Atypical Multiple Sclerosis Lesions or Progressive Multifocal Leukoencephalopathy Lesions: That Is the Question

Progressive multifocal leukoencephalopathy (PML) is a serious infective disease of the central nervous system that may occur in case of severe immunosuppression or after some treatment for multiple sclerosis (MS) with natalizumab, dimethyl fumarate, and fingolimod. In these case reports, we highlight the importance of differential diagnosis between PML and MS lesions in order to provide rapidly the best treatment option, by discussing the finding of brain (magnetic resonance imaging) MRI suggestive for PML in 2 MS patients, one treated with dimethyl fumarate and the other during natalizumab withdrawal. In both cases, although brain MRI was highly suggestive for PML, the detection of John Cunningham virus-DNA copies in cerebrospinal fluid resulted in negative result. These case reports illustrate the diagnostic process in case of suspected PML, as both patients were diagnosed with suspected PML during a routine brain MRI control, and highlights the importance of providing a strict brain MRI follow-up during dimethyl fumarate treatment, although only a few cases of PML during this therapy have been detected, and during natalizumab suspension phase. In clinical practice, in case of a radiologically suspected case of PML, although not confirmed by the cerebrospinal fluid analysis, the best approach could be to perform a close radiological and clinical monitoring before starting a new MS therapy.

Extending the Interval of Natalizumab Dosing: Is Efficacy Preserved?

Extending the natalizumab interval after the 24th administration could reduce the risk of progressive multifocal leukoencephalopathy (PML). The objective is to evaluate the noninferiority of the efficacy of an extended interval dosing (EID) compared with the standard interval dosing (SID) of natalizumab. It is an observational, multicenter (14 Italian centers), retrospective cohort study, starting from the 24th natalizumab infusion to the loss of follow-up or 2 years after baseline. Patients were grouped in 2 categories according to the mean number of weeks between doses: < 5 weeks, SID; ≥ 5 weeks, EID. Three hundred and sixty patients were enrolled. Median dose interval (MDI) following 24th infusion was 4.7 weeks, with a bimodal distribution (modes at 4 and 6 weeks). Two hundred and sixteen patients were in the SID group (MDI = 4.3 weeks) and 144 in the EID group (MDI 6.2 weeks). Annualized relapse rate was 0.060 (95% CI = 0.033-0.087) in the SID group and 0.039 (95% CI = 0.017-0.063) in the EID group. The non-inferiority of EID versus SID was satisfied. In conclusion, there is no evidence of a reduced efficacy of natalizumab in an EID setting. This observation confirms previous results and together with the emerging evidence of a reduced risk of PML associated to an EID, supports the need of a randomized study to assess the need to change the standard of the natalizumab dosing schedule.

Epigenetic therapy for Friedreich ataxia

OBJECTIVE

To investigate whether a histone deacetylase inhibitor (HDACi) would be effective in an in vitro model for the neurodegenerative disease Friedreich ataxia (FRDA) and to evaluate safety and surrogate markers of efficacy in a phase I clinical trial in patients.

METHODS

We used a human FRDA neuronal cell model, derived from patient induced pluripotent stem cells, to determine the efficacy of a 2-aminobenzamide HDACi (109) as a modulator of FXN gene expression and chromatin histone modifications. FRDA patients were dosed in 4 cohorts, ranging from 30mg/day to 240mg/day of the formulated drug product of HDACi 109, RG2833. Patients were monitored for adverse effects as well as for increases in FXN mRNA, frataxin protein, and chromatin modification in blood cells.

RESULTS

In the neuronal cell model, HDACi 109/RG2833 increases FXN mRNA levels and frataxin protein, with concomitant changes in the epigenetic state of the gene. Chromatin signatures indicate that histone H3 lysine 9 is a key residue for gene silencing through methylation and reactivation through acetylation, mediated by the HDACi. Drug treatment in FRDA patients demonstrated increased FXN mRNA and H3 lysine 9 acetylation in peripheral blood mononuclear cells. No safety issues were encountered.

INTERPRETATION

Drug exposure inducing epigenetic changes in neurons in vitro is comparable to the exposure required in patients to see epigenetic changes in circulating lymphoid cells and increases in gene expression. These findings provide a proof of concept for the development of an epigenetic therapy for this fatal neurological disease.

Assessing the accuracy and reproducibility of computer-assisted analysis of (123) I-FP-CIT SPECT using BasGan (V2)

BACKGROUND AND PURPOSE

Over the last two decades (123) I-FP-CIT-SPECT, has been used to discriminate neurodegenerative Parkinsonian syndrome from other diseases. BasGan is a freely available software that assists (123) I-FP-CIT-SPECT evaluation by estimating semiquantitative values for each basal nucleus and compares the results to a database of healthy subjects. The aims of this study were: (1) to assess the accuracy of qualitative analysis and of semiquantitative, BasGan-assisted evaluations of (123) I-FP-CIT-SPECT; (2) to compare the accuracy of both methods when applied to "doubtful" cases; (3) to appreciate the reproducibility of the BasGan-assisted evaluations.

