ABCB1 haplotype is associated with major molecular response in chronic myeloid leukemia patients treated with standard-dose of imatinib.

BACKGROUND: Imatinib mesylate (IM) is a selective tyrosine kinase inhibitor used for treating chronic myeloid leukemia (CML). IM has high efficacy, however some individuals develop a resistance due to impaired bioavailability. Polymorphisms in genes encoding membrane transporters such as ABCB1 have been associated with differences in protein expression and function that influence the response to several drugs. AIM: To investigate the relationship of ABCB1 polymorphisms with markers of response to IM in patients with CML. METHODS: One hundred eighteen CML patients initially treated with a standard dose of IM (400mg/day) for 18months were selected at two health centers in Sao Paulo City, Brazil. The response criteria were based on the European LeukemiaNet recommendations. ABCB1 polymorphisms c.1236C>T (rs1128503), c.3435C>T (rs1045642) and c.2677G>T/A (rs2032582) were evaluated by PCR-RFLP. RESULTS: ABCB1 polymorphisms were not related with a risk for CML in this sample population (p<0.05). In the CML group, frequencies of ABCB1 SNPs were similar between responder and non-responder patients (p>0.05). In the responder group, the frequency of ABCB11236CT/2677GT/3435CT haplotype was higher in patients with major molecular response (MMR) (51.7%) than in patients without MMR (8.3%, p=0.010). Furthermore, carriers of this haplotype had increased the probability of reaching the MMR compared with the non-carriers (OR: 11.8; 95% CI: 1.43-97.3, p=0.022). CONCLUSIONS: The ABCB1 1236CT/2677GT/3435CT haplotype is positively associated with the major molecular response to IM in CML patients.

Impact of Epstein-Barr virus in the clinical evolution of patients with classical Hodgkin's lymphoma in Brazil.

INTRODUCTION: Classical Hodgkin's Lymphoma (cHL) has been frequently associated with Epstein-Barr virus (EBV), which can be found in a latent pattern in Reed-Sternberg (RS) cells. However, the impact of the presence of EBV in RS cells and its prognosis are still controversial. We analysed the presence of EBV in RS cells and its influence in the clinical evolution of patients with cHL treated in two public hospitals in the city of São Paulo, Brazil. MATERIALS AND METHODS: We selected 97 patients with cHL from 1994 to 2004. Patients were only included in this study if they had (1) >18 years, (2) negative HIV serology, (3) undergone similar chemotherapy protocols, (4) paraffin blocks available with enough material for systematic review and histological reclassification and for detection of EBV in RS cells by in situ hybridization and immunohistochemistry and (5) clinical, epidemiological and laboratorial parameters available after a thorough chart review. RESULTS: EBV was identified in 52.5% of the cases. Mixed cellularity (MC) subtype was more common in EBV-related tumours (25.5%) (p=0.005). There was no difference on age, gender, stage and the presence of B symptoms between the two groups. The presence of EBV did not influence event free survival (EFS) (p=0.38) or overall survival (OS) (p=0.80) with a median follow-up of 80 months. CONCLUSION: We demonstrate that the prevalence of EBV-related cHL in this Brazilian population is 52.5% and, that, the presence of EBV does not change the clinical evolution and OS of patients treated with similar chemotherapy protocols.

BCR-ABL1-induced downregulation of WASP in chronic myeloid leukemia involves epigenetic modification and contributes to malignancy.

Chronic myeloid leukemia (CML) is a myeloproliferative disease caused by the BCR-ABL1 tyrosine kinase (TK). The development of TK inhibitors (TKIs) revolutionized the treatment of CML patients. However, TKIs are not effective to those at advanced phases when amplified BCR-ABL1 levels and increased genomic instability lead to secondary oncogenic modifications. Wiskott-Aldrich syndrome protein (WASP) is an important regulator of signaling transduction in hematopoietic cells and was shown to be an endogenous inhibitor of the c-ABL TK. Here, we show that the expression of WASP decreases with the progression of CML, inversely correlates with the expression of BCR-ABL1 and is particularly low in blast crisis. Enforced expression of BCR-ABL1 negatively regulates the expression of WASP. Decreased expression of WASP is partially due to DNA methylation of the proximal WASP promoter. Importantly, lower levels of WASP in CML advanced phase patients correlate with poorer overall survival (OS) and is associated with TKI response. Interestingly, enforced expression of WASP in BCR-ABL1-positive K562 cells increases the susceptibility to apoptosis induced by TRAIL or chemotherapeutic drugs and negatively modulates BCR-ABL1-induced tumorigenesis in vitro and in vivo. Taken together, our data reveal a novel molecular mechanism that operates in BCR-ABL1-induced tumorigenesis that can be used to develop new strategies to help TKI-resistant, CML patients in blast crisis (BC).

