Clinical, radiological and molecular characterization of intramedullary astrocytomas

Intramedullary astrocytomas (IMAs) are rare tumors, and few studies specific to the molecular alterations of IMAs have been performed. Recently, KIAA1549-BRAF fusions and the H3F3A p.K27M mutation have been described in low-grade (LG) and high-grade (HG) IMAs, respectively. In the present study, we collected clinico-radiological data and performed targeted next-generation sequencing for 61 IMAs (26 grade I pilocytic, 17 grade II diffuse, 3 LG, 3 grade III and 12 grade IV) to identify KIAA1549-BRAF fusions and mutations in 33 genes commonly implicated in gliomas and the 1p/19q regions. One hundred seventeen brain astrocytomas were analyzed for comparison. While we did not observe a difference in clinico-radiological features between LG and HG IMAs, we observed significantly different overall survival (OS) and event-free survival (EFS). Multivariate analysis showed that the tumor grade was associated with better OS while EFS was strongly impacted by tumor grade and surgery, with higher rates of disease progression in cases in which only biopsy could be performed. For LG IMAs, EFS was only impacted by surgery and not by grade. The most common mutations found in IMAs involved TP53, H3F3A p.K27M and ATRX. As in the brain, grade I pilocytic IMAs frequently harbored KIAA1549-BRAF fusions but with different fusion types. Non-canonical IDH mutations were observed in only 2 grade II diffuse IMAs. No EGFR or TERT promoter alterations were found in IDH wild-type grade II diffuse IMAs. These latter tumors seem to have a good prognosis, and only 2 cases underwent anaplastic evolution. All of the HG IMAs presented at least one molecular alteration, with the most frequent one being the H3F3A p.K27M mutation. The H3F3A p.K27M mutation showed significant associations with OS and EFS after multivariate analysis. This study emphasizes that IMAs have distinct clinico-radiological, natural evolution and molecular landscapes from brain astrocytomas.

AB1270 RHEUMATOLOGY WORKFORCE IN LATIN AMERICA: TRAINING AND CURRENT STATUS

Background:

The demand for rheumatology care has been steadily increasing over the last few years. However, supply seems to be insufficient, according to previous research1. This situation may be at least partly explained by less physicians beginning a rheumatology residency program2.

Objectives:

We aim to identify baseline data, room for change, and to strengthen functional processes associated with the rheumatology workforce in order to improve care offered to patients living with rheumatic diseases.

Methods:

Descriptive cross-sectional study. We obtained data on each country through local PANLAR rheumatologists. They completed an online survey using the RedCap® platform, used for capture and storage of data. The sample was described according to the type of variable.

Results:

19 Latin American countries were included in this study, globally 1 rheumatologist was available per 106,838 inhabitants. The highest rates were found in Uruguay (1 per 23.695 inhabitants) and Argentina (1 per 40.384 inhabitants). The lowest rates were found in Nicaragua (1 per 640.648 inhabitants) and Guatemala (1 per 559.902 inhabitants). The ratio between women and men rheumatologists was 0,99 women per each man. The lowest proportions were found in Peru (0,26:1), and the highest in the Dominican Republic (2.5:1). The average age for rheumatologists was 51,6 (SD12,75). Lowest average ages were found in Paraguay (43,1 SD10,77) and the highest age averages were found in Peru (56,23 SD12.93). The average monthly compensation was USD $2.382,6 (SD$1.462,5). Venezuela had the lowest salary ($197), the highest salary was found in Costa Rica ($4.500). The proportion of rheumatologists trained abroad was 26,7%, ranging between 0% in Uruguay and 90% in Bolivia.

