the minor H antigens HA-1, HA-2, HA-3, HA-8, HB-1, ACC-1, ACC-2, SP110, PANE1, UGT2B17, and HY. The correlations with the primary outcomes GvHD (acute or chronic GvHD), survival, and relapse were statistically analyzed. The results of these multicenter analyses show that none of the HLA class I-restricted HY antigens were found to be associated with any of the primary outcomes. Interestingly, of the HLA class II-restricted HY antigens analyzed, HLA-DQ5 positive recipients showed a significantly increased GvHD-free survival in female-to-male HSCT compared with male-to-female HSCT (P = .013). Yet, analysis of the overall gender effect, thus independent of the known HY antigens, between the gender groups demonstrated an increased GvHD incidence in the female-to-male transplantations (P < .005) and a decreased GvHD-free survival in the female-to-male transplantations (P < .001). Of all autosomally encoded minor H antigens, only mismatching for the broadly expressed minor H antigen HA-8 increased the GvHD incidence in IRD HSCT (Hazard ratio [HR] = 5.28, P < .005), but not in MUD HSCT. Most striking was the influence of hematopoietic restricted minor H antigens on GvL as mismatching for hematopoietic minor H antigens correlated with lower relapse rates (P = .078), higher relapse-free survival (P = .029), and higher overall survival (P = .032) in recipients with GvHD, but not in those without GvHD. In conclusion, the significant GvHD effect of the broadly expressed minor H antigen HA-8 favors matching for HA-8 in IRD, but not in MUD, patient/donor pairs. The GvHD-GvL association demonstrating a significant lower relapse in hematopoietic minor H antigen mismatched patient/donor pairs underlines their clinical applicability for adoptive immunotherapy, enhancing the GvL effect in a GvHD controllable manner.

Investigation of mutations in Fanconi anemia genes and malignancy predisposition in Brazilian patients.

INTRODUCTION: This study proposed to identify Fanconi anemia (FA) mutations in Brazilian patients and to investigate their impact on clinical manifestations and malignancies onset. METHODS: A total of 116 patients were screened for nine mutations in FANCA, FANCC, FANCG. Those with no mutations were investigated by multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing for FANCA, FANCC, FANCE, FANCF, FANCG, FANCD1/BRCA2. RESULTS: Genetic subtype was identified in 107/116 (78 FA-A, 8 FA-C, 13 FA-G, 8 FA-E), with only one mutation in 1/116, and no mutations in 9/116 patients. Before hematopoietic cell transplantation (HCT), malignancies were detected in 16/116 patients (14/78 FA-A, 01/08 FA-C, 01/08 FA-E), and 12 of them were hematological. Observed to expected ratio (O/E) of hematologic malignancy was 303.7 (95% CI = 148.6-458.7). CONCLUSION: This study allowed the identification of biallelic mutations in 91.4% of patients. FANCG and FANCC mutations had significantly earlier bone marrow failure onset, and FANCG severe cytopenia at diagnosis. Despite the inherent limitations of the small number of malignancy events in each genetic subtype, the hematologic malignancies O/E ratio was very high. Cumulative incidence of malignancy before HCT was higher in the third and fourth decades of life, considering HCT and death as competing risks. The cumulative incidence of HCT increased during the first decade, competing with malignancy development.

Donor-Specific HLA Antibodies Are Associated with Graft Failure and Delayed Hematologic Recovery after Unrelated Donor Hematopoietic Cell Transplantation.

