Abstract Details

Title Gene Expression Profiles of Proteins Involved in Cladribine Metabolism and their Possible Correlation with Epstein-Barr Virus Variants

Topic Multiple Sclerosis

Presentation(s) P2 - Poster Session 2 (5:30 PM-6:30 PM)

Poster/Presentation
Number 15-096

Objective To assess a method to identify possible drug resistant multiple sclerosis (MS) patients, and to assess the effect of allelic variation of Epstein-Barr nuclear antigen 2 (EBNA2) on cladribine (2-CdA) metabolism.

Background

Cladribine (2-CdA) is phosphorylated in its active compound 2-chlorodeoxyadenosine 5’-monophosphate (2-CdAMP) by deoxycytidine kinase (DCK).

Design/Methods DNA, RNA and cDNA extractions were conducted with Qiamp mini (Qiagen), TRIzol (Invitrogen), and Omniscript (Qiagen), respectively; Gene expression and allele identification were analysed with QX200 digital droplet PCR (Biorad). Peripheral blood mononuclear cells (PBMC) were obtained from 40 patients with relapsing-remitting MS (RRMS), free from therapy for at least 3 months. After obtaining DNA, RNA and cDNA, from the PBMC samples, the expression of deoxycytidine kinase (DCK), NT5C1A, NT5C2 and EBNA2 alleles was evaluated.

Results DCK and NT5C2 expression was comparable; NT5C1A expression was lower. The DCK/NT5C1A ratio was greater than 1 in 38/40 of samples analysed. The DCK/NT5C2 ratio ranged from 0.2 to 1.9. Spearman analysis demonstrated a moderate level of correlation (r2=0.27; p=0.01) between the two ratios. To evaluate whether Epstein-Barr virus (EBV) variants can affect 2-CdA metabolism, we stratified the expression data obtained in 12 samples, irrespective of the EBNA2 alleles (1.2 [MS-associated; n=5] and 1.3 [healthy donor-associated; n=7]) without observing significant differences among the two groups.

Conclusions Although no association was demonstrated here, we have previously demonstrated associations between EBNA2 alleles and MS. These results show that a protocol for the evaluation of 2-CdA metabolism in peripheral blood could be useful in patient management, given the degree of variability existing among the genes involved in this process. The lack of correlation with EBV alleles may be due to the small number of observations. Our preliminary data needs to be further explored in a larger population of patients receiving treatment with 2-CdA and correlated with clinical parameters.

Authors/Disclosures
PRESENTER	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
C Romano	No disclosure on file
	No disclosure on file
	No disclosure on file
Marco Salvetti, MD	Dr. Salvetti has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for sanofi. Dr. Salvetti has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for biogen. The institution of Dr. Salvetti has received research support from bms.

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