The invention relates to compositions and methods for their preparation, manufacture and therapeutic use wherein those composition comprise of one or more polynucleotides (e.g., mRNAs) encoding a binding molecule (e.g., an antibody or an antigen binding portion thereof) which specifically binds to CTLA-4 (cytotoxic T-lymphocyte-associated protein 4). The therapeutic methods disclosed herein comprise, e.g., the administration of one or more mRNAs encoding an anti-CTLA-4 antibody or an antigen-binding portion thereof 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 disclosed mRNA or mRNAs encoding the anti-CTLA-4 antibody or an antigen-binding portion thereof are administered intratumorally. When several mRNAs are used to express the disclosed anti-CTLA-4 antibodies or antigen-binding portions thereof, the ratio of mRNAs can be the same or different.