The countries with more rheumatology training programs were Brazil n = 50 and Mexico n = 20, while Ecuador, Honduras and Nicaragua don’t have any. The countries with the greatest amount of active residents were Brazil (n = 252) and Argentina (n = 100). The educational level required to enter the program was postgraduate studies in internal medicine in 42.11% of the programs. Currently, 108 residency programs in Latin America are active. Duration of residency programs is variable: 2 years (79.63% of cases), 3 years (16.67%), 4 years (1.85%), 5 years (0.96%) or 6 years (0.96%). The median monthly compensation for residents was $ 528 USD (IQR $ 774), the country with the highest payment was Costa Rica ($ 2637). Contrarily, in Cuba, Chile and Colombia there is no payment to residents. Finally, in 8 countries (42.11%) residents must not pay for their postgraduate studies, the average annual tuition expense in the rest of countries is $ 1248 (SD $ 2749).

Conclusion:

The rate of rheumatologists per inhabitant is low. The demographic characteristics and the current status of the rheumatology workforce, as well as rheumatology training in Latin-America varies widely among countries. For instance, relevant differences can be found regarding payment to rheumatologists and residents, and tuition fees. The collected information will be useful when planning regional-based strategies, as well as for future research projects in each country and within PANLAR.

References:

[1]Battafarano DF, Ditmyer M, Bolster MB, et al. 2015 American College of Rheumatology Workforce Study: Supply and Demand Projections of Adult Rheumatology Workforce, 2015-2030. Arthritis Care Res.2018;70(4):617-26

[2]Zborovski S, Rohekar G, Rohekar S. Strategies to improve recruitment into rheumatology: results of the Workforce in Rheumatology Issues Study. J Rheumatol. 2010;37:1749-55

Disclosure of Interests:

Daniel G. Fernández-Ávila: None declared, Daniela Patino-Hernandez: None declared, Sergio Kowalski: None declared, Alfredo Vargas-Caselles: None declared, Ana María Sapag Durán: None declared, Antonio Cachafeiro Vilar: None declared, Belia Meléndez: None declared, Carlos Santiago Pastelín: None declared, Cesar Graf: None declared, Chayanne Rossetto: None declared, Daniel Palleiro: None declared, Daniela Trincado: None declared, Diana Fernández-Ávila: None declared, Dina Arrieta: None declared, Gil Reyes: None declared, Jossiell Then: None declared, Manuel F. Ugarte-Gil Grant/research support from: Jannsen, Pfizer, Mario Cardiel: None declared, Nelly Colman: None declared, Nilmo Chávez: None declared, Paula Burgos: None declared, Ruben Montufar: None declared, Sayonara Sandino: None declared, Yurilis Fuentes-Silva: None declared, Enrique Soriano Grant/research support from: AbbVie, Eli Lilly, GlaxoSmithKline, Novartis, Pfizer Inc, Sandoz, Consultant of: AbbVie, Eli Lilly, GlaxoSmithKline, Novartis, Pfizer Inc, Sandoz, Speakers bureau: AbbVie, Amber, Bristol-Myers Squibb, Eli Lilly, Novartis, Pfizer Inc, Roche

Primary Esophageal Lymphoepithelioma

Lymphoepitheliomas are extremely rare outside the nasopharynx. Extranasopharyngeal lymphoepitheliomas may be located in the stomach or digestive tract, and only one single case of esophageal location has been found in our review. In many cases the tumor is related to Epstein-Barr virus infection. We report a case of undifferentiated carcinoma of the distal third of the esophagus in a 79-year-old man. Pathological examination of the esophagus revealed an undifferentiated carcinoma with lymphoid stroma (lymphoepithelioma). In situ hybridization of the neoplastic cells was negative for Epstein-Barr virus. To our knowledge, the present case is the first documented esophageal lymphoepithelioma in Western countries.

MGMT promoter methylation in Peruvian patients with glioblastoma

Purpose

O⁶-methylguanine–DNA methyltransferase (MGMT) promoter methylation predicts the outcome and response to alkylating chemotherapy in glioblastoma. The aim of this study is to evaluate the prevalence of MGMT methylation in Peruvian glioblastoma cases.