Graft failure (GF) is one of the major concerns after allogeneic hematopoietic cell transplantation (allo-HCT) and remains a significant cause of morbidity and mortality. Although previous reports have associated the presence of donor-specific HLA antibodies (DSAs) with an increased risk of GF after unrelated donor allo-HCT, recent studies have failed to confirm this association. We sought to validate the presence of DSAs as a risk factor for GF and hematologic recovery in the unrelated donor allo-HCT setting. We retrospectively evaluated 303 consecutive patients who underwent their first unrelated donor allo-HCT at our institution between January 2008 and December 2017. DSA evaluation was performed using 2 single antigen bead (SAB) assays; DSA titration with 1:2, 1:8, and 1:32 dilutions; C1q-binding assay; and absorption/elution protocol to assess possible false-positive DSA reactivity. The primary endpoints were neutrophil and platelet recovery and GF, and the secondary endpoint was overall survival. Multivariable analyses were performed using Fine-Gray competing risks regression and Cox proportional hazards regression models. The median patient age was 14 years (range, 0 to 61 years), 56.1% were male, and 52.5% underwent allo-HCT for nonmalignant disease, Eleven patients (3.63%) were DSA-positive, including 10 with preexisting DSAs and 1 with post-transplantation de novo DSAs. Nine patients had 1 DSA, 1 patient had 2 DSAs, and 1 patient had 3 DSAs, with a median mean fluorescent intensity (MFI) of 4334 (range, 588 to 20,456) and 3581 (range, 227 to 12,266) in LABScreen and LIFECODES SAB assays, respectively. Overall, 21 patients experienced GF, including 12 with primary graft rejection, 8 with secondary graft rejection, and 1 with primary poor graft function. The cumulative incidence of GF was 4.0% (95% confidence interval [CI], 2.2% to 6.6%) at 28 days, 6.6% (95% CI, 4.2% to 9.8%) at 100 days, and 6.9% (95% CI, 4.4% to 10.2%) at 365 days. In the multivariable analyses, DSA-positive patients had significantly delayed neutrophil recovery (subdistribution hazard ratio [SHR], .48; 95% CI, .29 to .81; P = .006) and platelet recovery (SHR, .51; 95% CI, .35 to .74; P = .0003) compared to patients without DSAs. In addition, only DSAs were significant predictors of primary GF at 28 days (SHR, 2.78; 95% CI, 1.65 to 4.68; P = .0001). The Fine-Gray regression also demonstrated that the presence of DSAs was strongly associated with a higher incidence of overall GF (SHR, 7.60; 95% CI, 2.61 to 22.14; P = .0002). DSA-positive patients with GF had significantly higher median MFI values than DSA-positive patients who achieved engraftment in the LIFECODES SAB assay using neat serum (10,334 versus 1250; P = .006) and in the LABScreen SAB at 1:32 dilution (1627 versus 61; P = .006). All 3 patients with C1q-positive DSAs failed to engraft. DSAs were not predictive of inferior survival (HR, .50; 95% CI, .20 to 1.26; P = .14). Our results validate the presence of DSAs as a significant risk factor for GF and delayed hematologic recovery after unrelated donor allo-HCT. Careful pretransplantation DSA evaluation may optimize unrelated donor selection and improve allo-HCT outcomes.

Untreated Donor-Specific HLA Antibodies Are Associated With Graft Failure and Poor Survival After Haploidentical Transplantation With Post-Transplantation Cyclophosphamide in Pediatric Patients With Nonmalignant Disorders.

Donor-specific HLA antibodies (DSAs) have been recognized as a major risk factor for graft failure (GF) in adult patients with malignancies undergoing haploidentical transplantation with post-transplantation cyclophosphamide (haplo-PTCy). However, the impact of DSAs after pediatric haplo-PTCy for nonmalignant disorders (NMDs) has been poorly reported. We sought to investigate whether preexisting DSAs adversely affect pediatric haplo-PTCy outcomes. We retrospectively analyzed 59 pediatric patients (≤21 years) who received their first haplo-PTCy for NMDs from January 2008 to December 2017. DSA testing was performed using single antigen beads, and mean fluorescence intensity (MFI) >1000 was considered positive, and MFI <1000 and >500 was considered potentially positive, based on HLA epitope reactivity patterns. Primary endpoints were neutrophil and platelet recovery and GF, whereas secondary endpoints included event-free and overall survival. Multivariable analyses were performed using Fine-Gray competing risk regression or Cox proportional hazards regression models. The median age was 10 years, and 66.1% were male. Main indications for haplo-PTCy were Fanconi anemia (n = 33) and severe aplastic anemia (n = 11). All patients received bone marrow as the graft source, and most patients (91.5%) received fludarabine-based conditioning. Overall, 15 patients (25.4%) had DSAs >500 MFI. Four patients had false-positive DSAs with median MFI of 1762. Of the 11 patients with true-positive DSA reactivity, 5 had 1 DSA, 5 had 2 DSAs, and 1 had 3 DSAs, with median MFI of 2372 (range 527-24,200). Four patients received desensitization therapy with rituximab and plasmapheresis, whereas 7 patients were untreated. All patients with treated DSAs achieved donor engraftment. In the multivariable analyses, untreated DSAs were associated with lower neutrophil recovery (subdistribution hazard ratio [SHR] = 0.15; 95% confidence interval [CI], 0.03-0.63; P = .001), increased GF (SHR = 20.57; 95% CI, 6.57-64.43; P < .001), inferior event-free survival (hazard ratio [HR] = 10.09; 95% CI, 3.37-30.22; P < .001), and poor overall survival (HR 5.56; 95% CI, 1.92-16.12; P = .002). Both treated DSAs (SHR = 0.26; 95% CI, 0.10-0.68; P = .006) and untreated DSAs (SHR = 0.13; 95% CI, 0.04-0.37; P < .001) adversely affected platelet recovery. Our results indicate that the presence of DSAs is an independent predictor of poor outcomes after pediatric haplo-PTCy for NMDs. Therefore DSA-positive donors should be avoided whenever possible, and when a DSA-negative donor is unavailable, desensitization therapy must be performed to enhance the likelihood of donor engraftment and improve transplantation outcomes.

