Circular RNA compositions and methods

A pharmaceutical composition formulated for intravenous administration, the pharmaceutical composition comprising:

• a. a circular RNA polynucleotide comprising a non-human post-splicing 3′ group I intron fragment, an Internal Ribosome Entry Site (IRES), an expression sequence encoding a chimeric antigen receptor (CAR) or T cell receptor (TCR) complex protein, and a non-human post-splicing 5′ group I intron fragment,
• wherein the post-splicing 3′ group I intron fragment is not a T4 bacteriophage thymidylate synthase (Td) 3′ group I intron fragment, and wherein the post-splicing 5′ group I intron fragment is not a T4 bacteriophage Td 5′ group I intron fragment, and
• b. a transfer vehicle comprising (i) an ionizable lipid, (ii) a structural lipid, and (iii) a PEG-modified lipid, wherein the transfer vehicle is capable of delivering the circular RNA polynucleotide to a human immune cell present in a human subject, such that the CAR or TCR is translated in the human immune cell and expressed on the surface of the human immune cell.