Patients and methods

We evaluated retrospectively 50 cases of resected glioblastoma during the period 2008–2013 at Instituto Nacional de Enfermedades Neoplasicas in Peru. Samples consisted of paraffin embedded and frozen tumour tissue. MGMT-promoter methylation status and the expression level of MGMT gene were evaluated by methylation-specific PCR and real-time PCR, respectively.

Results

Unmethylated, methylated and partially methylated statuses were found in 54%, 20% and 26% of paraffin-embedded samples, respectively. Methylation status was confirmed in the Virgen de la Salud Hospital and frozen samples. There was an association between the status of MGMT-promoter methylation and the level of gene expression (p = 0.001). Methylation was associated with increased progression-free survival (p = 0.002) and overall survival (OS) (p < 0.001).

Conclusion

MGMT-promoter methylation frequency in Peruvian glioblastoma is similar to that reported in other populations and the detection test has been standardised.

Stimulation of the midkine/ALK axis renders glioma cells resistant to cannabinoid antitumoral action

Identifying the molecular mechanisms responsible for the resistance of gliomas to anticancer treatments is an issue of great therapeutic interest. Δ(9)-Tetrahydrocannabinol (THC), the major active ingredient of marijuana, and other cannabinoids inhibit tumor growth in animal models of cancer, including glioma, an effect that relies, at least in part, on the stimulation of autophagy-mediated apoptosis in tumor cells. Here, by analyzing the gene expression profile of a large series of human glioma cells with different sensitivity to cannabinoid action, we have identified a subset of genes specifically associated to THC resistance. One of these genes, namely that encoding the growth factor midkine (Mdk), is directly involved in the resistance of glioma cells to cannabinoid treatment. We also show that Mdk mediates its protective effect via the anaplastic lymphoma kinase (ALK) receptor and that Mdk signaling through ALK interferes with cannabinoid-induced autophagic cell death. Furthermore, in vivo Mdk silencing or ALK pharmacological inhibition sensitizes cannabinod-resistant tumors to THC antitumoral action. Altogether, our findings identify Mdk as a pivotal factor involved in the resistance of glioma cells to THC pro-autophagic and antitumoral action, and suggest that selective targeting of the Mdk/ALK axis could help to improve the efficacy of antitumoral therapies for gliomas.

[Hemilingual abscess]

Lingual abscess is an extremely rare entity since the discovery of antibiotics, which, despite of its seriousness, it is usually a cause of death. We describe the case of a right hemilingual abscess, diagnosed by MRI scan because of its poor symptoms. This case is unique because of it affects the hemilingual central part and free edge. We discuss the most relevant aspects of this pathology.

Expression Profiling of T-Cell Lymphomas Differentiates Peripheral and Lymphoblastic Lymphomas and Defines Survival Related Genes

PURPOSE

T-Cell lymphomas constitute heterogeneous and aggressive tumors in which pathogenic alterations remain largely unknown. Expression profiling has demonstrated to be a useful tool for molecular classification of tumors.

EXPERIMENTAL DESIGN

Using DNA microarrays (CNIO-OncoChip) containing 6386 cancer-related genes, we established the expression profiling of T-cell lymphomas and compared them to normal lymphocytes and lymph nodes.

RESULTS

We found significant differences between the peripheral and lymphoblastic T-cell lymphomas, which include a deregulation of nuclear factor-kappaB signaling pathway. We also identify differentially expressed genes between peripheral T-cell lymphoma tumors and normal T lymphocytes or reactive lymph nodes, which could represent candidate tumor markers of these lymphomas. Additionally, a close relationship between genes associated to survival and those that differentiate among the stages of disease and responses to therapy was found.

CONCLUSIONS

Our results reflect the value of gene expression profiling to gain insight about the molecular alterations involved in the pathogenesis of T-cell lymphomas.

