Cytotoxic agents comprising new ansamitocin derivatives

摘要

New ansamitocin derivatives bearing a linking group are disclosed. Also disclosed are methods for the synthesis of these new ansamitocin derivatives and methods for their linkage to cell-binding agents. The ansamitocin derivative- cell-binding agent conjugates are useful as therapeutic agents, which are delivered specifically to target cells and are cytotoxic. These conjugates display vastly improved therapeutic efficacy in animal tumor models compared to the previously described agents.