Anti-PD1 and anti-CD19 bispecific antibody and applications thereof

The present invention relates to anti-PD1 and anti-CD19 bispecific antibody and applications thereof, wherein the anti-PD1 and anti-CD19 bispecific antibody, or a variant, or a functional fragment thereof comprises: a domain capable of specifically recognizing and binding an immune cell surface antigen PD-1, wherein the domain comprises the heavy chain variable region (anti-PD-1 VH) of an anti-PD-1 specific antibody; and a domain capable of specifically recognizing and binding CD19, wherein the domain comprises the heavy chain variable region (anti-CD19 VH) of an anti-CD19 specific antibody. According to the present invention, the bispecific antibody has the whole human sequence, such that the occurrence of HAMA in clinical treatment application is effectively avoided, the occurrence of drug resistance can be effectively reduced, and the utilization efficiency and the treatment effect of the medicine can be improved; and the anti-PD-1 and anti-CD19 bispecific antibody can well mediate T cells to efficiently and specifically kill B-lymphocyte derived tumor cells compared to the existing anti-PD-1 specific antibody and the existing anti-CD19 specific antibody.