A compound according to any of Formulae 1001, 1002: or a pharmaceutically acceptable salt, solvate, stereoisomer, tautomeric form or polymorphic form thereof; wherein: each K is independently O or S; each of Base 1 and Base 2 is independently a nucleobase; X is -N(R 3)-, -C N(R 3)-, -O-, -C O- or -S-; Y is -N(R 4)-, -C N(R 4)-, -O-, -C O- or -S-; L is alkylene, cycloalkylene, heteroalkylene, cycloheteroalkylene, arylene or heteroarylene; each of R 1 and R 2 is independently -OH or -F; each of R 3 and R 4 is independently H, alkyl or heteroalkyl, or R 3 and R 4 join to form a ring; W is -N(R 9)-, -O- or -S-; R 9 is H or alkyl; R 6 is H, alkyl, heteroalkyl, cycloalkyl, cycloheteroalkyl, aryl, heteroaryl or - m C Q 1; Q 1 is -OR 10, -S R 10 or -NR 11 R 12; each G is independently CR 7 R 8; m is 1 or 2; each R 10 is alkyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl or cycloalkenyl; R 11 and R 12 are selected as follows: i) R 11 and R 12 are each independently hydrogen, alkyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl or cycloalkenyl; or ii) R 11 and R 12 together with the nitrogen atom on which they are substituted form a 3-7 membered heterocyclic or heteroaryl ring; and R 7 and R 8 are selected as follows: i) R 7 and R 8 are each independently hydrogen, alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, aralkyl, heteroaryl, heteroaralkyl, cycloalkyl, cycloalkenyl, alkylheterocyclyl or alkylheteroaryl, wherein alkyl is optionally substituted by alkoxy; or ii) R 7 and R 8 together with the carbon atom to which they are attached form a 3-7 membered cycloalkyl ring. each K is independently O or S; each of Base 1 and Base 2 is independently a nucleobase; X is -N(R 3)-, -C N(R 3)-, -O-, -C O- or -S-; Y is -N(R 4)-, -C N(R 4)-, -O-, -C O- or -S-; L is alkylene, cycloalkylene, heteroalkylene, cycloheteroalkylene, arylene or heteroarylene; each of R 1 and R 2 is independently -OH or -F; each of R 3 and R 4 is independently H, alkyl or heteroalkyl, or R 3 and R 4 join to form a ring; W is -N(R 9)-, -O- or -S-; R 9 is H or alkyl; R 6 is H, alkyl, heteroalkyl, cycloalkyl, cycloheteroalkyl, aryl, heteroaryl or - m C Q 1; Q 1 is -OR 10, -S R 10 or -NR 11 R 12; each G is independently CR 7 R 8; m is 1 or 2; each R 10 is alkyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl or cycloalkenyl; R 11 and R 12 are selected as follows: i) R 11 and R 12 are each independently hydrogen, alkyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl or cycloalkenyl; or ii) R 11 and R 12 together with the nitrogen atom on which they are substituted form a 3-7 membered heterocyclic or heteroaryl ring; and R 7 and R 8 are selected as follows: i) R 7 and R 8 are each independently hydrogen, alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, aralkyl, heteroaryl, heteroaralkyl, cycloalkyl, cycloalkenyl, alkylheterocyclyl or alkylheteroaryl, wherein alkyl is optionally substituted by alkoxy; or ii) R 7 and R 8 together with the carbon atom to which they are attached form a 3-7 membered cycloalkyl ring. i) R 11 and R 12 are each independently hydrogen, alkyl, alkenyl, alkynyl, aryl, aralkyl, cycloalkyl or cycloalkenyl; or ii) R 11 and R 12 together with the nitrogen atom on which they are substituted form a 3-7 membered heterocyclic or heteroaryl ring; and i) R 7 and R 8 are each independently hydrogen, alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, aralkyl, heteroaryl, heteroaralkyl, cycloalkyl, cycloalkenyl, alkylheterocyclyl or alkylheteroaryl, wherein alkyl is optionally substituted by alkoxy; or ii) R 7 and R 8 together with the carbon atom to which they are attached form a 3-7 membered cycloalkyl ring.