The present invention belongs to the field of bio-
engineering pharmacy,
protein polypeptide drugs and
biomedical engineering, and relates to design and construction of a miniaturized fusion
antibody providing high affinity for
human epidermal growth factor receptors EGFR1 and HER2, and applications of the miniaturized fusion
antibody in
tumor targeting diagnosis and therapy, wherein the
bispecific antibody is obtained by connecting a HER2 specific domain and a EGFR1 specific domain in series through a (G4S)3 connecting
peptide and carrying out
gene recombinant expression, the full-length of the
fusion protein coding
gene is 804 bp, 268 amino acids are coded, the molecular weight of the
fusion protein is 29 kD, and the
amino acid sequence is the sequence represented by SEQ ID No:1. Compared with combination of the EGFR1 and HER2 antibodies, the bispecific miniaturized
antibody of the present invention provides significant
in vitro and
in vivo activity advantages, has advantages of
low toxicity, being rapidly cleared in non-tumor sites
in vivo, and the like, has high efficiency in targeting diagnosis and therapy, and can be used for tumor diagnosis and therapy.