Immunogen, Inc.

Sharon D Wilhelm

Ravi V J Chari

Wayne Charles Widdison

Rajeeva Singh

Yelena V Kovtun

Linkers for binding drugs to cell binding agents are modified to hydrophilic linkers by incorporating a polyethylene glycol spacer. The potency or the efficacy of the cell-binding agent-drug conjugates is surprisingly enhanced several folds in a variety of cancer cell types, including those expressing a low number of antigens on the cell surface or cancer cells that are resistant to treatment. A method for preparing maytansinoids bearing a thioether moiety and a reactive group which allows the maytansinoid to be linked to a cell-binding agent in essentially a single step is also provided.

Potent conjugates and hydrophilic linkers

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.

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Brookline, MA, United States of America

Sharon D Wilhelm