Some embodiments provided herein are chimeric costimulatory antigen receptor (CoStAR), useful in adoptive cell therapy (ACT), and cells comprising the CoStAR. In some embodiments, the CoStAR can act as a modulator of cellular activity enhancing responses to defined antigens. In some embodiments, CoStAR and/or fusion proteins, nucleic acids encoding the CoStAR and therapeutic uses thereof are also provided.