The present invention provides methods for treating, reducing the severity, or inhibiting the growth of cancer (e.g., a B-cell cancer such as Hodgkin's lymphoma or acute lymphoblastic leukemia). The methods of the present invention comprise administering to a subject in need thereof a therapeutically effective amount of an antibody or antigen-binding fragment thereof that specifically binds to programmed death 1 (PD-1) receptor in combination with a therapeutically effective amount of a bispecific antibody that specifically binds to CD20 and CD3.