Peptide-Cleavable Self-immolative Maytansinoid Antibody-Drug Conjugates Designed To Provide Improved Bystander Killing.

A new type of antibody-drug conjugate (ADC) has been prepared that contains a sulfur-bearing maytansinoid attached to an antibody via a highly stable tripeptide linker. Once internalized by cells, proteases in catabolic vesicles cleave the peptide of the ADC's linker causing self-immolation that releases a thiol-bearing metabolite, which is then -methylated. Conjugates were prepared with peptide linkers containing only alanyl residues, which were all l isomers or had a single d residue in one of the three positions.

Synthesis and Evaluation of Camptothecin Antibody-Drug Conjugates.

Antibody-drug conjugates (ADCs) that incorporate the exatecan derivative DXd in their payload are showing promising clinical results in solid tumor indications. The payload has an F-ring that also contains a second chiral center, both of which complicate its synthesis and derivatization. Here we report on new camptothecin-ADCs that do not have an F-ring in their payloads yet behave similarly to DXd-bearing conjugates and .

A New Triglycyl Peptide Linker for Antibody-Drug Conjugates (ADCs) with Improved Targeted Killing of Cancer Cells.

A triglycyl peptide linker (CX) was designed for use in antibody -: drug conjugates (ADC), aiming to provide efficient release and lysosomal efflux of cytotoxic catabolites within targeted cancer cells. ADCs comprising anti-epithelial cell adhesion molecule (anti-EpCAM) and anti-EGFR antibodies with maytansinoid payloads were prepared using CX or a noncleavable SMCC linker (CX and SMCC ADCs). The in vitro cytotoxic activities of CX and SMCC ADCs were similar for several cancer cell lines; however, the CX ADC was more active (5-100-fold lower IC50) than the SMCC ADC in other cell lines, including a multidrug-resistant line.

Development of Anilino-Maytansinoid ADCs that Efficiently Release Cytotoxic Metabolites in Cancer Cells and Induce High Levels of Bystander Killing.

Antibody anilino maytansinoid conjugates (AaMCs) have been prepared in which a maytansinoid bearing an aniline group was linked through the aniline amine to a dipeptide, which in turn was covalently attached to a desired monoclonal antibody. Several such conjugates were prepared utilizing different dipeptides in the linkage including Gly-Gly, l-Val-l-Cit, and all four stereoisomers of the Ala-Ala dipeptide. The properties of AaMCs could be altered by the choice of dipeptide in the linker.

Metabolites of antibody-maytansinoid conjugates: characteristics and in vitro potencies.

Several antibody-maytansinoid conjugates (AMCs) are in clinical trials for the treatment of various cancers. Each of these conjugates can be metabolized by tumor cells to give cytotoxic maytansinoid metabolites that can kill targeted cells. In preclinical studies in mice, the cytotoxic metabolites initially formed in vivo are further processed in the mouse liver to give several oxidized metabolic species.