Reduced ABCG2 and increased SLC22A1 mRNA expression are associated with imatinib response in chronic myeloid leukemia.

Imatinib mesylate (IM) has become a standard of care in chronic myeloid leukemia (CML) therapy. Single nucleotide polymorphisms (SNPs) and altered expression in drug transporter genes may influence IM response. In order to investigate whether mRNA expression and SNPs in drug transporters are associated with IM resistance, we studied 118 chronic-phase CML patients receiving the standard dose of IM (400 mg/day). They were assigned as responders and non-responders according to European LeukemiaNet criteria (2009). mRNA expression in samples at diagnosis (without IM therapy) and outcomes after IM failure were also evaluated in subgroups of patients. Major molecular response (MMR), complete molecular response and primary and secondary resistance were all assessed. BCR-ABL1, ABCB1, ABCG2, SLC22A1 and SLCO1A2 mRNA expression and SNPs in ABCG2 and SLC22A1 genes were analyzed. ABCG2 mRNA expression in the non-responders was higher before and during IM therapy. Furthermore, ABCG2 was overexpressed in those who did not achieve MMR (P=0.027). In a subgroup of patients who switched to second-generation tyrosine kinase inhibitors, high mRNA expression of ABCG2 was associated with a risk of 24 times that of not achieving complete cytogenetic response (OR 24.00, 95% CI 1.74-330.80; P=0.018). In the responder group, patients who achieved MMR (P=0.009) presented higher mRNA levels of SLC22A1. The SNPs were not associated with mRNA expression of ABCG2 and SLC22A1. Our data suggest that elevated ABCG2 expression (an efflux transporter) could be associated with IM resistance and could impact on second-generation TKI response, whereas high SLC22A1 expression (an influx transporter) may be associated with a successful IM therapy in CML patients.

Matrix metalloproteinase-9 is consistently expressed in Hodgkin/Reed-Sternberg cells and has no impact on survival in patients with Epstein-Barr virus (EBV)-related and non-related Hodgkin lymphoma in Brazil.

Clinical and histological features of classical Hodgkin lymphoma (cHL) are primarily due to the effects of cytokines and enzymes produced by Hodgkin/Reed-Sternberg (HRS) cells and their surrounding inflammatory cells. In EBV-related cancers, the expression of viral latent membrane protein 1 correlates with an increased MMP9 expression. In this study, we evaluated the prognostic relevance of MMP9 expression and EBV status in HRS cells in patients with cHL in Brazil. We selected 97 patients with cHL for EBV and MMP9 detection. EBV was detected in 52.5%, and MMP9 expression positivity was found in 87.6%. Of all cases, there was no correlation between MMP9 expression and EBV status. Response to treatment and relapse rate was independent of MMP9 expression and EBV status. MMP9 positivity did not influence overall survival and event-free survival. The consistent and increased intensity of MMP9 expression in HRS cells make this enzyme a potential target for therapy.

Retrospective epidemiological study of Latin American patients with transfusional hemosiderosis: the first Latin American epidemiological study in iron overload--the RELATH study.

The retrospective epidemiological study of Latin Americans with transfusional hemosiderosis is the first regional patient registry to gather data regarding the burden of transfusional hemosiderosis and patterns of care in these patients. Retrospective and cross-sectional data were collected on patients ≥2 years with selected chronic anemias and minimum 20 transfusions. In the 960 patients analyzed, sickle-cell disease (48·3%) and thalassemias (24·0%) were the most frequent underlying diagnoses. The registry enrolled 355 pediatric patients (187 with sickle-cell disease/94 with thalassemia). Serum ferritin was the most frequent method used to detect iron overload. Complications from transfusional hemosiderosis were reported in ~80% of patients; hepatic (65·3%), endocrine (27·5%), and cardiac (18·2%) being the most frequent. These data indicate that hemoglobinopathies and complications due to transfusional hemosiderosis are a significant clinical problem in the Latin American population with iron overload. Chelation therapy is used insufficiently and has a high rate of discontinuation.