TLR8-dependent TNF-(alpha) overexpression in Fanconi anemia group C cells.

Tumor necrosis factor alpha (TNF-alpha) production is abnormally high in Fanconi anemia (FA) cells and contributes to the hematopoietic defects seen in FA complementation group C-deficient (Fancc(-/-)) mice. Applying gene expression microarray and proteomic methods to studies on FANCC-deficient cells we found that genes encoding proteins directly involved in ubiquitinylation are overrepresented in the signature of FA bone marrow cells and that ubiquitinylation profiles of FA-C and complemented cells were substantially different. Finding that Toll-like receptor 8 (TLR8) was one of the proteins ubiquitinylated only in mutant cells, we confirmed that TLR8 (or a TLR8-associated protein) is ubiquitinylated in mutant FA-C cells and that TNF-alpha production in mutant cells depended upon TLR8 and the canonical downstream signaling intermediates interleukin 1 receptor-associated kinase (IRAK) and IkappaB kinase-alpha/beta. FANCC-deficient THP-1 cells and macrophages from Fancc(-/-) mice overexpressed TNF-alpha in response to TLR8 agonists but not other TLR agonists. Ectopically expressed FANCC point mutants were capable of fully complementing the mitomycin-C hypersensitivity phenotype of FA-C cells but did not suppress TNF-alpha overproduction. In conclusion, FANCC suppresses TNF-alpha production in mononuclear phagocytes by suppressing TLR8 activity and this particular function of FANCC is independent of its function in protecting the genome from cross-linking agents.

The impact of donor-specific anti-human leukocyte antigen antibodies in salvage haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide in patients with nonmalignant disorders.

The presence of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) has been recognized as a major risk factor for graft failure (GF) after haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide (haplo-PTCy). However, the role of DSAs in salvage haplo-PTCy for rescuing patients with nonmalignant disorders (NMDs) has not yet been reported. The present study retrospectively analyzed 22 patients with NMDs who underwent salvage haplo-PTCy from January 2008 to December 2017. The median age at the time of the rescue haplo-PTCy was 9 years (range, 1-26 years). Median time from the first transplant to second haplo-PTCy was 56 days (range, 37-591 days). Among all patients, six (27.3%) had DSAs, with a median DSA strength (mean fluorescence intensity [MFI]) of 5201 (range, 1412-11,543) in the first DSA testing. In addition, the median DSA MFI was 2672 (range, 832-10,498) before the bone marrow infusion. Overall, GF occurred in 5 (25%) of the 20 assessable patients. Three of four (75%) patients with DSAs experienced GF versus 2 of 16 (12.5%) DSA-negative patients (P = 0.032). The median DSA MFI for patients with GF was 6437 (range, 1412-10,498) versus 1845 (range, 832-2672) for those who engrafted or had early death (P = 0.030). One-year event-free survival was significantly lower in DSA-positive patients than in those without DSAs (16.7% vs. 62.5%, P = 0.002). DSA-negative patients had an acceptable 1-year survival of 62.5%. In conclusion, this study suggests that DSAs may be associated with deleterious outcomes after salvage haplo-PTCy in patients with NMDs.

Phenotype frequencies of autosomal minor histocompatibility antigens display significant differences among populations.

