The present disclosure relates to the use of nucleic acid (e.g., mRNA) combination therapies for the treatment of cancer. The disclosure provides compositions, and methods for their preparation, manufacture, and therapeutic use, wherein those compositions comprise at least two polynucleotides (e.g., mRNAs) in combination wherein the at least two polynucleotides are selected from the group consisting of (i) a polynucleotide encoding an immune response primer (e.g., IL23), (ii) a polynucleotide encoding an immune response co-stimulatory signal (e.g., OX40L), (iii) a polynucleotide encoding a checkpoint inhibitor (e.g., an anti CTLA-4 antibody), and, (iv) a combination thereof. The therapeutic methods disclosed herein comprise, e.g., the administration of a combination therapy disclosed herein for the treatment of cancer, e.g., by reducing the size of a tumor or inhibiting the growth of a tumor, in a subject in need thereof. In some aspects, the combination therapies disclosed herein disclosed are administered intratumorally.