Estudo retrospectivo do tratamento de leucemia mielóide aguda com o transplante de medula óssea: a experiência brasileira / Retrospective study of stem cell transplantation for acute myeloid leukemia (AML): the Brazilian experience

Dados do Registro Internacional de Transplante de Medula Óssea, International Bone Marrow Transplant Registry (IBMTR) contribuem para o progresso do transplante de medula óssea (TMO) em todo o mundo. Neste artigo relatamos a experiência brasileira em leucemia mielóide aguda e comparamos os resultados do TMO com os dados internacionais. Foi realizado um estudo retrospectivo com dados de tratamento de LMA com o TMO de 16 instituições brasileiras. A análise estatística dos transplantes da modalidade autogênica (TMO auto) e alogênica (TMO alo) foi realizada com o método de Kaplan-Meier e log-rank. Todos os valores de p foram bicaudados. Foram avaliados os dados de 731 pacientes (205 TMO auto e 526 TMO alo). A mediana de sobrevida global dos pacientes submetidos ao TMO auto foi superior à dos submetidos ao TMO alo (1.035 vs 466 dias, p=0,0012). A origem das células-tronco (OCT) no TMO alo em 73% dos pacientes foi de medula óssea (CTMO), em 23% de sangue periférico (CTSP) e em 4% de cordão umbilical. No TMO auto, a OCT foi 63% de CTSP, 22% CTMO e 15% de ambas as fontes. A OCT não teve impacto na sobrevida global (SG). Não houve diferença na SG também entre os pacientes segundo a classificação FAB no TMO alo, mas os pacientes com LMA M3 com o TMO auto tiveram SG longa. Como esperado, a principal causa de óbito entre os pacientes do TMO auto foi relacionada à recidiva de doença (60%), enquanto no TMO alo as principais causas foram a doença enxerto versus hospedeiro e infecções (38%). Em ambos os grupos foi observada SG mais longa nos pacientes tratados em primeira remissão completa (1RC) quando comparados aos de segunda remissão (2RC) e outras fases (p<0,0001), tendo sido observado SG mais longa nos pacientes com LMA de novo quando comparados aos de LMA secundária. No TMO alo a SG foi mais longa com doadores aparentados (538 versus 93 dias p=0,001). A SG foi mais curta nos pacientes que utilizaram irradiação corpórea total no regime de condicionamento (p=0,0001)...

Data from the International Bone Marrow Transplant Registry (IBMTR) contribute for the improvement of Bone Marrow Transplant (BMT) worldwide. We studied the Brazilian experience in BMT for AML to compare this with international data. We performed a retrospective study by sending questionnaires to 16 BMT centers regarding clinical and treatment variables. Statistical analyses concerning autologous BMT (autoBMT) and allogeneic BMT (alloBMT) were performed using the Kaplan-Meier method and the log-rank test. All p-values were two-tailed. We collected data from 731 patients (205 autoBMT and 526 alloBMT). Median overall survival (OS) for autoBMT patients was longer than alloBMT patients (1035 vs. 466 days, p=0.0012). AlloBMT stem cell source (SCS): 73% bone marrow stem cell (BMSC), 23% peripheral blood stem cells (PBSC) and 4% umbilical cord blood. Among the autoBMT patients, the SCS was 63% PBSC, 22% BMSC and 15% both. The SCS did not impact on OS. There was no difference in OS between different FAB classifications in the alloBMT group, but in the autoBMT the M3 patients had longer survival. As expected, the main cause of mortality among autoBMT patients was related to disease relapse (60%), while in the alloBMT, to infection (38%). In both groups we found longer OS in first complete remission (1CR) compared to second (2CR) and other (p<0.0001), and longer OS in de novo AML than in secondary...