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IntroductionThere is consistent evidence that FLT3 may be a driver gene in B-ALL and that selected cases may benefit from the use of FLT3 inhibitors. Our study was conducted to evaluate the frequency and types of FLT3 mutations in pediatric patients with B-ALL, the relative expression of this gene, and their influence on clinical evolution.MethodsWe evaluated 156 children with B-ALL treated between July 2018 and September 2023. Screening for FLT3 mutations was performed using RFLP and fragment analysis, while FLT3 expression was assessed by qPCR.ResultsFLT3-TKD and/or FLT3-JM-INDEL mutations were found in 8 patients (5.1%). We did not identify any ITD-type mutations. None of the patients with identified FLT3 mutations presented recurrent rearrangements in B-ALL or alterations in the IKZF1, PAX5, or ERG genes, suggesting that FLT3 mutation may serve as the driving mechanism for leukemia in these cases. Two (2/8) patients with FLT3 mutations experienced disease relapse. Although we did not observe FLT3 overexpression among patients with FLT3 mutations, FLT3 expression levels were higher in these patients compared to WT patients. Four FLT3-WT patients presented FLT3 overexpression, defined as RQ > 10. FLT3 mutations or overexpression were not associated with relapses or survival rates.DiscussionOur findings do not support the inclusion of FLT3 as a routine marker in the risk stratification of B-ALL patients; nevertheless, FLT3 alterations may be relevant for guiding personalized treatment approaches in specific clinical contexts.

BackgroundFamilial aggregation in childhood leukemia is associated with epidemiological and genomic factors. Albeit epidemiological studies on the familial history of hematological malignancies (FHHMs) are scarce, genome-wide studies have identified inherited gene variants associated with leukemia risk. We revisited a dataset of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) patients to explore the familial aggregation of malignancies among their relatives.MethodsA series of 5,878 childhood leukemia (≤21 years of age) from the EMiLI study (2000–2019) were assessed. Lack of well-documented familial history of cancer (FHC) and 670 cases associated with genetic phenotypic syndromes were excluded. Leukemia subtypes were established according to World Health Organization recommendations. Logistic regression-derived odds ratios (ORs) and 95% confidence intervals (CIs) were performed and adjusted by age as a continuous variable, where ALL was the reference group for AML and conversely. The pedigree of 18 families with excess hematological malignancy was constructed.ResultsFHC was identified in 472 of 3,618 eligible cases (13%). Ninety-six of the 472 patients (20.3%) had an occurrence of FHHMs among relatives. Overall, FHC was significantly associated with AML (OR, 1.36; 95% CI, 1.01–1.82; p = 0.040). Regarding the first-degree relatives, the OR, 2.92 95% CI,1.57-5.42 and the adjOR, 1.16 (1.03-1.30; p0.001) were found for FHC and FHHM, respectively.ConclusionOur findings confirmed that AML subtypes presented a significant association with hematological malignancies in first-degree relatives. Genomic studies are needed to identify germline mutations that significantly increase the risk of developing myeloid malignancies in Brazil.

Previous studies have suggested a variation in the incidence of acute promyelocytic leukemia (APL) among the geographic regions with relatively higher percentages in the Latin American population. We aimed to explore the population burden of pediatric APL, gathering information from the population-based cancer registry (PBCR) and the diagnosis of APL obtained through incident cases from a hospital-based cohort. The homozygous deletion in glutathione S-transferases (GSTs) leads to a loss of enzyme detoxification activity, possibly affecting the treatment response. Mutations in the RAS pathway genes are also considered to be a key component of the disease both in the pathogenesis and in the outcomes. We have assessed mutations in a RAS–MAP kinase pathway (FLT3, PTPN11, and K-/NRAS) and GST variant predisposition risk in the outcome. Out of the 805 children and adolescents with acute myeloid leukemia (AML) who are registered in the PBCR, 35 (4.3%) were APL cases. The age-adjusted incidence rate (AAIR) was 0.03 per 100,000 person-years. One-hundred and sixty-three patients with APL were studied out of 931 AML cases (17.5%) from a hospital-based cohort. Mutations in FLT3, KRAS, and NRAS accounted for 52.1% of the cases. Patients with APL presented a 5-year probability of the overall survival (OS) of 67.3 ± 5.8%. A GST-theta 1 (GSTT1) null genotype conferred adverse prognosis, with an estimated hazard ratio of 2.8, 95% confidence interval (CI) 1.2–6.9. We speculate that the GSTT1 polymorphism is associated with therapeutics and would allow better OS of patients with APL with a GSTT1 null genotype.

