The present invention discloses an
antibody-
drug conjugate and a preparation method and application thereof, in particular, a conjugate of an anti-PD-L1
antibody and a TLR7 and / or TLR8
agonist and a pharmaceutical composition, preparation method and application thereof. The present invention obtains a modified anti-PD-L1
antibody with a
mutant cysteine by
gene editing, which basically retains the structure of the original antibody and can be used for the construction of an antibody-
drug conjugate. Through anti-tumor experiments, it was found that the obtained antibody-
drug conjugate has better activity, such as strong anti-tumor activity, can significantly improve the
survival rate of tumor-bearing animals, and has significantly
reduced toxicity, less burden on the body of experimental animals, greatly reduces the minimum effective
dose of
small molecule drugs when used alone, expands its
therapeutic window, and is expected to be used in the development of therapeutic drugs for various diseases (such as tumors, viral diseases such as
hepatitis B, etc.), with good application prospects and value.