Minor histocompatibility (H) antigens are allogeneic target molecules having significant roles in alloimmune responses after human leukocyte antigen-matched solid organ and stem cell transplantation (SCT). Minor H antigens are instrumental in the processes of transplant rejection, graft-versus-host disease, and in the curative graft-versus-tumor effect of SCT. The latter characteristic enabled the current application of selected minor H antigens in clinical immunotherapeutic SCT protocols. No information exists on the global phenotypic distribution of the currently identified minor H antigens. Therefore, an estimation of their overall impact in human leukocyte antigen-matched solid organ and SCT in the major ethnic populations is still lacking. For the first time, a worldwide phenotype frequency analysis of ten autosomal minor H antigens was executed by 31 laboratories and comprised 2,685 randomly selected individuals from six major ethnic populations. Significant differences in minor H antigen frequencies were observed between the ethnic populations, some of which appeared to be geographically correlated.

Investigation of MHC gamma block C4A and C4B polymorphisms in unrelated hematopoietic stem cell transplantation.

BACKGROUND: Immunological life-threatening complications frequently occur in post-hematopoietic stem cell transplantation (HSCT), despite matching recipient and donor (R/D) pairs for classical human leukocyte antigens (HLA). Studies have shown that R/D non-HLA disparities within the major histocompatibility complex (MHC) are associated with adverse effects post-HSCT. METHODS: We investigated the impact of mismatches of single-nucleotide polymorphisms (SNPs) in C4A/C4B genes, for showing the highest diversity in the MHC gamma block, on 238 patients who underwent HLA 10/10 unrelated donor (URD) HSCT. The endpoints were acute graft-versus-host disease (aGVHD), chronic graft-versus-host disease (cGVHD) and mortality. One hundred and twenty-nine R/D pairs had 23 C4-SNPs typed by PCR-SSP (Gamma-Type™v.1.0), and 109 R/D pairs had these 23 SNPs identified by next-generation sequencing (NGS) using the Illumina platform. RESULTS: The percentage of patients who received HSC from HLA 10/10 donors with 1-7 mismatches was 42.9%. The R/D pairs were considered C4mismatched when bearing at least one disparity. These mismatches were not found to be risk factors for aGVHD, cGVHD or mortality after unrelated HSCT when SNPs were analyzed together (matched or mm≥1), independently or according to the percentage of incompatibilities (full match for 23 SNPs; 1-3mm and >3mm). An exception was the association between 1-3 mismatches at the composite of SNPs C13193/T14952/T19588 with the development of aGVHD (P=0.012) and with grades III-IV of this disease (P=0.004). CONCLUSION: Our data are not consistent with the hypothesis that disparities in C4A/C4B SNPs increase the risks of post-HSCT adverse effects for the endpoints investigated in this study.

Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene in Brazilian patients with chronic myeloid leukemia.

INTRODUCTION: Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene are the leading cause of resistance to treatment with tyrosine kinase inhibitors in chronic myeloid leukemia patients. Mutations have been detected throughout the extension of the kinase domain of this gene and it is important to investigate their positions because there may be a difference in clinical relevance. OBJECTIVE: To evaluate mutations in the transcripts of the BCR-ABL1 gene in Brazilian patients with chronic myeloid leukemia under tyrosine kinase inhibitor treatment in the Hospital de Clínicas of the Universidade Federal do Paraná. METHODS: This retrospective observational cross-sectional study analyzed mutation data of BCR-ABL1 gene transcripts. Three hundred and thirty peripheral blood samples from 193 patients were evaluated with the search for mutations being achieved by Sanger sequencing. RESULTS: Sixteen mutation types were identified in 48/193 (24.87%) patients with T315I (20.83%) being the most common. Furthermore, four polymorphisms (T240T, K247R, E275E and Y275Y) were identified. The highest incidence of mutations (19/53: 35.85%) occurred in the P-loop of the tyrosine kinase domain, whereas no mutation was found in the A-loop. In 43/48 (89.58%) patients only one mutation was found and more than one mutation was found in 5/48 (10.42%). The simultaneous presence of two mutations (E189G/V299L and E255K/T315I) was observed in 2/5 patients while the different mutations were seen in sequential samples of the other three patients (Y253Y/T315I, T315I/E255K and E255K/T315I). CONCLUSIONS: This molecular characterization contributed to the identification of the resistance profile to tyrosine kinase inhibitors in Brazilian patients, thus enabling the use of adequate therapeutic strategies in a timely manner.

Late chimerical status after bone marrow transplantation in severe aplastic anemia according to two different preparatory regimens.

