Abstract: The present disclosure provides methods for treating, reducing the severity, or inhibiting the growth of cancer (e.g., prostate cancer or metastatic castration-resistant prostate cancer). The methods of the present disclosure comprise administering to a subject in need thereof a therapeutically effective amount of a bispecific antibody or antigen-binding fragment thereof that specifically binds prostate-specific membrane antigen (PSMA) and CD28 in combination with an antibody or antigen-binding fragment thereof that specifically binds to programmed death receptor-1 (PD-1).