Characterization of the A673 cell line (Ewing tumor) by molecular cytogenetic techniques

The A673 cell line was established from a patient with a primary rhabdomyosarcoma (RMS), which is referred to in the literature either as a Ewing tumor (ET) or as RMS. Although the two tumoral types are associated with specific and well-characterized translocations, no cytogenetic report on this cell line has been published. We characterized the A673 cell line using a combination of spectral karyotyping (SKY), fluorescence in situ hybridization (FISH), and reverse transcriptase polymerase chain reaction (RT-PCR), which revealed the presence of a complex karyotype and a translocation involving chromosomes 11 and 22 and the fusion of EWS and FLI1 genes, both events being specific to ET. Neither cytogenetics nor molecular alterations specific to RMS were found.

Multiplex-polymerase chain reaction assay for the detection of prognostically significant translocations in acute lymphoblastic leukemia

BACKGROUND AND OBJECTIVES

The presence of specific chromosomal translocations in acute lymphoblastic leukemias (ALL) plays an important role in determining the prognosis of the patients. Our aim is to develop a highly sensitive and specific method to screen simultaneously for the four most frequent translocations in ALL: t(9;22), t(1;19), t(4;11), t(12;21).

DESIGN AND METHODS

Our approach uses a multiplex-polymerase chain reaction (PCR) method, which involves two rounds of PCR using fluorescence-labeled nested primers. The chimeric transcripts resulting from these translocations can be identified by agarose gel electrophoresis or by fluorescence analysis. To validate this method we carried out the analysis in 42 pediatric ALL samples previously studied by cytogenetic and fluorescent in situ hybridization (FISH) techniques.

RESULTS

In all samples with a known translocation detected by cytogenetic or FISH techniques, the same translocation was identified by the multiplex-PCR assay. Moreover, with this method we detected rearrangements in five patients in clinical remission and in two patients at diagnosis for whom karyotypes were normal and rearrangements had not been detected. The application of this multiplex-PCR assay was also useful in cases without cytogenetic results.

INTERPRETATION AND CONCLUSIONS

These results show that the multiplex-PCR method allows reliable, sensitive and rapid detection of the prognostically significant translocations in ALL. We believe that this assay combined with cytogenetic analysis should be the strategy of choice for the initial diagnostic phase of acute lymphoblastic leukemia, and that it could be used not only at diagnosis but also to follow-up these alterations in remission samples without previous controls.

Characterization of the murine p19(ARF) promoter CpG island and its methylation pattern in primary lymphomas

The INK4a/ARF locus encodes two different proteins involved in cell cycle control. Both molecules, p16(INK4a) and p19(ARF), inhibit cell cycle progression and have been shown to act as tumor suppressors in a variety of models. Their expression is controlled by separate promoters responding to different stimuli and they therefore show independent transcriptional regulation. We have cloned and characterized a 2.5 kb region upstream of the murine p19(ARF) gene to determine the role of DNA methylation in suppressing p19(ARF) transcription in a wide panel of murine primary T cell lymphomas. This region contains a DNA fragment with the characteristics of a CpG island similar to those described for the murine p16(INK4a) and p15(INK4b) genes. Expression of p19(ARF) is decreased in a significant number (20%) of the murine lymphomas analyzed. Overexpression of the p19(ARF) transcript is also frequent, suggesting alterations in molecules of the retinoblastoma or p53 pathways that are involved in p19(ARF) regulation. Although hypermethylation of the INK4a and INK4b promoters is frequently involved in murine lymphomas, the p19(ARF) CpG island is infrequently methylated in the murine primary lymphomas studied in this work. Since loss of p19(ARF) expression cannot be explained as the result of homozygous deletions or hypermethylation of the ARF gene, other regulatory mechanisms seem to be altered in these malignancies.