Coelhos inoculados com tripomastigotas da cepa Ernestina do Trypanosoma cruzi tiveram parasitemias, demonstradas pelo xenodiagnóstico, até cinco meses e meio após a infecção. O tratamento de alguns desses coelhos com benzonidazol, na dose de 8mg/kg durante sessenta dias, após dois meses de infecção, resultou na negativação dos xenos após 30 dias de uso da medicação. Os coelhos chagásicos crônicos, após seis meses de infecção, já tinham a parasitemia subpatente quando foram submetidos a tratamento idêntico àqueles da fase aguda. Em ambos os casos, os coelhos tratados com benzonidazol tiveram títulos de anticorpos humorais semelhantes àqueles verificados nos coelhos chagásicos não- tratados, inclusive durante a quimioterapia. A não alteração da imunidade humoral em coelhos tratados foi comprovada quando animais chagásicos e não chagásicos submetidos ao tratamento produziram títulos de anticorpos hemolíticos idênticos àqueles verificados nos animais não-tratados. Em acentuado contraste, a função imune timo-dependente foi severamente alterada pelo uso do benzonidazol. As reações de hipersensibilidade tardia contra um antígeno sub- celular do T. cruzi foram suprimidas durante a vigência do tratamento dos coelhos chagásicos. Paralelamente, estas reações eram intensas nos coelhos chagásicos não-tratados e negativas em coelhos controles normais. Todavia, as reações cutâneas tornaram-se novamente positivas 10 dias após o tratamento. Foi interessante notar que as reações de hipersensibilidade tardia in vivo, em coelhos imunizados com BCG e testados com PPD ou em coelhos sensibilizados com DNCB também foram suprimidas durante o tratamento com o benzonidazol. Contudo, as reações de imunidade celular contra estes antígenos também reverteram aos valores normais 7 a 10 dias após a suspensão do benzonidazol. Resultados semelhantes foram relatados em relação ao nifurtimox, outra droga utilizada no tratamento da doença de Chagas. 0 benzonidazol e o nifurtimox são compostos nitro-aromáticos cuja nitrorredução resulta na formação de metabólitos intermediários potencialmente citotóxicos para o protozoário e para as células do hospedeiro.Rabbits inoculated with trypomastigotes of the Ernestina strain of Trypanosoma cruzi showed parasitemias, which were demonstrated by xenodiagnosis during five and half months of the infection. The administration of 8mg/kg/day for 2 months of benznidazole in rabbits with two months infection resulted in persistently negative xenodiagnoses after 30 days of chemotherapy. Also rabbits with chronic Chagas' disease showing negative parasitemia six months after infection were treated with benznidazole. Both groups of rabbits that received intraperitoneal injections of the drug had titers of serum antibodies to the parasite similar to those shown in untreated T. cruzi-infected rabbits. That the humoral antibody response is not altered by the benznidazole was demonstrated in other experiments, which showed that the animals under chemotherapy can produce hemolytic antibody titers as high as those found in Controls as wellas in T. cruzi-infected untreated rabbits. In marked contrast, the thymus-dependent immune function was severely affected by benznidazole. The delayed-type hypersensitivity reaction against a T. cruzi subcellular antigen was suppressed during chemotherapy, whereas the reaction was consistently present in untreated T. cruzi-infected rabbits. However, delayed-type hypersensitivity against the parasite antigen could be elicited 10 days after cessation of treatment. Also delayed hypersensitivity in rabbits immunised with BCG and tested using PPD or in rabbits sensitised to DNCB were also suppressed by benznidazole treatment. It has been shown therefore that both drugs used for treating Chagas' disease can produce profound alterations in the thymus-dependent immune response. Benznidazole and nifurtimox are nitro-aromatic compounds that undergo enzymatic reduction with production of intermediate metabolites that can be strongly cytotoxic for the T. cruzi and for the mammalian cells.

T-cell acute lymphoblastic leukemia (T-ALL) is a biologically heterogeneous malignancy, which reflects distinctive stages of T-cell differentiation arrest. We have revisited a cohort of pediatric T-ALL, in order to test if immunophenotypes associated with molecular alterations would predict the patient's outcome. Genetic mutations, translocations and copy number alterations were identified through Sanger sequencing, RT-PCR, FISH and multiplex ligation-dependent probe amplification (MLPA). We defined 8 immunophenotypic T-ALL subtypes through multiparametric flow cytometry: early T-cell precursor (ETP, n = 27), immature (n = 38), early cortical (n = 15), cortical (n = 50), late cortical (n = 53), CD4/CD8 double negative mature (n = 31), double positive mature (n = 35) and simple positive mature (n = 31) T-ALL. Deletions (del) or amplifications (amp) in at least one gene were observed in 87% of cases. The most frequent gene alterations were CDKN2A/Bdel (71.4%), NOTCH1mut (47.6%) and FBXW7mut (17%). ETP-ALL had frequent FLT3mut (22.2%) and SUZ12del (16.7%) (p < 0.001), while CDKN2A/Bdel were rarely found in this subtype (p < 0.001). The early cortical T-ALL subtype had high frequencies of NOTCH1mut and IL7Rmut (71%, 28.6%, respectively), whereas, mature T-ALL with double positive CD4/CD8 had the highest frequencies of STIL-TAL1 (36.7%), LEF1del (27.3%) and CASP8AP2del (22.7%). The co-existence of two groups of T-ALL with NOTCH1mut/IL7Rmut, and with TLX3/SUZ12del/NF1del/IL7Rmut, were characterized with statistical significance (p < 0.05) but only STIL-TAL1 (pOS 47.5%) and NOTCH1WT/FBXW7WT (pOS 55.3%) are predictors of poor T-ALL outcomes. In conclusion, we have observed that 8 T-ALL subgroups are characterized by distinct molecular profiles. The mutations in NOTCH1/FBXW7 and STIL-TAL1 rearrangement had a prognostic impact, independent of immunophenotype.