Nucleoside analogs and uses in treating disease

A pharmaceutical composition comprised of a nucleoside dimer having the formula:

• R1—X—R2
• wherein X is a moiety PO4 or S═PO3;
• wherein R1 and R2 are the same or different nucleosides;
• wherein R1 and R2 are selected from the group consisting of β-D-deoxyfluorouridine, α-L-deoxyfluorouridine, β-L-deoxyfluorouridine, α-L-deoxycytidine, β-L-deoxycytidine, β-L-deoxyuridine, β-L-deoxyguanosine, β-L-deoxyadenosine, α-L-deoxyadenosine and nitrobenzylthionosine;
• and
• wherein R1 and R2 are attached to X through —OH groups.