PD-1 and LAG-3 expression in EBV-associated pediatric Hodgkin lymphoma has influence on survival.

In pediatric Hodgkin lymphoma (HL), the inability of the cytotoxic microenvironment induced by EBV presence to eliminate tumor cells could reflect the fact that the virus might be able to induce the expression of exhaustion markers to evade an immune response. Therefore, the expression of exhaustion markers in pediatric EBV-associated HL was evaluated. A balance between cytotoxic GrB and Th1 Tbet markers with regulatory Foxp3 was proved in EBV+ cases. In addition, exclusively in EBV-associated cHL, a correlation between PD-1 and LAG-3 expression was observed. Furthermore, those cases also displayed a trend to worse survival when they expressed LAG-3 and inferior event-free survival when both PD-1 and LAG-3 molecules were present. Therefore, even though a cytotoxic and inflammatory environment was supposed to be triggered by EBV presence in pediatric cHL, it seems that the virus may also induce the synergic effect of inhibitory molecules LAG-3 and PD-1 in this series. These observations may reflect the fact that the permissive and exhausted immune microenvironment succeeds to induce lymphomagenesis.

Molecular alterations in the integrated diagnosis of pediatric glial and glioneuronal tumors: A single center experience.

OBJECTIVES: Tumors of the central nervous system (CNS) are the most common pediatric solid tumors, where low grade (LGG) and high grade gliomas (HGG) represent up to 55% of CNS tumors. Current molecular classification of these tumors results in a more accurate diagnosis and risk stratification, which ultimately enables individualized treatment strategies. Identifying known alterations is a suitable approach, particularly in developing countries, where NGS approaches are not easily accessible. We sought to assess molecular alterations in BRAF and histone 3 genes. STUDY DESIGN: FISH, IHC and Sanger sequencing were performed in a series of 102 pediatric glial and glioneuronal tumors. We also correlated these results with clinical and histological findings to evaluate their usefulness as diagnostic and/or prognostic tools. RESULTS: We found that the KIAA1549-BRAF gene fusion was a relevant diagnostic tool for pilocytic astrocytoma, but not related to progression free survival (PFS) and overall survival (OS). BRAFV600E mutation was associated with a decreased OS in LGG, and with decreased PFS and OS among pilocytic astrocytomas. All HGG of the midline were H3K27M mutants, while H3G34R mutant cases were located in brain hemispheres. HGG harboring the H3K27M variant were associated with a decreased PFS and OS. CONCLUSIONS: Assessing druggable molecular markers with prognostic value is particularly important in those cases where complete resection or further radiation therapy is not possible. These potential diagnostic/prognostic markers may be suitable as further screening tests to reduce the requirement on NGS, which is not available in all laboratories. Furthermore, these results broaden data on BRAF and Histone 3 alterations in children from geographic regions, other than USA and Europe.

Childhood liver tumors in Argentina: Incidence trend and survival by treatment center. A report from the national pediatric cancer registry, ROHA network 2000-2015.

BACKGROUND: Information on the epidemiology of pediatric liver tumors in Latin America is limited. PURPOSE: To describe the incidence of liver tumors in a pediatric registry in Argentina according to geographic region, national trends over 16 years, and survival related to stage, age, sex, and care center. METHODS: Newly diagnosed liver tumors cases are registered in the Argentine Pediatric Oncology Hospital Registry (ROHA) with an estimated coverage of 91% of national cases. Age-standardized incidence rate per millon (ASR) was calculated based on the National Vital Statistics Reports. Five-year overall survival (OS) was estimated using the Kaplan-Meier method. The log-rank test was used to compare subgroup survival. RESULTS: Two hundred seven cases of hepatoblastoma (HB) and 73 of hepatocellular carcinoma (HCC) were identified. ASR of liver tumors was 1.8/million (95% confidence Interval [CI], 1.6-2.0) per year. ASR was 1.4 (1.2-1.6) for HB and 0.4 (0.3-0.5) for HCC. For HB, the highest incidence was found in the northwest region including the Altiplano. OS was 60.4% (53.4-66.8) for HB and 36.1% (25.2-47.2) for HCC. Five-year survival rate of children with metastatic HB treated at liver transplant hospitals (LTH) was 54.2% (30.3-73.0) compared to 13.3% (2.2-34.6) for those seen at other hospitals (OH) (P = .02), while for HCC this rate was 46.3% (30.7-60.6) at LTH compared to 17.5% (3.1-41.9) at OH (P = .01). CONCLUSIONS: The incidence rate of pediatric liver tumors was stable over the 16-year study period. Patients may benefit if at treatment initiation they are evaluated jointly with LTH specialists to define treatment strategies.

Changes in EBV Association Pattern in Pediatric Classic Hodgkin Lymphoma From a Single Institution in Argentina.

In classic Hodgkin lymphoma (cHL), Epstein Barr virus (EBV) association varies worldwide. Aims: Our aim was to analyze EBV association with pediatric cHL for the last 28 years. Methods: EBV presence was evaluated by EBERs in situ hybridization and LMP1 immunohistochemistry. Results: Until 2008, we found in pediatric cHL a similar percentage of EBV presence to those observed in adult cHL from developed populations. Nevertheless, in the last 8 years, an unexpected difference in cHL EBV association was proven, along with a slight bias of EBV association with the nodular sclerosis (NS) subtype. Concerning histological subtype distribution, even though MC still prevailed in the whole series, those cases diagnosed as NS showed a sustained rise from 1989 until today. Conclusion: Variations of EBV association of cHL related to geography, age, ethnicity, and histological type have been largely described when compared with different world regions, but interestingly, this single-center revised series brought to light the dynamic process behind the evolution of this relationship over time.