Loss of heterozygosity at the proximal-mid part of mouse chromosome 4 defines two novel tumor suppressor gene loci in T-cell lymphomas

Recent studies in our laboratory reported frequent loss of heterozygosity (LOH) on mouse chromosome 4 in T-cell lymphomas, identifying three candidate tumor suppressor regions (TLSR1-3). To determine the possible existence of other tumor suppressor gene loci on the proximal-mid part of chromosome 4 and to clarify whether the p16(INK4a) (alpha and beta) and p15(INK4b) genes are the inactivation targets of deletion at TLSR1, we have tested 73 gamma-radiation-induced T-cell lymphomas of F1 hybrid mice by LOH analysis. Frequent LOH was found at the INK4a and INK4b loci and the surrounding markers D4Mit77, D4Mit245 and D4Wsm1. In addition, we identified two distinct regions of significant allelic losses in the proximal-mid part of chromosome 4, defined by the markers D4Mit116 (TLSR4) and D4Mit21 (TLSR5). Taken together, this evidence and our previous data indicate the existence of at least five different candidate sites for tumor suppressor genes on chromosome 4, thus revealing a main role for this chromosome in the development of mouse T-cell lymphomas.

Instability of the D4Mit12 microsatellite marker in C57BL/6J x BALB/cJF1 hybrid mice is independent of the tumor phenotype

We examined the stability of different types of DNA microsatellite markers in gamma-radiation-induced thymic lymphomas as well as normal, nontumorous tissues of F1 hybrid mice derived from the parental strains C57BL/6J, RF/J, and BALB/cJ. Surprisingly, the D4Mit12 microsatellite showed genomic instability in a significant fraction of DNAs of the (C57BL/6J x BALB/cJ) F1 hybrids with independence of the tumor phenotype. This instability was not found in the reciprocal F1 DNAs, in DNAs of the parental strains, or in DNAs of (C57BL/6J x RF/J) F1 hybrid mice. These results suggest that the instability of the D4Mit 12 microsatellite is dependent on its repeat length, the genetic background of F1 hybrids, and the maternal origin of the C57BL/6J allele.

Frequent allelic losses of 9p21 markers and low incidence of mutations at p16(CDKN2) gene in non-Hodgkin lymphomas of B-cell lineage

We present an allelotype analysis of 35 cases of non-Hodgkin lymphomas and normal pairs using four microsatellite markers that flank the region occupied by the CDKN2 gene locus at 9p21. Frequent allelic losses (LOH) were detected in B-cell lineage NHLs, including Burkitt lymphoma (33.3% of total, if we only consider high grade tumors). In five of these tumors LOH did not include the CDKN2 gene. Mutational analysis of exon 1 and 2 of CDKN2 (SSGP and sequencing of abnormal bands) revealed a nonsense mutation (Arg72Ter) in one tumor (case 10), where the second hit of the Knudson's model consisted of the elimination of the wild type allele. In view of these results, the hypothesis of two different candidate tumor suppressor gene regions around the CDKN2 locus remains an intriguing possibility.

Inactivation of the cyclin-dependent kinase inhibitor p15INK4b by deletion and de novo methylation with independence of p16INK4a alterations in murine primary T-cell lymphomas

A wide panel of murine induced T-cell lymphomas have been analysed for p16INK4a or p15INK4b alterations. Only one gamma-radiation-induced lymphoma showed p16INK4a homozygous deletion and no other intragenic mutations were found in these INK4 genes. However, de novo methylation of the 5' CpG islands of the murine p15INK4b and p16INK4a genes was found to be highly frequent. While p16INK4a hypermethylation was found in 36% of the neutron-radiation-induced lymphomas and 15% of the gamma-radiation-induced lymphomas, de novo methylation of p15INK4b occurs in 88% and 42% of these tumors respectively, correlating with deficient expression of the corresponding mRNA and allelic losses in the p15INK4b and p16INK4a chromosome location. These data represent, to our knowledge, the first report on the significant involvement of hypermethylation of these INK4 genes in murine primary tumors. Moreover, they show the importance of allelic losses and CpG island methylation of p15INK4b gene inactivation and support a tumor suppressor role for p15INK4b in T-cell lymphomas independent of p16INK4a.