Adsorption of immunopotentiators to insoluble metal salts

A composition, comprising a TLR7 agonist of formula (C) and an insoluble metal salt, wherein at least 50% by mass of the TLR7 agonist of formula (C) is adsorbed to the metal salt, and wherein formula (C) is:

• wherein:
• P3 is selected from H, C1-C6alkyl, CF3, —((CH2)pO)q(CH2)pOs— and —Y-L-X—P(O)(ORX)(ORY);
• and P4 is selected from H, C1-C6alkyl, —C1-C6alkylaryl and —Y-L-X—P(O)(ORX)(ORY);
• with the proviso that at least one of P3 and P4 is —Y-L-X—P(O)(ORX)(ORY);
• RX and RY are independently selected from H and C1-C6alkyl;
• RC is selected from H and C1-C6alkyl;
• XC is selected from CH and N;
• X is selected from a covalent bond, O and NH;
• Y is selected from a covalent bond, O, C(O), S and NH;
• L is selected from, a covalent bond, C1-C6alkylene, C1-C6alkenylene, arylene, heteroarylene, C1-C6alkyleneoxy and —((CH2)pO)q(CH2)p— each optionally substituted with 1 to 4 substituents independently selected from halo, OH, C1-C4alkyl, —OP(O)(OH)2 and —P(O)(OH)2;
• each p is independently selected from 1, 2, 3, 4, 5 and 6;
• q is selected from 1, 2, 3 and 4;
• and
• s is selected from 0 and 1.