Pharmaceutical composition comprising particles comprising a complex of a double-stranded polyribonucleotide and a polyalkyleneimine

An aqueous composition comprising one or more particles, wherein

• (a) each particle comprises a complex of at least one double-stranded polyribonucleotide, or a salt or solvate thereof, and at least one polyalkyleneimine, or a salt and/or solvate thereof, wherein
• (i) the double-stranded polyribonucleotide is polyinosinic-polycytidylic acid [poly(I:C)], wherein
• at least 60% of the double-stranded polyribonucleotides have at least 850 base pairs,
• at least 70% of the double-stranded polyribonucleotides have between 400 and 5000 base pairs, and
• between 20% and 45% of the double-stranded polyribonucleotides have between 400 and 850 base pairs;
• and
• (ii) the polyalkyleneimine comprises at least 95% linear polyethyleneimines,
• wherein the average molecular weight of the linear polyalkyleneimine is between 17 and 23 kDa and the polydispersity index is <1.5, and
• wherein the ratio of the number of moles of nitrogen of the polyalkyleneimine to the number of moles of phosphorus of the double-stranded polyribonucleotide is between 2.5 and 5.5;
• and
• (b) the one or more particles each have a z-average diameter measured according to ISO 22412:2008 of between 30 nm and 150 nm.