The present specification relates to adenine conjugate compounds represented by the formula (1), wherein A, L1, L2, X1, R1, R2, R3, and m are as defined herein, or their pharmaceutically acceptable salts. Compounds of formula (1) have immunostimulating properties and may therefore be useful in therapy, for example as vaccine adjuvants. The present specification also relates to a process for preparing adenine conjugate compounds and pharmaceutically acceptable salts thereof, and to pharmaceutical compositions comprising adenine conjugate compounds and their pharmaceutically acceptable salts.