P11.22.A Prognostic and predictive relevance of immunohistochemically determined p53 mutation in glioblastoma

Background

It can be expected that molecular biomarkers will increasingly affect clinical decisions and lead to the development of more personalized therapies in glioblastoma (GBM) in the future. In several other tumor entities TP53 gene mutation or p53 immunoreactivity (IR) serve as a prognostic marker, significantly affecting overall survival (OS) and progression-free survival (PFS). Such an association has not yet sufficiently been demonstrated in GBM. However, there are known prognostic markers in GBM, notably MGMT promotor methylation (mMGMT) which also serves as an important predictive marker leading to a better response to temozolomide chemotherapy. Our aim was to evaluate retrospectively if p53 mutation determined via immunohistochemistry (IHC) could act as a prognostic or predictive marker in GBM.

Material and Methods

Tumor samples of 195 treatment-naïve patients with IDHwt GBM that had been stained with the p53 antibody DO-7 were subdivided into 2 different groups by p53 IHC. Samples were considered as p53mut when strong p53 IR was detected in ≥10% of all tumor cells and as p53wt when in <10%. Treatment, further molecular and survival data were gathered retrospectively for all patients. Statistical analyses were performed with SPSS.

Results

The frequency of p53mut was 36.4% (71/195). p53mut tumors showed a significantly higher IR with Ki-67 proliferation marker (p=0.005) and p53wt seemed to be associated with multifocal primary tumor localization, though not statistically significant (p=0.107). There was no significant difference between p53wt and p53mut regarding gender, age, extent of resection, adjuvant therapy, occurrence of seizures, mMGMT or ATRX loss. The p53 status was not associated with OS or PFS. Factors that univariately led to significantly longer OS and PFS were younger age, unilateral or unifocal primary tumor localization, gross-total resection, higher Karnofsky Performance Status (KPS), mMGMT and adjuvant treatment via Stupp regimen instead of radiotherapy alone, the latter being significantly better than best supportive care. In multivariate survival analyses only age <65 years, the Stupp regimen more than radiotherapy alone and KPS ≥80% significantly prolonged both OS and PFS. Unifocal primary tumor localization led to longer OS and mMGMT led to longer PFS independently. The p53 status did not significantly affect the response to different adjuvant therapy regimens neither concerning OS nor PFS.

Conclusion

Based on our study, p53 IR has no prognostic or predictive significance in IDHwt GBM. There have been previous studies with similar and others with contradicting results. Remarkable is the discordance of the used IR thresholds between different studies. Further studies should aim to revalidate the staining threshold and improve the concordance between TP53 gene sequencing and p53 IHC in IDHwt GBM.

Can water disinfection prevent the transmission of infectious koi herpesvirus to naïve carp? - a case report

Hygienic measures such as disinfection are important tools for the maintenance of fish health in aquaculture. While little information is available on the disinfection of water intended for fish containment, Huwa-San^® , a disinfectant used in food and water industries, was used for daily treatment at concentrations of approximately 60 ppm over a total period of 3 months (experiment 1) with a 3-week treatment-free interval after 2 months (experiment 2). During this period, koi herpesvirus (KHV) was added to the water of two aquaria, one used as a normal contact control, the other one receiving daily water disinfectant treatments that prevented KHV infection of carp. In the second experiment, Huwa-San^® treatment was interrupted and KHV infection was prevalent. However, when naïve fish were introduced to the same aquarium after re-application of disinfectant, KHV could not be detected in those naïve fish. Whilst KHV could not be detected in samples where disinfectant had been applied, it was present in samples of naïve fish cohabiting with infection contact control animals which had undergone no disinfectant treatment over experiments 1 and 2. The results presented here show that water treatment with a disinfectant may prevent transmission of infectious KHV to naïve carp cohabited with infected carp.

Examination of the early infection stages of koi herpesvirus (KHV) in experimentally infected carp, Cyprinus carpio L. using in situ hybridization

Koi herpesvirus (KHV) causes a highly infectious disease afflicting common carp and koi, Cyprinus carpio L. Various molecular and antibody-based detection methods have been used to elucidate the rapid attachment and dissemination of the virus throughout carp tissues, facilitating ongoing development of effective diagnostic approaches. In situ hybridization (ISH) was used here to determine the target tissues of KHV during very early infection, after infecting carp with a highly virulent KHV isolate. Analysis of paraffin-embedded tissues (i.e. gills, skin, spleen, kidney, gut, liver and brain) during the first 8 h and following 10 days post-infection (hpi; dpi) revealed positive signals in skin mucus, gills and gut sections after only 1 hpi. Respiratory epithelial cells were positive as early as 2 hpi. Viral DNA was also detected within blood vessels of various tissues early in the infection. Notable increases in signal abundance were observed in the gills and kidney between 5 and 10 dpi, and viral DNA was detected in all tissues except brain. This study suggests that the gills and gut play an important role in the early pathogenesis of this Alloherpesvirus, in addition to skin, and demonstrates ISH as a useful diagnostic tool for confirmation of acutely infected carp.

Susceptibility of koi x crucian carp and koi x goldfish hybrids to koi herpesvirus (KHV) and the development of KHV disease (KHVD)

Hybrids of koi, Cyprinus carpio x crucian carp, Carassius carassius and koi x goldfish, Carassius auratus, proved to be susceptible to koi herpesvirus (KHV, syn. CyHV-3) and developed KHV disease (KHVD). While hybrids of koi x goldfish were partly resistant to mortality following infection by immersion, most koi x crucian carp hybrids died after bath infection. KHV DNA was detected in dead fish but also in all surviving animals by different polymerase chain reactions (PCRs). According to these results, hybrid crossbreeding does not seem to prevent severe losses associated with KHV in terms of inducing KHVD. The present study showed severe losses after a waterborne KHV infection of between 35% and 100% in koi x goldfish and koi x crucian carp hybrids as well as in SPF carp.

Systematic position of copepods of the genus Achtheres (Crustacea: Copepoda: Siphonostomatoida) parasitizing perch, Perca fluviatilis L., and zander, Sander lucioperca (L.)

Parasitic copepods of the genus Achtheres commonly infect perch, Perca fluviatilis, and zander, Sander lucioperca, in Europe. The aim of this study was to verify the specific identity of these copepods. The parasites were examined morphologically, biometrically and genetically. Statistical processing of the biometrical data was based on both empirical measurements and transformed data related to total length and genital trunk width. Principal component analysis was applied to both sets of data. DNA of both parasite 'forms' was amplified using two sets of primers (EU5.8S+EU18S and 18SF1+28SR) and the products were subjected to restriction fragment length polymorphism (RFLP). Morphological differences were found in the overall shape of the copepod bodies as well as in the details of the armament of some appendages. The morphometric study emphasized the importance of second maxillae and genital process as the variables most distinctly distinguishing the two 'forms'. The two 'forms' of Achtheres differed in the DNA sequence amplified by one set of primers. RFLP revealed even more extensive differences between these two copepods. We concluded that the copepods parasitizing perch should be referred to as Achtheres percarum von Nordmann, 1832, whereas a long-forgotten name, A. sandrae Gadd, 1901, should be applied to the copepods from zander.