MATERIALS AND METHODS

Seventy-eight patients were included in this 4-year follow-up study. The diagnostic cut-off for semiquantitative uptake values of each basal nucleus was determined based on ROC curves analysis. Accuracy scores were calculated for the entire population and for "doubtful" cases. Intra- and interoperator reproducibility was assessed.

RESULTS

Accuracy of the software-assisted analyses was high for data from each nucleus. In "doubtful" exams accuracy was higher when using BasGan as opposed to relying solely on visual assessment. Intra- and interoperator reproducibility of the BasGan-assisted evaluations was good to excellent.

CONCLUSION

BasGan-assisted evaluations of (123) I-FP-CIT-SPECT were very useful, particularly in "doubtful" cases. Multicenter studies are mandatory before routine use of BasGan.

Molecular Genetic Study of a Metastatic Oligodendroglioma

Extracranial spread of neuroectodermal tumors is an unusual event, most frequently expected from glioblastomas and medulloblastomas. Single cases of metastatic oligodendrogliomas have been described, but no genetic data are reported. Oligodendrogliomas are characterized by distinct genetic alterations, i.e. loss of heterozygosity (LOH) of 1p and 19q; therefore, molecular genetic analysis of metastatic cases is of considerable interest. It may be instrumental in defining the distant tumor as metastatic oligodendroglioma and give clues to the genetic events associated with the highly malignant transformation. We present the case of a patient with multiple bone metastases from a cerebral oligodendroglioma. Oligodendroglioma grade II was the diagnosis both at original and second operation, performed 7 and 1 years before the extracranial dissemination. The extraneural spread presented before the local intracranial recurrence. The patient received procarbazine, lomustine, vincristine chemotherapy and radiotherapy after the second surgery. The computed tomography-guided biopsy of the bone lesions revealed tumor cells positive for GFAP, S-100 and Leu-7 and negative for cytokeratin, LCA and EMA. The genetic analysis of DNA from the original tumor, the bone metastasis and the autoptic brain tumor showed LOH of 1p; heterozygous deletion of CDKN2A/p 16 was detected as additional alteration in the metastasis and in the intracranial tumor at autopsy. TP53, MDM2 and CDKN2A/p14ARF genes were unchanged. Repeated brain surgery and extended survival may have acted as promoter of extraneural dissemination. Loss of CDKN2A most probably played an important role in the malignant progression: its involvement in metastatic potential remains to be clarified. Our data confirm that malignant transformation of oliogodendrogliomas may be undetected by histology and underscore the importance of genetic analysis. Coincidentally with intensive anticancer therapy, chemotherapy included, employed in patients with oligodendroglioma and the ensuing long survival, the frequency of metastatic oliogodendrogliomas may increase.

Keratan sulphate is a marker of differentiation of ramified microglia

Recently we reported that the keratan sulphate epitope recognised by the monoclonal antibody 5D4 is expressed by a population of ramified microglia in adult rats. As ramified microglia is believed to differentiate from ameboid microglia during postnatal development, we studied the rat brain from birth to 90 postnatal days of life with the monoclonal antibody 5D4. Contrary to all the other microglia markers until now described, keratan sulphate is not expressed by ameboid microglia and by macrophages but appears on the surface of microglia only when the cells are differentiated and show ramified processes. The keratan sulphate positive cells become evident at different times in different central nervous system areas; the first were localised in the pyriform cortex and brainstem from the end of the second postnatal week. These observations suggest that keratan sulphate expression on microglia cells is induced by differentiation and by a resting functional state. Moreover the 5D4 monoclonal antibody showed a strong diffuse positive staining of some cortical, thalamic and white matter areas during the first two postnatal weeks. This staining was transient and it does not seem biologically correlated with the expression of the keratan sulphate on differentiated microglia.

Disappearance of the Vicia villosa-positivity from the perineuronal net containing chondroitin proteoglycan after chondroitinase digestion

Anti-chondroitin unsulfated proteoglycan (COS-PG) 1B5 monoclonal antibody (MAb) and Vicia villosa agglutinin (VVA) recognize the same neuronal subset. Moreover, when in double immunofluorescence study the sections were digested with chondroitinase ABC (ChABC), a procedure necessary to create the epitope of 1B5 MAb, and incubated with VVA, no VVA positive neurons were detected. This finding suggests that VVA binds terminal N-acetyl-galactosamine present in the glycidic chains of COS-PG or of glycoproteins that form perineuronal molecular aggregates with COS-PG.