BACKGROUND: This study investigated the influence of two conditioning regimens on the chimerical status of 104 patients with acquired severe aplastic anemia. METHODS: Patients were monitored for at least 18 months after related bone marrow transplantation and reaching partial or complete hematologic recovery. Group I patients (n = 55) received 200 mg/kg cyclophosphamide alone and Group II (n = 49) received 120 mg/kg cyclophosphamide associated with 12 mg/kg busulfan. Patients were classified in three chimerism levels according to the percentage of donor cells in the peripheral blood. RESULTS: Chimerism ≤50% occurred in 36.4% of Group I and none of Group II; chimerism 51-90% was found in 20.0% of Group I and 10.2% of Group II; and chimerism >90% was found in 43.6% of Group I versus 89.8% of Group II. A significant association (p-value < 0.001) was found between conditioning type and chimerism levels. A higher number of infused cells was associated with higher levels of chimerism only in Group I (p-value = 0.013). Multivariate analysis showed that chimerism >90% is associated with the cyclophosphamide plus busulfan conditioning (p-value < 0.001) and higher number of infused cells (p-value = 0.009), suggesting that these factors are predictive of graft outcome. Regarding hematological recovery, higher chimerism levels were associated with higher neutrophil (p-value = 0.003) and platelet counts (p-value < 0.001) in Group I only. These results show that myeloablative conditioning favors full donor chimerism and non-myeloablative conditioning predisposes to mixed chimerism or autologous recovery of hematopoiesis. CONCLUSION: These data show that autologous recovery depends on the intensity of immunosuppression and that the immunosuppressive function of cyclophosphamide alone can induce this type of hematopoietic recovery.

Molecular response to imatinib mesylate of Brazilian patients with chronic myeloid leukemia.

BACKGROUND: Imatinib mesylate has revolutionized the treatment of chronic myeloid leukemia leading to significant reductions of BCR-ABL1 transcript levels in peripheral blood. OBJECTIVE: To evaluate the response to imatinib mesylate treatment (400mg/day) in Brazilian patients in the chronic phase of chronic myeloid leukemia monitored by quantitative real time polymerase chain reaction. METHODS: Between October 2002 and October 2010, 3169 peripheral blood samples were collected from 1403 patients from 3 to 5 months, 6 to 11 months, 12 to 17 months, 18 to 23 months and ≥24 months after beginning imatinib treatment. Eighty-two patients had samples available and analyzed for all time intervals. BCR-ABL1 quantification was performed by quantitative real time polymerase chain reaction using the ABL1 gene as the control. Results of the BCR-ABL1 ratio as a percentage were reported by the international scale (IS) using the laboratory conversion factor (0.51). RESULTS: In the first interval, 80.8% of patients achieved the optimal response (BCR-ABL1IS≤10%). In the second period, 69.1% achieved optimal response (BCR-ABL1IS≤1%) and, between 12 and 17 months, 47.3% achieved major molecular response (BCR-ABL1IS≤0.1%). CONCLUSIONS: The results of this retrospective study show that the response to imatinib treatment (400mg/day) of Brazilian patients in the chronic phase of chronic myeloid leukemia is within the expected profile when compared to patients reported in international prospective randomized studies.

A strategy for molecular diagnostics of Fanconi anemia in Brazilian patients.

BACKGROUND: Fanconi anemia (FA) is a predominantly autosomal recessive disease with wide genetic heterogeneity resulting from mutations in several DNA repair pathway genes. To date, 21 genetic subtypes have been identified. We aimed to identify the FA genetic subtypes in the Brazilian population and to develop a strategy for molecular diagnosis applicable to routine clinical use. METHODS: We screened 255 patients from Hospital de Clínicas, Universidade Federal do Paraná for 11 common FA gene mutations. Further analysis by multiplex ligation-dependent probe amplification (MLPA) for FANCA and Sanger sequencing of all coding exons of FANCA, -C, and -G was performed in cases who harbored a single gene mutation. RESULTS: We identified biallelic mutations in 128/255 patients (50.2%): 89, 11, and 28 carried FANCA,FANCC, and FANCG mutations, respectively. Of these, 71 harbored homozygous mutations, whereas 57 had compound heterozygous mutations. In 4/57 heterozygous patients, both mutations were identified by the initial screening, in 51/57 additional analyses was required for classification, and in 2/57 the second mutation remained unidentified. We found 52 different mutations of which 22 were novel. CONCLUSION: The proposed method allowed genetic subtyping of 126/255 (49.4%) patients at a significantly reduced time and cost, which makes molecular diagnosis of FA Brazilian patients feasible.