Guías de Vacunación en Huéspedes Especiales / Guidelines for the Vaccination of Special Hosts

Los niños con alteración de su sistema inmunológico son más vulnerables ante las infecciones que el resto de la población. Una de las formas de protegerlos de infecciones graves es a través de la vacunación, deben ser correctamente evaluados al planear los esquemas a fin de establecer los riesgos vs. los beneficios que implican inmunizarlos. El rol del médico pediatra y del médico especialista trabajando en equipo es fundamental, para que puedan beneficiarse con vacunas y esquemas especiales que requieran por su patología de base. Una protección óptima de estos pacientes incluye además la adecuada inmunización de los convivientes y del equipo médico tratante. La inmunización de los huéspedes especiales es una situación clínica compleja que requiere un análisis exhaustivo personalizado en cada caso, debido a las diferentes características de estos pacientes con enfermedades crónicas y/o inmunosuprimidos, los diversos grupos y muchos tipos de terapias inmunosupresoras que se están desarrollando y utilizando en un número cada vez mayor. Es fundamental el trabajo en equipo del médico especialista y el pediatra de cabecera para lograr el mejor control de las enfermedades inmunoprevenibles en estos pacientes de tan alta complejidad

Children with weakened immune systems are more vulnerable to infections than the rest of the population. One of the ways to protect them against serious infections is vaccination; they must be correctly evaluated when planning schedules in order to define the risks versus the benefits involved by their immunization. The role of pediatricians and medical specialists working as a team is fundamental, so that patients can benefit from vaccines and special schedules that they may require due to their underlying pathologies. Optimal protection of these patients also includes the adequate immunization of household members and their treating medical teams. The immunization of special hosts is a complex clinical situation that requires an exhaustive personalized case-by-case analysis, due to the different characteristics of these patients who have chronic diseases and / or are immunosuppressed, the various groups and many types of immunosuppressive therapies that are being developed and increasingly used. The teamwork of specialists and family pediatricians is essential to achieve the best control of immuno-preventable diseases in these highly complex patients

Germline TP53 mutations and single nucleotide polymorphisms in children / Mutaciones y polimorfismos de un único nucleótido del gen TP53 en línea germinal en niños

Mutations in the gene TP53, which codifies the tumor suppressor protein p53, are found in about 50% of tumors. These mutations can occur not only at somatic level, but also in germline. Pediatric cancer patients, mostly with additional family history of malignancy, should be considered as potential TP53 germline mutation carriers. Germline TP53 mutations and polymorphisms have been widely studied to determine their relation with different tumors' pathogenesis. Our aim was to analyze the occurrence frequency of germline TP53 mutations and polymorphisms and to relate these to tumor development in a pediatric series. Peripheral blood mononuclear cell samples from 26 children with solid tumors [PST] and 21 pediatric healthy donors [HD] were analyzed for germline mutations and polymorphisms in TP53 gene spanning from exon 5 to 8 including introns 5 and 7. These PCR amplified fragments were sequenced to determine variations. A heterozygous mutation at codon 245 was found in 1/26 PST and 0/21 HD. Comparative polymorphisms distribution, at position 14181 and 14201(intron 7), between HD and PST revealed a trend of association (p= 0.07) with cancer risk. HD group disclosed a similar polymorphism distribution as published data for Caucasian and Central/South American populations. This is the first study about TP53 variant frequency and distribution in healthy individuals and cancer patients in Argentina.

El gen que codifica para la proteína supresora de tumor p53 (TP53) se encuentra mutado en aproximadamente el 50% de los tumores. Estas mutaciones pueden presentarse como somáticas o en línea germinal. Los niños con tumores, sobre todo aquellos con historia familiar de enfermedad oncológica, deben considerarse potenciales portadores de mutaciones en línea germinal. Las mutaciones de TP53 y los polimorfismos son estudiados para determinar su relación con la patogénesis de diferentes tumores. El objetivo del trabajo fue analizar la frecuencia de mutaciones y polimorfismos en línea germinal de TP53 y relacionarlos con el desarrollo de tumor en un grupo de pacientes pediátricos. Se analizaron muestras de sangre periférica de 26 pacientes con tumores sólidos [PST] y 21 niños donantes sanos [HD] para determinar la presencia de mutaciones y polimorfismos de TP53 en línea germinal. Se analizó por PCR seguida de secuenciación, la región que comprende a los exones 5 a 8 (incluyendo intrones 5 y 7). En 1/26 PST se encontró una mutación heterocigótica en el codón 245. La distribución de los polimorfismos, en la posición 14181 y 14201 (intrón 7), entre HD y PST mostró una tendencia de asociación (p = 0.07) con el riesgo para desarrollar cáncer. La frecuencia de distribución de dichos polimorfismos en HD fue similar a la publicada para poblaciones caucásicas y de América Central/del Sur. Este estudio aporta información original sobre la frecuencia de distribución de las variantes TP53 en individuos sanos y con tumores en la Argentina.