Investigation of MHC gamma block C4A and C4B polymorphisms in unrelated hematopoietic stem cell transplantation

ABSTRACT Background: Immunological life-threatening complications frequently occur in post-hematopoietic stem cell transplantation (HSCT), despite matching recipient and donor (R/D) pairs for classical human leukocyte antigens (HLA). Studies have shown that R/D non-HLA disparities within the major histocompatibility complex (MHC) are associated with adverse effects post-HSCT. Methods: We investigated the impact of mismatches of single-nucleotide polymorphisms (SNPs) in C4A/C4B genes, for showing the highest diversity in the MHC gamma block, on 238 patients who underwent HLA 10/10 unrelated donor (URD) HSCT. The endpoints were acute graft-versus-host disease (aGVHD), chronic graft-versus-host disease (cGVHD) and mortality. One hundred and twenty-nine R/D pairs had 23 C4-SNPs typed by PCR-SSP (Gamma-Type™v.1.0), and 109 R/D pairs had these 23 SNPs identified by next-generation sequencing (NGS) using the Illumina platform. Results: The percentage of patients who received HSC from HLA 10/10 donors with 1-7 mismatches was 42.9%. The R/D pairs were considered C4 mismatched when bearing at least one disparity. These mismatches were not found to be risk factors for aGVHD, cGVHD or mortality after unrelated HSCT when SNPs were analyzed together (matched or mm ≥ 1), independently or according to the percentage of incompatibilities (full match for 23 SNPs; 1-3 mm and >3 mm). An exception was the association between 1-3 mismatches at the composite of SNPs C13193/T14952/T19588 with the development of aGVHD (P = 0.012) and with grades III-IV of this disease (P = 0.004). Conclusion: Our data are not consistent with the hypothesis that disparities in C4A/C4B SNPs increase the risks of post-HSCT adverse effects for the endpoints investigated in this study.

Late chimerical status after bone marrow transplantation in severe aplastic anemia according to two different preparatory regimens

ABSTRACT Background: This study investigated the influence of two conditioning regimens on the chimerical status of 104 patients with acquired severe aplastic anemia. Methods: Patients were monitored for at least 18 months after related bone marrow transplantation and reaching partial or complete hematologic recovery. Group I patients (n = 55) received 200 mg/kg cyclophosphamide alone and Group II (n = 49) received 120 mg/kg cyclophosphamide associated with 12 mg/kg busulfan. Patients were classified in three chimerism levels according to the percentage of donor cells in the peripheral blood. Results: Chimerism ≤50% occurred in 36.4% of Group I and none of Group II; chimerism 51-90% was found in 20.0% of Group I and 10.2% of Group II; and chimerism >90% was found in 43.6% of Group I versus 89.8% of Group II. A significant association (p-value < 0.001) was found between conditioning type and chimerism levels. A higher number of infused cells was associated with higher levels of chimerism only in Group I (p-value = 0.013). Multivariate analysis showed that chimerism >90% is associated with the cyclophosphamide plus busulfan conditioning (p-value < 0.001) and higher number of infused cells (p-value = 0.009), suggesting that these factors are predictive of graft outcome. Regarding hematological recovery, higher chimerism levels were associated with higher neutrophil (p-value = 0.003) and platelet counts (p-value < 0.001) in Group I only. These results show that myeloablative conditioning favors full donor chimerism and non-myeloablative conditioning predisposes to mixed chimerism or autologous recovery of hematopoiesis. Conclusion: These data show that autologous recovery depends on the intensity of immunosuppression and that the immunosuppressive function of cyclophosphamide alone can induce this type of hematopoietic recovery.

Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene in Brazilian patients with chronic myeloid leukemia

ABSTRACT Introduction: Mutations in the breakpoint cluster region-Abelson murine leukemia 1 gene are the leading cause of resistance to treatment with tyrosine kinase inhibitors in chronic myeloid leukemia patients. Mutations have been detected throughout the extension of the kinase domain of this gene and it is important to investigate their positions because there may be a difference in clinical relevance. Objective: To evaluate mutations in the transcripts of the BCR-ABL1 gene in Brazilian patients with chronic myeloid leukemia under tyrosine kinase inhibitor treatment in the Hospital de Clínicas of the Universidade Federal do Paraná. Methods: This retrospective observational cross-sectional study analyzed mutation data of BCR-ABL1 gene transcripts. Three hundred and thirty peripheral blood samples from 193 patients were evaluated with the search for mutations being achieved by Sanger sequencing. Results: Sixteen mutation types were identified in 48/193 (24.87%) patients with T315I (20.83%) being the most common. Furthermore, four polymorphisms (T240T, K247R, E275E and Y275Y) were identified. The highest incidence of mutations (19/53: 35.85%) occurred in the P-loop of the tyrosine kinase domain, whereas no mutation was found in the A-loop. In 43/48 (89.58%) patients only one mutation was found and more than one mutation was found in 5/48 (10.42%). The simultaneous presence of two mutations (E189G/V299L and E255K/T315I) was observed in 2/5 patients while the different mutations were seen in sequential samples of the other three patients (Y253Y/T315I, T315I/E255K and E255K/T315I). Conclusions: This molecular characterization contributed to the identification of the resistance profile to tyrosine kinase inhibitors in Brazilian patients, thus enabling the use of adequate therapeutic strategies in a timely manner.

Molecular response to imatinib mesylate of Brazilian patients with chronic myeloid leukemia

Abstract Background Imatinib mesylate has revolutionized the treatment of chronic myeloid leukemia leading to significant reductions of BCR-ABL1 transcript levels in peripheral blood. Objective To evaluate the response to imatinib mesylate treatment (400 mg/day) in Brazilian patients in the chronic phase of chronic myeloid leukemia monitored by quantitative real time polymerase chain reaction. Methods Between October 2002 and October 2010, 3169 peripheral blood samples were collected from 1403 patients from 3 to 5 months, 6 to 11 months, 12 to 17 months, 18 to 23 months and ≥24 months after beginning imatinib treatment. Eighty-two patients had samples available and analyzed for all time intervals. BCR-ABL1 quantification was performed by quantitative real time polymerase chain reaction using the ABL1 gene as the control. Results of the BCR-ABL1 ratio as a percentage were reported by the international scale (IS) using the laboratory conversion factor (0.51). Results In the first interval, 80.8% of patients achieved the optimal response (BCR-ABL1 IS ≤ 10%). In the second period, 69.1% achieved optimal response (BCR-ABL1 IS ≤ 1%) and, between 12 and 17 months, 47.3% achieved major molecular response (BCR-ABL1 IS ≤ 0.1%). Conclusions The results of this retrospective study show that the response to imatinib treatment (400 mg/day) of Brazilian patients in the chronic phase of chronic myeloid leukemia is within the expected profile when compared to patients reported in international prospective randomized studies.

Activating KIR and HLA Bw4 ligands are associated to decreased susceptibility to pemphigus foliaceus, an autoimmune blistering skin disease.

The KIR genes and their HLA class I ligands have thus far not been investigated in pemphigus foliaceus (PF) and related autoimmune diseases, such as pemphigus vulgaris. We genotyped 233 patients and 204 controls for KIR by PCR-SSP. HLA typing was performed by LABType SSO reagent kits. We estimated the odds ratio, 95% confidence interval and performed logistic regression analyses to test the hypothesis that KIR genes and their known ligands influence susceptibility to PF. We found significant negative association between activating genes and PF. The activating KIR genes may have an overlapping effect in the PF susceptibility and the presence of more than three activating genes was protective (OR=0.49, p=0.003). A strong protective association was found for higher ratios activating/inhibitory KIR (OR=0.44, p=0.001). KIR3DS1 and HLA-Bw4 were negatively associated to PF either isolated or combined, but higher significance was found for the presence of both together (OR=0.34, p<10(-3)) suggesting that the activating function is the major factor to interfere in the PF pathogenesis. HLA-Bw4 (80I and 80T) was decreased in patients. There is evidence that HLA-Bw4(80T) may also be important as KIR3DS1 ligand, being the association of this pair (OR=0.07, p=0.001) stronger than KIR3DS1-Bw4(80I) (OR=0.31, p=0.002). Higher levels of activating KIR signals appeared protective to PF. The activating KIR genes have been commonly reported to increase the risk for autoimmunity, but particularities of endemic PF, like the well documented influence the environmental exposure in the pathogenesis of this disease, may be the reason why activated NK cells probably protect against pemphigus foliaceus.